What is the understanding of overcharge and overdischarge and its impact on battery performance?

Lithium battery protection board has battery overcharge protection function, over discharge protection function, over current protection function, short circuit protection function, temperature protection function, charge power balance management function, etc. In order to give you a better understanding of the function of the battery protection board, Guoren Chuangfa Technology Co., Ltd. will introduce what is overcharge, overdischarge, and what impact it has on battery performance.

Overcharge refers to the behavior of continuing to charge the battery after a certain charging process is fully charged. Since the capacity of the negative electrode is higher than the capacity of the positive electrode in the design, the gas generated by the positive electrode permeates through the separator paper and recombines with the cadmium produced by the negative electrode. Therefore, under normal circumstances, the internal pressure of the battery will not increase significantly, but if the charging current is too large or the charging time is too long, the oxygen generated is too late to be consumed, which may cause the internal pressure to rise, battery deformation, and liquid leakage. And other undesirable phenomena. At the same time, its electrical performance will also be significantly reduced.

After the battery has discharged the internally stored power, after the voltage reaches a certain value, the continued discharge will cause over-discharge, and the discharge cut-off voltage is usually determined according to the discharge current. 0.2C-2C discharge is generally set to 1.0V/branch, 3C and above, such as 5C or 10C discharge is set to 0.8V/branch, battery overdischarge may bring catastrophic consequences to the battery, especially high current overdischarge, or Repeated over-discharge has a greater impact on the battery. Generally speaking, over-discharge will increase the internal pressure of the battery, and the reversibility of the positive and negative active materials will be destroyed. Even if it is charged, it can only be partially restored, and the capacity will be significantly attenuated.