Large-scale Battery Energy Storage Research Articles

(Invited) Accelerating Material Design for Aqueous Organic Redox Flow Batteries

Aqueous soluble organic (ASO) redox-active materials have recently shown great promise as alternatives to transition metal ions to be employed as energy-bearing active materials in redox flow batteries for large-scale energy storage because of their structural tunability, cost-effectiveness, availability, and safety features. Development so far however has been limited to a small palette of organics that are aqueous soluble. How to quickly identify and design organic molecules for the targeted properties became a critical challenge in accelerating the aqueous organic flow battery development.In this presentation, a data-driven material design process is discussed. This process incorporates database building, machine learning modeling for properties prediction, and the subsequent material synthesis and testing. Examples including Fluorenone and Phenizane derivative development for the flow battery application will be discussed.Reference: Feng et al., Science 372, 836–840 (2021)

Current trajectory coefficient based time domain line protection for battery storage energy stations

On account of distinctive fault signatures, the extensive integration of large-scale battery energy storage stations (BESSs) results in severe performance degradation of relaying protection. Firstly, the performance problems of classic current differential protection and recently proposed cosine similarity coefficient-based pilot protection are illustrated. Subsequently, the trajectories of two current pairs in two-dimensional space, i.e., fault path current and current on BESS-side, fault path current and current on grid-side, are described and relationship of these three currents is analyzed. On this basis, this paper presents current trajectory coefficient-based time domain protection algorithm for transmission lines connecting BESSs. It describes the basic principle of protection algorithm and designs the operating and restraining regions of two current trajectories. The authors widely assessed the performance of proposed protection algorithm under internal fault by varying fault location, type, resistance and operating state of BESS. Furthermore, the security of proposed protection algorithm was also tested under various nonideal conditions, including severe current transformer (CT) saturation, CT measurement error and outliers. The results indicate that proposed protection algorithm offers gratifying performance in operating speed, dependability, security and selectivity, and outperforms current differential protection and recently proposed pilot protection.

Pillaring of a conductive polymer in layered V2O5 boosting ultra-fast Zn2+/H+ storage in aqueous media

Aqueous secondary zinc-ion batteries are promising candidates to replace lithium-ion batteries for large-scale energy storage, due to their high safety and low cost. However, the developed cathodes materials are facing low capacity or low cycle life due to sluggish diffusion kinetics. Therefore, the design of a cathode with ultrafast ion diffusion kinetics remains a great challenge. Here, we propose an in-situ intercalation strategy of polypyrrole to improve the cation diffusion kinetics of V2O5. The polypyrrole as a guest significantly enlarges the interlayer spacing, paving the ‘‘superhighway’’ for cation diffusion. In addition, thanks to the unique π-conjugated structure, polypyrrole can shield the electrostatic force of Zn2+ and the host oxygen-sublattice. The energy storage mechanism of the cathode was shown to be a stepwise H+/Zn2+co-intercalation by means of galvanostatic intermittent titration technique (GITT), electrochemical impedance spectroscopy (EIS) and ex situ X-ray diffraction (XRD). Based on the above advantages, the polypyrrole-intercalated V2O5 demonstrates high capacities and excellent cycling performance (220 mA h g−1 after 2000 cycles at 10 A g−1).

A simple and effective methodology for sizing electrical energy storage (EES) systems based on energy balance

The use of the electrical energy storage (EES) plays an important role in the transition of energy generation towards renewable energy sources (RESs). An effective sizing of EES systems is very important in order to cope with the volatility of RESs and to ensure a reliable energy supply. The present paper provides a methodology which helps to determine the minimum required EES size for conceiving a fully standalone system. Its approach is based on the evaluation of the energy balance for a given design period, and it can also be applied for sizing the EES system in grid-connected applications. The methodology was validated using measurement data obtained from two different systems corresponding to: a) a near-zero energy building with local generation sources, and b) a large-scale battery energy storage system (BESS) installed in a factory and used for peak-shaving. The obtained results confirmed the effectiveness of the proposed methodology by estimating the required size of the EES system. A good correlation was found between the estimated and the installed BESS size in the considered systems. The deviation between real and estimated BESS capacities was found to be less than 5%.

