Electrochemical performance of Na0.6[Li0.2Ni0.2Mn0.6]O2 cathodes with high-working average voltage for Na-ion batteries

Abstract

Na_0.6[Li_0.2Ni_0.2Mn_0.6]O₂ is synthesized by a self-combustion reaction (SCR) and studied for the first time as a cathode material for Na-ion batteries. The Na_0.6[Li_0.2Ni_0.2Mn_0.6]O₂ cathode presents remarkable high rate capability and prolonged stability under galvanostatic cycling. A detailed analysis of X-ray diffraction (XRD) patterns at various states of cycling reveals that the excellent structural stability is due to a primarily solid-solution sodiation/desodiation mechanism of the material during cycling. Moreover, a meaningful comparison with Na_0.6MnO₂ and Na_0.6[Li_0.2Mn_0.8]O₂ reveals that the Na_0.6[Li_0.2Ni_0.2Mn_0.6]O₂ cathode achieves a very high working-average voltage that outperforms most of the lithium-doped manganese-oxide cathodes published to date.