钠电池极片的烘干工艺有什么作用？

What are the functions of the drying process of electrodes for sodium-ion batteries?

涂布后分段梯度烘干是关键热处理工序，承担四大核心功能支撑电芯长期稳定循环。第一彻底脱除溶剂与水分，微量残留水分会在注液后与钠盐发生水解反应产气，造成电芯胀气报废，有机溶剂残留会持续引发副反应加速容量衰减；第二固化粘结剂交联结构，分段高温促使粘结剂充分交联固化，大幅提升涂层与铝箔附着力，杜绝辊压、分切过程涂层脱落；第三优化极片内部孔隙结构，缓慢升温避免涂层表层快速结皮，极片微孔分布均匀，电解液浸润效率提升，电芯内阻显著降低；第四控制极片形变，低温预热、中温固化、高温干透三段温控，涂层均匀收缩，杜绝翘曲褶皱，保障后续辊压、分切尺寸精度。烘干后极片水分必须控制在 ppm 级，是电芯注液前强制质检项目，水分超标电芯直接隔离报废，防止批量储能模组出现自放电异常、压差过大故障。

Segmented gradient drying after coating is a key heat treatment procedure with four core functions supporting long-term stable cell cycling. First, complete removal of solvents and moisture: trace residual moisture undergoes hydrolysis with sodium salts after liquid injection to generate gas and scrap cells, while residual organic solvents trigger continuous side reactions and accelerate capacity fading. Second, cross-link and cure binders: segmented high temperature fully cures binders to drastically boost coating adhesion on aluminum foil and prevent peeling during calendering and slitting. Third, optimize internal electrode pore structure: slow temperature rise avoids rapid crust formation on coating surfaces, achieves uniform micropore distribution, improves electrolyte infiltration efficiency and greatly reduces cell internal resistance. Fourth, control electrode deformation: three-stage temperature control (low-temperature preheating, medium-temperature curing, high-temperature thorough drying) enables uniform coating shrinkage, eliminates warpage and wrinkles and guarantees dimensional precision for subsequent calendering and slitting. Electrode moisture after drying must be controlled at ppm level as a mandatory quality inspection before cell liquid injection. Cells with excessive moisture are directly isolated and scrapped to avoid abnormal self-discharge and overvoltage difference faults of batch energy storage modules.