Electrochemical hydrogen storage of NdMg12–Ni composites modified with carbon nanotubes and BN particles

In this work, the electrochemical performance of NdMg12–Ni composite electrode in alkaline solution and the effect of the surface modification with carbon nanotubes (CNTs) and boron nitride (BN) particles on the NdMg12–Ni composite were investigated. The NdMg12 alloy was synthesized by a salt-cover-melting and a subsequent quenching process. The NdMg12–Ni–BN and NdMg12–Ni–CNTs composites were prepared by ball-milling NdMg12 alloy, Ni powders and CNTs or BN particles. It is found that CNTs or BN particles are mainly attached onto the surface of the NdMg12–Ni composite after the ball-milling process. The electrochemical experiment results indicate that the NdMg12–Ni composites modified with CNTs or BN particles have the improved electrochemical performance. In particular, the NdMg12–Ni–5 wt.% CNTs and NdMg12–Ni–3 wt.% BN composites have the higher initial discharge capacity of 416.6 mAh/g and 442.9 mAh/g, respectively, larger than the original NdMg12–Ni composite. The large amount of grain boundaries and crystalline defects, induced during the ball-milling process, can accelerate the bulk hydrogen diffusion and provide more surface active sites for the electrochemical reaction of the composites. However, the cycle stability of the composites modified by CNTs or BN particles is still not satisfactory for the practical application.