Google Patentsopen access

Negative electrode for secondary battery, and secondary battery — Murata Manufacturing Co., Ltd. (US20220246979A1)

ABSTRACT

Abstract

A secondary battery includes a positive electrode, a negative electrode, and an electrolytic solution. The negative electrode includes a silicon-containing material and a plurality of single-walled carbon nanotubes. The single-walled carbon nanotubes have a maximum outer diameter of 5 nanometers or less.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of PCT patent application no. PCT/JP2020/039452, filed on Oct. 21, 2020, which claims priority to Japanese patent application no. JP2019-195409, filed on Oct. 28, 2019, the entire contents of which are being incorporated herein by reference.

BACKGROUND

The present technology relates to a negative electrode for a secondary battery, and a secondary battery.

Various kinds of electronic equipment, including mobile phones, have been widely used. Such widespread use has promoted the development of a secondary battery that is smaller in size and lighter in weight and allows for a higher energy density, as a power source. The secondary battery includes a positive electrode, a negative electrode, and an electrolytic solution. The negative electrode includes a negative electrode active material and a negative electrode binder.

A configuration of the secondary battery influences a battery characteristic. Accordingly, the configuration of the secondary battery has been considered in various ways. For example, silicon monoxide is used as the negative electrode active material, and a single-walled carbon nanotube is used as a negative electrode conductor in order to obtain, for example, sufficient charge and discharge capacities. Further, a negative electrode active material which includes composite particles and carbon nanotubes is used in order to obtain, for example, a superior lifetime characteristic. The carbon nanotubes in the negative electrode active material are directly grown on surfaces of the composite particles that include, for example, silicon and natural graphite.

SUMMARY

The present application relates to a negative electrode for a secondary battery, and a secondary battery.

Consideration has been given in various ways to solve problems of the secondary battery; however, a battery capacity characteristic, an electric resistance characteristic, and a cyclability characteristic of the secondary battery each still remain insufficient. Accordingly, there is still room for improvement in terms of those characteristics.

The present technology has been made in view of such an issue, and is directed to providing a negative electrode for a secondary battery, and a secondary battery that are each able to increase the battery capacity and improve the electric resistance characteristic, the cyclability characteristic, or both according to an embodiment.

A negative electrode for a secondary battery according to an embodiment of the technology includes a silicon-containing material and a plurality of single-walled carbon nanotubes. The single-walled carbon nanotubes have a maximum outer diameter of 5 nm or less.

A secondary battery according to an embodiment of the technology includes a positive electrode, an electrolytic solution, and a negative electrode. The negative electrode includes a configuration similar to the configuration of the negative electrode for the secondary battery according to an embodiment of the technology described above.

The term “silicon-containing material” used herein is a generic term for a material including silicon (Si) as a constituent element. Thus, the silicon-containing material may be a simple substance of silicon, a compound of silicon, an alloy of silicon, or a mixture of two or more thereof.

According to the negative electrode for the secondary battery or the secondary battery of an embodiment of the technology, the negative electrode includes the silicon-containing material and the plurality of single-walled carbon nanotubes. The single-walled carbon nanotubes have a maximum outer diameter of 5 nm or less. Accordingly, it is possible to increase the battery capacity and improve the electric resistance characteristic, the cyclability characteristic, or both.

Note that effects of the technology are not necessarily limited to the effects described above and may include any of a series of suitable effects including described below in relation to the technology.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a perspective view of a configuration of a secondary battery of a laminated-film type according to an embodiment of the technology.

FIG. 2 is a sectional view of a configuration of a wound electrode body illustrated in FIG. 1 .

FIG. 3 is a plan view of a configuration of each of a positive electrode and a negative electrode illustrated in FIG. 2 .

FIG. 4 is a plan view for describing an orientation of a negative electrode conductor in the secondary battery according to an embodiment of the technology.

FIG. 5 is a plan view for describing an orientation of the negative electrode conductor in a first comparative example.

FIG. 6 is a plan view for describing an orientation of the negative electrode conductor in a second comparative example.

FIG. 7 is a flowchart for describing a procedure for preparing a negative electrode mixture slurry.

FIG. 8 is a sectional view of a configuration of another secondary battery of a cylindrical type according to an embodiment of the technology.

FIG. 9 is a perspective view of a configuration of a secondary battery of another laminated-film type according to a modification according to an embodiment.

FIG. 10 is a sectional view of a configuration of a stacked electrode body illustrated in FIG. 9 .

FIG. 11 is a block diagram illustrating a configuration of an application example of the secondary battery, which is a battery pack including a single battery.

FIG. 12 is a block diagram illustrating a configuration of an application example of the secondary battery, which is a battery pack including an assembled battery.

FIG. 13 is a block diagram illustrating a configuration of an application example of the secondary battery, which is an electric vehicle.

FIG. 14 illustrates a RBM spectrum and a five-point average differential spectrum of a negative electrode active material layer in Experiment example 3 in which the negative electrode conductor was single-walled carbon nanotubes, the negative electrode conductor was introduced at earlier introduction, and no five-point average differential peak was detected.

FIG. 15 illustrates a RBM spectrum and a five-point average differential spectrum of a negative electrode active material layer in Experiment example 2 in which the negative electrode conductor was single-walled carbon nanotubes, the negative electrode conductor was introduced at later introduction, and a five-point average differential peak was detected.

FIG. 16 illustrates a RBM spectrum and a five-point average differential spectrum of a single-walled carbon nanotube in which a five-point average differential peak was detected.

FIG. 17 illustrates a RBM spectrum and a five-point average differential spectrum of a negative electrode active material layer in a reference example in which no negative electrode conductor was introduced and no five-point average differential peak was detected.

DETAILED DESCRIPTION

One or more embodiments of the present technology are described below in detail with reference to the drawings.

First, a description is given of a secondary battery according to an embodiment of the technology. Note that a negative electrode for a secondary battery according to an embodiment of the technology (hereinafter simply referred to as a “negative electrode”) is a part or one component of the secondary battery described here, and is thus described together below.

The secondary battery described here is a secondary battery that obtains a battery capacity by utilizing insertion and extraction of an electrode reactant. The secondary battery includes a positive electrode, a negative electrode, and an electrolyte.

