Electrodes For Energy Storage Systems Research Articles

High-performance cellulose-based nanostructured carbons for rechargeable batteries

Binder-free, highly porous carbon nanofibers (CNFs) with novel sponge-like pore structures were synthesized for the first time via centrifugal spinning of cellulose-based polymers, and SnO2 was introduced to improve the electrochemical performance. Cellulose-based binder-free centrifugally spun carbon-coated SnO2/carbon nanofibers (C@SnO2/CNFs) were employed as anodes in Na-ion batteries. Owing to their highly porous morphology with novel sponge-like pore structures and SnO2 nanoparticles providing rapid Na-ion transport, better electrolyte accessibility, and good mechanical strength, the C@SnO2/CNFs showed outstanding electrochemical performance, with a high reversible capacity of 660 mAh/g at 50 mA/g, high rate capability, and excellent cycling performance. The specific capacity of C@SnO2/CNFs was approximately 390 mAh/g after 2000 cycles at 0.2 A/g. These results prove that the combination of centrifugal spinning, carbon coating, and heat treatment is a promising and sustainable approach for creating cellulose-based carbon nanostructures with highly porous structures that can be used to synthesize high-performance electrodes for energy storage systems.

Facile synthesis of cryogenically controlled cobalt-nickel-based Prussian blue analogues for high-performance symmetric supercapacitors

Cobalt hexacyanoferrate (CoHCF) with high energy density as a potentially useful electrode for energy storage systems still suffers from inferior rate capability and low cycling performance due to high-spin nitrogen-coordinated Co ions. While nickel hexacyanoferrate (NiHCF) with low energy density can exhibit great cycling stability due to the electrochemical inertness of Ni. Herein, we have developed a series of cobalt nickel hexacyanoferrate (CoNiHCF) via a facile cryogenically controlled co-precipitation method. We explored the Co/Ni molar ratio and synthesis temperature on the effects of the specific capacitance in detail. As supercapacitor cathode, the Co0.7Ni0.3HCF with the Co/Ni molar ratio of 0.7:0.3 synthesized at 0 °C can exhibit a high specific capacitance of 406 F g−1 at 1 A·g−1 with capacitance retention of 81.89 % after 5000 cycles. The exceptional electrochemical performance is ascribed to the upgraded conductivity resulting from the coexistence of bimetallic components, the low particle size caused by the moderate introduction of Ni, the low interstitial water content, and the synergistic effect between Co and Ni. Moreover, the symmetric supercapacitor (SSC) of Co0.7Ni0.3HCF//Co0.7Ni0.3HCF can provide a high energy density of 72.96 W h kg−1 and 40.96 W h kg−1 at specific powers of 2876 W kg−1 and 28,577 W kg−1, respectively with a capacitance retention of 74.83 % after 4000 cycles.

Three-Dimensional Self-Supported Ge Anode for Advanced Lithium-Ion Batteries.

Three-dimensional (3D) self-supported Ge anode is one of the promising candidates to replace the traditional graphite anode material for high-performance binder-free lithium-ion batteries (LIBs). The enlarged surface area and the shortened ions/electrons transporting distance of the 3D electrode would greatly facilitate the rapid transfer of abundant lithium ions during cycling, thus achieve enhanced energy and power density during cycling. Cycle stability of the 3D self-supported Ge electrode would be improved due to the obtained enough space could effectively accommodate the large volume expansion of the Ge anode. In this review, we first describe the electrochemical properties and Li ions storage mechanism of Ge anode. Moreover, the recent advances in the 3D self-supported Ge anode architectures design are majorly illustrated and discussed. Challenges and prospects of the 3D self-supported Ge electrode are finally provided, which shed light on ways to design more reliable 3D Ge-based electrodes in energy storage systems.

