A team of researchers led by chemists at the US Department of Energy’s (DOE) Brookhaven National Laboratory has shown that using an appropriate amount of lithium difluorophosphate in a common commercial electrolyte enables stable cycling of nickel-rich layered cathode materials with an ultra-high cut-off voltage of 4.8 V. A paper on their work is published in the journal Nature Energy .
The findings offer a remedy to notorious degradation problems that crop up for nickel-rich cathode materials, especially at high voltages. This research was conducted as part of the DOE-sponsored Battery500 Consortium, which is led by DOE’s Pacific Northwest National Laboratory (PNNL) and is working to increase the energy density of lithium batteries for electric vehicles significantly.
Sha Tan, a co-first author and Ph.D. candidate at Stony Brook University conducting research with the Electrochemical Energy Storage group at Brookhaven Lab, was originally studying how an additive, lithium difluorophosphate (LiPO 2 F 2 ), could be used to improve low-temperature performance of batteries. Out of curiosity, she tried using the additive for high voltage cycling at room temperature. I found if I pushed the voltage up to 4.8 volts (V), this additive really gives great protection over the cathode and the battery achieved excellent cycling performance. Nickel-rich layered cathode materials promise high energy density for next-generation batteries when paired with lithium metal anodes. But those materials are prone to capacity loss. One of the main issues is particle cracking during high-voltage charge-discharge cycles. High voltage operation is important because the total energy […]