Green Energy Storage Research Articles

Both MOFs-derived Fe-Co-Ni ternary hydroxide positive and Fe2O3/reduced graphene oxide negative electrode for asymmetric supercapacitors

To design and construct high-performance asymmetric supercapacitors (ASC), we use the same Fe-based metal-organic framework (MIL-88A) as the precursor for the first time to prepare iron-cobalt-nickel ternary metal hydroxides (Fe-Co-Ni-OH) and Fe2O3 compounded with reduced graphene oxide (Fe2O3/RGO-1). As a positive electrode, Fe-Co-Ni-OH has a specific capacitance of 1065 F g−1 at 1 A g−1 and exhibits excellent rate performance and cycle stability due to its unique spindle-like structure of the surface growth nanosheets and the synergistic effect between the three metals. The introduction of RGO effectively connects the independent spindle-like Fe2O3 and enhances the conductivity and structural stability of the material. So that the Fe2O3/RGO-1 negative electrode has a specific capacitance of 734 F g−1 at 1 A g−1, and its cycle stability is significantly improved compared with the single Fe2O3 (increasing from 64 % to 85 %). The constructed Fe-Co-Ni-OH//Fe2O3/RGO-1 ASC possesses a satisfactory energy density of 43.11 Wh kg−1 at a power density of 800 W kg−1, which is superior to parts constructed with similar material compositions in the same period. This research provides a new perspective for developing high-performance, low-cost, and environmentally friendly green energy storage devices.

Trimetallic Layered Hydroxide Anchored on a Bimetallic NiCo-MOF Derivative as a Self-Supporting Electrode Material for Boosting Supercapacitance

The electrochemical properties of the layered double hydroxides (LDHs) are influenced by both composition and nanostructure to a great extent. In this work, a novel composite electrode material NiCoC/O-NiCoAl LDH was synthesized using a bimetallic NiCo-metal–organic framework (MOF) as the precursor. The composite electrode material NiCoC/O-NiCoAl LDH exhibited a three-dimensional (3D) nanoflower-like structure and multiple surface element state and was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS) measurements. The electrode material exhibited an outstanding specific capacitance of 2400 F g–1 at a current density of 1 A g–1. The fabricated aqueous hybrid supercapacitor NiCoC/O-NiCoAl LDH//AC exhibited an energy density of 80 W h kg–1 at a power density of 750 W kg–1. In addition, the fabricated device exhibited excellent cycling stability and durability. The present work provides a suggestive contribution to the design and synthesis of 3D NiCoC/O-NiCoAl LDH as well as their potential applications in green energy storage.

Construction of a porous carbon skeleton in wood tracheids to enhance charge storage for high-performance supercapacitors

Wood with vertically aligned tracheids has many potential applications in energy storage. Carbonized wood inherits the previous tracheid structure and has good electrical conductivity, which provides favorable conditions for its application in self-supporting electrodes of supercapacitors. However, problems such as low specific surface area, low space utilization, and hydrophobicity limit the development of wood-derived carbon (WC) as an electrode material. Here, to improve the specific surface area and tracheid space utilization of WC, a porous carbon skeleton (PCS) was simply and efficiently constructed in its interior by using glucose and sodium chloride templates, and then potassium hydroxide etching treatment was used to further improve the specific surface area and hydrophilicity of the PCS, resulting in an etched porous carbon skeleton (E-PCS). The prepared E-PCS@WC electrode had an excellent area/volumetric specific capacitance of 7.29 F cm−2/145.8 F cm−3, and the supercapacitor exhibited a high volumetric capacitance and volumetric energy density of 34.99 F cm−3 and 4.86 mWh cm−3 at a power density of 2.5 mW cm−2. The supercapacitor constructed from this electrode exhibited good cycling stability with a retention rate of 98.5% over 20,000 cycles at a current density of 50 mA cm−3. This research will provide new ideas and a scientific basis for the design, construction and application of new green energy storage devices.

