DESC0025183

For this SBIR Phase I project, the applicant will develop an advanced sodium-ion battery with high energy density for electric vehicle applications. Current state-of-the-art lithium-ion batteries have good performance but remain too costly and too prone to fires for widespread, mass-market adoption for electric vehicles. In recent years, lithium-ion batteries using a lithium iron phosphate cathode have emerged as the dominant technology for electric vehicles. While they offer lower cost, improved safety and excellent cyclability, their energy density is limited and cost needs to further come down for electric vehicles to be widely adopted. To this end, sodium-ion batteries are generally regarded as the next technology on the horizon. In this context, the applicant aims at developing an advanced sodium-ion battery. While conventional sodium-ion has lower energy density than lithium iron phosphate, the applicantĺs proposed sodium-ion battery directly addresses the energy density shortcoming (by using a combination of a tin-based anode and a layered oxide cathode), and further reduces cost by avoiding the use of lithium (instead using abundant sodium) and copper (instead using aluminum). This results in the advanced sodium-ion chemistry having a cell-level cost of $65/kWh at scale compared to the $90/kWh of lithium-ion iron phosphate. In addition, it has improved safety (it can be safely transported at 0 V), has superior energy density (>400 Wh/L) compared to lithium iron phosphate (300-350 Wh/L) with a similar form factor (18650 cylindrical), and can operate over a wider temperature range (-40 to 60°C). A schematic of a conventional sodium-ion battery and the advanced sodium-ion battery is provided below in Figure 1. Figure 1. Schematic of a conventional sodium-ion battery (left) and the advanced tin-based sodium-ion battery (center). Right: Prototype, first-generation sodium-ion 18650 cylindrical cells produced by the applicant. During Phase I, the applicant will (1) develop the new, advanced sodium-ion cell chemistry, (2) conduct cell optimization, and (3) scale up the chemistry to the cylindrical form factor with a minimum capacity of 1Ah. Cylindrical cells are a commonly used form factor for electric vehicles, and this project will thus serve as a vital feasibility study and development milestone for future scaling efforts and eventual deployment. Commercial Applications and Other Benefits: Provided that the project milestones are hit and the 1Ah cylindrical cell is demonstrated (produced using the exact same manufacturing processes as lithium-ion without any new or custom equipment), this will de-risk the technology and pave the way for future commercialization of the advanced sodium-ion technology. The battery makes up approximately 40% of the cost of an electric vehicle, so the cost to produce the electric vehicle can be brought down dramatically with the advent of this new, safer, high-performance technology.