▎ 摘　　要

NOVELTY - Preparing graphene from biological calcium carbonate source, comprises (a) removing an organic matter in biological calcium carbonate by heating to 400-550 degrees C to obtain pure biological calcium carbonate, (b) adding the pure biological calcium carbonate and a metal reducing agent in a mass ratio of 1:0.01-2.4 into a high-temperature furnace, reacting at 600-750 degrees C for 0.5-8 hours under an inert atmosphere, and then cooling to obtain a black product, and (c) treating the black product with 0.5-6 M aqueous acid solution for 0.5-12 hours, then filtering, and drying to obtain final product. USE - The graphene is useful as electrode material in lithium ion secondary batteries and supercapacitors (claimed). ADVANTAGE - The method: has low cost; and utilizes easily available raw materials, and simple devices. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for: (1) use of graphene as anode material (optionally combined with other anode material) in lithium ion secondary battery, where mixing amount of the graphene material is not less than 5% of the total mass of the active electrode material; and (2) use of graphene as electrode material (optionally combined with other electrode material) in supercapacitor, where mixing amount of the graphene material is not less than 5% of the total mass of the active electrode material.