What is the core technology of power lithium ion battery

Lithium ion battery is the representative of modern high-performance battery, which is composed of four important parts: cathode material, negative material, separator and electrolyte.

Separator is an important part of lithium-ion battery pack, which is an important component to support the electrochemical process of lithium-ion battery. It is located between the positive and negative electrodes of the battery, which ensures the passage of lithium ion and hinders the transmission of electrons. The performance of the separator determines the interface structure and internal resistance of the battery, which directly affects the capacity, cycle and safety performance of the battery.

The electrolyte of lithium-ion battery pack is usually mixed with ring carbonate with high dielectric constant and linear carbonate with low dielectric constant. Generally speaking, the electrolyte of lithium-ion battery should meet the requirements of high ionic conductivity (10-3 ~ 10-2s / cm), low electronic conductivity, wide electrochemical window (0 ~ 5V), good thermal stability (- 40 ~ 60 ℃). The technology of lithium hexafluorophosphate and other new lithium salts, solvent purification, electrolyte preparation and functional additives has been continuously improved. The current development direction is to further improve its working voltage and improve the high and low temperature performance of batteries. Safe ionic liquid electrolyte and solid electrolyte are under development.

Graphite, hard / soft carbon and alloy materials can be used as anode materials for power lithium-ion batteries. Graphite is widely used as anode material, and its reversible capacity has reached 360mah / g. Amorphous hard carbon or soft carbon can meet the demand of battery in high rate and low temperature application, and it begins to be applied, but it is important to mix it with graphite. Lithium titanate anode material has the best rate performance and cycle performance, which is suitable for high current fast charging battery. However, the specific energy of the battery is low and the cost is high.

Lithium iron phosphate battery pack has high safety and long service life. At present, the development speed of nano power materials and high-density lithium ferromanganese phosphate materials is fast. The performance of high-energy and high-power materials tends to be stable, and the cost is further reduced, which gradually meets the domestic market demand and the promotion of new energy vehicles in China at the present stage High specific capacity lithium rich manganese based cathode materials are still under development.

For a long time in the future, lithium-ion battery pack is still the most suitable battery for electric vehicles. The development of lithium manganese oxide cathode material, ternary system cathode material, lithium iron phosphate cathode material, composite carbon negative electrode material, ceramic coating diaphragm, electrolyte salt and functional electrolyte technology support the progress of battery technology and industrial development. Battery system technology is progressing in application, and its safety and reliability will be further improved in the next few years.