| 摘要 |
PROBLEM TO BE SOLVED: To prevent the gelling of a vinylidene fluoride polymer without adding an organic acid by using a copolymer containing a specified value or more of vinylidene fluoride and a,specified value or more of chlorotrifluoroethylene as the vinylidene fluoride polymer in a depolarizing mix formed of an electrode active material of composite metal oxide, a conductive assistant, the vinylidene fluoride polymer and an organic solvent. SOLUTION: A vinylidene fluoride polymer contains a copolymer containing 70 mole % or more, preferably, 85-99 mole % or more of vinylidene fluoride and at least 0.5 mole %, preferably, 1-15 mole % of chlorotrifluoroethylene, and a modified matter thereof. In order to provide a desired gelling preventing effect, 0.5 mole % or more of chlorotrifluoroethylene is necessary, and when the vinylidene fluoride content is less than 70 mole %, the swelling property by electrolyte of the vinylidene fluoride copolymer is enhanced to deteriorate the performance of a battery. Thus, the gelling of the vinylidene fluoride polymer is prevented in its use as a positive electrode binder. |
