High-Performance Low-Temperature Li+ Intercalation in Disordered Rock-Salt Li-Cr-V Oxyfluorides

What is it about?

At -10°C and 26 mA g-1, Li2Cr0.2V0.8O2F can deliver a stable high capacity of 250 mAh g-1 (or 690 Wh kg-1) over 60 cycles. Even at -20°C and a current density of 106 mA g-1, it still delivers a steady capacity and specific energy of about 160 mAh g-1 and 400 Wh kg-1, respectively, over 100 cycles. Superior performance of Li2Cr0.2V0.8O2F over Li2VO2F and Li2CrO2F is related to its structural stability and electronic properties.

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Why is it important?

There is no noticeable increase in polarization for Li2Cr0.2V0.8O2F by reducing the operation temperature. The average discharge voltage at -20°C is about 2.46 V. Accordingly, a high specific energy of about 410 Wh kg-1 is still achievable at -20°C.