(Towards) structural resolution of inter-layer H2O in electroactive transition-metal hydroxides

We seek to utilise neutron scattering to elucidate the structure of water in Ni(OH)2 phases in order to understand its role and determine whether electrolyte salt choice can lead to improving material stability. Ni(OH)2 is a layered material that has been studied for a variety of electrochemical applications, including nickel-based batteries, supercapacitors, electrochromic devices and electrocatalysts. Most notably this material is used in the battery of the Toyota Prius. Due to observed phase changes during electrochemical cycling, the more stable beta-NiOOH/beta-Ni(OH)2 transition, with lower charge capacity, is utilised in battery applications instead of the more desirable gamma-Ni(OH)2/alpha-Ni(OH)2 couple. From experiments undertaken in the past few years evidence strongly suggests that water within the crystal structure plays an important role in the stability of Ni(OH)2 phases.