The cathode and anode of a battery are not just the little metal terminals; they are the sites where the electrochemical reaction takes place, and where the ene

The cathode and anode of a battery are not just the little metal terminals; they are the sites where the electrochemical reaction takes place, and where the energy is stored. Even in an old-fashioned alkaline battery, they run the entire length of the cell: https://en.wikipedia.org/wiki/Alkaline_battery#Chemistry https://en.wikipedia.org/wiki/Alkaline_battery#Chemistry (For one thing, the surface area of contact between the electrodes and electrolyte is a limiting factor for how fast the reaction can proceed, and therefore how much current the battery can produce.) In a lithium-ion battery, the cathode and anode are typically constructed out of many stacked layers, separated only by a very thin layer of electrolyte.