Applications In Storage Systems Research Articles

Storage Is the New Black: A Review of Energy Storage System Applications to Resolve Intermittency in Renewable Energy Systems

As the need for more sustainable methods of power generation becomes increasingly apparent due to the planet’s ever-deteriorating conditions, the quest for sustainable power generation intensifies. Among the options for sustainable power generation, the utilization of solar and wind power in large-scale applications is problematic due to the intermittent nature of their sources. Multiple solutions exist to counteract this intermittency, but energy storage systems are the most appealing. This article reviews the intermittency in renewable energy systems that rely on solar and wind, and how energy storage systems are utilized to mitigate this issue. While energy storage systems integrated into solar and wind power generation systems exhibit promising synergy and benefits, their full implementation is still hindered by a variety of challenges, which opens different fields of research to circumvent these challenges.

Extreme Environment-Adaptable and Ultralong-Life Energy Storage Enabled by Synergistic Manipulation of Interfacial Environment and Hydrogen Bonding

The broad applications of energy storage systems have brought improving demands for stable electrodes with robust tolerance to extreme environmental challenges. MXenes show promising pseudocapacitive behaviors, however, the poor thermodynamical and mechanical stability makes them unfavorable for applications under complex and harsh environments. Herein, we break these limitations by aramid nanofibers (ANF)-driven interfacial nanofilling and hydrogen-bonds effects in MXenes. Theoretical and experimental results unveil that ANF with unique polarity preferentially interacts with H2O molecules and forms hydrogen bonding networks to restrain oxidative and mechanical attack toward MXene, at the same time, the nanofilling enables interfacial mass transport intensification for increment in redox dynamics. As such, the synergistically coupled ANF-MXene microstructure (AM) unlocks superior mechanical properties for facing hash forces, i.e., tensile strength of 115.2 MPa and toughness of 1.8 MJ m-3, and an ultra-long cycling life with a capacitance retention of 90.7% after 40,000 cycles. Besides, the effective IR thermal camouflage performance (IR-emissivity: 20.9%) further renders the power supply working invisibly after fast charge/discharge-driven heat generation. Moreover, the performances can be well maintained when subjected to strong acid/alkali, high-temperature (200°C), and cryogenic (-196°C) treatments. These results highlight the key role of interfacial species synergy in accelerating versatile and robust energy applications.

Mechanistic study on moisture exposure of Ti-based layered oxides for sodium storage applications

The air stability and moisture sensitivity of titanium-based layered negative electrode materials for sodium storage play a critical role in their practical applications for advanced energy storage systems.

Designing Electroless Deposited RuO2 Thin Films for Laminated Quasi‐Solid‐State Symmetric Supercapacitor

AbstractProducing energy storage electrodes with exceptional performance using pseudocapacitive materials presents significant challenges. This study introduces a binder‐free, economical, and scalable method for the synthesis of a thin film of ruthenium oxide (RuO2) suitable for symmetric supercapacitors through electroless deposition. The influence of annealing temperature (373, 473, 573, and 673 K) on electrochemical performance is investigated. The RO‐573 thin film electrode demonstrated an impressive specific capacitance of 1006 F g−1 at a scan rate of 10 mV s−1. Additionally, a laminated quasi‐solid‐state symmetric device has been developed, showcasing a remarkable specific capacitance of 198 F g−1, ultrahigh energy density of 59.01 Wh kg−1, and a power density of 2.4 kW kg−1. The laminated, symmetric, quasi‐solid‐state supercapacitor device demonstrates impressive stability over 10,000 cycles, achieving a retention rate of 92%. The characteristics and design of laminated quasi‐solid‐state symmetric supercapacitors render them highly appropriate for real‐time applications in advanced energy storage systems.

What is the potential of walnut shell-derived carbon in battery applications?

