Electrochemical Energy Storage Applications Research Articles

WS2/Mesoporous Carbon Nanostructures as a Bifunctional Electrode for All Quasi‐Solid‐State Supercapacitor and Oxygen Evolution Reaction

Abstract2D transition‐metal sulfides have developed as favorable electroactive materials for electrochemical energy storage and conversion applications. In this work, WS2/mesoporous carbon (MC) is developed by a one‐step hydrothermal technique for supercapacitor and oxygen evaluation reaction (OER) application. However, the metal sulfides have poor rate and cyclic performance due to the aggregations between two layers of structures restricting their performance. The interaction between WS2 nanosheets and MC produces a synergistic effect, resulting in a decent electrochemical energy storage and conversion application. The synthesized materials used to prepare quasi‐solid‐state symmetric (QSSS) and asymmetric (QSSA) supercapacitor configuration enable the highest specific capacitance (CSP) of 305.45 F g−1 and 204.21 F g−1@ 10 mV s−1, respectively. Moreover, the specific energy and power density of QSSS and QSSA devices are 31.1 Wh kg−1 @824.95 W kg−1 and 24.74 Wh kg−1 @549.84 W kg−1, respectively. Additionally, the multifunctionality of the synthesized binary nanocomposite is also tested for OER. The composite shows a desirable over potential of 307 mV in 6 m KOH electrolyte, with a 69 mV dec−1 Tafel slope. The dual role of WS2/MC for energy storage and oxygen evaluation reaction conversion reveals the potential of metal sulfides.

Adapting Crystal Structure and Grain Boundaries through Sm3+ Doping in Na3Zr2Si2PO4 for Boosting Applicability in Sodium Solid-State Batteries.

Solid-state sodium batteries represent a highly promising option for future electrochemical energy storage applications. The ionic conductivity of solid-state electrolytes is one of the significant factors limiting the development of solid-state batteries. In this study, we establish that Sm3+ doping effectively boosts the ionic conductivity of Na3Zr2Si2PO12 (NZSP). The optimal composition, Na3.2Zr1.8Sm0.2Si2-PO12 (NZSP-S20), exhibits a total conductivity of 1.87 mS cm-1 at 23 °C. Structural and microscopic morphology analyses reveal that Sm3+ doping enhances the ionic conductivity of NZSP through structural modulation, phase fraction adjustment, and grain size reduction. High-frequency impedance spectroscopy (40 Hz to 110 MHz) demonstrates that bulk and grain boundaries contribute 49.4 and 50.6%, respectively, to the total conductivity. The structural and microscopic morphology analyses reveal that Sm3+ doping enhances the ionic conductivity of NZSP. Furthermore, the critical current density (CCD) attained in the symmetric cell, assembled by using NZSP-S20 as the solid-state electrolyte and NaSn alloy as the electrode, reaches 2.2 mA cm-1. These results furnish a theoretical foundation for comprehending the modification of solid-state electrolytes.

Enhancing electrical conductivity in zirconium-doped SiC ceramics through synergistic effects of crystal structure and free carbon control.

Polymer-derived ceramics (PDCs) have risen to prominence for applications in electrochemical energy storage, electromagnetic absorbing, and sensing materials, among others. However, a multitude of critical properties in PDCs are still limited by their intrinsic poor electrical conductivity. Herein, novel vinyl and zirconium-modified polycarbosilane precursors with improved electrical conductivity were synthesized through a Grignard coupling reaction of vinyl magnesium chloride and zirconocene dichloride, followed by the insertion polymerization with dichlorodimethylsilane and sodium. Our findings reveal a complex structural evolution from amorphous ZrO2 to distinct phases like m-ZrO2, t-ZrO2, and ZrC. This transformation significantly impacts the distribution and morphology of free carbon ribbons, influencing the material conductive network and resulting in an enhanced electrical conductivity of 0.28 S cm-1 and reduced bandgap. Through density functional theory analysis, a unique interaction between the energy bands of the carbon ribbons and the native cell is discovered, leading to a narrowed energy bandgap and conductive behavior. This advancement not only offers insight into the material structure-conductivity relationship but also opens new avenues for applications such as lithium battery anodes.

