Copper Vanadium Oxide Yolk-Shell Microspheres with Excellent Capacitance and Cycling Performance for Electrochromic...

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Vanadium pentoxide (V2O5) shows promise for electrochromic supercapacitors but suffers from low conductivity and poor cyclability.
• These limitations hinder the practical application of V2O5 in energy storage devices.

Purpose of the Study:

• To enhance the electrochemical performance and long-term stability of V2O5-based materials for electrochromic supercapacitors.
• To develop a novel composite material by doping V2O5 with copper and integrating it with Na2V6O16·3H2O nanowires.

Main Methods:

• Synthesis of copper vanadium oxide yolk-shell microspheres (CVO) via solvent heat treatment and annealing.
• Formation of a sphere-wire network structure using CVO and Na2V6O16·3H2O nanowires (NVO) to create CVO/NVO composites.
• Assembly and testing of fully inorganic solid-state electrochromic supercapacitors (ECSCs) using the CVO/NVO composite.

Main Results:

• The CVO/NVO composite demonstrated a high specific capacitance of 39.2 mF cm⁻² with 84% retention after 7500 cycles.
• The assembled ECSCs exhibited a distinct color change (ΔE* = 37) and superior energy storage (18.4 mF·cm⁻²).
• The devices showed excellent cycling stability, retaining 89% capacitance after 10,000 cycles.

Conclusions:

• The developed CVO/NVO composite material significantly enhances the conductivity, capacitance, and cyclic stability of V2O5.
• The unique sphere-wire network structure optimizes redox sites and substrate bonding, leading to superior device performance.
• This work presents a promising pathway for advanced V2O5-based electrochromic energy storage devices.