Rational design of hierarchical nanoporous yolk-shell Co9S8@ZnGa2S4 heterostructured cages as novel electrode for energy storage systems

State-of-the-art nanomaterials with multi-components and complex topologies demonstrate tremendous potential in fabricating electrode materials with high performance which are used in green energy storage systems. Thereby, we report for the first time on the synthesis of hierarchical yolk-shell Co9S8@ZnGa2S4 heterostructured cages (HYC-CS@ZGS) by a facile metal−organic framework (MOF)-assisted approach as a new electrode material for enhanced hybrid supercapacitors (HSCs). Starting with a solid zeolitic imidazolate framework (ZIFs; termed ZIF-67) as the template, ZIF-67@ZIF-8 core-shell polyhedrons (CSPs) are obtained through an epitaxial growth process. Afterward, ZIF-67@ZIF-8 CSPs are controllably transformed into HYC-CS@ZGS via a reflux procedure. Taking advantage of the synergistic effects between the constituent metals and the hierarchical hollow geometry, the organized HYC-CS@ZGS cages exhibit superb electrochemical performance for supercapacitors (SCs). As a result, the electrode demonstrates an ultrahigh specific capacity of 1018C g−1 at 5 mA cm−2 with a 61 % capacity retention at an ultrahigh current density of 187.5 mA cm−2. Consequently, the assembled HYC-CS@ZGS//AC device renders the highest specific energy of 61.9 W h kg−1 at a specific power density of 64 kW kg−1 with excellent cycle life (just 8.7 % loss after 10,000 cycles).

Cobalt disulfide/polypyrrole cauliflower-like nanocomposite: Single-pot hydrothermal synthesis, characterization, and their enhanced storage energy in supercapacitors

This study investigates the effectiveness of CoS2/PPy nanocomposites as electrode materials for supercapacitors. We performed a simple and effective one-step hydrothermal fabrication of these nanostructures on nickel foam as substrate. After accurate characterization, electrochemical studies were performed using various techniques, such as cyclic voltammetry (CV), galvanostatic discharge (GCD), and electrochemical impedance spectroscopy (EIS). The result shows excellent electrochemical behaviour of the synthesized electrode with a specific capacitance of 605.2 C g−1 at a current density of 1 A g−1. Moreover, considerable capacitance retention (∼90.9% after 5000 cycles) was obtained. Next, an asymmetric supercapacitor was developed using a prepared electrode and activated carbon (AC /Ni foam) as cathode and anode, respectively. The device showed a high specific energy of 88.07 Wh kg−1 with a significant power of 4.95 kW kg−1 at an operating voltage of These unexpected results indicate that the CoS2/PPy nanostructure has the potential to become a promising electrode for energy storage systems.

Ion-Conducting Robust Cross-Linked Organic/Inorganic Polymer Composite as Effective Binder for Electrode of Electrochemical Capacitor

Poly(ionic liquid)s (PILs) are used in many electrochemical energy storage/conversion devices owing to their favorable physical properties. Therefore, PIL binders have been examined as polymeric binders for electrodes in energy storage systems (ESSs) and have shown superior performance. Several innovative technologies have been developed to improve the properties of polymers, with cross-linking being the most effective and easy strategy to achieve this. In this study, we designed a breakthrough complex cross-linking and composite technique that could successfully develop the physical properties of a polymer in a simple one-step process. Additionally, the technique could improve the thermal stability and mechanical properties of the polymer. The proposed polymeric binder showed better adhesion, higher capacitance, and good energy density with improved cyclic stability compared to that shown by conventional polyvinylidene fluoride (PVDF). This study revealed that cross-linked networks in polymeric binders are long-cycle-life features for electrochemical redox capacitors.

