High-performance Energy Storage Applications Research Articles

Tuning the synergistic effects of MoS2and spinel NiFe2O4nanostructures for high performance energy storage and conversion applications

Energy storage and water splitting applications of MoS2/NiFe2O4nanocomposites are explored.

Cellulose nanofiber derived carbon aerogel with 3D multiscale pore architecture for high-performance supercapacitors.

Carbon materials are highly promising electrode materials for supercapacitors, due to their hierarchical porous structure and large specific surface area. However, the limited specific capacitance and inferior rate capability significantly prevent their practical application. Herein, 3D interconnected hierarchical porous carbon aerogels (CNFAs) through engineering the pyrolysis chemistry of CNF are developed. The obtained CNFAs effectively improve the carbon yield and suppress the volume shrinkage, as well as have robust mechanical properties. As a supercapacitor electrode, the CNFAs-17% electrode exhibits an ultrahigh capacitance of 440.29 F g-1 at 1 A g-1, significantly superior to most reported biomass-based carbon materials. Moreover, the CNFAs-17% assembled symmetric supercapacitor (SSC) achieves an outstanding rate capability (63.29% at 10 mA cm-2), high areal energy density (0.081 mWh cm-2), and remarkable cycling stability (nearly 100% capacitance retention after 7000 cycles). This work offers a simple, effective strategy towards the preparation of promising electrode materials for high-performance energy storage applications.

Constructing a hierarchically structured KNi0.67Co0.33PO4·H2O-graphene hydrogel/Ni foam electrode for superior all-solid-state supercapacitor.

A monolithic supercapacitor electrode of a KNi0.67Co0.33PO4·H2O-graphene composite hydrogel supported on Ni foam (KNCP-GH/NF) is first prepared by a one-step hydrothermal method, which achieves notable improvements in the electrode surface area and mass-loading of active materials. The KNCP-GH/NF electrode enjoys a hierarchical open-porous structure, where the KNCP-GH composite hydrogel fills in the voids in NF and the porous graphene hydrogel (GH) simultaneously provides a large support surface for growing active KNCP nanoflowers. Accordingly, the KNCP-GH/NF electrode exhibits a strikingly high capacity of 3240 mC cm-2 (876 C g-1) at 2 mA cm-2 and a satisfactory rate performance with 78.3% retention at 100 mA cm-2. Further, an all-solid-state asymmetric supercapacitor, constituted by using KNCP-GH/NF and Fe2P/GH/NF as the cathode and anode, respectively, and PVA-KOH as the solid-state gel electrolyte, delivers a high energy density of 69.2 W h kg-1 (3.9 mW h cm-3) and a power density of 13 229 W kg-1 (720 mW h cm-3) as well as notable cyclability with 81.2% capacity retention after 10 000 charge/discharge cycles. These attractive performances suggest a promising potential for a hierarchically structured KNCP-GH/NF electrode for the high-performance energy storage application.

Binary composites of nickel-manganese phosphates for supercapattery devices

This study demonstrates a cost-effective, facile and green synthesis of nickel-manganese (Ni-Mn) based binary metallic phosphates through a one-step sono-chemical method followed by calcination at 400 °C. The composites are further modified by changing the aspect ratio of Mn in Ni and utilized for high performance energy storage applications. The structure morphology of synthesized nanomaterials is investigated by performing X-ray diffraction (XRD) analysis. Among all, the composite with a concentration of Ni0.75:Mn0.25(PO4)2 exhibit the outstanding electrochemical performance by indicating high specific capacity (Qs) of 788.4 Cg−1 in three-electrode assembly. At last, the supercapattery is fabricated comprising of active material Ni0.75Mn0.25(PO4)2 as positive and activated carbon as negative electrode, which reveal exceptional results with a high specific energy and specific power of 64.2 Whkg−1 and 11,896 Wkg−1, respectively. This supercapattery device demonstrates excellent cyclic stability of 119% after 2000 continues GCD cycles. Our investigation reveals that the facile synthesis of these nanomaterials along with excellent electrochemical performance makes them valuable for the development of advanced high-performance energy storage devices.

