Advanced Energy Storage Technologies Research Articles

Advancing Flow Batteries: High Energy Density and Ultra‐Fast Charging via Room‐Temperature Liquid Metal

AbstractGlobal climate change necessitates urgent carbon neutrality. Energy storage is crucial in this effort, but adoption is hindered by current battery technologies due to low energy density, slow charging, and safety issues. A novel liquid metal flow battery using a gallium, indium, and zinc alloy (Ga80In10Zn10, wt.%) is introduced in an alkaline electrolyte with an air electrode. This system offers ultrafast charging comparable to gasoline refueling (<5 min) as demonstrated in the repeated long‐term discharging (123 h) process of 317 mAh capacity at the current density of 10 mA cm−2 with an average voltage of 1.1 V. A high practical capacity density of 635.1 mAh g−1 is achieved in this brand‐new battery with a potential theoretical value of 1004.4 mAh g−1. Microscopic and numerical simulations reveal significant hydrogen evolution reaction and dendrite suppression compared to Zn and pure Ga electrodes. The potassium iodide (KI)‐modified Ga80In10Zn10‐air battery exhibits a reduced charging voltage of 1.77 V and high energy efficiency of 57% at 10 mA cm−2 over 800 cycles, outperforming conventional Pt/C and Ir/C‐based systems with 22% improvement. This innovative battery addresses the limitations of traditional lithium‐ion batteries, flow batteries, and Zn‐air batteries, contributing advanced energy storage technologies to global carbon neutrality.

Manganese-Coordinated Cellulose Based-Separator for Efficient and Reliable Zn-Ion Transport

Aqueous zinc-ion batteries (AZIBs) are increasingly being acknowledged as a promising candidate to safely power large-scale energy storage systems and portable devices. However, the development of effective separator materials remains a significant challenge due to issues such as harmful dendrite growth on zinc (Zn) anodes and parasitic side reactions in aqueous electrolytes. To address this challenge, we synthesize a manganese-coordinated cellulose nanofibril (Mn-CNF)-based separator for high-performance AZIBs. This separator affords enhanced ion transport channel, a large number of hydroxyl groups, and exceptional mechanical properties, with a tensile strength of 2.8 MPa and superior ionic conductivity of 5.14 mS·cm−1. These attributes collectively enhance Zn-ion transport, minimize nucleation overpotential for Zn, and accelerate the Zn deposition kinetics, thus significantly outperforming the untreated CNF separators. Consequently, the Zn||MnO2 battery with the Mn-CNF separator shows a marked improvement in the galvanostatic rate performance and cycling stability by effectively accelerating and optimizing Zn-ion transport. This study offers valuable insights into the development of efficient and reliable separators for advanced electrochemical energy storage technologies.

From Fundamentals to Practice: Electrolyte Strategies for Zinc‐Ion Batteries in Extreme Temperature

ABSTRACTIn the pursuit of advanced energy storage technologies that promote sustainable energy solutions, zinc‐ion batteries (ZIBs) have emerged as a promising alternative to lithium‐ion batteries due to their abundance, safety, and environmental advantages. However, the failure mechanisms of ZIBs under extreme temperatures are still not fully understood, presenting significant challenges to their development and commercialization. Therefore, innovative strategies are essential to enhance their adaptability to temperature extremes. In this review, we first explore the thermodynamic and kinetic aspects of performance degradation under extreme temperatures, focusing on key factors such as ion diffusion and redox processes at electrode interfaces. We then comprehensively summarize and discuss the existing approaches for various electrolyte types, including aqueous, nonaqueous, and solid state. Finally, we highlight the key challenges and future prospects for ZIBs operating under extreme temperature conditions. The insights presented in this review are expected to accelerate the advancement of ZIBs and facilitate their practical implementation in large‐scale energy storage systems.

