The negative electrode material is one of the key factors determining the performance of lithium-ion batteries. At present, the negative electrode materials used in commercial lithium-ion batteries mainly include: ① Graphite carbon materials, which are divided into natural graphite and artificial graphite; ② Disordered carbon materials, including hard carbon and soft carbon; ③ lithium titanate materials; ④ silicon-based materials, mainly divided into carbon-coated silicon oxide composites, nano-silicon-carbon composites, and amorphous silicon alloys.
With the rapid development of the economy and the rapid advancement of science and technology, the popularity of electronic products has reached the highest level in history. As one of the important application fields, the development of electric vehicles has led to the improvement of battery performance, but also put forward higher requirements for batteries, including the improvement of energy density and the extension of cycle life. At present, the research on anode materials focuses on new carbon materials, silicon-based materials, tin-based materials and their oxide anode materials.
New carbon materials are related to traditional carbon materials. At present, graphite, a traditional carbon material, is widely used commercially as a negative electrode material for lithium-ion batteries, but its theoretical capacity is low, and it is increasingly unable to meet the development needs of lithium-ion batteries. Novel carbon materials, such as carbon nanotubes and graphene, have great potential in lithium-ion battery applications due to their special one- and two-dimensional flexible structures, excellent thermal conductivity and electrical conductivity.
Compared with other lithium-ion battery anode materials, silicon-based anode materials have very high specific capacity. However, the high expansion rate of silicon during charging and discharging limits its application in negative electrode materials. The negative electrode material prepared by compounding silicon and other materials can overcome this defect to a certain extent.
Metal tin and lithium can undergo alloying reaction to form various intermetallic compounds LixSn (x=0.4, 1.0, 2.33, 2.5, 2.6, 3.5, 4.4), which is a promising anode material for lithium-ion batteries.
