钠电池的化成工艺是什么？

What is the formation process for sodium-ion batteries?

化成是注液浸润完成后电芯首次活化工序，通过小倍率缓慢充放电，可控诱导电解液在正负极表面生成均匀 SEI、CEI 钝化膜，是半成品转化为可正常使用成品的必经步骤。完整流程：恒温化成柜控温、低电流初次充电、静置、小电流放电、排气处理。全程严格限制电流、电压、充放电时长，防止界面膜厚薄不均、剧烈副反应大量产气。未经过化成的电芯界面极不稳定，每次充放电大量消耗电解液，容量断崖下跌无法正常使用。化成可提前筛选隐性缺陷电芯，微短路、浸润不良、轻微漏液产品会出现电压异常、温升超标，提前剔除降低成品不良率。储能长循环电芯会延长化成静置时间，优化 SEI 膜致密程度，提升 3000 次以上循环容量保持率，所有规格钠电池出厂前必须完成标准化化成工序。

Formation is the first cell activation procedure after liquid injection and infiltration. Slow low-rate charging and discharging controllably induce uniform SEI and CEI passivation films on cathode and anode surfaces, an indispensable step converting semi-finished products into usable finished cells. The complete flow covers temperature control in constant-temperature formation cabinets, low-current initial charging, standing, low-current discharging and gas exhaust treatment. Current, voltage and cycling duration are strictly limited throughout to avoid uneven interfacial film thickness and massive gas generation from violent side reactions. Cells without formation possess extremely unstable interfaces, consuming massive electrolyte every cycle with sharp capacity drop and normal operation failure. Formation screens defective cells in advance: products with micro-short circuits, poor infiltration and minor leakage show abnormal voltage and overheating for early rejection and lower finished reject rates. Long-cycle energy storage cells extend formation standing time to optimize SEI compactness and improve capacity retention after over 3000 cycles. All specifications of sodium-ion batteries must complete standardized formation before factory delivery.