Electrochemical behaviour of solid lithium nickelate (LiNiO2) in an aqueous electrolyte system

Abstract: Lithium nickelate was synthesized by self-propagating high-temperature combustion. The electrochemical behaviour of the product was studied by cyclic voltammetry of microparticles immobilized on the surface of graphite electrodes. Whereas numerous previous studies have dealt with non-aqueous electrolyte solutions, here the behaviour of lithium nickelate in contact with aqueous electrolyte solutions was investigated. It could be shown that protons are intercalating upon reduction of the Ni(III) to Ni(II) and deintercalating upon oxidation. This insertion electrochemistry is chemically reversible. Within 1600 oxidation-reduction cycles, the response diminished only by about 10%. Scanning electron microscopy reveals a considerable recrystallization during the electrochemical cycles. Energy dispersive X-ray detection proved that no metal cations are intercalating. The electrochemical system is accessible only in very alkaline solutions as it shifts to more positive values with decreasing pH.