What is the porosity of separators for sodium-ion batteries?

隔膜孔隙率是内部微孔总容积占隔膜整体体积百分比，量产标准 35%-50%，控制电解液吸附量与离子传导效率。隔膜核心作用隔绝正负极、导通钠离子，全部离子传输依靠微孔完成。孔隙过低微孔稀缺，电芯内阻升高、快充变差、大倍率极化严重；孔隙过高基材机械强度、抗穿刺能力大幅下滑，极片金属毛刺、活性颗粒易穿透形成微短路，加剧自放电，极端情况热失控起火。孔隙必须和孔径、厚度协同匹配，高孔隙搭配细小均匀微孔兼顾导电与安全。陶瓷涂布隔膜可同步提升孔隙与机械强度，是大容量储能电芯主流选材，稳定批量电芯一致性，延长循环使用寿命。

Separator porosity is the volume percentage of internal micropores in separators, with a mass production standard of 35%–50%, controlling electrolyte absorption and ion transmission efficiency. Separators isolate cathodes and anodes while conducting sodium ions entirely through micropores. Insufficient porosity creates scarce ion channels, raising internal resistance, weakening fast charging and causing severe polarization under high rates. Excess porosity drastically reduces mechanical strength and puncture resistance; metal burrs and active particles easily penetrate to form micro-short circuits, aggravating self-discharge and even thermal runaway. Porosity must coordinate with pore size and thickness. High porosity paired with tiny uniform micropores balances conductivity and safety. Ceramic-coated separators simultaneously improve porosity and mechanical strength, the mainstream choice for large-capacity energy storage cells to guarantee batch consistency and extend cycle life.