The environmental implications of utilizing walnut shells (WSs) as a material for energy storage are complex, balanced between advancing technologies and improving efficiency. This review aims to address, for the first time, environmental concerns and health effects associated with this material by conducting an in-depth analysis of carbon materials derived from waste management systems. Beginning with a reevaluation of the structural characteristics, cellular morphology, and physicochemical properties of WSs, this study explores their potential for the efficient synthesis of carbon. By examining various methods for the production of WS-derived materials such as hard carbon, we demonstrate the multifaceted nature of WS biomass as a resource. Subsequently, we shift our focus to ion storage mechanisms in the carbon source (C-S), including storage sensitivity, ion intercalation in micropores, and layer intercalation. An electrochemical analysis of the carbon source reveals its potential applications in energy storage systems. Furthermore, life cycle analysis was employed to assess the environmental impact and economic viability of WS utilization. The findings of the analysis suggest that one of the most valuable attributes of WSs is their potential for creating more environmentally sustainable materials, encouraging researchers to promote the use of green components in sodium batteries. This review underscores, for the first time, the significance of WSs in the field of carbon energy storage and their potential to enhance future prospects. The substantial opportunities in this area warrant further research and development, highlighting the relevance of WS-derived materials in advancing sustainable energy storage solutions.

Unlocking the Ultrafast Deposition Kinetics within Bi-Tailored Core-Shell Structured Carbon Nanofibers for Highly Efficient and Ultrastable Sodium Metal Batteries.

Sodium metal anodes (SMA), featuring high energy content, low electrochemical potential and easy availability, are a compelling option for sustainable energy storage. However, notorious sodium dendrite and unstable solid-electrolyte interface (SEI) have largely retarded their widespread implantation. Herein, porous amorphous carbon nanofiber embedded with Bi nanoparticles in nanopores (Bi@NC) was rationally designed as a 3D host for SMA. In situ and ex situ characterizations, along with theoretical simulations unlock that the in-situ formed Na-Bi alloy significantly accelerates sodium metal nucleation and sodium ion diffusion kinetics, enabling uniform sodium plating within the void spaces and a stable SEI outside the carbon nanofiber. Particularly, the Bi@NC electrode achieved a high coulombic efficiency of 99.99 % at 3 mA cm-2 and 3 mAh cm-2 in half-cell tests, a cycle life of 1000 hours at 5 mA cm-2 and 10 mAh cm-2, and sustained performance over 600 cycles under harsh conditions under 30 mA cm-2 and 3 mAh cm-2 within symmetrical cells. The full battery assembled with a Na3V2(PO4)3@C cathode and Bi@NC anode delivered long-term cyclability over 800 cycles, demonstrating its potential for flexible application of sodium-based energy storage systems. This work highlights the Bi@NC electrode as a promising candidate for high-performance and flexible sodium metal batteries.

Impact of Shock Compression on the Photovoltaic Performance of NiCo2O4 Nanoparticles

ABSTRACTSpherical‐shaped nickel cobaltite (NC) nanoparticles were synthesized via a simple sol–gel technique and calcined at 600°C. X‐ray diffraction (XRD) analysis revealed significant changes in crystallite size, with an average of 23 nm for the control sample and variations observed after 50 shockwaves. Fourier transform infrared spectroscopy (FTIR) confirmed metal‐oxygen stretching, indicating structural integrity. UV–visible absorption studies showed changes in the optical band gap, which increased after shock treatments, suggesting bandgap tunability for optoelectronic and photovoltaic applications. The material exhibited good optical absorption up to 600 nm, making it suitable for light‐harvesting devices. Vibrating sample magnetometry (VSM) detected shifts in dipole moments and magnetic saturation, with all samples displaying paramagnetic behavior. The shock‐treated samples showed enhanced magnetic properties, which could be useful in magnetic storage devices. The combined tunability of bandgap and magnetic properties via shock wave treatment underscores the potential of these nanoparticles for applications in photovoltaics, spintronics, and energy storage systems.

