Lithium titanate aggregate, lithium ion secondary battery and lithium ion capacitor using the same

摘要

Provided is a lithium titanate particle active material which is capable of increasing cycle characteristics and electrical capacity during high-rate charging and discharging. Lithium titanate primary particles which are characterized by having a step-like structure wherein smooth polygonal plates are laminated. A lithium titanate aggregate wherein the primary particles having the step-like structure and another lithium titanate primary particles having an arbitrary shape aggregate, said lithium titanate aggregate being characterized in that the number of the primary particles having the step-like structure is not less than 10% of the total number of the primary particles. A lithium ion secondary battery and a lithium ion capacitor, each of which uses the primary particles or the aggregate.