Design and fabrication of cobalt and nickel ferrites based flexible electrodes for high-performance energy storage applications

In this work, to enhance supercapacitor research performance, we have prepared two different types of ferrites as CoFe2O4 and NiFe2O4 nanoparticles by two different routes, such as co-precipitation followed by hydrothermal method and facile hydrothermal method for the first time. In order to study the structural, morphological, and elemental composition of the fabricated ferrite electrodes, various characterization studies have been carried out, such as XRD, Raman, FESEM, EDS, HRTEM, BET, and XPS analysis. N2 adsorption–desorption results reveal that the hydrothermal assisted NiFe2O4 electrode shows a high surface area (109.3 m2/g) and pore size (43.4 nm) than compared with CoFe2O4 (78.5 m2/g and 21.2 nm). The electrochemical studies have been carried out for the electrodes using 1 M H2SO4 as electrolyte and graphite sheet as a current collector through three-electrode and two electrode systems, respectively. A maximum specific capacitance of 466 F g−1 at a current density of 1 A g−1 and 280 F g−1 at a current density of 0.5 A g−1 were obtained for the nickel ferrite nanoplates prepared via one-step hydrothermal method using three-electrode and two electrode systems, respectively. Moreover, the assembled symmetric NiFe2O4 supercapacitor delivers a high energy density (10 Wh Kg−1) at 0.5 A g−1 and power density (2500 W Kg−1) at a current density of 5 A g−1. Besides, the NiFe2O4 symmetric supercapacitor device exhibits 100% of specific capacitance retention sustained up to 10,000 cycles and 99% of Columbic efficiency.

Microsupercapacitor with a 500 nm gap between MXene/CNT electrodes

Abstract Decreasing the size of portable, wearable, and integrated electronics requires subsequent reduction in the accompanying energy storage devices. To further decrease the size of supercapacitors without compromising device performance, adequate materials are required as well as appropriate device design. Traditionally, carbon nanomaterials have been utilized within high-performance electrochemical energy storage applications, however carbides, specifically two-dimensional (2D) transition metal carbides and or nitrides (MXenes) have shown promise. Herein, a focused-ion-beam (FIB) process is used for patterning of titanium carbide (Ti3C2) carbon nanotube (CNT) electrodes into a finely controlled coplanar interdigitated configuration. The symmetric micro supercapacitors produced have a narrow, 500 nm gap between the electrode fingers and exhibit high areal capacitance of ~317 mF cm−2 at a scan rate of 50 mV s−1 and still retain >30% of their capacitance (~104 mF cm−2) at 100 V s−1. In addition, electron beam lithography and photolithography are utilized to create almost-invisible devices with ultra-small footprints (0.04 mm2 device areas) that can be used for securing electronic components. This study provides a simple and reliable method for fabrication of on-chip symmetric MSCs with coplanar interdigitated electrodes.

2D Sandwiched Nano Heterostructures Endow MoSe2 /TiO2- x /Graphene with High Rate and Durability for Sodium Ion Capacitor and Its Solid Electrolyte Interphase Dependent Sodiation/Desodiation Mechanism.

Nano heterostructures relying on their versatile construction and the breadth of combined functionality have shown great potential in energy storage fields. Herein, 2D sandwiched MoSe2 /TiO2- x /graphene nano heterostructures are designed by integrating structural and functional effects of each component, aiming to address the rate capability and cyclic stability of MoSe2 for sodium ion capacitors (SICs). These 2D nano heterostructures based on graphene platform can facilitate the interfacial electron transport, giving rise to fast reaction kinetics. Meanwhile, the 2D open structure induces a large extent of surface capacitive contribution, eventually leading to a high rate capability (415.2mAhg-1 @ 5Ag-1 ). An ultrathin oxygen deficient TiO2- x layer sandwiched in these nano heterostructures provides a strong chemical-anchoring regarding the products generated during the sodiation/desodiation process, securing the entire cyclic stability. The associated sodiation/desodiation mechanism is revealed by operando and ex situ characterizations, which exhibits a strong solid electrolyte interphase (SEI) dependence. The simulations verify the dependent sodiation products and enhanced heterostructural chemical-anchoring. Assembled SICs based on these nano heterostructures anode exhibit high initial Coulombic efficiency, energy/power densities, and long cycle life, shedding new light on the design of nano heterostructure electrodes for high performance energy storage application.

