Building better batteries

The rechargeable lithium ion batteries commonly used in portable devices, such as mp3 players and digital cameras, deliver power only for a short time before they need recharging. More frustrating is that with continued use, these batteries also lose the ability to accept a full recharge. Now, scientists in Italy may have found a possible solution to both problems that involves a few changes to the chemistry of the electrodes and the electrolyte.

In rechargeable lithium batteries, the positive electrode is commonly made of lithium cobalt oxide, the negative electrode of carbon, and the electrolyte is an organic solvent. In use, lithium ions migrate from the positive electrode to the negative electrode, producing an electric current as they do so. In the reverse process, to recharge the battery, positive lithium ions are now pushed through the electrolyte from the negative to the positive electrode by an external current. The build-up of lithium metal deposits on the negative electrode eventually causes these batteries to fail.