The role of Mn in C14 Laves phase multi-component alloys for NiMH battery application

Abstract

The role of Mn in C14 Laves phase alloys for battery applications was studied by adjusting the Mn content in exchange with Ni and Cr in three series of C14 AB2 Laves phase alloys. Additional B-modifiers, such as Sn, Co, and Al as a group, were also compared to Mn using AB2 MH alloys in a nickel metal hydride (NiMH) battery. In all cases, higher Mn content degraded the cycle life performance while marginally increasing the discharge capacity. Without the presence of other modifiers, such as Sn, Co, and Al, Mn proved to be detrimental to both charge retention and activation of Ti-based C14 Laves phase MH alloys. However, in combination with Sn, Co, and Al; Mn contributed positively to charge retention while activation remained at a manageable level. It has also been shown a lower Mn and higher Ni content improved the specific power and low temperature performance, whereas increasing Cr content at the expense of Mn improved cycle life and charge retention in a NiMH battery.