Preparation of polymer electrolyte for lithium ion battery

Preparation of polymer electrolytes for lithium ion batteries The preparation methods of polymer electrolytes can be divided into physical methods and chemical methods. The physical method refers to a mixture of polymer solution, lithium electrolyte (or liquid electrolyte) and other additives (such as inorganic powder materials). Through casting or coating, the solvent evaporation temperature, humidity and wind speed can be controlled. After the solvent is volatilized, polymer electrolyte membranes with different morphologies can be prepared. The chemical method refers to the mixture of polymer monomer, initiator and electrolyte lithium salt (or liquid electrolyte), and other additives, which penetrate into the non-woven fabric or lithium ion battery separator (such as Celguard membrane), and use the polymerization method (ultraviolet light or heat). ) Preparation of polymer electrolyte membranes, as described below. 1 Physical method The polymer matrix is u200bu200bdissolved in the appropriate solvent mixture mixed solution in a certain ratio and the electrolyte lithium salt or the polymer matrix is u200bu200bdissolved in the solvent and polymer solution, and then a certain proportion of the electrolyte mixture is added, and then the paint and solvent are completely volatilized. After uncovering the membrane, the polymer electrolyte membrane is obtained. The polymer electrolyte membrane is as thin as possible under the premise of allowing the strength to reduce the ohmic resistance of the lithium ion battery and reduce the polarization. Generally speaking, cast films are suitable for preparing small-sized samples in the laboratory. In the physical method of preparing polymer electrolytes, especially gel polymer electrolytes, the raw materials must be dehydrated first, and the coating process must also be carried out in an anhydrous, oxygen-free glove box or a dry room, which requires a harsh operating environment. During the drying process, organic solvents evaporate, and solvent recovery equipment should be added. Invented in the 1990s, such as Gozdz Bell technology has greatly improved the physical method of the preparation process of polymer electrolyte membrane coatings. This is because the traditional Bellcor technology in the preparation of porous membranes silica agglomerates, is dispersed in the polymer matrix, and phase In the preparation of porous membranes by transfer method, the silica powder is mainly distributed on the inner wall of the pores. It is used for mechanical enhancement to stabilize the pore structure of SiO2 on the pore surface and enhance the composite of the polymer membrane and the electrode. Through rolling, it will not cause porosity. Significantly reduced, it will not lead to the conductivity of the polymer electrolyte membrane. 2 Chemical methods The polymer electrolyte membrane prepared by chemical methods is usually polymerized, whether it is a solid or gel polymer electrolyte preparation, or a surface modified polymer electrolyte membrane, it is manifested in the active ingredients of all materials, and does not involve the use of organic solvents to volatilize Or in the suction filtration process, using light or thermal polymerization, one step can be prepared from polymer electrolytes, especially the liquid electrolyte method prepared by thermal polymerization is compatible with lithium ion batteries, is environmentally friendly and has low production costs, and has obvious advantages. Drop the mixture of monomer, photoinitiator, electrolyte salt (or liquid electrolyte) on non-woven fabric or other substrates (for solid-liquid use), irradiate it with ultraviolet rays, polymerize the monomer after curing, uncover the film, and polymer electrolyte membrane . Regarding the solid polymer electrolyte, the lithium salt is dispersed in the polymer matrix. Regarding the gel polymer electrolyte, a liquid electrolyte is contained in a polymer matrix. In order to prepare polymer electrolytes with good mechanical properties, a crosslinking agent or a monomer containing bifunctional or trifunctional groups is added to the prepolymer solution. The polymer matrix after polymerization has a three-dimensional network structure, which improves the mechanical properties and water retention of the gel polymer electrolyte. The results showed that the polymer electrolyte membrane was prepared by thermal polymerization. The unreacted monomer undergoes a decomposition reaction during the formation stage, and the decomposition product is deposited on the electrode surface, increasing the resistance of the electrolyte/electrode interface. In high-rate discharge and low-temperature discharge, the specific capacity is. As the amount of initiator increases, unreacted monomers decrease, decomposition products decrease, interface resistance decreases, and capacity increases slightly. Disclaimer: Some pictures and content of articles published on this site are from the Internet. If there is any infringement, please contact to delete. Previous article: How to determine the capacity of the lithium-ion battery?