Fabrication of 3D microporous Ni foam for growing CoMoO4 nanosheet arrays as high-performance pseudocapacitive electrode

A 3D porous Ni foam with pore size in the range of several micrometers can accommodate more CoMoO 4 nanosheet arrays in a limited area with merit of high-efficient electron/ion transportation, thus leading to a high areal performance as pseudocapacitive electrode. • A novel 3D porous Ni foam current collector is fabricated by a scale-up method. • The interconnected pores can be controlled to accommodate electroactive materials with different mass loading values. • The 3DNF@CMO enables a shortened and homogeneous electron/ion transfer pathway. A 3D porous Ni foam (3DNF) with pore and ligament size in the ranging of several micrometers is fabricated via a method of combining nonsolvent induced phase separation (NIPs) and solid-state sintering. Benefiting from the interconnected pores, the pseudocapacitive CoMoO 4 nanosheet arrays can grow on the unique 3DNF (3DNF@CMO) with loading mass of 3.2 mg cm −2 . The 3DNF can act as a connection between internal and external circuit, ensuring rapid and stable electron/ion transfer. Because of these merits, the 3DNF@CMO-8 electrode shows a high area capacitance of 1.53F cm −2 at 3 mA cm −2 and long lifespans surpassing 8000 cycles. These results highlight the importance of rational design of 3D current collectors and reveal a promise for developing idea electrodes for energy storage systems.

Tunable Fabrication of Hollow Nano Sword-Like CuCo2O4 Derived from Bimetal–Organic Frameworks as Binder-Free Electrodes

This study successfully synthesized highly porous hollow nano sword-like CuCo2O4 with a large specific surface area (80.2 m2 g–1) on a nickel foam substrate through a simple solution-based method followed by a calcination process. Benefiting from their geometrical merits, including excellent structural robustness, large electroactive surface areas, and 3D open structures, the hollow nano sword arrays of CuCo2O4 deliver remarkable electrochemical performances for SCs. Using this binder-free strategy, the synthesized copper cobalt oxide electrode delivers a great specific capacity of 717 C g–1 at 1 A g–1 with an excellent rate capability and cycling stability in a three-electrode cell configuration. Consequently, the fabricated CCO-HS//AC device exhibits the highest specific energy of 54 Wh kg–1 at a specific power of 3137 W kg–1 with a remarkable cycle stability of 91.1% capacity retention after 8000 cycles, indicating its potential as a novel electrode for energy storage systems.

Data-driven machine learning approach for predicting the capacitance of graphene-based supercapacitor electrodes

Graphene-based nanocomposites have shown strong potential as active components of high-capacity supercapacitors electrodes in energy storage systems. Developing an accurate and effective prediction technique for electrochemical performance is essential to decrease the time required for designing and testing electrode materials. In the present study, experimental data from more than two hundred published research papers have been extracted and examined through several machine learning (ML) models to predict the specific capacitance (F/g) of graphene-based electrode structures using various physicochemical features and diverse electrochemical measurements. The physicochemical features used in this work to predict the specific capacitance of the SCs electrode material include: carbon, nitrogen, and oxygen atomic percentages as well as electrode configuration, pore size, pore-volume, specific surface area (SSA), and ID/IG ratio. Electrochemical test features obtained from galvanostatic charge-discharge (GCD) tests and electrochemical impedance spectroscopy (EIS) analyses for the same purpose include: cell configuration, electrolyte ionic conductivity, electrolyte concentration, applied potential window, current density, charge-transfer resistance (RCT), and equivalent series resistance (RS). Four different ML models were developed: k-nearest neighbors' regression (KNN), decision tree regression (DTR), Bayesian ridge regression (BRR), and artificial neural network (ANN). The developed ANN model, with root mean square error (RMSE) and coefficient of determination (R2) values of 60.42 and 0.88, respectively, delivers extremely accurate prediction results compared to the other models developed for this purpose. The SHAP (SHapley Additive exPlanations) framework analysis of the input characteristics revealed that atomic percentages of nitrogen and oxygen doped graphene had the greatest effect on the ANN model.

