Pulverization-Tolerant CuSe Nanoflakes with High (110) Planar Orientation for High-Performance Magnesium Storage

Copper chalcogenides are of great interest as conversion-type cathode materials due to their large specific capacity for rechargeable magnesium batteries, yet are subjected to severe capacity fading brought about by structure collapse in repetitive charge–discharge cycling. Herein, single-crystalline and (110) preferentially oriented CuSe nanoflakes are designed via a temperature-controlled crystal growth route under microwave irradiation. The as-prepared CuSe nanoflake cathode materials can present high reversible capacity (204 mAh g⁻¹ at 200 mA g⁻¹ current density), outstanding rate capability, and remarkable long-term cycling stability (≈0.095% capacity decay per cycle at 1 A g⁻¹ within 700 cycles). The multistep reversible conversion mechanism of the CuSe nanoflake cathode materials is evidenced by ex situ X-ray photoelectron spectroscopy and X-ray diffraction. Structure evolution investigation suggests that the single-crystalline CuSe nanoflakes can exhibit relatively durable structural stability. The desirable cycling stability can be ascribed to the excellent pulverization-tolerance of the CuSe nanoflake cathode materials endowed by the multistep reversible conversion mechanism and the single-crystalline feature. Furthermore, the preferentially-oriented (110) active plane is favorable for electrochemical reactions to ensure high specific capacity. This work can afford a crystal engineering strategy to fabricate high-performance conversion-type electrode materials for rechargeable magnesium batteries.