What are the surface roughness requirements for aluminum foil current collectors of sodium-ion batteries?

铝箔粗糙度 Ra 标准 0.2-0.6μm，需要均匀适度，不能过高或过低。粗糙度过低箔面过于光滑，涂层附着力不足，涂布、分切、循环中极易整片脱落，接触电阻大幅超标。粗糙度过高表面沟壑尖锐，涂布浆料厚薄不均，极片一致性变差；辊压、装配时凸起刺破隔膜引发内部短路，沟壑残留杂质持续触发电解液副反应，电芯胀气、自放电加剧。适中凹凸结构增大涂层接触面积，强化粘结、稳定导电。钠电池正负极统一使用铝箔，无需区分铜铝，管控标准统一，对比锂电池铜箔门槛更低，简化原材料加工流程，大幅降低电芯制造成本，适配大规模量产需求。

The standard surface roughness Ra of aluminum foil ranges from 0.2 to 0.6 μm, requiring uniform moderate texture without extreme values. Excessively smooth foil with low roughness suffers poor coating adhesion, leading to full delamination during coating, slitting and cycling and excessive contact resistance. Overly rough foil features sharp grooves that create uneven slurry thickness and poor electrode consistency. Protrusions pierce separators during calendering and assembly to cause internal short circuits, while residual impurities in grooves induce continuous electrolyte side reactions, aggravating cell swelling and self-discharge. Moderate concave-convex textures expand contact areas, strengthen adhesion and stabilize conductivity. Sodium-ion batteries apply aluminum foil to both cathodes and anodes with unified control standards. Compared with copper foil for lithium batteries, it has lower processing thresholds, simplifies raw material workflows and cuts cell production costs for mass manufacturing.