New technology restores aged lithium-ion batteries and extends cycle life
Due to the current development of lithium-ion battery technology, the portable electronic equipment and electric vehicle industry are booming, which has led to an increasing demand for lithium-ion batteries worldwide. However, the long-term use of lithium-ion battery products will cause the internal materials of the battery to age. This results in a decrease in the amount of electricity stored, which results in the replacement of a new battery after the product has been used for a period of time. At present, the common charging method in the market is constant current-constant voltage (CC-CV) charging method. However, when the charging current is ending at the constant current (CC) charging section, the internal solid electrolyte interface (SEI) of the battery is generated. The loss of lithium ions that can be circulated in the battery causes a decrease in battery cycle life.
Chen Baiduan et al., Department of Condensation Science, National Taiwan University, applied density functional theory to analyze and calculate the internal lithium ion mobility of lithium iron phosphate (LiFePO4) cells, and established a sine wave charging model. This model introduces a negative voltage to suppress during charging. Generation of a passivation layer.
Researchers compare the battery capacity of the sine wave charging method with the traditional CC-CV charging method to compare the battery capacity of the electric vehicle with a battery capacity of less than 80%, and simulate the electric motor by charging and discharging the battery with a large current. According to the experimental results, the traditional CC-CV charging method can reach 80% capacity after 600 cycles, while the battery using the sine wave charging method has 95% of the remaining capacity, indicating that the sine wave charging method is for the battery. It has an extended effect on the service life.
In addition, the battery that has been eliminated from the electric vehicle can be charged by the sine wave charging method, and the capacity can be increased by up to 18.7%. The sine wave is charged during the charging process, the battery temperature rises up to 9 °C, and the charging time only needs half of the traditional CC-CV charging method time, and its performance is better than the traditional CC-CV charging method.
To verify the effect of the sinusoidal charging method on the internal SEI membrane impedance of the battery, the researchers analyzed the battery using electrochemical impedance spectroscopy (EIS). The results showed that the battery after 600 cycles using this charging method was compared to the conventional CC- The CV battery effectively suppresses the growth of the SEI film and maintains a level close to that of the new battery. This indicates that the charging method has less damage to the internal material structure of the lithium ion battery and provides a longer battery life. Therefore, the charging method will provide a better choice for users of lithium ion battery products.