Can copper-zinc be substituted for silver-zinc?
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).