(352i) Highly Stable Lithium Metal Batteries Enabled By Regulating the Solvation of Lithium Ions in Nonaqueous Electrolytes

Safe and rechargeable lithium metal batteries have been difficult to
achieve because of the formation of lithium dendrites. Herein an emerging
electrolyte based on a simple solvation strategy is proposed for highly stable
lithium metal anodes in both coin and pouch cells. Fluoroethylene carbonate
(FEC) and lithium nitrate (LiNO₃) were concurrently introduced into
an electrolyte, thus altering the solvation sheath of lithium ions, and forming
a uniform solid electrolyte interphase (SEI), with an abundance of LiF and LiN_xO_y
on a working lithium metal anode with dendrite-free lithium deposition.
Ultrahigh Coulombic efficiency (99.96%) and long lifespans (1000 cycles) were
achieved when the FEC/LiNO3 electrolyte was applied in working batteries. The
solvation chemistry of electrolyte was further explored by molecular dynamics
simulations and first-principles calculations. This work provides insight into
understanding the critical role of the solvation of lithium ions in forming the
SEI and delivering an effective route to optimize electrolytes for safe lithium
metal batteries.

Fig. 1 Fluoroethylene carbonate (FEC) and lithium nitrate
(LiNO₃) were concurrently introduced into an electrolyte, thus
altering the solvation sheath of lithium ions and forming a uniform solid
electrolyte interphase (SEI). An abundance of LiF and LiN_xO_y
is formed on the working lithium metal anode and contributes to dendrite©\free
lithium deposition.

References:
[1] X. Q. Zhang,
X. Chen, et al, Angew. Chem. Int. Ed. 2018, 57, 5301.