High tap-density and high performance LiFePO4/C cathode material synthesized by the combined sol spray-drying and liquid nitrogen quenching method

Abstract The cathode material LiFePO 4 /C is synthesized by a combined sol spray-drying and liquid nitrogen quenching method. Combining the advantages of sol–gel, spray-drying, and quenching, the well crystallized LiFePO 4 /C sample possesses both high tap-density and excellent electrochemical performance. The sphere-like particles are of the size 0.1–6 μm, and the tap-density is as high as 1.53 g cm −3 . TEM results show that there are a number of defects in LiFePO 4 crystals, and a uniform carbon layer (∼2 nm) exists on the LiFePO 4 grain surface. Electrochemical tests reveal that quenching can greatly improve the rate capability and cycle performance of LiFePO 4 /C. The quenched sample shows the initial discharge capacities of 162.5, 154.7 and 117.8 mA h g −1 at 0.1 C , 1 C and 10 C rate, respectively, and after the cell cycled 110 times at different rates, the capacity can recover to 99.4% of its original value when the rate reverses back to 0.1 C .