This technology controls the pore size of thermally stable polyimide (PI) separators by coating their large pores with melamine phosphonate (MP). It enhances thermal stability by utilizing endothermic reactions at high temperatures and improves electrolyte absorption.
Conventional polyolefin (PE/PP) separators have low thermal stability, posing a risk of thermal runaway. While polyimide (PI) separators have been proposed as an alternative, they suffer from excessively large pores, which raise concerns about electrode short circuits and low electrolyte absorption.
This technology involves applying a coating composition containing melamine phosphonate and a polymer binder onto a porous PI support to fill and reduce its pores. The coating layer reinforces the mechanical strength of the separator, mitigates internal cell temperature rise through an endothermic reaction at approximately 300°C, and improves electrolyte wettability. Applicable to NCM811-based high-energy lithium-ion batteries and electric vehicle battery packs with strict thermal safety standards, it achieves both short-circuit prevention and thermal runaway delay with a single flame-retardant organic coating.
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