High energy density and high efficiency achieved in the Ca0.74Sr0.26Zr0.7Ti0.3O3 linear dielectric thin films on the silicon substrates

Linear dielectrics are promising candidates for high-performance energy storage applications with high efficiency, excellent thermal stability, and high reliability due to their low loss, high dielectric breakdown strength, and stable dielectric properties, which are independent of the electric field and temperature. However, their low dielectric constant or polarization restricts the stored electrical energy, which makes them less attractive for high energy density storage applications compared to relaxor ferroelectrics or anti-ferroelectrics. Here, we realized an ultrahigh energy density (Ue ∼ 59.4 J/cm3) and high efficiency (∼89%) simultaneously in the Ca0.74Sr0.26Zr0.7Ti0.3O3 (CSZT) linear dielectric thin film, which are competitive with those of other lead-based and lead-free dielectric films deposited on Si wafers. Moreover, the CSZT thin-film capacitor exhibits great thermal stability with the Ue variation less than 3% from −90 °C to 170 °C and good fatigue endurance with the Ue variation of 4.5% after 3 × 107 cycles at 10 kHz. This work also reveals that the exploration of advanced linear dielectric thin films with a medium dielectric constant would benefit from the development of high-performance energy-storage capacitors.

Boron-doped silicon carbide (SiC) thin film on silicon (Si): a novel electrode material for supercapacitor application

In this work, we report the synthesis of silicon carbide (SiC) thin film on silicon by modified chemical vapour deposition technique using boron-doped liquid polycarbosilane as a precursor. Subsequent microscopic and physical characterizations of this film show the presence of SiC nanocrystal along with boron in the SiC thin film. The electrochemical characterizations of the film shows a highest capacitance of 232F/g at 2.2A/g current density from Galvanostatic charging–discharging method with good cyclic stability upto 2000 cycles. The high capacitance value is attributed to the surface defect states and amorphous carbon which acts as the charge active sites. The result further infers that the (B)SiC/Si is a promising electrode material for high-performance energy storage application.

Intercorrelation between physical and electrochemical behavior of nitrogen-doping in graphene for symmetric supercapacitor electrode

Graphene and heteroatom-doped graphene are potential candidates for high-performance energy storage applications, such as supercapacitors. Herein, we have studied the structure and defect generation in nitrogen-doped reduced graphene oxide (N-rGO), synthesized via pyrolysis of urea in a wide temperature range (600–900 °C). Nitrogen-doped defect densities were analyzed in detail by the deconvolution of the Raman spectrum, where we found the importance of additional I and D’’ peaks. I peak is found to be sensitive to the dopant, and D” peak is consistent with the crystallinity, which are further revealed by X-ray photoelectron spectroscopy and X-ray diffraction measurements. Synthesized N-rGO was then investigated for the supercapacitor electrode. N-rGO synthesized at 800 °C, having low crystallinity (crystallite size 3.44 nm), highest degree of reduction (C/O ratio = 23), high specific surface area (152.3 m2 g−1), and presence of both pseudocapacitive and electric double layer behavior, resulting in highest areal capacitance of 138.4 mF cm−2, lowest self-discharge rate, and exceptional capacity retention of 121.7% after 10,000 cycles of charge–discharge. The synthesized electrode material has also been tested for a symmetric supercapacitor cell showing high specific capacitance 66.8 F g−1 in 0.5 M H2SO4 electrolyte. This study is a first of its kind of structural evaluation and Raman characterization of N-rGO for application in supercapacitor cell.

