Electrochemical performance of pseudo-capacitor electrodes fabricated by Electrophoretic Deposition inducing Ni(OH)2 nanoplatelets agglomeration by Layer-by-Layer

The electrochemical behaviour of ceramic semiconductors not only depends on the characteristics of the electroactive material but also on the processing method, the nanoparticles arrangement and the consolidation degree of the formed microstructure. In this sense, the use of nanoparticles with plane morphologies (disc, platelets, etc.) results interesting due to the formation of conduction pathways produced as a consequence of their laminar structures. Electrophoretic Deposition (EPD) is a shaping methodology which allows achieving high degrees in nanoplatelets packing by controlling their alignment during the coating process specifically over 3D substrates. In this work, we have studied the effect of a moderate nanoplatelets agglomeration, by tuning their surfaces with a polyelectrolyte multilayer following a Layer-by-Layer (LbL) methodology and fixing the electric conditions of the EPD process. Overcoming the destructive effects of the full agglomeration of nanoplatelets, NiO films with a stable and extremely open macroporous structure were processed to coat Ni foams, improving the capacitive performance of pseudocapacitors leading to values of specific capacitances of 650 F/g. Results collected in this work also evidence that an efficient ordering and orientation of nanoplatelets in EPD mainly depends on tuning the suspension parameters (solid contents, conductivity, electrophoretic mobility, etc.) to avoid the massive flux and interactions among interparticles and electro-hydrodynamic forces, as well as the interference of collateral electrode phenomena.