Fluorine‐Free Noble Salt Anion for High‐Performance All‐Solid‐State Lithium–Sulfur Batteries

Abstract

Amongst post‐Li‐ion battery technologies, lithium–sulfur (Li–S) batteries have captured an immense interest as one of the most appealing devices from both the industrial and academia sectors. The replacement of conventional liquid electrolytes with solid polymer electrolytes (SPEs) enables not only a safer use of Li metal (Li°) anodes but also a flexible design in the shape of Li–S batteries. However, the practical implementation of SPEs‐based all‐solid‐state Li–S batteries (ASSLSBs) is largely hindered by the shuttling effect of the polysulfide intermediates and the formation of dendritic Li° during the battery operation. Herein, a fluorine‐free noble salt anion, tricyanomethanide [C(CN)3−, TCM−], is proposed as a Li‐ion conducting salt for ASSLSBs. Compared to the widely used perfluorinated anions {e.g., bis(trifluoromethanesulfonyl)imide anion, [N(SO2CF3)2)]−, TFSI−}, the LiTCM‐based electrolytes show decent ionic conductivity, good thermal stability, and sufficient anodic stability suiting the cell chemistry of ASSLSBs. In particular, the fluorine‐free solid electrolyte interphase layer originating from the decomposition of LiTCM exhibits a good mechanical integrity and Li‐ion conductivity, which allows the LiTCM‐based Li–S cells to be cycled with good rate capability and Coulombic efficiency. The LiTCM‐based electrolytes are believed to be the most promising candidates for building cost‐effective and high energy density ASSLSBs in the near future.

Nonfluorinated Ionic Liquid Electrolytes for Lithium Metal Batteries: Ionic Conduction, Electrochemistry, and Interphase Formation

“…[ 35,36 ] The formation of such species can be supported by the observed graphitic sp 2 carbon peak appearing at about ≈0.8 eV lower that CC/CH peak (Figure 6d), possibly indicating the complete reduction of TCM − anion as supported by our DFT calculations (see Figure 3b) and also previously proposed by Zhang et al. [ 37 ]…”

Ionic‐Conducting and Robust Multilayered Solid Electrolyte Interphases for Greatly Improved Rate and Cycling Capabilities of Sodium Ion Full Cells

“…In the previous research, a dense NaF layer possessed a high modulus to restrain the volume change but suffered from a low ionic conductivity. [ 45,46 ] Considering the decomposition of FEC, the thick NaF may not be dense in the EC/DEC‐derived SEI due to the F‐containing organic component was generated simultaneously, [ 47 ] which could not prevent the continuous decomposition of the electrolyte, as the evidence by low CE and poorcyclic stability. The cycle performance of Bi/C in EC/DEC‐based electrolyte without FEC additive was conducted to clarify the role of FEC.…”

In Situ Construction of a LiF‐Enriched Interface for Stable All‐Solid‐State Batteries and its Origin Revealed by Cryo‐TEM

“…[3,4] The typical issue is addressed through various strategies, for example, the interfacial SEI engineering, [5,6] stable hosts construction, [7,8] and solid electrolyte design. [9,10] Among the strategies, the solid state electrolytes, particularly the solid polymer electrolytes (SPEs) for LMBs, have gained tremendous interest for many decades. [9,[11][12][13] A range of advantages from SPEs, including their satisfactory mechanical properties, high cathodic stability, inexpensive cost, low gravimetric density, and accessibility toward large-scale manufacturing process, [14][15][16][17][18][19] The morphologies of the normal Li/PEO interface are characterized and shown in Figure 1c-e.…”

“…[9,10] Among the strategies, the solid state electrolytes, particularly the solid polymer electrolytes (SPEs) for LMBs, have gained tremendous interest for many decades. [9,[11][12][13] A range of advantages from SPEs, including their satisfactory mechanical properties, high cathodic stability, inexpensive cost, low gravimetric density, and accessibility toward large-scale manufacturing process, [14][15][16][17][18][19] The morphologies of the normal Li/PEO interface are characterized and shown in Figure 1c-e. The cross-sectional image clearly shows many fine particles in the interface that may be the by-product of parasitic reactions between Li and PEO ( Figure 1c).…”