Sulfur defect engineering controls Li2S crystal orientation towards dendrite-free lithium metal batteries

Abstract Controlling nucleation and growth of Li is crucial to avoid dendrite formation for practical applications of lithium metal batteries. Li 2 S has been exemplified to promote Li transport, but its crystal orientation significantly influences the Li deposition behaviors. Here, we investigate the interactions between Li and various surface structures of Li 2 S, and reveal that the Li 2 S(111) plane exhibits the highest Li affinity and the lowest diffusion barrier, leading to dense Li deposition. Using sulfur defect engineering for Li 2 S crystal orientation control, we construct three-dimensional vertically oriented Li 2 S(111)@Cu nanorod arrays as a Li metal electrode substrate and identify a substrate-dependent Li nucleation process and a facet-dependent growth mode. Furthermore, we demonstrate the versatility of the Li 2 S(111)@Cu substrate when paired with two positive electrodes: achieving an initial discharge capacity of 138.8 mAh g –1 with 88% capacity retention after 400 cycles at 83.5 mA g –1 with LiFePO 4 , and an initial discharge capacity of 181 mAh g –1 with 80% capacity retention after 160 cycles at 60 mA g –1 with commercial LiNi 0.8 Co 0.1 Mn 0.1 O 2 positive electrode (4 mAh cm –2 ).