Moharana Sanghamitra, West Geoff, Walker Marc, Yan Xinjie S, Loveridge Melanie
Warwick Manufacturing Group (WMG), University of Warwick, Coventry CV4 7AL, U.K.
Department of Physics, University of Warwick, Coventry CV4 7AL, U.K.
ACS Appl Mater Interfaces. 2022 Sep 21;14(37):42078-42092. doi: 10.1021/acsami.2c11175. Epub 2022 Sep 12.
Fast charging promotes Li dendrite formation and its growth on graphite anodes, which affects cell performance in Li-ion batteries (LIBs). This work reports the formation of a robust SEI layer by introducing a KPF inorganic additive into the electrolyte. An optimal concentration of 0.001 M KPF effectively inhibits the growth of Li dendrites at 2C charging rates, compared with a commercial electrolyte. Electrolytes containing a KPF additive are shown here to deliver dual effects to mitigate the growth of dendrites. A thin LiF-rich SEI layer is formed on graphite, which blocks the electron leakage pathways. Additionally, K resides at defect sites (such as particle boundaries) due to its faster diffusion rate and blocks the incoming Li and restricts the growth of Li dendrites. The electrolyte with optimum concentration of KPF, i.e., 0.001 M, effectively directs Li transport through the thin, durable, and low resistance LiF-rich SEI layer. This has implications for fast charging through optimization of the electrode/electrolyte interphase by controlling additive concentrations.
快速充电会促进锂枝晶在石墨阳极上的形成及其生长，这会影响锂离子电池（LIBs）的电池性能。这项工作报道了通过在电解质中引入KPF无机添加剂形成坚固的固体电解质界面（SEI）层。与商业电解质相比，0.001 M的最佳KPF浓度在2C充电速率下能有效抑制锂枝晶的生长。此处显示含有KPF添加剂的电解质具有减轻枝晶生长的双重作用。在石墨上形成了一层富含LiF的薄SEI层，它阻断了电子泄漏路径。此外，由于K的扩散速率更快，它会驻留在缺陷部位（如颗粒边界），阻挡进入的Li并限制锂枝晶的生长。具有最佳KPF浓度（即0.001 M）的电解质有效地引导Li通过薄的、耐用的且低电阻的富含LiF的SEI层进行传输。这对于通过控制添加剂浓度优化电极/电解质界面来实现快速充电具有重要意义。
