Inhibition of silicon-based anode interfacial volume expansion behavior by 1,3,6-hexane trinitrile additive via induced interfacial solvation effect

• Published in: Journal of power sources 2024-09, Vol.613, p.234922, Article 234922
• Main Authors: Li, Chunlei, Zong, Feifei, Huang, Jin, Wang, Jie, Sun, Jinlong, Dong, Hong, Song, Linhu, Zhu, Yu, Li, Shiyou, Cui, Xiaoling, Zhang, Ningshuang
• Format: Article
• Language: English
• Subjects: 1,3,6-Hexane trinitrile; Lithium-ion battery; Silicon-based anode; Solvation structure; Volume expansion
• ISSN: 0378-7753
• DOI: 10.1016/j.jpowsour.2024.234922

Silicon(Si)-based anodes exhibit higher energy density than traditional graphite anodes but suffer from significant volume changes during lithiation/delithiation, destabilizing the solid electrolyte interface (SEI) and reducing cycle stability. This study explores the effect of 1,3,6-hexane trinitrile (HTCN) on mitigating Si@C electrode expansion. The inclusion of HTCN modifies the original solvation structure of Li+, and the HTCN additive undergoes preferential coordination with Li+ because its binding energy with Li+ is larger than that of ethylene carbonate (EC). This lowers the lowest unoccupied molecular orbital (LUMO) of the HTCN-containing solvation structure, promoting preferential reduction decomposition on the anode surface. This process increases inorganic Li3N formation and produces a rich carbon-organic SEI film, effectively reducing electrolyte decomposition and Si@C anode expansion from 72.98 % to 4.46 %. Adding 1 % HTCN to Si@C/Li half-cells enhances capacity retention to 72.4 % after 100 cycles at 0.2C, significantly outperforming cells without HTCN (50.9 %). This study provides a new idea for constructing high-performance SEI films to inhibit electrode expansion by adjusting the solvation structure of Li+. •HTCN preferentially coordinates with Li+, altering the solvation structure.•The STD+1 % HTCN electrolyte preferentially reduces to form Li(PF6)1(HTCN)3.•1 % HTCN addition boosts SEI's inorganic Li3N, enhancing Li+ diffusion regulation.•HTCN boosts carbon-rich components, reducing expansion and interfacial cracking.