钠电池的预充工艺是什么？

What is the pre-charging process of sodium-ion batteries?

预充是大容量叠片储能电芯专属化成前置工序，注液充分浸润完成后采用极小电流进行微量充电，不会完成完整充放电循环，核心缓解化成阶段集中产气鼓包问题，优化 SEI 钝化膜均匀度。预充电流远低于标准化成电流，仅补充少量电荷，提前在负极表面生成薄层基础 SEI 膜，分散化成过程电解液分解产气速率，避免大容量电芯内部瞬时气压过高撑破密封边。中小容量卷绕电芯产气量少，可直接省略预充工序；200Ah 以上方形叠片、高压实密度储能电芯强制配套预充流程。预充带来多重性能增益：降低初次不可逆容量损耗，提升首效；钝化膜厚薄均匀，减少循环过程内阻增幅；电芯化成阶段无明显鼓包，良率提升。预充后静置一定时长再进入标准化成，工业产线将预充、化成、排气串联自动化流转，全程恒温控温规避温度波动干扰界面成膜效果。

Pre-charging is a dedicated pre-formation procedure for large-capacity stacked energy storage cells. After sufficient liquid injection and infiltration, tiny current is adopted for micro-charging without completing full charge-discharge cycles. Its core function is to relieve concentrated gas generation and swelling during formation and optimize the uniformity of SEI passivation films. The pre-charging current is far lower than the standard formation current, only supplementing a small amount of charge to generate thin basic SEI films on anode surfaces in advance, disperse the gas production rate from electrolyte decomposition during formation and prevent excessive instantaneous internal pressure of large-capacity cells from breaking sealing edges. Small and medium-sized wound cells generate little gas and can directly skip pre-charging, while square stacked cells above 200Ah and high-compaction energy storage cells must be equipped with pre-charging procedures. Pre-charging brings multiple performance gains: reducing initial irreversible capacity loss and raising initial Coulombic efficiency; forming uniform passivation films to slow internal resistance growth during cycling; eliminating obvious cell swelling during formation and improving yield. Cells stand for a certain period after pre-charging before entering standard formation. Industrial production lines realize automatic serial circulation of pre-charging, formation and exhaust with constant temperature control throughout the process to avoid temperature fluctuations interfering with interfacial film formation.