Author :
Zhang, Bao ; Zhang, Jiafeng ; Shen, Chao ; Peng, Chunli ; Lian, Qian
Abstract :
FePO4·2H2O precursor was synthesized from FePO4·7H2O, NH4H2PO4, NH3·H2O and H2O2 as the oxidizing agent by solution precipitation route. Effects of reaction conditions, such as solution concentration, reaction temperature, stirring speed, adding amount of H2O2, pH and drying time on synthesis of FePO4·2H2O precursor were studied. Afterwards, Li2CO3, FePO4·2H2O and glucose were ground by wet process and dried fully. And then, LiFePO4 was prepared by carbothermal reduction. The phases, structure and morphology of FePO4·2H2O and LiFePO4 were characterized by ICP, TG-DSC, XRD and SEM. Effects of reaction conditions on electrochemical performance of LiFePO4 were explored. The results show that no impurities exist in the FePO4·2H2O when reaction temperature is 80°C, stirring speed is 800r/min, adding amount of H2O2 is 3mL, pH is 2, drying time is 12h and reactant concentration is from 0.1mol/L to 1.5mol/L. However, production rate of FePO4·2H2O is no more than 100% when pH is below 2 with either reactant concentration. LiFePO4 made from FePO4·2H2O precursor synthesized under the condition that pH is 2 and reactant concentration is 1mol/L shows excellent electrochemical performance. It has an initial discharge capacity of 154.4mAh/g at 0.1C.
Keywords :
X-ray diffraction; differential scanning calorimetry; discharges (electric); drying; electrochemistry; iron compounds; lithium compounds; oxidation; pH; precipitation; scanning electron microscopy; FePO4-H2O; ICP; LiFePO4; SEM; TG-DSC; XRD; carbothermal reduction; discharge capacity; drying time; electrochemical performance; glucose; oxidizing agent; pH; reactant concentration; reaction conditions; reaction temperature; solution concentration; solution precipitation route; stirring speed; temperature 80 degC; time 12 h; wet process; Batteries; Cathodes; Chaos; Energy consumption; Iron; Lithium; Production; Solid state circuits; Temperature; Thermal pollution;
