Lithium battery internal materials include negative electrode material, electrolyte, separator, positive electrode material, etc. The quality of the positive and negative materials directly determine the performance and price of the lithium battery. Therefore, the research of low-cost and high quality positive and negative materials has always been the focus of the development of the lithium battery industry. The negative electrode material is generally made of carbon material, and it is now well developed. The common positive electrode material are LCO(LiCoO2), LFP(LiFePO4) and NCM(LiNixCoyMn(1-x-y)O2).
The development of positive electrode materials has become an important factor to improve the performance and reduce the price of lithium batteries. In the current commercial production of lithium batteries, the cost of the positive electrode material accounts for about 40% of the total battery cost, so the price of the positive electrode material directly determines the price of the lithium battery, especially for power lithium batteries. For example, a small lithium battery for a mobile phone requires about 5g of positive electrode material, and a lithium battery bus may requires 500kg of positive electrode material.
To measure the quality of the positive electrode material of lithium battery, it can be evaluated from the following aspects: (1) The positive electrode material should have a high oxidation-reduction potential, so that the battery has a higher output voltage; (2) A large number of reversible insertions and deinsertions of lithium ions occur in the positive material, which makes the battery have high capacity ; (3) in the process of lithium ion insertion/deinsertion, the structure of the positive electrode material should be changed as little as possible, Ensure good cycle performance of the battery; (4) in the process of insertion/deinsertion of lithium ions, the oxidation-reduction potential of the positive electrode should be changed as little as possible so that the voltage of the battery does not change significantly and the battery charging and discharging is stable; (5) The positive electrode material should have a high electrical conductivity, which can make the battery charge and discharge at a large current; (6) the positive electrode does not react with the electrolyte; (7) in order to charge and discharge the battery quickly, the lithium ion should have a large diffusion in the electrode material; (8) the price is cheap and environment friendly.