Abstract:
The active materials used in current LIBs fall short in energetic terms due to their limited uptake of Li, so further development of these materials is needed. In contrast to the insertion materials usually used in the LIBs, alloy materials are not restricted by the sites in the host structure and have demonstrated a high energy storage capacity. Among them, Silicon is considered the most promising due to its significant specific capacity (e.g., 3579 mAh/g) in comparison with that of graphite (i.e., conventional anode material with 372 mAh/g), the great abundance on the earth’s crust and its low working potential of 0.3 V. Nevertheless, Si presents a poor cycling performance due to significant volume expansion, unstable solid electrolyte interphase (SEI), and other side reactions during cycling. A further understanding of the Si-Li alloy reaction is still needed to overcome these challenges. Accordingly, some authors have reported solutions to reduce the capacity fading for liquid electrolytes (LEs), such as adding coatings, binders, nanocarbons, mixtures with graphite, etc.
In this work, a solid-state system has been designed to study the silicon anode alloy reaction with Li to complete the already available information in liquid-state and bring some advantages. Herein, pure Si nanowires (SiNWs) fabrics, produced from gas-phase using Floating Catalyst Chemical Vapor Deposition (FCCVD) method, are studied as dry anodes without any additives/polymers in integration with a sulfide-based solid electrolyte (Li10SnP2S12). To further understand alloying propagation in the dry Si electrode, the electrochemical characteristics of the SiNW electrodes were investigated in half-cells using various techniques, including galvanostatic charge/discharge, scanning electron microscopy, and impedance spectroscopy. Cross-sectional electron microscopy was also used to monitor the microstructural changes in the SiNWs during and after the alloying process.
