Low‐Enthalpy and High‐Entropy Polymer Electrolytes for Li‐Metal Battery

• Published in: Energy & environmental materials (Hoboken, N.J.) Vol. 7; no. 1; pp. 91 - n/a
• Main Authors: Zhang, Haitao, Wang, Yuchen, Huang, Junfeng, Li, Wen, Zeng, Xiankan, Jia, Aili, Peng, Hongzhi, Zhang, Xiong, Yang, Weiqing
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc 01.01.2024; Key Laboratory of Advanced Technologies of Materials,Ministry of Education,School of Materials Science and Engineering,Southwest Jiaotong University,Chengdu 610031,China%Institute of Electrical Engineering,Chinese Academy of Sciences,Beijing 100190,China
• Subjects: charge concentration gradient; Concentration gradient; Crystallization; Cycles; Electrolytes; Enthalpy; Entropy; Ion storage; Lithium; Lithium batteries; lithium dendrites; lithium‐metal battery; low‐enthalpy and high‐entropy; Molten salt electrolytes; Perovskites; polymer electrolyte; Polymers; Quantum dots; Solid electrolytes; lithium dendrites; low-enthalpy and high-entropy; charge concentration gradient; lithium-metal battery; polymer electrolyte
• DOI: 10.1002/eem2.12514
• ISSN: 2575-0356; 2575-0348

Ionic‐conductive solid‐state polymer electrolytes are promising for the development of advanced lithium batteries yet a deeper understanding of their underlying ion‐transfer mechanism is needed to improve performance. Here we demonstrate the low‐enthalpy and high‐entropy (LEHE) electrolytes can intrinsically generate remarkably free ions and high mobility, enabling them to efficiently drive lithium‐ion storage. The LEHE electrolytes are constructed on the basis of introducing CsPbI3 perovskite quantum dots (PQDs) to strengthen PEO@LiTFSI complexes. An extremely stable cycling >1000 h at 0.3 mA cm−2 can be delivered by LEHE electrolytes. Also, the as‐developed Li | LEHE | LiFePO4 cell retains 92.3% of the initial capacity (160.7 mAh g−1) after 200 cycles. This cycling stability is ascribed to the suppressed charge concentration gradient leading to free lithium dendrites. It is realized by a dramatic increment in lithium‐ion transference number (0.57 vs 0.19) and a significant decline in ion‐transfer activation energy (0.14 eV vs 0.22 eV) for LEHE electrolytes comparing with PEO@LiTFSI counterpart. The CsPbI3 PQDs promote highly structural disorder by inhibiting crystallization and hence endow polymer electrolytes with low melting enthalpy and high structural entropy, which in turn facilitate long‐term cycling stability and excellent rate‐capability of lithium‐metal batteries. Low‐enthalpy and high‐entropy effect promotes structural disorder degree of PEO, dissociation of Li salts, and generation of even more free Li+ ions in thermodynamic side, and in dynamic side, it facilitates rapid ion transfer, smooth charge distribution, and free lithium dendrites, which can intrinsically endow polymer solid‐state electrolytes remarkably free lithium ions and high mobility for next‐generation lithium‐metal battery.