Boosting Low Temperature Performance of Lithium Ion Batteries at-40㧳 Using a Binary Surface Coated Li₃V₂(PO₄)₃ Cathode Material

Severe capacity degradation at low temperatures (<-20 degrees & Scy;) hampers wide applications of lithium-ion batteries (LIBs) in consumer electronics and electric vehicles. Existing works are dedicated to electrolyte modification because that electrolyte controls both Li+ transportation and interfacial reaction. However, the efforts on electrolytes are always hard to balance rate performance and low-temperature capacity due to their high viscosity. Herein, a binary coating layer for Li3V2(PO4)(3) cathode material without changing electrolyte formulation is proposed, which significantly improves the high-rate capability and low-temperature performance of batteries. YPO4 nanoparticles are in situ formed in the amorphous surface carbon layer under the reaction between Li3V2(PO4)(3) and Y(NO3)(3) during post-thermal treatment. The C+YPO4 binary coating reduces the side reactions of Li3V2(PO4)(3) at high voltage. In addition, the binary surface coating also improves the interfacial kinetics of the electrode at low temperatures. Benefiting from these advantages, the Li3V2(PO4)(3) cathode material can cycle stably at ultra-high rates up to 50 C. In addition, the capacity retention at -20 and -40 degrees & Scy; are improved to 89.1% and 75.7%, respectively. This binary surface-coated Li3V2(PO4)(3) cathode material shows promising application potential in low-temperature LIBs.