Composite modified graphite negative electrode material and preparation method thereof

Abstract

The invention discloses a composite modified graphite negative electrode material and a preparation method thereof. The preparation method comprises the following steps: 1) mixing graphite, an oxidantand an intercalator according to a certain mass ratio to obtain a mixed solution; 2) carrying out stirring reaction on the mixed solution under a constant temperature condition to obtain an intercalation product; and 3) repeatedly washing the intercalation product with deionized water until the pH value of the filtrate is 57, drying the washed intercalation product, heating to a target temperature in an inert atmosphere, and keeping the temperature for a specific time to obtain the target object. The composite modified graphite negative electrode material prepared by the method disclosed by the invention is manganese oxide loaded sulfur-free micro-expanded graphite, and has nanopores and properly enlarged graphite lamellar spacing. The method has the advantages of being high in operability, easy to produce, low in equipment requirement and good in repeatability, and the prepared composite modified graphite negative electrode material has high specific capacity, excellent rate capability and long cycling stability and is easier to use in the field of commercial lithium ion batteries.

Description

technical field [0001] The invention belongs to the technical field of graphite materials, and in particular relates to a composite modified graphite negative electrode material for lithium ion batteries and a preparation method thereof. Background technique [0002] Compared with other electrochemical batteries (such as lead-acid batteries, nickel-cadmium batteries, nickel-metal hydride batteries), lithium-ion batteries have higher energy density and power density, long cycle life, high working voltage, good safety performance and environmental friendliness And other characteristics, has been widely used in portable electronic devices, and is being gradually promoted into new energy vehicles, renewable energy storage, energy saving and emission reduction and other fields. Structurally, lithium-ion batteries can be divided into four parts: the positive electrode that provides the lithium source, the negative electrode that can intercalate lithium, the separator that prevents...

AI Technical Summary

Problems solved by technology

The rate performance and cycle performance of the obtained manganese oxide-small-sized micro-diffusion layer natural graphite anode have been significantly improved compared with natural flake graphite, but due to the use of concentrated sulfuric acid as an intercalation agent, some of the obtained anode materials will be Sulfur element remains, and the intermediate product of sulfur during charging and discharging will dissolve into the electrolyte, increasing the viscosity of the electrolyte and reducing the ion conductivity. At the same time, the combination product of sulfur and lithium ions, Li 2 S n It is electronically insulating and insoluble in the electrolyte. It is deposited on the conductive framework to reduce the conductivity of the entire negative electrode, resulting in poor performance of the entire negative electrode. It is currently not suitable for use in the field of lithium-ion batteries

[0005] The commercialized graphite negative electrode has low specific capacity, poor rate performance, and poor cycle performance, and the existing schemes for modifying graphite have complex operations, high costs, high equipment requirements, difficulty in expanding production, and insignificant product performance improvement. There are problems such as defects in the composition, which seriously hinders the development of high-performance lithium-ion batteries

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