EDWARD BUIEL CONSULTING LLC — Department of Energy SBIR Phase II: 13a

Description

This project focuses on the development of new lithium ion battery (LIB) electrolyte/cathode combinations that enable stabilized solid electrolyte interphases (SEI) on Si- based materials. This effort focuses on negative electrodes that include Si-based materials, where Si contributes at least 30% of the reversible capacity of the electrode. This effort will result in significantly longer cycle life and calendar life for LIBs that feature Si-containing negative electrodes. Recent work has shown that the capacity fade seen in well-designed Si and Si-based negative electrodes is a consequence of an increase in surface area with cycling as the Si-based material expands and contracts. The increased surface area results in an increase in parasitic side reactions and accelerated electrolyte consumption. High precision calorimetry combined with high precision coulometry allows an early identification of the increasing parasitic thermal power that accompanies the increasing surface area. The volume changes of Si-based materials can be diluted but they cannot be suppressed. The path forward for truly enabling Si-based materials therefore lies in targeted electrolyte chemistry. Electrolyte constituents that lead to the formation of carbon dioxide (CO2) or CO2 precursors have recently been shown to be effective in extending the cycle life of Si. It is believed the presence of CO2, or readily reducible intermediates, leads to the formation of an inorganic carbonate Si SEI and has a remarkable effect on extending cycle life. Our Phase I results show that proprietary electrolytes and cell designs developed by Coulometrics & Cyclikal increase cycle life from 500 cycles for control cells to over 900 cycles. This indicates excellent initial results and the merit of this approach to stabilize the SEI on Si-contain LIBs. Coulometrics, LLC and Cyclikal, LLC have partnered to provide an excellent balance of cell assembly and cell testing capabilities with state-of-the-art microcalorimetry. This combination has proven successful in recent years and is based on the encouraging results of our Phase I effort in which over 260 cylindrical LIBs were produced and tested in just 6 months. The combined team has excellent equipment, facilities, and 20 trained staff that have over 100 years of experience. Dr. Edward Buiel has over 25 years of experience as CTO of two advanced energy storage companies and now CEO of Coulometrics, LLC. Joe Turner has 15 years of LIB development experience and recently was R&D director of K2 Energy before joining Coulometrics. Dr. Larry Krause has over 30 years of industrial energy storage experience, especially relating to Si. The team also benefits from Coulometrics’ consulting business that has been profitable since 2008 and provides significant revenue to support this effort and any commercialization effort that may arise from this program.