Large-scale Battery Energy Storage Research Articles

Layered-Structure SbPO4/Reduced Graphene Oxide: An Advanced Anode Material for Sodium Ion Batteries

Sodium ion batteries are one of most promising alternatives to lithium ion batteries for large-scale energy storage, due to the high abundance and low cost of sodium in the earth. However, the lack of advanced electrode materials greatly affects their applications. Here, layered-structure SbPO4 is explored as an anode material for sodium ion batteries in terms of SbPO4 nanorods on reduced graphene oxide (SbPO4/rGO). In situ transmission electron microscopy images reveal the preferential expansion along the transverse direction of the nanorods upon the first discharging, which arises from the reduction of SbPO4 to Sb and the subsequent alloying of Sb as supported by in situ X-ray diffraction and selected area electron diffraction patterns. SbPO4/rGO exhibits a capacity retention of 99% after 100 cycles at 0.5 A g-1 both in half cells and in full cells. Its specific capacity at 5 A g-1 is 214 mA h g-1 in half cells or 134 mA h g-1 in full cells. Moreover, the energy density of the full cells at 1.2 kW kg-1total is still 99.8 W h kg-1total, very promising as an advanced electrode material.

Direct implementation of K3Fe(CN)6 as cathode materials of sodium-ion batteries

Transition metal cyanides are considered as a promising cathode candidate of sodium-ion batteries. Herein, we reported a direct implementation of commercial K3Fe(CN)6 (KFC) as active cathode material of SIBs by a simple recrystallization method. Our results suggest that by integrating conductive carbons (SuperP, abbreviated as SP) and multi-walled carbon nanotubes (CNTs) with KFC, an efficient conducting network could be well established for the utilization of KFC active components, thereby endows excellent cyclic and rate performances. Specifically, the KFC/SP/CNTs composite delivers its theoretical capacity of 81 mAh g−1 at 0.1C, and a reversible capacity of 75.6 mAh g−1 at 1C which maintains 62.6 mAh g−1 after 500 cycles. At ultrahigh rate of 12C, the capacity retention can reach 68% of initial. Our effort suggests that direct implementing industrial KFC as cathode materials for SIBs is highly feasible, which may provide a low-cost cathode candidate of sodium-ion batteries for large-scale energy storage.

Nickel-hydrogen batteries for large-scale energy storage.

Large-scale energy storage is of significance to the integration of renewable energy into electric grid. Despite the dominance of pumped hydroelectricity in the market of grid energy storage, it is limited by the suitable site selection and footprint impact. Rechargeable batteries show increasing interests in the large-scale energy storage; however, the challenging requirement of low-cost materials with long cycle and calendar life restricts most battery chemistries for use in the grid storage. Recently we introduced a concept of manganese-hydrogen battery with Mn2+/MnO2 redox cathode paired with H+/H2 gas anode, which has a long life of 10,000 cycles and with potential for grid energy storage. Here we expand this concept by replacing Mn2+/MnO2 redox with a nickel-based cathode, which enables ∼10× higher areal capacity loading, reaching ∼35 mAh cm-2 We also replace high-cost Pt catalyst on the anode with a low-cost, bifunctional nickel-molybdenum-cobalt alloy, which could effectively catalyze hydrogen evolution and oxidation reactions in alkaline electrolyte. Such a nickel-hydrogen battery exhibits an energy density of ∼140 Wh kg-1 (based on active materials) in aqueous electrolyte and excellent rechargeability with negligible capacity decay over 1,500 cycles. The estimated cost of the nickel-hydrogen battery based on active materials reaches as low as ∼$83 per kilowatt-hour, demonstrating attractive characteristics for large-scale energy storage.

Ultrafine CoSe nano-crystallites confined in leaf-like N-doped carbon for long-cyclic and fast sodium ion storage

