CELLULOSE FIBER AGGREGATE, SEPARATOR FOR NONAQUEOUS ELECTROLYTE SECONDARY BATTERY, NONAQUEOUS ELECTROLYTE SECONDARY BATTERY AND PRODUCTION METHOD OF CELLULOSE FIBER AGGREGATE

摘要

PROBLEM TO BE SOLVED: To provide a cellulose fiber aggregate which has excellent mechanical strength, keeps the excellent mechanical strength even in a state of being immersed in an electrolyte when used as a separator for secondary batteries and prevents short circuits between the positive and negative electrodes.SOLUTION: A cellulose fiber aggregate includes a cellulose fiber aggregate material containing cellulose fiber and a skin layer which covers at least a part of the surface of the cellulose fiber and contains a polymer of a polymerizable compound having two or more radical polymerizable functional groups in one molecule.