Lithium-ion batteries are widely used in portable electronic devices and large-scale energy storage, especially electric vehicles. However, the electrolytes used in these batteries limit their performance to a set of temperatures that are easily exceeded by winter and summer extremes in many locations. In addition, traditional electrolytes degrade battery capacity over charge/discharge cycles.

Researchers at Pacific Northwest National Laboratory have developed optimized electrolytes that greatly enhance the performance of lithium-ion batteries, particularly at low temperatures. These electrolytes contain multiple additives that improve battery operation. They enable the anode and cathode to function as efficiently as possible while preventing damage to electrodes. Possible additives include a mixture of cesium hexafluorophosphate, fluoroethylene carbonate, tris(trimethylsilyl) phosphite, and 1,3-propane sultone.

Using optimized electrolytes, lithium-ion batteries can perform well in temperatures as low as -20 degrees Celsius (4 below in Fahrenheit) and as high as 60 degrees Celsius (140 degrees Fahrenheit). In addition, the optimized electrolytes improve battery capacity retention by at least 85 percent over 1,000 charge/discharge cycles at room temperature. The approach still improves capacity retention at low and high temperatures, just by a lesser percentage. 

APPLICABILITY

PNNL’s optimized electrolytes can be used in any lithium-ion battery that needs to operate under low or high temperatures, especially batteries used in electric vehicles.