The development trend of lithium ion battery materials

Source: 2020 - 04 - 06 treasure hits: 1. The working principle of lithium-ion batteries, lithium ion battery is mobile lithium ion between the positive and negative. In the process of charging and discharging lithium ion battery, mainly depends on lithium ion movement. In the process of charging, lithium ion from the anode, through the electrolyte embedded in the cathode. Principle of discharge process in accordance with the charging process. Lithium is the lightest element in the metal, atomic weight is 6. 94, density of 0. 534 g/cm3, discharge capacity is 3860 mah/g. Lithium ion batteries is mainly composed of the positive, negative and internal composition of the electrolyte. The diaphragm is a special kind of polymer membranes, with pores, is advantageous for the lithium ion free through; Cathode is generally adopt active substances, commonly used are carbon graphite or similar structures of materials; Organic electrolyte is usually dissolved in solvent containing six fluorine lithium phosphate. Battery shell are usually made of steel or aluminum shell, aluminum shell plastic film. 2. The working principle of lithium-ion batteries at present, lithium ion battery has been widely used in the market. The battery has a large energy density, high average output voltage, and the advantages of good cycle performance, can satisfy the requirement of fast charging and discharging. Lithium ion battery efficiency can reach 100%, long service life. Different from some conventional batteries, it does not contain toxic substances, reduce the pollution to the environment. Lithium ion battery cathode are usually made of carbon materials. The anode is usually lithium compounds, lithium is the only active material in lithium-ion batteries. Lithium ion battery in the process of charging, lithium ion anode, then move to the cathode electrolyte. Of pore in carbon materials to promote the movement of lithium ions. Embedded in the pore of carbon material of lithium ion, the battery charging capacity. Similarly, in the process of discharge, the more precipitation in lithium ion from the cathode, the higher the discharge capacity of the battery. 4. The development of lithium ion battery materials 4. 1 early lithium ion battery anode materials commonly used metal lithium, although there are certain advantages, metallic lithium but materials in the process of charging and discharging is easy to cause short circuit or explosion, safety performance is low. With the development of science and technology, the present study focuses on four kinds of material: carbon material, metal oxide, metal nitride and nano silica. The use of carbon materials to promote the movement of lithium ions. Natural graphite materials, large capacity, embedding position, more facilitate lithium ions move, but is sensitive to the electrolyte. Artificial carbon materials have certain impurities. Due to the irreversible of hard carbon materials is larger, when use often add some other elements, such as potassium and boron, thus improve their capacity. Metal oxide as a kind of new anode materials, has the good cycle stability and high stability. Metal nitride as the cathode, good chemical stability, the reversible reserves and high charge and discharge capacity. 4. 2 is currently the most used LiCoO2 cathode materials. The material has good stability, simple manufacturing process. However, there are some problems. In actual use, in order to improve the safety of materials, commonly used to replace the cobalt nickel or manganese. LiNiO2 materials for layered structure, general replace Ni with metallic elements such as Al, Ga, in order to improve its stability. 4. 3 electrolytes in lithium ion battery electrolyte materials play an important role. For the electrolyte, it has good chemical stability, not easy to decompose at high temperature, high electrical conductivity. On the market at present most is using a liquid electrolyte, the solvent for anhydrous organic matter. Lithium ion batteries commonly used lithium/liquid electrolyte mixed carbonate solvent composition, but the liquid electrolyte has serious shortcomings, easy to leak; In contrast, the use of solid electrolyte can avoid the leakage of liquid electrolyte, its safety performance is higher, have better flexibility and stability, its defect is ionic conductivity is low.