Kinetics of Interfacial Lithium-ion Transfer between a Graphite Negative Electrode and a Li2S-P2S5 Glassy Solid Electrolyte (Supporting Information)

All-solid-state lithium-ion batteries that use sulfide solid electrolytes have attracted much attention due to their high safety and wide electrochemical window. In this study, highly oriented pyrolytic graphite (HOPG) and 75Li2S-25P2S5 (mol%) glass were used as a model graphite negative electrode and a sulfide solid electrolyte, respectively. Interfacial lithium-ion transfer between 75Li2S-25P2S5 glass and the HOPG electrode was studied by AC impedance spectroscopy measurements. The activation energy of the interfacial lithium-ion transfer was estimated to be around 37 kJ mol−1, which was much smaller than that at the interface between organic liquid electrolytes and HOPG electrode, indicating that the lithium-ion transfer at the interface between 75Li2S-25P2S5 glass and HOPG electrode proceeded quite rapidly. Furthermore, surface deposition of TiO2 and surface oxidation on HOPG electrodes were performed using the atomic layer deposition (ALD) method. Interfacial lithium-ion transfer between 75Li2S-25P2S5 glass and ALD-modified-HOPG electrodes was also investigated. The activation energies of the interfacial lithium-ion transfer were slightly higher than that of HOPG, but the resistance of the charge-transfer process was lower, indicating that the affinity of the HOPG electrode for the glass electrolyte was improved by surface modification.

全固态锂离子电池，采用硫化物固态电解质，因其卓越的安全性及宽广的电化学窗口而备受瞩目。本研究中，以高度取向的气相沉积石墨（HOPG）和75Li2S-25P2S5（摩尔比）玻璃分别作为模型石墨负极和硫化物固态电解质。通过交流阻抗谱测量法，对75Li2S-25P2S5玻璃与HOPG电极之间的界面锂离子传输进行了研究。界面锂离子传输的活化能估算约为37 kJ mol−1，远低于有机液体电解质与HOPG电极界面处的活化能，这表明75Li2S-25P2S5玻璃与HOPG电极界面处的锂离子传输过程进行得相当迅速。此外，采用原子层沉积（ALD）方法在HOPG电极上进行了TiO2的表面沉积和表面氧化处理。对75Li2S-25P2S5玻璃与ALD改性HOPG电极之间的界面锂离子传输也进行了研究。界面锂离子传输的活化能略高于HOPG，但电荷转移过程的电阻更低，这表明通过表面改性，HOPG电极对玻璃电解质的亲和性得到了提升。