In the secondary battery, a charge capacity of the negative electrode is greater than a discharge capacity of the positive electrode in order to prevent accidental precipitation of the electrode reactant on a surface of the negative electrode in the middle of charging. In other words, an electrochemical capacity per unit area of the negative electrode is set to be greater than an electrochemical capacity per unit area of the positive electrode.

The electrode reactant is not limited to a particular kind and may be a light metal such as an alkali metal or an alkaline earth metal. In the following, a description is given of an example case where the electrode reactant is lithium. A secondary battery that utilizes insertion and extraction of lithium serving as the electrode reactant is a so-called lithium-ion secondary battery.

First, a secondary battery of a laminated-film type (a so-called laminated cell) is described. The secondary battery of the laminated-film type includes an outer package member having softness or flexibility, that is, an outer package film 20 as an outer package member for containing a battery device.

FIG. 1 is a perspective view of a configuration of the secondary battery of the laminated-film type. FIG. 2 illustrates a sectional configuration of a wound electrode body 10 illustrated in FIG. 1 . FIG. 3 illustrates a plan configuration of each of a positive electrode 11 and a negative electrode 12 illustrated in FIG. 2 .

Note that FIG. 1 illustrates a state where the wound electrode body 10 and the outer package film 20 are separated away from each other. FIG. 2 illustrates only a portion of the wound electrode body 10 . FIG. 3 illustrates a state where the positive electrode 11 and the negative electrode 12 are separated away from each other. In FIG. 3 , the positive electrode 11 and the negative electrode 12 are each reduced in size in a longitudinal direction.

As illustrated in FIG. 1 , the secondary battery has the outer package film 20 having a pouch-shape in which a battery device of a wound type (the wound electrode body 10 ) is contained. A positive electrode lead 14 and a negative electrode lead 15 are coupled to the wound electrode body 10 . The positive electrode lead 14 and the negative electrode lead 15 are each led out from inside to outside the outer package film 20 in a similar direction.

The outer package film 20 is a single film foldable in a direction of an arrow R indicated by a dash-dot-dash line illustrated in FIG. 1 . The <figure-callout id="20" label="outer package film" filenames="US20220246979A1-20220804-D00001.png,US20220246979A1-20220804-D00006.png" st

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of PCT patent application no. PCT/JP2020/039452, filed on Oct. 21, 2020, which claims priority to Japanese patent application no. JP2019-195409, filed on Oct. 28, 2019, the entire contents of which are being incorporated herein by reference.

BACKGROUND

The present technology relates to a negative electrode for a secondary battery, and a secondary battery.

Various kinds of electronic equipment, including mobile phones, have been widely used. Such widespread use has promoted the development of a secondary battery that is smaller in size and lighter in weight and allows for a higher energy density, as a power source. The secondary battery includes a positive electrode, a negative electrode, and an electrolytic solution. The negative electrode includes a negative electrode active material and a negative electrode binder.

A configuration of the secondary battery influences a battery characteristic. Accordingly, the configuration of the secondary battery has been considered in various ways. For example, silicon monoxide is used as the negative electrode active material, and a single-walled carbon nanotube is used as a negative electrode conductor in order to obtain, for example, sufficient charge and discharge capacities. Further, a negative electrode active material which includes composite particles and carbon nanotubes is used in order to obtain, for example, a superior lifetime characteristic. The carbon nanotubes in the negative electrode active material are directly grown on surfaces of the composite particles that include, for example, silicon and natural graphite.

SUMMARY

The present application relates to a negative electrode for a secondary battery, and a secondary battery.

Consideration has been given in various ways to solve problems of the secondary battery; however, a battery capacity characteristic, an electric resistance characteristic, and a cyclability characteristic of the secondary battery each still remain insufficient. Accordingly, there is still room for improvement in terms of those characteristics.

The present technology has been made in view of such an issue, and is directed to providing a negative electrode for a secondary battery, and a secondary battery that are each able to increase the battery capacity and improve the electric resistance characteristic, the cyclability characteristic, or both according to an embodiment.

A negative electrode for a secondary battery according to an embodiment of the technology includes a silicon-containing material and a plurality of single-walled carbon nanotubes. The single-walled carbon nanotubes have a maximum outer diameter of 5 nm or less.

A secondary battery according to an embodiment of the technology includes a positive electrode, an electrolytic solution, and a negative electrode. The negative electrode includes a configuration similar to the configuration of the negative electrode for the secondary battery according to an embodiment of the technology described above.

The term “silicon-containing material” used herein is a generic term for a material including silicon (Si) as a constituent element. Thus, the silicon-containing material may be a simple substance of silicon, a compound of silicon, an alloy of silicon, or a mixture of two or more thereof.

According to the negative electrode for the secondary battery or the secondary battery of an embodiment of the technology, the negative electrode includes the silicon-containing material and the plurality of single-walled carbon nanotubes. The single-walled carbon nanotubes have a maximum outer diameter of 5 nm or less. Accordingly, it is possible to increase the battery capacity and improve the electric resistance characteristic, the cyclability characteristic, or both.

Note that effects of the technology are not necessarily limited to the effects described above and may include any of a series of suitable effects including described below in relation to the technology.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a perspective view of a configuration of a secondary battery of a laminated-film type according to an embodiment of the technology.

FIG. 2 is a sectional view of a configuration of a wound electrode body illustrated in FIG. 1 .

FIG. 3 is a plan view of a configuration of each of a positive electrode and a negative electrode illustrated in FIG. 2 .

FIG. 4 is a plan view for describing an orientation of a negative electrode conductor in the secondary battery according to an embodiment of the technology.

FIG. 5 is a plan view for describing an orientation of the negative electrode conductor in a first comparative example.

FIG. 6 is a plan view for describing an orientation of the negative electrode conductor in a second comparative example.

FIG. 7 is a flowchart for describing a procedure for preparing a negative electrode mixture slurry.

FIG. 8 is a sectional view of a configuration of another secondary battery of a cylindrical type according to an embodiment of the technology.

FIG. 9 is a perspective view of a configuration of a secondary battery of another laminated-film type according to a modification according to an embodiment.

FIG. 10 is a sectional view of a configuration of a stacked electrode body illustrated in FIG. 9 .

FIG. 11 is a block diagram illustrating a configuration of an application example of the secondary battery, which is a battery pack including a single battery.

FIG. 12 is a block diagram illustrating a configuration of an application example of the secondary battery, which is a battery pack including an assembled battery.

