High Performance Zr-based Metal Hydride Alloys For Nickel Metal Hydride Batteries

Abstract

ABSTRACTBased upon Ovonic's multi-element, atomic engineering approach, two families of alloys are being used in commercial Nickel Metal Hydride (NiMH) rechargeable batteries, i.e. the mischmetal (Mm) based AB5 and Zr based AB2 alloys. While Mm based alloys are faster to activate, are limited by a discharge capacity of only 320–340 mAh/g. The Zr based alloy, although slightly slower to activate, provides a much higher discharge capacity. In this paper, we first discuss the use of Ovonic's multi-element approach to generate a spectrum of disordered local environments. We then present experimental data to illustrate that through these atomically engineered local environments, we are able to control the hydrogen site occupancy, discharge capacity, kinetics, and surface states. The Zr based alloy with a specific discharge capacity of 465 mAh/g and excellent rate capability has been demonstrated.