Construction of Ionic Conductive Electrode/ Electrolyte Interphases via Li + Coordination Regulator for 4.7 V Li/ LiNi 0.9 Co 0.05 Mn 0.05 O 2 Batteries

Abstract Lithium metal batteries (LMBs) using high‐voltage nickel‐rich layered cathode (LiNi x Co y Mn 1‐x‐y O 2 , NCM, x≥ 0.9), though delivering high energy density, suffer from critical instability of electrode/electrolyte interphases and structural degradation of NCM cathodes, causing rapid capacity fading. Here, trimethoxyboroxine (TMOBX) is used as a lithium‐ion coordination regulator in the commercial carbonate electrolyte to improve the cycling stability of LMBs at high voltage. Owing to the strong polarized B─O bonds, TMOBX not only prefers to interact with Li + because of the high electron density of O, but also attracts more PF 6 − in the solvation structure due to the positively charged B, resulting in robust and ionic conductive electrode/ electrolyte interphases rich in P─F compounds, B─O and B─F species. Moreover, TMOBX effectively eliminates HF in the electrolyte, all of which can avoid lithium dendrites, and suppress corrosion of LiNi 0.9 Co 0.05 Mn 0.05 O 2 (NCM90) and dissolution of transition metal ions. Consequently, the Li/Li symmetrical cells exhibit highly enhanced cycling stability of 500 h at 1 mA cm −2 , and the capacity retention of Li/NCM90 cells increases from 45.7% to 80.5% after 100 cycles at an ultrahigh cut‐off voltage of 4.7 V.