In a discharing battery, the process is a decoupled redox chemistry reaction. Instead of having reactants contacting each other, a wire is provided for eletron transferring and an eletrolyte is provided for ions tranferrring. The reaction is driven forward by the chemical potential, a energy...
I have to say that the picture of Haiha is about a supercapacitor. The electric double layer theory can be found anywhere for supercap. In a capacitor, both electrodes are oppositely charged. There is an electric field between charged items. There is NOT any electric field between two neutral...