Tesla Motors has said that it will partner with Chinese cell phone carrier Unicom to build charging outlets across the country.

Reuters reported that the companies have signed a deal to build charging posts at 400 China Unicom stores in 120 cities as well as set up super-charging outlets in 20 Chinese cities.

The provision of charging infrastructure in China is seen as key to growing sales of electric vehicles there.

Tesla chief Elon Musk has said he wants to invest heavily in a recharging infrastructure for the country where EV sales have been slow despite central and local government subsidies which started in 2009. An estimated 4,100 pure EVs were sold in China in the first quarter of this year.

CAAM, China’s association of automobile manufacturers, has previously admitted that the coordination required to develop a charging infrastructure would be challenging but Musk has said he hopes to be able to help launch a nationwide infrastructure as early as next year.