Dynamic Ion Sieve as the Buffer Layer for Regulating Li+ Flow in Lithium Metal Batteries

Abstract How to realize uniform Li + flow is the key to achieve even Li deposition for lithium metal batteries (LMBs). In this study, a concept of dynamic ion sieve is proposed to design the buffer layer nearby Li anode surface to regulate Li + spatial arrangement by introducing tributylmethylphosphonium bis(trifluoromethanesulfonyl)imide (TMPB) into the carbonate electrolyte. The buffer layer induced by TMP + can adjust the velocity of arriving solvated Li + that gives solvated Li + sufficient time to redistribute and accumulate on Li anode surface, resulting in a uniform and higher concentrated Li + flow. Besides, TFSI − can participate in the generation of inorganic component‐rich solid electrolyte interphase (SEI) with Li 3 N, which can facilitate the Li + conductivity of SEI. Consequently, the stable and uniform Li deposition can be obtained, achieving the excellent cycling performance up to 1000 h at 0.5 mA cm −2 in the Li||Li symmetric cell. Besides, the Li||NCM622 full cell also possesses excellent cycling stability with a high‐capacity retention rate of 66.7% after 300 cycles.