Overview of the oxygen vacancy effect in bimetallic spinel and perovskite oxide electrode materials for high-performance supercapacitors

Bimetallic spinel and perovskite metal oxide materials are advanced electrode materials for supercapacitor (SC) applications because of their low-cost, distinct crystal structures, eco-friendly nature, and high conductivity. However, they suffer from the disadvantages of poor ion-diffusion kinetics and pulverization issues during cyclability tests. Along with a deeper understanding of redox chemistry, the role of oxygen vacancies (OVs) in electrode materials to support the reaction kinetics for excellence in SCs must be clarified. In this review, we highlight for the first time the importance of OVs and summarize various design strategies for the preparation of advanced bimetallic spinel oxides and perovskites with improved electrochemical performances for SC applications. With new insights, we envision that the SC research community would endeavor to utilize the benefits of OVs effectively for the development of high-performance SCs.

The influence of surface area, porous structure, and surface state on the supercapacitor performance of titanium oxynitride: implications for a nanostructuring strategy

Underlying factors governing the capacitance and stability of titanium oxynitride are revealed.

Applications of hierarchically structured porous materials from energy storage and conversion, catalysis, photocatalysis, adsorption, separation, and sensing to biomedicine

A comprehensive review of the recent progress in the applications of hierarchically structured porous materials is given.

Carbon quantum dots/nickel oxide (CQDs/NiO) nanorods with high capacitance for supercapacitors

Novel CQDs/NiO nanorods have been prepared via a facile complexation method followed by a thermal treatment process and used as electroactive materials for supercapacitors, which deliver a high specific capacitance of 1858 F g⁻¹ at 1 A g⁻¹.

Nitrogen-Doped Carbon Nanocoil Array Integrated on Carbon Nanofiber Paper for Supercapacitor Electrodes

Integrating a nanostructured carbon array on a conductive substrate remains a challenging task that presently relies primarily on high-vacuum deposition technology. To overcome the problems associated with current vacuum techniques, we demonstrate the formation of an N-doped carbon array by pyrolysis of a polymer array that was electrochemically grown on carbon fiber paper. The resulting carbon array was investigated for use as a supercapacitor electrode. In-depth surface characterization results revealed that the microtextural properties, surface functionalities, and degree of nitrogen incorporated into the N-doped carbon array can be delicately controlled by manipulating carbonization temperatures. Furthermore, electrochemical measurements showed that subtle changes in these physical properties resulted in significant changes in the capacitive behavior of the N-doped carbon array. Pore structures and nitrogen/oxygen functional groups, which are favorable for charge storage, were formed at low carbonization temperatures. This result showed the importance of having a comprehensive understanding of how the surface characteristics of carbon affect its capacitive performance. When utilized as a substrate in a pseudocapacitive electrode material, the N-doped carbon array maximizes capacitive performance by simultaneously achieving high gravimetric and areal capacitances due to its large surface area and high electrical conductivity.

Synthesis of carbon fiber@nickel oxide nanosheet core–shells for high-performance supercapacitors

We report on the design and synthesis of CFs@NiO-NSs by growing nickel oxide nanosheets (NiO-NSs) on carbon fibers (CFs), and find that the system shows a more enhanced electrochemical performance.

One-dimensional cadmium hydroxide nanowires towards electrochemical supercapacitor

Room-temperature synthesis of Cd(OH)₂ thin film consisting of high-surface-area nanowires. Device-grade development as a symmetric supercapacitor.