Tailoring flower-like NiCo LDH/MoS2/HPC ternary hierarchical heterostructures electrodes with enhanced energy density for aqueous asymmetric supercapacitor

The imperative quest for renewable energy sources and advanced energy storage technologies has arisen amidst the escalating perils of climate change and dwindling fossil fuel reserves. In the realm of energy storage technologies, asymmetric supercapacitor (ASC) has garnered significant attention owing to its high energy density and power density. In the quest for advanced electrode materials for ASC, the integration of 2D layered heterostructures on hierarchical porous carbon (HPC) substrates has emerged as a promising approach to enhance the electrochemical performance. Herein, a highly innovative hierarchical NiCo LDH/MoS2/HPC heterostructure was successfully synthesized using a simple two-step hydrothermal method for the electrode materials of ASC. Benefiting from the unique hierarchical heterostructure of NiCo LDH/MoS2/HPC composite and the synergistic effect between the components, it reveals an exceptional specific capacitance of 2368 F/g at 0.5 A/g in a three-electrode system, which significantly exceeds that of conventional supercapacitor electrodes. Additionally, the ASC device of NiCo LDH/MoS2/HPC//HPC achieves remarkable specific capacitance of 236 F/g at 0.5 A/g and an impressive energy density of 84 Wh/kg at a power density of 400 W/kg, as well as superior cyclic stability. This study not only demonstrates the effectiveness of incorporating MoS2 and NiCo LDH into a carbon-based framework for supercapacitor applications but also opens avenues for designing more efficient energy storage devices.

Probing the potential of type V Deep eutectic solvents as sustainable electrolytes

The increasing interest within the scientific community in environmentally friendly solvents has led to a focus on Deep Eutectic Solvents (DES), which have natural components. DES are viewed as alternatives to traditional organic solvents and have the potential to be used as electrolytes. For the first time, transport properties of four Type V Deep Eutectic Salt Solutions (DESS) were accessed to investigate the potential of this technology, selecting precursors ranked as excellent in Eco-Scale metrics. The DESS were composed of terpene and trioctylphosphine oxide (TOPO), and varying concentrations of lithium bis(trifluoromethane)sulfonimide (LiTFSI), and their properties were assessed through self-diffusion, viscosity, density, and conductivity measurements. While Type V DESS are capable of dissolving significant amounts of LiTFSI (up to 30 % molar), their ionic conductivity is low, with values ranging from 3.6·10−3 to 9.3·10−2 mS·cm−1 at 25 °C, thus limiting their suitability as electrolytes, for instance, for lithium-ions batteries applications. Similar diffusion coefficients for Li+ and TFSI− ions suggest the formation of long-lived ion pairs moving as a neutral species. Therefore, future research aims to introduce additives to disrupt contact ion pairs and enhance transport properties, leveraging the sustainable appeal of DES and their use in advanced energy storage technologies.

Fast kinetics for lithium storage rendered by Li3VO4 nanoparticles/porous N-doped carbon nanofibers

Li3VO4 (LVO) has been recognized as an alternative anode material for lithium-ion batteries (LIBs) because of its appropriate lithium storage potential and capacity merits. However, its practical application is seriously hindered by slow reaction kinetics stemming from poor electronic conductivity. Herein, Li3VO4/porous N-doped carbon nanofibers (LVO/PNC NFs) are firstly designed and fabricated via an electrospinning method, utilizing the thermal decomposition characteristics of polylactic acid (PLA). The porous N-doped carbon nanofibers provide efficient electrolyte diffusion paths and facilitate ion transport. In addition, LVO nanoparticles are uniformly dispersed along the nanofibers to effectively inhibit particle aggregation. The obtained LVO/PNC NFs are evaluated as anodes for LIBs and deliver high reversible capacity of 768 mAh g−1 after 300 cycles at 0.2 A g−1, along with excellent rate capability (average capacity of 355 mAh g−1 at 8 A g−1 after 6 periodic rate testing) and long cycling life (286 mAh g−1 after 2000 cycles at 4 A g−1). The special porous nanofiber represents an effective strategy for improving the electronic conductivity, inhibiting particle aggregation, and ensuring rapid ion/charge transport towards advanced energy storage technologies.