Two new 6-nitrobenzimidazole ligand-modified polymolybdate-based metal–organic complexes with excellent capacitive and electrocatalytic performances

6-Nitrobenzimidazole ligand was first introduced into polyoxometalate-based metal–organic architecture, and two unique butterfly-like complexes were obtained. Their applications in electrochemical energy storage and electrocatalysis were studied.

Arresting dissolution of two-dimensional metal-organic frameworks enables long life in electrochemical devices.

Two-dimensional conjugated metal-organic frameworks (2D cMOFs) are emerging as promising materials for electrochemical energy storage (EES). Despite considerable interest, an understanding of their electrochemical stability and the factors contributing to their degradation during cycling is largely lacking. Here we investigate three Cu-based MOFs and report that the dissolution of 2D cMOFs into electrolytes is a prevalent and significant degradation pathway. Several factors, such as the inherent solubility of ligands in electrolyte solvents and the duration of charge-discharge cycling exert a strong influence on the dissolution process. When these factors combine within a MOF, severely limited cycling stability is observed, with dissolution accounting for up to 80% of capacity degradation. Conversely, excellent cycling stability is observed when testing a Cu-MOF with a sparingly soluble ligand within an optimized potential window. Overall, these findings represent essential insights into the electrochemical stability of 2D cMOFs, offering crucial guidelines for their targeted development in EES applications.

Recent advances in hydrothermally and solvothermally grown Co3O4 nanostructures for electrochemical energy storage (EES) applications: a brief review

Hierarchical and porous structures, composed of diverse nanostructures are synthesized through hydrothermal and solvothermal growth processes of Co3O4 on various substrates, offer promising avenues for improving energy storage technologies.

Unravelling the role of pore structure of biomass-derived porous carbon in charge storage mechanisms for supercapacitors.

This study presents findings on the production and analysis of activated carbon (AC), which exhibits a significantly expansive surface area derived from readily available and inexpensive agroforestry waste, specifically coconut shells. The carbon materials displayed encouraging features for electrochemical energy storage applications with a high specific surface area (2920 m2 g-1), an ordered mesoporous structure (∼2.5 nm), and substantial electronic conductivity. By altering the surface properties of AC materials, they exhibited different energy storage responses while using an ionic liquid as an electrolyte. Electrodes composed of AC sourced from coconut shells demonstrated notably high specific capacitance (78 F g-1) and retained capacitance when assessed within symmetric electrical double-layer capacitors (EDLCs) employing organic electrolytes. Interestingly, the AC cell in an organic electrolyte delivered a specific energy (Es) of 67 W h kg-1 at a specific power (Ps) of 1237 W kg-1 at the current density of 1 A g-1 and still provided Es of 64, 60, 58, 57, and 52 W h kg-1 at Ps of 2477, 3724, 4971, 6218 and 12 480 W kg-1 at the current density of 2, 3, 4, 5 and 10 A g-1. This work demonstrates the effect of different pore volumes on the electrocatalytic activity of AC derived from natural product waste. Our results indicate the feasibility of employing these electrodes for lab-scale applications. Thus, the AC material emerges as a highly promising substance, poised to advance the creation of cost-efficient, environmentally sustainable, high-performance, high-power devices.

Prospects of polymer coatings for all solid-state and emerging Li-ion batteries

We summarize the influence of polymer coatings on cathode particles for electrochemical energy storage applications. We report on the effect of different polymer types, their properties, and their influence on thermo-electro-chemical behavior.

The synthesis and supercapacitor application of flexible free-standing Ti3C2Tx, Mo2TiC2Tx, and V4C3Tx MXene films.

