High Energy Storage Capability Research Articles

Phase change material filled hybrid 2D / 3D graphene structure with ultra-high thermal effusivity for effective thermal management

Graphene-based energy storage and renewable material has increasingly attracted research interest, due to its high thermal conductivity and light weight. Researchers fill phase change material (PCM) into three-dimensional graphene foam, to obtain a composite with high energy storage capability and moderate thermal conductivity. However, heat transfer mode of this kind of composite is single and cannot maximize the advantages of graphene. Herein, a stearic acid filled graphene-foam composite (GFSAC) connected with graphene paper (GP) through gravity-assisted wetting attaching process is demonstrated. The GP/GFSAC/GP composite possesses a high thermal conductivity of 1.72 Wm−1K−1 (with 0.53 wt % graphene loading), and an excellent effective thermal effusivity of 18.45 Jcm−3/2m−1/2s−1/2K−1/2. The GP/GFSAC/GP composite is shown to be an ideal material for thermal energy storage and renewable. Additionally, the low thermal resistance connection is achieved between 3D GFSAC and 2D GP, which plays a key role in the improvement of the composite’s thermal effusivity. Compared to other samples, the maximum temperature of the GP/GFSAC/GP composite is significantly lower and its temperature uniformity is much better, under the same heating condition. More importantly, after stop heating, the GP/GFSAC/GP composite shows the best temperature maintenance capacity.

Tuning the microstructure of BaTiO3@FeO core-shell nanoparticles with low temperatures sintering dense nanocrystalline ceramics for high energy storage capability and stability

A BaTiO3@FeO nanoceramic was successfully fabricated by chemical coating technique under sintering and achieved high energy storage capability. The FeO layer was coated onto BaTiO3 nanoparticles by sol-precipitation method. The structures, dielectric properties and energy storage capability of ceramics were systematically investigated. A high densification and nano-scale crystalline were observed after low temperatures sintering by this chemical coating technology and the grain size maintained about 70 nm. This chemical coating method is contributed to obtain dense nanocrystalline ceramics, benefiting to enhance the breakdown strength and energy storage density. The dielectric properties of BaTiO3@%FeO nanoceramics exhibit good temperature (−55 to 125 °C) and frequency(1 Hz–1 MHz) stability, indicating the fine dielectric quality of the ceramics. The BaTiO3@3%FeO nanoceramics present a high discharge energy storage density of 1.50 J cm−3 at 300 kV/cm-1 with a high energy storage efficiency about 88%. Moreover, the advanced energy storage properties with fast discharge features (τ0.9< 1.5 μs), prominent thermal stability (25–120 °C) and high cyclic stability (up to 1 × 105 times) were achieved in the BaTiO3@FeO nanoceramic. This nanoceramic prepared via the chemical coating could be a potential material for energy storage capacitor application.

Low electric field induced high energy storage capability of the free-lead relaxor ferroelectric 0.94Bi0.5Na0.5TiO3-0.06BaTiO3-based ceramics

Morphotropic phase (MPB) eco-friendly ferroelectric 0.94Bi0.5Na0.5TiO3- 0.06BaTiO3 (NBT-BT) ceramics exhibits superior piezoelectric performances. However, the large remnant polarization (Pr) and low breakdown strength (Eb) of NBT-BT systems hinders application in energy storage capacitors. Herein, the Bi(Zn1/3Nb2/3)O3 (BZN) is selected to partially replace the NBT-BT ceramics to break ferroelectric long-range order domains achieving higher energy storage properties. Highly recoverable energy storage density (Wrec ~ 3 J/cm3) and efficiency (η ~ 75%) are acquired in (NBT-BT)-0.06BZN ceramics under a low applied electric field of 210 kV/cm. Furthermore, superior temperature stability (20–120 °C), and frequency (1–1000 Hz) stability, and fatigue endurance (105 st) are also gained. These advantages further suggest that the (NBT-BT)-0.06BZN ceramics exhibit great promise in pulsed power markets.

