The development trend of lithium-ion batteries

Abstract: Summarizes the development trend of lithium-ion batteries, briefly introduces the current theoretical research status of the charging and discharging mechanism of lithium-ion batteries, and summarizes the current preparation theories and the latest development trends of positive and negative electrodes. The various preparation methods and development prospects of cathode materials and anode materials with lithium battery materials as the core technology are introduced, and the current problems and improvements in this field are emphasized. Keywords: Lithium-ion battery; Electrode material; Electric cycle capacity; Lithium intercalation compound. Introduction The electronic information age has rapidly increased the demand for mobile power supplies. Lithium-ion batteries have important advantages of high voltage and high capacity, and have long cycle life and good safety performance. They have broad application prospects in portable electronic equipment, electric vehicles, aerospace technology, defense industry, etc. It is a research hotspot that has received widespread attention this year. The general analysis of the mechanism of lithium ion batteries believes that the lithium ion battery as a chemical power source refers to a secondary battery composed of two compounds that reversibly intercalate and deintercalate lithium ions, serving as a positive electrode and a negative electrode. When the battery is charged, lithium ions are extracted from the positive electrode and inserted into the negative electrode, and vice versa. Lithium-ion batteries are the product of physics, materials science and chemistry. The physical mechanisms involved in lithium-ion batteries are currently explained by embedded physics in solid-state physics. Intercalation refers to the reversible embedding of movable guest particles (molecules, atoms, ions) into a host lattice of an appropriate size. Click a space in the network. Both the positive electrode material and the negative electrode material of the electron transport lithium ion battery are mixed compounds of ions and electron intercalation compounds. Electrons can only move in positive and negative materials [4] [5] [6]. There are many known intercalation compounds, and the guest particles can be molecules, atoms or ions. When ions are inserted, charge compensation is required from the main structure to maintain electrical neutrality. Charge compensation can be achieved by changing the band structure of the host material, and the conductivity will change before and after embedding. Whether the electrode material of lithium ion battery can stably exist in the air is closely related to this characteristic. If the intercalation compounds satisfy the reversible structural changes and can compensate for the changes in the charge in the structure, they can only be used as electrode materials for lithium-ion batteries. The key materials that control the performance of lithium-ion batteries-the positive and negative active materials in the battery are the key to this technology, which is the consensus of researchers at home and abroad. 1 The performance of the cathode material and the general preparation method The important parameter that characterizes the ion transport performance in the cathode is the chemical diffusion coefficient. Generally, the diffusion coefficient of lithium ions in the positive electrode active material is low. Lithium is inserted into or deintercalated from the positive electrode material together with the crystal phase change. Therefore, the electrode film of a lithium ion battery is required to be very thin, usually several tens of microns. The lithium intercalation compound of the positive electrode material is a temporary storage container for lithium ions in a lithium ion battery. In order to obtain a higher battery voltage, it is preferable to select a lithium intercalation compound with a high potential. The cathode material should meet: 1) within the required charge and discharge potential range, and have electrochemical compatibility with the electrolyte; 2) mild electrode process kinetics; 3) highly reversible; 4) fully lithiated Stability in the air. Research hotspots mainly focus on layered LiMO2 and spinel LiM2O4 compounds and similar electrode materials with two kinds of M (M is Co, Ni, Mn, V and other transition metal ions). As the cathode material of lithium ion batteries, the degree and reversibility of structural changes during the deintercalation and intercalation of Li + ions determine the stable and repeated charging and discharging of the battery. In the preparation of cathode materials, raw material properties and synthesis process conditions will have an impact on the final structure. Various promising cathode materials will attenuate the capacity during use, which is the main problem in the research. Disclaimer: Some pictures and content of articles published on this site are from the Internet, please contact to delete if there is any infringement. Previous: Solid-state lithium battery technology is expected to seize market opportunities