Coal-Based Electrodes for Energy Storage Systems: Development, Challenges, and Prospects

Coal-Based Electrodes for Energy Storage Systems: Development, Challenges, and Prospects

Synergic effect of physically-mixed metal organic framework based electrodes as a high efficient material for supercapacitors

Porous materials have been recently used for the development of hybrid supercapacitors (HSCs) because they can facilitate rapid electron and mass transportation for energy storage purposes. Among porous materials, metal-organic frameworks (MOFs) have attracted attention as working electrodes for HSCs owing to their controllable morphology and topology, large pore and porosity size, high specific surface area, and fascinating physicochemical properties. In this study, by using an easy and cost-effective method, a copper-based MOF (Cu-MOF), a nickel-based MOF (Ni-MOF), and a cobalt-based MOF (Co-MOF) were physically combined and employed as a working electrode for supercapacitors. They were analyzed in a three-electrode system. The cyclic voltammetry (CV) measurement at the scan rate of 10 mV s−1 in 6 M KOH aqueous electrolyte showed the specific capacitances (Cs) of 316, 898, and 1823 F g−1 for Co-MOF&Cu-MOF, Ni-MOF&Co-MOF and Ni-MOF&Cu-MOF electrode, respectively. The Ni-MOF&Cu-MOF showed the highest Cs arising from the synergic effects between MOFs and the presence of multiple valence states that increases the contact area for electrolytes in the nanocomposites. This strategy can open a new window to the high performance material and facile fabrication of binary MOFs electrodes for energy storage systems.

Sustainable-inspired design of efficient organic electrodes for rechargeable sodium-ion batteries: Conversion of P-waste into E-wealth device

Functionalized organic electrodes are most suitable for anodic part in sodium-ion (Na-ion) batteries due to eco-friendly nature, low cost, and to modify the structure. A very basic organic acid molecule, which is terephthalic acid (TPA) is synthesized from the environmental contaminant waste resource, polyethylene terephthalate (PET) water bottle via solvothermal method. The thermal instability and electrochemical performance of TPA have been improved through the formation of disodium terephthalate (Na2TP) by an acid-base reaction through the replacement of H+ ion from the acid molecule by Na+ ion. The electrochemically active Na2TP obtained from the waste PET bottles promises its usage as anodes for rechargeable Na-ion batteries. The average specific discharge capacity of Na2TP-55% exhibits 190 mAh g−1 with 97% coulombic efficiency (CE) and Na2TP/SWCNTs composite show an impressive average specific discharge capacity 241 mAh g−1 at C/10 rate with 98.5% CE along with stable cycling up to 50 cycles. The present approach to sustainably use discarded PET waste not only curbs polluting the environment but also foresees the future with a plastic-free environment by the sustainable conversion of solid PET bottle wastes into usable electrodes for energy storage systems with benefits such as low manufacturing cost and effective solid waste removal.

Facile synthesis of Zn3V2O8 nanostructured material and its enhanced supercapacitive performance

With a view to fabricate smart technology devices with portable features and with global energy security, researchers aimed to design high-performance electrode material to respond to the increasing demand for renewable energy storage systems. Nano Zn3V2O8 material was successfully synthesized via simple and low-cost chemical method. The structure and chemical conformation of the as-synthesized Zn3V2O8 were ascertained by physico-chemical techniques, respectively. BET results showed the mesoporous structure with specific surface area of 16 m2 g−1. Furthermore, its electrochemical performance was investigated in a three-electrode system. The as-synthesized Zn3V2O8 nanostructure exhibited high specific capacitance (Csp) of 471 F g-1 at 1 Acm−2 and cycling stability with 97% capacitance retention after 3000 cycles. The excellent performance of Zn3V2O8 nanostructure was related to its high conductivity and the fast electron/ions transportation. The unique features of Zn3V2O8 rendered it as superior electrode for energy storage systems.

High-Energy-Density Asymmetric Supercapacitor Based on a Durable and Stable Manganese Molybdate Nanostructure Electrode for Energy Storage Systems

The 3D interconnected MnMoO4 nanosheet arrays with abundant open spaces and ordered arrangements deposited on nickel foam (NF@MnMoO4) are fabricated by a mild one-step hydrothermal method. As integ...

