Hitachi Cable Develops New Rolled Cu Foil for Next Generation Li Battery

Hitachi Cable announced on Tuesday the firm developed a new rolled copper foil with high intensity and high heat resistance which can be applied to next generation lithium ion secondary batteries. The firm adopted its original copper alloy HCL02Z containing zirconium at 0.02% and gave an original surface treatment for the foil. By these inventions, the new foil represents good chemistry with negative-electrode active materials of next generation Li ion secondary batteries, such as silicon. As a result, a battery’s life improved by more than 10% compared with another battery using an electrolytic copper foil as a negative current collector by Hitachi Cable’s test.

Negative-electrode active materials are adhered on a copper foil of a negative current collector. For conventional Li ion secondary batteries, carbon based materials are mainly used as negative-electrode active materials. Meanwhile, alloy materials such as silicon are likely to be used for next generation batteries to gain higher energy density. Alloy materials widely change the cubic volume along temperature fluctuation. Then, after repeating charge and discharge, alloy materials tend to separate from copper foil and shorten the battery’s lifetime.

Hitachi Cable succeeded in development of a new copper foil using HCL02Z, which is as thin as 8-10 micrometers while represents higher intensity and heat resistance than a rolled pure copper foil or an electrolytic copper foil. The new foil doesn’t soften and change its shape in the productive processes of Li ion batteries. At the same time, Hitachi Cable gave a surface treatment to realize better adhesion between a foil and an electrode active material.

Next generation Li ion secondary batteries are expected to be used for mobile devices and ecology cars.