Considerable efforts have been devoted to developing sodium-ion batteries for large-scale energy storage due to the high abundance and low cost of sodium resources. However, the inferior cyclability and reaction kinetics of electrodes toward sodium ions still impedes their further development. In this study, we designed a two-dimensional (2D) composite where ultrafine CoSe nano-crystallites were confined in N-doped carbon (CoSe/NC-L) to attain excellent cycling performance and fast sodium ion storage. The CoSe/NC-L was successfully prepared through a high-temperature reaction of leaf-like Co-based ZIF (ZIF-L) and Se powder. It is demonstrated that the particle size of Se powder plays an important role in the formation of ultrafine CoSe nano-crystallites and encapsulated configuration. The combined merits of ultrafine CoSe and encapsulation into 2D NC matrix effectively enhance reaction kinetics, accommodate volume change expansion of CoSe and inhibit the formation of unstable SEI. Therefore, the CoSe/NC-L composite displayed high initial specific capacity of 530 mAh g−1 and Coulombic efficiency of 67.2% at 0.2 A g−1. Notably, superior capacity retention of 82.2% with stable Coulombic efficiency of 97.0% is achieved at 0.5 A g−1 after 150 cycles in NaClO4 electrolyte system. This work casts a new light on the smart design of metal selenide electrode materials for sodium ions batteries.

Techno-economic evaluation of a hybrid CSP + PV plant integrated with thermal energy storage and a large-scale battery energy storage system for base generation

Chile presents a combination of favorable climatic conditions which result in the highest levels of solar irradiation in the world. In this paper, the performance of a hybrid CSP + PV plant at utility-scale integrated with a large-scale Battery Energy Storage System (BESS) located in northern Chile was studied. The model considered a solar power tower integrated with a two-tank molten salt direct TES and a fixed-angle PV plant coupled to a BESS to deliver a baseload of 100 MWe. A parametric analysis was carried out in terms of the PV size, solar multiple, TES hours capacity, and BESS size. The hybrid plant performance was studied in terms of the LCOE and the capacity factor. The minimum LCOE configurations were identified and a sensibility analysis was carried out to evaluate the effect of a cost reduction of the BESS in the hybrid plant configuration for different BESS sizes. Results showed that current investment costs of the storage section of the BESS make unprofitable its integration to the hybrid plant, so, it is required a reduction of approximately 60–90% of the storage cost (based on a reference value of 300 USD/kWh) to achieve competitive LCOEs in comparison to those obtained for a hybrid plant without BESS. Under this BESS cost reduction scenario, it was found a solutions domain with different hybrid plant configurations, which allow to integrate and complement the production of both CSP and PV plants with both storage types in a synergetic operation. Also, a comparative study evaluating the differences between implementing a fixed-tilt PV configuration or a one-axis tracking system in the hybrid plant scheme was carried out, obtaining that the annual production of the hybrid plant increases by no more than 5% with the tracking system, while the LCOE is reduced up to -1.98% due to a decrease of the BESS participation in the total output. These results indicate that the minimum LCOE configurations of a hybrid CSP + PV plant with tracked PV arrays (given a BESS size) could result in smaller PV plants, since the PV production increases in comparison to that with a fixed-tilt PV configuration.

On-grid batteries for large-scale energy storage: Challenges and opportunities for policy and technology

ABSTRACT

On optimal participation in the electricity markets of wind power plants with battery energy storage systems

The recent cost reduction and technological advances in medium- to large-scale battery energy storage systems (BESS) makes these devices a true alternative for wind producers operating in electricity markets. Associating a wind power farm with a BESS (the so-called virtual power plant (VPP)) provides utilities with a tool that converts uncertain wind power production into a dispatchable technology that can operate not only in spot and adjustment markets (day-ahead and intraday markets) but also in ancillary services markets that, up to now, were forbidden to non-dispatchable technologies. What is more, recent studies have shown capital cost investment in BESS can be recovered only by means of such a VPP participating in the ancillary services markets. We present in this study a multi-stage stochastic programming model to find the optimal operation of a VPP in the day-ahead, intraday and secondary reserve markets while taking into account uncertainty in wind power generation and clearing prices (day-ahead, secondary reserve, intraday markets and system imbalances). A case study with real data from the Iberian electricity market is presented.

Atomic visualization of a non-equilibrium sodiation pathway in copper sulfide

Sodium ion batteries have been considered a promising alternative to lithium ion batteries for large-scale energy storage owing to their low cost and high natural abundance. However, the commercialization of this device is hindered by the lack of suitable anodes with an optimized morphology that ensure high capacity and cycling stability of a battery. Here, we not only demonstrate that copper sulfide nanoplates exhibit close-to-theoretical capacity (~560 mAh g–1) and long-term cyclability, but also reveal that their sodiation follows a non-equilibrium reaction route, which involves successive crystallographic tuning. By employing in situ transmission electron microscopy, we examine the atomic structures of four distinct sodiation phases of copper sulfide nanoplates including a metastable phase and discover that the discharge profile of copper sulfide directly reflects the observed phase evolutions. Our work provides detailed insight into the sodiation process of the high-performance intercalation–conversion anode material.

