SEPARATOR, ELECTRODE GROUP, SECONDARY BATTERY, BATTERY PACK, VEHICLE, AND STATIONARY POWER SUPPLY

A separator includes an inorganic particle layer including an inorganic particle, a polymeric binder and a fiber substance. A mass ratio of the fiber substance with respect to a total mass of the inorganic particle, the polymeric binder and the fiber substance is 0.1 mass % or more and 40 mass % or less.