Poor batteries are the bane of smartphone users but a Singapore invention that could extend their life promises to be a game changer.

It involves restoring a battery that has reduced capacity due to repeated use. This could take up to 10 hours but need only be done once every few years when the power flags.

Such a process could be revolutionary as lithium-ion batteries are widely used, from smartphones to laptops to electric vehicles, said Professor Rachid Yazami, an adjunct scientist at Nanyang Technological University (NTU), who devised the innovation.

Prof Yazami, a 64-year-old French-Moroccan, told The Straits Times at NTU last Thursday that its greatest potential would be in electric vehicles.

"People don't change their cars as often as they do smartphones - some would change a phone every two years, but you would want a car to last for more than 10 years," said Prof Yazami, who is also the chief executive of battery technology firm KVI that was set up under NTU.

He said the technology is also environmentally friendly as fewer batteries would need to be made and disposed of.

His idea garnered interest from some of the world's leading electronics manufacturers, including Apple, Panasonic and Samsung, when he presented it at the International Battery Seminar in the United States in March last year.

The invention requires adding a third electrode on top of the two poles in typical lithium batteries. This third component is used to drain the residual lithium-ions in one of the poles which causes battery decline. By doing so, the battery can be restored to up to 95 per cent of its original capacity.

Adding a third electrode to drain the residual lithium-ions is an idea no one has thought of, just "like having a chicken with three legs", said Prof Yazami. A prototype battery with the third electrode for smartphones was built last June.

Prof Yazami believes his solution could be useful for iPhone users, given tech giant Apple's admission last month that it slowed down older models to prevent unexpected shutdowns due to ageing batteries. The firm recently slashed its price for replacement batteries from $118 to $38 until December this year.

But with this method of renewing batteries, fewer replacements might need to be made. "So maybe battery manufacturers will not like me, but the end users, the customers, I think they will like it," Prof Yazami said.

Dr Wesley Zheng, a scientist at the Agency for Science, Technology and Research's Institute of Materials Research and Engineering, who is known for his work in developing high-energy density lithium batteries, said Prof Yazami had taken a "very innovative approach".

"I believe that some manufacturers of lithium-ion batteries would be interested. It can significantly increase the lifetime of current lithium-ion batteries without requiring significant changes to their chemistry," Dr Zheng said.