Anode and secondary battery

Patent metadata

Field	Value
Publication number	US-9634330-B2
Application number	US-42851809-A
Country	US
Kind code	B2
Filing date	Apr 23, 2009
Priority date	Apr 23, 2008
Publication date	Apr 25, 2017
Grant date	Apr 25, 2017

Abstract

A secondary battery capable of improving the cycle characteristics is provided. The secondary battery includes a cathode, an anode, and an electrolytic solution. The electrolytic solution is impregnated in a separator provided between the cathode and the anode. The anode has an anode structure on an anode current collector. The anode structure has a structure in which a plurality of anode active material particles having silicon are held by a plurality of metal fibers forming a three-dimensional network structure. Due to the plurality of metal fibers, sufficient conductive paths are obtained among the plurality of anode active material particles. Thus, compared to a general anode in which an active material layer is provided on a current collector made of a metal foil or the like, the current collectivity is improved.

First claim

What is claimed is:

1. A secondary battery comprising:
a cathode;
an anode comprising (i) a plurality of metal fibers forming a conductive three-dimensional network structure, (ii) a resin binder securing the metal fibers in a sheet structure, and (iii) a plurality of anode active material particles having silicon (Si) at least a portion of which are contained within the three-dimensional network structure and which contact the metal fibers, and
an electrolytic solution,
wherein,
the sheet structure is uncompressed,
at least part of the resin binder is carbonized,
the metal fibers function as a current collector,
the anode, cathode and electrolytic solution are wound together and form a wound structure, each of the cathode and anode are elongated structures that extend along an anode-extending direction, where the anode-extending direction of the anode is defined by a length of the anode that is longer than a width of the anode,
the plurality of metal fibers (i) do not form an intermetallic compound with an electrode reactant, (ii) have a diameter D from 1 μm to 15 μm, both inclusive, and (iii) have a ratio B/A between average cross sectional diameter A and average length B of the metal fibers is 2 or more, at least some of the metal fibers extend more along the anode-extending direction than orthogonal to the anode-extending direction to form a conductive path along the anode-extending direction, these metal fibers being such that when each is divided into a component in the extending direction and a component in a direction orthogonal to the extending direction in a cross section along the extending direction of the anode, ratio Y/X between dimension X of the component in the extending direction and dimension Y of the component in the direction orthogonal to the extending direction is less than 1,
an amount of the anode active material particles contained within the three-dimensional network structure is greater than an amount of the anode active material particles located on a surface of the three-dimensional network structure or in a vicinity of the surface of the three-dimensional network structure,
the anode active material particles have a median diameter of 0.1 μm to 30 μm, both inclusive, and
the sheet structure has (i) a thickness from 10 μm to 200 μm, both inclusive, (ii) a porosity from 20% to 95% both inclusive, and (iii) a tensile strength of 0.1 N/mm or more.

2. The secondary battery according to claim 1 , wherein the plurality of metal fibers are connected to each other at least partially and thereby forming the three-dimensional network structure.

3. The secondary battery according to claim 1 , wherein the metal fibers are at least one selected from the group consisting of titanium (Ti), iron (Fe), stainless, copper (Cu), aluminum (Al), zinc (Zn), silver (Ag), cobalt (Co), nickel (Ni), and chromium (Cr).

4. The secondary battery according to claim 1 , wherein diameter D of the metal fibers is from 2 μm to 10 μm.

5. The secondary battery according to claim 1 , wherein the plurality of metal fibers form a sheet.

6. The secondary battery according to claim 1 , wherein the anode active material particles are a simple substance of silicon, a compound of silicon, an alloy of silicon, or any combination of them.

7. The secondary battery according to claim 1 , wherein a median size of the anode active material particles is from 1 μm to 20 μm both inclusive.

8. The secondary battery according to claim 1 , wherein the binder contains at least one resin selected from the group consisting of polyimide, polyamide, and polyamideimide.

