Engineering sodium-rich manganese oxide with robust tunnel structure for high-performance sodium-ion battery cathode application

Layer sodium-based manganese oxides are one of potentially applicable sodium-ion battery (SIB) cathode materials mainly because of their lower cost and relatively reversible Na+ intercalation/extraction attributes. However, unavoidable Jahn-Teller effect arisen from manganese redox reactions causes serious lattice distortion, leading to distinct capacity fade. NaxMnO2 (x < 0.44) with tunnel structure shows good tolerance of deformation, but its intrinsically low sodium compositions determine its limited capacity. Herein, we report a novel sodium-rich tunnel-type Na0.6MnO2 material fancily prepared with the guidance of cetyltrimethylammonium bromide (CTAB) surfactant. Due to the robust structure and high sodium contents, the tailored CTAB-Na0.6MnO2 exhibits outstanding cycling durability with high discharge capacity. The fast Na+ diffusion kinetics and the restorable framework during charge/discharge cycling are further approved by galvanostatic intermittent titration technique (GITT) and ex situ x-ray diffraction (XRD) techniques. The sodium-rich tunnel-structured manganese oxide provides a new perspective of engineering high-performance SIB cathode materials.