Energy Storage Applications Research Articles

2D Transition Metal Chalcogenides (TMDs) for Electrocatalytic Hydrogen Evolution Reaction: A Review.

Since the MoS2 synthesis, the family of two-dimensional transition metal chalcogenides (TMDs) have been intensively explored theoretically and experimentally. TMDs endowed with adjustable electronic, physical and chemical properties lead to increasing interest in the application of energy storage, molecule detection and catalysis. In the mini review, we present a forward-looking summary of 2D TMDs in hydrogen evolution electrocatalysis, including synthesis methods, hydrogen evolution performance, and optimization strategies. This review will deepen the fundamental understanding of the physical-chemical properties of TMDs with different phases and contribute unveil the universal principle among electronic configuration, atomic arrangement, physical and chemical property for the material design.

Structural, optical, electrical, and dielectric properties of HPMC/PVP blend reinforced with I2O5 for optoelectronics and energy storage applications

Structural, optical, electrical, and dielectric properties of HPMC/PVP blend reinforced with I2O5 for optoelectronics and energy storage applications

Characterization of green-synthesized carbon quantum dots from spent coffee grounds for EDLC electrode applications

This study investigates the green synthesis of carbon quantum dots (CQDs) from spent coffee grounds using a hydrothermal method, offering an eco-friendly, cost-effective, and straightforward approach to nanomaterial production. The synthesized CQDs, with particle sizes ranging from 1.6 to 4.4 nm, exhibited notable fluorescence, achieving quantum yields of 37.0 %, 54.3 %, and 63.3 % depending on the coffee source. Characterization technique, including XRD, FTIR, SEM, TEM, and BET, confirmed their structural suitability of these CQDs for energy storage applications. Their electrochemical performance was evaluated through cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), and electrochemical impedance spectroscopy (EIS). Among the CQDs tested, those derived from spent Liberica coffee ground (medium roasted) demonstrated superior performance, with a discharging specific capacitance of 97.5 F/g, an energy density of 4.3 Wh/kg, and a power density of 130.6 W/kg at a current density of 0.5 A/g. Additionally, they exhibited acceptable internal resistance (Ra = 0.01 kΩ and Rab = 16.9 kΩ), indicating favourable charge transfer characteristics. These results underscore the enhanced energy storage potential of CQDs derived from spent coffee grounds. The findings not only highlight the excellent electrochemical performance but also support the viability of biomass waste as a valuable resource for advanced energy storage applications, promoting sustainable, eco-friendly technologies.

Solvation structures in weakly solvating solvents lead to hybrid vehicular/structural ion transport

Despite the reported benefits of weakly solvating electrolytes (WSEs), investigations on the solvation structures and ion transport mechanisms present in WSEs are limited. This is particularly the case for electrolytes containing the weakly solvating 1,2-diethoxyethane (DEE), which has shown great promise recently. It is for this purpose, we employ molecular dynamics simulations and quantum mechanical calculations to investigate the solvation structure and Li+ transport for lithium bis(fluorosulfonyl)imide (LiFSI) in DEE. From the results reported herein, it was found that at lower concentrations, solvent separated ion pairs are particularly stable, primarily due to the presence of FSI– in the second solvation shell of Li+. As the salt concentration increases, cation–anion complexes appear and form large aggregates. The presence of these large aggregates promotes a hybrid/structural diffusion mechanism at high concentrations, where Li+ ions readily exchange ligands with FSI– anions but remains coordinated with DEE molecules. Hence, the results reported herein investigate how the solvation structure influences transport properties in weakly solvating solvents and provides insights that can be used to optimize electrolytes for energy storage applications.

