Wang Xiaohong, Li Chunhao, Liu Shiyu, Sun Yongming
Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology Wuhan 430074 China
Chem Sci. 2024 Oct 4;15(43):17979-87. doi: 10.1039/d4sc05632a.
Lithium (Li) plating, triggered by fast charging and low temperature, will cause performance degradation and safety concerns for lithium-ion batteries (LIBs). However, strategically limited and controlled Li deposition might be advantageous for enhancing energy density. The detailed mechanism and regulation for performance improvement are yet to be fully explored. This study meticulously modulates the overlithiation capacity to regulate Li plating and probes its effects on the stability of high-capacity silicon/graphite (Si/Gr) electrodes through consecutive cycling and over the calendar aging period. The Si/Gr electrode (20 wt% Si) with a 20% overlithiation degree exhibits enhanced reversible capacity in comparison to the pristine Si/Gr electrode. This improvement is attributed to precision-controlled Li deposition, the increased electrochemical utilization of Si and Gr above 0 V, and the additional intercalation/alloying reactions below 0 V, which decelerate the progression of capacity degradation and significantly boost the electrochemical performance of Si/Gr electrodes. Moreover, this tailored Si/Gr electrode with a 20% overlithiation degree attenuates the deterioration associated with calendar aging. This research not only elucidates the intricate interplay and mechanisms of Li plating on Si/Gr electrodes during overlithiation but also presents a new understanding and approach to advance the performance of LIBs and extend their service lifespan.
由快速充电和低温引发的锂（Li）金属化会导致锂离子电池（LIBs）的性能下降和安全问题。然而，策略性地限制和控制锂沉积可能有利于提高能量密度。性能改善的详细机制和调控方法尚未得到充分探索。本研究精心调节过锂化容量以调控锂金属化，并通过连续循环和长期老化来探究其对高容量硅/石墨（Si/Gr）电极稳定性的影响。与原始Si/Gr电极相比，过锂化程度为20%的Si/Gr电极（含20 wt% Si）表现出更高的可逆容量。这种改善归因于精确控制的锂沉积、高于0 V时硅和石墨电化学利用率的提高，以及低于0 V时额外的嵌入/合金化反应，这些反应减缓了容量下降的进程，并显著提升了Si/Gr电极的电化学性能。此外，这种过锂化程度为20%的定制Si/Gr电极减轻了与长期老化相关的性能劣化。本研究不仅阐明了过锂化过程中锂在Si/Gr电极上金属化的复杂相互作用和机制，还为提升锂离子电池性能和延长其使用寿命提供了新的认识和方法。
