Batteries are just chemical reactions that produce electricity. In electrochemical cells, redox reactions - where electrons transfer - generate electrical current. This is the basis of batteries, electroplating, and corrosion.
Voltaic (galvanic) cells generate electricity spontaneously. Electrolytic cells need external power to drive reactions.
Real Applications
Your phone battery, car battery, and even the corrosion on old cars - all electrochemistry. Understanding it helps us make better batteries and prevent damage.