A material for large-scale lithium ion battery applications has been studied at the atomic level to explain exactly how it works so well.

With the potential for use in hybrid electric vehicles, solar-energy storage and emergency power supplies there is a need for larger and cheaper rechargeable lithium ion batteries, explained Josh Thomas of Uppsala University, Sweden. With colleagues at the CNRS, France, he worked to develop and understand iron silicate, specifically Li₂FeSiO₄, electrodes.

The current materials used in these batteries are, according to Thomas, 'prohibitively expensive' for large scale commercial applications. His aim is to 'make larger lithium ion batteries an economically viable proposition'.

Russell Egdell, professor of inorganic chemistry at Oxford University, said that Thomas used photoelectron spectroscopy, PES, to demonstrate how the 'excellent reversibility' of Li₂FeSiO₄ electrodes is related to 'fundamental surface processes'.

Other electrode materials can develop a film on their surface over time. This film, a result of an irreversible reaction between electrode and electrolyte, results in a decrease in battery efficiency.

Thomas showed that iron silicate cathodes do not lose capacity in this way, only reacting with trace solvent and not electrolyte salt.

Thomas said that Li₂FeSiO₄ is now confirmed as a 'highly promising and potentially cheap' cathode material for use in large-scale applications of lithium ion batteries in which current materials would prove too costly.

Suzanne Abbott