Electrode binder composition for lithium ion electrical storage devices
An electrode binder of a lithium ion battery comprising: (a) a polyvinylidene binder dispersed in an organic diluent with (b) a (meth)acrylic polymer dispersant. The binder can be used in the assembly of electrodes of lithium ion batteries.
1. A binder composition comprising a dispersion of:
(a) a polyvinylidene fluoride polymer dispersed in an organic dispersion medium with
(b) a (meth)acrylic polymer dispersant having a glass transition temperature of 100° C. or less, wherein the (meth)acrylic polymer dispersant is prepared from a mixture of monomers comprising a hydroxyalkyl ester of (meth)acrylic acid present in an amount of up to 30% by weight, the % by weight based on total monomer weight.
2. The binder composition of claim 1 in which the (meth)acrylic polymer dispersant has a glass transition temperature of −50 to +70° C.
3. The binder composition of claim 1 in which the (meth)acrylic polymer dispersant has a glass transition temperature less than 0° C.
4. The binder composition of claim 1 in which the mixture of monomers further comprises a monomer that contains reactive groups that are reactive with the hydroxyl groups or are reactive with themselves.
5. The binder composition of claim 4 in which the reactive groups comprise N-alkoxymethyl (meth)acrylamide groups and/or blocked isocyanate groups.
6. The binder composition of claim 1 further comprising a separately added crosslinking agent comprising an aminoplast resin, a blocked polyisocyanate, and/or a polyepoxide.
7. The binder composition of claim 1 , wherein the mixture of monomers further comprises 30 to 96% by weight of an alkyl ester of (meth)acrylic acid containing from 1 to 3 carbon atoms in the alkyl group, the % by weight based on total monomer weight.
8. The binder composition of claim 1 , wherein the mixture of monomers further comprises 2 to 50% by weight of alpha, beta-ethylenically unsaturated carboxylic acid, the % by weight based on total monomer weight.
9. The binder composition of claim 1 in which the polyvinylidene fluoride polymer is present in amounts of 50 to 98 percent by weight; the (meth)acrylic polymer dispersant is present in amounts of 2 to 50 percent by weight, and the separately added crosslinking agent is present in amounts of 1 to 15 percent by weight, the percentages by weight being based on resin solids.
10. The binder composition of claim 1 in which the organic dispersing medium comprises ketones, esters, or ethers, including mixtures thereof.
11. The binder composition of claim 1 which has a resin solids content of 30 to 80 percent by weight, based on the total weight of the binder composition.
12. The binder composition of claim 1 in which the organic dispersion medium is free of N-methyl-2-pyrrolidone.
13. An electrode slurry comprising:
(a) an electrically active material capable of lithium intercalation/deintercalation, and
binder composition of claim 1 .
14. The electrode slurry of claim 13 in which (a) comprises LiCoO 2 , LiNiO 2 , LiFePO 4 , LiCoPO 4 , LiMnO 2 , LiMn 2 O 4 , Li(NiMnCo)O 2 , Li(NiCoAl)O 2 , carbon-coated LiFePO 4 , or mixtures thereof.
15. The electrode slurry of claim 13 , further comprising (c) a conductive agent.
16. The electrode slurry of claim 15 in which (c) comprises graphite, activated carbon, acetylene black, furnace black or graphene.
17. The electrode slurry of claim 13 , wherein the binder composition further comprises a separately added crosslinking agent, and the polyvinylidene fluoride polymer is present in amounts of 50 to 98 percent by weight, the (meth)acrylic polymer is present in amounts of 2 to 50 percent by weight and the separately added crosslinking agent is present in amounts of 1 to 15 percent by weight, the percentages by weight being based on resin solids.
18. The electrode slurry of claim 13 in which the organic dispersion medium comprises ketones, esters, or ethers, including mixtures thereof.
19. An electrode slurry comprising:
(a) a conductive agent, and
(b) the binder composition of claim 1 .
20. An electrode comprising:
(a) an electrical current collector;
(b) a cured film formed on the collector (a) comprising:
(i) a polyvinylidene fluoride polymer,
(ii) a crosslinked (meth)acrylic polymer dispersant prepared from a mixture of monomers comprising a hydroxyalkyl ester of (meth)acrylic acid present in an amount of up to 30% by weight, the % by weight based on total monomer weight, wherein the crosslinked (meth)acrylic polymer dispersant is crosslinked with a separately added crosslinking agent,
(iii) a conductive material, and
(iv) an electrode active material capable of lithium intercalation/deintercalation.
21. An electrical storage device comprising:
(a) the electrode of claim 20 ,
(b) a counter electrode, and
(c) an electrolyte.