Binder resin for lithium secondary battery electrode, electrode for lithium secondary battery, and lithium secondary battery
Provided are a binder resin for an electrode of a lithium secondary battery containing a solvent-soluble polyimide having a repeating unit represented by the following Formula [I], and a method of producing the binder resin for an electrode. (In the formula, Z represents an aromatic or alicyclic tetracarboxylic dianhydride residue, and Ar is an aromatic diamine residue having a carboxyl group and an aromatic diamine residue having an aromatic ether bond, or an aromatic diamine residue having a phenylindan structure).
1. An electrode for a lithium secondary battery, which is formed by applying a mixture material of an active material, a binder resin for an electrode of a lithium secondary battery, said binder resin containing a solvent-soluble polyimide having a repeating unit represented by the following Formula [I]:
wherein in the formula, Z represents an aromatic or alicyclic tetracarboxylic dianhydride residue; and Ar is an aromatic diamine residue having a carboxyl group and an aromatic diamine residue having an aromatic ether bond, or an aromatic diamine residue having a phenylindan-structure, and a conductive material onto a current collector,
wherein the electrode is a negative electrode using a silicon-containing substance as the active material,
wherein in cases where Ar is the aromatic diamine residue having a carboxyl group and the aromatic diamine residue having an aromatic ether bond, the aromatic diamine component having a carboxyl group is from 27% by mole to 50% by mole of a total aromatic diamine component,
wherein the content of the binder resin based on the active material is from 10% by weight to 30% by weight in terms of the weight (solid content) of the polyimide, and
wherein the silicon-containing substance is silicon (Si) or silicon alloy.
2. The electrode according to claim 1 , wherein the content of the binder resin based on the active material is from 15% by weight to 30% by weight in terms of the weight (solid content) of the polyimide.
3. A lithium secondary battery comprising a negative electrode, a positive electrode, a separation membrane, an electrolyte, and an outer packaging material, wherein the positive electrode or the negative electrode is the electrode according to claim 1 .
4. The electrode according to claim 1 , wherein the solvent-soluble polyimide is a block copolymer having a repeating unit represented by the following Formula [II] and a repeating unit represented by the following Formula [III]:
wherein in the formula, Z 1 represents an aromatic or alicyclic tetracarboxylic dianhydride residue, and Ar 1 is an aromatic diamine residue having a carboxyl group
wherein in the formula, Z 2 represents an aromatic or alicyclic tetracarboxylic dianhydride residue and Ar 2 represents an aromatic diamine residue having an aromatic ether bond.
5. The electrode according to claim 1 , said binder resin containing a solvent-soluble polyimide having a repeating unit represented by the following-Formula [IV]:
wherein in the formula, Z 3 represents an aromatic or alicyclic tetracarboxylic dianhydride residue and Ar 3 is an aromatic diamine residue having a phenylindan structure.
6. The electrode according to claim 5 , wherein the solvent-soluble polyimide is a block copolymer comprising a repeating unit represented by the following Formula [III] and a repeating unit represented by the following Formula [IV]:
wherein in the formula, Z 2 represents an aromatic or alicyclic tetracarboxylic dianhydride residue and Ar 2 represents an aromatic diamine residue having an aromatic ether bond:
wherein in the formula, Z 3 represents an aromatic or alicyclic tetracarboxylic dianhydride residue and Ar 3 is an aromatic diamine residue having a phenylindan structure.
7. The electrode according to claim 6 , wherein the aromatic diamine component having a phenylindan structure constituting the solvent-soluble polyimide is from 25% by mole to 90% by mole of the total aromatic diamine component.
8. The electrode according to claim 1 , wherein Z is the aromatic tetracarboxylic dianhydride residue, and the aromatic tetracarboxylic dianhydride for introducing the aromatic tetracarboxylic dianhydride residue is 3,4,3′,4′-biphenyltetracarboxylic acid dianhydride and 4,4′-oxydiphthalic acid dianhydride.
9. The electrode according to claim 1 , wherein the sum of the aromatic diamine component having a carboxyl group and the aromatic diamine component having an aromatic ether bond is 100% by mole among the diamine components.