A robust interface enabled by electrospun membrane with optimal resistance in lithium metal batteries

A uniform diffusion layer is essential for non-dendritic deposition of lithium in high-density lithium batteries. However, natural pristine solid electrolyte interface (SEI) is always porous and inhomogeneous because of repeated breakdown and repair cycles, whereas ideal materials with excellent mechanical property for artificial SEIs remain a challenge. Herein, a robust and stable interface is achieved by spinning soft polymer associated with few MoO₃ into fibers, and thus mechanical property of fibers other than materials determines mechanical performance of the interface which can be optimized by adjusting parameters. Furthermore, lithium deposited underneath the layer is enabled by constructing an optimal resistance to make the membrane serve as an artificial SEI rather than lithium host. As a result, dendrite-free lithium was observed underneath the membrane, and stable interface for long-term cycling was also indicated by EIS measurements. The lithium iron phosphate (LiFePO₄) full-cell with coated electrode demonstrated an initial capacity of 155.2 mAh g⁻¹, and 80% of its original capacity was retained after 500 cycles at 2.0 °C without any additive in carbonate-based electrolyte.