Si-Doped Carbon Xerogel for High Capacity Lithium and Sodium Ion Battery Anodes

Abstract

The use of dopants such as silicon, tin, and, more recently, antimony in carbonaceous anodes is a promising area of research to increase the performance of lithium and sodium ion batteries [1-3]. The biggest obstacle to the progress of this technology is the stability of these inclusions in the carbon material during charging and discharging, most notably the volume change of the active material [4-8]. An electrode design was synthesized that consists of a carbon xerogel via a sol-gel process (CX), which acts as a support structure for a dopant, silicon nanoparticles (SiNPs), and provides electronic conductivity. Syntheses have been made using poly(sodium 4-styrenesulfonate) (PSS) as a coating or binder. These syntheses showed positive results on the cyclability of the CX/SiNPs composite. A 5-fold increase was observed in the number of charge/discharge cycles before the reversible capacity was less than 80% the initial capacity when compared with a composite with no coating and conventional binder. The gradual loss in capacity in the coated composite is still unknown, but may be due to the interplay between SEI formation and the volume expansion of the SiNPs. These problems are now being addressed by various techniques to improve the chemical and mechanical stability, and tailoring the microporosity and mesoporosity to reduce the irreversibly capacity loss and increase the accessibility to the dopant material. References: [1] W. Luo et al. Journal of Power Sources 304 (2016) 340–345 [2] B. Guo et al. Journal of Power Sources 177 (2008) 205–210 [3] RSC Advances, 2012, 2, 4311–431 [4] W.J. Zhang, J. Power Sources 196 (2011) 13–24 [5] H. Wu, Y. Cui, Nano Today 7 (2012) 414–429. [6] L.Y. Beaulieu, K.W. Eberman, R.L., et al. Electrochem. Solid-State Lett. 4 (2001) A137–A140. [7] J.H. Ryu, J.W. Kim, et al. Electrochem. Solid-State Lett. 7 (2004) A306–A309. [8] M.A. Rahman, G. Song, A.I. Bhatt, et al. Adv. Funct. Mater. 26 (2016) 647–678