Grid-scale Energy Storage Systems Research Articles

(Invited) Redox Flow Batteries – Exploring Electrolyte Additives and Hybrid Organic/Inorganic Redox Pairs

Renewable energy sources are intermittent and thus require provision to store the energy when available using energy storage devices. These energy storage devices should be safe, efficient, and have a long life cycle for use in grid-scale energy storage systems. Lead-acid, Li-ion, and Redox Flow Batteries (RFBs) are examples of such energy storage devices. Among these energy storage systems, RFBs have unique advantages that make them attractive for large-scale energy storage applications, like a high cycle life of about 10,000 cycles.[1] The current generation of commercial RFBs use vanadium solution in different oxidation states as electrolytes (anolyte and catholyte), carbon-based electrodes and Nafion as the ion-exchange membrane. High cost, risk of electrolyte crossover, low volumetric energy density, and pumping losses limit the vanadium redox flow batteries (VRFBs).[2] Also, the Nafion membrane accounts for about 40% of the system's total cost.[3] To ensure high cycle life, the electrolytes must be stable (active material must remain dissolved in the supporting electrolyte), and vanadium ions should not crossover the Nafion membrane. The VRFBs tend to lose vanadium from electrolyte solutions due to the precipitation of V2O5 during charging, resulting in a significant loss of energy density. Additives help in maintaining the long-term stability of vanadium electrolytes. In this work, we have monitored the solubility and electrochemical characteristics of vanadium electrolyte solutions with V2O5 in the presence of different additives, namely HCl and MSA (methanesulfonic acid), for over three months.[4] The findings of this study provide insight into using these additives for VRFBs. Further research in RFBs has recently shifted towards redox-active aqueous-organic-based electrolytes consisting of Earth-abundant elements (C, H, O, N, S), accommodating the need for green, safe, and low-cost energy storage. We have studied the feasibility of using quinone-based organic electrolytes for RFBs. A proof-of-concept membrane-free two-compartment cell with an auxiliary electrode in each compartment was also demonstrated. In the conventional design, the hydrogen ions move through the Nafion membrane to balance charges but in the auxiliary electrode-based membrane-free setup, the auxiliary electrode in each compartment undergoes redox reactions opposite to the primary electrodes to balance charges.[5]References[1] Y.E. Durmus, H. Zhang, F. Baakes, G. Desmaizieres, H. Hayun, L. Yang, M. Kolek, V. Küpers, J. Janek, D. Mandler, S. Passerini, Y. Ein‐Eli, Side by Side Battery Technologies with Lithium‐Ion Based Batteries, Adv. Energy Mater. 10 (2020). https://doi.org/10.1002/aenm.202000089.[2] B. Turker, S. Arroyo Klein, E.M. Hammer, B. Lenz, L. Komsiyska, Modeling a vanadium redox flow battery system for large scale applications, Energy Convers. Manag. 66 (2013) 26–32. https://doi.org/10.1016/j.enconman.2012.09.009.[3] J. Ye, D. Yuan, M. Ding, Y. Long, T. Long, L. Sun, C. Jia, A cost-effective nafion/lignin composite membrane with low vanadium ion permeation for high performance vanadium redox flow battery, J. Power Sources. 482 (2021) 229023. https://doi.org/10.1016/j.jpowsour.2020.229023.[4] O.H. Nguyen, P. Iyapazham Vaigunda Suba, M. Shoaib, V. Thangadurai, Investigating the Electro-Kinetics and Long-Term Solubility of Vanadium Electrolyte in the Presence of Inorganic Additives, J. Electrochem. Soc. 170 (2023) 110523. https://doi.org/10.1149/1945-7111/ad0a75.[5] S.V. Venkatesan, K. Karan, S.R. Larter, V. Thangadurai, An auxiliary electrode mediated membrane-free redox electrochemical cell for energy storage, Sustain. Energy Fuels. 4 (2020) 2149–2152. https://doi.org/10.1039/c9se00734b.

