Will Sulfide Electrolytes be Suitable Candidates for Constructing a Stable Solid/Liquid Electrolyte Interface?

Improving Cycling Stability of the Lithium Anode by a Spin-Coated High-Purity Li3PS4 Artificial SEI Layer

Controlling the composition and microstructure of the solid electrolyte interphase (SEI) layer is critical to improving the cycling stability of the high-energy-density lithium-metal electrode. It is a quite tricky task to control the properties of the SEI layer which is conventionally formed by the chemical reactions between a Li metal and the additives. Herein, we develop a new route to synthesize a lithium-compatible sol of the sulfide electrolyte Li₃PS₄, so that a Li₃PS₄ artificial SEI layer with a controllable nanoscale thickness and high phase purity can be prepared by spin-coating. The layer stabilizes the lithium/electrolyte interface by homogenizing the Li-ion flux, preventing the parasitic reactions, and alleviating concentration polarization. Consequently, a symmetrical cell with the Li₃PS₄-modified lithium electrodes can achieve stable lithium plating/stripping for 800 h at a current density of 1 mA cm^-2. The Li-S batteries assembled with the Li₃PS₄-protected Li anodes show better capacity retention than their bare Li counterparts, whose average decay rate from the 240th cycle to the 800th cycle is only 0.004%/cycle. In addition, the Li₃PS₄ layer improves the rate capacity of the batteries, significantly enhancing the capacity from 175 to 682 mA h g^-1 at a 2 C rate. The spin-coated Li₃PS₄ artificial SEI layer provides a new strategy to develop high-performance Li metal batteries.

Stabilizing Interface between Li2S-P2S5 Glass-Ceramic Electrolyte and Ether Electrolyte by Tuning Solvation Reaction

Using solid-liquid hybrid electrolytes is an effective strategy to overcome the large solid/solid interfacial resistance in all-solid-state batteries and the safety problems in liquid batteries. The properties of the solid/liquid electrolyte interphase layer (SLEI) are essential for the performance of solid-liquid hybrid electrolytes. In this work, the solvation reactions between Li₂S-P₂S₅ glass-ceramic solid electrolytes (SEs) and ether electrolytes were studied, and their influence on the SLEI was examined. Although 1,2-dimethoxyethane (DME) reacted with the Li₂S-P₂S₅ glass-ceramic SE to form a dense SLEI, 1,3-dioxolane (DOL) severely corroded the SE, resulting in a loose SLEI. Consequently, a stable SLEI formed with DME. Using a combination of the Li₂S-P₂S₅ glass-ceramic SE and the DME-based liquid electrolyte (LE), stable lithium plating/stripping cycles over 1000 h and a hybrid Li-S battery that retained a specific capacity of 730 mAh g^-1 after 200 cycles were demonstrated. The knowledge of the reactions between the sulfide electrolytes and the organic LEs is instructive for the design of stable sulfide-liquid hybrid electrolytes for advanced batteries.