Preparation of phase change material filled hybrid 2D/3D graphene structure with ultra-high thermal effusivity for effective thermal management

Graphene-based energy storage and renewable material has increasingly attracted research interest, due to its high thermal conductivity and light weight. Researchers fill phase change material (PCM) into three-dimensional graphene foam, to obtain a composite with high energy storage capability and moderate thermal conductivity. However, this kind of composite's heat transfer mode is single and cannot maximize the advantages of graphene. Herein, a stearic acid filled graphene-foam composite (GFSAC) connected with graphene paper (GP) through gravity-assisted wetting attaching process is demonstrated in this paper.•GP is obtained by thermal reduction of graphene oxide (GO) paper. Its in-plane thermal conductivity can reach up to 938 Wm−1 K−1. By controlling the preparation process of GO paper, the in-plane thermal conductivity of GP can be adjusted.•GFSAC is consisted of GF and SA, GFSAC with different heat transfer properties can be prepared by adjusting the degree of reduction of GF.•A novel gravity-assisted wetting attaching process has been developed to prepare GP/GFSAC/GP composite, which can effectively reduce the thermal resistance between GP and GFSAC.The effective thermal effusivity of the final GP/GFSAC/GP composite reaches 18.45 J cm−3/2 m−1/2 s−1/2 K−1/2, showing an excellent thermal management capability.

Heteroarchitecturing a novel three-dimensional hierarchical MoO2/MoS2/carbon electrode material for high-energy and long-life lithium storage

A three-dimensional hierarchical MoO2/MoS2/C heterostructure has been engineered through a facile polymerization–carbonization strategy, which demonstrates high-energy and long-life lithium storage capability as an anode material.

All‐solid‐state supercapacitors based on yarns of Co3O4-anchored porous carbon nanofibers

Developing an efficient all‐solid‐state structural supercapacitor with simultaneous high energy storage and load-bearing capabilities for reducing weight/volume in weight-/weight-restricted applicationsremains challenging. Relying only on the solemechanismof theelectrical double layerand the existing trade-offs between load bearing and energy storage requirements have limited the overall performance of carbon-based structural electrodes. Herein, we describe the development of ultrafineCo3O4-anchored highly-porous, hollow, N-doped carbon nanofiber yarns (Co-NCFY) asa high performance multifunctional structural electrode with a remarkable performance index representing mechanical and electrochemical properties. The device is designed to benefit from both the pseudocapacitance and double layer mechanisms to store energy. The Co-NCFY show promising electrochemical properties (electrochemical capacity of 713 F g−1at 1 mV s−1, desirable cycling stability of >92% at 20 A g−1 after >8000 cycles, energy density of 45.4 Wh kg−1 at a power density of 209 W kg−1), and load-bearing capability (strength and young modulus of 87.4 MPa and 26.4 GPa, respectively). Taking into account both electrochemical and mechanical properties, the Co-NCFY outperform recently reported structural electrode materials (see Ashby chart in graphical abstract). These attractive attributes make Co-NCFY a unique structural electrode material for efficient structural energy storage devices.

Electrochemical performance of coin cell-type symmetric supercapacitor electrode consisting of three-dimensional molybdenum disulfide microflowers

Three-dimensional MoS2 (3D-MoS2) microflowers consisting electrode of few-layered nanoflakes synthesized via a hydrothermal approach is a promising material for ultrahigh-performance symmetric supercapacitors. A three-electrode configuration of the 3D-MoS2 microflowers exhibited a remarkable electrolytic specific capacitance of 243.31F g−1 at 0.5 A g−1 and 98.71% retention after 2000 charge/discharge sequences at 8 A g−1. The fabricated coin cell-type symmetric supercapacitor devices (SSDs) showed an ultrahigh power density (Pd) of 2412.15 W Kg−1 at an energy density (Ed) of 1.06 Wh Kg−1, exhibiting the high energy storage capability of the 3D-MoS2 microflowers, thus enabling their application to electrodes in hybrid energy storage devices.