Electroactive ferrocene-based ionic liquids: transport and electrochemical properties of their acetonitrile solutions

The increasing global demand for energy stimulates the development of advanced energy storage and conversion technologies. Modification of electrolyte with redox-active additives is a promising way to enhance the electrochemical performance of energy storage devices. In this work new electroactive ferrocene-based ionic liquids (Fc-ILs) (N-methyl-N-(ferrocenylmethyl)piperidinium bis(trifluoromethanesulfonyl)imide [PipFcMe][NTf2], N-methyl-N-(ferrocenylmethyl)pyrrolidinium bis(trifluoromethanesulfonyl)imide [PyrFcMe][NTf2], N-ethyl-N-(ferrocenylmethyl)pyrrolidinium bis(trifluoromethanesulfonyl)imide [PyrFcEt][NTf2]) were synthesized. The structure of the Fc-ILs was confirmed by NMR and XRD. [PipFcMe][NTf2] and [PyrFcMe][NTf2] demonstrated nearly similar crystal structures consisting of cation and anion columns, while alternating cation and anion layers are stacked in the [PyrFcEt][NTf2] crystal. The effects of the Fc-IL mole fraction and temperature on the transport properties of the acetonitrile solutions of the Fc-ILs have been established. The highest electrical conductivities of the [PipFcMe][NTf2], [PyrFcEt][NTf2] and [PyrFcMe][NTf2] solutions calculated using the Casteel-Amis equation were, respectively, 38.06 ± 0.63, 40.34 ± 0.93 and 41.09 ± 0.58 mS/cm at 348.15 K. The activation energies of conductivity were calculated using the Arrhenius and Vogel-Fulcher-Tamman approaches. The Fc-ILs demonstrated a high electrochemical stability range up to 4.67 V. The introduction of electron-withdrawing substituents into the cyclopentadienyl ring of Fc-ILs shifted the half-wave potential to the positive direction. The diffusion coefficients were calculated using the Randles–Ševčík equation for a quasi-reversible process.

Graphene-Based Materials in Energy Storage and Conversion Devices

Global energy demand and environmental concerns have grown increasingly over the years. To solve these problems, advanced energy storage and conversion technologies are essential. This work explores the applications of graphene-based materials to enhance the performance of lithium-ion batteries, supercapacitors, and solar cells. In lithium-ion batteries, graphene significantly improves electrical conductivity, mechanical stability, and energy capacity, thereby improving battery performance. Likewise, in supercapacitors, graphene-based electrodes exhibit excellent specific capacitance and energy density, which are crucial for high-power applications. In solar cells, graphene improves photoelectric conversion efficiency and stability, especially in perovskite and ZnO/Si heterojunction solar cells. However, the high cost and complexity of producing graphene limit its widespread use. Future research should focus on developing cost-effective production methods, optimizing graphene properties through doping, exploring composite materials, and expanding graphene applications in sustainable energy and environmental fields. This work provides an overview of current progress and suggests directions for future research in this area.

Predicting interfacial tension in brine-hydrogen/cushion gas systems under subsurface conditions: Implications for hydrogen geo-storage

Underground hydrogen storage (UHS) critically relies on cushion gas to maintain pressure balance during injection and withdrawal cycles, prevent excessive water inflow, and expand storage capacity. Interfacial tension (IFT) between brine and hydrogen/cushion gas mixtures is a key factor affecting fluid dynamics in porous media. This study develops four machine learning models— Decision Trees (DT), Random Forests (RF), Support Vector Machines (SVM), and Multi-Layer Perceptrons (MLP)—to predict IFT under geo-storage conditions. These models incorporate variables such as pressure, temperature, molality, overall gas density, and gas composition to evaluate the impact of different cushion gases. A group-based data splitting method enhances the realism of our tests by preventing information leakage between training and testing datasets. Shapley Additive Explanations (SHAP) reveal that while the MLP model prioritizes gas composition, the RF model focuses more on operational parameters like pressure and temperature, showing distinct predictive dynamics. The MLP model excels, achieving coefficients of determination (R2) of 0.96, root mean square error (RMSE) of 2.10 mN/m, and average absolute relative deviation (AARD) of 3.25%. This robustness positions the MLP model as a reliable tool for predicting IFT values between brine and hydrogen/cushion gas (es) mixtures beyond the confines of the studied dataset. The findings of this study present a promising approach to optimizing hydrogen geo-storage through accurate predictions of IFTs, offering significant implications for the advancement of energy storage technologies.