Facile synthesis of GexSiO(1-x) alloys as a superior anode enables high-energy lithium-ion batteries

The large-scale development of low-cost silicon monoxide (SiO) anode is limited due to its low initial Coulombic efficiency (ICE) and poor cycle stability. Herein, the GexSiO(1-x) (0<x<1) composite anode has been facile synthesized by introducing germanium (Ge) atoms disrupted the structure of SiO matrix, which exhibits superior lithium storage performance. In particular, the optimized Ge0.5SiO0.5 electrode with nanoscale dispersion shows a high ICE of 80.2 % and a reversible capacity of 673.9 mAh g−1 after 100 cycles. To evaluate the effect of the Ge addition on the electrochemical properties, the lithium storage behaviors and structural evolution of the GexSiO(1-x) electrodes are investigated systematically. The in-situ electrochemical dilatometry reveals that the Ge0.5SiO0.5 electrode displays a better reversible thickness variation during cycling process. Density functional theory (DFT) calculation demonstrates that the SiGe domain can accommodate the volume expansion of Si and Ge domains. Moreover, the relationships between the electrochemical performance and morphology evolution demonstrate that the disordered structure and nanoscale distribution of Ge0.5SiO0.5 electrodes are the main reasons for improving ICE and cycle stability. This work provides a commercially available synthetic route for the design of advanced anode materials for large-scale energy storage applications.

Flexible poly (ethylene-co-vinyl acetate)/copper oxide nanocomposites: A promising avenue for energy storage applications

The use of metal oxide nanoparticles in polymeric materials to improve optical properties, dielectric constant, mechanical strength, and electrical conductivity has generated significant interest in fabricating flexible optoelectronic and energy storage devices. Herein, copper oxide (CuO) nanoparticle-reinforced poly (ethylene-co-vinyl acetate) (EVA) nanocomposites were prepared using a solvent-free two roll mill mixing method. Fourier transform infrared (FTIR) analysis reveals the distinct absorption peaks of CuO in the EVA matrix. The addition of CuO nanoparticles improved the crystallinity of EVA, as confirmed by X-ray diffraction (XRD). The addition of CuO to EVA led to an increase in the refractive index and a decrease in bandgap energy, as well as a broadening and intensification of UV–visible absorption, indicating strong interactions between CuO nanoparticles and the EVA matrix. Field emission scanning electron microscopy (FE-SEM) and high-resolution transmission electron microscopy (HR-TEM) revealed a homogeneous dispersion of CuO nanoparticles throughout the EVA matrix. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) demonstrated that the incorporation of CuO nanoparticles into EVA significantly enhanced its thermal properties. The electrical characteristics studies showed that the AC conductivity and dielectric constant of EVA increased significantly with increasing temperatures and CuO nanoparticle loading levels. EVA containing 5 wt% CuO exhibited the highest conductivity and the lowest activation energy. CuO nanoparticle reinforcement significantly enhanced the tensile, tear, and impact strength of EVA while reducing elongation at break up to a particular concentration. The nanocomposites containing 5 wt% CuO exhibited the highest tensile, tear resistance, and impact strengths, outperforming virgin EVA by 85 %, 103.6 %, and 83.16 %, respectively. These findings suggest that EVA/CuO nanocomposites are promising candidates for flexible dielectric materials.

Ultrahigh Energy Storage of Twisted Structures in Supramolecular Polymers.

Polymer dielectrics possess outstanding advantages for high-power energy storage applications such as high breakdown strength (Eb) and efficiency (η), while both of them decrease rapidly at elevated temperatures. Although several strategies have been evaluated to enhance Eb and heat resistance, the discharged energy density (Ud) is still limited by the planar conjugated structure. In this study, a novel approach to manipulate polymer morphology is introduced, thereby influencing dielectric properties. A range of polyurea (PU)-based polymers are predicted from different structural unit combinations by machine learning and synthesized two representative polymers with high dielectric constants (K) and thermal stability. These polymers are combined with PI to form a twisted polymer via hydrogen bonding interactions (HNP). Both experimental results and computational simulations demonstrate the twisted structure disrupts the conjugated structure to widen the bandgap and increase dipole moment through the twisting of polar groups, leading to simultaneous improvements in both K and Eb. Consequently, HNP-20% achieves an ultrahigh Ud of 6.42 Jcm-3 with an efficiency exceeding 90% at 200 °C. This work opens a new avenue to scalable high Ud all-polymer dielectric for high-temperature applications.