MXenes represent a fascinating category of two-dimensional materials made up of transition metal carbides and nitrides, currently attracting significant research attention, especially in energy storage. However, the electrochemical properties of MXene materials with varying elemental compositions may exhibit significant differences. In order to optimally select types of MXenes that are more suitable for energy storage and explore their energy storage mechanisms, three kinds of different elemental compositions of delaminated MXenes (d-Ti3C2Tx, d-Mo2TiC2Tx, and d-V4C3Tx) were prepared by solid-phase synthesis, liquid-phase etching, and mechanical exfoliation method, successively. The obtained single-layer or few-layer MXene nanosheets were self-assembled into flexible free-standing film electrodes via vacuum-assisted filtration, and the detailed material preparation and characterization can guide the synthesis of more MXenes. Furthermore, we conducted a comprehensive study on the effects of various aqueous electrolytes (3 M H2SO4, 3 M KOH, and 3 M Na2SO4) and temperatures (0 °C, 20 °C, and 40 °C) on their electrochemical performance. This work optimized the MXene types that are more suitable for electrochemical energy storage application (d-Ti3C2Tx and d-V4C3Tx), and also found that the V4C3Tx MXene has excellent rate performance and long cycling performance, and has guiding significance for the development of MXene materials in energy storage. More significantly, the d-V4C3Tx MXene exhibits exceptional specific capacitance in both acidic and alkaline electrolytes, reaching 292.0 F g-1 in 3 M H2SO4, the highest among the three types of MXenes, and 184.3 F g-1 in 3 M KOH, far surpassing the performance of the d-Mo2TiC2Tx and d-Ti3C2Tx MXenes (less than 100 F g-1 at 2 mV s-1). Furthermore, this reveals that H+ intercalation/deintercalation, showing pseudocapacitance characteristics, along with the large interlayer spacing play a vital role in energy storage for MXenes, and an asymmetric configuration is an effective means to improve the energy density of aqueous supercapacitors. The comparative analysis aims to enhance the understanding of MXene materials' potential in advanced energy storage systems.

Innovative solvent-free compound-direct synthesis of defect-rich ultra-thin NiS nanosheets for high-performance supercapacitors.

Defect engineering in NiS nanosheets is an effective method to improve their surface properties and electronic structure for promoting electrochemical properties. However, a tunable, simple, and safe strategy for the introduction of abundant defect sites with a high activity into NiS with a special microstructure is worth developing. Herein, a novel hierarchical micro-flower-like NiS using graphene-like ultra-thin nanosheets with abundant defects as the building blocks was facilely synthesized by an innovative solvent-free compound-direct reaction strategy, which employed cost-efficient NaCl as the friction agent and dispersant to ensure adequate contact between sulfur ions and nickel ions and regulate the growth direction of NiS. Graphene-like ultra-thin NiS nanosheets effectively shorten the transport distance of ions and electrons. Defect engineering in NiS nanosheets provides more adsorption and storage sites for ions and high-activity sites for electrode materials, as well as adjusts the local electronic structure so as to effectively promote ion diffusion and charge transfer. The high performance of the as-obtained N-NiS electrode is illustrated by fabricating an asymmetric supercapacitor, which exhibits a specific capacitance of 351.5 F g-1 and energy density of 71.0 W h kg-1 at a power density of 229.3 W kg-1. The solvent-free compound-direct reaction strategy demonstrated in this study provides a new direction for the synthesis of high-performance nanomaterials for electrochemical energy storage applications.

Metal-free platforms for molecular thin films as high-performance supercapacitors.

