Can chemical energy from food be stored in a battery?
Three ways to turn chemically stored energy into electricity:

a fuel cell: While that works fine for hydrogen or methanol, I'm not sure if sugars are possible, and general &quot;food&quot; won't work. Of course you can chemically convert food into hydrogen or alcohol, or into sth. very specially designed to power a biofuel cell.
dry, burn, run a turbine or steam engine with attached generator, very obvious and simple.
direct conversion into mechanical energy via an artificial muscle, which powers a generator. Horribly complicated (bio-)chemistry, theoretically possible, because our body does it, too.