PEDOT-modified laser-scribed graphene films as bginder– and metallic current collector–free electrodes for large-sized supercapacitors

The rapid development of wearable electronic devices and energy storage devices has increased the demand for flexible, lightweight, and durable supercapacitors. Nevertheless, the cost-effective synthesis of suitable active materials and the facile fabrication of electrodes for energy storage systems remain a challenge for practical applications. In this study, we developed a scalable method for the fabrication of graphene-based supercapacitors, by using a CO2 infrared laser to transform polyimide (PI) films into porous graphene. Furthermore, when modified with oxidatively polymerized poly (3,4-ethylenedioxythiophene) (PEDOT), the conductivity of the graphene films was enhanced significantly. The resultant films could be fabricated directly for use in supercapacitors without employing metallic current collectors. The current collector–free supercapacitors exhibited excellent electrochemical properties, rivaling those obtained from corresponding devices featuring metallic current electrodes. An assembled device having a large working area (4 × 4 cm2) displayed reversible capacities of 115.2, 97.0, and 78.4 F/g at rates of 0.5, 2, and 6 A/g, respectively. Moreover, only slight losses in capacitance occurred after 4000 charge/discharge cycles and 2000 bending cycles, indicative of remarkable cycling life and mechanical stability.

Advantageous Functional Integration of Adsorption‐Intercalation‐Conversion Hybrid Mechanisms in 3D Flexible Nb2O5@Hard Carbon@MoS2@Soft Carbon Fiber Paper Anodes for Ultrafast and Super‐Stable Sodium Storage

AbstractUsing synergetic effects of various sodium storage modes and materials to construct high power, high energy, and long cycling flexible sodium anode materials is significant and still challenging. Here, by advantageous functional integration of adsorption‐intercalation‐conversion sodium storage mechanisms, a 3D flexible fiber paper anode with the composition of Nb2O5@hard carbon@MoS2@soft carbon is designed and prepared. Based on the synergetic effects, it exhibits higher specific capacity than pure Nb2O5, with more excellent rate performance (245, 201, 155, 133, and 97 mAh g−1 at the current density of 0.2, 1, 5, 10, and 20 A g−1, respectively) than pure MoS2 as well as admirable long‐term cycling characteristics (≈82% capacity retention after 20 000 cycles at 5 A g−1). Relevant kinetics mechanisms are expounded in detail. This work can be helpful for preparing other types of hybrid and flexible electrodes for energy storage systems.

CuO Nanoparticles/Multi-Walled Carbon Nanotubes (MWCNTs) Nanocomposites for Flexible Supercapacitors.

Copper oxide nanoparticles (CuO NPs)/multi-walled carbon nanotube (MWCNTs) nanocomposites were synthesized by a simple in-situ co-precipitation technique. MWCNTs networks acted as an ideal supporter for active material and permitted formation of free standing hybrid nanocomposite in the sheet form. Structural properties of CuONPs/MWCNTs nanocomposites were examined using X-ray diffraction (XRD), X-ray photon spectroscopy (XPS) and Transmission electron microscopy (TEM). By using three-electrode system, the electrochemical performance of the CuONPs/MWCNTs nanocomposite was investigated. The heat treated sample CuONPs/MWCNTs(H) yielded specific capacitance of 452.8 Fg-1 under 10 mV s-1 scan rate. Also, the nanocomposite exhibited good cyclic stability with 90% capacity retention over 500 charge-discharge cycles. This free-standing thin nanocomposite electrode can serve as a potential candidate as electrode for energy storage systems.

Vanadium Pentoxide Nanosheets in-Situ Spaced with Acetylene Black as Cathodes for High-Performance Zinc-Ion Batteries.

