Enhanced C-rate capability and long-term cycling behavior of LiFePO4/ C-BaTiO3 composite cathode

초록

Among the cathode materials that account for the largest cost in lithium-ion battery materials, olivine-structure LiFePO4 (LFP) have gained attention as a major cathode material for lithium-ion batteries due to its excellent thermal cycle performance and low price. However, carbon coating is essential because LFP exhibits low lithiumion mobility due to its structural properties. Nevertheless, carbon-coated LFP (LFP/C) still suffers from rapid capacity decay at high C-rates. In this study, the LFP/C was mixed with perovskite ferroelectric BaTiO3 (BT) to manufacture a composite cathode material with improved electrochemical properties. BT forms a dipole moment due to its high dielectric constant, LFP surface is induced to attract more positive charges. As a result, improves the lithium mobility coefficient, a drawback of LFP. The LFP/C-BT composite containing 5 wt% of BT showed an initial capacity of 154.3 mAh/g at 0.1C, a capacity of 88.3 mAh/g at 10C and capacity retention of 74.2 % after 500 cycles at 5C. Additionally, further electrochemical analysis was conducted after the cycling to confirm the improvement in electrochemical performance due to the addition of BT. This composite cathode took advantage of simplifying the process through a composite method instead of the existing coating method, and it was confirmed that the BT composite showed similar effects to coating after cycling.

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