A nanocrystal coating of cobalt improves the performance of nickel-rich rechargeable batteries.

The batteries in many electric vehicles and mobile phones work by circulating lithium ions between two charged materials — the negative anode, often made of graphite, and a positively charged cathode, of cobalt or manganese oxide. Nickel-rich oxides have grown in popularity for use in cathodes because they are cheap and effective. But they quickly crack and dissolve, which reduces battery capacity.

Jaephil Cho at the Ulsan National Institute of Science and Technology in South Korea and his colleagues developed a cathode composed of more than 80% nickel. The researchers coated it with nanoscale cobalt crystals, which limited degradation. This allowed the battery to retain 86% of its capacity after being recharged 400 times at room temperature.

The authors say that nickel-rich cathodes could help to meet growing demand for rechargeable batteries in electric vehicles as cobalt prices rise.