Preparation of Vanadium Pentoxide Materials and Their Supercapacitor Performance

The large-scale development of renewable energy is still advancing, and the efficient and stable electrochemical energy storage technology has been pushed to a more important position, which has gradually become an indispensable key pillar in energy transformation. Supercapacitors rely on high power density and long cycle life, so there has been a lot of attention in the field of energy storage ; but it has a limited energy density, which would restrict a wider range of applications. Based on this background, this paper takes vanadium pentoxide (V 2 O 5 )-based electrode materials as the core. Firstly, the energy storage mechanism of supercapacitors is systematically reviewed, and the preparation methods and morphology control strategies of V 2 O 5 and its composites are also reviewed. Looking further down, pure-phase V 2 O 5 has the disadvantages of poor conductivity and unstable structure, which cannot be ignored. In view of them, this paper summarizes the modification methods such as carbon compositing, porous structure construction, heteroatom doping, and ternary synergistic effect, and also summarizes the mechanism of these methods to improve electrochemical performance. In addition, this study further examines the inherent limitations of the above modification strategies in practical applications, that is, after putting these strategies into real scenarios, what are the limitations.Among these limitations, there are not only the trade-off of carbon content, but also the lattice distortion caused by doping, and the volumetric capacitance loss caused by porous structure. Focusing on these problems, this work first distinguishes the intrinsic pseudocapacitance from the diffusion-controlled energy storage mechanism, clarifies the role of oxygen vacancies in regulating ion diffusion kinetics, and reviews the differences in the existing literature on dopant selection, optimal doping concentration and vanadium dissolution suppression mechanism. In practice, low-loading thin-film electrodes in the laboratory often have excellent performance. However, once the actual devices based on high-loading thick electrodes are corresponding, the stringent requirements are completely different, and the significant gap between the two is thus highlighted. On the basis of these analyses, this paper proposes a feasible and targeted research direction. The purpose is to provide practical guidance for the design of high-energy-density and long-cycle-life supercapacitor electrodes suitable for practical applications.