Microstructurally assembled transition metal oxides with cellulose nanocrystals for high-performance supercapacitors

Owing to the rapid growth in fossil fuel consumption and the related ecological concerns, alternative routes such as green energy and efficient storage technologies have been developed; many technologies require the fabrication of supercapacitor devices. Cellulose nanocrystals (CNCs) can be used to make composites; their structural, morphological, and mechanical properties result in high-performance sensors, supercapacitors, and electrocatalysts. Cellulose nanocrystal (CNC) materials are promising sustainable and environmentally friendly candidates for the development of green and renewable electronics for energy conversion processes. In this study, hierarchical CoFe2O4@CNC nanocomposite was synthesized to prepare electrodes for supercapacitors, also prepared the pristine CoFe2O4 sample for comparison. The composite materials were characterized with different techniques to determine the structural, morphological, surface, and electrochemical characteristics. Furthermore, the electrochemical characteristics were examined with CV, GCD, and EIS studies to assess the suitability for supercapacitor applications. The synthesized nanocomposite materials exhibit improved electrolyte/electrode surfaces, which promote the diffusion of ions. The CoFe2O4@CNC nanocomposite has 629 F/g capacitance at 0.5 A/g and retains 95.8% capacitance after 5000 cycles. Therefore, the creation of highly active electrochemical sites via the incorporation of CNC improves the capacitive performance of devices.

Ti4O7 regulating both Zn(OH)42– and electrons for improving Zn–Ni batteries

Zn–Ni battery is prospective green energy storage device. However, Zn(OH)42–, the dissolved product of ZnO in the electrolyte, redistributes during the cycle, leading to the shape changing of the anode. This issue severely limits the lifespan of zinc anodes. Despite the success in improving the electrochemical performances of zinc anode via adding Ti4O7 additive, the important mechanism of such modified anode has not been well understood. In addition, the aluminothermic reduction is facile and energy-saving. But the application of Ti4O7 synthesized by this method in Zn–Ni batteries has not been studied. Herein, Ti4O7 synthesized by facile and rapid aluminothermic reduction was applied to alkaline zinc anode. In subsequent electrochemical tests, the discharge capacity and cyclic performance of the zinc-nickel battery was significantly improved by adding as-prepared Ti4O7 particles. At a high discharge current of 2.5 A (34.54 mA cm−2), the anode modified by Ti4O7 delivered higher discharge capacity of 364 mAh g−1, in contrast to the 283 mAh g−1 of pristine anode. Even at ultra-high discharge current of 10 A (138.16 mA cm−2), the battery operated stably for 480 cycles. Besides, the mechanism of Ti4O7 modifying anode was studied in-depth by a variety of characterizations and density functional theory (DFT) calculations. We discovered that Ti4O7 simultaneously regulates the distribution of electrons on the anode and Zn(OH)42– in the electrolyte, contributing to forming uniform zinc anode during cycling.

Interface engineering to optimize polarization and electric breakdown strength of Ba2Bi3.97Pr0.03Ti5O18/BiFeO3 ferroelectric thin-film for high-performance capacitors

Electrostatic capacitors based on dielectrics are ubiquitous components for applications in modern electronics and electric power systems. However, the relatively low energy density of electrostatic capacitors, which is one or two orders of magnitude lower than that of the batteries, has greatly hindered the implementation of its in energy storage devices. Here, we propose a strategy to overcome the tradeoff between high polarizability and breakdown electric field, and attain great enhancement energy storage density in the lead-free (Ba2Bi3.97Pr0.03Ti5O18/BiFeO3)N (BBPT/BFO)N multilayer ferroelectric thin films with different BFO layers through interface engineering. The interface engineering could be utilized to concurrently modify both polarization and local electric field strength caused by the synergistic effect of multiple polar structures and electric field amplifying effect. Accordingly, the discharged energy density of the optimized (BBPT/BFO)1 ferroelectric thin-film capacitors as high as ∼ 79.3 J/cm3 with discharged efficiency exceeding ∼ 75 % are achieved. Combined with its fatigue-free, favorable temperature and frequency stabilities, the multilayer ferroelectric thin films of BBPT/BFO could be a promising dielectric material for practical energy storage applications.

Predicting the Redox Potentials of Phenazine Derivatives Using DFT-Assisted Machine Learning.

