High-power-capacity lithium-ion-battery anode material and preparation method thereof

Abstract

The invention belongs to the technical field of lithium ion batteries, and particularly relates to a high-power-capacity lithium-ion-battery anode material. The high-power-capacity lithium-ion-battery anode material comprises a solid electrolyte layer and alloy particles. The particles disperse in the solid electrolyte layer, and the diameters of the particles range from 5 nanometers to 300 nanometers. Compared with the prior art, the high-power-capacity lithium-ion-battery anode material has the advantages that the solid electrolyte layer is adopted to protect the alloy particles with the diameters of 5-300 nanometers, so that powder fall-off of the alloy particles caused by large volume change is avoided, and volume expansion of the material can be controlled to relieve the deformation of anode strips; the solid electrolytes can also play a role in conveying lithium ions, and can isolate the reaction of the alloy particles and electrolytic solutions to avoid consumption of the electrolytic solutions and to protect stability of SEI (solid electrolyte interface) films on the surfaces of the anode strips, so that service life of batteries can be prolonged. In addition, the invention further discloses a preparation method of the anode material.

Description

technical field [0001] The invention belongs to the technical field of lithium ion batteries, in particular to a high-capacity lithium ion battery anode material and a preparation method thereof. Background technique [0002] At present, the mainstream anode material of lithium-ion batteries is commercialized graphite, which is close to the theoretical capacity of graphite (372mAh / g). Therefore, there is little room for improving the energy density of batteries only by improving graphite anode materials. [0003] Silicon can form Li due to its alloying reaction with lithium 3.5 Si, therefore, is capable of delivering capacities as high as 3500mAh / g, approximately ten times that of graphite, and thus attracts the interest of numerous researchers. However, in the alloying reaction, accompanied by a volume change of 300%, problems such as poor electrical contact and severe cycle attenuation limit its commercial promotion (Journal of Power Sources, Volumes 163, 9 November 2006,...

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Problems solved by technology

Objectively speaking, the control of the content of these substances can indeed alleviate the volume change of the entire anode sheet to a certain extent, but it can be seen from their local microscopic curves that the expansion of the particles is still relatively large, which leads to SEI on the surface of the anode sheet The membrane (solid electrolyte membrane) is easily damaged in the process of charging and discharging back and forth, resulting in a large consumption of electrolyte, which eventually leads to the occurrence of battery diving

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