When researcher Yang Shen examined old rechargeable batteries that had stopped working, he discovered that they were basically completely intact.

They had not corroded as he thought.  

Together with his supervisor Dag Noréus at Stockholm University, he tested filling the battery with oxygen to restore the balance in the battery. 

- We were a little surprised that it went so well to add oxygen to the battery.

It was a bit of a heureka.

The next step became quite obvious, that you can use the technology to restore electron balance and electrolyte in batteries, says Dag Noréus, professor of inorganic chemistry.  

NiMH batteries 

The experiments are performed on hybrid batteries, so-called NiMH batteries.

This type of battery was standard before we switched to lithium-ion batteries in most mobile phones and electric cars.  

Lithium-ion batteries have many advantages, they are extremely efficient, and weigh less because they can produce more energy in less space.  

But there are other benefits to hybrid batteries, according to researchers.

They have a long life and are easier to recycle because they can be disassembled and do not need to be melted down in the same way as lithium-ion batteries.  

—I think this discovery may be of great significance.

Nickel-metal hybrid batteries are growing strongly following increased demands for backup energy in transport such as rail and wind power, says Mats Sandberg, battery researcher at RISE. 

Develops new battery 

Yang Shen, who developed the oxygen technology, is now working at the Swedish company Nilar to develop a long-lasting NiMH battery for electricity storage.

The batteries they develop are primarily intended for use in storing renewable electricity. 

Read more about battery research here.