P3-type layered Na0.26Co1−xMnxO2 cathode induced by Mn doping for high-performance sodium-ion batteries

•A P3 layered Na0.26Co0.48Mn0.52O2 is successfully synthesized by a modified solvent-thermal with calcination.•The Mn doping tunes the structure from P2 to P3 with a wider interlayer spacing showing an ultra-high rate performance.•Electrochemical tests confirm the enhancement of capacity is expected to arise from the Mn doping.•The sodium-ion full-cell constructed from NCMO-1 cathode and hard carbon anode provides an attractive energy density. [Display omitted] Layered P-type structures are integral to most competitive cathodes for sodium-ion batteries (SIBs). However, the performance of P2-type cobalt-based layered materials is unsatisfactory owing to a low initial discharge capacity caused by Na deficiency. Here, Mn-doped NaxCoO2 with a P3 structure is synthesized by using a modified solvent-thermal method with calcination. A structural analysis shows that partial Mn doping can effectively control P3 phase formation and increase d-layer spacing, thereby improving the diffusion of Na+. In addition, enhanced electrochemical performance is observed in optimized P3-type Na0.26Co0.48Mn0.52O2(NCMO-1), which exhibits a reversible specific capacity of 64 mAh g−1 at 3 A g−1 and a good capacity retention of 58% after 500 cycles. Furthermore, the Na-ion full cell constructed with an NCMO-1 cathode and a hard carbon anode yields a competitive energy density of 175.9 Wh kg−1 at 0.4 A g−1 with excellent cycle stability. Thus, this work provides a new viewpoint on the development of P3 structural materials with higher electrochemical performance for SIBs.