FIG. 13 is a block diagram illustrating a configuration of an application example of the secondary battery, which is an electric vehicle.

FIG. 14 illustrates a RBM spectrum and a five-point average differential spectrum of a negative electrode active material layer in Experiment example 3 in which the negative electrode conductor was single-walled carbon nanotubes, the negative electrode conductor was introduced at earlier introduction, and no five-point average differential peak was detected.

FIG. 15 illustrates a RBM spectrum and a five-point average differential spectrum of a negative electrode active material layer in Experiment example 2 in which the negative electrode conductor was single-walled carbon nanotubes, the negative electrode conductor was introduced at later introduction, and a five-point average differential peak was detected.

FIG. 16 illustrates a RBM spectrum and a five-point average differential spectrum of a single-walled carbon nanotube in which a five-point average differential peak was detected.

FIG. 17 illustrates a RBM spectrum and a five-point average differential spectrum of a negative electrode active material layer in a reference example in which no negative electrode conductor was introduced and no five-point average differential peak was detected.

DETAILED DESCRIPTION

One or more embodiments of the present technology are described below in detail with reference to the drawings.

First, a description is given of a secondary battery according to an embodiment of the technology. Note that a negative electrode for a secondary battery according to an embodiment of the technology (hereinafter simply referred to as a “negative electrode”) is a part or one component of the secondary battery described here, and is thus described together below.

The secondary battery described here is a secondary battery that obtains a battery capacity by utilizing insertion and extraction of an electrode reactant. The secondary battery includes a positive electrode, a negative electrode, and an electrolyte.

In the secondary battery, a charge capacity of the negative electrode is greater than a discharge capacity of the positive electrode in order to prevent accidental precipitation of the electrode reactant on a surface of the negative electrode in the middle of charging. In other words, an electrochemical capacity per unit area of the negative electrode is set to be greater than an electrochemical capacity per unit area of the positive electrode.

The electrode reactant is not limited to a particular kind and may be a light metal such as an alkali metal or an alkaline earth metal. In the following, a description is given of an example case where the electrode reactant is lithium. A secondary battery that utilizes insertion and extraction of lithium serving as the electrode reactant is a so-called lithium-ion secondary battery.

First, a secondary battery of a laminated-film type (a so-called laminated cell) is described. The secondary battery of the laminated-film type includes an outer package member having softness or flexibility, that is, an outer package film 20 as an outer package member for containing a battery device.

FIG. 1 is a perspective view of a configuration of the secondary battery of the laminated-film type. FIG. 2 illustrates a sectional configuration of a wound electrode body 10 illustrated in FIG. 1 . FIG. 3 illustrates a plan configuration of each of a positive electrode 11 and a negative electrode 12 illustrated in FIG. 2 .

Note that FIG. 1 illustrates a state where the wound electrode body 10 and the outer package film 20 are separated away from each other. FIG. 2 illustrates only a portion of the wound electrode body 10 . FIG. 3 illustrates a state where the positive electrode 11 and the negative electrode 12 are separated away from each other. In FIG. 3 , the positive electrode 11 and the negative electrode 12 are each reduced in size in a longitudinal direction.

As illustrated in FIG. 1 , the secondary battery has the outer package film 20 having a pouch-shape in which a battery device of a wound type (the wound electrode body 10 ) is contained. A positive electrode lead 14 and a negative electrode lead 15 are coupled to the wound electrode body 10 . The positive electrode lead 14 and the negative electrode lead 15 are each led out from inside to outside the outer package film 20 in a similar direction.

The outer package film 20 is a single film foldable in a direction of an arrow R indicated by a dash-dot-dash line illustrated in FIG. 1 . The outer package film 20 has a depression 20 U. The depression 20 U is a so-called deep drawn part designed to contain the wound electrode body 10 therein.

Specifically, the outer package film 20 is a laminated film including three layers: a fusion-bonding layer, a metal layer, and a surface protective layer that are laminated in this order from an inner side. In a state where the outer package film 20 is folded in the direction of the arrow R, the outer edges of the fusion-bonding layer are fusion-bonded to each other. The fusion-bonding layer includes a polymer compound such as polypropylene. The metal layer includes a metal material such as aluminum. The surface protective layer includes a polymer compound such as nylon. Note that the number of layers laminated into the outer package film 20 is not limited to three. The outer package film 20 may include one layer (a single layer), two layers, or four or more layers.

A sealing film 21 is interposed between the outer package film 20 and the positive electrode lead 14 , and a sealing film 22 is interposed between the outer package film 20 and the negative electrode lead 15 . The sealing films

21 and 22 are members for preventing outside air from entering. The sealing films

21 and 22 include, without limitation, a polyolefin resin having adherence to the positive electrode lead 14 and the negative electrode lead 15 . Examples of the polyolefin resin include polyethylene, polypropylene, modified polyethylene, and modified polypropylene. Note that the sealing film 21 , the sealing film 22 , or both may be omitted.

As illustrated in FIGS. 1 and 2 , the wound electrode body 10 includes the positive electrode 11 , the negative electrode 12 , a separator 13 , and an electrolytic solution. The electrolytic solution is a liquid electrolyte. In the wound electrode body 10 , the positive electrode 11 and the negative electrode 12 are stacked on each other with the separator 13 interposed therebetween, and the stack of the positive electrode 11 , the negative electrode 12 , and the separator 13 is wound. The positive electrode 11 , the negative electrode 12 , and the separator 13 are each impregnated with the electrolytic solution.

As illustrated in FIG. 2 , the positive electrode 11 includes a positive electrode current collector 11 A, and two positive electrode active material layers 11 B provided on respective opposite sides of the positive electrode current collector 11 A. However, the positive electrode active material layer 11 B may be provided on only one of the opposite sides of the positive electrode current collector 11 A.

The positive electrode current collector 11 A includes one or more of electrically conductive materials including, without limitation, aluminum, nickel, and stainless steel. The positive electrode active material layer 11 B includes one or more of positive electrode active materials into which lithium is insertable and from which lithium is extractable. The positive electrode active material layer 11 B may further include a material such as a positive electrode binder or a positive electrode conductor.

