Pulse charging curve of lithium battery

Pulse charging curve of lithium battery
During constant current charging, the battery is charged with a constant current, and most of the energy is transferred to the inside of the battery. When the battery voltage rises to the upper limit voltage (4.2V), it enters the pulse charging mode: intermittently charging the battery with a 1C pulse current. The battery voltage will continuously increase within a constant charging time Tc, and the voltage will slowly decrease when charging stops. When the battery voltage drops to the upper limit voltage (4.2V), charge the battery with the same current value and start the next charging cycle. Repeat the charging process until the battery is fully charged.

During the pulse charging process, the rate of voltage drop in the battery will gradually slow down, and the stop charging time T0 will become longer. When the constant current charging duty cycle drops to 5% to 10%, it is considered that the battery is fully charged and the charging will be terminated. Compared with conventional charging methods, pulse charging can charge with a larger current. During the shutdown period, the concentration polarization and Ohmic polarization of the battery will be eliminated, making the next round of charging smoother. The charging speed is fast, the temperature change is small, and the impact on battery life is small. Therefore, it is widely used nowadays. But its drawbacks are obvious: it requires a power supply with limited current function, which increases the cost of pulse charging.

C. The pulse charging studied by K. Leong et al. lasts for approximately 1 second per charging cycle. The battery is first charged in the forward direction, and then stopped and discharged in the reverse direction for 20-30 milliseconds each. The positive pulse current charges the battery, while the negative pulse current reduces gas precipitation from the electrode, allowing for fast charging of the battery with higher currents.