Stable operation of highly loaded pure Si-Fe anode under ambient pressure via carboxy silane-directed robust solid electrolyte interphase

• Published in: Journal of energy chemistry 2024-07, Vol.94, p.568-576
• Main Authors: Lim, Guntae, Kang, Dong Guk, Lee, Hyeon Gyu, Tran, Yen Hai Thi, An, Kihun, Choi, Junghyun, Roh, Kwang Chul, Kim, Do Youb, Song, Seung-Wan
• Format: Article
• Language: English
• Subjects: High-energy Li-ion battery; Pure Si-Fe anode without graphite; SEI layer; Silane additive; Suppressed swelling
• ISSN: 2095-4956
• DOI: 10.1016/j.jechem.2024.02.065

Diacetoxydimethylsilane additive-derived robust solid electrolyte interphase (SEI) formed at highly loaded (3.5 mA h cm−2) pure Si-Fe anode enables suppressed swelling, prevented cell short circuit, and improved performance, from which pure Si or Si-dominant anode-based high-energy-density LIBs are anticipated. [Display omitted] Incorporation of higher content Si anode material beyond 5 wt% to Li-ion batteries (LIBs) is challenging, owing to large volume change, swelling, and solid electrolyte interphase (SEI) instability issues. Herein, a strategy of diacetoxydimethylsilane (DAMS) additive-directed SEI stabilization is proposed for a stable operation of Si-0.33FeSi2 (named as Si-Fe) anode without graphite, which provides siloxane inorganics and organics enrichment that compensate insufficient passivation of fluoroethylene carbonate (FEC) additive and reduce a dependence on FEC. Unprecedented stable cycling performance of highly loaded (3.5 mA h cm−2) pure Si-Fe anode is achieved with 2 wt% DAMS combined with 9 wt% FEC additives under ambient pressure, yielding high capacity 1270 mA h g−1 at 0.5 C and significantly improved capacity retention of 81% after 100 cycles, whereas short circuit and rapid capacity fade occur with FEC only additive. DAMS-directed robust SEI layer dramatically suppresses swelling and particles crossover through separator, and therefore prevents short circuit, demonstrating a possible operation of pure Si or Si-dominant anodes in the next-generation high-energy-density and safe LIBs.