A powerful experimental battery that can be recharged completely in minutes

Mar 24th 2011 | from the print edition

ENGINEERS have long dreamed of shortening the time it takes to recharge batteries. Currently, that can be hours. For applications like motor vehicles it really needs to be reduced to minutes. Now Paul Braun and his colleagues at the University of Illinois, Urbana-Champaign, have succeeded in building prototype batteries which do just that. Their most successful attempt can be recharged almost fully in a mere two minutes.
All batteries, no matter what their exact composition, work in the same fundamental way. They have two electrodes, an anode and a cathode, that are connected by an electrically conductive material—generally a liquid—called an electrolyte. When a battery is discharging, electrons (which are negatively charged) flow from anode to cathode through an external circuit, where they are put to work, and positively charged ions flow from anode to cathode through the electrolyte, to balance the charges in both electrodes. During recharging, electrons are forced round the circuit in the opposite direction, and the ions, perforce, return whence they came.

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