清华大学张强团队报道了安全锂离子电池石墨电极的镀锂界限。 相关研究成果发表在2021年4月1日出版的《德国应用化学》。

石墨一直是实用锂离子电池的主要阳极材料。然而，石墨电极中不受控制的锂离子镀层仍然是危及电池寿命和安全的主要瓶颈，这促使人们为消除锂离子镀层做出了巨大的努力。

该文系统地研究了安全锂离子电池用石墨电极的镀锂界限。一方面，通过确定石墨阳极中均匀镀锂的持久量，该电池的安全性能优于枝晶锂电池。

另一方面，由于锂镀层的均匀分布，可以消除“死锂”的存在，并且在可逆电镀/剥离过程中沉积的锂的平均库仑效率可高达99.5%。由于LiNi0.5Mn0.3Co0.2O2 |石墨电池镀锂量有限，库仑效率高，500次循环后容量保持率高达80.2%。

该研究工作为进一步提高锂离子电池的快速充电能力、低温性能和能量密度提供了新的思路。

附：英文原文

Title: The Boundary of Lithium Plating in Graphite Electrode for Safe Lithium‐Ion Batteries

Author: Wenlong Cai, Chong Yan, Yu-Xing Yao, Lei Xu, Xiao-Ru Chen, Jia-Qi Huang, Qiang Zhang

Issue&Volume: 2021-04-01

Abstract: Graphite has been the dominant anode material for practical lithium‐ion batteries. However, uncontrolled Li plating in graphite electrodes remains the main bottleneck that endangers battery life and safety, which have driven tremendous efforts aiming to eliminate Li plating. Herein we systematically investigate the boundary of Li plating in graphite electrodes for safe lithium‐ion batteries. On one hand, the cell exhibits superior safety performance than that with Li dendrites by defining the endurable amount of uniform Li plating in graphite anode. On the other hand, the presence of “dead Li” can be eliminated owing to the uniform distribution of Li plating, and the average Coulombic efficiency for deposited Li during the reversible plating/stripping process is decoupled as high as ~99.5%. Attributing to the limited Li plating with superior Coulombic efficiency, the LiNi0.5Mn0.3Co0.2O2 | graphite cell achieves a high capacity retention of 80.2% over 500 cycles. This work sheds a different light on further improving the fast‐charging capability, low‐temperature performance, and energy density of practical lithium‐ion batteries.

DOI: 10.1002/anie.202102593

Source: https://onlinelibrary.wiley.com/doi/10.1002/anie.202102593