The exploration of cost-effective and sustainable biomass-derived carbon materials as electrodes for energy conversion and storage has gained extensive attention in recent research studies. However, the selection of the biomass and the electrochemical performance regulation of the derived biochar, as well as their interrelationship still remain challenging for practical application. Herein, corn wastes with high carbon content (>40%), corn cob and corn silk, were selected as precursors for the preparation of high value-added and high yield carbon materials via a modified synthetic process. Uniquely, this work put emphasis on the theoretical and experimental investigations of how the biomass properties influence the composition and nanostructure regulation, the electrolyte ion adsorption free energy, and the electrical conductivity of the derived carbon materials as well as their electrochemical performance optimization. Owing to the favorable specific surface area, the hierarchical porous structure, and the diverse elemental distribution, corn cob and corn silk derived carbon materials (CBC and SBC) present great potential as promising electrodes for alkaline aqueous zinc batteries and supercapacitors. The assembled CBC//Zn and SBC//Zn zinc batteries deliver high energy densities of 63.0 Wh kg⁻¹ and 39.1 Wh kg⁻¹ at a power density of 575 W kg⁻¹, with excellent cycling performance of 91.1% and 84.3% capacitance retention after 10,000 cycles. As for the assembled symmetric supercapacitors, high energy densities of 14.9 Wh kg⁻¹ and 13.6 Wh kg⁻¹, and superior long-term cycling stability of 99.3% and 96.6% capacitance retention after 20,000 cycles could be achieved. This study highlights the advantages of utilizing corn cob and corn silk as carbon sources on the designed synthesis of carbon electrodes, and presents a meaningful perspective in the investigation of biomass-derived carbon materials and their potential applications in rechargeable devices.

With the rapid development of modern society, the efficient development and utilization of new energy have become more and more important. The development of high-performance energy storage and conversion devices has a decisive impact on the sustainable and efficient use of energy. In the foreseeable future, the exploration of high-quality functional materials for energy storage and conversion will continue to be the main goal pursued by the scientific and application fields. Metal organic frameworks (MOFs) have the merits of adjustable porosity and a stable structure. Moreover, the metal elements in the MOFs could play a role as active sites during the electrochemical process. Thus, various kinds of MOFs and their derivatives have been prepared and used as functional materials for energy storage and conversion. In this work, the applications and potentials of cobalt-based MOFs (Co-MOFs) and their derivatives in supercapacitors, advanced batteries, and electrochemical catalysts have been reviewed and summarized. The electrochemical properties, energy storage and conversion mechanisms, and the effects on performance were described in depth. A large number of Co-MOFs with unique structures, as well as numerous Co-MOF derivatives and composites, have been developed, and excellent application performance has been achieved, which have already become some of the most advantageous functional materials in the energy storage and conversion field. In addition, the current research status, difficulties, and prospects of Co-based MOFs and their derivatives as energy storage and conversion functional materials were comprehensively summarized at the end of this study.

Copper-based compounds have attracted increasing attention as electrode materials for rechargeable devices, but their poor conductivity and insufficient stability inhibit their further development. Herein, an effective method has been proposed to improve the electrochemical properties of the copper-based electrodes by coating carbon materials and generating unique micro/nanostructures. The prepared Cu₂S/Cu₇S₄/NC with hierarchical hollow structure possesses excellent electrochemical performance, attributing to the composition and structure optimization. The superior charge storage performance has been assessed by theoretical and experimental research. Specifically, the Cu₂S/Cu₇S₄/NC exhibits remarkably higher electrical conductivity and lower adsorption-free energy for O* and OH* than those of Cu₂O. Moreover, the Cu₂S/Cu₇S₄/NC delivers a high specific capacitance of 1261.3 F·g^-1 at the current density of 1 A·g^-1 and also has great rate performance at higher current densities, which are much better than those of the Cu₂O nanocubes. In addition, the assembled hybrid supercapacitor using Cu₂S/Cu₇S₄/NC as the anode exhibits great energy density, power density, and cycling stability. This study has proposed a novel and feasible method for the synthesis of high-performance copper-based electrodes and their electrochemical performance regulation, which is of great significance for the advancement of high-quality electrode materials and rechargeable devices.