Controlling chemical functionalization and achieving stable electrode-molecule interfaces for high-performance electrochemical energy storage applications remain challenging tasks. Herein, we present a simple, controllable, scalable, and versatile electrochemical modification approach of graphite rods (GRs) extracted from low-cost Eveready cells that were covalently modified with anthracene oligomers. The anthracene oligomers with a total layer thickness of ∼24 nm on the GR electrode yield a remarkable specific capacitance of ∼670 F g-1 with good galvanostatic charge-discharge cycling stability (10 000) recorded in 1 M H2SO4 electrolyte. Such a boost in capacitance is attributed mainly to two contributions: (i) an electrical double-layer at the anthracene oligomer/GR/electrolyte interfaces, and (ii) the proton-coupled electron transfer (PCET) reaction, which ensures a substantial faradaic contribution to the total capacitance. Due to the higher conductivity of the anthracene films, it possesses more azo groups (-N[double bond, length as m-dash]N-) during the electrochemical growth of the oligomer films compared to pyrene and naphthalene oligomers, which is key to PCET reactions. AC-based electrical studies unravel the in-depth charge interfacial electrical behavior of anthracene-grafted electrodes. Asymmetrical solid-state supercapacitor devices were made using anthracene-modified biomass-derived porous carbon, which showed improved performance with a specific capacitance of ∼155 F g-1 at 2 A g-1 with an energy density of 5.8 W h kg-1 at a high-power density of 2010 W kg-1 and powered LED lighting for a longer period. The present work provides a promising metal-free approach in developing organic thin-film hybrid capacitors.

In situ growth of binder-free CoNi0.5-MOF/CC electrode for high-performance flexible solid-state supercapacitor application.

Metal organic frameworks (MOFs) with binder-free electrodes have shown promise for portable electrochemical energy storage applications. However, their low specific capacitance and challenges associated with the attachment of active materials to the substrate constrain their practical utility. In this research, we prepared a CoNi0.5-MOF/CC electrode by in situ growth of CoNi0.5-MOF on an H2O2-pretreated carbon cloth (CC) without using any binder. It exhibits a higher specific capacitance of 1337.5 F g-1 than that of CoNi0.5-MOF (∼578 F g-1) at a current density of 1 A g-1 and an excellent rate ability of 88% specific capacitance retention at a current density of 10 A g-1 after 6000 cycles. The as-assembled flexible asymmetric solid-state supercapacitor based on the CoNi0.5-MOF/CC positive electrode and a nitrogen-doped graphene (N-Gr) negative electrode exhibits an energy density of 61.46 W h kg-1 at a power density of 1244.56 W kg-1 and holds a stable capacitance of ∼125 F g-1 at 1 A g-1 when the flexible supercapacitor is bent, showing great potential for flexible electronics application. The H2O2 is indicated to play an important role, enhancing the adhesion of CoNi0.5-MOF on CC and reducing its charge transfer resistance by functionalizing the carbon fiber during the pretreatment of the CC matrix. The results provide a great way to prepare a flexible asymmetric solid-state supercapacitor with both high power density and high energy density for practical application.

Studying Possibilities of Poly(benzoquinone-hydrazine) for Electrochemical Energy Storage Application

Studying Possibilities of Poly(benzoquinone-hydrazine) for Electrochemical Energy Storage Application

Multi‐scale structure engineering of covalent organic framework for electrochemical charge storage

AbstractCovalent organic frameworks (COFs), which are constructed by linking organic building blocks via dynamic covalent bonds, are newly emerged and burgeoning crystalline porous copolymers with features including programmable topological architecture, pre‐designable periodic skeleton, well‐defined micro‐/meso‐pore, large specific surface area, and customizable electroactive functionality. Those benefits make COFs as promising candidates for advanced electrochemical energy storage. Especially, for now, structure engineering of COFs from multi‐scale aspects has been conducted to enable optimal overall electrochemical performance in terms of structure durability, electrical conductivity, redox activity, and charge storage. In this review, we give a fundamental and insightful study on the correlations between multi‐scale structure engineering and eventual electrochemical properties of COFs, started with introducing their basic chemistries and charge storage principles. The careful discussion on the significant achievements in structure engineering of COFs from linkages, redox sites, polygon skeleton, crystal nanostructures, and composite microstructures, and further their effects on the electrochemical behavior of COFs are presented. Finally, the timely cutting‐edge perspectives and in‐depth insights into COF‐based electrode materials to rationally screen their electrochemical behaviors for addressing future challenges and implementing electrochemical energy storage applications are proposed.

