Negative electrode material and preparation method thereof, electrochemical device and electronic device

Abstract

The invention provides a negative electrode material and a preparation method thereof, an electrochemical device and an electronic device.The negative electrode material comprises a silicon-based material, and metal elements are arranged on the surfaces of silicon-based material particles; the metal element comprises at least one of Ge, Al, Zn, Sn, Sb, Bi, Fe, Mg, Ti, Cr, Mn, Co, Ni, Cu or Pb. The negative electrode material provided by the invention can effectively improve the conductivity of the material, improve the cycle performance of the negative electrode material and reduce the expansion rate of the battery.

Description

technical field [0001] The present application relates to the technical field of negative electrode materials, in particular, to negative electrode materials and preparation methods thereof, electrochemical devices and electronic devices. Background technique [0002] At present, silicon-based anode materials have a gram capacity as high as 1500mAh / g to 4200mAh / g, and are considered to be the most promising next-generation lithium-ion anode materials. But the electrical conductivity of silicon (resistivity>10 8 Ω.cm) is low, in order to improve the electrical conductivity of the silicon material, the silicon material is usually compounded with a carbon material to increase its electrical conductivity. However, when silicon-carbon composite is used, it is easy to increase the oxygen content of the material, and the increase of oxygen content in the negative electrode material will directly lead to the decrease of the first effect of the negative electrode material. In ad...

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Problems solved by technology

But the electrical conductivity of silicon (resistivity>10 8 Ω.cm) is low. In order to improve the conductivity of silicon materials, silicon materials are usually combined with carbon materials to increase their conductivity.

However, when silicon-carbon composites are used, it is easy to increase the oxygen content of the material, and the increase in the oxygen content in the negative electrode material will directly lead to the reduction of the first effect of the negative electrode material.

In addition, the silicon material has a volume expansion of about 300% during charge and discharge and generates an unstable solid electrolyte interfacial film (SEI). The silicon negative electrode material will pulverize and fall from the current collector during charge and discharge, making the active material The loss of electrical contact with the current collector leads to poor electrochemical performance, capacity attenuation, and decreased cycle stability, which hinders its further application to a certain extent.

The existing silicon-based anode materials have low electrical conductivity, which limits their charge / discharge efficiency, low first effect and poor cycle performance

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