Kang Shinuo, Lou Xiaobing, Shen Ming, Geng Fushan, Hu Bingwen
Shanghai Key Laboratory of Magnetic Resonance, School of Physics and Electronic Science, East China Normal University, Shanghai 200062, P. R. China.
J Phys Chem Lett. 2024 Dec 19;15(50):12248-12256. doi: 10.1021/acs.jpclett.4c03022. Epub 2024 Dec 5.
Metallic lithium deposition processes in NCM811∥graphite full cells during extreme-fast charging of 4 C (fully charged within 15 min) are detected via electron paramagnetic resonance (EPR) and EPR imaging over hundreds of cycles to quantify lithium deposits and visualize their spatial distribution. EPR imaging shows that constant-voltage charge generates loose Li dendrites with divergent growth whereas overcharge leads to long dendrites with vertical growth, and these Li deposits accumulate at the anode edges, which could deplete the Li resource at the cathode edges. Moreover, quantitative EPR indicates that the stripping current correlates to the deposit surface areas, while the reintercalation current depends on the contact areas between plated Li and graphite. Overall, the results of EPR and EPR imaging suggest that the introduction of a relaxation period after extreme-fast charge for Li reintercalation into graphite is important to mitigate the accumulation of dead Li.
通过电子顺磁共振（EPR）和EPR成像在数百个循环中检测了NCM811∥石墨全电池在4 C极端快速充电（15分钟内充满电）过程中的金属锂沉积过程，以量化锂沉积物并可视化其空间分布。EPR成像表明，恒压充电会产生生长方向发散的松散锂枝晶，而过充电会导致垂直生长的长枝晶，并且这些锂沉积物在阳极边缘积累，这可能会耗尽阴极边缘的锂资源。此外，定量EPR表明，脱嵌电流与沉积物表面积相关，而再嵌入电流取决于镀锂与石墨之间的接触面积。总体而言，EPR和EPR成像结果表明，在极端快速充电后引入一个锂重新嵌入石墨的弛豫期对于减轻死锂的积累很重要。