Origin of Air-Stability for Transition Metal Oxide Cathodes in Sodium-Ion Batteries.

The air-sensitivity of transition metal oxide cathode materials (NaxTMO2, TM: transition metal) is a challenge for their practical application in sodium-ion batteries for large-scale energy storage. However, the deterioration mechanism of NaxTMO2 under ambient air is unclear, which hinders the precise design of air-stable NaxTMO2. Here, we revealed the origin of NaxTMO2 degradation by capturing the initial degradation status and microstructural evolution under ambient atmospheres with optimal humidity. It was found that the insertion of CO2 into Na layers along (003) planes of NaxTMO2 led to initial growth of Na2CO3 nanoseeds between TM layers, which initiated fast structure degradation with surface cracks and extrusion of Na2CO3 out of NaxTMO2. The degradation extents and pathways for NaxTMO2 could be highly associated with crystal orientation, particle morphology, and ambient humidity. Interestingly, the deteriorated NaxTMO2 could be completely healed through optimal recalcination, showing even improved air-stability and electrochemical performance. This work provides a helpful perspective on the interfacical structure design of high-performance NaxTMO2 cathodes for sodium-ion batteries.

Consensus-based decision making approach for techno-economic operation of largescale battery energy storage in industrial microgrids

Utility-scale battery energy storage systems (BESSs) are emerging as an essential part of future power grids. A framework for the techno-economic application of a BESS in a dc coupled hybrid microgrid serving a mining industry is presented. Specifically, a multi-level consensus-based decision-making (MCD) approach is proposed for the energy management of the microgrid and the active/reactive power control of the microgrid's converters. The MCD can promote the operation of microgrids in the national electricity market as an economic unit. Also, the heterogeneous power curve of mining machines, the intermittency of renewables and the uncertainties of power systems can be addressed with reduced complexity. Whilst, the utility grid can apply and lead the regulatory parameters for the power system, as well as the microgrid, in accordance with the generator performance standards (GPS). A detailed electromagnetic transients (EMT) model is developed in PSCAD for a realistic test system and the effectiveness of the proposed MCD is pervasively assessed through different case studies. According to the assessed scenarios, the operational cost of the microgrid is decreased and the highly varying power curve of the renewables and mining industry is flattened. Further, the operational conditions of the microgrid can be autonomously controlled to mitigate unpredicted voltage disturbances, which can support the stability of power systems.

Magnesium/Lithium Hybrid Batteries Based on SnS 2 -MoS 2 with Reversible Conversion Reactions

The magnesium/lithium hybrid batteries (MLHBs) featuring dendrite-less deposition with Mg anode and Li-storage cathode are a promising alternative to Li-ion batteries for large-scale energy storage. However, their limited energy density limits their practical implementation. To improve this, beyond the commonly proposed intercalation compounds, high-capacity conversion-type cathodes based on heterostructures of tin sulphide-molybdenum disulphide (SnS 2 -MoS 2 ) are proposed in this work. Individual SnS 2 is already a promising high-capacity electrode material for multivalent batteries and undergoes conversion reactions during the ion storage process. The introduction of S-deficient MoS 2 enhances the reversibility of SnS 2 in the conversion reaction via strong polysulfide anchoring and catalytic effect. Our results show that the SnS 2 -MoS 2 electrode achieves a high charge capacity of ~600 mAh g -1 at 50 mA g -1 and an excellent rate capability of 240 mAh g -1 at 1000 mAh g -1 with a negligible capacity fading rate of 0.063% per cycle across 1000 cycles. The results highlight a new direction toward designing 2D heterostructures as high-capacity cathodes beyond intercalation-type cathodes for multivalent-ion batteries.