Enhancing the electrochemical and photoelectrochemical effects in CNTs@CoMgS@AC nanocomposite based electrode materials for advanced hybrid supercapacitors

Hybrid supercapacitors (HSCs) have received a lot of interest because of their excellent stability and energy storage capacity. To design a HSC device, we synthesized cobalt magnesium sulfide (CoMgS) using an easy hydrothermal technique. Thesurface properties, crystallinity, elemental analysis, and homogeneity are analysed. The CNT@CoMgS nanocomposite is demonstrated a considerably improved specific capacity (Qs) of 698.88C/g or 1164.8F/g compared to the other samples. The CNT@CoMgS//AC-based HSC revealed a high Qs value of 249.88C/g and an energy density of 70 Wh/kg with an astonishing power density of 880 W/kg. In photoelectrochemical activity, the CNT@CoMgS electrode exhibited a fast response and recovery time with good photoactivity, which is used to perform excellent photo switching. Hence, the CNT@CoMgS@AC electrode demonstrated extraordinary performance because of its largesurface area, quick transport of charge carriers, and extraordinary rate capability, which emphasizes its promise for electrochemical energy storage applications.

Metal(Pt, Pd)-Perovskite Oxide(Ba0.5Sr0.5Co0.8Fe0.2O3-δ) Hybrid Material As a Bifunctional Electrocatalyst for Lithium-Air Battery

The rapid depletion of fossil fuel resources and growing concerns over climate change have made the development of next-generation batteries a top priority. Among these, Li-O2 batteries have attracted significant interest due to their potential for much higher gravimetric energy storage density compared to other chemical batteries. However, efficient and cost-effective catalysts for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are critical for the efficient functioning of these batteries.In recent years, complex perovskite oxides, such as Ba0.5Sr0.5Co0.8Fe0.2O3-δ (BSCF), have been identified as promising candidates for bifunctional catalysts due to their defective structures and excellent oxygen mobility. However, while BSCF exhibits high OER activity, its ORR performance is poor. To address this issue, researchers have turned to metal-oxide composite catalysts, where nanosized metals are deposited on the surface of perovskite oxides, to increase activity and stability towards ORR due to the synergistic effect between metal and oxide support.In this study, we report the development of bifunctional electrocatalysts with highly electrocatalytic activity for ORR and OER. We used a simple wet-chemical processing technique to deposit metal catalysts with superior ORR activity on perovskite oxide-based catalysts with high OER activity. The direct deposition method is an effective way to create a good distribution of metal catalysts, intimate contact between metal catalysts and BSCF perovskite oxide, which may contribute to the creation of a synergistic effect between them. Our results showed that the metal catalysts deposited on perovskite oxides of Pd@BSCF and Pt@BSCF exhibited better ORR activity than others and higher OER activity than the perovskite oxides alone, resulting in much-enhanced bifunctionality through a synergistic effect between the metal catalysts and perovskite oxides.We further investigated the enhanced bifunctional electrocatalytic activity of the metal catalysts deposited perovskite oxides for Li-O2 batteries. The assembled Li-O2 batteries with Pd@BSCF cathode demonstrated lower discharge/charge overpotential (0.8 V at the cutoff capacity of 500 mAh gcat -1) and improved cycling stability (over 70 cycles), indicating the effectiveness of our approach in enhancing the bifunctional activities of ORR and OER for application in electrochemical energy storage and conversion systems. The encouraging results obtained from this study might have been attributed to two mechanisms, namely, the synergistic effect of electronic transfer and RDS/spillover. Our study suggests that the deposition of metal catalysts on the surface of perovskite oxides (Pd@BSCF and Pt@BSCF) is an effective approach to enhance bifunctional activities of ORR and OER, making it a promising strategy for the development of next-generation batteries. Figure 1

High-Rate Electrochemical Energy Storage of MXene in Neutral Aqueous Electrolytes

