Functionalized Silica‐Constructed Self‐Supporting Composite Separator for Lithium Metal Batteries

ABSTRACT

Lithium metal batteries (LMBs) are considered highly promising next‐generation energy storage systems owing to their exceptionally high theoretical specific capacity and ultralow electrochemical potential. Nevertheless, the practical deployment of LMBs is still severely restricted by the uncontrollable formation and propagation of lithium dendrites during repeated cycling. In this study, an organic‐inorganic composite separator was developed by blending polyvinylidene fluoride (PVDF) with two‐dimensional porous silica nanosheets (PSN) followed by electrospinning. The resulting membrane features a porous interconnected structure, a hierarchically porous architecture, and abundant oxygen‐containing functional groups on its surface. Benefiting from its unique structural characteristics, the composite separator presents outstanding comprehensive performance; it exhibits superior thermal stability without obvious thermal shrinkage even at 200°C, favorable electrolyte wettability, rapid ion transport capability, and a high porosity of 59.14%. Moreover, it can effectively homogenize lithium‐ion flux and induce the generation of a stable solid electrolyte interphase (SEI) layer, which efficiently restrains the uncontrolled growth of lithium dendrites. The assembled Li//Li symmetric cell achieves ultra‐long stable cycling over 2000 h at 0.25 mA ⋅ cm ⁻² , and the Li//LiFePO ₄ full cell maintains excellent discharge capacity with a capacity retention of 74.3% after 1500 cycles at 5C rate.