TechBlick Battery Materials Conference: Next-Gen and Beyond Lithium-Ion
By Michelle Tokarz, VP of Partnerships and Innovation, The Coretec Group
Last week, I attended the “TechBlick Battery Materials: Next-Gen and Beyond Lithium-Ion” virtual conference in order to understand current efforts to develop the kinds of lithium-ion batteries needed for electrification.
Gleb Yushin of Sila Nanotechnologies talked about the evolution of the lithium-ion battery from an initial price of $4,000 per kilowatt-hour (kWh) in 1991 to about $100/kWh today and an energy density of about 250 Watt-hours per liter (Wh/L) in 1991 to about 800 Wh/L today. It is clear that the traditional lithium-ion battery is reaching price stabilization and only minimal performance improvements are possible with existing technologies.
Current industry knowledge indicates that the full or partial replacement of traditional graphite anodes with silicon is the next technological hurdle necessary to achieve significant performance improvements in lithium-ion batteries. Several companies, including The Coretec Group, are working with silicon to increase battery performance metrics such as charging capacity, speed of charging, and battery life, such that consumers will be able to use their electric vehicles in the same way they use their gas-powered vehicles.
Coretec’s mission is engineering silicon to improve lives. Developing silicon anodes to improve the energy density (charging capacity), charging speed, and battery life of lithium-ion batteries fits well with our overall mission. We believe we have the technology, knowledge, and intellectual property to improve the performance of lithium-ion batteries for many uses.
Historically, the biggest challenge with silicon anodes has been that they swell upon charging due to the significant difference in the type of chemical bonding that occurs between silicon and lithium, as compared with what happens in traditional graphite anodes. Innovative scientists and entrepreneurs have largely solved this problem by incorporating silicon nanowires and/or intentionally introducing porosity into their anode structures, but the issue of loss of battery performance with repeated charging and discharging still remains. In fact, as much as 40% of initial charge capacity could be lost from the first to second cycle without additional design modifications, such as the transfer of active lithium to the anode material prior to the first cycle in a process known as pre-lithiation. The rapid early decrease in charge capacity is largely due to the continual formation and degradation of a solid-electrolyte-interphase (SEI) layer that is unavoidable with silicon anodes.
In fact, many of the follow-up questions at TechBlick in the presentations involving silicon anodes revolved around how to address the “SEI-layer issue.” While many companies have attempted to mitigate the cycling issues caused by this SEI layer with careful attention to the battery design criteria including material selection and cell design, most have approached the problem of the SEI layer as something “to be managed.”
In contrast, Coretec’s patent-pending methodology in silicon anodes tackles the SEI issue head-on. By intentionally creating an engineered SEI layer as part of our silicon-anode active material, we hope to make a significant contribution to current deficits in the cycling stability of silicon anodes.