Energy generation can be clean and sustainable if it is dependent on renewable resources and it can be prominently utilized if stored efficiently. Recently, biomass-derived carbon and polymers have been focused on developing less hazardous eco-friendly electrodes for energy storage devices. We have focused on boosting the supercapacitor’s energy storage ability by engineering efficient electrodes in this context. The well-known conductive polymer, polyaniline (PANI), deposited on nickel foam (NF) is used as a positive electrode, while the activated carbon derived from jute sticks (JAC) deposited on NF is used as a negative electrode. The asymmetric supercapacitor (ASC) is fabricated for the electrochemical studies and found that the device has exhibited an energy density of 24 µWh/cm2 at a power density of 3571 µW/cm2. Furthermore, the ASC PANI/NF//KOH//JAC/NF has exhibited good stability with ~86% capacitance retention even after 1000 cycles. Thus, the enhanced electrochemical performances of ASC are congregated by depositing PANI on NF that boosts the electrode’s conductivity. Such deposition patterns are assured by faster ions diffusion, higher surface area, and ample electroactive sites for better electrolyte interaction. Besides advancing technology, such work also encourages sustainability.

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Boosting the Electrochemical Performance of Polyaniline by One-Step Electrochemical Deposition on Nickel Foam for High-Performance Asymmetric Supercapacitor

Nowadays, the energy storage systems based on lithium-ion batteries, fuel cells (FCs) and super capacitors (SCs) are playing a key role in several applications such as power generation, electric vehicles, computers, house-hold, wireless charging and industrial drives systems. Moreover, lithium-ion batteries and FCs are superior in terms of high energy density (ED) as compared to the SCs. But, the down-side associated with them is the low power density (PD). On the other hand, this high PD feature is essential for the enhancement of dynamic performance of the system. Therefore, the SCs are well utilized due to their dominant features such as high specific power, rapid charging-discharging rate and superior cycling life. Hence, this paper mainly focuses on the advancements of various types of SCs along with their performance improvement methods. The important properties and selection of the electrode and electrolyte materials are described in detail. The commercially available SCs are enumerated with much more emphasis on their Figure of Merits (FOMs). Furthermore, the prominent role of SCs is highlighted with respect to the aforementioned applications. Finally, the future challenges associated with the SCs are presented. This review paper gives insightness for the design engineers and researchers in order to fill the research gaps associated with the SCs. 

Super capacitors for energy storage: Progress, applications and challenges

• The recent progress of transition metal oxides and chalcogenides for supercapacitors is provided. • The crystal structure and electrochemical performance of 2D layer and 3D spinel transition metal oxides and chalcogenides are discussed and the basic rules are summarized. • The strategies to improve the electrochemical performance of transition metal oxides and chalcogenides are detailed. • In / ex situ techniques and theoretical calculation are discussed to explorer the fundamental mechanism of transition metal oxides and chalcogenides. Supercapacitors (SCs) possesses high energy density, high power density and long cyclic performance. This review details the application of transition metal oxides and chalcogenides (TMOs and TMChs) in pseudo-capacitors and hybrid supercapacitors (PCs and HSCs). TMOs and TMChs with layer and spinel crystal structure are discussed. The layer materials exhibit excellent capacity and rate performance but inferior cycling performance; On the contrary, spinel materials have a more stable structure and perform better cyclic performance. TMOs suffer sluggish electrochemical kinetics and poor conductivity; TMChs can make up the defects of their TMOs counterparts. Next, strategies to improve the electrochemical performance of PCs and HSCs based on TMOs and TMChs are detailed, mainly from two aspects: designing the composition, optimizing the structures/morphologies of materials, and improving the conductivity of materials in materials’ aspects; increasing the mass-loading of electrodes, fabricating free-standing electrode and assembling flexible SCs in technical aspects. Furthermore, in/ex situ techniques and theoretical calculation are discussed to explorer the fundamental mechanism of TMOs and TMChs. Lastly, the future research orientations of SCs are also timely concluded. HSCs based on TMOs and TMChs are the hotpot in the future. . 

Recent advances of transition metal oxides and chalcogenides in pseudo-capacitors and hybrid capacitors: A review of structures, synthetic strategies, and mechanism studies

The demand for energy storage devices with high energy and power densities has increased tremendously in this rapidly growing world. Conventional capacitors, fuel cells, and lithium‐ion batteries have been used as energy storage devices for the long term. However, supercapacitors are one of the most promising energy storage devices because of their high specific capacitance, high power density, and longer cycle life. Recent research has focused on synthesizing transition‐metal oxides/hydroxides, carbon materials, and conducting polymers as supercapacitor electrode materials. The performance of supercapacitors can be improved by altering electrolytes, electrode materials, current collectors, experimental temperatures, and film thickness. Thousands of papers on supercapacitors have already been published, reflecting the significance and elucidating how much demanding such energy storage devices for this fast‐growing generation. This review aims to illustrate the electrode materials loaded on various conductive substrates by electrochemical deposition employed for supercapacitors to provide broad knowledge on synthetic pathways, which will pave the way for future research. We also discussed the basic parameters involved in supercapacitor studies and the advantages of the electrochemical deposition techniques through literature analysis. Finally, future trends and directions on exploring metals/metal composites toward designing and constructing viable, high‐class, and even newly featured flexible energy storage materials, electrodes, and systems are presented.

Recent Advancements in Electrochemical Deposition of Metal‐Based Electrode Materials for Electrochemical Supercapacitors

Metal‐Organic Frameworks (MOFs), a novel class of porous extended crystalline structures, are favored in different fields of heterogeneous catalysis, CO2 separation and conversion, and energy storage (supercapacitors) due to their convenience of synthesis, structural tailor‐ability, tunable pore size, high porosity, large specific surface area, devisable structures, and adjustable compositions. Nickel (Ni) is a ubiquitous element extensively applied in various fields of catalysis and energy storage due to its low cost, high abundance, thermal and chemical stability, and environmentally benign nature. Ni‐based MOFs and their derivatives provide us with the opportunity to modify different properties of the Ni center to improve their potential as heterogeneous catalysts or energy storage materials. The recent achievements of Ni−MOFs and their derivatives as catalysts, membrane materials for CO2 separation and conversion, electrode materials and their respective performance have been discussed in this review.

Potential Applications of Nickel‐Based Metal‐Organic Frameworks and their Derivatives

Supercapacitors (SCs) have received much interest due to their enhanced electrochemical performance, superior cycling life, excellent specific power, and fast charging–discharging rate. The energy density of SCs is comparable to batteries; however, their power density and cyclability are higher by several orders of magnitude relative to batteries, making them a flexible and compromising energy storage alternative, provided a proper design and efficient materials are used. This review emphasizes various types of SCs, such as electrochemical double-layer capacitors, hybrid supercapacitors, and pseudo-supercapacitors. Furthermore, various synthesis strategies, including sol-gel, electro-polymerization, hydrothermal, co-precipitation, chemical vapor deposition, direct coating, vacuum filtration, de-alloying, microwave auxiliary, in situ polymerization, electro-spinning, silar, carbonization, dipping, and drying methods, are discussed. Furthermore, various functionalizations of SC electrode materials are summarized. In addition to their potential applications, brief insights into the recent advances and associated problems are provided, along with conclusions. This review is a noteworthy addition because of its simplicity and conciseness with regard to SCs, which can be helpful for researchers who are not directly involved in electrochemical energy storage.

Shaista Bibi

Papers

A Review of Supercapacitors: Materials Design, Modification, and Applications