High-Entropy Strategy to Suppress Volumetric Strain and Enhance Diffusion Rate of Na3V2(PO4)2F3 Cathode for Durable and High-Areal-Capacity Zinc-Ion Battery Pouch Cells

The burgeoning global environmental awareness and the escalating demand for renewable energy storage have intensified the critical need for next-generation battery technologies.1,2 In recent decades, there has been a sustained pursuit of grid-scale energy storage systems that balance practicality and efficiency. In this context, aqueous zinc-ion batteries (AZIBs) have emerged as a promising contender, driven by the distinct advantages of the 2.8-fold higher volumetric capacity (5849 mAh cm-3) of zinc metal over lithium metal (2062 mAh cm-3), and the use of non-toxic, cost-effective aqueous electrolyte. To date, substantial efforts have been dedicated to investigating suitable AZIB cathode materials, including Prussian blue analogs (PBAs), transition-metal (TM) oxides (e.g., MnO2 and V2O5), organic compounds, and polyanion-type compounds.Recently, there has been a notable surge of interest in polyanion-type compounds. Na3V2(PO4)2F3 (NVPF), demonstrates an operating potential of exceeding 1.60 V and an enhanced energy density of 97.5 Wh kg-1. Regrettably, these advantages are often counterbalanced by undesirable side reactions and sluggish ion kinetics, culminating in incompetent rate capabilities and suboptimal cycling stability.3 High-entropy (HE) materials have emerged as promising candidates for facilitating ion transport and fortifying cathode stability across various energy storage systems due to their exceptional design flexibility and compositional tunability.4,5 Inspired by conventional HE stabilization strategies, this work introduces a carbon-coated Na3V1.9(AlZnMnCrNb)0.1(PO4)2F3 cathode, denoted as HE-NVPF@C. Employing this cathode, coupled with a carbon-film-functionalized Zn anode, referred to as Zn@CF, and acetonitrile(AN)-water hybrid electrolyte, we configured an AZIB with substantial enhancements in long-term cycling stability and high areal capacity. AZIBs based on HE-NVPF@C cathodes presented a high reversible capacity of 77.45 mAh g−1 at 2C and remarkable cycling stability with a capacity loss of a mere 0.0031% per cycle over 6,000 cycles at 20C. In particular, the areal capacity of the HE-NVPF@C cathode reached up to 2.17 mAh cm-2, and HE-NVPF@C also attained a high capacity density of 78.2 mAh g-1 and 61.6 mAh g-1 when working under 50 and -20°C, making it more competitive among the reported cathodes in AZIBs. In addition, the pouch cell provides a long cycling lifespan with 90.8% capacity retention at 5C after 200 cycles. More importantly, the Zn2+ storage mechanism of the high-entropy NASICON-type cathode was systematically studied for the first time. In-situ X-ray diffraction (XRD) and density functional theory (DFT) calculations revealed that NVPF@C with high-entropy doping improved cycling stability due to the mitigated Jahn-Teller distortion, enhanced Zn2+ diffusion rate, and reduced lattice volumetric strain upon Zn2+ extraction and insertion. This work not only lays the door for developing stable AZIBs but also enriches the mechanistic discussion about the improved cycling or structural stability of high-entropy NASICON structures.Keywords: Zinc-ion battery; High-entropy material; NASICON; Na3V2(PO4)2F3; Pouch cellReference1 Cao, Y. et al. Bridging the academic and industrial metrics for next-generation practical batteries. Nat. nanotechnol. 14, 200-207, (2019).2 Xue, M. et al. Carbon-assisted anodes and cathodes for zinc ion batteries: From basic science to specific applications, opportunities and challenges. Energy Storage Mater. 62, 102940, (2023).3 Zhu, L. et al. A comprehensive review on the fabrication, modification and applications of Na3V2(PO4)2F3 cathodes. J. Mater. Chem. A 8, 21387-21407, (2020).4 Zeng, Y. et al. High-entropy mechanism to boost ionic conductivity. Science 378, 1320-1324, (2022).5 Yang, C. et al. All-temperature zinc batteries with high-entropy aqueous electrolyte. Nat. Sustain. 6, 325-335, (2023).

