All-solid-state silicon anodes for next-generation Li-ion batteries

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The power generation and transportation sectors contribute to one third of Canada's GHG emissions. Alternative technologies such as wind energy and electric vehicles are emerging as promising solutions but require improvements to cost, performance and sustainability of key a component - rechargeable energy storage. Due to its high capacity and energy density, silicon anodes and solid-state electrolytes are promising candidates for the next-generation upgrade of the Li-ion battery. However, silicon anode performance is adversely affected by several previously insurmountable degradation mechanisms. Among these is the severe volume expansion which occurs during lithiation and leads to pulverization and loss of electrical contact within the electrode. Furthermore, when in contact with silicon, the electrolyte degrades and forms a solid electrolyte interface which slowly decomposes the electrolyte and causes the build up of electrically insulating layers between particles. To address these challenges, the University of Waterloo, in collaboration with ZEN Graphene Solutions Ltd (ZEN), proposes to develop an all-solid-state battery (SSB). The anode is composed of silicon encapsulated within ZEN's electrolyte-blocking graphene that provides void space for volume buffering. The proposed solid electrolyte will be a solid polymer electrolyte engineered with a mixed polymer matrix capable of good adhesion to the graphene and achieving high conductivity. These modifications have the potential to lead to a silicon anode with little to no degradation. When coupled to state-of-the-art Li-ion cathodes, the team expects to achieve > 320Wh/kg of total battery weight which is over a 50% improvement compared to current technology. These improvements are expected to increase the drive range and reduce the costs of electric vehicles. The improved air quality and expected reductions in GHG emissions will significantly improve the quality of life of Canadians and those disproportionately affected by climate change. The proposed built-in-Canada solution, if successful, is expected to lead to significant job growth and manufacturing capacity to create a supply chain for the growing battery market.