钠电池的排气工艺是什么？

What is the exhaust process of sodium-ion batteries?

电芯化成、长期循环过程中电解液分解会生成二氧化碳、微量氢气等副产气体，气体堆积挤压极片、阻隔电解液浸润，排气工艺定向排出内部积气，分为预排气与二次排气两道工序适配不同封装类型。软包电芯排气流程：化成产气后打开预留封边，负压抽走内部气体，同步带出少量损耗电解液，完成后复热密封；硬壳圆柱、方形电芯依靠防爆阀被动泄压，量产阶段增设工艺孔主动排气，排气完成封堵焊死。工艺核心管控两项指标：一是气体抽取彻底，电芯内部气压恢复常压；二是排气后不破坏整体密封结构，杜绝外界水汽反向渗入。排气不足会导致极片贴合松散，离子传导通道受阻，电芯内阻逐月上涨，容量快速衰减；充分排气后极片紧密贴合电解液，接触面积最大化，循环寿命显著提升。大容量软包储能电芯必须执行多次排气工序，铝壳电芯仅能依靠防爆阀被动泄压，无二次排气条件，配方层面需减少产气副反应匹配硬壳封装特性。

By-products such as carbon dioxide and trace hydrogen will be generated from electrolyte decomposition during cell formation and long-term cycling. Accumulated gas squeezes electrodes and blocks electrolyte infiltration. The exhaust process discharges internal accumulated gas in a targeted manner, divided into pre-exhaust and secondary exhaust procedures for different packaging types. Exhaust flow for soft-pack cells: after gas generation during formation, reserved sealing edges are opened to extract internal gas under negative pressure, a small amount of consumed electrolyte is taken away simultaneously, and heat sealing is repeated afterwards. Hard-shell cylindrical and square cells rely on explosion-proof valves for passive pressure relief, with process holes added for active exhaust during mass production and sealed and welded after exhaust completion. Two core indicators are controlled: thorough gas extraction to restore normal internal cell pressure, and intact overall sealing structures after exhaust to prevent reverse penetration of external moisture. Insufficient exhaust leads to loose electrode lamination, blocked ion transport channels, monthly rising internal resistance and rapid capacity fading. Complete exhaust enables tight electrode-electrolyte contact with maximized contact area and remarkably extended cycle life. Multiple exhaust procedures are mandatory for large-capacity soft-pack energy storage cells, while aluminum-shell cells only support passive pressure relief via explosion-proof valves without secondary exhaust, so formulas must optimize to reduce gas-producing side reactions to match hard-shell packaging characteristics.