Copper Tetraselenophosphate Cathode for Rechargeable Magnesium Batteries: A Redox-Active Polyatomic Anion Strategy to Design the Cathode Material

Abstract

Rechargeable magnesium batteries attract interest as advantageous energy-storage devices, but the application is being hampered by the deficiency of suitable cathodes. The traditional method to weaken the interaction between bivalent Mg 2+ cations and the cathode material is to increase the anion radius, but excessive expansion of the anion would lead to a decrease of the theoretical capacity and offset the performance improvement. Herein, a new strategy using a redox-active polyatomic anion is developed in terms of copper tetraselenophosphate (Cu 3 PSe 4 ) fabricated by the PSe 4 3− anion. The covalent P−Se bond facilitates the negative charge delocalization of the PSe 4 3− anion and weakens the interaction with Mg 2+ cations, which result in rapid solid-phase Mg 2+ diffusion kinetics. The PSe 43− anion also provides extra capacities by reversible valence state change of the P element. Cu 3 PSe 4 delivers a high Mg-storage capacity of 225 mAh g −1 at 50 mA g −1 and a superior rate performance of 62 mAh g −1 at 5000 mA g −1 , as well as a stable cyclability of 500 cycles. The redox-active polyatomic anion strategy herein opens a new avenue for the exploration of magnesium battery cathodes with a comprehensive consideration of kinetic performance and theoretical capacity.

Copper Selenophosphate, Cu3PSe4, Nanoparticle Synthesis: Octadecane Is the Key to a Simplified, Atom-Economical Reaction

“…Additionally, X-ray photoelectron spectroscopy (XPS) of the carbon (C) and nitrogen (N) 1s regions (Figure S19) is representative of HDA binding environments according to previous literature reports. ,, Of note, the Cu and P 2p binding region (Figure A and B) demonstrates the characteristic Cu 3– x P environments, ,− while the satellite Cu­(II) peak (Figure B) and P–O peak at 134 eV likely corresponds to surface oxides. − , Finally, Cu 3 PSe 4 was characterized with XPS for Cu, P, Se, and C bonding environments (Figure S20). The core bonding environments (Cu, P and Se) were consistent with previous reports of Cu 3 PSe 4 and Cu 3 PS 4 , − , whereas the C region had similar peaks to Cu 3– x P NPs but a decrease in the C-NH 2 environment (Figure S20D). In summary, the spectroscopic evidence mentioned above confirms the sample purity and provides evidence for the nanoparticle surface composition, an important component of the net reaction stoichiometry.…”

“…Ternary chalcogenide nanoparticles (NPs) have recently gained considerable interest owing to their promising properties for technologically relevant applications, such as photovoltaics, − thermoelectrics, − and cathode materials. − Of particular interest is copper selenophosphate, Cu 3 PSe 4 , with its theoretical photovoltaic efficiency of 24% and earth abundant elemental composition. , Historical strategies targeting Cu 3 PSe 4 classically involve high temperature solid-state synthetic schemes from traditional elemental precursors (Table S1). ,,− A more recent solution-based synthesis of Cu 3 PSe 4 NPs from Lee et al achieved selenization of presynthesized Cu 3 P NPs in a one-pot heating method, using a 0.1 M Se 0 powder (Se 0 powder ) and 1-octadecene (1-ODE) solution . Their approach provided a promising tunable synthesis and potentially low-temperature device processing.…”

Mo3S13 Cluster-Based Cathodes for Rechargeable Magnesium Batteries: Reversible Magnesium Association/Dissociation at the Bridging Disulfur along with Sulfur–Sulfur Bond Break/Formation

“…The fundamental requirement of RMB cathode materials is the delocalization of negative charge. , Intrinsically, Ti, V, Mo, and W have valence orbital energy levels similar to S and Se, and the valence orbitals of S and Se are spatially relatively far from the nuclei . These two factors cause these two groups of elements to form chemical bonds with higher covalent proportions.…”

Copper selenide/amino hyperbranched polymer as an organic/inorganic hybrid composite cathode for rechargeable magnesium batteries

“…13,14 Meanwhile, conversion-type transition metal compounds can undergo multi-electron redox reactions, and many types of transition metal sulfides and selenides are reported to exhibit high Mg-storage capacities. 15–17…”