Electroactive organically modified mesoporous silicates on graphene oxide-graphite 3D architectures operating with electron-hopping for high rate energy storage

Pseudo-capacitive materials operating with electron-hopping as the charge transfer mechanism are elaborated by the extensive assembly of fixed redox molecules onto the surface of graphene-supported mesoporous silica film. Various physico-chemical techniques are used to characterize the resulting composites. The obtained GO@Fc-MS electrode (ferrocene functionalized silica film coated onto electro-exfoliated graphene) can deliver a specific capacity of 196 mC cm−2 (326 mF cm−2) at a current density of 2 mA cm−2 and a 69% capacity retention even at 3800 C, which is much better than the traditional faradic materials. The electrochemical analyses reveal the energy storage behavior of GO@Fc-MS is a fast surface-controlled redox process. The electrode can be assembled into an asymmetric device which exhibits excellent cycling stability (no noticeable fading after 10 000 cycles) and competitive energy densities (respectively 17.7 or 9.2 µWh cm−2 at power densities of 0.53 or 13.7 mW cm−2). These results open up new opportunities for pseudocapacitive materials based on electroactive inorganic frameworks bearing surface-tethered molecular redox sites with high energy storage capability.

Hierarchically hollow NiCo2S4/graphitic nanofiber film with ultrahigh-rate capability and long-term cycling durability for asymmetrical supercapacitor

NiCo2S4 nanostructures have been intensively investigated as supercapacitor electrode materials ascribing to its high conductivity and capacity. However, NiCo2S4-based electrodes suffer inferior cycling durability owing to its structural degradation during the redox process. Herein, NiCo2S4 nanoneedles anchored on the graphitic carbon nanofiber mat (NiCo2S4/GCN) are synthesized via a two-pot hydrothermal method. The NiCo2S4/GCN composed of highly conductive graphitic carbon nanofiber (GCN) frameworks ensures the uniform dispersion of NiCo2S4 and accelerate electron/ion transport, and NiCo2S4 with porous and hollow nanostructure facilitates the diffusion of electrolyte. The NiCo2S4/GCN electrode reveals a high-energy storage capability (1775.2 F g−1 at 10 A g−1) and an amazing rate retention (1510.2 F g−1 at 50 A g−1). Furthermore, the NiCo2S4/GCN//active carbon device displays a superior energy density (52.3 W h kg−1 at 358.0 W kg−1) and preeminent cycle life (retention 94.7% after 10,000 cycles at 5 A g−1), suggesting a promising candidate in supercapacitor applications.

High energy storage and ultrafast discharge in NaNbO3-based lead-free dielectric capacitors via a relaxor strategy

Dielectric capacitors with decent energy storage and fast charge-discharge performances are essential in advanced pulsed power systems. In this study, novel ceramics (1-x)NaNbO3-xBi(Ni2/3Nb1/3)O3(xBNN, x = 0.05, 0.1, 0.15 and 0.20) with high energy storage capability, large power density and ultrafast discharge speed were designed and prepared. The impedance analysis proves that the introducing an appropriate amount of Bi(Ni0·5Nb0.5)O3 boosts the insulation ability, thus obtaining a high breakdown strength (Eb) of 440 kV/cm in xBNN ceramics. A high energy storage density (Wtotal) of 4.09 J/cm3, recoverable energy storage density (Wrec) of 3.31 J/cm3, and efficiency (η) of 80.9% were attained in the 0.15BNN ceramics. Furthermore, frequency and temperature stability (fluctuations of Wrec ≤ 0.4% over 5–100 Hz and Wrec ≤ 12.3% over 20–120 °C) were also observed. The 0.15BNN ceramics exhibited a large power density (19 MW/cm3) and ultrafast discharge time (~37 ns) over the range of ambient temperature to 120 °C. These enhanced performances may be attributed to the improved breakdown strength and relaxor behavior through the incorporation of BNN. In conclusion, these findings indicate that 0.15BNN ceramics may serve as promising materials for pulsed power systems.

