A novel reed‐leaves like aluminum‐doped manganese oxide presetting sodium‐ion constructed by coprecipitation method for high electrochemical performance sodium‐ion battery

In this paper, Al-doped manganese oxide with presetting sodium-ion (NaxMnyAlzO2) is synthesized by a facile coprecipitation method and combines with Na3V2(PO4)3 cathode active materials for sodium-ion battery in order to optimize the electrochemical performances. During the coprecipitation, a stable NaxMnyAlzO2 polynary metal oxide with Mn and Al molar ratio to 3:1 shows a special micromorphology similar to that of reed leaves, which makes it have a more ideal electrochemical specific surface area and ample mass transfer channels for rapid sodium-ion insertion and desorption. Electrochemical test indicates that reed-leaves like NaxMnyAlzO2 polynary metal oxides as active material for sodium-ion capacitor exhibit a very excellent reversibility and low electrochemical (Rct = 434 Ω) and concentration polarization (DNa+ = 2.2728 × 10−11 cm2 s−1). Specific discharge capacity can achieve to 73.76 F g−1 at 100 mA g−1 current density corresponding to 368.8 m2 g−1 electrochemical specific surface area. After 200 cycles, the capacity retention rate can be maintained at 81.81%. In addition, reed-leaves like NaxMnyAlzO2 polynary metal oxide playing a good depolarization role combined with Na3V2(PO4)3 active materials in the mass ratio to 7:3 can bring about the most excellent electrochemical performances.