Although the positive electrode active material is not limited to a particular kind, the positive electrode active material is a lithium-containing compound such as a lithium-containing transition metal compound. The lithium-containing transition metal compound includes lithium and one or more of transition metal elements, and may further include one or more of other elements. The other elements are not limited to particular kinds as long as they are one or more of any elements excluding a transition metal element. In particular, it is preferable that the other elements be elements belonging to Groups 2 to 15 in the long period periodic table. Note that the lithium-containing transition metal compound may be an oxide, or may be, for example, one of a phosphoric acid compound, a silicic acid compound, or a boric acid compound.

Specific examples of the oxide include LiNiO 2 , LiCoO 2 , LiCo 0.98 Al 0.01 Mg 0.01 O 2 , LiNi 0.5 Co 0.2 Mn 0.3 O 2 , LiNi 0.8 Co 0.15 Al 0.05 O 2 , LiNi 0.33 Co 0.33 Mn 0.33 O 2 , Li 1.2 Mn 0.52 Co 0.175 Ni 0.1 O 2 , Li 1.15 (Mn 0.65 Ni 0.22 Co 0.13 )O 2 , and LiMn 2 O 4 . Specific examples of the phosphoric acid compound include LiFePO 4 , LiMnPO 4 , LiFe 0.5 Mn 0.5 PO 4 , and LiFe 0.3 Mn 0.7 PO 4 .

The positive electrode binder includes one or more of materials including, without limitation, a synthetic rubber and a polymer compound. Examples of the synthetic rubber include a styrene-butadiene-based rubber, a fluorine-based rubber, and ethylene propylene diene. Examples of the polymer compound include polyvinylidene difluoride and polyimide.

The positive electrode conductor includes an electrically conductive material such as a carbon material. Examples of the carbon material include graphite, carbon black, acetylene black, and Ketjen black. The positive electrode conductor may be a material such as a metal material or an electrically conductive polymer as long as the material has an electrically conductive property.

The positive electrode active material layer 11 B is provided on a portion of the positive electrode current collector 11 A on one side of the positive electrode current collector 11 A. Accordingly, a portion of the positive electrode current collector 11 A on which the positive electrode active material layer 11 B is not provided is exposed without being covered with the positive electrode active material layer 11 B.

Specifically, as illustrated in FIG. 3 , the positive electrode current collector 11 A extends in a longitudinal direction (X-axis direction) and includes a covered portion 11 AX and paired uncovered portions 11 AY. The covered portion 11 AX is a portion which is located at the middle portion of the positive electrode current collector 11 A in the longitudinal direction and on which the positive electrode active material layer 11 B is formed. The paired uncovered portions 11 AY are portions which are located at respective ends of the positive electrode current collector 11 A in the longitudinal direction and on which the positive electrode active material layer 11 B is not formed. Accordingly, the covered portion 11 AX is covered with the positive electrode active material layer 11 B, whereas the paired uncovered portions 11 AY are exposed without being covered with the positive electrode active material layer 11 B. In FIG. 3 , the positive electrode active material layer 11 B is slightly shaded.

As illustrated in FIG. 2 , the negative electrode 12 includes a negative electrode current collector 12 A, and two negative electrode active material layers 12 B provided on respective opposite sides of the negative electrode current collector 12 A. However, the negative electrode active material layer 12 B may be provided only on one of the opposite sides of the negative electrode current collector 12 A.

The negative electrode current collector 12 A includes one or more of electrically conductive materials including, without limitation, copper, aluminum, nickel, and stainless steel. The negative electrode active material layer 12 B includes a negative electrode active material into which lithium is insertable and from which lithium is extractable, and a negative electrode conductor. The negative electrode active material layer 12 B may further include materials including, without limitation, a negative electrode binder.

The negative electrode active material includes a silicon-containing material. A reason for this is that a high theoretical capacity (i.e., battery capacity) is obtained.

As described above, the term “silicon-containing material” is a generic term for a material including silicon as a constituent element. The silicon-containing material may be a simple substance of silicon, a compound of silicon, an alloy of silicon, or a mixture of two or more thereof. Specific examples of the alloy of silicon and the compound of silicon include SiB 4 , SiB 6 , Mg 2 Si, Ni 2 Si, TiSi 2 , MoSi 2 , CoSi 2 , NiSi 2 , CaSi 2 , CrSi 2 , Cu 5 Si, FeSi 2 , MnSi 2 , NbSi 2 , TaSi 2 , VSi 2 , WSi 2 , ZnSi 2 , SiC, Si 3 N 4 , Si 2 N 2 O, SiO v (0&lt;v&lt;2), and LiSiO. Note that the range of v may be 0.2&lt;v&lt;1.4.

It is preferable, in particular, the silicon-containing material include silicon oxide represented by SiO v (0&lt;v&lt;2) described above. It is more preferable that the silicon-containing material include SiO. A reason for this is that the amount of expansion or contraction at the time of charging and discharging is relatively small.

The negative electrode active material may further include one or more of other materials including, without limitation, a carbon-containing material and a metal-based material. Note that the silicon-containing material described above is excluded from the metal-based material described here.

The term “carbon-containing material” is a generic term for a material including carbon as a constituent element. Note that a material including both silicon and carbon as constituent elements shall be classified as the silicon-containing material, not as the carbon material. Additionally, the negative electrode conductor (single-walled carbon nanotubes) described below shall be excluded from the carbon-containing material described here. Specific examples of the carbon-containing material include graphitizable carbon, non-graphitizable carbon, and graphite. The graphite may be natural graphite, artificial graphite, or both. The graphite is a carbon material having an average interplanar spacing d002 of less than 0.34 nm. The graphitizable carbon is a carbon material having an average interplanar spacing d002 of 0.34 nm or greater and 0.36 nm or less. The non-graphitizable carbon is a carbon material having an average interplanar spacing d002 of 0.37 nm or greater.

It is preferable, in particular, that the carbon-containing material include graphite in order to increase the battery capacity and in order to form an electrically conductive network. Further, it is preferable that the carbon-containing material include a material that includes graphite particles of which surfaces are covered with a covering material, that is, covered particles, in order to reduce reactivity of the surface of the graphite to the electrolytic solution. The covering material includes one or more of materials including, without limitation, graphitizable carbon and non-graphitizable carbon. The thickness of the covering material is not limited to a particular thickness. However, it is preferable, in particular, that the thickness of the covering material be 10% or less of the radius of the covered particle, i.e., 10% or less of the distance from the surface of the covered particle to the center of the covered particle.

