Why does the anode make such a difference? I always picture it as a little thing at the top of the battery. Does it actually make up a large part of the batteries mass?
Isn’t the electrolyte where the energy is actually stored?
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
(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.
Isn’t the electrolyte where the energy is actually stored?