Grid variability and value assessment of long-duration energy storage under rising photovoltaic penetration: Evidence from Japan

Using high-resolution grid power balance and market data, this work investigates the effects of rising solar photovoltaic generation on the variability of large-scale net grid load and spot prices, and conducts an analysis of the potential balancing profits of various grid-scale energy storage systems. Analysis results show the correlation between PV (photovoltaic) generation and electricity demand has been identified as a significant factor influencing spot price value. As PV penetration increases, the value of spot prices experiences a notable decline, with values declining to nearly zero when the share of hourly PV generation surpasses 70 %. The volatility of electricity spot prices has a substantial impact on utilization rates and economic profits of energy storage systems employed for grid energy balancing. Despite the lower roundtrip efficiency, reversible hydrogen storage system can offer positive benefits. The longer storage duration offers the advantage of capturing greater dispatch profits by exploiting price differences over extended periods. Considering the time-varying nature of spot prices, the rated power capacity of the storage system plays a significant role in determining its utilization rates. The larger rated charging and discharging ability of the storage system allows for more effective utilization of price fluctuations, resulting in greater profitability.

A bifunctional electrocatalytic graphite felt for stable aqueous zinc-polyiodide flow batteries

The appealing features of high safety, environmental friendliness, and flexible layout make the Zn–I2 flow batteries attractive for implementation in long-duration grid-scale energy storage systems. However, the uncontrollable self-transformation of high-soluble polyiodide species often result in the limited reutilization of I3−/I− redox couple and compromise its theoretical energetic potentials. Herein, FeP nanoclusters embedded in N and P co-dopped carbon layer render the functional graphite felt with strong interaction between polyiodides and substrate in combination with the accelerated I−/I3− redox kinetics under working conditions. The heteroatoms and nanoclusters served synergically as strong chemisorption and electrocatalytic hotspots for iodine and its intermediates conversion. The strong interactions between polar matrix and active species facilitated interfacial physicochemical confinement effect mitigates polyiodide crossover and the electrocatalysis effect promises efficient iodine conversion and stable cycling performance. Consequently, the Zn–I2 flow battery delivers excellent rate performance, ultralong cycling life for 1000 cycles with a recorded average Coulombic efficiency of 98.1 %, and substantially enhanced anti-self-discharge capability. The rational modification of carbon felt represents a promising direction to unlock the practical potentials of Zn–I2 flow chemistry.

Surface Modification Induces Oriented Zn(002) Deposition for Highly Stable Zinc Anode

Aqueous zinc metal batteries (AZMBs) are considered a promising candidate for grid-scale energy storage systems owing to their high capacity, high safety and low cost. However, Zn anodes suffer from notorious dendrite growth and undesirable surface corrosion, severely hindering the commercialization of AZMBs. Herein, a strategy for engineering a dense ZnO coating layer on Zn anodes using the atomic layer deposition (ALD) technique is developed, aiming to improve its long-term cycling stability with fewer Zn dendrites. The surface-modified Zn anode (ZnO@Zn) exhibits an excellent long-cycling life (680 h) and stable coulombic efficiency when being used in a symmetric cell. Moreover, the ZnO@Zn electrode shows a high stability with almost no capacity decay after 1100 cycles at 2C in a full cell using MnO2 as the cathode. The ZnO coating is conducive to reducing corrosion and the generation of by-products, thus increasing the reversibility of Zn2+/Zn stripping/plating. Particularly, density functional theory (DFT) calculation results reveal that the ZnO coating layer could effectively lower the adsorption energy of the Zn(002) plane in ZnO@Zn, inducing the preferential deposition of Zn2+ towards the (002) crystal plane with fewer Zn dendrites. The surface ZnO coating protocol provides a promising approach to achieve a dendrite-free Zn anode for stable AZMBs.