Cubic nanostructure of Co3O4@nitrogen doped graphene oxide/polyindole composite efficient electrodes for high performance energy storage applications

In this study, Co3O4@NGO/polyindole composites were synthesized using ultrasonication followed by hydrothermal processes. The structure and morphology of composites were investigated by analytical techniques such as Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy, X-ray diffraction analysis (XRD), X-ray photo electron spectroscopy (XPS), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HR-TEM) and Brunauer–Emmett–Teller (BET) surface analysis. The electrochemical performances of the composites were studied by cyclic voltammetry (CV), galvanostatic charge discharge (GCD)and electrochemical impedance spectroscopy analysis (EIS) measurements. As a proof of concept demonstration we have employed Co3O4@NGO/polyindole (PIN) as an electrode in supercapacitor. The Co3O4@NGO/PIN composite showed a capacitance of ∼680Fg−1 at 0.5Ag−1 and had an excellent cycling stability of 96% after 5000 cycles at 0.5Ag−1 indicating the material as a potential candidate in supercapacitor applications.

Development of vertically aligned trimetallic Mg-Ni-Co oxide grass-like nanostructure for high-performance energy storage applications

Direct growth of nanostructured trimetallic oxide on substrate is considered as one of the promising electrode fabrication for high-performance hybrid supercapacitors. Herein, binder-free one-dimensional grass-like nanostructure was constructed on nickel foam by using electrodeposition approach. The admirable enhancement in rate capability was observed by the substitution of Mg and Ni in cobalt oxide crystallite. The prepared nickel cobalt oxide (NCO) and cobalt oxide (CO) electrode exhibited a rate capability of 57% and 58% (2 to 10 A g−1) respectively. Interestingly, the rate capability was increased to 87% by the substitution of Mg and Ni simultaneously. The novel vertically aligned trimetallic Mg-Ni-Co oxide (MNCO) grass-like nanostructure electrode exhibited a high specific capacity of 846 C g−1 at 2 A g−1, retained 97.3% specific capacity and showed an outstanding coulombic efficiency of 99% after 10,000 charge–discharge cycles. Moreover, we assembled hybrid supercapacitor (HSC) device for practical applications by using MNCO and activated carbon (AC) as the positive and negative electrode materials, respectively. HSC device exhibited a high specific capacity of 144 C g−1 at 0.5 A g−1. The high energy density of 31.5 Wh kg−1 and the power density of 7.99 kW kg−1 were achieved. All these interesting and attractive results demonstrate the significance of the vertically aligned electrode material towards practical applications.

Quantification of Dead Lithium via In Situ Nuclear Magnetic Resonance Spectroscopy

Summary Inhomogeneous lithium deposition or dendrite formation and occurrence of “dead lithium” fractions are challenging issues, hampering the commercial application of lithium metal batteries. Conditions and strategies for minimizing potential failure of lithium metal anodes are currently not fully understood, despite recent progress. We report a protocol utilizing in situ and ex situ 7Li solid-state NMR spectroscopy to quantify irreversible lithium losses in batteries, clearly distinguishing losses due to SEI formation and fractions of “dead lithium,” revealing a distribution of different lithium metal microstructures on both working and counter electrodes upon plating and stripping. Estimates of dead lithium fractions of 3.3% ± 0.6% (with 5% FEC) and 9.4% ± 0.6% (without 5% FEC) are determined. The proposed protocol affords benchmarking of commercial cells, including future design of suitable strategies for effective development and tailoring of electrolyte formulations, fostering further advancement of high-performance energy storage applications.

Reagents assisted Mg-doped CeO2 for high-performance energy-storage applications

Abstract A novel Mg-doped CeO2 electrode materials were prepared by simple and cost effective hydrothermal method by using three different reagents (ammonium fluoride, potassium hydroxide and hexamethylenetetramine). Successful preparation was confirmed by using various characterizations. In three electrode setup, CeO2: Mg-NH4F, CeO2: Mg-KOH, and CeO2: Mg-HMTA showed a high specific capacitance of 432, 275 and 221 F g−1 at 1 A g−1 respectively. After 10,000 continuous cycles of charging and discharging, only 11% fade in the specific capacitance was observed for CeO2: Mg-NH4F. Moreover, CeO2: Mg-NH4F was used as a positive electrode and (activated carbon) AC as a negative electrode for asymmetric supercapacitor (ASC) device. The highest specific capacity of 130C g−1 at 1 A g−1 was obtained for ASC device. ASC device delivered a high energy density of 28.8 Wh kg−1 at a power density of 775 W kg−1. ASC device showed an excellent retention of 83% and an outstanding coulombic efficiency of 99% after 9000 cycles. All these attractive results suggest the importance of this electrode material towards practical applications.