Reliability Assessment of Renewable Power Systems Considering Thermally-Induced Incidents of Large-Scale Battery Energy Storage

The battery energy storage system (BESS) has been envisaged as an effective solution for renewable energy accommodation in power systems. However, the residual capacity and maximum power of large-scale BESS are highly affected by thermally-induced incidents such as battery degradation and Thermal Runaway (TR) propagation. In the prior-art studies, the impacts of thermally-induced incidents on the BESS service performance have not been well modeled, resulting in relatively over-optimistic reliability estimation of power systems. In this paper, the reliability of large-scale grid-connected BESSs as well as its impacts on the overall reliability of power systems are investigated considering the battery degradation and TR propagation. To quantify the time-varying performance of the BESS, a multi-state model is constructed. The proposed model describes the aging process of batteries inside the BESS, incorporating the combined effects of sequential TR and the performance degradation of the surrounding batteries due to heat absorption. Based on the Monte Carlo method, scenarios that reflect the uncertainties of the intermittent wind generation and fluctuating loads are simulated. An optimal scheduling model is deployed, and a solution algorithm is proposed to calculate the scheduling results of the BESS in the real-time performance range subject to its thermal conditions. Case studies are conducted to validate the effectiveness of the proposed model and technique.

Perspective on organic flow batteries for large-scale energy storage

The organic flow batteries have been considered as the promising systems for electrochemical energy storage because of their potential advantages in promoting energy density and lowering the cost of electrolytes. Enormous efforts have been devoted to design high-performance organic flow batteries, but fundamental and technological hurdles remain to be overcome. Herein, we summarize the current state of organic flow batteries in both aqueous and nonaqueous systems, discuss their limitations, and provide guidance for the further development of the organic flow battery.

Reversible Ketone Hydrogenation and Dehydrogenation for Aqueous Organic Redox Flow Batteries

Aqueous soluble organic (ASO) redox-active materials have recently shown great promise as alternatives to transition metal ions to be employed as energy-bearing active materials in redox flow batteries for large-scale energy storage because of their structural tunability, cost-effectiveness, availability, and safety features. Development so far however has been limited to a small palette of organics that are aqueous soluble and tend to display the necessary redox reversibility within the water stability window. There is however noticeably much larger number of organic molecules that exhibit some degree of irreversible redox activities. In this presentation, we show how the molecular engineering of fluorenone enables the alcohol electro-oxidation needed for reversible ketone hydrogenation and dehydrogenation at room temperature without the use of a catalyst. Flow batteries based on these fluorenone derivative anolytes operate efficiently and exhibit stable long-term cycling at ambient and mildly increased temperatures in a non-demanding environment. These results suggest the potential for identifying other atypical organic redox molecules for energy storage. Reference: Feng et al., Science 372, 836–840 (2021)

Suppressing the interlayer-gliding of layered P3-type K0.5Mn0.7Co0.2Fe0.1O2 cathode materials on electrochemical potassium-ion storage

In recent years, potassium-ion batteries (KIBs) have emerged as a promising alternative candidate to replace lithium-ion batteries for large-scale energy storage devices owing to the natural abundance of potassium and similar mechanism as lithium-ion batteries. In particular, transition metal oxide cathode materials have attracted growing attention due to their high theoretical capacities and low cost compared with other cathode materials. Nevertheless, due to the larger ionic radius of K-ions, transition metal oxide cathode materials suffer from irreversible structural evolution and interlayer-gliding of transition metal layers in potassiation/depotassiation, which results in sluggish kinetics and structural instability. This limited capacity and unsatisfactory cycling properties inhibit the practical application of potassium-ion batteries. It still remains a challenge to develop the suitable cathode materials for potassium-ion batteries. In this work, the interlayer-gliding and irreversible P3–O3 structure transition were suppressed via the replacement of cobalt and iron, and the doping mechanism was investigated by in situ x-ray diffraction. The incorporation of Co ions and Fe ions enlarges the d-space between the transition metal layers, reduces the resistance of K+ migration, and provides the buffer spaces to suppress the interlayer-gliding and P3–O3 phase transformation in electrochemical potassium-ion storage, leading to an enhanced rate capability (58 mA h g−1 at 1 A g−1) and superior cycling stability (71% after 300 cycles at 200 mA g−1). This strategy provides a better understanding for the effect of Co–Fe substitution in suppressing interlayer-gliding and improving electrochemical properties for the development of a novel cathode material for potassium-ion batteries.

