KTFA as an interface‐stable and dendrite‐inhibiting additive in high‐performance lithium metal batteries

Abstract Lithium metal anode with a high theoretical capacity (3860 mAh g −1 ) is the most ideal anode for high‐energy density rechargeable batteries. However, lithium dendrite growth and unstable electrode/electrolyte interfaces have limited commercialization applications. Here, potassium trifluoroacetate (KTFA), as a functional additive, was introduced into the electrolytes. The K + adsorbed at the tip of the lithium metal anode surface forms a charge shielding effect at low concentrations, forcing Li + to deposit far from the tip, effectively regulating the behaviour and inhibiting the growth of lithium dendrites. Moreover, the TFA − anions with the lowest unoccupied molecular orbital (LUMO) energy levels can preferentially form a LiF‐rich and Li 2 O‐rich solid−electrolyte interphase (SEI) layer and stabilize the lithium electrode/electrolyte interface. Thus, Li||Cu cells have superior cycling stability for 1200 cycles and 800 cycles at 0.5 mA cm −2 and 1.0 mA cm −2 in the E3 electrolyte, respectively. Encouragingly, the Li||LiFePO 4 (LFP) full cell maintained greater capacity retention after 800 cycles at 2.0C. The Li||LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM811) full cell also retained an initial capacity of 87.04% after 500 cycles at 1.0C, and the practical 1.0 Ah Li||NCM811 pouch cell, with a capacity retention of 96.65% after 80 cycles, exhibited excellent cycle reversibility and potential for practical application. This work provides a simple and practical strategy for preparing high‐performance lithium metal batteries (LMBs).