Preparation of mulberry-like RuO2 electrode material for supercapacitors

As a newly emerging excellent energy storage device, supercapacitors have been widely studied due to their unique advantages. Electrode material is one of the key components that determine the performance of a supercapacitor. Among the various electrode materials of supercapacitors, RuO2 has attracted great attention in the scientific community due to its high theoretical energy storage capability and excellent stability. However, most RuO2 materials suffer the problem of low specific surface area, causing a much lower actual capacitance value compared to the theoretical performance of the material. In this work, a mulberry-like RuO2 electrode material with large specific surface area (159.4 m2·g−1) was successfully synthesized by a facial hydrothermal method. The electrochemical characterization has shown that the RuO2 possesses a high specific capacitance of 400 F·g−1 at a current density of 0.2 A·g−1 and good capacitance retention rate of 84.7% after 6000 charge/discharge cycles under a current density of 10 A·g−1. The energy densities and power densities of the RuO2-AC supercapacitor vary from 25.0 to 11.7 Wh·kg−1 and 160 to 10,560 W·kg−1 at current density ranging from 0.2 to 10.0 A·g−1, respectively.

Improved preparation of MoS2/graphene composites and their inks for supercapacitors applications

This paper presents a new and facile method to prepare molybdenum disulfide (MoS2)/graphene composites and their inks based on an improved ball milling process. The developed method is cost effective, environmentally friendly, and scalable, producing few-layer MoS2 material and MoS2/graphene-based inks. The prepared inks after characterization by SEM, Raman, XRD, FTIR, CA and rheology were used to fabricate electrodes for supercapacitorsby adopting twodesigns: 2D printed and sandwiched electrodes. The electrodes showed excellent electrochemical performance with a specific capacitance of 392 Fg−1 at 5 mV s−1 and low equivalentresistance of 0.41 Ω, which outperforms the properties of graphene electrodes. The specific capacitance of electrodes prepared by 2D printing using MoS2/graphene ink was 76 Fg−1 at 5 mV s−1 with an areal capacitance of 58.5 mF/cm−2 at 0.77 mg/cm−2, demonstrating high energy storage capability. The performance of the MoS2/graphene composites and their inks highlights their promising application as electrode materials for high-performance energy storage devices.

Oxide-based cathode materials for rechargeable zinc ion batteries: Progresses and challenges

The working mechanisms, cathode design, recent progress and challenges of oxide-based cathodes for zinc ion batteries (ZIBs) are systematically reviewed. With the increasing demands for electrical energy storage technologies, rechargeable zinc ion batteries (ZIBs) have been rapidly developed in recent years owing to their high safety, low cost and high energy storage capability. The cathode is an essential part of ZIBs, which hosts zinc ions and determines the capacity, rate and cycling performance of the battery. The mainstream cathodes for ZIBs are oxide-based materials with tunnel, layer or 3D crystal structures. In this review, we mainly focus on the latest advanced oxide-based cathode materials in ZIBs, including manganese oxides, vanadium oxides, spinel compounds, and other metal oxide based cathodes. In addition, the mechanisms of zinc storage and recent development in cathode design have been discussed in detail. Finally, current challenges and perspectives for the future research directions of oxide-based cathodes in ZIBs are presented.

Flexible, Thin-Layer Solid-State Supercapacitor Based on V2O5-Graphene Composite Electrode and Ionic Liquid Gel Polymer Electrolyte for Portable Electronic Systems

Electrochemical and energy storage properties of vanadium oxide-graphene composite electrode based solid state supercapacitor using ionic liquid gel electrolyte over flexible stainless-steel foil substrates are discussed. The composite electrode was deposited by a simple technique of spin coating of nano-size graphene dispersed vanadium sol gel followed 300°C -6h air annealing. Graphene mitigates the low electrical resistance limitation of faradaic V2O5 while contributing double layer capacitance to the overall pseudocapacitance. The BMIMBF4 ionic liquid gel with 0.2M LiClO4 dopant acts as high ionic conductivity electrolyte and source of counter ions for redox reactions. The flexible symmetrical V2O5/graphene supercapacitor shows high specific capacitance of 650 Fg-1 and energy and power density values of 30 Wh.kg-1 and 3kW kg-1, respectively at charging potential of 1.5V. The linear charge-discharge, high Coulomb efficiency ~90% and low internal resistance support its use as power source for portable electronics with high energy storage capability.