Modeling and characterization of the mechanical properties of nanofiber yarn

This study investigates the mechanical properties and unique structural features of nanofiber yarns produced via electrospinning. Through experimental, analytical, and numerical methods, the tensile behavior of the yarns was evaluated. Nanofiber yarns, composed of submicron-diameter fibers, exhibit a significantly larger surface area and stronger fiber interactions compared to conventional yarns. These structural characteristics result in a marked improvement in mechanical properties, with the nanofiber yarns showing a 25% increase in stiffness and a 15% enhancement in damping capacity. A three-element viscoelastic model was applied to accurately describe the nonlinear tensile response of the yarns, with a high correlation to experimental data (R2 > 0.999). Furthermore, nanofiber yarns demonstrated superior thermo-mechanical stability, with a tan δ peak observed at 108 °C, compared to 100 °C for conventional yarns. These findings suggest that nanofiber yarns are promising candidates for applications in tissue engineering, filtration, energy storage, and other high-performance fields. The research provides a solid foundation for further optimization of nanofiber yarns to fully exploit their mechanical potential.

Helmholtz Plane Regulation Empowers PF6− Permselectivity Towards High Coulombic Efficiency Dual Ion Battery of 5.5 V

AbstractHigh‐voltage dual ion battery (DIB) is promising for stationary energy storage applications owing to its cost‐effectiveness, which has been a hot topic of research in rechargeable battery fields. However, it still suffers from rapid battery failure caused by the severe solvent co‐intercalation and electrolyte oxidation. To address these bottlenecks, herein a functional electrolyte additive hexafluoroglutaric anhydride (HFGA) is presented based on a Helmholtz plane regulation strategy. It is demonstrated that the HFGA can precisely enter into the Helmholtz plane and positively regulate anion solvation behaviors near the graphite electrode surface owing to its considerable H−F affinity with ethyl methyl carbonate (EMC), thus alleviating EMC‐related co‐intercalation and oxidation decomposition during DIB charging. Meanwhile, HFGA can copolymerize with the presence of PF5 at the Helmholtz plane to participate in forming a CF2‐rich CEI layer with excellent PF6− permselectivity, conducive to achieving PF6− de‐solvation and simultaneously suppressing electrolyte oxidation decomposition. By virtue of such beneficial effects, the graphite cathode enables a 5.5 V DIB with a prominent capacity retention of 92 % and a high average Coulombic efficiency exceeding 99 % within 2000 cycles at 5 C, demonstrating significantly enhanced electrochemical reversibility. The Helmholtz plane regulation strategy marks a milestone in advancing DIB technologies.

An Evaluation of the Levelised Cost of Storage of Buoyancy Energy Storage Technology at Smaller Scales

Buoyancy Energy Storage Technology (BEST) offers a promising solution to the intermittency of renewable energy sources like wind and solar. This paper aims to evaluate the feasibility of using BEST for small- scale energy storage applications. The methodology involves calculating the levelized cost of storage (LCOS) and energy capacity of two BEST variants: Fabric BEST and Reeling BEST. Results indicate that Fabric BEST can store 96 kWh per cycle with an LCOS of $356.73/MWh, while Reeling BEST stores less energy at a significantly higher cost of $683/MWh.

