LG Chem has purchased shares worth 40 billion won ($35.5 million) in Jiujiang DeFu Technology, a Chinese firm that manufactures copper foils for electric vehicle batteries, the firm said Sunday.

A copper foil is a sheet of copper 15 times thinner than a strand of hair. Copper foil is where electricity flows in battery’s anodes, or the negative side. The thinner the copper foils are, the more materials can be packed inside, making batteries more powerful.

DeFu is the No. 3 copper foil maker in China and runs two production facilities in the country, where it produces copper foils for EVs and prints circuit boards that go inside electric devices such as smartphones, according to LG Chem.

“DeFu’s current annual production capacity stands at 49,000 metric tons, which will increase to 78,000 tons by next year. Its first quarter sales logged 113 billion won, which more than quadrupled compared to a year prior,” an LG Chem official said.

The official added that DeFu is the only Chinse copper foil manufacturer with independent technology for chemical additives used during the manufacturing process of copper foils.

According to Hana Financial Investment, the global EV battery copper foil market will increase to 620,000 tons by 2025 from the current 260,000 tons.

By Kim Byung-wook (kbw@heraldcorp.com)