Mass Transportation Facilitated Porous Fe/Co Dual‐Site Catalytic Cathodes for Ultrahigh‐Power‐Density Al–Air Fuel Cells

AbstractThe development of oxygen‐dependent fuel cells is frequently hindered by the high cost of cathode materials and the sluggish kinetics of the oxygen reduction reaction (ORR). It is thus crucial to explore low‐cost and high‐activity catalysts with accelerated mass transport. Here, a high‐throughput screening method is developed by integrating an explicit solvation model with machine learning potential‐based molecular dynamics simulations, which enables the efficient evaluation of a vast array of diverse diatomic combinations and ultimately identifying Fe–Co dual‐atomic sites as the optimal ORR electrocatalysts. The superior electrocatalytic performance of the diatomic Fe/Co sites loaded on 3D‐interconnected ordered macroporous carbon (FeCo‐3DMNC) is experimentally verified, achieving high ORR activity with half‐wave potentials of 0.806 V in acidic and 0.905 V in alkaline environments. Additionally, innovative hybrid acid/alkali aluminum–air fuel cells (hA/A‐AAFCs) incorporating FeCo‐3DMNC as the cathode catalyst demonstrate a notably high open‐circuit voltage of 2.72 V and a record‐breaking power density of 827 mW cm−2, significantly outperforming conventional alkaline aluminum–air fuel cells. This work marks a significant advancement by combining cutting‐edge computational screening with rigorous experimental validation to develop promising electrocatalysts, potentially paving the way for the advanced energy storage and conversion technologies.

A Multielectron and High-Potential Spirobifluorene-Based Posolyte for Aqueous Redox Flow Batteries.

The rising energy demand driven by human activity has posed pressing challenges in embracing renewable energy, necessitating advances in energy storage technologies to maximize their utilization efficiency. Recent studies in aqueous organic redox flow batteries have focused primarily on the development of organic negative electrolytes, while the progress in organic positive electrolytes remains constrained by limitations in their redox potentials and effective electron concentrations. Herein, we report a spatially twisted chlorinated spirobifluorene ammonium salts (CSFAs), created through an unexpected green chlorination-protection pathway during the initial cycling in the flow battery cell, utilizing chloride ions from counterions in aqueous solution. The chlorinated, nonplanar spiral structure of CSFAs possesses a one-step four-electron transfer electrochemical property and offers exceptional resistance to nucleophilic attacks, exhibiting an unprecedented redox potential as high as 1.05 V (vs. SHE). A full redox flow battery based on CSFA-Cl (chloride ions as the counter ions) with 1.4 M electron concentration achieved an average coulombic efficiency exceeding 99.4 % and a capacity utilization reaching 95 % of the four-electron capacity for a stable cycling over 250 cycles (~22 days). The present work exemplifies the use of side reactions to develop new redox species, which can be extended to create more structurally versatile energy storage materials.

