钠电池的二次注液工艺是什么？

What is the secondary liquid injection process of sodium-ion batteries?

二次注液仅适配软包铝塑膜电芯，硬壳铝壳电芯注液孔焊死无法复充电解液，是大容量长循环储能软包配套核心工序。电芯初次注液、负压排气过程中会伴随电解液微量损耗，极片微孔吸附也会消耗部分液态离子介质，导致电芯内部电解液总量不足，离子传导介质短缺会限制电芯额定容量释放、缩短循环寿命。二次注液流程：打开预留注封边，高精度计量泵精准补足损耗电解液，完成后再次高温热封密封，同步执行真空检漏确保封边无漏气。该工艺精准匹配电芯设计电解液用量，保障极片、隔膜完全浸润，降低循环过程内阻上涨幅度，将电芯 3000 次循环容量保持率提升 5%~8。小型低速两轮车软包电芯电解液损耗低，无需二次注液；工商业大容量、长时储能软包电芯必须增设该工序，搭配精准称重管控单次补液量，杜绝注液过量造成内部产气空间不足引发鼓包。

Secondary liquid injection is only applicable to soft aluminum plastic film cells, as liquid injection holes of hard aluminum-shell cells are welded shut without electrolyte refilling. It is a core supporting procedure for large-capacity long-cycle energy storage soft packs. Tiny electrolyte loss occurs during initial liquid injection and negative-pressure exhaust, and partial liquid ion media are consumed by electrode micropore adsorption. Insufficient internal electrolyte restricts the release of rated cell capacity and shortens cycle life. Secondary liquid injection flow: open reserved injection sealing edges, accurately supplement lost electrolyte via high-precision metering pumps, repeat high-temperature heat sealing afterwards, and conduct vacuum leak detection simultaneously to ensure airtight sealing edges. This procedure accurately matches the designed electrolyte dosage of cells, guarantees full infiltration of electrodes and separators, slows internal resistance growth during cycling, and raises cell capacity retention after 3000 cycles by 5%~8. Small soft-pack cells for low-speed two-wheelers have low electrolyte loss and skip secondary injection, while large-capacity industrial & commercial long-duration energy storage soft packs must add this procedure, with precise weighing to control single supplementary dosage and avoid swelling caused by insufficient internal gas space from excessive electrolyte injection.