Design and Implementation of a High-Performance VLSI Architecture for Canonical Huffman Encoding

A key component of contemporary computer systems, data compression makes it possible for information to be stored and transmitted efficiently. A popular technique for lossless data compression, Huffman coding can drastically cut down on data size without sacrificing intensity. But conventional Huffman encoding techniques can have scalability and speed issues, especially when used in hardware. A high-throughput Very Large-Scale Integration (VLSI) design for a Canonical Huffman Encoder is shown in this study. To accomplish quick and effective encoding, the suggested approach makes use of parallel processing and improved algorithms. The system's use of the canonical Huffman algorithm lowers computational complexity and streamlines hardware implementation without sacrificing compression performance. The architecture incorporates real-time operation-optimized modules for frequency analysis, code generation, and symbol encoding. Results from simulations show that the suggested design achieves significantly higher throughput compared to conventional approaches, making it suitable for applications in data storage, multimedia, and communication systems. This study contributes to advancing VLSI designs for high-performance hardware Key Words: Data Compression, Huffman Coding, Lossless Compression, Very Large-Scale Integration (VLSI), Canonical Huffman Encoder, High-Throughput Encoding, Parallel Processing, Efficient Encoding, Hardware Implementation, Computational Complexity, Code Generation, Symbol Encoding, Frequency Analysis, Real-Time Operation, Throughput Optimization, Multimedia Systems, Communication Systems, Data Storage, Hardware Architecture, VLSI Design, Performance Optimization, Simulations, Compression Performance, Hardware Design, Throughput Enhancement, System-Level Optimization, Power Efficiency, Resource Management, Data Transfer Efficiency, Low-Cost Implementation.

A comparative study on exploring sputtered titanium nitride thin films for high-performance supercapacitors

Magnetron sputtered titanium nitride (TiN) thin films possessed desirable electrochemical and physical characteristics making them attractive candidates for supercapacitor electrodes. Herein, the electrochemical performance of TiN films prepared via direct and reactive sputtering methods is investigated as electrodes for supercapacitor. Microstructural analysis revealed distinct morphologies, topographies, and crystal structures for each film type, with reactively sputtered TiN (RS) displaying a pyramidal structure indicative of (111) orientation, whereas directly sputtered TiN (DS) exhibited a granular structure. Electrochemical techniques like cyclic voltammetry, galvanic charge-discharge, and electrochemical impedance spectroscopy clarified the charge storage mechanisms and capacitance behavior. RS exhibited a quasi-rectangular CV profile with pseudo-capacitive behavior with low charge transfer resistance and peak specific capacitance of 90 mF cm−2 along with superior cyclic stability and ion conductivity. Supercapattery configuration was setup to validate those findings using reactive sputtered thin films. It demonstrated enhanced capacitance retention and low charge transfer resistance, highlighting their potential for practical applications in energy storage systems.

Poly(Ionic) Liquid-Enhanced Ion Dynamics in Cellulose-Derived Gel Polymer Electrolytes.

Gel polymer electrolytes (GPEs) are regarded as a promising alternative to conventional electrolytes, combining the advantages of solid and liquid electrolytes. Leveraging the abundance and eco-friendliness of cellulose-based materials, GPEs were produced using methyl cellulose and incorporating various doping agents, either an ionic liquid (1-Butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide [Pyr14][TFSI]), its polymeric ionic liquid analogue (Poly(diallyldimethylammonium bis(trifluoromethylsulfonyl)imide) [PDADMA][TFSI]), or an anionically charged backbone polymeric ionic liquid (lithium poly[(4-styrenesulfonyl)(trifluoromethyl(S-trifluoromethylsulfonylimino) sulfonyl) imide] LiP[STFSI]). The ion dynamics and molecular interactions within the GPEs were thoroughly analyzed using Attenuated Total Reflectance Fourier-Transform Infrared Spectroscopy (ATR-FTIR), Heteronuclear Overhauser Enhancement Spectroscopy (HOESY), and Pulsed-Field Gradient Nuclear Magnetic Resonance Diffusion (PFG-NMR). Li+ transference numbers (tLi+) were successfully calculated. Our study found that by combining slow-diffusing polymeric ionic liquids (PILs) with fast-diffusing lithium salt, we were able to achieve transference numbers comparable to those of liquid electrolytes, especially with the anionic PIL, LiP[STFSI]. This research highlights the influence of the polymer's nature on lithium-ion transport within GPEs. Additionally, micro supercapacitor (MSC) devices assembled with these GPEs exhibited capacitive behavior. These findings suggest that further optimization of GPE composition could significantly improve their performance, thereby positioning them for application in sustainable and efficient energy storage systems.

