Hybrid covalent organic-framework-based electrolytes for optimizing interface resistance in solid-state lithium-ion batteries
Dongming Cheng, Cui Sun, Zhongling Lang, Jinhua Zhang, Ajuan Hu, Jianing Duan, Xinyu Chen, Hong‐Ying Zang, Jiajia Chen, Mingsen Zheng, Quanfeng Dong
Abstract
High ion conductivity and low electrode-electrolyte interface resistance are intensively pursued topics for the development of solid-state Li-ion batteries with high safety and energy density. Here, we propose a design using keto-enamine covalent organic frameworks (TPBD) and polyethylene oxide (PEO) to prepare a solid-state electrolyte (TPBD-LiPF6@PEO), achieving a high ion conductivity of 0.543 mS cm−1 at 25°C and optimizing the electrode-electrolyte interface resistance in Li-ion batteries. Solid-state nuclear magnetic resonance experiments and density functional theory calculations show that the strong interaction between the –C=O site in TPBD and Li+ ions promotes the dissociation of LiPF6. The assembled LiFePO4|TPBD-LiPF6@PEO|Li batteries without using liquid electrolytes offer a specific capacity of nearly 140 mAh g−1 at 0.2 C with a columbic efficiency of 99.6% after 200 cycles at 25°C. This strategy for preparing solid-state electrolytes provides practical ideas and suggestions in the development of solid-state energy devices.