Regulating the Solvation Structure in Polymer Electrolytes for High‐Voltage Lithium Metal Batteries

• Published in: Angewandte Chemie International Edition Vol. 63; no. 34; pp. e202405802 - n/a
• Main Authors: Liu, Yuncong, Jin, Zhekai, Liu, Zeyu, Xu, Hao, Sun, Furong, Zhang, Xue‐Qiang, Chen, Tao, Wang, Chao
• Format: Journal Article
• Language: English
• Published: Germany Wiley Subscription Services, Inc 19.08.2024
• Edition: International ed. in English
• Subjects: Anions; Density; Dipole interactions; Electrochemistry; Electrolytes; Electrolytic cells; High voltages; High-voltage batteries; Lithium; Lithium batteries; Lithium ions; Lithium metal batteries; Metals; Molten salt electrolytes; Polymer electrolyte; Polymers; Solid electrolytes; Solvation; Solvation structures; Steric hindrance; Topology; Voltage; Polymer electrolyte; High-voltage batteries; Solvation structures; lithium metal batteries
• ISSN: 1433-7851; 1521-3773; 1521-3773
• DOI: 10.1002/anie.202405802

Solid polymer electrolytes are promising electrolytes for safe and high‐energy‐density lithium metal batteries. However, traditional ether‐based polymer electrolytes are limited by their low lithium‐ion conductivity and narrow electrochemical window because of the well‐defined and intimated Li+‐oxygen binding topologies in the solvation structure. Herein, we proposed a new strategy to reduce the Li+‐polymer interaction and strengthen the anion‐polymer interaction by combining strong Li+‐O (ether) interactions, weak Li+‐O (ester) interactions with steric hindrance in polymer electrolytes. In this way, a polymer electrolyte with a high lithium ion transference number (0.80) and anion‐rich solvation structure is obtained. This polymer electrolyte possesses a wide electrochemical window (5.5 V versus Li/Li+) and compatibility with both Li metal anode and high‐voltage NCM cathode. Li||LiNi0.5Co0.2Mn0.3O2 full cells with middle‐high active material areal loading (~7.5 mg cm−2) can stably cycle at 4.5 V. This work provides new insight into the design of polymer electrolytes for high‐energy‐density lithium metal batteries through the regulation of ion‐dipole interactions. We studied the relationship between solvation structure and ion transportation and interphase chemistry in polymer electrolytes. By combining strong Li+‐ether interactions and weak Li+‐ester interactions with steric hindrance, we get a polymer electrolyte which possesses high lithium ion transference number (0.80) and a wide electrochemical window (5.5 V versus Li/Li+). The anion‐rich solvation structure makes it be compatible with both Li metal anode and high‐voltage NCM cathode with middle‐high areal loading (~7.5 mg cm−2). Our work provides new insight into the design of high‐performance polymer electrolytes through the regulation of ion‐dipole interactions.