Tiny copper foil, big role: Building the foundation of advanced manufacturing

A sheet of copper foil just five microns thick may look insignificant, but it plays a crucial role inside the batteries powering new energy vehicles.

Thinner than a human hair and about one twenty-first the thickness of a sheet of A4 paper, the ultra-thin copper foil helps improve battery energy density, extend driving range and enhance safety.

"Reducing the thickness from 8 microns to 5 microns can increase a battery's energy density by at least 12 percent," said Li Zehua, deputy factory manager of the Copper Foil Branch Plant at Jinchuan Group. "The thinner the copper foil, the higher the battery's energy density."

Behind this tiny material lies a much bigger story, one about critical resources, advanced manufacturing and industrial resilience.

In Jinchang, Northwest China's Gansu province, Jinchuan Group has built an integrated industrial chain covering mining, mineral processing, smelting, advanced materials manufacturing and resource recycling, turning raw resources into high-value materials for emerging industries.

"Our copper foil facility is designed to produce 10,000 metric tons annually, including 5,000 tons of lithium battery copper foil products used in electric vehicles and consumer electronics," Li said.

Engineers at the plant have reduced copper foil thickness from 12 microns to 5 microns while maintaining a purity level of 99.99 percent. The thinner foil allows batteries to store more energy within the same space, improving overall performance.

Producing ultra-thin copper foil, however, is about more than reducing thickness. Even tiny surface defects such as bumps or pinholes can compromise battery safety, requiring continuous improvements in equipment, manufacturing processes and quality control. Today, about 90 percent of the equipment used at the facility is domestically manufactured.

Jinchang is rich in strategic metals such as nickel, copper and cobalt, which are widely used in new energy, aerospace and other advanced manufacturing industries.

"We have established a fully integrated industrial chain that covers everything from mining and mineral processing to smelting, advanced materials manufacturing and resource recycling," said Jin Hongxiang, deputy general manager of the Strategic Planning Department at Jinchuan Group.

"That enables us to better safeguard strategic mineral resources, improve self-reliance in critical materials, support the upgrading of advanced manufacturing and advance the development of a greener, more circular industrial system," Jin said.

Hu Yumeng contributed to the story.