Asymmetric Temperature Modulation for Extreme Fast Charging of Lithium-Ion Batteries

Adding a 200-mile range in 10 min, so-called extreme fast charging (XFC), is the key to mainstream adoption of battery electric vehicles (BEVs). Here, we present an asymmetric temperature modulation (ATM) method that, on one hand, charges a Li-ion cell at an elevated temperature of 60 degrees C to eliminate Li plating and, on the other, limits the exposure time at 60 degrees C to only similar to 10 min per cycle, or 0.1% of the lifetime of a BEV, to prevent severe solid-electrolyte-interphase growth. The asymmetric temperature between charge and discharge opens a new path to enhance kinetics and transport during charging while still achieving long life. We show that a 9.5-Ah 170-Wh/kg cell sustained 1,700 XFC cycles (6 C charge to 80% state of charge) at 20% capacity loss with the ATM, compared to 60 cycles for a control cell, and that a 209-Wh/kg BEV cell retained 91 7% capacity after 2,500 XFC cycles.