Journal of Energy Chemistry ›› 2023, Vol. 79 ›› Issue (4): 340-347.DOI: 10.1016/j.jechem.2022.12.058

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Tuning desolvation kinetics of in-situ weakly solvating polyacetal electrolytes for dendrite-free lithium metal batteries

Peng Wena,b, Yimin Liua, Jinyan Maoa, Xiaotong Liua, Weiping Lia, Yang Rena, Yang Zhoub, Fei Shaoa, Mao Chenb, Jun Lina, Xinrong Lina,*   

  1. aKey Laboratory of Medicinal Chemistry for Natural Resource, Ministry of Education and Yunnan Province, School of Chemical Science and Technology, Yunnan University,Kunming 650091, Yunnan, China;
    bState Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science, Fudan University, Shanghai 200433, China
  • Received:2022-10-09 Revised:2022-12-28 Accepted:2022-12-28 Online:2023-04-15 Published:2023-05-30
  • Contact: * E-mail address: xrlin@ynu.edu.cn (X. Lin).

Abstract: The host structure of polymers significantly influences ion transport and interfacial stability of elec-trolytes, dictating battery cycle life and safety for solid-state lithium metal batteries. Despite promising properties of ethylene oxide-based electrolytes, their typical clamp-like coordination geometry leads to crowd solvation sheath and overly strong interactions between Li+ and electrolytes, rendering difficult dissociation of Li+ and unfavorable solid electrolyte interface (SEI). Herein, we explore weakly solvating characteristics of polyacetal electrolytes owing to their alternately changing intervals between -O- coor-dinating sites in the main chain. Such structural asymmetry leads to unique distorted helical solvation sheath, and can effectively reduce Li+-electrolyte binding and tune Li+ desolvation kinetics in the in-situ formed polymer electrolytes, yielding anion-derived SEI and dendrite-free Li electrodeposition. Combining with photoinitiated cationic ring-opening polymerization, polyacetal electrolytes can be instantly formed within 5 min at the surface of electrode, with high segmental chain motion and well adapted interfaces. Such in-situ polyacetal electrolytes enabled more than 1300-h of stable lithium elec-trodeposition and prolonged cyclability over 200 cycles in solid-state batteries at ambient temperatures, demonstrating the vital role of molecular structure in changing solvating behavior and Li deposition sta-bility for high-performance electrolytes.

Key words: Polymer electrolyte, In-situ photoinitiated polymerization, Weakly solvating effect, Polyacetal, Lithium electrodeposition