Resistive switching and artificial synapses performance of co-evaporated Cs3Cu2I5 films

Perovskite memristors have garnered significant interest for their potential simulating artificial synapses; however, the presence of the toxic lead-based perovskites has hindered advancements in this field. In this work, a nontoxic, thickness-controllable Cs3Cu2I5 perovskite functional layer is synthesized through a dual-source vapor deposition for the Ag/Cs3Cu2I5/ITO memristor. The co-evaporation method shows advantages of various element, controllable atomic ratio and thickness, free impurity, and continuously uniform film. This device demonstrates an operating voltage of 1.2 V, a low power consumption of 0.013 W, a retention time exceeding 104 s, and an endurance of over 400 cycles. The synaptic behavior is emulated using the memristor, focusing on phenomena such as short-term potentiation and depression, paired-pulse facilitation, and spike-time-dependent plasticity. The migration of Na+ and Cl− ions, which occurs between the synaptic cleft and the postsynaptic membrane in biological synapses, is analogously represented by the movement of Ag+ ions between functional layer and the bottom electrode of the memristor. This process is further analyzed using the Hodgkin–Huxley neuron model. The Cs3Cu2I5-based memristor shows considerable promise for applications in storage systems and artificial synapses.

Performance study of integrated compressor/expander based on small-scale compressed air energy storage system

Compressed air energy storage will have good development prospects because of its exceptional safety and reliability, low economic cost, zero carbon emissions, and pollution-free environmentally friendly characteristics, which meet the needs of sustainable and green development. In view of the problems of large volume, great number of equipment, and poor flexibility of traditional compressed air energy storage equipment, this article built a compressed air experimental bench based on pneumatic motor and conducted integrated pneumatic motor compression/expansion experiments. The effects of key parameters such as speed, torque and current on the performance of pneumatic motor under different modes are investigated, providing reference for the application and promotion of small compressed air energy storage systems. The results indicate that in the expansion mode of the pneumatic motor, the total efficiency and power output of the motor can reach up to 14.01 % and 1257.87 W. Its high power output and economic operation are concentrated within the medium range of rotation speed and current, respectively, with a certain cooling effect achieved in this mode. In compression mode, the maximum output power of the motor can reach 3696.33 W, while the energy efficiency is up to 78.39 %. The operating parameters such as torque and current are basically positively correlated with the system performance parameters. The integrated system is flexible, saves space, and has certain feasibility.

Sustainable Binder Materials and Their Benefits for Li-Ion Batteries

Binder materials play an increasingly important role in battery technology; they have a substantial influence on the batteries performance and lifetime behavior. However, it is widely noticed that deficiencies in binder performance, as well as aging-related issues, significantly affected the resultant shortened life cycle of batteries.Established systems utilizing carboxymethyl cellulose (CMC) and polyvinylidene fluoride (PVDF) have fallen short of meeting the increasing requirements regarding poor elasticity and polarity, which are of importance for accommodating volume expansion and ensure adhesion. The adhesion plays a crucial role for the connection and conductivity not only within the electrode materials but also towards the current collectors and therefore is significant for battery performance. Different influencing factors on the polymer structure like mechanical shear stress during the dispersion process or the crosslinking behavior of the binder with the active material depending on the functional groups have an impact on the binder-material-interaction and therefore on adhesion and performance of the battery cell.The mechanical and electro physical tasks of the binder are very diverse and grow with the increase of new materials, as active materials e.g., and processing methods. However, the property profile of the binder is rarely adapted, ever through it contributes significantly to the performance of the binder cell. This research deals with sustainable battery processing by using e.g. biodegradable polymeric binder materials and the application in energy storage systems. The investigation of adhesion and cohesion characteristics of new binder systems were characterized with a combination of electrochemical impedance spectroscopy (EIS) to study the binder influence on the battery cell. Especially the aging of a battery connected to the binder is evaluated by EIS. The results lead to further interpretations on the adhesion ability and the failure patterns.Consequently, a comprehensive knowledge about binder behavior within a battery system and associated optimization of binder properties, which is imperative for achieving sustainable battery materials, is the goal for sustainable energy materials.