Fluorinated ester additive to regulate nucleation behavior and interfacial chemistry of room temperature sodium-sulfur batteries

Room temperature sodium-sulfur (RT Na-S) batteries are considered as advanced energy storage technology due to their low cost and high theoretical energy density. However, challenges such as the growth of sodium dendrite and dissolution of sodium polysulfides significantly hinder the electrochemical performance. Herein, we developed a propylene carbonate (PC)-based electrolyte with Methyl 2-Fluoroisobutyrate (MFB) as an additive. The ester group in the MFB additive is capable of participating in and reconfiguring the coordination of their Na+ solvated structures, thereby lowering the desolvation barrier and regulating the Na anode’s interfacial reaction and nucleation behavior. The polar C−F bond at the other end helps to reduce the lowest unoccupied molecular orbital (LUMO) energy of the MFB additive, enabling the preferential decomposition of MFB to form the F-rich inorganic phase strong polar solid electrolyte interphase (SEI), contributing to the inhibition of Na dendrite growth, the accumulation of dead Na. In addition, NaF-riched cathode electrolyte interphase (CEI) was also observed on sulfur-based cathode, which can effectively inhibited the shuttle effect. Consequently, the developed RT Na-S battery exhibit excellent electrochemical performance.

Constructing hybrid nitrogen/oxygen-rich surface and hierarchically porous in lignite-based activated carbons as supercapacitor electrode by in-situ soda ash activate strategy

Coal-based activated carbon materials have the limitations of low specific surface area and limited ion mobilization rate, restricting their practical applications. In this study, porous coal-based activated carbon electrodes were prepared via chemical activation using lignite as a precursor for electrochemical energy storage. Using response surface methodology (RSM), the optimal conditions for preparing porous lignite-based activated carbon were identified: an activation temperature of 856 °C, an activation time of 2.6 hours, and a Na2CO3-coal mass ratio of 4.1:1. The pure alkali carbonization process enriched the activated carbon's three-dimensional pore structure, creating numerous ion-transport channels. The best sample (CAC-3) achieved a surface area of 1847.3 m2 g−1. Process optimization enhanced its electrochemical performance, resulting in a specific capacitance of 219.7 F g−1 at 1 A g−1. It maintained good cycling performance after 5000 cycles in a 6 M KOH aqueous solution at a current density of 10 A g−1. In a two-electrode system, the specific capacitance was 175.3 F g−1 at a current density of 1 A g−1. This study offers new insights for advanced energy storage technologies.

Corrosion evaluation of austenitic stainless steels in Li2CO3-K2CO3 eutectic salt for thermal energy storage

Molten carbonate salt is one of the promising candidates for high-temperature thermal energy storage tailored towards advanced pumped-thermal energy storage and next generation concentrated solar power technologies. However, severe corrosion of structural materials exposed to molten carbonate salts poses one of the most pivotal threats in terms of limiting their large-scale application at ever-escalating temperatures. Here, we elaborate the compatibility of three commercial austenitic stainless steels specifically SS310, SS316L and Incoloy 625 with Li2CO3-K2CO3 (28–72 wt%) eutectic salt. The corrosion behavior and corrosion mechanism of Fe-Cr (SS316L), Fe-Cr-Ni (SS310) and nickel-based (In625) alloys at 600 °C in air were also investigated. It revealed that SS310 exhibited better corrosion resistance compared to SS316 and In625, with weight loss of 23.8 mg/cm2 and corrosion rate of 522 μm/year after 500 h of exposure at 600 °C. This implies that higher Ni content of the alloy may not necessarily improve the corrosion resistance, it is associated with the basicity of the molten and the solubility of Ni salt in the melt. ICP analysis indicated that the salts exposed to SS310 and In625 at the same exposure time both had nearly 11 times more Ni than that exposed to SS316. Precisely, it is related to the behavior of the Cr-enriched zones formed in the corrosion layers of different alloys. The corrosion mechanism of SS310 specimens in molten carbonate can be generally divided into the following steps: (i) selective oxidation of the metal elements and lithiation reactions of the metal oxides to generate a passivation scale, (ii) an ever-growing middle transition scale consisted of mixed metal oxides and lithium-containing compounds, (iii) cracking and peeling off of the corrosion scale.

