Interplay between Li3YX6 (X = Cl or Br) solid electrolytes and the Li metal anode

Abstract

The interplay between solid electrolytes and electrodes is of vital importance to the performance of allsolid-state Li batteries. Recently, halide superionic conductors have emerged as a new family of high-performance solid electrolytes, but their compatibility with Li metal, i.e., the anode with the highest theoretical capacity, has not been systematically studied. Here, we investigate the interaction between Li metal and two representative halide solid electrolytes: Li 3 YCl 6 and Li 3 YBr 6 . Both materials are found to form interphases with Li, similar to most solid electrolytes. However, the interphases observed here contain electronic conducting components, which are detrimental to their compatibility with Li. By elucidating this phenomenon, the present study provides guiding principles for improving the Li compatibility of halide solid electrolytes.

A cost-effective and humidity-tolerant chloride solid electrolyte for lithium batteries

“…First of all, the non-zero reduction potential of LZC indicates that this material is unstable against Li reduction. Besides, considering that the reduction products are suggested to contain both the electronic conductor (Zr) and ionic conductor (LiCl), the reaction between LZC and Li metal may not be selflimited, but would likely proceed continuously, similar to the situation for Li 3 YCl 6 and Li 3 InCl 6 50,51 . This scenario is supported by the electrochemical measurements carried out in the Li | LZC | Li symmetric cell, whose Li stripping/plating voltages increase constantly without any sign of stabilizing and reach the instrument limit of 5 V in only 88 h (Supplementary Fig.…”

“…13b−c), further confirming the severe reaction between these two materials. Consequently, like other chloride solid electrolytes 50,51 , LZC should not be in direct contact with Li in all-solid-state cells. Nevertheless, this material does exhibit a rather high oxidation potential beyond 4 V, which could entail a good compatibility with the 4 V-class cathodes.…”

A Series of Ternary Metal Chloride Superionic Conductors for High‐Performance All‐Solid‐State Lithium Batteries

“…Recently, due to the development of superionic conductor such as Li 3 YCl 6 [14] and Li 3 InCl 6 , [19,20] metal halide SSEs have received renewed attention. [21][22][23][24][25][26][27][28][29][30][31][32][33][34] Until now, only a few metal chloride SSEs have achieved high room-temperature (RT) ionic conductivities over 10 −3 S cm −1 , including Li 3 InCl 6 , [19,20] Zr-doped Li 3 MCl 6 (M = Y, Er, Yb, In), [21,26,27,33] Li 3 Y 1−x In x Cl 6 , [22] Li x Sc Cl 3+x , [23] Li 2 Sc 2/3 Cl 4 , [24] etc. In the search for new metal chloride SSEs, a better understanding of the relationship between structure and ionic conductivity is highly demanded.…”

Coupling a Three-Dimensional Nanopillar and Robust Film to Guide Li-Ion Flux for Dendrite-Free Lithium Metal Anodes

“…Among them, constructing a uniform artificial SEI in place of the spontaneously formed SEI is a straightforward method to stabilize the Li metal anodes. − For instance, the functionalized artificial SEI layers have the advantages of alleviating side reactions, providing fast Li-ion channels, and guiding homogeneous Li-ion flux. However, the flexible but low-stiffness organic SEI can hardly withstand the piercing of dendrites due to the inherently uneven Li surface. , In addition, the robust inorganic SEI is rigid enough to block the Li dendrites but failed to adapt to the volume expansion of the Li metal anodes during the long-term cycling. , …”

“…However, the flexible but low-stiffness organic SEI can hardly withstand the piercing of dendrites due to the inherently uneven Li surface. 19,20 In addition, the robust inorganic SEI is rigid enough to block the Li dendrites but failed to adapt to the volume expansion of the Li metal anodes during the long-term cycling. 21,22 Considering the dendritic growth and volume expansion of Li metal anodes, 3D current collectors are deemed to be an advisable route.…”