Electric carmaker BYD on Thursday signed a framework agreement to take part in lithium resource mining in Salt Lake in Northwest China's Qinghai Province.

BYD signed the deal with the Qinghai Salt Lake Industry Group Co at the ongoing Qinghai Investment Trade Talk on Green Development.

Under the agreement, the partners will take two to three years to build a plant with annual output of 30,000 tons of lithium carbonate, a raw material for making lithium batteries.

BYD, which is taking a 48 percent stake in the lithium mining project, wants to explore environmentally friendly battery technology.

The lake, which covers more than 5,000 square kilometers on the southern edge of the Qaidam Basin, has 14 million tons of lithium-associated resources. Qinghai Province wants to establish an industry capable of producing 200,000 tons a year of lithium carbonate from the lake.

Wang Chuanfu, president and founder of Shenzhen-based BYD, said that the growth in electric car sales has driven up the price of lithium batteries. The price of lithium carbonate rose from 40,000 yuan ($6,084) per ton to 150,000 yuan in 2015.