Novel NASICON‐Type Na‐V‐Mn‐Ni‐Containing Cathodes for High‐Rate and Long‐Life SIBs

Abstract

Partial substitution of V by other transition metals in Na3V2(PO4)3 (NVP) can improve the electrochemical performance of NVP as a cathode for sodium–ion batteries (SIBs). Herein, phosphate Na–V–Mn–Ni–containing composites based on NASICON (Natrium Super Ionic Conductor)–type structure have been fabricated by sol–gel method. The synchrotron–based X–ray study, X–ray diffraction (XRD), and X–ray photoelectron spectroscopy (XPS) studies show that manganese/nickel combinations successfully substitute the vanadium in its site within certain limits. Among the received samples, composite based on Na3.83V1.17Mn0.58Ni0.25(PO4)3 (VMN–0.5, 108.1 mAh g−1 at 0.2 C) shows the highest electrochemical ability. The cyclic voltammetry, galvanostatic intermittent titration technique, in situ XRD, ex situ XPS, and bond valence site energy calculations exhibit the kinetic properties and the sodium storage mechanism of VMN–0.5. Moreover, VMN–0.5 electrode also exhibits excellent electrochemical performance in quasi–solid–state sodium metal batteries with PVDF–HFP quasi‐solid electrolyte membranes. The presented work analyzes the advantages of VMN–0.5 and the nature of the substituted metal in relation to the electrochemical properties of the NASICON–type structure, which will facilitate further commercialization of SIBs.

Doping modification of sodium superionic conductor Na3V2(PO4)3 cathodes for sodium-ion batteries: a mini-review

“…Na + diffusion occurs through channels between adjacent PO 4 tetrahedra and gaps between the PO 4 tetrahedra and VO 6 octahedra. 84,92 Therefore, decreasing the size of both the PO 4 tetrahedra and VO 6 octahedra can widen the Na + diffusion channels. 85 Doping with Ni causes the average length of both V-O and Na-O bonds to decrease, which widens the Na + diffusion channels.…”