How Important of the Battery to the Electronic Devices?

Last weekend, during a casual meeting with some friends who are dealing in different industries, such as building constructions, electronic components, solution designer, etc. one of them asking what's the ICs, I told him that, the IC is a very smart small circuitry integrated with many functions, functioned as the brain of a human body, and our battery is functioning as the heart of human, to powering the whole electric product as requested. How do you think it? Thank you in advance. :-)