LiTaO3 또는 InF3의 혼합에 의한 전고체전지용 고체 전해질 Li5.3PS4.3Cl1.7의 계면 안정성 향상에 관한 연구

Abstract

Today, all-solid-state batteries(ASSBs) with solid electrolytes(SEs) are receiving a lot of attention as next-generation batteries. Solid electrolytes are chemically more stable than liquid electrolytes, can have higher energy densities, and can operate over a wide temperature range. In particular, sulfide-based solids electrolytes have the advantage of having good mechanical properties and high ionic conductivity, but they have the problem that unwanted side reactions may occur at the interface between the solid electrolyte and the electrode, which may deteriorate battery performance. In this work, to reduce the interfacial resistance, LiTaO3 coating material was simply mixed with the solid electrolyte to measure the effect of suppressing side reactions. To synthesize the solid electrolyte Li5.3PS4.3Cl1.7 and the mixing material LiTaO3, high-energy ball milling and wet milling methods were used, respectively. The structural characteristics of the prepared solid electrolytes were studied by powder X-ray diffraction. The LiTaO3 mixed solid electrolyte based ASSB showed a high discharge capacity of 177.3mAh/g in the initial cycle, whereas the bare solid electrolyte (Li5.3PS4.3Cl1.7) based ASSB showed a discharge capacity of 159.1mAh/g. To understand the side reactions, electrochemical impedance spectroscopy (EIS) analysis was performed after galvanostatic charging-discharging cycles. The EIS analysis confirmed that the side reaction between a solid electrolyte and a cathode has been effectively suppressed in LiTaO3 mixed solid electrolyte based ASSBs. Second, we prepared Li5.3PS4.3Cl1.7 mixed with InF3. We also confirm the structural properties using powder X-ray diffraction (XRD). Through the XRD pattern, it was observed that the argyrodite structure was maintained and only the intensity of the peak corresponding to InF3 increased. The optimized solid electrolyte based ASSB showed a higher initial discharge capacity of 172.8mAh/g and a coulombic efficiency of 78.54%, and the capacity retention rate was also measured to be better than bare solid electrolyte (Li5.3PS4.3Cl1.7) based ASSB.