Microwave calcination as a novel route to prepare high performance Mg-doped Na2/3Ni1/3Mn2/3O2 cathodes for sodium-ion batteries

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 prepa-ration of pure and highly crystalline Mg-doped Na2/3Ni1/3Mn2/3O2 samples. The kinetic response of the elec-trode 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 conven-tional 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.

Automated summary

Microwave calcination is introduced as a substitute for conventional heating in electric furnace for the production of high-performance electrodes for sodium-ion batteries. The microwave annealing process allows for shorter annealing time and the preparation of pure and highly crystalline Mg-doped Na2/3Ni1/3Mn2/3O2 samples. The electrochemical performance of the microwave calcined samples is superior to a reference sample prepared by conventional heating methods, as evidenced by the kinetic response at different stages of galvanostatic cycling. This improvement can be attributed to the larger crystallite size and lower microstrains achieved through microwave annealing, which result in reduced resistive behavior, higher Na+ diffusion coefficient, and lower internal resistance of the positive electrode.