无机涂层改善锂离子电池聚烯烃隔膜性能研究

为了提高锂离子电池用聚烯烃微孔膜的综合性能, 在商用Celgard膜表面涂布ZrO₂无机涂层, 粘结剂选用电池用聚偏氟乙烯。对比分析涂覆前后的隔膜发现, ZrO₂涂层可以显著提高Celgard膜的热尺寸稳定性和热熔化温度, 对提高锂离子电池安全性起到积极作用。同时无机涂层还能明显改善隔膜对电解液的浸润性, 复合隔膜具有更好的保液能力, 以涂有ZrO₂涂层的Celgard膜作为隔膜组装锂离子电池,可以显著提高长期充放电循环时电池容量保持率。

Inorganic Layer Coated Polyolefin Separator with High Performances for Lithium-ion Batteries

Inorganic layer-coated separator was prepared by coating the sides of a porous polyolefin membrane with ZrO₂ powder and polyvinylidene fluoride binder. The composite separator exhibits improved thermal stability at high temperatures without significant thermal shrinkage. Moreover, the separator has higher melt temperature. It is expected that the ZrO₂-coated separator in this study can be potential candidate as a separator for rechargeable lithium-ion batteries that require thermal safety. Due to the high hydrophilicity of the ZrO₂ powder and large surface area of the small particles, the separator shows good wettability in non-aqueous liquid electrolytes. Meanwhile, a higher amount of electrolyte solution is expected to be retained by the separator. By using the ZrO₂-coated separator, lithium-ion cell was assembled and its cycling performance is evaluated. The cells are proven to be having better capacity retention than the cells prepared with polyolefin membrane.