(Invited) Design and Synthesis of Heterostructured Anode Materials for Advanced Sodium-Ion Batteries

The transition toward carbon neutrality has accelerated the adoption of electric vehicles and large-scale energy storage systems, predominantly powered by lithium-ion batteries. However, concerns over the limited lithium resources necessitate exploring alternative battery systems. Sodium-ion batteries stand out due to the abundant supply and economic feasibility of sodium compared to lithium.This study focuses on developing high-capacity anode materials for sodium-ion batteries through the design of heterostructured composites. By combining conversion- or alloy-based active materials with a porous silicon oxycarbide (SiOC) nanocoating layer, we aim to address challenges such as volume changes, sluggish kinetics, and interfacial instability during battery cycling. Heterostructured composite anodes with a SiOC-based nanocoating layer were synthesized via controlled dispersion of precursors in silicon oil followed by heat treatment. Comprehensive physicochemical and electrochemical characterization, along with post-mortem analysis, elucidated how the heterostructure influenced battery performance. Our findings demonstrate improved electrochemical stability and enhanced sodium storage capacity attributed to the unique architecture of the heterostructured composites.This novel approach offers promising prospects for developing advanced anode materials capable of significantly enhancing the energy density and overall performance of sodium-ion batteries, thereby contributing to sustainable energy storage solutions for future applications in electric vehicles and grid-scale energy storage systems.

(Invited) Improvement in Dynamic Operational Stability of Alkaline Water Electrolysis

The significant advantages of alkaline electrolyzers, including their maturity, large capacity, and cost-effectiveness, have garnered considerable attention as viable applications for energy storage systems linked to renewable energy sources such as wind and solar. These attributes offer economic benefits for managing fluctuations in electrical loads by storing excess energy as hydrogen, serving as an efficient energy carrier, particularly in long-term and large-scale storage systems. However, the fluctuating loads stemming from renewable power sources can impact electrolysis performance and potentially affect overall durability. Here, we will discuss improvements in the dynamic operational stability of alkaline water electrolyzers (AWE), mainly focusing on the electrodes, analyzing degradation phenomena. This analysis was conducted from the perspective of material design disciplines, combined with computational engineering and X-ray spectroscopic analysis. The dynamic operational stability of the screened electrodes in alkaline solutions was evaluated using accelerated test protocols. Importantly, no significant oxygen & hydrogen evolution reaction performance degradation was observed after the lab-scale dynamic operation tests, and no structural deformation or metal ion dissolution were found to occur. Furthermore, these electrodes were scalable up to an area of 2,500 cm2 and could be evaluated in electrolyzer stacks of 100 kW or higher. We believe that enhancing poor kinetic efficiency and mitigating component degradation would extend the system's lifetime, thereby improving the economics of alkaline water electrolysis.

Improving Zn Anode Stability in Zn Ion Battery by Controlling Electrochemical Zn Growth with Organic Additives

Lithium-ion batteries (LIBs) are indispensable for storing electrical energy in portable electronics and electric vehicles, thanks to their high energy density, light weight, and excellent reversibility and cyclability. Despite their successful integration into various electronic devices, their application in Energy Storage Systems (ESS) with substantial capacities is hindered by safety concerns. This is because increasing the energy storage capacity inevitably leads to a higher volume of flammable organic solvents. Therefore, significant research efforts have been directed towards aqueous batteries to develop safer alternatives, including representative Zn-ion batteries (ZIBs). Compared to conventional LIBs, ZIBs offer cost-effectiveness, high safety, and environmental friendliness. However, the practical application of aqueous Zn ion batteries (AZIBs) is hindered by several issues, particularly concerning Zn dendrite growth, corrosion, and the hydrogen evolution reaction (HER) on the Zn anode side, which critically reduce the cyclability of ZIBs. To mitigate these challenges, several solutions have been proposed, including the modification of the Zn ion hydration structure, the use of water-in-salt electrolytes, and the addition of additives to modulate the properties of the Zn surface. This presentation will introduce organic additives aimed at controlling the electrochemical Zn growth to enhance the cyclability of the Zn anode. These organic additives influence both the kinetics of the Zn deposition/dissolution processes and the properties of Zn deposits. We will discuss the effect of organic additives on Zn growth and the cyclability of Zn||Zn symmetric cells based on the molecular structure and adsorption behavior of the additives. By considering all results, we will determine which functional group is critical for controlling Zn growth and suggest the optimal organic additive for AZIBs.