Maltodextrin as a Commercial-Grade Electrolyte Additive Against Dendrite Formation and Side Reactions for Aqueous Zinc-Ion Batteries.

Aqueous zinc-ion batteries (AZIBs) directly using zinc metal anodes are promising candidates for grid-scale energy storage systems due to their intrinsic high theoretical capacity, high safety, and environmental friendliness. However, the uncontrolled dendrite growth and water-triggered side reactions seriously plague its practical application. Herein, a cost-effective and green additive, maltodextrin (MD) is presented, to simultaneously guide the smooth Zn deposition and inhibit the occurrence of water-related side reactions. Combing experimental characterizations and theoretical calculations shows that the MD molecules could reconstruct the Helmholtz plane, induces a preferential growth of zinc along the (002) plane, and the optimized regulation of the Zn2+ diffusion path and deposition location also results in the formation of fine-grained Zn deposition layers, thereby inhibiting dendrite growth. In addition, MD molecules readily adsorb to the zinc anode surface, which isolates water molecules from direct contact with the zinc metal, reducing hydrogen precipitation reactions and inhibiting the formation of by-products. Consequently, the Zn||Zn symmetric cell with MD achieves ultra-long stable cycles of up to 5430h at 1mA cm-2 and 1mA h cm-2, and the Cu||Zn asymmetric cell can stable cycle 1000 cycles with an average coulomb efficiency of 99.78%.

A multifunctional desalination-osmotic energy storage (DOES) system for managing energy and water supply

Net-zero carbon emission target for mitigating climate change accelerates the exploitation of renewable energy, such as solar and wind, as power origin in utilities sector. However, the intermittency of renewable energy escalates the supply-demand mismatch in not only electricity sector but also water sector, as freshwater supply increasingly relies on unconventional, energy-intensive desalination that is increasingly powered by renewables. To enhance the energy-water resilience, we propose a desalination-osmotic energy storage (DOES) system, which alternates the operation of reverse osmosis (RO) for desalination and pressure retarded osmosis (PRO) for electricity generation, achieving multiple functions including freshwater production and storage, grid energy storage, and eventually bulk-scale management of freshwater and energy supply. Via innovative system design and operation integrating semi-closed (SC) and closed-circuit (CC) configurations in RO and PRO modes in the proposed DOES, energy loss arising from over-pressurization in RO and under-pressurization in PRO could be substantially reduced. As a result, DOES can achieve practical maximum energy efficiencies of >75 % for both RO desalination and PRO electricity generation, and a round-trip efficiency of >68 % when used as a grid-scale energy storage system (ESS). Apart from the quantitative analysis of energy performance, a qualitative comparison of various other performance metrics between DOES and other grid ESSs is also conducted. Given its various performance advantages as well as multi-functionality, the DOES system could be an important complement to, though not replacement of, existing grid-scale ESSs.

Recent Progress in Developing High-Performance Anode Materials for Next-Generation Sodium-Ion Batteries

Rechargeable lithium-ion batteries (LIBs) have attracted great attention due to their large-scale energy storage applications such as electric vehicles (EVs) and grid-scale energy storage systems (ESSs). The ongoing transition towards EVs has accelerated ever-increasing demand for LIBs that causes the shortage of lithium metal resources and their expensive price. Therefore, great efforts have been made to exploit an alternative system that replaces the conventional LIBs. While sodium-ion batteries (SIBs) can be the most evident alternatives to LIBs based on the natural abundance and low cost of sodium resources, the major scientific challenges reside in developing the new anode materials due to the poor performance of conventional LIB anodes in Na cells, such as graphite and silicon. This article reviews the potential of SIBs as promising alternatives to LIBs and recent progress in developing high-performance anode materials for SIBs. The strengths and drawbacks of recently developed anode materials have been discussed, including graphite, hard carbon, silicon, phosphorus, and other transition metal compounds such as oxides, phosphides, and sulfides.

