Hard carbon cathode material and preparation method thereof, and application of hard carbon cathode material

Abstract

The invention discloses a hard carbon cathode material and a preparation method thereof, and application of a hard carbon cathode material. The method comprises the steps of: (1) performing pre-treatment of a carbon-containing raw material to obtain a hard carbon precursor; (2) performing pre-lithiation treatment on the hard carbon precursor so as to obtain a solid pre-lithiation hard carbon precursor coated with a lithium-containing substance on the surface; (3) performing coating treatment of the pre-lithiation hard carbon precursor and asphalt; and (4) performing carbonizing treatment of the coated pre-lithiated hard carbon precursor obtained in the step (3) in an inert atmosphere, performing crushing, screening and removing magnetism to obtain the hard carbon negative electrode material. The hard negative electrode material is low in preparation cost, and the surface of the hard carbon precursor is coated with the lithium-containing substance and the asphalt so that the first coulombic efficiency of a battery prepared from the hard carbon negative electrode material is not less than 90%, the multiplying power is not less than 98%, and the charge-discharge reversible capacity isnot less than 480 mAh / g.

Description

technical field [0001] The invention belongs to the field of negative electrode materials, in particular, the invention relates to a hard carbon negative electrode material and its preparation method and application. Background technique [0002] With the continuous improvement of power battery energy density and other comprehensive performance requirements, the theoretical capacity of natural graphite and artificial graphite anode materials is 372mAh / g, and it can reach 365mAh / g at present, and it is difficult to increase the anode capacity. Natural graphite and artificial graphite anode materials have been difficult to meet the requirements of high energy density batteries, and hard carbon has attracted more and more attention because of its high specific capacity, excellent cycle, rate and low temperature performance. [0003] Hard carbon is an amorphous carbon that is difficult to graphitize at high temperatures (≥2800°C). It is formed by cross-linking and stacking graph...

AI Technical Summary

Problems solved by technology

However, hard carbon has more pores, rough surface, and large specific surface area, resulting in more side reactions and a large initial irreversible capacity loss.

The first irreversible capacity loss consumes a large amount of lithium ions extracted from the electrolyte and positive electrode material, resulting in a lower first Coulombic efficiency, which also makes the battery discharge capacity lower

[0004] The prior art discloses that plant extracts, resins, and pitches are used as precursors to prepare hard carbon negative electrode materials through processes such as cross-linking polymerization, pre-carbonization, carbonization, and crushing, and then chemical vapor deposition is used to surface the prepared hard carbon materials. Coating modification, the first coulombic efficiency of the final hard carbon material is 84.69%, and the first reversible capacity is 323.5mAh / g, but the first capacity effect is still low

Images