Authors: Ruirui Chang, Yingkang Liu, Yaguang Zhang, Yunyu Shi, Jingjing Tang, Zheng‐Long Xu, Xiangyang Zhou, Juan Yang
Published: 2025-03-18
Source: Full article
AbstractThe high crystallinity of poly(ethylene oxide)‐based solid polymer electrolytes (PEO‐based SPEs) is viewed as a key barrier to their ambient‐temperature performance. Conventional approaches to mitigate crystallinity necessitate elevated operation temperatures of 50–60 °C. Interestingly, this work indicates that the predominant factor limiting ambient‐temperature performance is the robust coordination between lithium‐ion (Li+) and ether oxygen (EO), rather than the crystallinity. By rationally tailoring the Li+ concentration, this work effectively weakens the coordination strength, thereby enhancing the ambient‐temperature electrochemical performance. An optimal SPE with EO: Li ratio of 9:1 exhibits remarkable ionic conductivity (1.76 × 10−4 S cm−1 at 35 °C), a high Li+ transference number (0.486 at 35 °C), and superior adhesion to electrodes in compression‐free pouch cells. The practical feasibility of the SPE is demonstrated in solid‐state Li‐LiFePO4 cells achieving a specific capacity of 149.66 mAh g−1 at 0.1 C and 35 °C and 90.5% capacity retention over 100 cycles. The electrolyte also exhibits compatibility with high‐voltage cathodes of LiNi0.6Co0.2Mn0.2O2 and LiNi0.8Co0.1Mn0.1O2 for high‐energy Li‐metal batteries. These new insights shed light on the rational regulation of SPEs in advanced solid‐state batteries.