Saponification residue–sodium nitrate morphologically stable phase-change materials for medium- and high- temperature thermal energy storage

Saponification residue (SR) is a by-product of the chlor-alkali process used to produce propylene oxide. Owing to its high porosity and large specific area, SR is suitable as a carrier in the preparation of composite phase-change materials (CPCMs). This approach not only addresses the leakage issues associated with phase-change energy storage materials but also utilises solid waste. Herein, a morphologically stable CPCM was prepared using industrial SR solid waste and a phase-change material (sodium nitrate) via a hybrid sintering method. Phase analyses by X-ray diffractometer showed good chemical compatibility between sodium nitrate and SR. Further, scanning electron microscopy showed that SR has a porous structure, and sodium nitrate can be stably adsorbed on the pores and surface of SR. The maximum compressive strength of SR-CPCM was 43.37 MPa. Moreover, the highest loading capacity of SR for sodium nitrate was 50 wt%, resulting in no leakage and remarkable morphological stability. Differential scanning calorimetry indicated that SR-CPCM exhibited adequate thermal stability and that the latent heat increased with rising nitrate content, reaching a maximum value of 99.24 J/(g·°C). Importantly, after 100 thermal cycles, SR-CPCM demonstrated good stability in terms of chemical compatibility and latent heat. These results demonstrate the potential of SR as a carrier material for energy storage applications.

Sol-gel synthesis, characterizations of efficient Y3+ doped ZnO nanoparticles for photocatalytic dye degradation and energy storage applications

Sol-gel synthesis, characterizations of efficient Y3+ doped ZnO nanoparticles for photocatalytic dye degradation and energy storage applications

Helmholtz Plane Regulation Empowers PF6 - Permselectivity Towards High Coulombic Efficiency Dual Ion Battery of 5.5 V.

High-voltage dual ion battery (DIB) is promising for stationary energy storage applications owing to its cost-effectiveness, which has been a hot topic of research in rechargeable battery fields. However, it still suffers from rapid battery failure caused by the severe solvent co-intercalation and electrolyte oxidation. To address these bottlenecks, herein a functional electrolyte additive hexafluoroglutaric anhydride (HFGA) is presented based on a Helmholtz plane regulation strategy. It is demonstrated that the HFGA can precisely enter into the Helmholtz plane and positively regulate anion solvation behaviors near the graphite electrode surface owing to its considerable H-F affinity with ethyl methyl carbonate (EMC), thus alleviating EMC-related co-intercalation and oxidation decomposition during DIB charging. Meanwhile, HFGA can copolymerize with the presence of PF5 at the Helmholtz plane to participate in forming a CF2-rich CEI layer with excellent PF6 - permselectivity, conducive to achieving PF6 - de-solvation and simultaneously suppressing electrolyte oxidation decomposition. By virtue of such beneficial effects, the graphite cathode enables a 5.5 V DIB with a prominent capacity retention of 92 % and a high average Coulombic efficiency exceeding 99 % within 2000 cycles at 5 C, demonstrating significantly enhanced electrochemical reversibility. The Helmholtz plane regulation strategy marks a milestone in advancing DIB technologies.

High-Energy Sodium Ion Batteries Enabled by Switching Sodiophobic Graphite into Sodiophilic and High-Capacity Anodes.

Owing to the crustal abundance of sodium element, sodium ion batteries (SIBs) are considered a promising complementary to lithium-ion battery for stationary energy storage applications. The cointercalation chemistry enables the use of cost-effective graphite as anodes, whereas the low capacity (<130 mAh g-1) and high redox potential (>0.6 V vs. Na/Na+) of graphite significantly limit the energy density of SIBs. Herein, we induce the high-capacity Na metal into sodiophilic ternary graphite intercalation compounds (t-GICs) via co-intercalation and deposition reactions, thereby achieving Na/t-GIC anodes with high capacities and low working voltage (0.18 V). The new anodes exhibit high coulombic efficiencies of above 99.7 % over 550 cycles and a high-rate capacity of 588.4 mAh g-1 at 6 C (10 min per charge). When it is paired with Na3V2(PO4)2F3 (NVPF) cathodes, the SIBs demonstrate a high energy density of 259 Wh kg-1 both electrodes surpassing that of commercial LiFePO4//graphite batteries. The outstanding anode performance is attributed to the tailored sodiophilicity of graphite through manipulating the ether solvents and the in situ generated space among t-GIC flakes to stably accommodate Na metal. Our findings for stable Na plating/striping on sodiophilic graphite materials provide an effective approach for developing advanced SIBs.

