Method For Improving Discharge Performance Of High-rate Lithium Battery

Lithium-ion batteries have the advantages of high energy density, long cycle life, high open circuit voltage and low pollution. They have been used in small current discharge mobile communications, notebooks and digital cameras, but the high-rate discharge performance needs to be improved, so increase the high-rate What are the methods of lithium battery discharge performance?

1. The influence of lithium battery structure on high-rate discharge

When the battery is discharged at a high rate, the voltage drops sharply due to polarization, and the internal resistance of the battery needs to be minimized. Multiple tabs can be welded on the electrode pole pieces to reduce the internal resistance of the battery, increase the current density and speed up the charge transfer; but in actual operation, the positive and negative substrates are easily damaged, which affects the effect of large current discharge.

2. The influence of the ratio of the positive active material of the lithium battery with the conductive agent and the binder on the high current discharge

When the battery is discharged at high current, the internal resistance polarization is obvious, and the voltage drops sharply. Therefore, it is necessary to increase the conductivity of the positive and negative electrodes by adding conductive agent to reduce the polarization voltage; at the same time, the battery will generate heat when discharged at high current. Phenomenon, the positive and negative active materials may fall off during the cycle. In order to ensure the normal working voltage and ideal cycle life of the battery, it is necessary to properly mix active materials, conductive agents and binders.

3. The influence of plate surface density and compaction density

The areal density and compaction density of the positive and negative plates of lithium batteries have a great influence on the charge and discharge performance of the battery. The surface density and compaction density of the electrode plate are too large, although it is helpful to increase the energy density of the battery, but the electrolyte is difficult to penetrate into the electrode plate, resulting in the battery concentration polarization and internal resistance increase, and too dense active material During the cycle, due to the gradual infiltration of the electrolyte, swelling will occur, leading to shedding, resulting in a decrease in the battery charge and discharge performance; the surface density and compaction density of the electrode plate are too small, although it is beneficial to the penetration of the electrolyte and the reduction of the electrode Concentration polarization improves the high-current charge and discharge performance of the battery, but the energy density of the battery is low. It is necessary to design the areal density and compaction density of the electrode plate reasonably, and maximize the energy density of the battery under the premise of ensuring the high current discharge performance.

The method of improving the discharge performance of high-rate lithium batteries can reduce the internal resistance of the battery by changing the structure of the battery core. On this basis, the discharge platform can be improved by adjusting the ratio of active material and conductive agent; The surface density and compaction density of the electrode plate improve the high-current discharge performance.