钠电池的密封工艺是什么？

What is the sealing process of sodium-ion batteries?

钠电池密封分为电芯单体密封与 PACK 整包密封两层防护体系，核心目的隔绝空气、水汽、粉尘，阻止电解液挥发、钠盐水解产气，从源头抑制电芯胀气、自放电加剧。单体电芯分三类密封方案：圆柱、方形铝壳采用滚槽加激光满焊工艺，焊缝连续无断点，配套防爆阀一体化成型；软包铝塑膜电芯采用分段高温热封，精准控制热封温度、压力、时长，封边无气泡缝隙，预留排气边适配多道排气工序；PACK 壳体密封使用防水密封胶、弹性橡胶胶条、聚氨酯灌封胶填充接缝。密封长效性能需通过高低温循环、盐雾老化验证，胶层不可出现脱胶、开裂。若密封失效，外界水汽渗入会与钠盐发生水解反应，持续生成氢气、二氧化碳，电芯内部压力上升出现鼓包，隔膜绝缘性能下降，模组压差持续拉大；户外储能、船舶等高湿场景对密封等级要求达到 IP67，密封工序后同步开展真空检漏，微量漏气电芯直接返工重封，保障全生命周期不漏液、不进水。

The sealing process of sodium-ion batteries consists of two protective layers: single cell sealing and whole PACK sealing. Its core purpose is to isolate air, moisture and dust, prevent electrolyte volatilization and sodium salt hydrolysis gas generation, and restrain cell swelling and aggravated self-discharge from the source. Three sealing schemes are adopted for single cells: cylindrical and square aluminum shells adopt rolling grooves plus full laser welding with continuous seamless welds and integrated explosion-proof valves; soft aluminum plastic film cells adopt segmented high-temperature heat sealing with precisely controlled temperature, pressure and duration, bubble-free sealing edges and reserved exhaust edges matching multiple exhaust procedures; PACK shell joints are filled with waterproof sealant, elastic rubber strips and polyurethane potting glue. The long-term sealing performance needs to pass high-low temperature cycle and salt spray aging verification without glue delamination or cracking. If sealing fails, external moisture penetrates and hydrolyzes sodium salts to continuously generate hydrogen and carbon dioxide, raising internal cell pressure and causing swelling, degrading separator insulation and widening module voltage difference. Outdoor energy storage and marine equipment require IP67 sealing grade. Vacuum leak detection is conducted after sealing procedures, and cells with tiny air leakage are directly re-sealed to ensure no liquid leakage or water ingress throughout the service life.