The term “metal-based material” is a generic term for a material that includes one or more of metal elements and metalloid elements that are each able to form an alloy with lithium, as a constituent element or constituent elements. The metal-based material may thus be a simple substance, an alloy, a compound, or a mixture of two or more thereof. The metal-based material may include one or more of non-metallic elements. Specific examples of the metal element and the metalloid element include tin.

It is preferable, in particular, that the negative electrode active material include the carbon-containing material together with the silicon-containing material. A reason for this is that expansion or contraction of the negative electrode active material layer 12 B is reduced at the time of charging and discharging while a high battery capacity is secured, as compared with a case where the negative electrode active material includes only the silicon-containing material.

The negative electrode conductor includes single carbon nanotubes, which are carbon substances each having a fiber shape (a tubular shape), i.e., so-called single-walled carbon nanotubes (SWCNT). Thus, the negative electrode active material layer 12 B includes the single-walled carbon nanotubes serving as the negative electrode conductor, together with the silicon-containing material serving as the negative electrode active material. A reason for this is that, in a case where the negative electrode active material is in the form of particles, the particles of the negative electrode active material are electrically coupled to each other via the single-walled carbon nanotubes. This increases electron conductivity between the particles of the negative electrode active material, resulting in an increase in electrical conductivity of the negative electrode active material layer 12 B.

The number of the single-walled carbon nanotubes per unit weight is greater than the number of multi-walled carbon nanotubes (MWCNT) per unit weight. Accordingly, using the single-walled carbon nanotubes as the negative electrode conductor sufficiently increases the electrical conductivity of the negative electrode active material layer 12 B.

The negative electrode conductor may further include the multi-walled carbon nanotubes described above in addition to the single-walled carbon nanotubes. The multi-walled carbon nanotubes encompass nanotubes including double-walled (DW) carbon nanotubes.

The single-walled carbon nanotubes have a maximum outer diameter of 5 nm or less. That is, although the outer diameter (thickness) of each of the single-walled carbon nanotubes is not limited to a particular outer diameter, a maximum value of the outer diameters of the single-walled carbon nanotubes is 5 nm or less. Note that, the single-walled carbon nanotubes each have an outer diameter of approximately 1 nm to approximately 2 nm. The double-walled carbon nanotubes each have an outer diameter of approximately 5 nm to approximately 6 nm. The multi-walled carbon nanotubes each have an outer diameter of 10 nm to 200 nm both inclusive.

A reason for this is that the dispersibility of the single-walled carbon nanotubes in the negative electrode active material layer 12 B is secured and the particles of the negative electrode active material are thus easily electrically coupled to each other via the single-walled carbon nanotubes. This markedly increases the electron conductivity between the particles of the negative electrode material, and thus markedly increases the electrical conductivity of the negative electrode active material layer 12 B, as compared with a case where the dispersibility of the single-walled carbon nanotubes in the negative electrode active material layer 12 B is insufficient.

That is, in the case where the dispersibility of the single-walled carbon nanotubes in the negative electrode active material layer 12 B is insufficient, the single-walled carbon nanotubes are easily entangled with each other. This causes the outer diameter of the single-walled carbon nanotubes to increase easily, resulting in a maximum outer diameter of greater than 5 nm. In contrast, in a case where the dispersibility of the single-walled carbon nanotubes in the negative electrode active material layer 12 B is sufficient, the single-walled carbon nanotubes are prevented from being easily entangled with each other. This helps to prevent an increase in the outer diameter of the single-walled carbon nanotubes, resulting in a maximum outer diameter of 5 nm or less.

The maximum outer diameter of the single-walled carbon nanotubes is determined as follows. First, the negative electrode active material layer 12 B is observed with a microscope such as a scanning electron microscope (SEM). Thereafter, the outer diameter of the single-walled carbon nanotube is measured at ten different points on the basis of the result of observation (a micrograph) of the negative electrode active material layer 12 B. Lastly, a maximum value is identified from the outer diameters measured at the ten points, and is set as the maximum outer diameter.

For the secondary battery described here, it is preferable that a physical property (the presence or absence of a five-point average differential peak described below) of the negative electrode 12 be properly controlled by controlling the orientation of the negative electrode conductor (the single-walled carbon nanotubes) into an appropriate state in order to further increase the electrical conductivity of the negative electrode 12 (the negative electrode active material layer 12 B). The physical property of the negative electrode 12 is to be described in detail later.

The content of the negative electrode conductor (the single-walled carbon nanotubes) in the negative electrode active material layer 12 B is not limited to a particular content. However, it is preferable, in particular, that the content of the negative electrode conductor (the single-walled carbon nanotubes) be 0.01 wt % to 0.03 wt % both inclusive. A reason for this is that the single-walled carbon nanotubes are prevented from being easily entangled with each other, and it thus becomes easier to control the orientations of the single-walled carbon nanotubes into appropriate states.

The negative electrode active material layer 12 B is provided over the entire negative electrode current collector 12 A on one side of the negative electrode current collector 12 A. Accordingly, the negative electrode current collector 12 A is entirely covered with the negative electrode active material layer 12 B without being exposed.

Specifically, as illustrated in FIG. 3 , the negative electrode current collector 12 A extends in the longitudinal direction (X-axis direction), and the negative electrode active material layer 12 B includes paired unopposed portions 12 BZ. The paired unopposed portions 12 BZ are opposed to the paired uncovered portions 11 AY. That is, the paired unopposed portions 12 BZ are not opposed to the positive electrode active material layer 11 B and thus do not contribute to charging and discharging reactions. In FIG. 3 , the negative electrode active material layer 12 B is darkly shaded.

The negative electrode active material layer 12 B is entirely provided on the negative electrode current collector 12 A, whereas the positive electrode active material layer 11 B is provided on only a portion (the covered portion 11 AX) of the positive electrode current collector 11 A, in order to prevent lithium extracted from the positive electrode active material layer 11 B at the time of charging from precipitating on the surface of the negative electrode 12 .

As illustrated in FIG. 2 , the separator 13 is interposed between the positive electrode 11 and the negative electrode 12 . The separator 13 allows lithium to pass therethrough while preventing short circuiting between the positive electrode 11 and the negative electrode 12 caused by contact between the positive electrode 11 and the <figure-callout id="12" label="negati

CLAIMS

Claims ( 8 )

1 . A secondary battery comprising:

a positive electrode; a negative electrode including a silicon-containing material and a plurality of single-walled carbon nanotubes, the plurality of single-walled carbon nanotubes having a maximum outer diameter of 5 nanometers or less; and an electrolytic solution.

