Two Chinese companies have announced the launch of production of a new additive for single wall carbon nanotube batteries.

The new additive, which is based on graphene, is said to improve the performance of single wall carbon nanotube batteries by up to 30%.

The two companies, Beijing-based Global Graphene Group and Shenzhen-based SFC Energy, say that the new additive will help to improve the energy density of single wall carbon nanotube batteries, as well as their overall performance and lifespan.

According to the companies, the new additive will be used in a new generation of battery cells that are currently under development.

The launch of production of the new additive comes as the global market for electric vehicles is expected to grow rapidly in the coming years.

Global sales of electric vehicles are expected to reach 2 million by 2025, up from around 1 million in 2015, according to a report by Bloomberg New Energy Finance.

The new additive is just one of a number of new technologies that are being developed to improve the performance of batteries for electric vehicles.

Others include solid-state batteries and lithium-air batteries.