What are the chemical reactions during the charging and discharging of nickel-cadmium batteries?

The chemical reaction in the discharge process (1) The negative electrode reaction The cadmium on the negative electrode loses two electrons and becomes the divalent cadmium ion Cd2+, and then immediately combines with the two hydroxide ions OH- in the solution to form cadmium hydroxide Cd(OH) ) 2. Deposited on the negative plate. (2) Positive reaction The active material on the positive plate is nickel hydroxide (NiOOH) crystals. Nickel is a positive trivalent ion (Ni3+), and every two nickel ions in the crystal lattice can obtain two electrons transferred from the negative electrode from the external circuit to generate two divalent ions 2Ni2+. At the same time, the two hydrogen ions ionized by every two water molecules in the solution enter the positive plate and combine with the two oxygen anions on the crystal lattice to generate two hydroxide ions, and then interact with the original two The hydroxide ions together with the two divalent nickel ions generate two nickel hydroxide crystals. Chemical reactions in the charging process When charging, the positive and negative electrodes of the battery are connected to the positive and negative electrodes of the charger respectively. The electrochemical reaction in the battery is completely opposite to that during discharge, that is, the negative electrode undergoes a reduction reaction and the positive electrode undergoes an oxidation reaction. (1) The cadmium hydroxide on the negative electrode plate is first ionized into cadmium ions and hydroxide ions during the negative electrode reaction charge, and then the cadmium ions obtain electrons from the external circuit to generate cadmium atoms attached to the plate, and hydroxide ions enter The solution participates in the positive electrode reaction. (2) The positive electrode reaction is used for the external power source. In the nickel hydroxide crystal lattice on the positive electrode plate, two divalent nickel ions each lose one electron to generate trivalent nickel ions. At the same time, two hydroxide ions in the crystal lattice Each releases a hydrogen ion, leaving oxygen anions on the lattice, and the released hydrogen ions combine with the hydroxide ions in the solution to generate water molecules. Then, the two trivalent nickel ions combine with the two oxygen anions and the remaining two hydroxide ions to form two nickel hydroxide crystals. Disclaimer: Some pictures and content of articles published on this site are from the Internet. If there is any infringement, please contact to delete. Previous: What are the steps for charging the battery of an electric vehicle?