Negative material is an important part of lithium-ion battery, it directly affects the battery energy density, cycle life and safety performance and other key indicators. With the new energy vehicles in the practical application of the mileage requirements continue to improve, power battery-related materials to provide a higher energy density in the direction of development. Traditional lithium-ion battery graphite anode has been unable to meet the existing needs, high-energy density anode material to become a new hot pursuit of business. Silicon-based materials due to the rich reserves and ultra-high theoretical than the capacity is gradually becoming the battery companies and lithium materials to improve the negative first choice, is the most promising one of the next generation of lithium-ion battery anode material.
Lithium outbreak of silicon carbon anode material spring came
There is no obvious advantage
Silicon material in the application of lithium-ion battery, mainly related to two aspects, one in the anode material by adding nano-silicon, the formation of silicon carbon anode, first in the electrolyte by adding organosilicon compounds to improve the nature of the electrolyte.
In the anode material, the silicon material is mainly used in the form of nano-silicon. Nano-silicon refers to the diameter of less than 5 nm crystalline silicon particles, is an important non-metallic amorphous materials, often by the sol-gel method and other methods. Nano-silica powder with high purity, small particle size, uniform distribution, specific surface area, high surface activity, loose density and low characteristics, and non-toxic, tasteless. Nano-silicon and graphite materials composed of silicon-carbon composite materials, as a lithium-ion battery anode material, can greatly improve the capacity of lithium-ion battery.
Lithium batteries currently on the market for the use of graphite anode material, from the graphite grams of capacity and compaction density, the anode material energy density is difficult to be improved. In addition, the graphite sheet is also prone to peeling, recycling performance is not ideal and so on.
Compared with the graphite anode material, the energy density of the silicon-based anode material has obvious advantages. The theoretical energy density of graphite is 372 mAh / g, while the theoretical negative energy density of the silicon anode is over 10 times, up to 4200 mAh / g. Silicon carbon composite material can greatly enhance the capacity of single cell, effectively alleviate the industry's worries about the mileage of electric vehicles.
Of course, silicon-based materials also have obvious shortcomings, mainly in the following two aspects: 1, in the charge and discharge process will cause the silicon volume expansion of 100% to 300%, huge volume effect and lower conductivity will limit the silicon anode The commercialization of technology. 2, silicon is a semiconductor, the conductivity is much worse than graphite, resulting in lithium ion disassembly process irreversible degree, further reducing its first Coulomb efficiency.