Porous membrane for lithium ion secondary battery and lithium ion secondary battery
AssigneeZeon Corporation
InventorYujiro TOYODA
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Abstract
Provided is a technique for capturing transition metal ions, such as cobalt ions, in a secondary battery that elute into an electrolysis solution from a positive electrode active material. A porous membrane for a lithium ion secondary battery contains non-conductive particles and a particulate polymer. The particulate polymer includes an aliphatic conjugated diene monomer unit in a proportion of greater than 85 mass %. The cobalt concentration in a film of 500 μm in thickness and 12 mm in diameter, formed from the particulate polymer, after the film is immersed in a specific cobalt chloride solution for 5 days at 25° C. is at least 300 mass ppm.
Claims7
A porous membrane for a lithium ion secondary battery comprising
- non-conductive particles and a particulate polymer, wherein
- the particulate polymer includes an aliphatic conjugated diene monomer unit in a proportion of greater than 85 mass %, and
- a cobalt concentration in a film of 500 μm in thickness and 12 mm in diameter, formed from the particulate polymer, after the film is immersed in a cobalt chloride (CoCl2) solution for 5 days at 25° C. is at least 300 mass ppm, where the cobalt chloride (CoCl2) solution is defined as a solution having a cobalt concentration of 18 mass ppm in which a mixture of ethyl methyl carbonate and ethylene carbonate with an ethyl methyl carbonate:ethylene carbonate mass ratio of 70:30 is used as a solvent.
Dependencies are inferred from the claim text.