Utilization of NiO-rGO Nanoarchitectures-Based Composite Electrodes for High-Performance Electrochemical Applications

The urge to transition from fossil fuels to sustainable energy solutions has driven the exploration of advanced energy conversion and storage technologies. In this context, supercapacitors have garnered substantial interest for their high cyclic life span and power density. This study presents the facile synthesis of NiO and NiO/rGO composites (NO-I, NO-II, and NO-III) for battery-type applications, with a focus on their structural, morphological, and electrochemical characterizations. The results indicate the successful fabrication of crystalline materials with notable porosity in NO-III. Electrochemical analysis reveals battery-type behavior, with an inverse relationship between specific capacity (Q) and scan rates. Galvanostatic charge-discharge (GCD) measurements highlight enhanced charge storage capability, particularly in NO-III. GCD results showed the maximum values for (Q = 288 Cg−1), energy density (E = 36.12 Wh kg−1), and power density (P = 3.06 kW h−1) at 1.7 Ag−1 for NO-III, underscoring its potential for advanced energy storage systems.

Improvement of rate capability and cycle life of Na-NiCl2 battery via designing a graphene anchoring porous nickel nanostructures as cathode

The integration of renewable energy with advanced energy storage technologies is essential. The sodium-based batteries, particularly sodium-nickel chloride (Na-NiCl2) batteries, show promise due to the abundance and low redox potential of sodium (−2.7 V vs. SHE). Despite their advantages in terms of cost, safety, and high efficiency, the improvement of rate and cycling performance of Na-NiCl2 batteries remains a challenge. To address this issue, a Ni nanostructure-supported reduced graphene oxide (RGO) composite is synthesized and combined with NaCl to serve as the cathode material for Na-NiCl2 batteries. Benefiting from the strong anchoring function of RGO, the growth of Ni is inhibited. As a result, the obtained cathode exhibits a notable specific capacity of 132.7 mAh/g at a high rate of 0.6C, along with excellent Coulombic efficiency of 100 % over 500 cycles and high energy efficiency (95.8 %). In addition, the outstanding conductivity, high specific surface area and abundant pore distribution of Ni@RGO contribute to enhanced conversion reaction and ion diffusion, and thus promoting rate capability. In contrast, the pure Ni nanosheets-based (Ni NSs) cathode is subjected to serious grain growth, which leads to poor rate performance and rapid capacity fading. By introducing conductive framework of RGO and constructing porous Ni nanostructure, the rapid electrons transport and diffusion of ions is achieved, and thus presenting the exceptional electrochemical properties.

Thermodynamic and Exergoeconomic Analysis of a Novel Compressed Carbon Dioxide Phase-Change Energy Storage System

As an advanced energy storage technology, the compressed CO2 energy storage system (CCES) has been widely studied for its advantages of high efficiency and low investment cost. However, the current literature has been mainly focused on the TC-CCES and SC-CCES, which operate in high-pressure conditions, increasing investment costs and bringing operation risks. Meanwhile, some studies based on the phase-change CO2 energy storage system also have had the disadvantages of low efficiency and the extra necessity of heat or cooling sources. To overcome the above problems, this paper proposes an innovative compressed CO2 phase-change energy storage system. During the energy charge process, molten salt and water are used to store heat with a smaller temperature difference in heat exchangers, and high-pressure CO2 is reserved in liquid form. During the energy discharge process, throttle expansion is applied to realize the evaporation at room temperature, and CO2 absorbs the reserved heat to improve the power capacity in the turbine and the system energy storage efficiency. The thermodynamic and exergoeconomic studies are performed firstly by using MATLAB. Then, the parametric study based on energy storage efficiency, system unit product cost, and exergy destruction is analyzed. The results show that energy storage efficiency can be improved by lifting liquid CO2 pressure as well as compressor and turbine isentropic efficiencies, and CO2 evaporation pressure has the optimal pressure point. The system unit product cost can be reduced by decreasing liquid CO2 pressure and compressor isentropic efficiency, while CO2 evaporation pressure and turbine isentropic efficiency both have optimal points. Finally, the optimization of two performances is performed by NSGA-II, and they can reach 75.30% and 41.17 $/GJ, respectively. Moreover, the optimal energy storage efficiency is obviously higher than that of other energy storage technologies, indicating the great advantage of the proposed system. This study provides an innovative research method for a new type of large-scale energy storage system.

