lithium ion battery cells 18650 anode material—silicon anode material research

　　lithium ion battery cells 18650 anode material-silicon anode material research. As one of its key components, the negative electrode directly determines the performance of lithium-ion batteries. Currently, commercial lithium battery negative electrode materials are mainly graphite-like carbon negative electrode materials, and their theoretical specific capacity is only 372mAh/g (LiC6), which seriously limits the use of lithium batteries. Further developments in ion batteries. Silicon-based materials are the research system with the highest theoretical specific capacity among the negative electrode materials under development.

　　1. Research progress on lithium ion battery cells 18650 anode materials—silicon-based anode materials

　　Silicon is the currently known lithium ion battery cells 18650 anode material with the highest specific capacity (4200mAh/g). However, due to its huge volume effect (>300%), the silicon electrode material will pulverize and peel off from the current collector during the charge and discharge process. , causing the electrical contact between the active material and the active material, and the active material and the current collector to be lost, and at the same time, new solid-phase electrolyte layer SEI is continuously formed, ultimately leading to the deterioration of the electrochemical performance.

　　Silicon-based anode materials are regarded as one of the alternatives to existing commercial carbon anode materials. However, they cannot be commercialized due to the large volume effect during the charge and discharge process. For this reason, researchers have conducted a large number of modification studies. . Silicon-based anode material researchers generally believe that when the size of silicon is small to a certain extent, the impact of the silicon volume effect can be relatively reduced, and small particles of silicon coupled with corresponding dispersion technology can easily reserve enough space for silicon particles. Expansion space, therefore nanometerization of silicon is considered to be an important way to solve the commercialization of silicon-based anode materials.

　　In order to achieve commercial application of silicon-based materials, composite modification must be carried out through a variety of means, and new engineering technologies need to be developed to achieve large-scale controllability.

　　2. Nano silicon carbon anode material for lithium ion battery

　　As an anode material for lithium-ion batteries, nanometer silicon carbon has high lithium storage capacity (theoretical capacity at room temperature is as high as 3580mAh/g, far exceeding graphite (372mAh/g)), good electron channels, small strain, and promotes stable growth of SEI films. environment of. Based on the above advantages, this material is expected to replace graphite as the next generation high-energy-density lithium ion battery cells 18650 anode material.

　　It is undeniable that there are many problems on it: the volume expansion and contraction of silicon particles during deintercalation causes particle pulverization, shedding and electrochemical performance failure; the solid electrolyte layer (SEI) on the surface of silicon particles The continued growth will cause irreversible consumption of the electrolyte and the source of energy from the positive electrode.

　　3. Silicon oxide anode material for lithium-ion batteries

　　The industrial raw material silicon oxide (SiOx, 0

　　SiOx lithium battery anode material is a very promising lithium ion battery cells 18650 anode material. It provides high-capacity ultra-fine nano-Si clusters evenly dispersed in the SiOx matrix, and during the first lithium insertion process, Li4SiO4 and Li2O are generated in situ. The inert phase coats the periphery of the nano-Si clusters, which isolates the contact between Si and the electrolyte. It plays the dual role of buffering the volume effect and protecting the electrochemically active nano-Si clusters. Therefore, it has the characteristics of high capacity and long cycle. performance.

　　4. Silicon carbon anode material

　　As a new lithium ion battery cells 18650 anode material, silicon-carbon anode is more efficient than the current graphite anode in increasing battery energy density. However, due to the high barriers to its application, it is still in the early stages of industrialization in China. In foreign countries, Panasonic has achieved mass production of 18650 batteries containing silicon-carbon anode materials, and Tesla has applied silicon-carbon anodes to vehicle power batteries. The application prospects of silicon-carbon anode materials are getting brighter. In the future, silicon-carbon anode materials It is likely to become the leader among negative electrode materials.

　　Summary: Lithium battery anode materials are currently the most critical link in the lithium ion battery cells 18650 industry. Anode materials account for 25% to 28% of the total cost of lithium batteries. , driven by large-scale investment in the lithium ion battery cells 18650 industry, the demand for anode materials for lithium-ion batteries continues to rise. Silicon anodes have higher mass energy density and volume energy density than graphite anodes, so silicon anode materials will have very broad application prospects.

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