Effect of mechanical activation process parameters on the properties of LiFePO4 cathode material |
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Authors: | Jae-Kwang Kim Gouri Cheruvally Jae-Won Choi Jong-Uk Kim Jou-Hyeon Ahn Gyu-Bong Cho Ki-Won Kim Hyo-Jun Ahn |
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Affiliation: | 1. Department of Chemical and Biological Engineering, ITRC for Energy Storage and Conversion, Gyeongsang National University, 900 Gajwa-dong, Jinju 660-701, Republic of Korea;2. Division of Advanced Materials Science and Engineering, ITRC for Energy Storage and Conversion, Gyeongsang National University, 900 Gajwa-dong, Jinju 660-701, Republic of Korea |
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Abstract: | Pure, nano-sized LiFePO4 and carbon-coated LiFePO4 (LiFePO4/C) positive electrode (cathode) materials are synthesized by a mechanical activation process that consists of high-energy ball milling and firing steps. The influence of the processing parameters such as firing temperature, firing time and ball-milling time on the structure, particle size, morphology and electrochemical performance of the active material is investigated. An increase in firing temperature causes a pronounced growth in particle size, especially above 600 °C. A firing time longer than 10 h at 600 °C results in particle agglomeration; whereas, a ball milling time longer than 15 h does not further reduce the particle size. The electrochemical properties also vary considerably depending on these parameters and the highest initial discharge capacity is obtained with a LiFePO4/C sample prepared by ball milling for 15 h and firing for 10 h at 600 °C. Comparison of the cyclic voltammograms of LiFePO4 and LiFePO4/C shows enhanced reaction kinetics and reversibility for the carbon-coated sample. Good cycle performance is exhibited by LiFePO4/C in lithium batteries cycled at room temperature. At the high current density of 2C, an initial discharge capacity of 125 mAh g−1 (73.5% of theoretical capacity) is obtained with a low capacity fading of 0.18% per cycle over 55 cycles. |
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Keywords: | LiFePO4 Mechanical activation Rechargeable lithium battery Discharge capacity Cathode material Cycling performance |
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