Advancements in Asymmetric Supercapacitors: From Historical Milestones to Challenges and Future Directions.

Numerous challenges, like the uninterrupted supply of electricity, stable and reliable power, and energy storage during non-operational hours, arise across various industries due to the absence of advanced energy storage technologies. With the continual technological advancements in portable electronics, green energy, and transportation, there are inherent limitations in their innovative production. Thus, ongoing research is focused on pursuing sustainable energy storage technologies. An emerging solution lies in the development of asymmetric supercapacitors (ASCs), which offer the potential to extend their operational voltage limit beyond the thermodynamic breakdown voltage range of electrolytes. This is achieved by employing two distinct electrode materials, presenting an effective solution to the energy storage limitations faced by ASCs. The current review concentrates on the progression of working materials to develop authentic pseudocapacitive energy storage systems (ESS). Also, evaluates their ability to exceed energy storage constraints. It provides insights into fundamental energy storage mechanisms, performance evaluation methodologies, and recent advancements in electrode material strategies. The review approaches developing high-performance electrode materials and achieving efficient ASC types. It delves into critical aspects for enhancing the energy density of ASCs, presenting debates and prospects, thereby offering a comprehensive understanding and design principles for next-generation ASCs in diverse applications.

A reinforcement learning method for two‐layer shipboard real‐time energy management considering battery state estimation

AbstractIncreasing global environmental concerns encourage a continuous reduction in carbon emissions from the shipping industry. It has become an irreversible trend to replace traditional fossil fuels with advanced energy storage technology. However, an improper energy management leads to not only energy waste but also undesired costs and emissions. Accordingly, the authors develop a two‐layer shipboard energy management framework. In the initial stage, a shipboard navigation planning problem is formulated that considers battery state estimation and is subsequently solved using particle swarm optimisation to obtain an optimal speed trajectory. To track the scheduled speed, a reinforcement learning method based on a deep Q‐Network is proposed in the second stage to realise real‐time energy management of the diesel generator and energy storage system. This approach ensures that the state of charge remains within a safe range and that the performance is improved, avoiding excessive discharge from the energy storage systems and further enhancing the efficiency. The numerical results demonstrate the necessity and effectiveness of the proposed method.

Architecting MxNy-MOF@MXene composites for excellent supercapacitor electrodes

The increasing demand for efficient energy storage systems has prompted the exploration of novel electrode materials, such as bimetallic metal-organic frameworks (MOFs). This study examines the synthesis of a variety of bimetallic MxNy-MOF materials, including Ni1Co1-MOF, Ni1Co3-MOF, Ni3Co1-MOF, Cu1Co1-MOF, and Ni1Cu1-MOF, as well as their integration with MXene to produce MOF@MXene composite electrode materials for supercapacitors. These MxNy-MOF materials display distinct morphologies and uniform particle sizes. MXene serves as an effective substrate, enhancing the surface coverage with the MOF phase. In interactions with MXene, Co2+ and Cu2+ demonstrate stronger binding than Ni2+, which prefers binding with ligands. Electrochemical testing reveals that Ni and Co-based composites, particularly Ni1Co1-MOF@MXene, exhibit superior performance and achieving a high specific capacitance of 1493.6 F g−1 at 1 A g−1. These materials also show impressive rate performance and cycle stability, with a retention of 57.2 % after 5,000 cycles. An all-solid-state flexible supercapacitor using Ni1Co1-MOF@MXene demonstrates an energy density of 73.9 Wh·kg−1 at a power density of 750 W·kg−1, maintaining 81.8 % capacity and 97 % Coulombic efficiency after 10,000 cycles. The energy storage mechanism primarily involves Faradaic redox reactions of Co2+/Co3+ and Ni2+/Ni3+, coupled with OH- adsorption/desorption processes. This study not only elucidates the kinetic dynamics and storage mechanisms of these composite materials but also highlights their potential applications in advanced energy storage technologies.