Is it harmful to overcharge the Ni-MH battery?

When the Ni-MH battery is overcharged, the internal gas recombination of the battery can maintain the internal pressure balance of the battery. Because, when overcharged, the positive plate of the battery will undergo an oxygen evolution reaction. The precipitated oxygen reaches the surface of the negative electrode through the porous separator. Due to the excessive design capacity of the negative electrode, 40T-2H20+Q+4e will not be able to absorb hydrogen in the negative electrode and cause hydrogen atoms to recombine into hydrogen and precipitate during the charging process, but the oxygen that reaches the surface of the negative electrode and the metal hydride undergo an oxidation-reduction reaction. 4MI+Q-u003e4M+2H20 nickel is a good catalyst for the above reaction. After the MH-Ni battery is activated, the concentration of metallic nickel in the surface layer of the hydrogen storage alloy is greatly increased. When the battery is overcharged, the hydrogen atoms adsorbed on the surface of the metal nickel increase, which is beneficial to the reaction. Therefore, the internal pressure of the battery will not increase due to oxygen evolution. The total reaction during overcharge is 4M+2H20-) O2+4MH overcharge, the material inside the battery is not reduced due to the oxygen evolution of the positive electrode, but the material balance is achieved through the appearance and consumption of oxygen. In the above decomposition, it is assumed that the negative electrode does not release hydrogen when the battery is overcharged. However, with regard to hydrogen storage alloy electrodes with poor battery formation and poor catalytic performance on the surface of the metal hydride electrode, the charging efficiency and charging capacity will be greatly affected. When the charge level reaches a certain level, too much overpotential will cause hydrogen gas to appear in the negative electrode, and the rate of hydrogen gas being consumed on the positive electrode or absorbed again by the negative electrode is slow. Therefore, when the battery is overcharged, more hydrogen is precipitated, and the oxygen cannot be effectively consumed by the negative electrode, causing the internal pressure to rise rapidly, and finally the battery leaks. Disclaimer: Some pictures and content of the articles published on this site are from the Internet. If there is any infringement, please contact to delete.