Lee Jun-Hyeong, Lee Hajin, Lee Jaewoo, Kang Tae Woog, Park Jung Hyun, Shin Jae-Hoon, Lee Hyunji, Majhi Dibyananda, Lee Sang Uck, Kim Jong-Ho
Department of Materials Science and Chemical Engineering, Hanyang University, Ansan, 15588, Republic of Korea.
School of Chemical Engineering, Sungkyunkwan University, Suwon 16149, Republic of Korea.
ACS Nano. 2023 Sep 12;17(17):17372-17382. doi: 10.1021/acsnano.3c05405. Epub 2023 Aug 25.
Organic solid electrolytes compatible with all-solid-state Li metal batteries (LMBs) are essential to ensuring battery safety, high energy density, and long-term cycling performance. However, it remains a challenge to develop an approach to provide organic solid electrolytes with capabilities for the facile dissociation of strong Li-ion pairs and fast transport of ionic components. Herein, a diethylene glycol-modified pyridinium covalent organic framework (DEG-PMCOF) with a well-defined periodic structure is prepared as a multicomponent solid electrolyte with a cationic moiety of high polarity, an additional flexible ion-transporter, and an ordered ionic channel for all-solid-state LMBs. The DEG-containing pyridinium groups of DEG-PMCOF allow a lower dissociation energy of Li salts and a smaller energy barrier of Li-ion transport, leading to high ion conductivity (1.71 × 10 S cm) and a large Li-ion transfer number (0.61) at room temperature in the solid electrolyte. The DEG-PMCOF solid electrolyte exhibits a wide electrochemical stability window and effectively suppresses the formation of Li dendrites and dead Li in all-solid-state LMBs. Molecular dynamics and density functional theory simulations provide insights into the mechanisms for the enhanced Li-ion transport driven by the integrated diffusion process based on hopping motion, vehicle motion, and free diffusion of DEG-PMCOF. The all-solid-state LMB assembled with a DEG-PMCOF solid electrolyte displays a high specific capacity with a retention of 99% and an outstanding Coulombic efficiency of 99% at various C-rates during long-term cycling. This DEG-PMCOF approach can offer an effective route to design various solid-state Li batteries.
与全固态锂金属电池（LMBs）兼容的有机固体电解质对于确保电池安全、高能量密度和长期循环性能至关重要。然而，开发一种方法来赋予有机固体电解质轻松解离强锂离子对和快速传输离子成分的能力仍然是一个挑战。在此，制备了一种具有明确周期性结构的二甘醇改性吡啶共价有机框架（DEG-PMCOF），作为一种多组分固体电解质，用于全固态LMBs，它具有高极性阳离子部分、额外的柔性离子传输体和有序离子通道。DEG-PMCOF中含DEG的吡啶基团使锂盐的解离能更低，锂离子传输的能垒更小，从而在室温下的固体电解质中具有高离子电导率（1.71×10 S cm）和大锂离子迁移数（0.61）。DEG-PMCOF固体电解质表现出宽的电化学稳定性窗口，并有效抑制全固态LMBs中锂枝晶和死锂的形成。分子动力学和密度泛函理论模拟深入了解了基于DEG-PMCOF的跳跃运动、载体运动和自由扩散的集成扩散过程驱动的锂离子传输增强机制。用DEG-PMCOF固体电解质组装的全固态LMB在长期循环过程中的各种C倍率下显示出高比容量，保留率为99%，库仑效率高达99%。这种DEG-PMCOF方法可以为设计各种固态锂电池提供一条有效途径。