A Low-Cost Zn-Ion Hybrid Supercapacitors with High Energy Density

In recent years, hybrid supercapacitors with greater potential and improved energy density have been completed by combining some battery and supercapacitor type electrodes. According to some researchers’ research, “hybrid” supercapacitor systems are technically “asymmetric” supercapacitor systems since they are built on two separate supercapacitor type electrodes. The primary aim behind the development of a hybrid capacitor (HC) is to improve the energy density or specific energy of the device, which will significantly boost the storage property. Moreover, the use of an electrical double layer capacitor type electrode provides a large surface area, improving the electrode/electrolyte interaction region, and helps in the fast ion-adsorption process, which prevents the degradation of the battery-type electrode due to repeated charge-discharge cycles. A suitable combination of specific power (due to the EDLC electrode) and specific energy (due to the faradic electrode) could drastically enhance the stability and longevity of the hybrid supercapacitor device. The di/tri-valent metal ion (Mg2+, Zn2+, Ca2+, Al3+, etc.) hybrid capacitors have garnered considerable attention in recent years owing to their potential cost benefit and application in stationary storage systems, whose development is crucial for the mass-scale penetration of renewable energy technologies.Zinc‐ion hybrid supercapacitors (ZIHSs) may be the most promising energy storage device alternatives for portable and large‐scale electronic devices, as they combine the benefits of both supercapacitors and zinc‐ion batteries. ZIHSs are mostly based on battery-type Zn metal as an anode and physical adsorption-based carbon materials as the cathode. Porous carbon materials with high surface area, good electrochemical stability, low cost, high electronic conductivity and tuneable surface structure are deemed as promising cathode materials for ZIHSs. It is generally recognized that the micropores facilitate electrochemical energy storage, and mesopores can effectively reduce the ion diffusion distance and transport resistance. Therefore, the adjustment and optimization of porous carbons electrodes are of great significance to ZIHSs.This work provides some insight into the strategy for designing effective non-aqueous and aqueous Zn-ion hybrid supercapacitors. Electrochemical characteristics of Zn-ion hybrid supercapacitor cells based on non-aqueous 1 M acetonitrile (AN) or propylene carbonate (PC) electrolytes with addition Zn(BF4)2, zinc di[bis(trifluoromethylsulfonyl)imide] (Zn(TFSI)2) and zinc trifluoromethanesulfonate (Zn(OTf)2) have been studied. Very high energy and power densities (80 Wh kg−1 and 21.2 kW kg−1) have been measured for 1 M Zn(BF4)2/AN based Zn-ion based hybrid supercapacitors (Fig. 1a). Very good stability during 3,000 cycles of cells has been achieved demonstrating reasonably high energy efficiency value (66.8%) for Zn(TFSI)2/AN based ZIHS cell, decreasing in the order of electrolytes: Zn(TFSI)2/AN > Zn(BF4)2/PC > Zn(TFSI)2/PC > Zn(OTf)2/AN > Zn(BF4)2/AN. Some assembled ZIHSs had shown excellent cycling and energy stability over 20,000 cycles [1].Electrochemical behaviour of Zn cation based salts in various aqueous electrolytes (ZnSO4, Zn(BF4)2, Zn(TFSI)2, and Zn(OTf)2) has been studied in thin ZIHS cell and compared with Zn(ClO4)2 aqueous electrolyte based cell electrochemical characteristics. At moderate specific power value (10 kW kg− 1) noticeable decrease of specific energy has been established in the order of aqueous electrolytes: Zn(ClO4)2 ⩾ Zn(BF4)2 > Zn(OTf)2 > Zn(TFSI)2 > ZnSO4 (Fig. 1b). The stability of Zn-ion hybrid supercapacitor cells under study in aqueous electrolyte solutions has been tested using the long lasting (up to 10,000 cycles) constant current charge/discharge method and very good stability for Zn(OTf)2, Zn(ClO4)2 and ZnSO4 has been observed [2,3].Taking into account the cheap and environmental friendliness electrodes and electrolyte used, the results can be applied for assembling of the cheap high energy density hybrid supercapacitors for sustainable energy storage/recuperation complexes, combined with photovoltaic fields and/or wind electricity generating systems. Acknowledgements This work was supported by the Estonian Ministry of Education and Research (TK210, Centre of Excellence in Sustainable Green Hydrogen and Energy Technologies), Personal Research Grant PRG676 and R&D project EAG228. The experimental part of the research was partially co-funded by the Feasibility Fund of the University of Tartu Development Fund.

