XFC R&D: MSMD Modeling & Thermal Testing

A 2017 DOE technology gap assessment report [1] established goals for next-generation electric vehicle (EV) batteries, namely battery cost of $80/kWh, energy density of 275 Wh/kg and 550 Wh/L, vehicle range of 300 miles, and charge time of 80% ?SOC in 15 minutes. Compared to thin electrodes, thick electrodes are preferred due to less inert material, higher energy density and lower cost. Unfortunately, today’s thick electrodes cannot tolerate fast charge rates. The thick electrodes have increased distance for ionic transport through the liquid electrolyte. Thin electrode batteries are capable of fast charge, however they come at an almost 2x increase in cell cost (from $103/kWh to $196/kWh) and have around 20% less energy density (180Wh/kg vs. 220 Wh/kg) [1]. In addition to polarization and low capacity, electrolyte transport limitations can lead to lithium plating, a side reaction with degradation and safety consequences. It is uncertain what graphite materials can best tolerate fast charge and why. At the system level, fast charging presents thermal management challenges to remove the heat generated during charging.