The Development of Vanadyl Phosphate Cathode Materials for Energy Storage Systems: A Review

Abstract

Various cathode materials have been proposed for high‐performance rechargeable batteries. Vanadyl phosphate is an important member of the polyanion cathode family. VOPO4 has seven known crystal polymorphs with tunneled or layered frameworks, which allow facile cation (de)intercalations. Two‐electron transfer per formula unit can be realized by using VV/VIV and VIV/VIII redox couples. The electrochemical performance is closely related to the structures of VOPO4 and the types of inserted cations. This Review outlines the crystal structures of VOPO4 polymorphs and their lithiated phases. The research progress of vanadyl phosphate cathode materials for different energy storage systems, including lithium‐ion batteries, sodium‐ion batteries, potassium‐ion batteries, multivalent batteries, and supercapacitors, as well as the related mechanism investigations are summarized. It is hoped that this Review will help with future directions of using vanadyl phosphate materials for energy storage.

Towards Reversible High-Voltage Multi-Electron Reactions in Alkali-Ion Batteries Using Vanadium Phosphate Positive Electrode Materials

“…Beyond their fascinating electrochemical properties, vanadium phosphate materials possess very interesting catalytic and magnetic properties. The relation between structures and these properties was already reviewed by Raveau's group 20 years ago [15] and despite the existence of several reviews on polyanionic structures in Li and Na-ion batteries [16][17][18][19], or even specific to vanadyl phosphates (i.e., A x (VO)PO 4 ) [20,21], none of them focused on the relation between electrochemical properties and crystallographic structure in vanadium phosphates. Therefore, this article aims at clarifying this relation in order to unveil the structural features that dictate the redox voltage in such compounds.…”

Recent Progress and Prospects of Layered Cathode Materials for Potassium‐ion Batteries

“…VOPO 4 polymorphs contain at least 7 phases (α I , α II , β, ε, γ, δ, and ω), in which α I ‐ and α II ‐VOPO 4 contain [VOPO 4 ] ∞ chains consisting of corner‐shared VO 5 pentahedral and PO 4 tetrahedral and form a layered structure. [ 85 ] Li + insertion behaviors in various VOPO 4 polymorphs have been investigated, [ 86,87 ] yet few of them are electrochemically active for Na + and K + . Probably, the relatively narrow interlayer spacings and interstitial sites are difficult for the large Na + /K + ion insertion.…”

Polymorphic Purity and Structural Charge–Discharge Evolution of β-LiVOPO4 Cathodes

“…The compound exists in different polymorphs with trigonal (α 1 ), orthorhombic (β), or triclinic (ε/α) symmetry. 14 These polymorphs are all capable of both Li-ion intercalation and deintercalation, with the β-VOPO 4 exhibiting the lowest energy barrier for one-dimensional (1D) Li-ion diffusion and being the most stable host framework. 15 β-VOPO 4 was first prepared by Lii et al 16 in 1991, and the Li-ion intercalation properties were investigated in 1999 by Gaubicher et al 17 Other synthesis methods for the preparation of β-LiVOPO 4 were not discovered until 2003, where two groups, Barker et al 9 and Azmi et al, 18 obtained β-LiVOPO 4 via a carbothermal reaction and a sol−gel synthesis with a postsintering step, respectively.…”