Microwave calcination as a novel route to prepare high performance Mg-doped Na2/3Ni1/3Mn2/3O2 cathodes for sodium-ion batteries
M.R.D. Bomio, Pedro Lavela, R.L. Tranquilin, F.V. Motta, José L. Tirado
Abstract
Microwave calcination is proposed as an alternative to conventional heating in an electric furnace to provide high performance electrodes for sodium-ion batteries. The short annealing time was compatible with the preparation of pure and highly crystalline Mg-doped Na2/3Ni1/3Mn2/3O2 samples. The kinetic response of the electrode samples at three distinct stages of the galvanostatic cycling evidenced the better electrochemical performance of the microwave calcined samples as compared with a reference sample prepared by conventional heating procedures. The higher crystallite size and lower microstrains observed by microwave annealing is crucial to provide a positive electrode with less resistive behavior at high rates, higher Na+ diffusion coefficient, and lower cell internal resistance.