Lithium Battery Cathode Materials, Li-Rich Li-Fe-M-O, Based on Tetrahedrally-Coordinated Structure

The development of high-energy-density batteries with lithium (de-)intercalation reaction is one of the most promising solutions to realize electric vehicles and power storage system applications with long-term stability. The cathode materials exhibit smaller capacity than the anodes, which limits the energy density of the battery cells [1]. Consequently, the development of new cathode materials with higher capacity than previously reported is required. In the lithium 3d transition metal system, Li-rich materials based on tetrahedrally-coordinated structure, ex. Li5FeO4 and Li6CoO4, exhibited a reversible two lithium (de-)intercalation reaction over 350 mAh/g with mainly anionic redox [2,3]. The capacity was much higher than the practical cathode materials. Therefore, these Li-rich transition metal oxides with tetrahedrally coordinated structure have potential as high capacity cathode materials. In this study, Li-rich cathode materials based on tetrahedrally-coordinated structure were synthesized, and electrochemical properties in the lithium battery cell were characterized by electrochemical and structural investigations.One of the Li-rich transition metal oxides; Li5+x Fe1-x Mn x O4 was synthesized by solid state reaction [4]. Phase identification by X-ray diffraction (XRD) measurement was conducted using a diffractometer with Cu Kα radiation. Observation of particle morphology and elemental distribution was performed using scanning electron microscope (SEM) with energy dispersive X-ray spectroscopy (EDX). The prepared active material samples were mixed with Ketjen black as conductor and polytetrafluoroethylene as a binding agent using an agate mortar to prepare a composite electrode. A 2032-type coin cell was prepared using Li metal as the anode and 1 mol/dm3 LiPF6/ethylene carbonate:diethylene carbonate = 50:50 vol% as the electrolyte. Charge-discharge measurements were conducted in the voltage range of 1.7−3.9 V at 50 °C. The ball-milling process with acetylene black (AB) was applied before electrode fabrication to decrease the particle size of the prepared samples and achieve homogeneous electrical conduction in the composite electrode. The active material and AB were mixed with ZrO2 balls in a ZrO2 pot. A similar electrode fabrication process was conducted using a mixture of active material and AB.An antifluorite structured Li6MnO4-type phase with the small starting materials was obtained in the range between 0.6 and 1.0 composition. The amount of residual reagents decreased with increasing excess lithium content in the starting mixture. A single phase with an Li6MnO4-type structure was obtained for an excess lithium composition of 10 mol%. The particle size of the synthesized samples was about 50 µm, which is quite large compared with conventional cathode materials for lithium batteries. The as-synthesized Li5.6Fe0.4Mn0.6O4 exhibited first charge and discharge capacities of 680 and 300 mAh/g, respectively, with a large irreversible capacity of 380 mAh/g (coulombic efficiency = 44%). This indicates that the new iron-manganese composition with ordered antifluorite-type structure is lithium insertion/extraction-active although a large irreversible electrode reaction was observed.The ball milling process with AB provided that the particle size of the sample was decreased from ca. 50 µm to 1 μm, and a uniform distribution of Mn, Fe and C signals was realized for the mixture without any local signals. This suggests that a fine and homogeneous composite material composed of the active material and AB was obtained by the ball-milling process. The first discharge capacity of the Li5.6Fe0.4Mn0.6O4 electrode treated by ball-milling was 450 mAh/g. The coulombic efficiency was 60%. A reversible reaction continued to proceed with ca. 200 mAh/g after the following cycles. The differential capacity plots for the ball-milled Li5.6Fe0.4Mn0.6O4 (x = 0.6) at the second, third, and tenth cycles exhibited two pair of redox peaks at around 2.5 V and 3.2 V, which reveals that the lithium (de-)intercalation reaction successfully occurred after the 2nd cycle. A new iron-manganese based ordered antifluorite-type compound has potential as a high-capacity oxide cathode material and thus further investigation is required. Phase formation and electrochemical properties of the Li-rich materials based on tetrahedrally-coordinated structure including the other cation will also be discussed in the presentation. Acknowledgement: This work was financially supported by Tokuyama Science Foundation, Nippon Sheet Glass Foundation for Materials Science and Engineering, and JSPS KAKENHI Grant Number 24K01582.

