▎ 摘　　要

NOVELTY - A reduced graphene-type material comprises a film comprising 0.8-2.0 atomic% lithium element, 0.5-2.0 atomic% phosphorus element, 0.05-1.0 atomic% fluorine element, and 7.0-12.0 atomic% oxygen element. USE - Reduced graphene-type material used for lithium-ion secondary battery (claimed). Uses include but are not limited to mobile telephone, notebook personal computer, tablet-type terminal, portable game machine, cart for an electric vehicle, hybrid car, electric motorcycle, electric-power-assisted bicycle, conveyance, robot, drone, etc. ADVANTAGE - The reduced graphene-type material has excellent capacity, and provides lithium-ion secondary battery having improved initial stage charging/discharging efficiency. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following: (1) lithium-ion secondary battery, which comprises a positive electrode including a positive electrode active material which can occlude-discharge lithium ion, negative electrode including a negative electrode active material which can occlude-discharge lithium ion, and a nonaqueous electrolyte, where the negative electrode active material includes the reduced graphene-type material; and (2) manufacture of reduced graphene-type material, which involves heat-treating graphene oxide together with lithium difluorophosphate.