This study investigates four machine-learning (ML) models to predict the redox potentials of phenazine derivatives in dimethoxyethane using density functional theory (DFT). A small data set of 151 phenazine derivatives having only one type of functional group per molecule (20 unique groups) was used for the training. Prediction accuracy was improved by a combined strategy of feature selection and hyperparameter optimization, using the external validation set. Models were evaluated on the external test set containing new functional groups and diverse molecular structures. High prediction accuracies of R2 > 0.74 were obtained on the external test set. Despite being trained on the molecules with a single type of functional group, models were able to predict the redox potentials of derivatives containing multiple and different types of functional groups with good accuracies (R2 > 0.7). This type of performance for predicting redox potential from such a small and simple data set of phenazine derivatives has never been reported before. Redox flow batteries (RFBs) are emerging as promising candidates for energy storage systems. However, new green and efficient materials are required for their widespread usage. We believe that the hybrid DFT-ML approach demonstrated in this report would help in accelerating the virtual screening of phenazine derivatives, thus saving computational and experimental costs. Using this approach, we have identified promising phenazine derivatives for green energy storage systems such as RFBs.

A green hydrogen energy storage concept based on parabolic trough collector and proton exchange membrane electrolyzer/fuel cell: Thermodynamic and exergoeconomic analyses with multi-objective optimization

With the continuous penetration of renewable energy plants into energy markets and their surplus power generation during off-peak periods, the need for utility-scale energy storage technologies is globally prioritized. Among the existing large-scale energy storage technologies, hydrogen storage has appeared as a powerful alternative due to its environmental benefits and the ability to store a large amount of energy for several hours to months. The major objective of the proposed research is to introduce a novel configuration of green hydrogen production for power generation during peak demand periods. In this regard, an innovative hybridization of a solar unit based on a parabolic trough collector with a proton-exchange membrane electrolyzer and a fuel cell is introduced and analyzed from the thermodynamic and exergoeconomic perspectives. Moreover, a sensitivity analysis and a multi-objective optimization based on the combination of neural network and grey wolf optimization algorithms are conducted to select the best working fluid of the solar unit and ideal operating conditions according to the minimum cost rate and the maximum exergy efficiency. The results indicate that Dowtherm™ A synthetic oil is the best working fluid, and the proposed system can generate 9, 14.9, and 20.1 MW of power during off-, mid-, and on-peak times, respectively. The results also show that the proposed system operates with an exergy efficiency of 17.6% and a cost rate of 492.4 $/hr under the optimal conditions.

Self-assembled cotton-like copper–molybdenum sulfide and phosphide as a bifunctional electrode for green energy storage and production

As the world's energy needs grow and environmental concerns intensify, there is an increasing need for research into developing new materials that may be used in energy production and storage. Herein, we developed copper-molybdenum (Cu–Mo) sulfide and phosphide-based cotton-like nanoarchitectures via hydrothermal strategy and they were characterized using various analytical techniques. The prepared sulfide and phosphide-based materials showed HER overpotentials of 207 mV and 147 mV, respectively, as well as Tafel slope values of 118 mV/dec and 109 mV/dec at 10 mA/cm2. While OER at the same current density showed 270 mV and 213 mV overpotentials with 82 mV/dec and 48 mV/dec Tafel slope, respectively. In addition, the prepared sulfide and phosphide-based materials showed significant performance towards supercapacitors, displaying specific capacitances of 3.5 and 5.2 F/cm2 at 3 mA/cm2, and retaining their specific capacitances by 86.9 and 69.4%, respectively, after 4,000 cycles with 100% Coulombic efficiency. These materials have the potential to be employed for energy production and storage because of their excellent electrochemical characteristics and bifunctional performance.

Boosting the OER/ORR/HER activity of Ru-doped Ni/Co oxides heterostructure

The development of cheap and efficient OER/ORR/HER electrocatalysts is important to promote green energy conversion and storage technologies. Experimental results show that the synergistic effect of Ru doping and NiO/Co3O4 heterostructure can significantly improve the catalytic activity. The existence of NiO/Co3O4 heterostructure, the appropriate proportion of Ru (only 2%) and the proper electronic energy state tuning are determined by electronic detection and elemental analysis, which enhanced the activation energy, electrical conductivity and electrochemical active surface area of the catalyst. Thus, the Ru-doped NiO/Co3O4 heterostructure exhibits superior OER/ORR/HER performance, reaching 100 mA cm−2 in alkaline electrolytes at only 138 mV (HER) and 269 mV (OER) overpotential, and a high half-wave potential of 0.88 V (ORR). The water-splitting device assembled by the catalyst can operate stably for a long time (>40 h), better than Pt/C and RuO2 at high current densities.