Increasing demand for electrochemical energy storage devices with high energy density, high power density, and long lifespan has posed significant challenges for developing suitable electrodes and electrolyte systems with fast charge transport kinetics and superior cycling stability.1 As one of the promising electrode materials explored recently, MXenes (Mn+1XnT x ) are a group of two-dimensional transition metal carbides and/or nitrides, in which M is early transition metal, X presents C and/or N, T x stands for the surface groups such as =O, -OH, -Cl or -F. They exhibit excellent high-rate performance in electrochemical energy storage applications due to their unique properties: superior electronic conductivity (~15 000 S cm-1) and large interlayer spacing (~1 nm).2 The charge storage mechanism and performance of the MXenes electrode is highly dependent on the electrode and electrolyte composition. For example, Ti3C2T x has shown rapid pseudocapacitive (de)intercalation of protons and transformation between the oxygen surface groups (=O) and hydroxyl (-OH) groups in acidic aqueous electrolytes.3,4 As a result, Ti3C2T x exhibits an ultrahigh volumetric capacitance of 1500 F cm-3 in H2SO4 electrolyte.5 In less corrosive neutral aqueous electrolytes, the cation intercalation is accompanied by negligible charge transfer, leading to ultrafast charge storage.6 Consequently, a moderate capacitance with superior cycling stability is reported in neutral electrolytes compared to acidic electrolytes. In contrast to dilute aqueous electrolyte, which has a limited electrochemical stability window (ESW), the highly concentrated water-in-salt (WIS) electrolyte possesses a large ESW (∼3.0 V) owing to the depressed activity of free water. Besides, the unique solvation structure of WIS electrolyte induces a novel intercalation of fully-solvated Li+ at positive potential and increases the capacitance of MXene.7 As a result, WIS electrolyte helps overcome the drawback of the low energy density of MXene in neutral aqueous electrolytes.In our research, we explored the impact of MXene structure and a novel electrolyte system on the pseudocapacitive performance of MXene. The charge storage behavior of Ti3C2T x in a molecular crowding electrolyte was explored. Interestingly, Ti3C2T x displayed one pair of redox peaks with low polarization, differing from both dilute neutral aqueous electrolyte and WIS electrolyte, which may be attributed to the intercalation of Polyethylene glycol (PEG)-solvated Li+ cluster. The in situ X-ray diffraction are employed to better understand the charge storage process. We also constructed a MXene/polymer heterostructure with enlarged interlayer spacing. The unique heterostructure delivered a significantly enhanced rate performance in neutral aqueous electrolyte. (a high capacitance retention of 81% at 10 A g-1)Reference: Simon, P. & Gogotsi, Y. Nature Materials 7, 845–854 (2008).Anasori, B. et al. Nature Reviews Materials 2, 16098 (2017).Mu, X. et al. Advanced Functional Materials 29, 1902953 (2019).Zhan, C. et al. J. Phys. Chem. Lett. 9, 1223–1228 (2018).Lukatskaya, M. R. et al. Nat Energy 2, 1–6 (2017).Ando, Y. et al. Advanced Functional Materials 30, 2000820 (2020).Wang, X. et al. ACS Nano 15, 15274–15284 (2021).

Synchrotron Capabilities in a Laboratory Setting: In Situ X-Ray Absorption Spectroscopy of Disordered Vanadium Ferrite Electrodes for Lithium-Ion Batteries

