Anion‐modulated Ion Conductor with Chain Conformational Transformation for stabilizing Interfacial Phase of High‐Voltage Lithium Metal Batteries

• Published in: Angewandte Chemie International Edition 2024-05, Vol.63 (19), p.e202317856-n/a
• Main Authors: Wang, Chao, Zhao, Xiaoxue, Li, Dabing, Yan, Chong, Zhang, Qiang, Fan, Li‐Zhen
• Format: Article
• Language: English
• Subjects: Anions; Chains (polymeric); Charge transport; Conductors; Conformation; Electrodes; Electrolytes; High voltages; Interface Phase; Interface stability; Interfacial Chemistry; Ion charge; Ion transport; Lithium; Lithium batteries; Molecular conformation; Polymers; Polyvinyl chloride; Polyvinylene carbonates; Solid Polymer Electrolyte; Solid-State Lithium Metal Batteries; Solvation; Voltage
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.202317856

In solid‐state lithium metal batteries (SSLMBs), the inhomogeneous electrolyte‐electrode interphase layer aggravates the interfacial stability, leading to discontinuous interfacial ion/charge transport and continuous degradation of the electrolyte. Herein, we constructed an anion‐modulated ionic conductor (AMIC) that enables in situ construction of electrolyte/electrode interphases for high‐voltage SSLMBs by exploiting conformational transitions under multiple interactions between polymer and lithium salt anions. Anions modulate the decomposition behavior of supramolecular poly (vinylene carbonate) (PVC) at the electrode interface by changing the spatial conformation of the polymer chains, which further enhances ion transport and stabilizes the interfacial morphology. In addition, the AMIC weakens the “Li+‐solvation” and increases Li+ vehicle sites, thereby enhancing the lithium‐ion transport number (tLi+=~0.67). Consequently, Li || LiNi0.8Co0.1Mn0.1O2 cell maintains about 85 % capacity retention and Coulombic efficiency >99.8 % in 200 cycles at a charge cut‐off voltage of 4.5 V. This study provides a new understanding of lithium salt anions regulating polymer chain segment behavior in the solid‐state polymer electrolyte (SPE) and highlights the importance of the ion environment in the construction of interfacial phases and ionic conduction. A functional polymer electrolyte for high‐voltage lithium‐metal batteries was constructed by modulating the behavior of supramolecular poly (vinylene carbonate) from linear to low entropy globular conformation driven by a multi‐ion environment and achieving the maximum compatibility of the polymer solid electrolyte in situ‐derived poly(carbonate) anionic coating with the electrodes. This work emphasizes the importance of modulating the polymer chain segment conformation for the in situ construction of the solid‐state electrolyte interphase.