Polyanion-type cathode materials for sodium-ion batteries

Abstract

This review summarizes the recent progress and remaining challenges of polyanion-type cathodes, providing guidelines towards high-performance cathodes for sodium ion batteries.

Challenges of today for Na-based batteries of the future: From materials to cell metrics

“…Besides layered oxides, polyanionic compounds are attractive as positive electrode materials for NIBs due to their operating voltage, which can be widely tuned by changing the nature of the involved redox couple as well as the composition and the structure of the anionic framework (see Table S2) [45]. Indeed, the strength of the X-O (X = P, S, Si, C) bonding in the anionic framework has an influence on the covalency of the M − O bond (and, therefore, on the position of the antibonding energy levels) resulting in a larger operating voltage vs Na for a given redox couple than for the bare oxide.…”

“…(For interpretation of the references to colour in this figure legend, the reader is referred to the Web version of this article.) agglomeration during long-term electrochemical cycling at high rates [56].…”

Phase Engineering of Nanomaterials for Clean Energy and Catalytic Applications

“…Take NaFePO 4 as a typical example, the thermodynamically stable maricite phase of NaFePO 4 is nearly electrochemically inactive for SIBs because the maricite phase does not possess the Na + diffusion pathway. [39,40] However, after the maricite NaFePO 4 NPs were first charged to 4.5 V (vs Na/Na + ) and kept for 5 h to extract all Na + ions, the overextraction of Na + ions induced a structural distortion of FePO 4 , leading to the phase transformation from maricite to amorphous. Even after the Na + ions were reinserted into FePO 4 , the amorphous phase remained.…”

Storage performance of Mg2+ substituted NaMnPO4 with an olivine structure

“…Sodium manganese phospho-olivine, NaMnPO 4 , is considered to be an attractive alternative to the conventional iron-based electrode material, NaFePO 4 , for sodium ion batteries. 1,2 This is a consequence from the high redox potential of the Mn 2+ / Mn 3+ ionic pair, thus reaching higher energy density. 1,3 Irrespective of this advantage, the studies on the electrochemical activity of NaMnPO 4 remain relatively fragmentary in comparison with that of NaFePO 4 .…”