When audience takes stage: Pseudo-localized-high-concentration electrolyte with lithium nitrate as the only salt enables lithium metal batteries with excellent temperature and cathode adaptability

Abstract

A new concept for pseudo-localized-high-concentration electrolytes (PLHCE) is developed using cheap and less corrosive lithium nitrate as the single lithium salt to improve the electrochemical performance of the lithium metal batteries with excellent temperature and cathode adaptability. Unlike conventional localized high-concentration electrolytes, a small number of the diluent molecules involved in the solvation structure by lithium nitrate and triethyl phosphate (TEP) promote the formation of an organic-inorganic composite solid electrolyte interface (SEI) layer. A good balance is achieved in terms of the mechanical properties of the SEI layer. A high coulombic efficiency of more than 98% for the Li||Cu cell and 1000 h of long-term cycling for the Li||Li cell is exhibited. Assisted with the PLHCE strategy, the Li||LFP cells display excellent performance at both room and high temperatures, and the Li||NCM523 cells with a high working voltage exhibit good electrochemical stability as well. Moreover, alternative solvents are selected as the pseudo-diluents, which proves the general applicability of the PLHCE approach. This work provides an innovative concept to use the solubility difference to manipulate the solvation structure, which paves a new but simple way to design advanced electrolytes for lithium secondary batteries.