Organic-inorganic hybrid cathode enabled by in-situ interface polymerization engineering boosts Zn2+ desolvation in aqueous zinc-ion batteries

Rechargeable aqueous zinc-ion batteries (RAZIBs) have attracted considerable attention for application in large-scale energy storage systems. However, the progress of RAZIBs has been hindered by the sluggish reaction kinetics and poor structural stability, which are closely associated with the desolvation process of hydrated Zn2+. To overcome these issues, an in situ interfacial polymerization strategy is proposed to uniformly germinate a polyaniline (PANI) layer on α-MnO2 and form an organic–inorganic hybrid cathode (MnO2@PANI). Theoretical calculations and experimental characterizations disclose that the polyaniline layer equipped with hydrophilic functional groups can effectively trap the active water molecules to break the strong attraction between H2O and Zn2+, thereby facilitating the desolvation process of hydrated Zn2+, and regulating the Zn2+ diffusion kinetics and electrode reaction kinetics on the cathode/electrolyte surface. Meanwhile, the irreversible phase evolution and dissolution of active species are largely suppressed due to the PANI shell protecting the α-MnO2 from the attack of active water molecules. As a consequence, the organic–inorganic hybrid cathode exhibits 401.9 mAh/g after 200 cycles at a current density of 0.5 A/g and long-term durability over 1000 cycles at a current density of 2.0 A/g without irreversible phase transformation. This work provides insight into the regulation of the desolvation process for high performance aqueous energy storage systems.

Investigation of thermochemical energy storage materials for building heating applications: Desorption behaviors of MgSO4·7H2O–silica gel composite

MgSO4-silica gel composites have a large potential for application in large-scale long-term energy storage systems, but the theoretical research on materials is not yet sufficiently thorough, and the reaction mechanism is still unclear, especially the lack of relevant experimental investigation and validation. Therefore, in order to better understand the nature and behavior of the desorption process, the reaction mechanism of monomer MgSO4·7H2O and MgSO4·7H2O-silica gel composites were investigated in this paper. The experimental results presented the desorption process of both the pure salt and the composites can be divided into six stages, and at 150 °C, the two can desorb 40.42 %–44.14 %, accounting for 79 %–86 % of the total desorption, so it is more appropriate to take 150 °C as the temperature of desorption in the energy storage system. The desorption mechanisms of pure salt and composite materials can be described by the same model in the same temperature range, and the desorption curve types and reaction mechanism models corresponding to different desorption temperatures were obtained, which were S-shape-A2 (110 °C and 120 °C), accelerated-R2 (130 °C), and decelerated-F1 (140 °C and 150 °C), respectively, which revealed the kinetics and control mechanisms of desorption process. The control mechanism, which was an important guideline for optimizing the heat and mass transfer process inside the salt particles. Compared with the pure salt, the activation energy and pre-exponential factor of the composites were lower, 48.55 kJ/mol (58.05 kJ/mol for the pure salt) and 3.31 × 104 s−1 (1.88 × 105 s−1 for the pure salt), respectively, indicating the number of active sites in the composites was higher and the reaction rate was faster; The lower the activation energy, the smaller the effect of temperature on the reaction rate constant. It can be seen the composite material is more advantageous in the process of practical application. After 60 cycles, the decay rate of adsorption/desorption performance of SM20 was only 5 %-8 %, indicating that the composite material had good cycling stability and can be used as a candidate material for large-scale long-term seasonal energy storage.