Sodium ion batteries (SIBs) are one of the most potential alternative rechargeable batteries because of their low cost, high energy density, high thermal stability, and good structure stability. The cathode materials play a crucial role in the cycling life and safety of SIBs. Among reported cathode candidates, Na 3 V 2 (PO 4) 3 (NVP), a representative electrode material for sodium super ion conductor, has good application prospects due to its good structural stability, high ion conductivity and high platform voltage (∼3.4 V). However, its practical applications are still restricted by comparatively low electronic conductivity. In this review, recent progresses of Na 3 V 2 (PO 4) 3 are well summarized and discussed, including preparation and modification methods, electrochemical properties. Meanwhile, the future research and further development of Na 3 V 2 (PO 4) 3 cathode are also discussed.

Li2ZnTi2.9Cr0.1O8 and Li2ZnTi3O8 were synthesized by the liquid phase method and then studied comparatively using X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), galvanostatic charge–discharge testing, cyclic stability testing, rate performance testing, and electrochemical impedance spectroscopy (EIS). The results showed that Cr-doped Li2ZnTi3O8 exhibited much improved cycle performance and rate performance compared with Li2ZnTi3O8. Li2ZnTi2.9Cr0.1O8 exhibited a discharge ability of 156.7 and 107.5 mA h g−1 at current densities of 2 and 5 A g−1, respectively. In addition, even at a current density of 1 A g−1, a reversible capacity of 162.2 mA h g−1 was maintained after 200 cycles. The improved electrochemical properties of Li2ZnTi2.9Cr0.1O8 are due to its increased electrical conductivity.

(A and B) CV curves of (A) Li2ZnTi3O8/C and (B) Li1.9K0.1ZnTi3O8/C, (C) Initial charge–discharge curves and (D) cycling capacity and (E) rate performances of Li2ZnTi3O8/C and Li1.9K0.1ZnTi3O8/C. (F) The composition of the CR2032 cell.

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