PNNL

Abstract

Lithium-ion sulfur batteries use non-metal materials as the anode to address safety concerns associated with lithium metal anode. However, polysulfide shuttle reactions still occur on the non-metal anode (such as graphite and Si), and result in limited battery efficiency. In this work, we used Al2O3 layers coated by atomic layer deposition (ALD) technique to suppress the shuttle reactions. With the optimal thickness of 2 nm Al2O3 coated on graphite anode, the Coulombic efficiency of the sulfur cathode was improved from 84% to 96% in the first cycle, and from 94% to 97% in the subsequent cycles. As a result, the discharge capacity of the sulfur cathode was increased to 550 mAh g-1 in the 100th cycle, as compared with 440 mAh g-1 when the pristine graphite anode was used. The Al2O3 passivation layer minimizes the formation of insoluble polysulfide (Li2S2, Li2S) on the surface of graphite anode and improves the efficiency and capacity retention of the graphite-sulfur batteries. The surface passivation strategy could also be used in other Li sulfur battery systems (with Li, Si, and Sn anodes), to minimize side reactions and enable high-performance and safe sulfur batteries.