Secondary batteries* are commonly used in our daily lives for electric cars, smartphones, tablet PCs, and more. One of the key materials that influence the price and performance of this battery is the ‘copper foil (battery foil)’ that surrounds the cathode material. The reason for this is that the thinner the copper foil, the lighter the battery becomes, and the wider and longer it is, the longer the battery life and capacity increase.

*A rechargeable battery, storage battery, or secondary cell (formally a type of energy accumulator), is a type of electrical battery that can be charged, discharged into a load, and recharged many times, as opposed to a disposable or primary battery, which is supplied fully charged and discarded after use.

Copper foil refers to a film made by melting copper and spreading it thinly to about 1/20th the thickness of a hair. It is used as a current collector surrounding the cathode of a secondary battery. In other words, copper foil is the copper film that surrounds the cathode material in a secondary battery. This serves as the pathway for electron movement during battery charging and discharging, as well as playing a role in releasing the heat generated within the battery to the outside.

As about 40kg of copper foil is used for one electric vehicle, the growing global electric vehicle market is expected to drive demand for copper foil. In response, the industry is actively expanding production capacity to meet this demand. According to market research firm SNE Research, the global market for secondary battery copper foil is predicted to experience a high annual growth rate of over 40%, increasing from around 270,000 tons in 2021 to about 750,000 tons in 2025.

In the copper foil industry, creating thin, smooth, and uniformly thick copper foil is considered a core technology. However, the thinner the copper foil, the greater the risk of tearing and wrinkling, making it an industry that requires advanced process control technology and equipment competitiveness.

In the case of Korea Zinc’s electrolytic copper foil, copper is dissolved in sulfuric acid and then subjected to electrolysis before being plated onto a titanium drum. This process closely resembles the ‘electrolysis process’* of the zinc smelting process, which is Korea Zinc’s main business. Korea Zinc produces exceptionally high-quality and stable secondary battery copper foil, based on its proprietary technological expertise and know-how accumulated in the non-ferrous metal smelting industry.

*Electrolysis Process: Electroplating a zinc solution, which has undergone liquid treatment, onto an aluminum cathode plate through electrolysis in an electrolytic cell.

Furthermore, the copper foil produced by Korea Zinc is aimed at promoting a circular economy. This is achieved by using copper (Cu) extracted from various sources such as waste batteries, process scraps, smelting by-products, electronic scraps, and waste electrical wires. Additionally, the advantage of internally producing electrolytic copper*, and sulfuric acid, which are raw materials used in copper foil, contributes not only to a strong competitive pricing but also forms the foundation for a stable and reliable supply of the product.

*Electrolytic Copper: Copper refined through electrolysis with a purity of over 99.95%.

In March 2020, Korea Zinc established KZAM, its subsidiary responsible for the production and sales of the company’s copper foil, securing essential facilities for copper foil production and continually increasing investments. KZAM plans to expand its factory capacity to increase annual production from 13,000 tons to 60,000 tons by 2027.