Electronic – Can copper-zinc be substituted for silver-zinc


Silver-zinc batteries are in the news (the pop science news) these days because they are being researched to compete with lithium ion batteries. But the price is high because silver is expensive. So it got me thinking about copper.

Just quoting the values as given by wikipedia:

Copper has an electronegativity of 1.9 and resistivity of 16.78 nΩm.

Silver has an electronegativity of 1.93 and resistivity of 15.87 nΩm.

They seem really similar. Can't the copper-zinc chemistry substitute for the silver-zinc chemistry? Wouldn't this have similar performance in a battery (either primary or rechargeable)?

I'll finally note that copper-zinc is one of the oldest battery chemistries ever built, all the way back in 1800 by Alessandro Volta. So I'm suspicious that there's something not so great about it (or otherwise silver-zinc wouldn't be needed). I just don't know what it might be.

Best Answer

During the charging process, silver is first oxidized to silver(I) oxide: 2Ag(s) + 2OH− → Ag2O + H2O + 2e− and then to silver(II) oxide: Ag2O + 2OH− → 2AgO + H2O + 2e−, while the zinc oxide is reduced to metallic zinc: 2Zn(OH)2 + 4e− = 2Zn + 4OH−.

AgO and Ag2O i stronger oxidant than Cu2O and CuO, so they can reach higher voltage from cell. You have to look at Standard electrode potential: https://en.wikipedia.org/wiki/Standard_electrode_potential_(data_page) You can build copper oxide - zinc battery, but it have only some about 0.8V per cell (but have strong current capability).