Oxygen vacancies boosting ultra-stability of mesoporous ZnO-CoO@N-doped carbon microspheres for asymmetric supercapacitors

Long-term cycling stability of pseudocapacitive materials is pursued for high-energy supercapacitors. Herein, the mesoporous zinc-cobalt oxide heterostructure@nitrogendoped carbon (ZnO-CoO@NC) microspheres with abundant oxygen vacancies are self-assembled through a hydrothermal method combined with an annealing post-treatment. The multifunctional polyvinyl pyrrolidone (PVP) is used as a structure-directing agent, the precursor of NC and the initiator of abundant oxygen vacancies in zinc-cobalt oxide microspheres. XPS demonstrates the generation of surface oxygen vacancies resulted from the reduction effect of conductive NC, and further confirms the weaker interaction between the metal ions and oxygen atoms. As a result, the electrode based on ZnO-CoO@NC in 2 mol L−1 KOH shows enhanced capacitive performance with an excellent cycle stability of 92% retention of the initial capacitance after 40,000 charge-discharge cycles at 2 A g−1, keeping the morphology unchanged. The assembled asymmetric supercapacitor, graphene//ZnO-CoO@NC, also performs good cyclic stability with 94% capacitance retention after 10,000 cycles at 2 A g−1. The remarkable electrochemical performance of the self-assembled ZnO-CoO@NC composite is attributed to the mesoporous architecture, abundant oxygen vacancies, conductive ZnO scaffold for CoO crystals forming heterostructure of ZnO-CoO and the high conductive NC layer covering outside of the multi-metal oxide nanoparticles. Hence, the ZnO-CoO@NC holds great promise for high-performance energy storage applications.

SnS2-gC3N4/rGO Composite Paper as an Electrode for High-Performance Flexible Symmetric Supercapacitors

The flexible, free-standing, durable SnS2-gC3N4/rGO paper material was prepared by vacuum filtration of the composite dispersion containing GO and the SnS2-gC3N4 composite structure which is synthesized by a simple hydrothermal method. The as-prepared SnS2-gC3N4/GO composite paper was converted to SnS2-gC3N4/rGO paper material by applying a chemical reduction process. SnS2-gC3N4/rGO paper material was characterized by using FESEM, XRD, Raman, XPS, and EIS spectroscopy techniques. The SnS2-gC3N4 composite, a porous flower-like structure, uniformly intercalated between the graphene nanosheets exhibited excellent mechanical stability, greatly improved active surface areas, and enhanced surface porosity, in comparison with the pristine rGO paper. SnS2-gC3N4/rGO composite paper material show a highest specific capacitance of 532 F g-1 at 1 A g-1 and good cycling stability with capacitance retention of 60 % at 4 A g-1 after 5000 cycles. Moreover, SnS2-gC3N4/rGO composite paper demonstrate an excellent supercapacitor performance compared to the gC3N4/rGO paper and pristine rGO paper. The flexible symmetric supercapacitor based on SnS2-gC3N4/rGO composite electrode exhibits remarkable mechanical flexibility, high capacitive performance (403 F g-1 at 1 A g-1) and high cycle stability (63.8% at 4 A g-1 after 1500 cycles). As a result, SnS2-gC3N4/rGO composite paper material is expected to be a promising material for high-performance energy storage applications.

Two-Dimensional Layered Metallic VSe2 /SWCNTs/rGO Based Ternary Hybrid Materials for High Performance Energy Storage Applications.

In this work, the ternary hybrid structure VSe2 /SWCNTs/rGO is reported for supercapacitor applications. The ternary composite exhibits a high specific capacitance of 450 F g-1 in a symmetric cell configuration, with maximum energy density of 131.4 Wh kg-1 and power density of 27.49 kW kg-1 . The ternary hybrid also shows a cyclic stability of 91 % after 5000 cycles. Extensive density functional theory (DFT) simulations on the structure as well as on the electronic properties of the binary hybrid structure VSe2 /SWCNTs and the ternary hybrid structure VSe2 /SWCNTs/rGO have been carried out. Due to a synergic effect, there are enhanced density of states near the Fermi level and higher quantum capacitance for the hybrid ternary structure compared to VSe2 /SWCNTs, leading to higher energy and power density for VSe2 /SWCNTs/rGO, supporting our experimental observation. Computed diffusion energy barrier of electrolyte ions (K+ ) predicts that ions move faster in the ternary structure, providing higher charge storage performance.