Peak shaving benefit assessment considering the joint operation of nuclear and battery energy storage power stations: Hainan case study

The rapid development of battery energy storage technology provides a potential way to solve the grid stability problem caused by the large-scale construction of nuclear power. Based on the case of Hainan, this study analyses the economic feasibility for the joint operation of battery energy storage and nuclear power for peak shaving, and provides an effective solution framework for construction scale and battery type determination. Under the proposed framework, a novel cost model for the large-scale battery energy storage power station is proposed. Then, economic analysis is conducted to get the most economical battery type and construction scale by considering the comprehensive economic benefit of the joint operation under the limit of the load factor. On this basis, sensitivity analysis of economic indicators to control parameters and economic parameters is performed to further demonstrate the economic feasibility of the joint operation. Comparative analysis shows that 270 MW lithium iron phosphate battery energy storage power station has the best and stable comprehensive performance in terms of the IRR, PBP and LCOE, which are 16.27%, 6.27 year and 0.464¥/kWh, respectively. In comparison with the pumped storage, the battery energy storage has lower initial investment, faster capital recovery and smaller floor area under the joint operation mode. Moreover, sensitivity analysis illustrates that the large-scale application of battery energy storage still depends on the trade-off between the cost performance of battery and the real-time electricity price.

Lithium and Sodium Ion Binding Mechanisms and Diffusion Rates in Lignin-Based Hard Carbon Models.

Hard carbons are the primary candidate for the anode of next-generation sodium-ion batteries for large-scale energy storage, as they are sustainable and can possess high charge capacity and long cycle life. These properties along with diffusion rates and ion storage mechanisms are highly dependent on nanostructures. This work uses reactive molecular dynamics simulations to examine lithium and sodium ion storage mechanisms and diffusion in lignin-based hard carbon model systems with varying nanostructures. It was found that sodium will preferentially localize on the surface of curved graphene fragments, while lithium will preferentially bind to the hydrogen dense interfaces of crystalline and amorphous carbon domains. The ion storage mechanisms are explained through ion charge and energy distributions in coordination with snapshots of the simulated systems. It was also revealed that hard carbons with small crystalline volume fractions and moderately sized sheets of curved graphene will yield the highest sodium-ion diffusion rates at ∼10–7 cm2/s. Self-diffusion coefficients were determined by mean square displacement of ions in the models with extension through a confined random walk theory.

Enhancing long-term voltage stability of a power system integrated with large-scale photovoltaic plants using a battery energy storage control scheme

Due to distinct differences in dynamic characteristics of large-scale photovoltaic plants (LS-PVPs) compared to conventional generation units, utilities face some new non-traditional operational problems, more specifically in terms of voltage stability. This paper analyzes the impact of various control methods of LS-PVPs on long-term (LT) voltage stability. A new corrective voltage control (CVC) scheme is proposed for the large-scale battery energy storage system (LS-BESS) to prevent LT voltage instability in a power system integrated with LS-PVPs. For this purpose, a new coupling between optimization and dynamic simulations is proposed to treat the problem as an objective function, which uses the particle swarm optimization (PSO) algorithm. This objective function is used to minimize investment costs and voltage drops of the system by determining the optimal number, location, and capacity of LS-BESSs. Furthermore, the effects of local voltage control modes and power priority settings of LS-BESSs are investigated. Besides, effectiveness of the proposed approach is validated through several scenarios using time-domain simulations of a more realistic system, namely the Nordic system. According to the results, upon using the proposed approach, negative effects of LS-PVPs on voltage stability and costs required for expanding and reinforcing the transmission network decreased. In addition, voltage collapse was prevented, investment costs of LS-BESSs were minimized, and costs required for reactive power compensation devices and communication between controllers decreased.

Multifactor Effects on the Thermal Performances of Molten-Salt Solid-State Lithium-Ion Batteries: A Numerical Study

