钠电池极片的涂布工艺有哪些要求？

What are the requirements for the coating process of electrodes for sodium-ion batteries?

涂布工序将均匀浆料连续涂覆在铝箔集流体表面，形成厚度可控活性涂层，工艺精度直接决定电芯容量、内阻一致性，存在四大硬性管控标准。第一厚度均匀性，极横向、纵向首尾涂层厚度偏差严格受控，厚薄不均会造成同批次电芯容量分层，PACK 模组运行压差持续拉大；第二表面外观零缺陷，涂层无针孔、划痕、颗粒团聚、露铝、掉粉瑕疵，保证界面导电稳定无局部极化；第三涂层附着力达标，胶带剥离测试无大面积涂层脱落，避免辊压、分切、卷绕工序大面积掉粉报废；第四工艺参数匹配，涂布速度、烘箱分段温度根据浆料固含量、粘度实时调整，双面涂布正负极对齐误差控制在极小范围。水系浆料烘干温差更低，油系涂布产线必须配套废气回收处理装置，符合环保排放规范。涂布精度不达标会导致成品电芯性能离散度超标，储能电站同组电池衰减速度不一致，缩短整套储能系统使用寿命。

The coating procedure continuously coats uniform slurries onto aluminum foil current collectors to form active coatings with controllable thickness. Process precision directly determines cell capacity and internal resistance consistency with four rigid control standards. First, thickness uniformity: thickness deviation of coatings at horizontal, vertical, head and tail positions is strictly regulated. Uneven thickness causes capacity stratification of cells from the same batch and continuously widened voltage difference during PACK operation. Second, defect-free surface: coatings are free of pinholes, scratches, particle agglomeration, exposed aluminum and powder shedding to guarantee stable interfacial conduction without local polarization. Third, qualified coating adhesion: no large-area coating peeling in tape peeling tests to avoid massive powder shedding and rejection during calendering, slitting and winding. Fourth, matched process parameters: coating speed and segmented oven temperatures are adjusted in real time according to slurry solid content and viscosity, with tiny alignment error for double-sided cathode and anode coating. Water-based slurries require lower drying temperature differences, while oil coating lines must be equipped with waste gas recovery devices to meet environmental emission standards. Substandard coating precision leads to excessive performance dispersion of finished cells, inconsistent fading speed of batteries in the same energy storage station pack and shortened service life of the whole storage system.