Zinc ion Batteries: Bridging the Gap from Academia to Industry for Grid-Scale Energy Storage.

Zinc ion batteries (ZIBs) exhibit significant promise in the next generation of grid-scale energy storage systems owing to their safety, relatively high volumetric energy density, and low production cost. Despite substantial advancements in ZIBs, a comprehensive evaluation of critical parameters impacting their practical energy density (Epractical) and calendar life is lacking. Hence, we suggest using formulation-based study as a scientific tool to accurately calculate the cell-level energy density and predict the cycling life of ZIBs. By combining all key battery parameters, such as the capacity ratio of negative to positive electrode (N/P), into one formula, we assess their impact on Epractical. When all parameters are optimized, we urge to achieve the theoretical capacity for a high Epractical. Furthermore, we propose a formulation that correlates the N/P and Coulombic efficiency of ZIBs for predicting their calendar life. Finally, we offer a comprehensive overview of current advancements in ZIBs, covering cathode and anode, along with practical evaluations. This Minireview outlines specific goals, suggests future research directions, and sketches prospects for designing efficient and high-performing ZIBs. It aims at bridging the gap from academia to industry for grid-scale energy storage.

Binder-free Cu1.9Bi0.1Se@SWCNT hybrid anodes for lithium-ion and sodium-ion batteries

The rapid growth of portable electronic devices, electric vehicles, and grid-scale energy storage systems has accelerated the demand for enhancing existing materials and innovating new materials in rechargeable battery technologies. Li-ion batteries have dominated the energy storage field among the various battery systems. Na-ion batteries have emerged as promising candidates due to their similarities to Li-ion battery chemistry, low cost, and environmental sustainability. This study explores the potential advantages of synthesizing the binder-free Cu1.9Bi0.1Se@SWCNT heterostructure directly on the copper collector surface. A crucial aspect of this research is the intentional use of nanostructuring during synthesis. This technique capitalizes on the benefits of greater surface area, enhanced electron transport, and superior ionic conductivity. The synthesis method not only ensures excellent electrical and mechanical contact with the collector but also omits the need for a binder, offering a potential for improved overall performance in Li-ion and Na-ion batteries. The electrodes were synthesized using a simple and cost-effective physical vapor deposition method. The structural, morphological, and electrochemical properties of the electrodes were characterized. The binder-free Cu1.9Bi0.1Se@SWCNT electrode with 25 % SWCNT content exhibits excellent performance in Li-ion half cells, maintaining a high energy capacity of 556 mAh g−1 at 0.1 A g−1 over 100 cycles and 244 mAh g−1 at 0.5 A g−1 over 750 cycles. However, in the Na-ion battery system, the performance is notably poorer, revealing challenges and limitations. Most likely, the larger size of sodium ions posed difficulties in intercalation within the anode material structure.

Recent Advances in Electrospun Nanostructured Electrodes in Zinc-Ion Batteries

Zinc-ion batteries (ZIBs) are increasingly recognized as highly promising candidates for grid-scale energy storage systems due to their cost-effectiveness, environmental friendliness, and high security. Despite recent advancements in the research of cathode materials, Zn anodes, and electrolytes, several challenges persist and must be addressed, including cathode dissolution, generation of by-products, and zinc dendrite formation, which hinder the future application of ZIBs. In this review, we systematically summarize the recent developments in electrospinning technology within ZIBs. First, the principle technical parameters and subsequent thermal treatment of electrospinning technology are discussed, and then the synthetic preparation, morphologies, and electrochemical performance of electrospun nanostructured electrodes in ZIBs are comprehensively reviewed. Finally, some perspectives on research directions and optimization strategies for electrospinning technology in energy applications are outlined.

