Rapid preparation of high electrochemical performance LiFePO4/C composite cathode material with an ultrasonic-intensified micro-impinging jetting reactor

摘要

A joint chemical reactor system referred to as an ultrasonic-intensified micro-impinging jetting reactor (UIJR), which possesses the feature of fast micro-mixing, was proposed and has been employed for rapid preparation of FePO4 particles that are amalgamated by nanoscale primary crystals. As one of the important precursors for the fabrication of lithium iron phosphate cathode, the properties of FePO4 nano particles significantly affect the performance of the lithium iron phosphate cathode. Thus, the effects of joint use of impinging stream and ultrasonic irradiation on the formation of mesoporous structure of FePO4 nano precursor particles and the electrochemical properties of amalgamated LiFePO4/C have been investigated. Additionally, the effects of the reactant concentration (C = 0.5, 1.0 and 1.5 mol L-1), and volumetric flow rate (V = 17.15, 51.44, and 85.74 mL min(-1)) on synthesis of FePO(4)(center dot)2H(2)O nucleus have been studied when the impinging jetting reactor (IJR) and UIJR are to operate in nonsubmerged mode. It was affirmed from the experiments that the FePO4 nano precursor particles prepared using UIJR have well-formed mesoporous structures with the primary crystal size of 44.6 nm, an average pore size of 15.2 nm, and a specific surface area of 134.54 m(2) g(-1) when the reactant concentration and volumetric flow rate are 1.0 mol L-1 and 85.74 mL min(-1) respectively. The amalgamated LiFePO4/C composites can deliver good electrochemical performance with discharge capacities of 156.7 mA h g(-1) at 0.1 C, and exhibit 138.0 mA h g(-1) after 100 cycles at 0.5 C, which is 95.3% of the initial discharge capacity.