2 . The secondary battery according to claim 1 , wherein

the negative electrode includes a negative electrode active material layer, the negative electrode active material layer including the silicon-containing material and the plurality of single-walled carbon nanotubes, and a peak is detected in a range of Raman shift of 165 cm −1 or greater and 185 cm −1 or less in five-point average differentiation of a Raman spectrum of the negative electrode active material layer in a radial breathing mode, the Raman spectrum being measured by Raman spectroscopy.

3 . The secondary battery according to claim 1 , wherein the silicon-containing material includes silicon oxide represented by SiO v where v is greater than 0 and less than 2.

4 . The secondary battery according to claim 1 , wherein the negative electrode further includes a carbon-containing material.

5 . A negative electrode for a secondary battery, the negative electrode comprising:

a silicon-containing material; and a plurality of single-walled carbon nanotubes, the plurality of single-walled carbon nanotubes having a maximum outer diameter of 5 nanometers or less.

6 . The negative electrode according to claim 5 , wherein

the negative electrode includes a negative electrode active material layer, the negative electrode active material layer including the silicon-containing material and the plurality of single-walled carbon nanotubes, and a peak is detected in a range of Raman shift of 165 cm −1 or greater and 185 cm −1 or less in five-point average differentiation of a Raman spectrum of the negative electrode active material layer in a radial breathing mode, the Raman spectrum being measured by Raman spectroscopy.

7 . The negative electrode according to claim 5 , wherein the silicon-containing material includes silicon oxide represented by SiO v where v is greater than 0 and less than 2.

8 . The negative electrode according to claim 5 , wherein the negative electrode further includes a carbon-containing material.

US17/723,861

2019-10-28

2022-04-19

Negative electrode for secondary battery, and secondary battery

Active

2042-01-08

US12597633B2

( en )

Applications Claiming Priority (3)

Application Number

Priority Date

Filing Date

Title

JP2019-195409

2019-10-28

JP2019195409

2019-10-28

PCT/JP2020/039482

WO2021085255A1

( en )

2019-10-28

2020-10-21

Secondary battery negative electrode and secondary battery

Related Parent Applications (1)

Application Number

Title

Priority Date

Filing Date

PCT/JP2020/039482

Continuation

WO2021085255A1

( en )

2019-10-28

2020-10-21

Secondary battery negative electrode and secondary battery

Publications (2)

Publication Number

Publication Date

US20220246979A1

true

US20220246979A1 ( en )

2022-08-04

US12597633B2

US12597633B2 ( en )

2026-04-07

Family

ID=75715112

Family Applications (1)

Application Number

Title

Priority Date

Filing Date

US17/723,861

Active

2042-01-08

US12597633B2

( en )

2019-10-28

2022-04-19

Negative electrode for secondary battery, and secondary battery

Country Status (4)

Country

Link

US

( 1 )

US12597633B2

( en )

JP

( 1 )

JP7439834B2

( en )

CN

( 1 )

CN114641871A

( en )

WO

( 1 )

WO2021085255A1

( en )

Cited By (4)

* Cited by examiner, † Cited by third party

Publication number

Priority date

Publication date

Assignee

Title

US20230170527A1

( en )

*

2020-03-31

2023-06-01

Panasonic Intellectual Property Management Co., Ltd.

Nonaqueous electrolyte secondary battery

EP4322247A1

( en )

*

2022-08-09

2024-02-14

Prime Planet Energy &amp; Solutions, Inc.

Negative electrode and secondary battery including the same

EP4471891A4

( en )

*

2022-01-28

2025-10-08

Panasonic Energy Co Ltd

Negative electrode for a secondary battery with anhydrous electrolyte and secondary battery with anhydrous electrolyte

EP4641669A4

( en )

*

2023-02-24

2026-04-29

Nanjing Chervon Ind Co Ltd

SILICON-CARBON BATTERY, BATTERY PACK, ENERGY STORAGE DEVICE, POWER TOOL AND BATTERY PACK CHARGER

Families Citing this family (16)

* Cited by examiner, † Cited by third party

Publication number

Priority date

Publication date

Assignee

Title

JP7754160B2

( en )

*

2021-05-18

2025-10-15

株式会社村田製作所

Negative electrode for secondary battery and secondary battery

JP7732711B2

( en )

*

2021-08-13

2025-09-02

エルジー エナジー ソリューション リミテッド

Anode and secondary battery including said anode

JP2024520547A

( en )

*

2021-10-05

2024-05-24

エルジー エナジー ソリューション リミテッド

Lithium secondary battery

KR102894075B1

( en )

*

2021-11-01

2025-12-03

주식회사 엘지에너지솔루션

Negatvie electrode with single walled carbon nanotube and secondary battery comprising the same

JP2024512901A

( en )

*

2021-11-01

2024-03-21

エルジー エナジー ソリューション リミテッド

Negative electrode to which single-walled carbon nanotubes are applied and secondary battery containing the same

WO2023189682A1

( en )

*

2022-03-30

2023-10-05

パナソニックＩｐマネジメント株式会社

Non-aqueous electrolyte secondary battery

EP4447147A4

( en )

*

2022-10-21

2025-05-21

LG Energy Solution, Ltd.

