Enhanced Electrochemical and Safety Performance of Lithium Metal Batteries Enabled by the Atom Layer Deposition on PVDF-HFP Separator

Lithium metal batteries, due to their unique advantages, such as being lightweight and having the lowest anode potential and the highest theoretical specific capacity, have been regarded as a promising candidate for next-generation electrical energy storage. Nevertheless, the development and practical application of lithium metal batteries has been seriously hindered by the safety issues induced by lithium dendrites. Here, the atom layer deposition (ALD) technique is introduced to fabricate Al₂O₃ on the surface of a PVDF-HFP membrane to endow it with higher thermal stability, great affinity with electrolytes, improved ion conductivity, and higher Young's modulus. Employing LiFePO₄|Li cells, the ALD100/PH separator imparts batteries with the best cycling performances and rate capacity among various separators. The SEM images of morphology after cycling indicate that ALD100/PH separators with extremely high Young's modulus and ion conductivity can suppress the growth of lithium dendrites. Moreover, the ALD100/PH separator shows more than 1300 h of stable operation at a current density of 0.5 mA cm^-2, exhibiting the capability against metallic lithium and the potential for application in the field of lithium metal batteries. Thus, this interesting ALD technique, capable of a feasible fabrication procedure and with desirable advantages, may be used to make commercial or as-prepared separators more advanced and may be a potential candidate for future rechargeable battery systems, including Li-S, Li-O₂, and other metal batteries.