Lithium-Rich Transition Metal Oxides as Positive Electrode Materials in Lithium-Ion Batteries

Abstract

Lithium-rich transition metal oxides are candidates for the next-generation lithium-ion battery positive electrode materials. They have a much higher first charge and low-rate cycling capacity compared to non-lithium rich transition metal oxides. In this thesis, the preparation of spherical and dense transition metal oxide was studied. The morphology and tap-density of the hydroxide precursor was found to be dependent on the coprecipitation reaction pH. The coprecipitation reaction in the presence of aqueous ammonia was studied by analyzing the relevant chemical equilibria. The electrochemistry of lithium-rich oxides was studied as a function of particle size. The apparent oxygen diffusion coefficients were estimated using the Atlung graph method and were determined to be several orders of magnitude lower than normal lithium deintercalation. Isothermal mass calorimetry measurements showed evidence of a local Jahn-Teller distortion in the MnO6 units during discharge. Other studies of the lithium-rich oxides were also carried out.