New Alloy Could Be Battery Ally

In a classic case of a mistake leading to a better solution, scientists have developed a new metal alloy that could enhance the performance of rechargeable nickel/metal hybride (Ni/MHx) batteries. The alloy lacks cobalt, making it less expensive than current models, and no cadmium, a toxic metal found in nickel-cadmium batteries.

Researchers made the discovery while exploring ways to improve both charge-storing capacity and repeat-charging capabilities of Ni/MHx batteries. They hoped to improve performance by adjusting the composition of the batteries' electrode. Composed of a core of nickel surrounded on the periphery with lanthanum, these electrodes corrode over time due to the expansion and contraction of molecules caused by repeated charging and discharging.

Initially, the scientists found that by combining a number of metals with the nickel made for a more resilient electrode. However, one of the metals, cobalt, was cost prohibitive. While investigating cobalt-free alternatives, researchers found a combination of lanthanum, nickel and tin with a high storage capacity that didn't decay over time.

Further study revealed that this new alloy actually contains a slightly higher ratio of nickel and tin than had been intended. The result is that batteries incorporating this new alloy in the electrode have a higher long-term energy-storage capacity than commercial models using cobalt alloys.

From Pure Power, Fall 2002