Synthesis of NaxMn0.54Ni0.13Fe0.13O2 with P2-type hexagonal phase as high-performance cathode materials for sodium-ion batteries

Abstract Na x Mn 0.54 Ni 0.13 Fe 0.13 O 2 ( x  = 0.46, 0.67) with P2-type hexagonal phase are synthesized via a sol-gel method as novel cathode materials for sodium-ion batteries. The followed characterization indicates the existence of coaxial hexagonal phase structure in two samples, among which Na 0.46 Mn 0.54 Ni 0.13 Fe 0.13 O 2 (NMNF-0.46) presents neat hexagonal nanosheets with a sharp edge, whereas Na 0.67 Mn 0.54 Ni 0.13 Fe 0.13 O 2 (NMNF-0.67) shows granular structure. Tested in sodium-ion batteries at the potential window of 2.0–4.2 V, the specific capacity of NMNF-0.46 is 132.5 mAh g −1 at a current density of 0.1C, and the capacity retention rate was 78% after 50 cycles. In contrast, the specific capacity of NMNF-0.67 is 99.5 mAh g −1 , but a high capacity retention rate of 86.8% is delivered. The promising electrochemical performance of Na x Mn 0.54 Ni 0.13 Fe 0.13 O 2 provides a meaningful reference for developing advanced cost-effective electrode materials for sodium-ion batteries.