Lithium Iron Phosphate Superbattery for Mass-Market Electric Vehicles

Narrow operating temperature range and low charge rates are two obstacles limiting LiFePO4-based batteries as superb batteries for mass-market electric vehicles. Here, we experimentally demonstrate that a 168.4 Wh/kg LiFePO4/graphite cell can operate in a broad temperature range through self-heating cell design and using electrolytes containing LiFSI. Remarkable high-temperature stability with 6100 h of cycle life was achieved at 60 degrees C. With self-heating, the cell can deliver an energy and power density of 90.2 Wh/kg and 1227 W/kg, respectively, even at an ultralow temperature of -50 degrees C, compared to almost no performance for cells without self-heating. The heating process took 164 s and only 0.161% of the cell energy per degree of temperature rise. Fast charging at a 6C rate was achieved at all ambient temperatures. The total preheating and charging time was less than 12 min, and the cell finished 2500 cycles of 6C charging while still retaining 81.3% capacity.