Sustainable SiC Composite Anodes, Graphite Accelerated Lithium Storage

Abstract

Realizing more holistic electrification in society to disengage current dependence on nonrenewable fuels requires balancing between energy storage mechanisms and actual environmental benefits gained from the transition from traditional resources. Given that the majority of greenhouse gas emissions in battery value chains originate from material mining and production, silicon carbide (SiC) derived from the agricultural waste, rice hull ash (RHA), is introduced as an environmentally-benign alternative anode material. 
SiC with hard carbon (SiC/HC) exhibits capacity increases on long-term cycling, reaching capacities of >950 mAh g-1 competitive with elemental Si with complementary porous spaces. Herein, a relatively low amount (< 30 wt. %) of graphite added to SiC/HC composites greatly promotes capacity increases while retaining sustainability. Comparison between graphite contents found the optimized 30 wt. % graphite (SiC/HC/30G) boosted performance, doubling capacity increasing rate and subsequently saving >70 % time to reach target specific capacities at C/10. At 2C, SiC/HC/30G offers enhanced specific capacities at ≈220 mAh g-1. The positive effects from the coincidentally formed HC are demonstrated by oxidizing HC to form SiC/O, followed by graphite addition. Experimental post-mortem analyses support that SiC/graphite composites provide a promising solution for implementing agricultural waste-derived material for next-generation lithium storage.