New coating could make smartphone's battery last longer

A new coating for batteries could improve energy and weight efficiency in our smartphones and electric vehicles, say scientists.

Researchers at the University of California Riverside are using an organic compound called methyl viologen to cover the metal on the negative charged side of batteries – the anode – to optimise lithium-ion batteries.

"It is low cost, easily manipulated and compatible with the current lithium ion battery industry," said Chao Wang, chemist at the university and lead author of the study.

Anodes of lithium-ion batteries are traditionally made with graphite or other carbon-based material, but this usually takes up a lot of weight and energy density, limiting energy storage.

So Wang’s team suggests using lithium-metal anodes instead, that are both cheaper and have bigger capacity. The move, they say, enables smartphone and electric vehicle batteries to last up to 10 times longer.

However, using metals for lithium-ion anodes leads to the formation of dendrites - branched fibres in a tree-like structure - that cause degradation of the battery and can make it catch on fire in some cases.

The Riverside team overcame this issue by coating the metal with 0.5% methyl viologen, which stabilises the anode by reacting with the lithium to remove oxygen molecules.  

The coating eliminated dendrite growth and increased the battery lifetime by more than three times, said the scientists.

The study has been published in the journal Chemistry of Materials.