Achieving in-situ hybridization of NaTi2(PO4)3 and N-doped carbon through a one-pot solid state reaction for high performance sodium-ion batteries

The development of green, sustainable and low-cost energy storage materials through simple and environmental friendly routes is of great significance for futural large-scale energy storage systems. Due to its unique sodium super ionic conductor (NASICON) structure, polyanion-type NaTi2(PO4)3 (NTP) is regarded as one of the promising potential cathode materials for sodium-ion batteries (SIBs). However, its practical application has been impeded by its intrinsic poor conductivity for unmodified NTP. To resolve this issue, this work hybridizes the NTP with a N-doped carbon matrix (NC) through a facile one-pot solid state reaction, taking an organophosphonic acid (ethylenediamine tetramethylene phosphonic acid, EDTMPA) as source material providing carbon, nitrogen and phosphorous element at the same time. The as-prepared NTP@NC composite not only possesses improved electrical conductivity, but also mitigates particle agglomeration during prolonged charge-discharge cycles. As a result, the NTP@NC composite exhibits an outstanding sodium storage behavior, in terms of a high specific charge capacity (105.6 ​mA ​h ​g−1 at 0.2 ​C with 87.3% initial coulombic efficiency), an excellent cycle performance (101.2 ​mA ​h ​g−1 charge capacity after 100 cycles at 0.2 ​C with a charge capacity retention of 95.8%) and outstanding rate capabilities (103.6 ​mA ​h ​g−1 charge capacity at 1 ​C and 71.5 ​mA ​h ​g−1 at 5 ​C, respectively).

Facile Synthesis of Sustainable Biomass-Derived Porous Biochars as Promising Electrode Materials for High-Performance Supercapacitor Applications.

Preparing sustainable and highly efficient biochars as electrodes remains a challenge for building green energy storage devices. In this study, efficient carbon electrodes for supercapacitors were prepared via a facile and sustainable single-step pyrolysis method using spruce bark as a biomass precursor. Herein, biochars activated by KOH and ZnCl2 are explored as templates to be applied to prepare electrodes for supercapacitors. The physical and chemical properties of biochars for application as supercapacitors electrodes were strongly affected by factors such as the nature of the activators and the meso/microporosity, which is a critical condition that affects the internal resistance and diffusive conditions for the charge accumulation process in a real supercapacitor. Results confirmed a lower internal resistance and higher phase angle for devices prepared with ZnCl2 in association with a higher mesoporosity degree and distribution of Zn residues into the matrix. The ZnCl2-activated biochar electrodes’ areal capacitance reached values of 342 mF cm−2 due to the interaction of electrical double-layer capacitance/pseudocapacitance mechanisms in a matrix that favors hydrophilic interactions and the permeation of electrolytes into the pores. The results obtained in this work strongly suggest that the spruce bark can be considered a high-efficiency precursor for biobased electrode preparation to be employed in SCs.

Green energy: identifying development trends in society using Twitter data mining to make strategic decisions

This study analyzes Twitter’s contribution to green energy. More than 200,000 global tweets sent during 2020 containing the terms “green energy” OR “greenenergy” were analyzed. The tweets were captured by web scraping and processed using algorithms and techniques for the analysis of massive datasets from social networks. In particular, relationships between users (through mentions) were determined according to the Louvain multilevel algorithm to identify communities and analyze global (density and centralization) and node-level (centrality) metrics. Subsequently, the content of the conversation was subject to semantic analysis (co-occurrence of the most relevant words), hashtag analysis (frequency analysis), and sentiment analysis (using the VADER model). The results reveal nine main communities and their leaders, as well as three main topics of conversation and the emotional state of the digital discussion. The main communities revolve around politics, socioeconomic issues, and environmental activism, while the conversations, which have developed mostly in positive terms, focus on green energy sources and storage, being aligned with the main communities identified, i.e., on political, socioeconomic, and climate change issues. Although most of the conversations have been about socioeconomic issues, the presence of leading company accounts was minor. The main aim of this work is to take the first steps toward an innovative competitive intelligence methodology to study and determine trends within different scientific fields or technologies in society that will enable strategic decisions to be made.

