Local Structure Distortion in Mn, Zn Doped Cu₂V₂O₇: Supercapacitor Performance and Emergent Spin‐Phonon Coupling

Abstract Supercapacitors are rapidly gaining attention as next‐generation energy storage devices due to their superior power and energy densities. This study pioneers the investigation of Mn/Zn co‐doping in α‐Cu₂V₂O₇ (CVO) to enhance its performance as a supercapacitor electrode material. Structural and local Structural properties of Mn/Zn co‐doped CVO have been investigated through X‐ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), X‐ray Photoelectron Spectroscopy (XPS), and X‐ray Absorption Spectroscopy (XAS), revealing significant distortions that enhance supercapacitor performance. The optimized sample demonstrates a remarkable specific capacitance of 1950.95 Fg⁻¹, energy density of 97.54 Whkg⁻¹, and enhanced capacitive retention, attributed to the unique Cu coordination environment and improved charge transfer kinetics. Temperature‐dependent Raman spectroscopy unveils spin‐phonon coupling (SPC), particularly in VO₄ stretching modes, supported by magnetic measurements that shows a reduction in the Néel temperature and the emergence of zero field‐cooled (ZFC) exchange bias (EB). This work is the first to report the impact of local structure distortion on both supercapacitor performance and SPC in CVO, offering a novel strategy for developing high‐performance energy storage materials with spintronics potential. In addition, the assembled symmetric optimized supercapacitor shows a high energy density of 93.32 Whkg⁻¹ and excellent cycling stability. A prototype device incorporating the optimized CVO successfully powers eight commercial LED bulbs, demonstrating its practical application potential.