Carbothermal reduction of LiFePO4/C composite cathodes using acid-washed iron red as raw material through carboxylic acid pyrolysis reducing gas participation strategies

The study on the gas production behavior and pyrolysis kinetics of citric acid and tartaric acid provides a new idea for the researchers to choose a certain carboxylic acid. The results of TG-FTIR, TG-MS and kinetics research show that, compared with tartaric acid, the activation energy required for citric acid pyrolysis is lower, and more reducing gas (CO) can be produced, which is more suitable for use as a reducing agent. Therefore, we used citric acid, acid-washed iron red, Li2CO3 and NH4H2PO4 as raw materials to synthesize LiFePO4/C cathode materials by carbothermal reduction method. Through XRD, SEM and electrochemical measurements, it was found that the optimal calcination temperature of LiFePO4/C synthesis was 650 °C, the optimal mass ratio of citric acid to pickling iron red was 0.4:1, and the discharge capacity of the first cycle of the sample reached 120 mAh g−1 at 0.1 C, after 50 cycles, the discharge capacity of 122 mAh g−1 remained. This fundamental study provides a basic insight about the citric acid and tartaric acid pyrolysis, which is a new idea to supplement the evidence for the choice and application of carboxylic acid about reduce reaction.