by Farhad Manjoo Slate
Batteries are terrible. Compared to many other methods of storing energy, especially fossil fuels, batteries aren’t very energy dense – that is, a 1-pound battery stores far less energy than is contained in a pound of gasoline. That wouldn’t be so bad if the energy in a battery were easy to replenish – your Tesla might still go only a couple hundred miles on a single charge, but if you could fully recharge it in five minutes rather than several hours, the low capacity wouldn’t bother you as much.
Scientists have spent decades trying to create the perfect battery – a battery with great energy density or, at least, one that doesn’t take so long to charge. If we could somehow make this perfect battery, pretty much every gadget you use, from your phone to your laptop to your future electric car, would be amazing, or just less annoying than they are today. The perfect battery might also help with some other important stuff: climate change, oil wars, pollution, etc.
One approach for improving the battery is to forget about the battery and instead improve capacitors. A capacitor, like a battery, is a device that stores electrical energy. But capacitors charge and discharge their energy an order of magnitude faster than batteries. So if your phone contained a capacitor rather than a battery, you’d charge it up in a few seconds rather than an hour. But capacitors have a big downside – they’re even less energy dense than batteries. You can’t run a phone off a capacitor unless you wanted a phone bigger than a breadbox.