Lithiophilic‐Gradient, Li+ Supplementary Interphase Design for Lean Lithium Metal Batteries

The practicability of anode-less/free lithiummetal batteries (LMBs) is impeded by unregulated dendrite formation on thedeposition substrate. Herein, this study presents a lithiophilic-gradient, layer-stacked interfacial design for the lean lithium metal battery (LLMB) model. Engineered via a facile wet-chemistry approach, the high entropy metalphosphide (HEMP) particles with tunable lithiophilic species are dispersedwithin reduced graphene oxide (RGO). Moreover, a poly (vinylidene fluoride co-hexafluoropropylenepolymer) (PVDF-HFP), blended with molten Li at the tailorable amounts, forms aLi supplementary top layer through a layer-transfer printing technique. Theintegrated layer (HEMP@RGO-MTL@PH) not only regulates the dendrite-free lithiumdeposition towards the Cu substrate up to 10 mAh cm-2, but also maintains robust cyclability of the symmetric cell at 5 mA cm-2 even under 83% depth of discharge. As pairing the modified Cu foil with the LiNi0.8Mn0.1Co0.1O2 cathode (NCM811, 16.9 mg cm-2, double sided, N/P ratio of 0.21) in the 200 mAh pouch cell, achieves gravimetric energy densities of 414.7 Wh kg-1, power output of 977.1 W kg-1, as well as highly reversible phasic evolutionmonitored in operando. This gradient interfacial strategy can promotethe commercialization of energy/power-dense energy storage solutions.