No. 371: New binder for the cathode of lithium-ion secondary batteries (December 5, 2011)

JSR will put its new binder for the cathode of lithium-ion secondary batteries on the market in December. The new binder can halve the required amount as compared with the existing products. Smaller amount used reduces the resistance of a cathode and improves the high-speed charge-discharge characteristics of a battery. At the same time, the new binder does not require equipment to collect solvent in the electrode production line because it is granulous latex dispersed in water, thus the production cost can be reduced.

The latex binder has not been used for cathodes because the oxidation reaction of a cathode deteriorates the latex binder. The company solved the problem by creating a composite using fluorinated polymer excellent in oxidation resistance and acrylate polymer with adhesion force on a molecule level. The polyvinylidene fluoride (PVDF) is current used for cathodes, but it requires equipment to collect solvent because it is dispersed in solvent. The company plans to market the new binder with an emphasis on the fact that it is dispersed not in solvent but in water and that it can reduce the initial investment in the battery production line. Evaluations by customers confirmed that the new binder exhibits the same adhesion force with less than half the amount required by PVDF.