Low Impedance Cells with Garnet-Based Solid-State Electrolytes

Performance of cells with a garnet electrolyte at high rates and at low temperatures is of critical importance to deployment of solid-state cells in electric vehicles (EV). Achieving EV-relevant performance requires improvements in cell impedance across multiple components of the cell, including the catholyte and solid-state electrolyte. Realizing low temperature capable catholytes and other low impedance cell designs for hybrid solid-state cells is essential for deployment in EV applications so that solid-state cells may remain fast-charging and long lasting even in adverse conditions. To maximize cell performance and energy density, ION is developing a hybrid cell which is based upon a garnet-type solid state electrolyte formed into a bilayer structure which enables no applied pressure or cell heating for cell operation (a critical factor for ease of integration into EV battery packs). The bilayer is composed of a dense layer that acts as a separator and a porous layer that acts as a host structure for an energy-dense lithium metal anode. In Phase I, ION achieved significant progress towards demonstrating a garnet compatible catholyte capable of meeting USABCĺs targets for low-temperature conditioning and solidified commercial relationships with catholyte suppliers who will remain critical partners for future development and commercial catholyte supply. A major outcome of Phase I was the discovery of a drop-in alternative catholyte that returned an 8-fold increase in capacity when cycled at C/3 and -15 °C compared to IONĺs baseline formulation, with full capacity recovery when cells were heated back up to room temperature. The proposed Phase II project will aim to scale these improvements and reduce impedance across other critical cell components in larger cell formats. With the technologyĺs potential demonstrated in a proof-of- concept cell, successful catholyte formulations from Phase I will be further evaluated for commercial readiness and accompanying cell designs will be optimized to achieve necessary performance metrics for EV as defined by USABC. The project will also leverage IONĺs recently installed pilot line to assemble high-capacity cells to demonstrate these performance improvements. Tech to market activities will involve further developing commercial relationships with strong industrial partners who manufacture electrolyte substituents from R&D- to Gigafactory-level scales. This approach is critical to technology deployment because there is a direct path to scale-up supply and setting of cost targets necessary for EV deployment which will be a focus of the project if carried into Phase III. Further success in developing a low-temperature capable catholyte and other low impedance designs for solid-state applications in Phase II will directly impact the extent to which the rate and total deployment of EV cells is achieved. Future Phase III projects will lead to further optimization, scaling, and commercialization of the catholyte formulation for many cell applications. Several groups would benefit from the development and access to this type of catholyte and other novel designs. This technology will lend itself to additional development from cell makers or licensees, lowered cell costs for automotive OEMs building U.S. factories, increased manufacturing jobs for the American public, and improved supply chain security.