Theoretical Studies on the Quantum Capacitance of Two-Dimensional Electrode Materials for Supercapacitors

Review of Biomass-Derived Carbon Nanomaterials-From 0D to 3D-For Supercapacitor Applications

The transition to sustainable energy storage solutions has driven significant interest in supercapacitors, which offer high power density, rapid charge-discharge capabilities, and exceptional cycle stability. Biomass-derived carbon nanomaterials have emerged as compelling candidates for supercapacitor electrodes due to their renewable origins, environmental compatibility, and cost-effectiveness. This study explores recent advancements in tailoring structural properties, for example in preparation methods and activation, which are essential for efficient charge storage and rapid ion transport. Attention is given to the dimensional configurations-spanning 0D to 3D structures-and their impact on electrochemical behaviors. This review outlines the challenges faced in scaling up and optimizing these materials for practical applications, alongside an outlook on future research directions. By bridging the gap between material design and application demands, this work contributes to advancing sustainable supercapacitor technologies for a greener energy future.

Functionalised biphenylene and graphenylene: excellent choices for supercapacitor electrodes

Quantum capacitance (CQ) is a crucial parameter that reflects the energy storage capacity of supercapacitors. In this work, we extensively investigate the effect of vacancy induced defects on quantum capacitance of well studied biphenylene (BPN) and graphenylene (GPN) monolayers. Based on density functional theory (DFT), we have systematically studied the consequence of vacancies on structural stability, charge distribution, electronic band structure of pristine systems, and correlated this with the variation of quantum capacitance with applied voltage. The results demonstrate that insertion of a vacancy significantly improves the density of states (DOS) profile around the Fermi level for both structures, attributed to the localisation of charge carriers. This leads to higher CQ values for relatively lower potential, with the highest value of CQ being 221 μF cm-2 for defective BPN. Furthermore, we have calculated the density of surface charge for different voltages to evaluate the adaptability of particular materials as a cathode or anode. It is found that both pristine and defective BPN are more preferable as anode materials. It is noteworthy that GPN and its vacancy induced structure, stand-out as superior candidates for a symmetric supercapacitor in aqueous systems. This work will provide valuable insights to design BPN and GPN-based high performance electrode materials for electric double layer (EDL) supercapacitors.

Recent Advances and Strategies in MXene-Based Electrodes for Supercapacitors: Applications, Challenges and Future Prospects

With the growing demand for technologies to sustain high energy consumption, supercapacitors are gaining prominence as efficient energy storage solutions beyond conventional batteries. MXene-based electrodes have gained recognition as a promising material for supercapacitor applications because of their superior electrical conductivity, extensive surface area, and chemical stability. This review provides a comprehensive analysis of the recent progress and strategies in the development of MXene-based electrodes for supercapacitors. It covers various synthesis methods, characterization techniques, and performance parameters of these electrodes. The review also highlights the current challenges and limitations, including scalability and stability issues, and suggests potential solutions. The future outlooks and directions for further research in this field are also discussed, including the creation of new synthesis methods and the exploration of novel applications. The aim of the review is to offer a current and up-to-date understanding of the state-of-the-art in MXene-based electrodes for supercapacitors and to stimulate further research in the field.

Theoretical investigation of quantum capacitance of Co-doped α-MnO2 for supercapacitor applications using density functional theory

The rapid depletion of fossil fuels and ever-growing energy demand have led to a search for renewable clean energy sources. The storage of renewable energy calls for immediate attention to the fabrication of efficient energy storage devices like supercapacitors (SCs). As an electrode material for SCs, MnO2 has gained wide research interest because of its high theoretical capacitance, variable oxidation state, vast abundance, and low cost. However, the low electric conductivity of MnO2 limits its practical application. The conductivity of MnO2 can be enhanced by tuning the electronic states through substitution doping with cobalt. In the present work, first principles analysis based on density functional theory (DFT) has been used to examine the quantum capacitance (CQC) and surface charge (Q) of Co-doped MnO2. Doping enhanced the structural stability, electrical conductivity, potential window, and quantum capacitance of α-MnO2. The shortened band gap and localized states near the Fermi level improve the CQC of α-MnO2. For the narrow potential range (-0.4 to 0.4 V), the CQC is observed to increase with doping concentration. The highest CQC value at +0.4 V is observed to be 2412.59 μF cm-2 for Mn6Co2O16 (25% doping), five times higher than that of pristine MnO2 (471.18 μF cm-2). Mn6Co2O16 also exhibits better CQC and 'Q' at higher positive bias. Hence, it can be used as an anode material for asymmetric supercapacitors. All these results suggest better capacitive performance of Co-doped α-MnO2 for aqueous SCs and as an anode material for asymmetric supercapacitors.