Pee-powered battery smaller than a credit card
To activate the battery, a drop of urine is added and soaks through the sandwiched filter paper. The chemicals dissolve and react to produce electricity. The magnesium layer acts as the anode, losing its electrons. And the copper chloride acts as the cathode, mopping up the electrons.
I can just imagine myself:
“Damn my cell phone is dying… hold on let me pee on it”