Enhanced energy storage performance of 0.88(0.65Bi0.5Na0.5TiO3-0.35SrTiO3)-0.12Bi(Mg0.5Hf0.5)O3 lead-free relaxor ceramic by composition design strategy

Dielectric ceramic capacitors with high energy density are one of the great bright energy storage devices. Here, the Bi0.5Na0.5TiO3, 0.75Bi0.5Na0.5TiO3-0.25SrTiO3, 0.65Bi0.5Na0.5TiO3-0.35SrTiO3 and 0.88(0.65Bi0.5Na0.5TiO3-0.35SrTiO3)-0.12Bi(Mg0.5Hf0.5)O3, (abbreviated as BNT, BNT-25ST, BNT-35ST and BNST-BMH, respectively) ceramics were produced by solid state sintering method. The influence of solid solution of SrTiO3 and Bi(Mg0.5Hf0.5)O3 doping in Bi0.5Na0.5TiO3 on crystal structure, microstructure, electrical and energy storage performance were evaluated systematically. By optimizing ceramics composition, high breakdown field and slim hysteresis loops were simultaneously realized due to enhanced band gap, refined grain size and nano-domains formed, which can be verified by the transmission electron microscope (TEM), piezoelectric force microscope (PFM) and ultraviolet–visible spectrum. Therefore, an ultrahigh recoverable energy density of 5.59 J/cm3 with brilliant efficiency of 85.3% is realized in BNST-BMH ceramic. Besides, the BNST-BMH also exhibits prominent temperature stability at 20–140 °C, superior fatigue resistance beyond 105 cycles and outstanding frequency stability at 1–200 Hz. Our work offers a novel way for designing dielectric capacitors and also proves that BNST-BMH is indeed a great hopeful dielectric energy storage material in pulse power electronics.

Flexible and Alternately Layered High‐Loading Film Electrode based on 3D Carbon Nanocoils and PEDOT:PSS for High‐Energy‐Density Supercapacitor

AbstractThe development of flexible carbon‐based film electrodes with high loading and sufficient electron/ion transport channels is of great significance but still challenging. Herein, a flexible high‐loading (over 15 mg cm–2) film with 3D hierarchical pores is prepared by an alternate deposition of carbon nanocoils (CNCs) and poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS). The unique alternate architecture of CNC/PEDOT:PSS bilayers possesses porous structure constructed by interconnected CNCs, which serves as transfer channels and storage chambers of ions. Meanwhile, the PEDOT:PSS layers anchoring CNCs function as not only the cement to ensure the stability of the film structure but also the current collectors to improve electron transfer kinetics between interlayers. The film electrode shows excellent flexibility and electrochemical properties. It delivers a high areal capacitance of 1402.5 mF cm–2 at 0.25 mA cm–2 and a superior stability even at an extremely high current density of 50 mA cm–2 after 10 000 cycles. The corresponding solid‐state supercapacitor has great energy storage ability and steady capacitance response under various deformation. The device achieves a superb energy density of 211 μW h cm–2 with a wide potential window of 2 V. This strategy paves a road for the controllable fabrication of high‐performance flexible electrodes and supercapacitors.

Effects of intake high-pressure compressed air on thermal-work conversion in a stationary diesel engine

ABSTRACT Compressed air energy storage is one of the green energy storage and conversion systems. In this work, the compressed air was directly supplied to a stationary diesel engine to investigate the effects of compressed air characteristics on the process of thermal-work conversation in diesel engines. Then, the thermal efficiency of supplying compressed air to a diesel engine is compared against a simple hybrid system that consists of a compressed air engine and a baseline diesel engine. The results indicate that the compressed air affects the thermal work conversion of diesel engine. The gross indicated mean effective pressure is being used to quantify the in-cylinder pressure work that transferred to the piston motion only for the combustion and expansion strokes, which increases as the pressure of compressed air increases and decreases as the temperature of the compressed air increases. The gross indicated thermal efficiency that represents the ability of thermal-work conversion is maximum at intake pressure of 300 kPa and intake temperature of 303 K with a value of 44.3%, which is 19.7% higher than that of the baseline diesel engine with 100 kPa intake pressure and 303 K intake temperature. The diesel engine using compressed air shows 6.64% higher overall efficiency than the simple hybrid system. The soot emissions increase with increasing intake pressure, and decrease with increasing intake temperature. As the intake temperature increases, NOx emissions increase. As the intake pressure increases, NOx emissions first decrease and then increase.

