Anion-enrichment interface enables high-voltage anode-free lithium metal batteries

Abstract Aggressive chemistry involving Li metal anode (LMA) and high-voltage LiNi 0.8 Mn 0.1 Co 0.1 O 2 (NCM811) cathode is deemed as a pragmatic approach to pursue the desperate 400 Wh kg −1 . Yet, their implementation is plagued by low Coulombic efficiency and inferior cycling stability. Herein, we propose an optimally fluorinated linear carboxylic ester (ethyl 3,3,3-trifluoropropanoate, FEP) paired with weakly solvating fluoroethylene carbonate and dissociated lithium salts (LiBF 4 and LiDFOB) to prepare a weakly solvating and dissociated electrolyte. An anion-enrichment interface prompts more anions’ decomposition in the inner Helmholtz plane and higher reduction potential of anions. Consequently, the anion-derived interface chemistry contributes to the compact and columnar-structure Li deposits with a high CE of 98.7% and stable cycling of 4.6 V NCM811 and LiCoO 2 cathode. Accordingly, industrial anode-free pouch cells under harsh testing conditions deliver a high energy of 442.5 Wh kg −1 with 80% capacity retention after 100 cycles.