The importance of lithium battery electrolyte

The electrolyte is an ionic conductor that conducts between the positive and negative electrodes of the battery. It is composed of lithium electrolyte, high-purity organic solvent, necessary additives and other materials in a certain proportion. It plays a vital role in battery energy density, power density, a wide range of temperature applications, cycle life, and safety functions. The proportion of nickel in the positive electrode is increasing, and the application of the silicon-carbon negative electrode has brought new troubles to the development and processing of the electrolyte. As the energy density of power lithium-ion batteries increases, so does the voltage. The higher the voltage, the stronger the differentiation ability of the electrolyte. Regarding the high nickel ternary system, the electrolyte company specializes in over-leakage current (that is, the current flowing through the insulator) and transition metal ion dissolution tests. The results show that with the correct guess of the nickel content of the positive electrode material of the progressive power battery, the dissolution rate of transition metal ions increases. After the cathode is reduced and separated, the dissolved transition metal ions will destroy the SEI film on the anode surface. In addition, the forward voltage will significantly increase the leakage current. This will affect the storage and circulation functions of the power lithium-ion battery in a high-temperature environment, and the increase in nickel content will also cause the safety function of the power lithium-ion battery to decrease. The problems of high-nickel data and electrolyte matching are more complicated, and the technical threshold is high. If the company is not satisfied with its research capabilities, it will be difficult to match high nickel data with electrolyte products. 1. The search for high specific energy electrolytes is currently the biggest research direction of lithium batteries, especially when people's mobile devices account for an increasing proportion, the life of the battery has become the most critical function of the battery. As shown in the figure, the future development of high-energy-density batteries must be high-voltage anodes and silicon cathodes. -Silicon has a huge gram capacity and people pay attention to it, but because of its expansion effect, it cannot be used. In recent years, the research direction has changed the silicon carbon anode. It has a relatively high gram capacity and small volume changes. , Different films have different additive cycles in the silicon-carbon anode. 2. High-power electrolyte At present, it is difficult for commercial lithium electronic batteries to complete high-rate continuous discharge. The important reason is that the battery's extreme ear temperature is serious, and the internal resistance causes the overall temperature of the battery to be too high, which is prone to thermal runaway. Therefore, while maintaining high conductivity, electrolyte is needed to prevent the battery from heating up too quickly. Regarding power lithium-ion batteries, completing fast charging is also an important direction for electrolyte development. High-power batteries not only put forward high solid phase dispersion, short ion migration path caused by nanometerization, control electrode thickness and compaction and other requirements for electrode data, but also put forward higher requirements for electrolyte: 2. Low solvent complex viscosity; 3. Interface control reduces membrane impedance. 3. Wide-temperature electrolyte When the battery is at a high temperature, the electrolyte is prone to self-differentiation, and the side reaction between the data and the electrolyte is intensified. However, at low temperatures, the electrolyte salt output and negative SEI membrane impedance may increase exponentially. The wide temperature electrolyte provides a wider range of working conditions for the battery. The following figure shows the boiling point comparison and curing comparison of various solvents. 4. The safety of a safe electrolyte battery is mainly reflected in burning or even explosion. First, the battery itself is flammable, so when the battery is overcharged, overdischarged, short-circuited, when the outside is needled or squeezed, when the outside temperature is too high , May cause a safety accident. Therefore, flame retardants are an important direction of safe electrolyte research. Add flame retardant additives to conventional electrolyte to obtain flame retardant effect. Generally, phosphorus flame retardants or halogen flame retardants are used. The flame retardant additives are required to be reasonably priced and do not affect the function of the electrolyte. In addition, the use of room temperature ionic liquids as electrolytes has also entered the research stage, which will completely eliminate the use of flammable organic solvents in batteries. Disclaimer: Some pictures and content of articles published on this site are from the Internet. If there is any infringement, please contact to delete.