Concomitant mitigation of VO${}_6$ octahedron distortion and band broadening in V${}_2$O${}_3$ for high-performing flexible supercapacitors

Vanadium trioxide (V${}_2$O${}_3$) has emerged as one of the promising candidates for fiber-shaped supercapacitors. However, irreversible redox behavior during prolonged cycling process has been commonly reported due to the intrinsically distorted VO${}_6$ octahedron in V${}_2$O${}_3$, which inevitably compromises its electrochemical capacitance. Herein, a strategy to simultaneously mitigate the distortion in VO${}_6$ octahedron and optimization of electronic structure in V${}_2$O${}_3$ is proposed by studying a Mo-doped V${}_2$O${}_3$ modified stainless steel wire (Mo-V${}_2$O${}_3$@SSW). The introduction of Mo dopants effectively tunes the V-O local environment, resulting in a substantial alleviation of the distortion in VO${}_6$ octahedron. The as-prepared Mo-V${}_2$O${}_3$ with a more regular VO${}_6$ octahedron exhibits highly reversible redox behavior, with negligible structural change after 10 000 cycles. Moreover, it is found that doping Mo into V${}_2$O${}_3$ leads to V 3d band broadening, which generates more electronic states around Fermi level, thereby significantly accelerating the electron transfer during redox processes. Consequently, Mo-V${}_2$O${}_3$@SSW attains a capacitance of 774.4 mF cm${}^{-2}$ at 0.4 mA cm${}^{-2}$, with a capacitance retention of 85.49% after 10 000 cycles. And the integration of Mo-V${}_2$O${}_3$@SSW supercapacitors, further showcases its strong applicability in wearable technologies. The comprehensive understanding of the structural-activity/stability relationship in this study offers a novel paradigm for developing flexible high-performing supercapacitors. (© 2024 Wiley‐VCH GmbH)