Negative electrode composition, negative electrode for lithium secondary battery therewith, and lithium secondary battery with negative electrode

JP7671728B2

( en )

*

2022-12-13

2025-05-02

プライムプラネットエナジー＆ソリューションズ株式会社

Negative electrode for non-aqueous electrolyte secondary battery and method for producing same

CN120153486A

( en )

*

2023-01-13

2025-06-13

株式会社村田制作所

Negative electrode for secondary battery and secondary battery

JP2024141382A

( en )

*

2023-03-29

2024-10-10

株式会社Ａｅｓｃジャパン

Negative electrode for non-aqueous electrolyte secondary battery and non-aqueous electrolyte secondary battery using the same

JP2024141365A

( en )

*

2023-03-29

2024-10-10

株式会社Ａｅｓｃジャパン

Negative electrode for non-aqueous electrolyte secondary battery and non-aqueous electrolyte secondary battery using the same

JP2024141372A

( en )

*

2023-03-29

2024-10-10

株式会社Ａｅｓｃジャパン

Negative electrode for non-aqueous electrolyte secondary battery and non-aqueous electrolyte secondary battery using the same

JP2024141388A

( en )

*

2023-03-29

2024-10-10

株式会社Ａｅｓｃジャパン

Negative electrode for non-aqueous electrolyte secondary battery and non-aqueous electrolyte secondary battery using the same

JP2024141386A

( en )

*

2023-03-29

2024-10-10

株式会社Ａｅｓｃジャパン

Negative electrode for non-aqueous electrolyte secondary battery and non-aqueous electrolyte secondary battery using the same

JP7858604B2

( en )

*

2023-08-31

2026-05-14

プライムプラネットエナジー＆ソリューションズ株式会社

A negative electrode and its manufacturing method, and a non-aqueous electrolyte secondary battery containing a negative electrode and its manufacturing method.

WO2025205078A1

( en )

*

2024-03-28

2025-10-02

パナソニックＩｐマネジメント株式会社

Negative electrode for secondary battery, and secondary battery

Citations (4)

* Cited by examiner, † Cited by third party

Publication number

Priority date

Publication date

Assignee

Title

US20080170982A1

( en )

*

2004-11-09

2008-07-17

Board Of Regents, The University Of Texas System

Fabrication and Application of Nanofiber Ribbons and Sheets and Twisted and Non-Twisted Nanofiber Yarns

US20130189565A1

( en )

*

2008-05-07

2013-07-25

Nanocomp Technologies, Inc.

Batteries Having Nanostructured Composite Cathode

US20180198159A1

( en )

*

2015-07-09

2018-07-12

Nec Corporation

Lithium ion secondary battery

US20190237753A1

( en )

*

2018-01-31

2019-08-01

Gp Batteries International Limited

Anode active material and anode for lithium-ion battery, method for preparing the anode active material, and lithium-ion battery

Family Cites Families (14)

* Cited by examiner, † Cited by third party

Publication number

Priority date

Publication date

Assignee

Title

US9088049B2

( en )

*

2012-01-23

2015-07-21

Florida State University Research Foundation, Inc.

Bifunctional hollandite Ag2Mn8O16 catalyst for lithium-air batteries

WO2013147087A1

( en )

*

2012-03-28

2013-10-03

宇部興産株式会社

Fine carbon dispersion composition and polyimide/fine carbon composite using same

KR20150074903A

( en )

2013-12-24

2015-07-02

일진전기 주식회사

Cathode plate for lithium secondary battery

WO2015163017A1

( en )

*

2014-04-21

2015-10-29

ソニー株式会社

Secondary cell, cell pack, electric vehicle, electric power storage system, electric tool, and electronic device

EP3134932B1

( en )

2014-04-25

2021-08-25

South Dakota Board of Regents

High capacity electrodes

CN107210445B

( en )

*

2015-09-17

2021-03-16

积水化学工业株式会社

Binder for storage device electrodes

KR20170044360A

( en )

2015-10-15

2017-04-25

지에스에너지 주식회사

Anode active material for secondary battery and preparation method thereof

JP2017084759A

( en )

*

2015-10-30

2017-05-18

大阪瓦斯株式会社

Electrode active material-carbon nanotube composite and manufacturing method thereof

WO2017188021A1

( en )

2016-04-26

2017-11-02

日立マクセル株式会社

Electrochemical element electrode and lithium ion secondary battery

JP6908058B2

( en )

2017-02-09

2021-07-21

株式会社村田製作所

Rechargeable batteries, battery packs, electric vehicles, power tools and electronics

US20190036102A1

( en )

2017-07-31

2019-01-31

Honda Motor Co., Ltd.

Continuous production of binder and collector-less self-standing electrodes for li-ion batteries by using carbon nanotubes as an additive

JP7059873B2

( en )

2017-12-19

2022-04-26

東洋インキＳｃホールディングス株式会社

Conductive compositions, and conductive films

CN108461804A

( en )

*

2018-01-31

2018-08-28

深圳市卓能新能源股份有限公司

A 18650-3800mAh lithium battery and its preparation method

CN108878855A

( en )

*

2018-07-23

2018-11-23

桑德集团有限公司

Silicon-carbon cathode material, silicon-carbon cathode, lithium ion battery and electric vehicle

2020

2020-10-21

WO

PCT/JP2020/039482

patent/WO2021085255A1/en

not_active

Ceased

2020-10-21

JP

JP2021553478A

patent/JP7439834B2/en

active

Active

2020-10-21

CN

CN202080075205.XA

patent/CN114641871A/en

active

Pending

2022

2022-04-19

US

US17/723,861

patent/US12597633B2/en

active

Active

Patent Citations (4)

* Cited by examiner, † Cited by third party

Publication number

Priority date

Publication date

Assignee

Title

US20080170982A1

( en )

*

2004-11-09

2008-07-17

Board Of Regents, The University Of Texas System

Fabrication and Application of Nanofiber Ribbons and Sheets and Twisted and Non-Twisted Nanofiber Yarns

US20130189565A1

( en )

*

2008-05-07

2013-07-25

Nanocomp Technologies, Inc.

Batteries Having Nanostructured Composite Cathode

US20180198159A1

( en )

*

2015-07-09

2018-07-12

Nec Corporation

Lithium ion secondary battery

US20190237753A1

( en )

*

2018-01-31

2019-08-01

Gp Batteries International Limited

Anode active material and anode for lithium-ion battery, method for preparing the anode active material, and lithium-ion battery

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party

Title

" Carbon Nanotubes--the Route Toward Applications ", Baughman et al., Science 297, 787, P787 - 792. August 2, 2002.

*

Cited By (4)

* Cited by examiner, † Cited by third party

Publication number

Priority date

Publication date

Assignee

Title

US20230170527A1

( en )

*

2020-03-31

2023-06-01

Panasonic Intellectual Property Management Co., Ltd.

Nonaqueous electrolyte secondary battery

EP4471891A4

( en )

*

2022-01-28

2025-10-08

Panasonic Energy Co Ltd

Negative electrode for a secondary battery with anhydrous electrolyte and secondary battery with anhydrous electrolyte

EP4322247A1

( en )

*

2022-08-09

2024-02-14

Prime Planet Energy &amp; Solutions, Inc.

