The performance of the separator determines the battery's interface structure, internal resistance, and other characteristics, directly affecting the battery's capacity, cycle life, and safety performance. High-performance separators are of great importance in improving the overall performance of batteries.
Electrolytes for lithium-ion batteries are generally a mixture of high-dielectric-constant cyclic carbonates and low-dielectric-constant linear carbonates. Generally, lithium-ion battery electrolytes should meet requirements such as high ionic conductivity (10⁻³~10⁻² S/cm), low electronic conductivity, wide electrochemical window (0~5V), and good thermal stability (-40~60℃). With continuous advancements in lithium hexafluorophosphate and other novel lithium salts, solvent purification, electrolyte formulation, and functional additives, current development trends focus on further improving operating voltage and enhancing high- and low-temperature performance. Safe ionic liquid electrolytes and solid electrolytes are under development.
Anode materials suitable for power lithium-ion battery packs include graphite, hard/soft carbon, and alloy materials. Graphite is currently the most widely used anode material, with a reversible capacity reaching 360 mAh/g. Amorphous hard or soft carbon can meet the requirements of batteries in higher rate and lower temperature applications and is beginning to be used, but importantly, it is used in combination with graphite. Lithium titanate anode materials have the best rate performance and cycle performance, making them suitable for high-current fast-charging batteries, but the resulting batteries have lower specific energy and higher cost.
Lithium iron phosphate battery packs are safe and have a long lifespan. Currently, the development of nanoscale power materials and high-density lithium manganese iron phosphate materials is progressing rapidly. The performance of high-energy and high-power materials is becoming more stable, and the cost is further decreasing, gradually meeting the needs of the domestic market and the current promotion of new energy vehicles in my country. High-voltage spinel nickel manganese oxide and high-voltage, high-specific-capacity lithium-rich manganese-based cathode materials are still under research and development.