The molten-salt battery is a very suitable battery for large-scale energy storage due to its low cost and excellent performance. A solid electrolyte-based liquid lithium battery (called SELL battery) is a new type of molten-salt battery with enormous potential for stationary energy storage and extreme environment energy storage such as aerospace and deserts. It has a series of advantages, including the good thermal and chemical performance of the LLZTO electrolyte, lithium anode’s high theoretical specific capacity (3860 mA h g–1), and recharged high-capacity cathode material. For more stable operation and higher energy utilization efficiency of molten-salt batteries, we designed a thermal–electrochemical coupled 3D SELL battery module model. We successfully realized the module-level long-term (dozens of hours) transient simulation under different operating conditions. Results demonstrate the existence of an optimal charge–discharge rate, which minimizes the sum of the heat generated by the battery and heating plate (31% energy saving compared to battery standing). The heating plate’s variable power working mode is more flexible and effective than the constant power working mode. With the increasing thickness of the heat insulation board, energy consumption gradually reduces (energy consumption of which the thickness of heat insulation board equals 3 cm is 3.7 times that of a 12 cm one) and tends to be gentle. A dense array of batteries helps maintain battery temperature and different heating plate shapes have little effect on the average heating plate power. This paper successfully simulated the electrochemical and heat transfer processes of the SELL battery for the first time. It provided a general and efficient numerical simulation method for the molten-salt battery. The results obtained are conducive to improving the molten-salt battery’s stability and reducing the battery module’s energy consumption.

Operational strategy optimisation of VRB energy storage systems considering the dynamic characteristics of VRB in active distribution networks

Strategy optimisation of large-scale battery energy storage system (BESS) operation in active distribution networks (ADNs) is an actively pursued research topic concerned by electric power researchers. This study proposes a dynamic programming method (DPM)-based operational strategy optimisation of vanadium redox flow battery (VRB) ESSs for the comprehensive performance of ADNs considering the dynamic characteristics of VRB. The dynamic characteristics of VRB based on self-discharge rate, dynamic efficiencies, maximum absorption power, cycle life and apparent power are reasonably proposed to construct the operational restrictions of ESSs. VRB is safely and reasonably operated with high cycle life and ideal states by these dynamic operational restrictions. And then, DPM is used to decompose the multivariate optimisation problem into several univariate optimisation problems. Finally, different case studies showed that the developed operation strategy of VRB ESSs can greatly improve both the economy and the voltage quality of ADNs. Also, the curtailment rate of renewable energy in ADNs is greatly reduced by about 50% and VRB ESSs can get a perfect optimisation associated with a higher utilisation rate of about 0.8 and an ameliorative average efficiency of about 0.753.

Battery Energy Storage System Integration and Monitoring Method Based on 5G and Cloud Technology

The large-scale battery energy storage scatted accessing to distribution power grid is difficult to manage, which is difficult to make full use of its fast response ability in peak shaving and frequency modulation. With the rapid development of 5G and cloud technology, it is possible to realize interconnection of distributed battery energy storage system (BESS), cloud integration of energy storage system (ESS) and data edge computing. In this paper, a BESS integration and monitoring method based on 5G and cloud technology is proposed, containing the system overall architecture, 5G key technology points, system margin calculation. Therefore, rapid, accurate and flexible control of BESS can be realized, which make more use of BESS in peak shaving and shifting, new energy consumption, electric power bidding platform and other fields.

A Novel Battery Integration Method of Modular Multilevel Converter With Battery Energy Storage System for Capacitor Voltage Ripple Reduction

Modular multilevel converter with integrated battery energy storage system has been verified as a better choice for large-scale battery energy storage system. However, battery power and its unbalanced distribution in submodules lead to significant increase of capacitor voltage ripple. Larger submodule capacitance is required to maintain the ripple within reasonable limits, increasing the cost and volume of the system. To address the problem, this article proposes a novel battery integration method. Each battery pack is connected with two submodules that belong to upper and lower arm, respectively, through an isolated three-port dc-dc converter. The proposed method can ensure the power balance between upper and lower arm to eliminate fundamental circulating current and reduce capacitor voltage ripple. Three-port converters provide power channels for the fundamental power fluctuation of arms; thus, capacitor voltage ripple is further reduced. Then, the small-signal model of the proposed structure is built, and the control strategy is designed to realize both capacitor voltage ripple reduction and battery power control. Finally, a downscaled prototype is built and detailed experiment results verify the effectiveness of the proposed battery integration method and control strategy.

Operational benefit evaluation for frequency regulation application of large-scale battery energy storage

Operational benefit evaluation for frequency regulation application of large-scale battery energy storage

High-Performance NaVO3 with Mixed Cationic and Anionic Redox Reactions for Na-Ion Battery Applications

Sodium-ion batteries (NIBs) are a potential low-cost alternative to lithium-ion batteries for large-scale energy storage, but many high-capacity NIB cathode materials undergo irreversible structura...