It was more than two years ago that we first heard of a potential battery breakthrough developed by Stanford University professor Yi Cui using carbon nanowires. The bundles of nanowires that comprise the battery anode have more room to swell while absorbing lithium ions without cracking, enhancing the energy storage capacity and lifespan of the battery.
Since 2007, Cui and other researchers at Stanford have been working on new cathode materials that can help to take advantage of the properties of the nanowire anode. They have now developed a lithium sulfide electrode that, in combination with the anode, increases the energy density of the battery by a factor of four.
The new lithium sulfide material also resists the safety issues associated with high-capacity lithium ion batteries. Metallic lithium grows crystal structures during charge and discharge cycles that can pierce the separator materials between the electrodes, which can cause shorts and the thermal incidents (aka fires) that we have seen in some consumer electronics devices. The non-metallic lithium sulfide compound doesn't have this characteristic, making the new batteries safer.
The team now has to find away to make the battery last more then 40-50 charge cycles by stopping the production of poly-sulfides during charge-discharge. It will likely be quite some time before we see these types of batteries commercialized.
[Source: Nano Letters via Technology Review]