Countersolvent Electrolytes for Lithium‐Metal Batteries

Abstract

Development of electrolytes that simultaneously have high ionic conductivity, wide electrochemical window, and lithium dendrite suppression ability is urgently required for high‐energy lithium‐metal batteries (LMBs). Herein, an electrolyte is designed by adding a countersolvent into LiFSI/DMC (lithium bis(fluorosulfonyl)amide/dimethyl carbonate) electrolytes, forming countersolvent electrolytes, in which the countersolvent is immiscible with the salt but miscible with the carbonate solvents. The solvation structure and unique properties of the countersolvent electrolyte are investigated by combining electroanalytical technology with a Molecular Dynamics simulation. Introducing the countersolvent alters the coordination shell of Li+ cations and enhances the interaction between Li+ cations and FSI− anions, which leads to the formation of a LiF‐rich solid electrolyte interphase, arising from the preferential reduction of FSI− anions. Notably, the countersolvent electrolyte suppresses Li dendrites and enables stable cycling performance of a Li||NCM622 battery at a high cut‐off voltage of 4.6 V at both 25 and 60 °C. This study provides an avenue to understand and design electrolytes for high‐energy LMBs in the future.

Robust Artificial Solid‐Electrolyte Interfaces with Biomimetic Ionic Channels for Dendrite‐Free Li Metal Anodes

“…In response to these challenges, various strategies, such as the use of different solvents, [ 10–12 ] the optimization of Li salt concentrations, [ 13–15 ] the addition of functionalized additives, [ 16–18 ] and the design of electrolyte nanostructures, [ 19–21 ] have been proposed to construct a stable SEI film on the surface of Li metal anodes. These modifications of the in‐situ formed SEI films could enable uniform Li deposition and suppress Li dendrite growth in initial cycles.…”

An Inorganic‐Rich Solid Electrolyte Interphase for Advanced Lithium‐Metal Batteries in Carbonate Electrolytes

“…The unique solvation structure of high‐concentrated nitrate electrolytes also increases the viscosity of the bulk electrolyte and changes the SEI compositions on the anodes, as demonstrated in the “water‐in‐salt” aqueous electrolytes [48, 49] as well as highly concentrated organic electrolytes [40, 50] . Therefore, antisolvents need to be added into these highly concentrated organic electrolytes in order to reduce their viscosities [41, 51] . In this work, we added a small amount of 4.0 M LiNO 3 ‐DMSO solution into dilute carbonate electrolytes to leverage merits of both electrolytes while minimizing their weaknesses.…”

Spatially Controlled Lithium Deposition on Silver‐Nanocrystals‐Decorated TiO2 Nanotube Arrays Enabling Ultrastable Lithium Metal Anode

“…In the past decade, many strategies have been proposed to solve the crucial problems of Li anode, such as optimizing electrolyte composition, [ 12–19 ] engineering solid‐electrolyte/solid interface layers, [ 20–24 ] and modifying the substrate or host structures for Li metal. [ 25–31 ] Among these routes, the construction of Li host structures especially for 3D electrodes has received great interest because it's an effective way to regulate Li deposition, suppress Li dendrites, and reduce the local current density.…”