A preferentially adsorbed layer on the Zn surface manipulating ion distribution for stable Zn metal anodes

A bifunctional electrolyte additive enabling stable Zn metal anodes.

Early prediction of battery degradation in grid-scale battery energy storage system using extreme gradient boosting algorithm

The growth of battery energy storage systems (BESS) is caused by the variability and intermittent nature of high demand and renewable power generation at the network scale. In the context of BESS, Lithium-ion (Li-ion) battery occupies a crucial position, although it is faced with challenges related to performance battery degradation over time due to electrochemical processes. This battery degradation is a crucial factor to account for, based on its potential to diminish the efficiency and safety of electrical system equipment, thereby contributing to increased system planning costs. This implies that the health of battery needs to be diagnosed, particularly by determining remaining useful life (RUL), to avoid unexpected operational costs and ensure system safety. Therefore, this study aimed to use machine learning models, specifically extreme gradient boosting (XGBoost) algorithm, to estimate RUL, with a focus on the temperature variable, an aspect that had been previously underemphasized. Utilizing XGBoost model, along with fine-tuning its hyperparameters, proved to be a more accurate and efficient method for predicting RUL. The evaluation of the model yielded promising outcomes, with a root mean square error (RMSE) of 90.1 and a mean absolute percentage error (MAPE) of 7.5 %. Additionally, the results showed that the model could improve RUL predictions for batteries within BESS. This study significantly contributed to optimizing planning and operations for BESS, as well as developing more efficient and effective maintenance strategies.

The Role of Energy Density for Grid-Scale Batteries

For grid-scale battery energy storage systems it is often presumed that cell level energy density is not too important. Yet, countless publications highlight low energy density as the key limitation of technologies such as redox flow batteries or aqueous alkali-ion batteries that are inherently developed for stationary applications.Here, we resolve this apparent conflict by quantifying the areal energy density, expressed in kWh m-2, of over forty MWh-scale battery energy storage systems deployed around the world.[1] Via satellite imagery we compare lithium-ion, sodium-sulfur, and flow battery projects and show that the amount of energy that is stored per land area is often comparable between these technologies, even though the energy density on cell level varies by an order of magnitude. We highlight excellent safety and vertical scalability as key untapped advantages of aqueous batteries and provide examples of where they can excel, besides simply competing with state-of-the-art lithium-ion batteries. We show, for example, that MWh-scale aqueous flow batteries can safely be deployed underground and within buildings, feats that due to safety constraints are not possible with current lithium-ion batteries at this scale.Seeing satellite images of battery installations near solar farms is a humbling experience that every researcher working in the field should come across and we provide the locations of all the examined battery installations in a Google Earth file. Grasping the fantastical scale at which renewables are, and must continue to be, deployed certainly provides some perspective regarding energy density of individual battery cells. [1] Reber, D., Jarvis, S.R., Marshak, M.P., The role of energy density for grid-scale batteries, ChemRxiv, 2022, doi: 10.26434/chemrxiv-2022-5ddhs

Development of Electro-Thermal Model for Air Cooling Study of Electric Vehicle Lithium-Ion Battery Module Operating in Indian Conditions and Drive Cycle

