BYD Co. opened a lithium battery plant in the northwestern province of Qinghai, which will be the world's biggest when construction is completed next year.

The factory, BYD's third, can eventually produce 24 gigawatt-hours of batteries a year, and is part of the company's plans to raise total production capacity to 60 GWh by 2020, it said in a statement Thursday.

BYD is building new battery production capacity to take advantage of China's aggressive new energy vehicle push, with the country desperate not only to cut air pollution from traditional combustion engines but also boost its high-tech clout.

BYD Chairman Wang Chuanfu told reporters last year that he expected all vehicles in China to be electrified by 2030.

Automakers sold 328,000 EVs in the first five months of this year, up 142 percent from a year earlier. EV ownership in China accounted for more than half of the global total last year.

The government is already warning of overcapacity risks, with a state planning agency official saying earlier this month that there were signs of "blind development" in the sector.