The positive effect of nitridation on CrNb49O124 nanowires for high-performance lithium-ion storage

Advanced electrode materials with excellent electrochemical properties have always been widely concerned in lithium-ion batteries (LIBs). In this work, two kinds of CrNb49O124 nanowires of different sizes are prepared via electrospinning technique with two different solvents (ethanol and dimethylformamide). Moreover, the obtained CrNb49O124 nanowires are nitrided by thermal ammonia gas to further improve the electrochemical performance. And it is pleasantly surprised to say that the nitrided CrNb49O124 nanowires perform better than our expectation. It exhibits an initial Coulombic efficiency up to 90.72%, and an eximious charge specific capacity (273.6 mAh g−1), which is apparently higher than that before nitridation. In addition, after 300 cycles at 1 C, it still maintains capacity of 224.4 mAh g−1 and the retention is up to 90.41%, indicating its excellent long cycling stability. The outstanding electrochemical properties of nitrided CrNb49O124 nanowires are proved to be much superior than most of anode materials in LIBs. Meanwhile, it is successfully confirmed that nitridation technique can be an efficient approach for high-performance energy storage applications to promote electrochemical properties of most electrode materials.

High yield conversion of biowaste coffee grounds into hierarchical porous carbon for superior capacitive energy storage

Recently great efforts have been focused on converting biowastes into high-valued carbon materials. However, it is still a great challenge to achieve high carbon yield and controllable porous distribution in both industrial and academic research. Inspired by the multi-void structure of waste coffee grounds, herein we fabricated hierarchical porous carbon via the combination of catalytic carbonization and alkali activation. The catalytic carbonization process was applied to obtain well-defined mesoporous carbon with carbon yield as high as 42.5 wt%, and subsequent alkali activation process produced hierarchical porous carbon with ultrahigh specific surface area (3549 m2 g−1) and large meso-/macropores volume (1.64 cm3 g−1). In three-electrode system, the electrode exhibited a high capacitance of 440 F g−1 at 0.5 A g−1 in 6 M KOH aqueous electrolyte, superior to that of many reported biomass-derived porous carbons. In two-electrode system, its energy density reached to 101 Wh kg−1 at the power density of 900 W kg−1 in 1-Ethyl-3-Methylimidazolium Tetrafluoroborate (EMIMBF4). This work provided a cost-effective strategy to recycle biowastes into hierarchical porous carbon with high yield for high-performance energy storage application.

Carbon-Based Polymer Nanocomposite for High-Performance Energy Storage Applications.

In recent years, numerous discoveries and investigations have been remarked for the development of carbon-based polymer nanocomposites. Carbon-based materials and their composites hold encouraging employment in a broad array of fields, for example, energy storage devices, fuel cells, membranes sensors, actuators, and electromagnetic shielding. Carbon and its derivatives exhibit some remarkable features such as high conductivity, high surface area, excellent chemical endurance, and good mechanical durability. On the other hand, characteristics such as docility, lower price, and high environmental resistance are some of the unique properties of conducting polymers (CPs). To enhance the properties and performance, polymeric electrode materials can be modified suitably by metal oxides and carbon materials resulting in a composite that helps in the collection and accumulation of charges due to large surface area. The carbon-polymer nanocomposites assist in overcoming the difficulties arising in achieving the high performance of polymeric compounds and deliver high-performance composites that can be used in electrochemical energy storage devices. Carbon-based polymer nanocomposites have both advantages and disadvantages, so in this review, attempts are made to understand their synergistic behavior and resulting performance. The three electrochemical energy storage systems and the type of electrode materials used for them have been studied here in this article and some aspects for example morphology, exterior area, temperature, and approaches have been observed to influence the activity of electrochemical methods. This review article evaluates and compiles reported data to present a significant and extensive summary of the state of the art.