Testing of the performance and energy-storage applied for retired LiFePO4 batteries

The capacity, DC internal resistance and storage performance at room temperature have been tested for LiFePO₄ batteries retired from electric bus. The charge/discharge rate performance, temperature performance, cycle performance have also been tested. The difference and change regulation of parameter between new batteries and retired batteries have also been analyzed. Then the batteries were recombined and the cycle performance of model have been tested. 1 MW·h secondary use batteried energy-storage system were integrated and participated in wind-power smoothing. The results show that DC internal resistance of battery increase a little, storage performance at room temperature, rate performance and temperature performance decrease slightly, the cycle performance of cell and model is still good, when the capacity of LiFePO₄ battery decreased to about 75% of the initial capacity. These results show that the retired EV batteries has good reuse value.