Scientists promise lighter batteries

Scientists promise lighter batteries
Steve Bush US researchers have made a fundamental discovery in lithium ion (Liion) battery technology which promises lighter, cheaper batteries. Liion cells use a lithium-based ‘sponge’ on their cathodes to soak-up lithium ions during discharge. Common wisdom is that the sponge has to have a transition metal in its molecule as this is where ions are stored. LiCoO2, containing expensive cobalt, is the most common sponge material, although attempts are being made to replace the cobalt with cheaper manganese. “We have determined that the transition metal is not the host for the lithium ions. It is the oxygen in the molecule that stores them,” said Gerbrand Ceder, associate professor of materials science at the Massachussetts Institute of Technology (MIT). If true, this opens up a whole range of options for ion sponges. Principal among these, according to Ceder, is to replace part of the cobalt with lighter, cheaper aluminium. With its new understanding of ion storage, the MIT team is modelling sponge materials from first principles using quantum mechanics. “This is a superior way to identify and optimise new compounds over the traditional way of searching experimentally,” said Ceder. “A second generation material is under development which should offer a 300 to 400 per cent cost reduction over LiCoO2. We believe we are within 10 months of producing manufacturing samples to send out to battery makers.” With the backing of New Zealand’s Pacific Lithium, a technology company is being set up to commercialise the MIT materials.


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