Lithium-ion cells have higher energy density at a specific power, making them a primary choice for battery packs in energy storage of modern technology, powering from smartphones to Electric vehicle (EV) and grid-scale energy storage systems. However, their performance, safety and lifespan are temperature sensitive and developing a fail-safe mechanism is considered as a pressing priority. In the present study, a 2D electro-thermal model is developed in MATLAB to characterize the thermal behaviour of cylindrical cells (individual and inline) during discharge. The thermal model solves the transient heat conduction equation with internal heat generation. The model is validated with the available experimental data for a single cell at a constant discharge rate and found to be in good agreement within 0.5°C. The analysis is extended to a battery module with 6 cell-inline configuration and validated. This validated model is used to study the impact of multiple cells (1-10) in inline configuration. For Indian drive cycle analysis, the current profile is estimated based on the drive cycle and its impacts on cell temperature rise in battery module is studied when subjected to variation in monthly average ambient temperature. Battery module maximum temperature rises to 60 °C and Δ T (Tmax - Tmin) across cells is 8.8 °C during summer conditions under natural convection due to multiple drive cycle loading. The battery module temperature can be kept under safe operating limits (Tmax≤ 45 °C, Δ T ≤ 4 °C) with forced convection of 2 m/s and 25 °C. The study aims to provide insights into the thermal behaviour of Lithium-ion cells that can be used to design safe and cost-effective air-cooled thermal management system for battery module.

Sustainable Dual-Ion Batteries beyond Li.

The limitations of resources used in current Li-ion batteries may hinder their widespread use in grid-scale energy storage systems, prompting the search for low-cost and resource-abundant alternatives. "Beyond-Li cation" batteries have emerged as promising contenders; however, they confront noteworthy challenges due to the scarcity of suitable host materials for these cations. In contrast, anions, the other crucial component in electrolytes, demonstrate reversible intercalation capacity in specific materials like graphite. The convergence of anion and cation storage has given rise to a new battery technology known as dual-ion batteries (DIBs). This comprehensive review presents the current status, advancements, and future prospects of sustainable DIBs beyond Li. Notably, most DIBs exhibit similar cathode reaction mechanisms involving anion intercalation, while the distinguishing factor lies in the cation types functioning at the anode. Accordingly, the review is organized into sections by various cation types, including Na-, K-, Mg-, Zn-, Ca-, Al-, NH4 + -, and proton-based DIBs. Moreover, a perspective on these novel DIBs is presented, along with proposed protocols for investigating DIBs and promising future research directions. It is envisioned that this review will inspire fresh concepts, ideas, and research directions, while raising important questions to further tailor and understand sustainable DIBs, ultimately facilitating their practical realization.

Scalable fabrication of free-standing and integrated electrodes with commercial level of areal capacity for aqueous zinc-ion batteries

Aqueous zinc-ion batteries (AZIBs) present a highly promising avenue for the deployment of grid-scale energy storage systems. However, the electrodes fabricated through conventional methodologies not only suffer from insufficient mass loadings, but also are susceptible to exfoliation under deformations. Herein, a scalable and cost-effective freezing-thawing method is developed to construct free-standing and integrated electrode, comprising H11Al2V6O23.2, carboxymethyl cellulose, and carbon nanotubes. Benefiting from the synergistic effect of these components, the resultant electrode exhibits superior flexibility and robustness, large tensile strength, exceptional electrical conductivity, and favorable electrolyte wettability. Under a large mass loading of 8 mg cm−2 (corresponding to a negative/positive electrode capacity ratio of 2.09), the electrode achieves remarkable capacity of 345.2 mAh/g (2.76 mAh cm−2) at 0.2 A/g and maintains 235.2 mAh/g (1.88 mAh cm−2) at 4 A/g, while sustaining an impressive capacity retention of 97.7 % over 5000 cycles. These considerably outperform conventional electrodes employing traditional binders. Even at an elevated mass loading of 14 mg cm−2 or when operated at a low temperature of − 30 °C, the electrode continues to deliver excellent electrochemical performance (e.g., extraordinary areal capacity of 4.32 mAh cm−2). In addition, the electrode owns outstanding tolerance to external forces. This research contributes to our understanding of the pivotal challenges within the realm of AZIB technology.

