A facile synthesis route has been developed to prepare LiFePO 4 /C composites by using Fe−P waste slag from the industrial production of yellow phosphorus. The processes included reclaiming Fe and P in the form of a ferroalloy, preheating the Fe−P with lithium salts, and complementary phosphorus source in air to produce a precursor, and calcining the precursor with glucose in Ar to obtain the products. The reaction process and electrochemical performance were investigated with various techniques. LiFePO 4 /C with 5.9 wt % carbon exhibits enhanced power capability, low polarization, high reaction activity and reversibility. The discharge capacities are 150, 147, 131, 124, 112, and 93 mAh/g at different current rates of 0.1, 0.2, 0.5, 1, 2, and 5 C, respectively. The recovery rate at 0.1 C is 98.9% after 130 cycles at the given rates. The results are comparable to that of the LiFePO 4 /C prepared using FePO 4 or other Fe salts, which indicates the applicability of the novel simple way put forward in this work to convert industrial waste into energy materials for scaling up based on low cost.

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The electrolyte, a key component for the successful operation of energy materials, is greatly affected by its solvents. The influence of solvents on the electrochemical performance of a LiFePO4/C composite cathode was investigated at various operating temperatures. The reaction kinetics of the LiFePO4/C composite electrode, including changes of rate capability, redox potential, polarization degree, electrode reaction process, exchange current densities, and activation energies, were evaluated using various techniques. The composition and volume ratio of solvents greatly affect the electrode kinetics. In the mixed solvents of ethylene carbonate (EC), dimethyl carbonate (DMC) and ethyl methyl carbonate (EMC), EMC is beneficial for the room temperature performance, while the substitution of 20 vol % of EMC by ethyl acetate (EA) is good for the low temperature performance. When 30 vol % of DMC is substituted by 10 vol % of EMC and 20 vol % of EA, the exchange current density increases from 0.022 to 0.038 mA cm−2 at −20 °C, while the activation energy of the charge‐transfer process decreases from 48.36 to 33.01 kJ mol−1. Possible mechanisms for improving the electrochemical performance using different solvents have been analyzed. These results are significant for the exploration of appropriate electrolytes for the extensive applications of LiFePO4/C composite electrodes.