Preparation method for modified graphite anode material

Abstract

The invention discloses a preparation method for a modified graphite anode material. The preparation method comprises the following steps: (1) preparing a slurry precursor; (2) drying the precursor; (3) performing heat treatment. The prepared graphite anode material has higher specific capacity; the material is modified, so that the electrical conductivity of the material is effectively improved, and the cyclic stability of the material is improved; therefore, when the anode material is used for a lithium ion battery, higher energy density and good cyclic stability are achieved.

Description

technical field [0001] The invention relates to a preparation method of a modified graphite negative electrode material, in particular to a preparation method of a graphite negative electrode material doped with metallic nickel and metallic silicon and treated by coating. Background technique [0002] Lithium-ion batteries have the advantages of small size, high storage capacity and high discharge capacity under long-term use, so they are widely used in communication, electronic and other equipment. Based on its safety and cost considerations, "graphite" has become the mainstream raw material for lithium-ion battery anode materials; and various lithium-ion battery anode materials using graphite as raw materials, as well as related preparation methods, have gradually been developed. [0003] At present, the anode materials of commercial lithium-ion batteries use graphite-like carbon materials, which have the advantages of low lithium intercalation / deintercalation potential, s...

AI Technical Summary

Problems solved by technology

However, similar to other high-capacity metals, silicon has very poor cycle performance and cannot perform normal charge-discharge cycles.

When silicon is used as a negative electrode material, the reversible formation and decomposition of Li2Si alloy is accompanied by a huge volume change during the charge-discharge cycle, which will cause mechanical splitting of the alloy (creating cracks and pulverization), resulting in the collapse of the material structure and the electrode material. The peeling of the electrode material will cause the electrode material to lose electrical contact, resulting in a sharp drop in the cycle performance of the electrode, and finally lead to electrode failure, so it is difficult to be practically applied in lithium-ion batteries

Studies have shown that small particle size silicon or its alloys have greatly improved both in terms of capacity and cycle performance. When the particles of alloy materials reach the nanometer level, the volume expansion during charge and discharge will be greatly reduced, and the performance will also be improved. It will be improved, but nanomaterials have a large surface energy and are prone to agglomeration, which will reduce the charge and discharge efficiency and accelerate the decay of capacity, thereby offsetting the advantages of nanoparticles; silicon films prepared by various deposition methods can To a certain extent, the cycle life of the material can be extended, but its high initial irreversible capacity cannot be eliminated, which restricts the practical application of this material.

Images