Simultaneous Stabilization of LiNi0.76Mn0.14Co0.10O2 Cathode and Lithium Metal Anode by Lithium Bis(oxalato)borate as Additive

摘要

The long-term cycling performance, rate capability, and voltage stability of lithium (Li) metal batteries with LiNi0.76Mn0.14Co0.10O2 (NMC76) cathodes is greatly enhanced by lithium bis(oxalato)borate (LiBOB) additive in the LiPF6-based electrolyte. With 2% LiBOB in the electrolyte, a Li vertical bar NMC76 cell is able to achieve a high capacity retention of 96.8% after 200 cycles at C/3 rate (1C=200mAg(-1)), which is the best result reported for a Ni-rich NMC cathode coupled with Li metal anode. The significantly enhanced electrochemical performance can be ascribed to the stabilization of both the NMC76 cathode/electrolyte and Li-metal-anode/electrolyte interfaces. The LiBOB-containing electrolyte not only facilitates the formation of a more compact solid-electrolyte interphase on the Li metal surface, it also forms a enhanced cathode electrolyte interface layer, which efficiently prevents the corrosion of the cathode interface and mitigates the formation of the disordered rock-salt phase after cycling. The fundamental findings of this work highlight the importance of recognizing the dual effects of electrolyte additives in simultaneously stabilizing both cathode and anode interfaces, so as to enhance the long-term cycle life of high-energy-density battery systems.