Cascaded utilization of magnetite nanoparticles@onion-like carbons from wastewater purification to supercapacitive energy storage.

Developing high-performance carbon-based materials for environmental and energy-related applications produces solid waste with secondary pollution to the environment at the end of their service lives. It is still challenging to utilize these functional materials in a sustainable manner in different fields. In this study, we demonstrate a cascaded utilization of an Fe3O4@onion-like carbon (Fe3O4@OLC) structure from wastewater adsorbents to a supercapacitor electrode. The structure was formed by carbonizing Fe3O4@oleic acid monodisperse nanoparticles into interconnected Fe3O4@OLCs and subsequent insufficient acid etching. The hollow OLCs in the outside region of the hybrid structure provide high surface area and the encapsulated Fe3O4 nanoparticles in the inside region offer high ferromagnetism. The three-dimensionally interconnected graphitic layers are advantageous for efficient separation and high conductivity. As a result, the maximum saturation adsorption capacity of insufficiently etched interconnected Fe3O4@OLCs can reach up to 90.2 mg g-1 and they can be efficiently separated under a magnetic field. Furthermore, the hybrid structure is thermally transformed into N-doped HOLCs, which are demonstrated to be a high-performance supercapacitor electrode with high specific capacitance and high electrochemical stability. The cascaded utilization of the hybrid structure in this study is meaningful for eco-friendly development of functional materials for environmental and energy storage applications.

A High-Voltage n-type Organic Cathode Materials Enabled by Tetraalkylammonium Complexing Agents for Aqueous Zinc-Ion Batteries.

Tetrabutylammonium (TBA) salt of hexacyano-substituted cyclopropane dianion (Cp(CN)6 2 -) is prepared through a facile two-step synthetic protocol from commercially available materials and fully characterized as a high-voltage n-type organic cathode in rechargeable aqueous zinc-ion batteries (AZIBs). The addition of tetrabutylammonium triflate (TBAOTf)to the electrolyte mitigates dissolution issues, leading to enhanced cycling stability. Remarkably, the Cp(CN)6 2 - cathode demonstrates a high discharge voltage of 1.43V in AZIBs and retains 85% of its capacity after 1000 cycles at a high loading of 10mg cm- 2 and a cycling rate of 10C. These results, combined with spectroscopic analyses, elucidate a reversible two-electron redox process of Cp(CN)6 2 - facilitated by the insertion/de-insertion of TBA cation. These findings underscore the potential of Cp(CN)6 2 - as a conversion-based n-type cathode in energy storage applications.

Green Synthesis and Enhanced Photocatalytic Performance of rGO/ZnO/Fe3O4 Nanocomposites: A Sustainable Approach to Environmental Remediation.

The fast industrialization and mounting pollution have necessitated the need for advanced materials in order to degrade pollutants efficiently. Metal oxide-based and graphene-derivative photocatalytic nanocomposites are excellent for harnessing light energy in environmental remediation. Among them, ZnO-based nanocomposites have drawn considerable attention because of their high photocatalytic activity and stability. However, improving the performance of these nanocomposites is still necessary for their wide applications. This study explores the green synthesis, detailed characterization, and enhanced photocatalytic efficiency of reduced graphene oxide rGO/ZnO/Fe3O4 nanocomposites. The nanocomposites were synthesized via a hydrothermal method, utilizing milk thistle extract as a natural reducing agent, representing a novel and sustainable approach to fabricating magnetic rGO/Fe3O4 nanocomposites. These composites were further integrated with zinc oxide to produce a multifunctional material, exhibiting high surface area, superior electrical and thermal conductivity, and robust mechanical strength. The photocatalytic performance was significantly enhanced due to the synergistic interaction between graphene and metal oxide nanoparticles, leading to efficient degradation of environmental pollutants. Electrochemical analysis via cyclic voltammetry revealed distinctive redox peaks, demonstrating efficient electron transfer processes essential for applications in energy conversion and storage. This green synthesis not only provides a sustainable pathway for the development of advanced nanocomposites but also underscores their potential in a wide range of applications, including environmental remediation, sensing, energy storage, and optoelectronics.

