Ni-based secondary batteries are currently used in many applications, however, the structural changes at the electrodes are not fully characterized and neutron diffraction is a suitable technique to readdress this matter.We have constructed a new electrochemical cell for neutron diffraction specially designed for POLARIS with the aim to get a clear picture of the role of deuterium at the electrodes during battery operation. Our preliminary electrochemical and ex-situ XRD results show that two Ni-based batteries, Ni(OH)2/MH and Ni-mesh/MH where M is an alloy, work as expected in our new cell. Both batteries will be charge/discharge at different current rates, C/24 and C/12, to investigate the effect of diffusion kinetics on the final neutron diffraction pattern. The use of POLARIS is motivated by its high flux that will allow experiments to be performed with short counting times.