Additive Functionalization and Embroidery for Manufacturing Wearable and Washable Textile Supercapacitors

AbstractElectronic textiles require rechargeable power sources that are highly integrated with textiles and garments, thereby providing outstanding durability and washability. In contrast, present power sources fabricated using conventional ex situ strategies are difficult to integrate with clothing and can degrade during garment washing. Here, a new manufacturing strategy named additive functionalization and embroidery manufacturing (AFEM) is reported, which enables textile‐based supercapacitors (TSCs) to be directly fabricated on woven, knitted, and nonwoven fabrics. The additive principle of AFEM allows developing TSCs with different types of electrode materials, device architectures, pattern designs, and array connections. High‐machine‐speed, programmable‐design industrial embroidering equipment is used to fabricate TSCs with high areal energy storage and power capabilities, which are retained during many cycles of severe mechanical deformation and industrial laundering with waterproof encapsulation.

WITHDRAWN: Flexible, Thin-Layer Solid-State Supercapacitor Based on V2O5-Graphene Composite Electrode and Ionic Liquid Gel Polymer Electrolyte for Portable Electronic Systems

This abstract has been withdrawn at the request of the authors.

(Invited) Nasicon-Type NaV2(PO4)3 As a Cathode Material for Calcium-Ion Batteries

Li-ion batteries (LIBs) have been the most prevailing rechargeable batteries for the last three decades. However, the present LIBs have energy densities close to the theoretical limits, and the Li resources are scarce. Calcium-ion batteries (CIBs) are one of the promising candidates to overcome such limitations of LIBs. The divalency of calcium as the carrier ion can increase the capacity of a host material because two electrons are transferred per carrier ion. The earth-abundance of calcium resources provides potential cost-effectiveness to the products. Calcium has the redox potential (Ca/Ca2+ = −2.87 V vs. SHE) close to Li, potentially leading to a higher cell operating voltage. Calcium ion also has a relatively low effective intercalant-ion charge density (0.49 e/Å3), compared to other multivalent cations such as Mg2+ (1.28 e/Å3), Zn2+ (1.18 e/Å3), and Al3+ (4.55 e/Å3), enabling fast diffusion kinetics for Ca ions in solids as well as in electrolytes. Recent discoveries of reversible plating or alloying of calcium provoked considerable interest in calcium-based rechargeable batteries. Theoretical calculations also predict that the energy barriers for Ca diffusion are lower than other multivalent ions in some structures, and the development of positive materials are anticipated. However, only a few positive materials have been reported so far, only to exhibit low energy-storage capability and poor cyclability. In this work, we report NASICON-type NaV2(PO4)3 as a cathode material for nonaqueous CIBs, with high capacity and voltage with a good cyclability. This work demonstrates experimentally that an oxide material can be a good host structure for Ca diffusion at room temperature with high energy-storage capability.

Tunable dielectric polarization and breakdown behavior for high energy storage capability in P(VDF-TrFE-CFE)/PVDF polymer blended composite films.