Negative electrode and secondary battery including the same

EP4641669A4

( en )

*

2023-02-24

2026-04-29

Nanjing Chervon Ind Co Ltd

SILICON-CARBON BATTERY, BATTERY PACK, ENERGY STORAGE DEVICE, POWER TOOL AND BATTERY PACK CHARGER

Also Published As

Publication number

Publication date

WO2021085255A1

( en )

2021-05-06

CN114641871A

( en )

2022-06-17

JPWO2021085255A1

( en )

2021-05-06

JP7439834B2

( en )

2024-02-28

US12597633B2

( en )

2026-04-07

Similar Documents

Publication

Publication Date

Title

US12597633B2

( en )

2026-04-07

Negative electrode for secondary battery, and secondary battery

US11329277B2

( en )

2022-05-10

Secondary battery, battery pack, electrically driven vehicle, electric power storage system, electric tool, and electronic device

CN102292863B

( en )

2014-05-07

Method for determining completion of charging and discharging of lithium-ion secondary battery, charge control circuit, discharge control circuit, and power supply

JPWO2019022044A1

( en )

2020-07-02

Negative electrode for secondary battery, secondary battery, battery pack, electric vehicle, power storage system, power tool and electronic device

US12424622B2

( en )

2025-09-23

Secondary battery

US12206109B2

( en )

2025-01-21

Active material, method of manufacturing the same, electrode, and secondary battery

US12040480B2

( en )

2024-07-16

Secondary battery

US20240097127A1

( en )

2024-03-21

Negative electrode for secondary battery, and secondary battery

US12603279B2

( en )

2026-04-14

Positive electrode active material for secondary battery, positive electrode for secondary battery, and secondary battery

US20230025122A1

( en )

2023-01-26

Secondary battery

WO2023063008A1

( en )

2023-04-20

Secondary battery

US20240047829A1

( en )

2024-02-08

Secondary battery

US20220223873A1

( en )

2022-07-14

Negative electrode for secondary battery, and secondary battery

US12334505B2

( en )

2025-06-17

Secondary battery

US20220255169A1

( en )

2022-08-11

Secondary battery and battery pack

JP7302731B2

( en )

2023-07-04

secondary battery

WO2023286579A1

( en )

2023-01-19

Negative electrode for secondary batteries, and secondary battery

WO2023120688A1

( en )

2023-06-29

Secondary battery

WO2021187068A1

( en )

2021-09-23

Secondary cell

US20250391908A1

( en )

2025-12-25

Positive electrode for secondary battery and secondary battery

US12424654B2

( en )

2025-09-23

Secondary battery

US12451518B2

( en )

2025-10-21

Secondary battery having a film covering a negative active material layer

US20230207792A1

( en )

2023-06-29

Negative electrode for secondary battery, and secondary battery

US20240372097A1

( en )

2024-11-07

Negative electrode for secondary battery, and secondary battery

US20250273653A1

( en )

2025-08-28

Negative electrode for secondary battery, and secondary battery

Legal Events

Date

Code

Title

Description

2022-04-19

AS

Assignment

Owner name : MURATA MANUFACTURING CO., LTD., JAPAN

Free format text : ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:ONUMA, AMI;HAYAZAKI, SHINJI;SIGNING DATES FROM 20220407 TO 20220412;REEL/FRAME:059639/0621

2022-04-19

FEPP

Fee payment procedure

Free format text : ENTITY STATUS SET TO UNDISCOUNTED (ORIGINAL EVENT CODE: BIG.); ENTITY STATUS OF PATENT OWNER: LARGE ENTITY

2022-05-16

STPP

Information on status: patent application and granting procedure in general

Free format text : DOCKETED NEW CASE - READY FOR EXAMINATION

2024-09-23

STPP

Information on status: patent application and granting procedure in general

Free format text : NON FINAL ACTION MAILED

2024-11-12

STPP

Information on status: patent application and granting procedure in general

Free format text : RESPONSE TO NON-FINAL OFFICE ACTION ENTERED AND FORWARDED TO EXAMINER

2025-01-28

STPP

Information on status: patent application and granting procedure in general

Free format text : FINAL REJECTION MAILED

2025-07-16

STPP

Information on status: patent application and granting procedure in general

Free format text : RESPONSE TO NON-FINAL OFFICE ACTION ENTERED AND FORWARDED TO EXAMINER

2025-08-24

STPP

Information on status: patent application and granting procedure in general

Free format text : FINAL REJECTION COUNTED, NOT YET MAILED

2025-08-26

STPP

Information on status: patent application and granting procedure in general

Free format text : FINAL REJECTION MAILED

2025-08-27

STPP

Information on status: patent application and granting procedure in general

Free format text : FINAL REJECTION MAILED

2026-01-22

STPP

Information on status: patent application and granting procedure in general

Free format text : DOCKETED NEW CASE - READY FOR EXAMINATION

Free format text : ALLOWED -- NOTICE OF ALLOWANCE NOT YET MAILED

2026-02-12

STPP

Information on status: patent application and granting procedure in general

Free format text : ALLOWED -- NOTICE OF ALLOWANCE NOT YET MAILED

2026-02-17

STPP

Information on status: patent application and granting procedure in general

Free format text : NOTICE OF ALLOWANCE MAILED -- APPLICATION RECEIVED IN OFFICE OF PUBLICATIONS

2026-03-11

STPP

Information on status: patent application and granting procedure in general

Free format text : PUBLICATIONS -- ISSUE FEE PAYMENT RECEIVED

Free format text : PUBLICATIONS -- ISSUE FEE PAYMENT VERIFIED

2026-03-25

STCF

Information on status: patent grant

Free format text : PATENTED CASE

Related documents

• Big data-based autonomous flight drone system and autonomous flight method … — Rgblab Co., Ltd. (US20210390867A1)#653964
• Generating augmented reality experiences utilizing physical objects to … — Meta Platforms Technologies, Llc (US20260037214A1)#653960
• Virtual reality system using multiple force arrays for a solver — DeepMotion, Inc. (US10657696B2)#653961
• Tracking position of device inside-out for virtual reality interactivity — Sony Interactive Entertainment America Llc (US10535153B2)#653962
• Augmented reality system with spatialized audio tied to user manipulated … — Magic Leap, Inc. (US11231770B2)#653963