Li Weiping, Han Shantao, Xiao Chenxi, Yan Jingying, Wu Baifei, Wen Peng, Lin Jun, Chen Mao, Lin Xinrong
Department Division of Natural and Applied Sciences, Duke Kunshan University, Kunshan, Jiangsu, 215306, China.
School of Chemical Science and Technology, Yunnan University, Kunming, 650091, China.
Angew Chem Int Ed Engl. 2024 Oct 14;63(42):e202410392. doi: 10.1002/anie.202410392. Epub 2024 Sep 13.
The poor electrochemical stability window and low ionic conductivity in solid-state electrolytes hinder the development of safe, high-voltage, and energy-dense lithium metal batteries. Herein, taking advantage of the unique electronic effect of nitrile groups, we designed a novel azanide-based single-ion covalent organic framework (CN-iCOF) structure that possesses effective Li transport and high-voltage stability in lithium metal batteries. Density functional theory (DFT) calculations and molecular dynamics (MD) revealed that electron-withdrawing nitrile groups not only resulted in an ultralow HOMO energy orbital but also enhanced Li dissociation through charge delocalization, leading to a high t of 0.93 and remarkable oxidative stability up to 5.6 V (vs. Li/Li) simultaneously. Moreover, cyanation leveraging Strecker reaction transformed reversible imine-linkage to a stable sp-carbon-containing azanide anion, which facilitated contorted alignment of transport "ladders" along the one-dimensional anionic channels and the ionic conductivity could reach 1.33×10 S cm at ambient temperature without any additives. As a result, CN-iCOF allowed operation of solid-state lithium metal batteries with high-voltage cathodes such as LiNiMnCoO (NCM811), demonstrating stable lithium deposition up to 1,100 h and reversible battery cycling at ambient temperature up to 4.5 V, shedding light on the importance of discovering new functionality for forthcoming high-performance batteries.
固态电解质中较差的电化学稳定性窗口和较低的离子电导率阻碍了安全、高压和高能量密度锂金属电池的发展。在此，利用腈基独特的电子效应，我们设计了一种新型的基于氮化物的单离子共价有机框架（CN-iCOF）结构，该结构在锂金属电池中具有有效的锂传输和高压稳定性。密度泛函理论（DFT）计算和分子动力学（MD）表明，吸电子腈基不仅导致超低的HOMO能量轨道，还通过电荷离域增强了锂的解离，从而同时导致高达0.93的高迁移数t和高达5.6 V（相对于Li/Li）的显著氧化稳定性。此外，利用斯特雷克反应进行氰化将可逆的亚胺键转化为稳定的含sp碳的氮化物阴离子，这促进了传输“梯子”沿一维阴离子通道的扭曲排列，并且在不添加任何添加剂的情况下，离子电导率在室温下可达到1.33×10 S cm。结果，CN-iCOF允许使用诸如LiNiMnCoO（NCM811）等高电压阴极的固态锂金属电池运行，在室温下展示了长达1100小时的稳定锂沉积和高达4.5 V的可逆电池循环，为即将到来的高性能电池发现新功能的重要性提供了线索。