Unlocking self-discharge: Unveiling the mysteries of electrode-free Zn-MnO2 batteries with advanced in situ techniques in mild acid aqueous electrolytes

We introduce a novel approach to Zinc-MnO2 battery architecture utilizing a 3D network of carbon nanofibers as both current collector and electrode material, promising enhanced performance and longevity for large-scale energy storage. Employing mild aqueous electrolytes, we address the challenge of managing self-discharge, crucial for short-term energy storage. Advanced coupled characterization techniques, including in-situ EQCM (Electrochemical Quartz Crystal Microbalance) and high-resolution optical microscopy, elucidate self-discharge mechanisms across over multiple length scales. Findings reveal that the self-discharge is mainly at the zinc electrode due to concomitant dissolution of Zinc (corrosion) and HER (Hydrogen Evolution Reaction) phenomena. Interestingly, the corrosion current was estimated irrespective of charging protocol and remains consistent, indicating the independence of zinc corrosion kinetics from the length scale. Finally, the morphology of the zinc layer appears to be critical, suggesting that self-discharge is primarily a chemical process. This innovative design strategy offers the potential for high-performance Zinc-MnO2 batteries with extended cycle life to meet the requirements of large-scale energy storage applications.

Research on self-supporting flexible cathode materials with high LFP loading based on PAN in situ inorganic reaction

High loading flexible electrode material is a key component of flexible batteries. This article prepares a flexible electrode by using electrospinning technology that achieves high conductivity and self-supporting without adhesive and current collector. This structural advantage is attributed to the high compatibility and fibrosis of PAN (polyacrylonitrile) and LFP/CNF, which is transformed in situ by precursor conversion method into a flexible self-supporting composite electrode with continuous carbon fiber/CNF as the conductive phase and LFP(LiFePO4) as the lithium storage phase. These flexible materials achieving a specific capacity of 110.5 mAh/g at 0.1C, 92 mAh/g at 0.5C, and 58 mAh/g at 3C, further demonstrated reversible charge and discharge cycles after mechanical bending. These findings highlight the potential of LFP/CNF electrodes for flexible and high-performance energy storage applications.

High‐Energy Sodium Ion Batteries Enabled by Switching Sodiophobic Graphite into Sodiophilic and High‐Capacity Anodes

AbstractOwing to the crustal abundance of sodium element, sodium ion batteries (SIBs) are considered a promising complementary to lithium‐ion battery for stationary energy storage applications. The cointercalation chemistry enables the use of cost‐effective graphite as anodes, whereas the low capacity (&lt;130 mAh g−1) and high redox potential (&gt;0.6 V vs. Na/Na+) of graphite significantly limit the energy density of SIBs. Herein, we induce the high‐capacity Na metal into sodiophilic ternary graphite intercalation compounds (t‐GICs) via co‐intercalation and deposition reactions, thereby achieving Na/t‐GIC anodes with high capacities and low working voltage (0.18 V). The new anodes exhibit high coulombic efficiencies of above 99.7 % over 550 cycles and a high‐rate capacity of 588.4 mAh g−1 at 6 C (10 min per charge). When it is paired with Na3V2(PO4)2F3 (NVPF) cathodes, the SIBs demonstrate a high energy density of 259 Wh kg−1both electrodes surpassing that of commercial LiFePO4//graphite batteries. The outstanding anode performance is attributed to the tailored sodiophilicity of graphite through manipulating the ether solvents and the in situ generated space among t‐GIC flakes to stably accommodate Na metal. Our findings for stable Na plating/striping on sodiophilic graphite materials provide an effective approach for developing advanced SIBs.