| Summary: | 碩士 === 龍華科技大學 === 機械工程系碩士班 === 104 === This study uses solid state synthesis with high-temperature to synthesize the cathode material LiFePO4/C, and treats sunflower seed shells and carbonaceous materials of betel through mixing up microwave plasma of different powers. In these days, the plasma is widely applied in many fields, and in the system of microwave plasma, since the required temperature for process is low, the reaction can be simply made, the process can be easily done, and with the control of process parameters, it is possible to change the power of microwave plasma, it can be applied in the process.
During the experiment, the synthesized cathode material LiFePO4/C was mixed into 6 wt % of sunflower seeds and carbonaceous material of betel treated by microwave plasma, later, it was detected by XRD, SEM and made as CR-2032 coin battery for another characteristic detection of battery. The CR-2032 coin battery was processed with discharging test by different rates, and charge/discharge rates were 0.1C, 0.2C, 0.5C, 1C, 3C, and 5C, so the cut-off voltages for charge/discharge were respectively the detection conditions for 2V and 4.4 V. Base on the result, we know that when the charge/discharge rate increases, the capacity declines, and if the microwave plasma is mixed with cathode material LiFePO4/C to treat sunflower seed shells of 500W, under 5C of charge/discharge rate, the capacity is better than using mixed microwave plasma to treat sunflower nut shells from 100W to 300W. If the cathode material LiFePO4/C is mixed with microwave plasmas of 100W, 300W and 500W of betel nuts, when it is under charge/discharge rate 5C, the capacity performs stably and better than mixing cathode materials LiFePO4/C with microwave plasma to treat sunflower seed, therefore since its overall performance is better than sunflower seed carbonaceous materials, it will be the more ideal carbonaceous material, Then we processed 500 times of charge/discharge cycle test, and under the conditions that the discharging rates are both fixed as 0.2C, the cut-off voltages for charge/discharge were respectively the detection conditions for 2V and 4.4V. Based on the result of such charge/discharge cycle test, we found that, the capacity increases when we treat sunflower seed shells with microwave plasmas of different powers, and when we use the cathode material LiFePO4/C mixed with microwave plasma to treat 500W sunflower seed shells, it gains the better capacity and the longer capacity retention. Moreover, when we treat betel nut with microwave plasma, the capacities of three types of microwave plasmas were very close, and it was also 500W betel nut with a mixed power and longer capacity retention. Based on the test result, we can know that the carbonaceous material treated by mixed microwave plasma performs more stably and is the more ideal carbonaceous material.
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