Exfoliating transition metal oxide lithium intercalation particles having lithium ions intercalated between transition metal oxide nanosheets includes electrochemically oxidizing a transition metal in first transition metal oxide lithium intercalation particles from a first oxidation state to a second oxidation state, inserting first cations having a radius exceeding the radius of a lithium ion into the vacancies, reducing the transition metal from the second oxidation state to the first oxidation state, and exfoliating the transition metal oxide nanosheets from the second transition metal oxide lithium intercalation particles to yield dispersed transition metal oxide nanosheets comprising the transition metal in the first oxidation state and oxygen. The dispersed transition metal oxide nanosheets can be reassembled to yield a material suitable for a lithium-ion battery cathode. Metal oxide sodium intercalation particles can be similarly exfoliated and reassembled to yield a material suitable for a sodium-ion battery cathode.