X-ray absorption spectroscopy (XAS) provides important information on metal oxidation state andelement-specific coordination, but data collection has historically required the energy specificityand brilliance of a synchrotron facility. Recent developments in detectors and optics are nowbringing XAS capabilities to the laboratory setting through multiple commercially availableinstruments. At the U.S. Naval Research Laboratory, we use laboratory-based XAS to explore thelocal electronic and atomic structure of a class of disordered vanadium ferrite (VFe2Ox) aerogelsthat exhibit promising performance for electrochemical energy-storage applications such asrechargeable lithium-ion batteries.1,2 These materials are synthesized by an epoxide-promoted sol–gel reaction of iron chloride and vanadium isopropoxide, with the resulting fluid-filled gelsrendered as high surface area aerogels via supercritical-CO2 drying. During the initial sol–gelsynthesis, electroinactive metals such as aluminum, zinc, and zirconium may also be substitutedfor vanadium and iron to alter the local electronic environment and corresponding electrochemicalperformance of VFe2Ox. Heat treatment of as-dried VFe2Ox aerogels under either O2-containingor inert atmosphere yields disordered or nanocrystalline variants, respectively. The resulting seriesof native and substituted VFe2Ox materials are evaluated as powder-composite cathodes versuslithium metal in coin cells with conventional nonaqueous lithium-ion electrolyte. We correlatesuch critical battery-performance parameters as total specific capacity, high-rate capability, andcycle life as a function of VFe2Ox composition and its degree of structural order/disorder, asmeasured with in-situ XANES and EXAFS. In parallel with experimental observations,calculations on VFe2Ox reveal that V incorporates into the defective spinel structure at tetrahedralsites and that both disorder induced by vacancies and Fe/V tetrahedral occupation lowers theoverall energy and opens an electronic energy gap that establishes the redox sequence duringlithiation.1. C. N. Chervin, J. S. Ko, B. W. Miller, L. Dudek, A. N. Mansour, M. D. Donakowski, T.Brintlinger, P. Gogotsi, S. Chattopadhyay, T. Shibata, J. F. Parker, B. P. Hahn, D. R. Rolison,and J. W. Long, J. Mater. Chem. A 3, 12059 (2015).2. C. N. Chervin, R. H. DeBlock, J. F. Parker, B. M. Hudak, N. L. Skeele, J. S. Ko, D. R. Rolison,and J. W. Long, RSC Adv. 11, 14495 (2021).

Enhanced electrochemical and thermal stability of CdS:Pb2+, Cu2+ co-doped nanoparticles on energy storage applications

For the first time, we prepared the Pb2+, Cu2+ co-doped CdS nanoparticles that were prepared by a simple chemical precipitated method. Structural and lattice parameters were determined by XRD. It was found that mixed cubic-hexagonal crystal structure for the co-doped nanoparticles. Polyvinylpyrrolidone (PVP) was used as a surfactant to control particle size. The organic functional group's presence in the surfactant was identified by FT-IR. Two distinct morphologies were found for the co-doped sample that was studied by TEM. TG–DTA was used to study thermal stability and phase transition of the sample. CV analysis was used to determine the potential window of oxidation and reduction of the sample. In addition, VSM exhibits diamagnetic behavior for CdS:Pb:Cu nanoparticles. We found that the excellent electrochemical, thermal and magnetic properties of the co-doped CdS nanoparticles can be used for electrochemical energy storage applications.

Advances in Mn‐Based MOFs and Their Derivatives for High‐Performance Supercapacitor

AbstractAs the most widely used metal material in supercapacitors, manganese (Mn)‐based materials possess the merits of high theoretical capacitance, stable structure as well as environmental friendliness. However, due to poor conductivity and easy accumulation, the practical capacitance of Mn‐based materials is far lower than that of theoretical value. Therefore, accurate structural adjustment and controllable strategies are urgently needed to optimize the electrochemical properties of Mn‐based materials. Metal‐organic frameworks (MOFs) are porous materials with high specific surface area (SSA), tunable pore size, and controllable structure. These features make them attractive as precursors or scaffold for the synthesis of metal‐based materials and composites, which are important for electrochemical energy storage applications. Therefore, a timely and comprehensive review on the classification, design, preparation and application of Mn‐based MOFs and their derivatives for supercapacitors has been given in this paper. The recent advancement of Mn‐based MOFs and their derivatives applied in supercapacitor electrodes are particularly highlighted. Finally, the challenges faced by Mn‐MOFs and their derivatives for supercapacitors are summarized, and strategies to further improve their performance are proposed. The aspiration is that this review will serve as a beneficial compass, guiding the logical creation of Mn‐based MOFs and their derivatives in the future.