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 (approximate to 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.

Automated summary

CuSe nanoflakes designed through temperature-controlled crystal growth under microwave irradiation exhibit high reversible capacity, outstanding rate capability, and remarkable long-term cycling stability. The single-crystalline CuSe nanoflakes show relatively durable structural stability, attributed to the excellent pulverization-tolerance endowed by the multistep reversible conversion mechanism and single-crystalline feature. The preferentially-oriented (110) active plane facilitates electrochemical reactions for ensuring high specific capacity in the CuSe nanoflake cathode materials.