Surface modification using heptafluorobutyric acid to produce highly stable Li metal anodes

Authors: Yuxiang Xie, Yixin Huang, Yinggan Zhang, Tairui Wu, Shishi Liu, Miaolan Sun, Bruce Lee, Zhen Lin, Hui Chen, Peng Dai, Zheng Huang, Jian Yang, Chenguang Shi, Deyin Wu, Ling Huang*, Yingjie Hua, Chongtai Wang* & Shigang Sun*

Abstract: The Li metal is an ideal anode material owing to its high theoretical specific capacity and low electrode potential. However, its high reactivity and dendritic growth in carbonate-based electrolytes limit its application. To address these issues, we propose a novel surface modification technique using heptafluorobutyric acid. In-situ spontaneous reaction between Li and the organic acid generates a lithiophilic interface of lithium heptafluorobutyrate for dendrite-free uniform Li deposition, which significantly improves the cycle stability (Li/Li symmetric cells >1200 h at 1.0 mA cm−2) and Coulombic efficiency (>99.3%) in conventional carbonate-based electrolytes. This lithiophilic interface also enables full batteries to achieve 83.2% capacity retention over 300 cycles under realistic testing condition. Lithium heptafluorobutyrate interface acts as an electrical bridge for uniform lithium-ion flux between Li anode and plating Li, which minimizes the occurrence of tortuous lithium dendrites and lowers interface impedance.

Link: https://www.nature.com/articles/s41467-023-38724-x