Researchers in France have shown that nanostructured electrodes could improve the performance of lithium-ion batteries. By increasing the power density by a factor of six compared with planar electrodes, the new electrodes could make the batteries – which are widely used in laptops and other portable devices – suitable for power tools, electric vehicles and other applications.

Patrice Simon and co-workers at the Université Paul Sabatier and the Université de Picardie Jules Verne electrodeposited 3D arrays of copper nanorods through porous alumina membranes, which acted as templates, onto copper foils. The nanorods were uniformly distributed with diameters down to 50 nm and heights of 1.8 microns. Each nanorod was then plated with polycrystalline magnetite (Fe3O4) – a cheap iron oxide with low toxicity that is found in rust. Electrochemical deposition allows the direct fabrication of a perfect junction between the copper nanorod and the Fe3O4.

In tests the electrodes showed excellent retention of capacity and recovery, sustaining over 100 charge/discharge cycles. The improved performance is caused by the enhanced chemical reaction rates made possible by the increased surface area of the electrode. The results suggest that the new electrode design could offer gains in battery capacity without sacrificing power or cycle life.