大規模蓄電池システムの高効率有効電力指令配分手法に関する考察

大規模蓄電池システムの高効率有効電力指令配分手法に関する考察

시분할 스위칭 기법을 이용한 양방향 DC/DC 컨버터에 관한 연구

A number of new and renewable energy power plants have currently been under construction to cope with fossil fuel depletion, while various large-scale battery energy storage systems have been configured to complement the characteristically unstable output of new and renewable energy. In the meantime, as the scale of energy storage system increases, there is an urgent demand for bidirectional charge/discharge converters with large capacities, and relevant researches are actively going on. Interleaved converter is most generally used for this purpose because it enables not only the reduction of output current ripple, but also the increase of capacity through the parallel configuration of inductor and switch and diode. This paper proposes a new concept of DC/DC converter that allows the sharing of inductor and output capacitor by using a multi-phase switch. However, interleaved converter has the weak points that size and unit price increase as capacity increases, and that effective switching frequency is limited. The proposed DC/DC converter has a structure that can increase the effective switching frequency of not only output capacitor but inductor as well, and its merit of enabling the reduction of inductor capacity by reducing inductor current ripple was demonstrated.

Environmental impacts of electricity generation for Graciosa Island, Azores

The Graciosa project combines a large scale battery energy storage system with renewable electricity generation from wind power and photovoltaics in a hybrid power plant to reduce the environmental impacts caused by the previous electricity generation by 100 % Diesel combustion on Graciosa Island, Azores. The goal of this contribution is to assess and compare the selected environmental impacts related to the electricity generation of the previous and the new system by using Life Cycle Assessment. To accomplish this goal, all energy and material flows that occur during production, use and recycling/disposal of the electricity generating systems are quantified and evaluated. The results of the Life Cycle Assessment show a reduction of environmental impacts of approx. 43% due to the transformation to the hybrid electricity supply system with high shares of renewable energies (65%). In the new electricity supply system, the majority of environmental impacts (>60%) is still caused by the remaining Diesel based electricity generation. Environmental impacts, which are associated with the construction of the large scale battery energy storage system, account for only 6% of total impacts. Wind power and photovoltaics account for 18% and 14%, respectively.

Reliability Evaluation of Large Scale Battery Energy Storage Systems

This paper analyzes the reliability of large scale battery storage systems consisting of multiple battery modules. The whole system reliability assessment is based on the reliability evaluation of system components including individual battery modules and power electronic converters. In order to evaluate the reliability of a battery module, a reliability model based on the state of health of individual battery cells is introduced. The state of health of a battery cell is calculated based on the capacity fade of the cell using a weighted Ampere-hour throughput method. A universal generating function-based method is then introduced to evaluate the reliability of the battery module. The reliability model of dc/ac power electronic converters is also presented in this paper. The reliability analysis is conducted for battery storage systems with different system configurations and management strategies, and the influence of system configuration on the reliability of battery system is studied. Comparative studies are conducted for a classic battery energy storage system (BESS) and a reconfigurable BESS (RBESS) to demonstrate the advantages of having a reconfigurable system topology. The comparison results show that the proposed RBESS has higher system reliability and more power outputs than the classic BESS.

Renewable energies for Graciosa Island, Azores – Life Cycle Assessment of electricity generation

The Graciosa project combines a large scale battery energy storage system with renewable electricity generation from wind power and photovoltaics in a hybrid power plant to reduce the environmental impacts caused by the previous electricity generation by 100 % diesel combustion on Graciosa Island, Azores. The results of a Life Cycle Assessment show a reduction of environmental impacts of approx. 43 % due to the transformation to the hybrid electricity supply system with high shares of renewable energies (65 %). In the new electricity supply system, the majority of environmental impacts (> 60 %) is still caused by the remaining diesel based electricity generation. Environmental impacts, which are associated with the construction of the large scale battery energy storage system, account for only 6 % of total impacts. Wind power and photovoltaics account for 18 % and 14 %, respectively.

