Improving Room‐Temperature Li‐Metal Battery Performance by In Situ Creation of Fast Li<sup>+</sup> Transport Pathways in a Polymer‐Ceramic Electrolyte
Jing Yu, Guodong Zhou, Yueqing Li, Yuhao Wang, Dengjie Chen, Francesco Ciucci
Abstract
Abstract Composite polymer‐ceramic electrolytes have shown considerable potential for high‐energy‐density Li‐metal batteries as they combine the benefits of both polymers and ceramics. However, low ionic conductivity and poor contact with electrodes limit their practical usage. In this study, a highly conductive and stable composite electrolyte with a high ceramic loading is developed for high‐energy‐density Li‐metal batteries. The electrolyte, produced through in situ polymerization and composed of a polymer called poly‐1,3‐dioxolane in a poly(vinylidene fluoride)/ceramic matrix, exhibits excellent room‐temperature ionic conductivity of 1.2 mS cm −1 and high stability with Li metal over 1500 h. When tested in a Li|electrolyte|LiFePO 4 battery, the electrolyte delivers excellent cycling performance and rate capability at room temperature, with a discharge capacity of 137 mAh g −1 over 500 cycles at 1 C. Furthermore, the electrolyte not only exhibits a high Li + transference number of 0.76 but also significantly lowers contact resistance (from 157.8 to 2.1 Ω) relative to electrodes. When used in a battery with a high‐voltage LiNi 0.8 Mn 0.1 Co 0.1 O 2 cathode, a discharge capacity of 140 mAh g −1 is achieved. These results show the potential of composite polymer‐ceramic electrolytes in room‐temperature solid‐state Li‐metal batteries and provide a strategy for designing highly conductive polymer‐in‐ceramic electrolytes with electrode‐compatible interfaces.