Abstract
Electrochemical Mg-Cu displacement is recognized as the prominent capacity-contribution reaction in copper-based chalcogenide cathodes. However, such one-sided mechanism experiences low discharge voltage plateau and thus restricts the exploitation of high-energy magnesium batteries. Herein, a synergetic cationic-anionic redox chemistry mechanism is revealed in anion-rich copper selenide (CuSe2) cathode for high-energy magnesium batteries. Ex-situ spectroscopic characterization and DFT calculations demonstrate the mechanism with high-voltage Se-Cl anionic redox chemistry and low-voltage cationic Mg-Cu replacement reaction. A series of copper selenides with controllable anion content are fabricated by phase engineering strategy via regulating the Se source concentration during selenization. The anion-rich CuSe2 cathode shows both superior anionic and cationic redox reactions for Mg2+ storage kinetics with considerable capacity of 440.6 mAh g–1 and high energy density of 439.4 Wh kg–1. Based on the outstanding reaction kinetics, the CuSe2 cathode also delivers remarkable rate capability with 169 mAh g–1 at 2.0 A g–1 and cycling life for 1500 cycles. Theoretical investigation suggests that the anion-rich phase can show the most effective adsorption of Mg2+ and Cl– and the highest conductivity. This work unveils a brand-new anionic-cationic redox chemistry mechanism and provides a high-efficiency strategy for fabricating anion-rich copper selenides toward high-energy rechargeable magnesium batteries.
Original language | English |
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Article number | 104304 |
Journal | Energy Storage Materials |
Volume | 79 |
DOIs | |
Publication status | Published - Jun 2025 |
Keywords
- Anion-rich copper selenides
- High-energy cathode
- Rechargeable magnesium batteries
- Se-Cl anionic redox