Lithium ion secondary battery, positive electrode material of battery, and preparation method of material

Abstract

The invention provides a lithium ion secondary battery, a positive electrode material of the battery, and a preparation method of the material. The positive electrode material of the lithium ion secondary battery comprises graphene and nanometer sulfur particles which are loaded on the surface of the graphene. The graphene oxide or graphene, nanometer sulfur powder, a surface active agent and a reducing agent are adopted as raw materials, and after being mixed, the raw materials perform hydrothermal reaction to obtain the positive electrode material of the lithium ion secondary battery. The electronic conductivity of the positive electrode material is improved by virtue of the excellent conductivity of the graphene, and the dissolution of polysulfide ions can be alleviated through the unique two-dimensional structure of the graphene, so that the gradual attenuation of the electric capacity can be inhibited, and the cycling property of the battery can be improved. The experimental result shows that the primary discharging capacity of the positive electrode active material can reach 1100mAh / g under 0.1C, the capacity can be maintained at 800mAh / g after the battery is cycled for 50 times, the discharging capacity can be maintained at 450mAh / g under 2C, and the rate performance of the battery is excellent.

Description

technical field [0001] The invention relates to the technical field of lithium-ion secondary batteries, in particular to a lithium-ion secondary battery cathode material, a preparation method thereof and a lithium-ion secondary battery. Background technique [0002] The rapid development of the current communication, portable electronic equipment, electric vehicles and space technology and other fields has put forward higher and higher requirements for the performance of the battery. The development of new lithium-ion secondary batteries with high specific energy, low cost and environmental friendliness has great potential. very important meaning. [0003] In the lithium-ion secondary battery system, the performance of the cathode material has always been the bottleneck restricting the development of the battery. Traditional transition metal oxide-based cathode materials such as LiCoO 2 , LiNiO 2 , LiMn 2 o 4 Due to the limitation of its theoretical lithium storage capa...

AI Technical Summary

Problems solved by technology

However, lithium-sulfur batteries have the following three problems: (1) elemental sulfur does not conduct electricity at room temperature, so the utilization rate of active materials in lithium-sulfur batteries is very low and the electrochemical performance is poor; (2) polysulfide produced during charging and discharging of lithium-sulfur batteries Lithium is easily soluble in organic electrolyte, so that the active material of the electrode gradually decreases, resulting in the gradual decline of battery capacity and poor cycle performance; (3) During the cycle, the volume deformation of the sulfur electrode in the lithium-sulfur battery is as high as 22%, which may Cause microcracks inside the sulfur electrode, the existence of such microcracks destroys the integrity of the electrode, and ultimately aggravates the capacity fading of the lithium-sulfur battery

However, the cycle performance of the lithium-sulfur battery prepared by the positive electrode material obtained from this mesoporous carbon or porous carbon material is poor.

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