A Review on Synthesis and Characterization of Activated Carbon from Natural Fibers for Supercapacitor Application

Supercapacitors have gained much attention in recent years due to their promising characteristics, such as high specific capacitance, high power density, long cycle life, and environment-friendly nature. Usage of natural sources for activated carbon synthesis is a major focus by many researchers worldwide for discovering a replacement of existing supercapacitors. This review summarizes the methods used to synthesize activated carbon (AC) from various natural fiber, their physical and electrochemical characteristics, and the improvement of supercapacitor electrode performance. Previous research studies indicate the practicability of activated carbon derived from various natural fibers with superior electrochemical properties. The effect of activating reagents and temperature on the electrochemical performance for supercapacitor applications are also highlighted in this paper. Since the nature of activated carbon from fibers and its synthesizing methods would result in different properties, the Cyclic Voltammetry (CV) study is also thoroughly discussed on the specific capacitance together with charge/discharge test to observe the capacitance retention after several cycles. Finally, a detailed approach of converting biowaste materials to activated carbon for energy storage applications with environmental concerns is explored.

Ultrathin Nanosheets-Assembled Nickel-Based Metal-Organic Framework Microflowers for Supercapacitor Application

Herein, we propose a solvent-assisted approach for preparing Ni-MOF microflowers with high specific capacitance and excellent rate capability as an electrode material for supercapacitors. Such high electrochemical performance is attributed...

Graphdiyne Oxide Composite Membranefor Active Electrolyte Enhanced Supercapacitor with super long self-discharge time

Activate electrolyte enhanced supercapacitors (AEESCs) are considered as promising tools for power capacity due to their high specific capacitance and simple creation form. However, there are many challenges, such as...

In-situ formation of MnO@N-doped carbon for asymmetric supercapacitor with enhanced cycling performance

Searching electrodes with high specific capacitance, rate capability, long cycling life and economic efficiency is central for next-generation supercapacitors. In this work, a hybrid electrode consisting of MnO and N-doped...

Highly ordered nanoscale phosphomolybdate-grafted polyaniline/metal hybrid layered structures prepared via secondary sputtering phenomenon as high-performance pseudocapacitor electrodes

The development of energy storage electrode materials is important for enhancing the electrochemical performance of supercapacitors. Despite extensive research on improving electrochemical performance with polymer-based materials, electrode materials with micro/nanostructures are needed for fast and efficient ion and electron transfer. In this work, highly ordered phosphomolybdate (PMoO)-grafted polyaniline (PMoO-PAI) deposited onto Au hole-cylinder nanopillar arrays is developed for high-performance pseudocapacitors. The three-dimensional nanostructured arrays are easily fabricated by secondary sputtering lithography, which has recently gained attention and features a high resolution of 10 nm, a high aspect ratio greater than 20, excellent uniformity/accuracy/precision, and compatibility with large area substrates. These 10nm scale Au nanostructures with a high aspect ratio of ~30 on Au substrates facilitate efficient ion and electron transfer. The resultant PMoO-PAI electrode exhibits outstanding electrochemical performance, including a high specific capacitance of 114 mF/cm2, a high-rate capability of 88%, and excellent long-term stability.

High Energy Storage Capabilities of CaCu3Ti4O12 for Paper-Based Zinc-Air Battery

A new perovskite material, CaCu3Ti4O12 (CCTO), is proposed as an efficacious electrocatalyst for oxygen evolution/reduction reactions for the development of zinc-air batteries (ZAB). Synthesis of this material adopted an effective oxalate route, which led to the purity in the electrocatalyst composition. The CCTO material is a proven potential candidate for energy applications because of its high dielectric permittivity (ε) and occupies an improved ORR activity with better onset potential, current density, and stability. The CCTO perovskite was also evaluated for the zinc-air battery as an air electrode, corresponding to the high specific capacitance of 1165 mAh g-1 with the greater cyclic efficiency and minimum variations in both charge/discharge processes. The highest power density (Pmax) measured was 32 mW cm-2. The OCV (Open Circuit Potential) obtained was 1.44 V for the as-developed battery. Also, the CCTO based paper battery shows an excellent performance achieving a specific capacity of 947.79 mAh g-1. The obtained results promise CCTO as a potential and cheap electrocatalyst for application in energy applications.

Review—Pseudocapacitive Energy Storage Materials from Hägg-Phase Compounds to High-Entropy Ceramics

Energy storage material that provide both high power and high energy density are needed to meet current needs. Pseudocapacitive materials have become a focus of research in the field of electrochemical energy storage because of their high specific capacitance and good rate performance. To increase the energy and power density, the key lies in selecting suitable electrode material types or optimizing the electrode layer structure to increase the potential window. This review, starting from the pseudocapacitive materials, introduces the energy storage mechanism of pseudocapacitance, describes the general development of pseudocapacitive materials including oxide materials and their derivative, development of Hägg-phase compounds extended by the MXenes in the past decade, and focuses on the development of several Hägg-phase compounds and the advantages of high-entropy ceramics as future pseudocapacitive materials. Due to the “high-entropy effect”, high-entropy ceramics have better physical and chemical properties to become the most candidate pseudocapacitive material. Focusing on the application potential of the high-entropy ceramics in pseudocapacitive research, they will provide a new pseudocapacitive material system.