9. The secondary battery according to claim 1 , wherein the anode contains an anode electrical conductor containing a carbon material.

10. The secondary battery according to claim 1 , wherein the anode includes an anode current collector and an arithmetic average roughness Ra of a surface of the anode current collector is 0.2 μm or more.

11. The secondary battery according to claim 1 , wherein the electrolytic solution contains a solvent containing at least one of a chain ester carbonate having halogen represented by Chemical formula 1, a cyclic ester carbonate having halogen represented by Chemical formula 2, a cyclic ester carbonate having an unsaturated bond represented by Chemical formula 3 to Chemical formula 5, sultone, and an acid anhydride:
Chemical formula 1

where R11 to R16 are a hydrogen group, a halogen group, an alkyl group, or an alkyl halide group, and at least one of R11 to R16 is the halogen group or the alkyl halide group;

where R17 to R20 are a hydrogen group, a halogen group, an alkyl group, or an alkyl halide group, and at least one of R17 to R20 is the halogen group or the alkyl halide group;

where R21 and R22 are a hydrogen group or an alkyl group;

where R23 to R26 are a hydrogen group, an alkyl group, a vinyl group, or an aryl group, and at least one of R23 to R26 is the vinyl group or the aryl group;

where R27 is an alkylene group.

12. The secondary battery according to claim 11 , wherein the chain ester carbonate having halogen represented by the Chemical formula 1 is fluoromethyl methyl carbonate, difluoromethyl methyl carbonate, or bis(fluoromethyl) carbonate, the cyclic ester carbonate having halogen represented by the Chemical formula 2 is 4-fluoro-1,3-dioxolane-2-one or 4,5-difluoro-1,3-dioxolane-2-one, the cyclic ester carbonate having an unsaturated bond represented by the Chemical formula 3 is vinylene carbonate, the cyclic ester carbonate having an unsaturated bond represented by the Chemical formula 4 is vinylethylene carbonate, and the cyclic ester carbonate having an unsaturated bond represented by the Chemical formula 5 is methylene ethylene carbonate.

13. The secondary battery according to claim 1 , wherein the electrolytic solution contains an electrolyte salt containing at least one selected from the group consisting of lithium hexafluorophosphate (LiPF 6 ), lithium tetrafluoroborate (LiBF 4 ), lithium perchlorate (LiClO 4 ), lithium hexafluoroarsenate (LiAsF 6 ), compounds represented by Chemical formula 6 to Chemical formula 8, and compounds represented by Chemical formula 9 to Chemical formula 11:

where X31 is a Group 1 element or a Group 2 element in the long period periodic table or aluminum (Al), M31 is a transition metal element, a Group 13 element, a Group 14 element, or a Group 15 element in the long period periodic table, R31 is a halogen group, Y31 is —(O═)C—R32-C(═O)—, —(O═)C—C(R33) 2 -, or —(O═)C—C(═O)—, R32 is an alkylene group, an alkylene halide group, an arylene group, or an arylene halide group, R33 is an alkyl group, an alkyl halide group, an aryl group, or an aryl halide group, a3 is one of integer numbers 1 to 4, b3 is 0, 2, or 4, and c3, d3, m3, and n3 are one of integer numbers 1 to 3;

where X41 is a Group 1 element or a Group 2 element in the long period periodic table, M41 is a transit

Assignees

• Hirose Takakazu
• Kawase Kenichi
• Takada Tomoo
• Noguchi Kazunori
• Fujii Takayuki
• Sony Corp

Inventors

• Hirose Takakazu
• Kawase Kenichi
• Takada Tomoo
• Noguchi Kazunori
• Fujii Takayuki

Classifications

• H01M4/621

  Binders · CPC title

• H01M10/0525

  Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries · CPC title

• H01M10/0587

  of accumulators having only wound construction elements, i.e. wound positive electrodes, wound negative electrodes and wound separators · CPC title

• H01M4/626

  Metals · CPC title

• H01M4/624 Primary

  Electric conductive fillers · CPC title