Polymer dielectrics with high dielectric performances and superior discharge energy capability are highly desirable for advanced electrostatic capacitor applications. However, the paradoxical relationship between dielectric polarization and electric breakdown behavior generally hinder their further enhancement in energy storage performances. Herein, polymer blended composite films with high energy storage capability were successfully fabricated by blending together poly(vinylidene fluoride) (PVDF) polymer and poly(vinylidene fluoride-trifluoroethylene-chlorofluoroethylene) (P(VDF-TrFE-CFE)) terpolymer. The P(VDF-TrFE-CFE) terpolymer has a high dielectric constant to provide a large electric displacement under an applied electric field far below its breakdown field, which is anticipated to modulate the dielectric polarization behavior of PVDF polymer when blended in different proportions. Consequently, the polymer blended composite film consisting of 20 wt% (P(VDF-TrFE-CFE)) terpolymer exhibits a high discharge energy density of 13.63 J cm-3 at an enhanced breakdown strength of 480 MV m-1. This obtained high discharge energy density is 84% higher than the pure PVDF film and 582% higher than a commercialized biaxially oriented polypropylene (BOPP). Large interfacial polarization and strong interaction of polymer chains between the PVDF polymer and P(VDF-TrFE-CFE) terpolymer may contribute to the tunable dielectric constant and electric breakdown strength, thus promoting the energy storage capability. This work establishes a facile, but effective approach to achieve the high energy storage capability of PVDF polymer-based flexible composite films for capacitive energy storage applications.

Self-Standing N-Doped Inverse Opal Carbon via Ultrafast Polymerization of Polydopamine and its High Energy Storage Capability in Li–O2 Batteries

3D ordered N-doped carbon with an inverse opal nanostructure (cPDA-IO) is synthesized by the carbonization of polydopamine using self-assembled polystyrene as a template. The inverse opal structure...

Tailoring of Liquid Electrolytes for Room-Temperature Fluoride Shuttle Batteries

Fluoride ion shuttle batteries (FSBs), alternatively referred to as fluoride ion batteries (FIBs), are anion-based rechargeable batteries with fluoride (F-) ions as charge transporting and redox active species, and potentially offer a high electrochemical energy storage capability that overwhelms those of the state-of-the-art lithium ion batteries. The theoretical gravitational capacities for some typical metal/fluoride combinations, e.g., Ag/AgF, Cu/CuF2, Bi/BiF3, and Al/AlF3, amount to 249, 844, 385, and 2980 mAh/g, respectively. Nevertheless, despite some considerable efforts in the past decade or so, FSBs are still far from practical, because of a number of technical limitations to overcome no matter which type of FSB, all-solid type or liquid type, is of major interest. In particular, liquid-electrolyte based FSBs suitable for room-temperature cell operation require high-quality fluoride ion transporting electrolytes ensuring both high enough reactivity of the fluoride ions with the active material of interest and sufficient electrochemical stability of the electrolyte as a whole. Unfortunately, normally none of alkali fluorides are soluble in whatever high boiling battery-oriented organic solvents. One way to solve this problem has been to use organic fluoride salts. Another sophisticated way out has been to utilize a so-called anion acceptor (AA) that makes alkali fluorides substantially soluble even in low polarity solvents such as the glyme series. AA can also play another important role to facilitate the dissolution and re-deposition of the active materials into and from the electrolyte, which are unique pathways available in liquid-electrolyte based FSBs. However, the overall cell performances so far reported in the literature are still limited in capacity and cyclability. In this paper, we introduce lactone-based liquid electrolytes tailored for room-temperature FSBs, where either CsF or KF is dissociated without the help of any special addenda to offer strong electrolytes. Although the maximum fluoride ion concentration achieved by this method is around 0.05 M, it affords the ionic conductivity more than 0.5 mS/cm and the fluoride ions transported between the cathode and anode exhibit high reactivity with various metals to sustain reversible redox reactions to and from their fluoride counterparts. We have also achieved some successful battery operations using practical polymer-composite electrodes. Together with a superior cyclability, the thus tailored liquid fluoride electrolytes offer the opportunity to make a big step forward to establish the room-temperature rechargeable FSBs. Acknowledgement. This work was supported by the Research and Development Initiative for Scientific Innovation of New Generation Battery 2 (RISING2), financially supported by New Energy and Industrial Technology Development Organization (NEDO).