Real-world operating strategy and sensitivity analysis of frequency containment reserve provision with battery energy storage systems in the german market

Large-scale battery energy storage systems (BESS) have become increasingly interesting to provide ancillary services for the electricity grid. Especially the German frequency containment reserve (FCR) market which is organized by the German transmission system operators (TSO) is attractive for BESS. Because of its importance for the system stability, FCR has to be provided continuously with 100% availability. Due to the limited energy capacity of BESS, an operating strategy is required to enable continuous FCR provision. The German TSOs have defined several requirements that BESS have to comply with as well as degrees of freedom (DoF) to enable corrective measures such as selective recharging for an operating strategy. This paper presents a sensitivity analysis of different operational parameters based on an operating strategy developed within the M5BAT (Modular Multi_Megawatt Multi-Technology Medium-Voltage Battery Energy Storage System) project. Within this project the construction and operation of a 5MW hybrid BESS with five different battery technologies is realized. As this BESS will mainly be operated in the German FCR market, it is used as reference for this paper. The developed operating strategy considers the TSO’s FCR requirements and DoF and is fully applicable to the German FCR market. Within this paper it is explained how corrective measures have to be triggered in order to comply with the requirements. A model of the M5BAT BESS, which comprises various battery technologies and an energy management system (EMS) for load allocation among multiple battery strings, is introduced. Simulations of FCR operation with measured frequency data of the year 2014 are presented. The influence of the lead time and duration of corrective measures, the EMS and the FCR requirements on compliance with the FCR requirements, amount of corrective measures, resulting energy throughput, state-of-energy (SOE) distributions and cycle numbers are investigated. The results show a significant impact of all parameters. It is found that velocity and flexibility of corrective measures (e.g. recharging) and an efficient EMS are prerequisites for FCR operation with BESS under the applicable regulation. Additionally, the results indicate that the overall benefits of FCR provision with BESS could be improved with an adjustment of the requirements (30-min-criterion).

Conductive graphite fiber as a stable host for zinc metal anodes

Zn metal with high theoretical capacity (820mAhg−1), environmental-friendly properties and low cost is very competitive to be as an anode for aqueous batteries. However, uncontrollable growth of dendritic zinc in these batteries during plating/stripping process of zinc ions not only leads to a low Coulombic efficiency but also brings safety hazards, which have obstructed the application of secondary Zn-based batteries. Here we use high conductive carbon fiber-graphite felt (GF) as collector and electrodeposit zinc under constant voltage to fabricate a self-supported Zn@GF negative electrode. The graphite felt provides this anode larger electroactive area to transport electrons faster and loads zinc in a more event way, thus preluding the zinc plating in several specific directions. This composite anode offers an efficient solution to get a dendrite-free cycling behavior of zinc-based batteries and might be promising in advanced aqueous batteries for large-scale energy storage.

Crystallite Size Control of Prussian White Analogues for Nonaqueous Potassium-Ion Batteries

Nonaqueous potassium-ion batteries have emerged as possible low-cost alternatives to Li-ion batteries for large-scale energy storage, owing to their ability to use graphitic carbon as the negative electrode. Positive electrode materials remain a challenge. Here, we report control of the crystal dimensions of the Prussian white hexacyanoferrate (HCF), K1.7Fe[Fe(CN)6]0.9, using solution chemistry to obtain either nano, submicron, or micron crystallites. We observe a very strong effect of crystallite size on electrochemical behavior. The optimal cathode material comprised of 20 nm crystallites delivers a close-to-theoretical reversible capacity of 140 mAh g–1 with two well-defined plateaus at 4.0 and 3.2 V vs K/K+ upon discharge. Slightly inferior electrochemical behavior is observed for crystallites up to ∼160–200 nm in diameter, but unlike the analogous Na HCFs, micron-sized crystals show very limited capacity. For the nanosized crystallites, however, the energy density of ∼500 Wh kg–1 is comparable to tha...

