Controllable etching Co/Fe-based Prussian blue analogue promoting uniform Li+ plating/stripping behavior for lithium metal batteries

The uncontrollable Li dendrite accumulation accompanied by low Coulombic efficiency severely hampers the sustainable and practical application of lithium metal batteries (LMBs). To tune the uneven Li⁺ flux caused by irregular pores on commercial separator and realize modulated Li⁺ plating/stripping behaviors, in this work, we report the modification of commercial polypropylene separator with etched Co/Fe-based Prussian blue analogue (PP@PBA-X, X represents the HCl etching time). The optimal PBA-4 with acid etching for 4 h possesses regulated micro-/meso-/macro-porous structure, which ensures homogeneous Li⁺ flow of PP@PBA-4 with high Li⁺ transference number of 0.76 and further hinders the growth of Li dendrites. With the assistance of PP@PBA-4, the Li||Li cell shows stable cycling performance for 500 h at 1 mA cm⁻² with fixed specific capacity of 1 mAh cm⁻², while the full Li-S battery with limited Li supply delivers favorable cycling stability for almost 430 cycles with 60 % capacity retention and high Coulombic efficiency of 99.95 % at current density of 500 mAg⁻¹.