Metal–Organic Coordination Enhanced Metallopolymer Electrolytes for Wide‐Temperature Solid‐State Lithium Metal Batteries

• Published in: Angewandte Chemie Vol. 137; no. 5
• Main Authors: Zhao, Pei‐Chen, Wang, Yaoda, Huang, Qi‐Sheng, Jin, Zhong, Li, Cheng‐Hui
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley Subscription Services, Inc 27.01.2025
• Subjects: Anions; Chemical synthesis; Conductivity; Coordination; Electrochemistry; Electrolytes; Glass transition temperature; Ion currents; Lithium; Lithium batteries; Metallopolymers; Metals; Metal–organic coordination; Mo-polyoxometalates; Molten salt electrolytes; Molybdenum; Polymers; Polyoxometallates; Solid electrolytes; Solid-state Li Metal Batteries; Thermal stability; Transition temperatures
• ISSN: 0044-8249; 1521-3757
• DOI: 10.1002/ange.202416897

The practical application of polymer electrolytes is seriously hindered by the inferior Li+ ionic conductivity, low Li+ transference number (tLi+), and poor interfacial stability. Herein, a structurally novel metallopolymer is designed and synthesized by exploiting a molybdenum (Mo) paddle‐wheel complex as a tetratopic linker to bridge organic and inorganic moieties at molecular level. The prepared metallopolymer possesses combined merits of outstanding mechanical and thermal stability, as well as a low glass transition temperature (Tg <−50 °C). Based on this metallopolymer, an advanced metal–organic coordination enhanced metallopolymer electrolyte (MPE) is developed for constructing high‐performance solid‐state lithium metal batteries (LMBs). Due to the unsaturated coordination of Mo atoms, the uniformly distributed Mo‐polyoxometalates (Mo‐POMs) in metallopolymer skeleton can effectively immobilize anions (bis(fluorosulfonyl)imide anions, FSI−) and promote the dissociation of Li salts. Moreover, dynamic metal–organic coordination bonds endow the MPE with re‐processability and self‐healing, enabling it to accommodate electrode volume changes and maintain good interfacial contact. Consequently, the MPE achieves a competitive ionic conductivity of 0.712 mS cm−1 (25 °C), a high tLi+ (0.625), and a wide electrochemical stability window (>5.0 V). This study presents a unique MPE design based on metal–organic coordination enhanced strategy, providing a promising solution for developing wide‐temperature solid‐state LMBs. A structurally novel polymer crosslinked by metal–organic coordination units (defined as metallopolymer) is designed and prepared to develop high‐performance metal–organic coordination enhanced metallopolymer electrolytes (MPEs). By exploiting a Mo paddle‐wheel complex as a tetratopic linker, the organic and inorganic moieties of polymer skeleton are integrated at molecular level, without phase separation and local inhomogeneity. The coordinatively unsaturated Mo≡Mo units in Mo(II) paddle wheel complexes can serve as Lewis acid sites to effectively bind to bis(fluorosulfonyl)imide anions (FSI−), increase Li+ flux, and facilitate FSI− decomposition, resulting in uniform Li+ concentration gradients and the formation of stable fluorinated interfaces.