Battery Earth: using the subsurface at Boulby underground laboratory to investigate energy storage technologies

Renewable energy provides a low-carbon alternative to power generation in the UK. However, the resultant supply varies on daily, weekly and seasonal cycles, such that for green energies to be fully exploited new grid-scale energy storage systems must be implemented. Two pilot facilities in Germany and the United States have demonstrated the potential of the Earth as a battery to store compressed air, using off-peak surplus energy. Natural accumulations of salt (halite deposits) in the UK represent a large and untapped natural storage reservoir for compressed air with the ability to provide instantaneous green energy to meet peak demand. To realise the potential of this emerging technology, a detailed knowledge of the relationship between mechanics, chemistry and geological properties is required to optimise cavern design, storage potential and economic feasibility. The variable stresses imposed on the rock matrix by gas storage, combined with the cyclic nature of cavern pressurisation are barriers to deployment that need to be addressed to enable large-scale adoption of schemes. Well-designed field experiments are a lynchpin for advancing research in this area, especially when supported by state-of-the-art characterisation and modelling techniques. The research facility at STFC’s Boulby Underground Laboratory presents the ideal location to tackle these fundamental issues to optimise “Battery Earth”.

Spherical Shell with CNTs Network Structuring Fe-Based Alluaudite Na2+2 δ Fe2- δ (SO4 )3 Cathode and Novel Phase Transition Mechanism for Sodium-Ion Battery.

Iron-based sulfate cathodes of alluaudite Na2+2 δ Fe2- δ (SO4 )3 (NFS) in sodium-ion batteries with low cost, steady cycling performance, and high voltage are promising for grid-scale energy storage systems. However, the poor electronic conductivity and the limited understanding of the phase-evolution of precursors hinder obtaining high-rate capacity and the pure phase. Distinctive NFS@C@n%CNTs (n = 1, 2, 5, 10) sphere-shell conductive networks composite cathode materials are constructed creatively, which exhibit superior reversible capacity and rate performance. In detail, the designed NFS@C@2%CNTs cathode delivers an initial discharge capacity of 95.9 mAh g-1 at 0.05 C and up to 60 mAh g-1 at a high rate of 10 C. The full NFS@C@2%CNTs//HC cell delivers a practical operating voltage of 3.5V and mass-energy density of 140Wh kg-1 at 0.1 C, and it can also retain 67.37 mAh g-1 with a capacity retention rate of 96.4% after 200 cycles at 2 C. On the other hand, a novel combination reaction mechanism is first revealed for forming NFS from the mixtures of Na2 Fe(SO4 )2 ·nH2 O (n = 2, 4) and FeSO4 ·H2 O during the sintering process. The inspiring results would provide a novel perspective to synthesize high-performance alluaudite sulfate and analogs by aqueous methods.

Large-scale energy storage system: safety and risk assessment

The International Renewable Energy Agency predicts that with current national policies, targets and energy plans, global renewable energy shares are expected to reach 36% and 3400 GWh of stationary energy storage by 2050. However, IRENA Energy Transformation Scenario forecasts that these targets should be at 61% and 9000 GWh to achieve net zero carbon emissions by 2050 and limit the global temperature rise within the twenty-first century to under 2 °C. Despite widely known hazards and safety design of grid-scale battery energy storage systems, there is a lack of established risk management schemes and models as compared to the chemical, aviation, nuclear and the petroleum industry. Incidents of battery storage facility fires and explosions are reported every year since 2018, resulting in human injuries, and millions of US dollars in loss of asset and operation. Traditional risk assessment practices such as ETA, FTA, FMEA, HAZOP and STPA are becoming inadequate for accident prevention and mitigation of complex energy power systems. This work describes an improved risk assessment approach for analyzing safety designs in the battery energy storage system incorporated in large-scale solar to improve accident prevention and mitigation, via incorporating probabilistic event tree and systems theoretic analysis. The causal factors and mitigation measures are presented. The risk assessment framework presented is expected to benefit the Energy Commission and Sustainable Energy Development Authority, and Department of Standards in determining safety engineering guidelines and protocols for future large-scale renewable energy projects. Stakeholders and Utility companies will benefit from improved safety and reliability by avoiding high-cost asset damages and downtimes due to accident events.