▎ 摘　　要

NOVELTY - A large-scale two-dimensional lithium titanate nanosheet comprises graphene and lithium titanate nanosheet, which is located on graphene surface, and is formed by assembling lithium titanate nanoparticles having special multistage pore structure, and removing graphene by heating in air to obtain pure two-dimensional lithium titanate nanosheet. The preparation method of the graphene-based lithium titanate nanosheet involves adding graphene oxide and tetrabutyl titanate to cyclohexane, stirring, centrifuging, adding the obtained solid to 80 mL cyclohexane, reacting under hydrothermal conditions for 6 hours, centrifuging, washing, and drying to obtain a graphene-based amorphous titanium dioxide film, adding the graphene-based amorphous titanium dioxide film to 0.1-0.2 mol/L lithium hydroxide solution, stirring for 12 hours, drying in an oven to remove the solvent, transferring the obtained solid to a tubular furnace, heating under nitrogen protection, and then cooling. USE - The large-scale two-dimensional lithium titanate nanosheet is useful as cathode active material of lithium-ion battery (claimed), which is useful for electric vehicle, portable electronic product and power grid energy storage system. ADVANTAGE - The large-scale two-dimensional lithium titanate nanosheet has excellent electrochemical performance and pseudocapacitive behavior, and enhances lithium-ion battery performance. DETAILED DESCRIPTION - A large-scale two-dimensional lithium titanate nanosheet comprises graphene and lithium titanate nanosheet, which is located on graphene surface, and is formed by assembling lithium titanate nanoparticles having special multistage pore structure, and removing graphene by heating in air to obtain pure two-dimensional lithium titanate nanosheet. The preparation method of the graphene-based lithium titanate nanosheet involves preparing graphene oxide by Hummer method, adding graphene oxide and tetrabutyl titanate in a mass ratio of (1-5):50 to 60 mL cyclohexane, stirring for 2 weeks, centrifuging, adding the obtained solid to 80 mL cyclohexane, reacting under hydrothermal conditions for 6 hours, centrifuging, washing, and drying to obtain a graphene-based amorphous titanium dioxide film, adding the graphene-based amorphous titanium dioxide film to 0.1-0.2 mol/L lithium hydroxide solution, stirring for 12 hours, drying in an oven to remove the solvent, transferring the obtained solid to a tubular furnace, heating at 700-900degrees Celsius for 5-10 hours under nitrogen protection, and then cooling to room temperature. The preparation method of the graphene-based element-doped lithium titanate nanosheet involves adding graphene-based titanium dioxide film and inorganic salts containing other elements to lithium hydroxide solution, stirring for 12 hours, drying in an oven to remove the solvent, transferring the obtained solid to tubular furnace, heating at 700-900degrees Celsius for 5-10 hours under nitrogen protection, and cooling to room temperature. The preparation method of the pure lithium titanate nanosheet involves transferring the prepared graphene-based lithium titanate nanosheet to a muffle furnace, heating at 500-900degrees Celsius for 2-5 hours in air to remove graphene to obtain product, or adding the graphene-based titanium dioxide film to lithium hydroxide solution, stirring for 12 hours, drying in oven to remove the solvent, transferring the obtained solid to muffle furnace, and heating at 600-900degrees Celsius for 2-5 hours in air. The mass ratio of the graphene-based titanium dioxide and the lithium hydroxide solution used is (1-8):10. The mass ratio of the graphene-based titanium dioxide to the inorganic salts containing other elements is (1-3):1. An INDEPENDENT CLAIM is included for the graphene-based lithium titanate nanosheet, the graphene-based element-doped lithium titanate nanosheet, and the pure lithium titanate nanosheet, which comprise an anode active material, and a lithium sheet used as a cathode to assemble 2032 coin-cell battery, which has obvious pseudocapacitive behavior in the performance test.