how do alkaline batteries have a charge but can’t be recharged?
In: Chemistry
The charge of an alkaline battery is the result of electrons moving from one chemical to another inside the battery; most alkaline batteries send electrons from zinc metal to manganese dioxide. This process chemically transforms both! The zinc is oxidized (similar to iron rusting) into zinc oxide, and the manganese dioxide is reduced to Mn2O3.
This process can, in fact, be reversed – you *can* recharge alkaline batteries by feeding electricity into them. But this reaction, and the battery the materials are contained in, aren’t designed for reversal. The Mn2O3 is much harder to push back into MnO2 and completely changing it all back into its original form isn’t feasible. Additionally, the reversed reaction is very exothermic (heat-generating) and is going to build up pressure, heat, and potentially small amounts of hydrogen gas. Hydrogen gas tends to explode under high heat and pressure (as any fan of German zeppelins will tell you), so this is not a very good idea.
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