The 2D materials of ultrathin nanosheets possess plentiful active sites, effectively enhancing the electrochemical kinetics of various electrode materials. However, 2D materials usually suffer from the aggregation issue due to the strong van der Waals force of the individual nanosheets, leading to irreversible stacking and decreasing capacity. In this work, we develop a universal method to in-situ space the nanosheet cathodes for the electrodes of ZIBs. As a proof of concept, the V2O5 nanosheets with in-situ AB spacer were obtained, which were used as the cathode of aqueous ZIBs. Owing to plentiful active sites usable for electrolyte/electrode interfaces of the spaced V2O5, the ion diffusion kinetics of the electrodes would be enhanced. In contrast with the stacked V2O5, the spaced V2O5 delivers an exceptional specific capacity (452 mAh g-1), superior rate capability, and stable cycle life (the capacity retention of 92% after 5000 cycles). Moreover, the resultant ZIBs assembled with spaced V2O5 show an impressive energy/power density (158 Wh kg-1 at 19.3 kW kg-1). These superior electrochemical properties make the method of in-situ adding AB spacer hold promising potential to obtain advanced nanosheet electrodes for energy storage systems.

Structural, magnetic and electrochemical characterizations of Bi2Mo2O9 nanoparticle for supercapacitor application

In this present work, bismuth molybdate (Bi2Mo2O9) nanoparticles (NPs) were prepared by microwave combustion method using urea as the fuel. The phase formation and purity of the product was identified by powder X-ray diffraction (XRD). Fourier transform-infrared (FT-IR) analysis was adopted to record the functional group of Bi2Mo2O9 NPs. The morphology, purity, size and elemental composition of the sample were confirmed by Scanning electron microscope (SEM), elemental mapping, energy dispersive X-ray (EDX) analysis and High-Resolution transmission electron microscope (HR-TEM) technique respectively. The UV–visible and photoluminescence (PL) spectra were used to examine optical and electronic behavior of the prepared sample at room temperature (RT). The chemical bonding of Bi2Mo2O9 NPs was studied by Raman spectroscopy. The magnetic properties of Bi2Mo2O9 NPs were examined by vibrating sample magnetometer (VSM) at RT. The particle size distribution was examined by X-ray Photoelectron spectroscopy (XPS). The Electrochemical (EC) properties of Bi2Mo2O9 NPs were investigated by Cyclic voltammetry (CV), Galvanostatic charge/discharge (GCD) and Electrochemical impedance spectral (EIS) studies. The specific capacitance (Cs) of prepared Bi2Mo2O9 NPs is 197 F/g at 0.4 A/g with excellent cycle stability of 94% specific capacitance after 1000 cycles. Hence, the results of electrochemical characteristics exhibits excellent performance and have potential application of electrode for energy storage systems.

Morphology engineering of electro-deposited iron oxides for aqueous rechargeable Ni/Fe battery applications

Aqueous rechargeable Ni/Fe batteries possess potential advantages for large-scale energy storage applications due to their low cost, high safety and fast ion diffusions in electrolyte. However, the electrochemical performance of the iron-based anode is still far from ideal due to particle aggregations. Herein, we carry out the morphology engineering on the iron oxide active materials via a facile electrochemical method to improve its charge storage capability. The morphology transition from zero-dimensional particles to one-dimensional nanorods is realized by tuning the electrolyte composition, while subsequent annealing treatment results in further morphology modification into 3D interconnected nanoparticles (10–20 nm). The hierarchical structure allows facile ion and electron transfers, and the large surface provides various active sites for the charge storage conversion reaction. As a result, even at the high current density of 2 A g−1 (∼6C rate), the iron oxide electrode can still deliver a high specific capacity of 184 mAh g−1. At the same time, the morphology integrity and stability of the electrode leads to a good cycle life, with 87.5% capacity retained upon 5000 cycles. The Ni/Fe full cell assembled with the iron oxide anode and a Ni-Co double hydroxide cathode exhibits a good energy density of 82.3 Wh kg−1 at the power density of 3.3 kW kg−1. Our fundamental study would provide new insights for the electro-deposition of iron-based materials and endow new opportunities for the fabrication of high-performance iron-based electrodes for energy storage systems.