Binder for separator of non-aquaous electrolyte battery comprising 2-cyanoethyl group-containing polymer and separator and battery using the same

Provided is a binder used for a heat-resistant porous layer which is comprised by a separator; a separator which comprises the binder and which is comprised by a non-aqueous electrolyte battery with improved stability; and a non-aqueous electrolyte battery comprising the separator. More specifically, provided is a binder for a separator of a non-aqueous electrolyte battery, the binder comprising at least a 2-cyanoethyl group-containing polymer having storage elasticity of 100 Pa or more in a mixed liquid of specified cyclic carbonate ester, specified chain carbonate ester and lithium phosphate hexafluoride.