Highly porous carbon with large electrochemical ion absorption capability for high-performance supercapacitors and ion capacitors

Recent Advances in Functionalized Biomass-Derived Porous Carbons and their Composites for Hybrid Ion Capacitors

Hybrid ion capacitors (HICs) have aroused extreme interest due to their combined characteristics of energy and power densities. The performance of HICs lies hidden in the electrode materials used for the construction of battery and supercapacitor components. The hunt is always on to locate the best material in terms of cost-effectiveness and overall optimized performance characteristics. Functionalized biomass-derived porous carbons (FBPCs) possess exquisite features including easy synthesis, wide availability, high surface area, large pore volume, tunable pore size, surface functional groups, a wide range of morphologies, and high thermal and chemical stability. FBPCs have found immense use as cathode, anode and dual electrode materials for HICs in the recent literature. The current review is designed around two main concepts which include the synthesis and properties of FBPCs followed by their utilization in various types of HICs. Among monovalent HICs, lithium, sodium, and potassium, are given comprehensive attention, whereas zinc is the only multivalent HIC that is focused upon due to corresponding literature availability. Special attention is also provided to the critical factors that govern the performance of HICs. The review concludes by providing feasible directions for future research in various aspects of FBPCs and their utilization in HICs.

Hierarchical porous carbon derived from petroleum coke via one-step chemical activation for the fabrication of a supercapacitor and real time clock application

The escalating demand for energy requires highly efficient energy storage devices and advanced materials. Low-cost carbon resources and their derivatives have always been a topical research area. Petroleum coke is an abundant and affordable resource that contributes to the scalability and cost effectiveness of carbon materials. Porous carbon derivatives have acquired great attention for energy storage and conversion owing to their large surface area, environmental friendliness, exceptional electrical conductivity, and economic viability. Thus, in this work, we directly synthesized hierarchical porous carbon materials from oil refinery petroleum coke (pet-coke) using a single-step KOH activation method to utilize them for the fabrication of a coin cell supercapacitor for electronic application. The synthesized pet-coke based porous carbon shows a high specific surface area (1108 m2 g-1) and excellent porosity. After conducting extensive electrochemical analysis, it shows promising specific capacitances of 170 and 70 F g-1 in aqueous and organic electrolytes, respectively. Further, a coin cell supercapacitor was fabricated using the pet-coke derived porous carbon in an organic electrolyte with a potential window of 2.7 V, demonstrating superior rate capability and durability. The calculated energy and power density of the fabricated coin cell indicate its favorable supercapacitor application to act as a backup power source for real time clock (RTC) application in electronics.

Electrochemical energy storage electrodes from fruit biochar

This review investigates the electrochemical energy storage electrode (EESE) as the most important part of the electrochemical energy storage devices (EES) prepared from fruit-derived carbon. The EES devices include batteries, supercapacitors, and hybrid devices that have various regular and advanced applications. The preparation of EESE from fruit wastes not only reduce the price of the electrode but also lead to enhance the electrochemical properties of the electrode. The astonishing results of fruits biochar at electrochemical analyses guarantee the performance of these electrodes as EESE. Also, using fruit waste as the precursor of the EESE due to protect the environment and reduce environmental pollutions.

Advanced Materials for Sodium-Ion Capacitors with Superior Energy-Power Properties: Progress and Perspectives

Developing electrochemical energy storage devices with high energy-power densities, long cycling life, as well as low cost is of great significance. Sodium-ion capacitors (NICs), with Na⁺ as carriers, are composed of a high capacity battery-type electrode and a high rate capacitive electrode. However, unlike their lithium-ion analogues, the research on NICs is still in its infancy. Rational material designs still need to be developed to meet the increasing requirements for NICs with superior energy-power performance and low cost. In the past few years, various materials have been explored to develop NICs with the merits of superior electrochemical performance, low cost, good stability, and environmental friendliness. Here, the material design strategies for sodium-ion capacitors are summarized, with focus on cathode materials, anode materials, and electrolytes. The challenges and opportunities ahead for the future research on materials for NICs are also proposed.

Synthesis of Diverse Green Carbon Nanomaterials through Fully Utilizing Biomass Carbon Source Assisted by KOH

With multiple properties, green carbon nanomaterials with high specific surface area have become extensively attractive as energy storage devices with environmental-friendly features. The primary synthesis attempts were based on alkalis activation, which, however, faced the dilemma of low utilization rate of carbon sources. Herein, the green carbon with ultrahigh surface area (up to 3560 m²/g) was prepared by the KOH-assisted biomass carbonization. Moreover, the redundant K₂O steam and C_xH_y flow were further utilized; as a result, the carbon materials with a wide range of morphological diversity were collected on the Cu foam. Accordingly, we carried out density functional theory simulations to reveal the mechanism of O-adatom-promoted CH₄ dissociation over the Cu surface for carbon formation. The electrodes of electrochemical capacitor fabricated by carbon synthesis possess a 170% higher specific capacitance compared with commercial carbon electrodes. As such, this strategy might be promising in developing hierarchical carbons along with sufficient carbon sources for broadening their potential applications.

Facile one-pot hydrothermal synthesis of particle-based nitrogen-doped carbon spheres and their supercapacitor performance

Particle-based nitrogen-doped carbon spheres (PNCSs) were prepared via a hydrothermal and carbonization route and PNCSs-1.2 demonstrated an enhanced supercapacitor performance.