Single walled carbon nanotubes as supports for metal hydride electrodes

Abstract

The electrochemical generation and the storage of hydrogen employing metal hydrides has become a good alternative attending the requirement to search for new sources of clean energy. This work is devoted to study the hydrogen storage as hydrides in an AB 5-type metal alloy (MmNi 4.1Co 0.4Mn 0.4Al 0.5). The behaviour of the alloy containing electrode was evaluated employing several electrodes containing the alloy and diverse carbons. Carbons were prepared by using Single Walled Carbon Nanotubes (SWCNT) with different PTFE percentages (15%, 25% y 33%) and Carbon Vulcan XC72® with 33% of PTFE (VT). Several electrochemical techniques as Cyclic Voltammetry (CV), Charge–Discharge cycles and Electrochemical Impedance Spectroscopy (EIS) were used. Results demonstrate that at low discharge currents, electrodes containing SWCNT exhibit better hydrogen storage than Vulcan XC72® containing electrodes. Studies made with carbon supports only show that this little but not disregarded differences are related to different hydrogen sorption behaviour of SWCNT and Vulcan XC72®. From the kinetic point of view, Vulcan XC72® containing electrodes have a better behaviour than those prepared with SWCNT. On the other hand, the optimal percentage of PTFE for SWCNT was determined to be 25%.