Nanocellulose-Mediated Transition of Lithium-Rich Pseudo-Quaternary Metal Oxide Nanoparticles into Lithium Nickel Cobalt Manganese Oxide (NCM) Nanostructures

Abstract

We report the syntheses of various compounds within the pseudo-quaternary system of the type LiwNixCoyMnzOδ (δ≤1) (pre-NCMs). Four different compositions of this compound were realized as ultrasmall crystalline nanoparticles of 1–4 nm diameter using low-temperature solvothermal reaction conditions in tert-butanol at only 170 °C. All of the pre-NCMs crystallize in the rock-salt structure and their lithium content is between 20% and 30% with respect to the complete metal content. By adjusting the lithium content to 105% stoichiometry in the solvothermal reaction, the pre-NCMs can easily react to the respective Li(NixCoyMnz)O2 (NCM) nanoparticles. Furthermore, nanosized desert-rose structured NCMs were obtained after addition of nanocellulose during the synthesis. By using the mixed metal monoxides as precursor for the NCMs, cation mixing between lithium and nickel is favored and gets more pronounced with increasing nickel content. The cation mixing effect compromises good electrochemical capacity retention, but the desert-rose structure nevertheless enables enhanced stability at high power conditions, especially for NCM333.