Quasi-solid electrolytes with tailored lithium solvation for fast-charging lithium metal batteries

Using quasi-solid electrolytes (QSEs) can make lithium metal batteries (LMBs) considerably safer. However, formulating QSEs with rate capabilities rivaling those of liquid electrolytes is extremely difficult. Herein, we develop a QSE characterized by safety, high conductivity above 2 x 10(-3) S cm(-1), and high lithium-ion transference number (t(Li+)) above 0.8. Computations and experiments reveal that these characteristics are achieved by adjusting the Li+ solvation through a weak interaction with the polymer skeleton and strong coordination with NO3-. The further inclusion of fluoroethylene carbonate leads to the formation of a Li3N- and LiF-rich solid electrolyte interphase on the lithium metal. Consequently, QSE-based LMBs are capable of fast charging and high-power density, as well as stable and long cycling. By adjusting Li+ solvation and lithium metal stability, this work rationally develops QSEs for fast-charging LMBs.