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

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 >1200h at 1.0mAcm(-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.

Automated summary

A novel surface modification technique using heptafluorobutyric acid is proposed to address the reactivity and dendritic growth issues of Li metal. The lithiophilic interface of lithium heptafluorobutyrate generated in-situ significantly improves cycle stability and Coulombic efficiency in carbonate-based electrolytes.