A High Energy-Density, Low-Cost Hybrid Organic Flow Battery

In this work, a novel hybrid flow battery system is proposed. In the negative side, we explore a vitamin-based molecule that has never been tested in a flow battery before. As a quinone derivative, it undergoes a reversible two-electron redox reaction at 0.05 V vs. standard hydrogen electrode. The solubility of the molecule is higher than 4.5 M, leading to a volumetric energy density of 120 Wh/L, when paired with a lead dioxide/lead sulfate electrode [1]. Such a hybrid flow battery achieves a cell voltage of 1.68 V and can be cycled stably for over 50 cycles without significant capacity loss. The adoption of solid-state lead-based electrode eliminates the need of an expensive ion exchange membrane. More importantly, as the molecule has been mass-produced at low cost, the cost of this novel system is much lower than current existing flow battery systems [2-3]. It is a promising candidate for both large scale energy storage usages and mobile applications in both perspectives of cost and energy density. [1] Leung, P. K., Qian Xu, and T. S. Zhao. "High-potential zinc–lead dioxide rechargeable cells." Electrochimica Acta 79 (2012): 117-125. [2] Zhang, Mengqi, et al. "Capital cost sensitivity analysis of an all-vanadium redox-flow battery." Journal of The Electrochemical Society 159.8 (2012): A1183-A1188. [3] Zeng, Y. K., et al. "A comparative study of all-vanadium and iron-chromium redox flow batteries for large-scale energy storage." Journal of Power Sources 300 (2015): 438-443.

High-Performance Flow-Field Structured Iron-Chromium Redox Flow Batteries for Large-Scale Energy Storage

The conventional flow-through structured ICRFBs have to employ thick carbon felts (typically 3.0-6.0 mm) as the electrodes to circumvent high pump loss, which inevitably results in high ohmic resistance, low operating current densities (around 80 mA cm-2) as well as cumbersome and costly cell stacks. Increasing the operating current density/power density is an effective strategy to reduce the cell stack size and cost. Recently, a flow-field structured ICRFB with thin carbon paper electrodes demonstrates a significantly increased operating current density of 200 mA cm-2 at the energy efficiency of 79.6% mainly due to the reduced ohmic resistance [1]. Further enhancement of ICRFB performance is achieved by adopting the interdigitated flow fields, which enhances the active species transport at the porous electrode and enables a more uniform catalyst distribution [2]. In addition, the effects of design parameters including electrode compression ratio, electrode pretreatment intensity, membrane thickness and catalyst loading on the ICRFB charge-discharge performance have been are investigated [3]. Results show that: i) with a thin NR-211 membrane and a high electrode compression ratio of 62.5%, the operating current density of the ICRFB can reach as high as 480 mA cm-2 at an energy efficiency of higher than 80%; ii) the bismuth catalyst loading has insignificant effect on the battery performance in the range of 0.52-10.45 mg cm-2; iii) the moderately oxidative thermal pretreatment of the electrode improves the energy efficiency compared to the as-received electrode while the electrode prepared with a harsh pretreatment deteriorates the battery performance; and iv) for the present ICRFBs operating at both 25oC and 65oC, the dominant loss is identified to be ohmic loss rather than kinetics loss.

Analysis and Fault Control of Hybrid Modular Multilevel Converter With Integrated Battery Energy Storage System

A modular multilevel converter (MMC) integrated with split battery modules has been verified a better choice for the large-scale battery energy storage system (BESS). In this case, both ac grid and dc grid can exchange power with the BESS while the power transfer between ac and dc grids can be decoupled. However, without the ability to ride through dc grid fault, the performance and reliability of whole system will be reduced. Therefore, a hybrid MMC (HMMC) with integrated BESS (HMMC-BESS) is proposed in this paper. Then the batteries can exchange power with the normal grid continuously and independently, even when short-circuit fault condition happens on ac or dc grid. However, the traditional control schemes are no longer suitable for the fault modes. In this paper, the configuration, modeling, and operation modes of HMMC-BESS are discussed first. After that, both ac and dc grid fault modes of HMMC are analyzed and control schemes of corresponding mode are presented. In addition, novel balancing methods for the state-of-charge and voltage allocation scheme are proposed according to different operation modes. Finally, a downscaled prototype is built in laboratory to verify the proposed control scheme.

A novel iron-lead redox flow battery for large-scale energy storage

Abstract The redox flow battery (RFB) is one of the most promising large-scale energy storage technologies for the massive utilization of intermittent renewables especially wind and solar energy. This work presents a novel redox flow battery that utilizes inexpensive and abundant Fe(II)/Fe(III) and Pb/Pb(II) redox couples as redox materials. Experimental results show that both the Fe(II)/Fe(III) and Pb/Pb(II) redox couples have fast electrochemical kinetics in methanesulfonic acid, and that the coulombic efficiency and energy efficiency of the battery are, respectively, as high as 96.2% and 86.2% at 40 mA cm−2. Furthermore, the battery exhibits stable performance in terms of efficiencies and discharge capacities during the cycle test. The inexpensive redox materials, fast electrochemical kinetics and stable cycle performance make the present battery a promising candidate for large-scale energy storage applications.