In situ probing conductivity and deformation of single Ni-rich Li[Ni0.885Co0.1Al0.015]O2 and Li[Ni0.885Co0.1V0.015]O2 nanoparticles by scanning probe microscopy

Abstract

Li[Ni0.885Co0.1V0.015]O2 (NCV), Li[Ni0.9Co0.1]O2 (NC), and Li[Ni0.885Co0.1Al0.015]O2 (NCA) nanoparticles are synthesized by means of oxalic acid co-precipitation with subsequent calcination. The evolution of Li-ion diffusion and deformation of both NCV and NCA under an external electric field are characterized by means of conductive atomic force microscopy and electrochemical strain microscopy. Macroscopic electrochemical characterization reveals that the Li-ion diffusivity in NCA is greater than that in NCV, and the undesirable irreversible H2–H3 phase transition occurs more readily in NCV than in NCA. The scanning probe microscopy results corroborate well with the macroscopic electrochemical measurements, which tell that vanadium and aluminum substitution can accelerate Li+ diffusion kinetics and enhance the reversibility of the H2–H3 phase transformation during the electrochemical process in varying degrees.