钠电池 SEI 膜的质量对循环寿命有什么影响？

How does SEI film quality affect the cycle life of sodium-ion batteries?

SEI 致密性、稳定性、厚度直接决定电芯循环寿命，是核心界面影响因素。高品质 SEI 均匀坚韧，负极反复嵌脱钠产生形变时不会开裂，长效阻隔副反应，钠离子不可逆损耗极低，可稳定完成 3000 次以上循环，容量平缓下降。劣质 SE 疏松脆薄，循环中频繁破损，裸碳持续和电解液反应消耗活性钠；破损处反复新生 SE，膜持续增厚，电芯内阻不断上升，充放电发热加剧。数千次循环后容量断崖下跌，模组压差拉大，整组电池提前报废。储能电站、户用储能追求超长循环，电解液配方、化成工艺全部围绕构建优质 SE 设计，优化 SE 性能是提升产品市场竞争力关键技术路线。

The compactness, stability and thickness of SEI films directly determine cell cycle life as a core interfacial factor. High-quality uniform, tough SEI resists cracking under anode deformation from repeated sodium intercalation, long-term blocks side reactions and minimizes irreversible sodium loss, enabling stable cycling over 3000 times with gentle capacity decay. Inferior brittle loose SEI breaks frequently during cycling; exposed carbon continuously reacts with electrolytes to consume active sodium, and repeated regeneration thickens films, raising cell resistance and heat generation. After thousands of cycles, capacity drops sharply, module voltage gaps widen and the whole battery pack fails prematurely. Energy storage power stations and household storage pursue ultra-long cycles; electrolyte formulas and formation processes are all designed to form high-quality SEI, and optimizing SEI performance is a core technical route to boost product competitiveness.