The separator paper in a lithium-ion battery serves to separate the positive and negative electrode materials. The quality of the separator paper directly affects the battery's safety performance and capacity.
Traditional polymer separators are made from polyethylene and polypropylene through processes such as melt extrusion, stretching, and heat setting to produce microporous polyolefin lithium-ion battery separator materials. This material possesses high porosity and tear strength, good acid and alkali resistance, and elasticity, and its physical and chemical properties do not significantly change after hundreds of cycles.
Lithium-ion battery separator materials are mainly used for isolation between the positive and negative electrodes of lithium-ion batteries. They also play a crucial role in preventing short circuits and potential explosions during overcharging by providing overheat self-shutdown protection. As a key material in lithium-ion batteries, the main physicochemical properties of lithium-ion battery separator materials include:
Pore size: The membrane has a certain pore size, which can control the transport speed of ions between the positive and negative electrodes.
Pore size distribution: The size and uniformity of the pores in the separator also have a significant impact on battery performance.
Conductivity: The separator should have good conductivity to ensure a balanced distribution of charge inside the battery.
Mechanical strength: The separator should have sufficient mechanical strength to prevent problems such as internal short circuits or pinholes in the battery.
Chemical stability: The separator should have sufficient chemical stability to ensure that the battery does not decompose or dissolve during long-term operation.
Common lithium-ion battery separator materials include polypropylene (PP), polyimide (PI), and polyimide (PBI). Among them, polypropylene is currently the most commonly used lithium-ion battery separator material due to its low price and good chemical stability.
