Conductive polymer-doped carbon silicon lithium battery negative electrode material and preparation method thereof

Abstract

The invention discloses a conductive polymer-doped carbon silicon lithium battery negative electrode material and a preparation method thereof. A silicon ball with good monodispersity is used as a silicon source, through conductive polymer doping, and mechanical mixing with graphene nanosheets, conductive carbon black and carbon fiber is carried out to obtain a composite lithium battery negative electrode material. The nanometer-scale silicon has a small absolute change in volume during the process of deinsertion and insertion of lithium, the structural damage of the material can be slowed down, the conductive polymer can provide a fast migration channel for electrons and can buffer the volume effect of the active material silicon during charge and discharge processes, and the conductivityof the material is improved. The lithium battery negative electrode material prepared in the method can perfectly solve the defects of the traditional material, the comprehensive performance of the material is improved to a great extent, the conductivity and the mechanical strength are significantly improved, and the market potential is large, and the social benefits are good.

Description

technical field [0001] The invention belongs to the field of electrode materials, in particular to a carbon-silicon lithium battery negative electrode material, in particular to a carbon-silicon lithium battery negative electrode material doped with conductive polymers and a preparation method thereof. Background technique [0002] In recent years, with the rapid development of my country's national economy and the rise of various portable electronic devices, the application of lithium-ion batteries has become more and more extensive. The performance requirements of the battery are also further improved. Lithium-ion batteries are mainly composed of four parts: positive electrode, negative electrode, separator and electrolyte, and lithium-ion negative electrode material is one of the key factors determining the performance of lithium-ion batteries. As the four main materials of lithium batteries, negative electrode materials account for 20% to 25% of the total cost. Compared...

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Problems solved by technology

[0006] 1. The current commercial lithium-ion battery anode material is mainly graphite, but because of its low theoretical specific capacity (372mAh / g), and the lithium intercalation potential is close to that of metal lithium, the phenomenon of "lithium separation" is prone to occur during fast or low-temperature charging and discharging Cause safety hazards, thus unable to meet the development needs of high-energy power lithium-ion batteries;

[0007] 2. Silicon-based materials, the current research hotspot, have the highest theoretical specific capacity (4200mAh / g) among existing materials, but the volume effect of silicon in the process of intercalation and delithiation is large (up to 300%), which leads to the crushing of active materials and the destruction of electrode structures. Destruction, and the huge volume effect makes it difficult to form a stable surface solid electrolyte (SEI) film on the surface of the active material, causing the capacity to decay rapidly;

[0008] 3. For the low specific capacity of graphite materials and the huge volume effect of silicon materials, Si / C composite materials are the most researched at present. Although Si / C composite materials combine the advantages of the two materials to a certain extent, there are still the following defects. : (1) It is difficult to uniformly disperse silicon nanoparticles in the carbon body, which will cause the nano-silicon particles to easily agglomerate or be exposed to the electrolyte during the lithium intercalation process, which will accelerate the decay of its capacity; (2) During the charging and discharging process, due to the huge volume expansion of silicon particles, the carbon coating is broken, which greatly weakens its ability to buffer the volume effect of silicon.

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