Target design towards HER inhibition for an electrolytic Mn//MnO2 aqueous battery with high discharge voltage

As popular green energy storage devices, Zn//MnO2 batteries have attracted widespread attention. However, issues caused by Zn based anodes and rocking-chair Zn2+ mechanism on cathodes have hindered their fast development. Herein, a new electrolytic Mn//MnO2 system without initial active materials is developed, where the main challenge is the realization of Mn plating that is highly involved with the inhibition of hydrogen evolution reaction (HER) during charging. To overcome this challenge, rational design is conducted (mainly including surface design of the current collectors, and the use of “water-in-salt” electrolytes): polyaniline (PANI) loaded on heat treated carbon cloth (CC-400/PANI) and CC-400 with microspores is constructed as current collector for anode and cathode, respectively; high concentrated aqueous of 20 m LiCl + 1 m MnCl2 is used as electrolyte to reduce the activity of water and hence extend its operating window. In this system, HER is largely inhibited, and reversible Mn/Mn2+ reaction is realized on the anode; Mn2+/MnO2 concerned reaction is realized on the cathode; a high discharge voltage of ∼2.3 V with a cycling life of 500 cycles is accomplished for a full cell. Coulombic efficiency (CE) is enhanced to 80–90% along cycling. Through carefully analysis, it is found that irreversible reaction of Mn2+/MnO2 on the cathode is the main cause for the unsatisfied CE. The rechargeable electrolytic Mn//MnO2 system proposed here is a promising candidate as green and efficient aqueous cell for safe and large-scale charge storage.

Biomass Hyaluronic Acid to Construct High‐Loading Electrode with Fast Na+ Transport Structure for Na3V2(PO4)3 Sodium‐Ion Batteries

AbstractSodium‐ion batteries (SIBs) are considered a promising candidate in green energy storage due to their considerable abundance. The low mass loading (less than 2.0 mg cm−2) of SIBs‐based cathodes cannot meet the energy density on the practical device level, which is mainly restricted by sluggish Na+ transport. To the end, a facile and compatible strategy was demonstrated by utilizing hyaluronic acid (HA) binder to achieve fast ion transport and targeted energy density for Na3V2(PO4)3 (NVP) cathodes. As a novel functional aqueous binder, HA allowed cathodic materials to organize the unique conductive network. The network‐like electrode structure could buffer volume changes during sodiation/desodiation process and provide bi‐continuous charge transport channels for both Na+ and electrons at the interface. HA promoted the formation of the stable solid permeable interface films, protecting the electrochemical stability of the cathode and ensuring its good cycle performance. These functions of HA binder enabled that NVP delivered a reversible discharge capacity of 107.3 mAh g−1 at 0.5 C (1 C=117 mA g−1), which showed no sacrifice of electrochemical performances with mass loading increasing from 1.1 to 4.4 mg cm−2. Even at a high rate of 20 C, NVP‐HA (loading 4.0 mg cm−2) could reserve a good capacity of 76.8 mAh g−1 with the retention of 99.3 % after 2000 cycles. This study provides a novel strategy to achieve high energy density for SIBs in large‐scale energy storage.

A Facile Design of Solution-Phase Based VS2 Multifunctional Electrode for Green Energy Harvesting and Storage.

This work reports the fabrication of vanadium sulfide (VS2) microflower via one-step solvo-/hydro-thermal process. The impact of ethylene glycol on the VS2 morphology and crystal structure as well as the ensuing influences on electrocatalytic hydrogen evolution reaction (HER) and supercapacitor performance are explored and compared with those of the VS2 obtained from the standard pure-aqueous and pure-ethylene glycol solvents. The optimized VS2 obtained from the ethylene glycol and water mixed solvents exhibits a highly ordered unique assembly of petals resulting a highly open microflower structure. The electrode based on the optimized VS2 and exhibits a promising HER electrocatalysis in 0.5 M H2SO4 and 1 M KOH electrolytes, attaining a low overpotential of 161 and 197 mV, respectively, at 10 mA.cm−2 with a small Tafel slope 83 and 139 mVdec−1. In addition, the optimized VS2 based electrode exhibits an excellent electrochemical durability over 13 h. Furthermore, the superior VS2 electrode based symmetric supercapacitor delivers a specific capacitance of 139 Fg−1 at a discharging current density of 0.7 Ag−1 and exhibits an enhanced energy density of 15.63 Whkg−1 at a power density 0.304 kWkg−1. Notably, the device exhibits the capacity retention of 86.8% after 7000 charge/discharge cycles, demonstrating a high stability of the VS2 electrode.

Wood-plastic materials with organic–inorganic hybrid phase change thermal storage as novel green energy storage composites for building energy conservation

Wood-plastic materials with organic–inorganic hybrid phase change thermal storage as novel green energy storage composites for building energy conservation