Stationary Energy Storage Applications Research Articles

Techno-economic assessment of isolated micro-grids with second-life batteries: A reliability-oriented iterative design framework

Reusing lithium-ion batteries retired from electric vehicles (EVs) has received great attention as the performance of these batteries is still adequate for many stationary energy storage applications, such as micro-grids (MGs). To date, the economic and technical performance of second-life batteries (SLBs) in isolated MG systems remains obscure. Hence, this study focuses on the economic assessment of SLBs in an isolated 100% renewable MG, in order to identify a profitable application that promotes SLBs. The MG capacity design parameters are obtained by a two-stage chance-constrained stochastic optimization framework. To enhance the robustness of the MG design, a reliability-oriented iterative design process is proposed. This process involves continuous updates to the MG design, guided by validation results, until all specified requirements are satisfied. The lifetime of SLBs is determined using a semi-empirical degradation model seamlessly integrated into the validation process. Economic comparisons between SLBs and first-life batteries (FLBs) are conducted under identical design requirements, with consideration given to estimating the “price ceiling” and the impact of market factors. The results show that SLBs prove to be a more cost-effective option, especially when there is a demand for high reliability standards and the local electricity prices are comparatively lower.

Compatibility and effect of capacity ratios between Na3V2(PO4)3 and hard carbon in highly concentrated sodium bis (fluorosulfonyl) imide electrolyte

From the standpoint of preserving the Earth's resources and ensuring the long-term viability of humanity, it is imperative to transition away from lithium-ion batteries. High-performance and safe sodium-ion batteries have recently emerged as promising advanced batteries for application in stationary energy storage, attributed to their low cost and abundance of sodium ion. We demonstrate the compatibility and effect of the negative-positive capacity ratio in full-cell Na3V2(PO4)3 and hard carbon in high-concentration electrolytes. Thanks to the excellent oxidation stability of the electrolyte, during 100 cycles, the full cell with a negative-positive capacity ratio of 1.1 demonstrated a consistent capacity of around 100 mAh g-1 with a capacity retention of 90.7%, whereas the full cell with a ratio of 1.0 showed a steady discharge capacity of roughly 90 mAh g-1 with a capacity retention of approaching 100% at a current density of C/5.

Sodium Polymer Electrolytes: A Review

Lithium-based electrolytes are, at least from a thermodynamic standpoint, the most suitable ion-transport materials for energy storage systems. However, lithium-based ionic conductors suffer from safety concerns, and the limited availability of lithium in the Earth’s crust is at the root of the need to consider alternative metal ions. Notably, sodium stands out as the sixth most-prevalent element; therefore, when considering mineral reserves, it as a very attractive candidate as an alternative to the status quo. Even if the specific energy and energy density of sodium are indeed inferior with respect to those of lithium, there is substantial economic appeal in promoting the use of the former metal in stationary energy storage applications. For these reasons, the promise of sodium is likely to extend to other commercial applications, including portable electronics, as well as hybrid and electric vehicles. Widely used organic liquid electrolytes, regardless of their chosen metal cation, are disadvantageous due to leakage, evaporation, and high flammability. Polymer electrolytes are acknowledged as the most effective candidates to overcome these obstacles and facilitate the advancement of next-generation energy storage applications. In this contribution, an in-depth and comprehensive review of sodium polymer electrolytes for primary and secondary batteries is proposed. The overarching goal was to gain insight into successful synthetic strategies and their implications for conduction parameters and conductivity mechanisms. The focus lies on solid, gel, and composite polymer electrolytes. Our hope is that the proposed discussion will be helpful to all operators in the field, whether in tackling fundamental research problems or resolving issues of practical significance.

Integrating Micro-Patterned Flow Fields into Electrode Architecture Via Non-Solvent Induced Phase Separation for High Performance Redox Flow Batteries

To facilitate increasing penetration of intermittent renewables in the energy mix, there is a growing need for energy storage technologies. Redox flow batteries (RFBs) have attracted significant attention in recent years due to their suitable characteristics for long-duration stationary energy storage applications. However, the wider adoption of RFB systems is still limited by the capital cost, to which the reactor stack is a large contributor[1]. Further cost reduction can be achieved by reducing kinetic, mass-transfer, and ohmic losses to improve the stack performance. Porous electrodes are key components within the battery stack, providing active sites for electrochemical reactions, and transport pathways for active species. Commercially available carbon-fiber electrode architectures include carbon paper, carbon felt, and carbon cloth. They have a highly porous structure, but their relatively low surface area and low hierarchical fiber orientation increase both electrochemical and pumping losses[2]. There is still a need to develop a low-cost porous electrode that meets the requirements of high active surface area and facile electrolyte transport to enhance battery performance and system efficiency.Non-solvent induced phase separation (NIPS) is a manufacturing route in the field of membrane technology, which is widely used to fabricate asymmetric membranes[3]. Recently this route has also been used to fabricate non-fibrous porous electrodes[4]. The microstructure of NIPS electrodes is largely influenced and controlled by the solvent/non-solvent exchange rate at the interface between a polymer solution and a coagulation bath. When the phase exchange process is slow, segregation is delayed. This type of segregation generally results in a sponge-like, relatively dense structure[5]. This sponge-like structure has the advantage of small pore size and high surface area, but also has poor hydraulic permeability and high mass-transfer losses. The trade-off between surface area and permeability needs to be further optimized.In the present study, inspired by the flow field designs widely used in RFBs to guide the electrolyte flow paths for low pressure drop, uniform electrolyte distribution, and high electrochemical performance[6], we propose a strategy to imprint micro-patterned flow fields directly into the electrode architecture during NIPS processing to improve mass transfer properties. NIPS polymer films were cast onto molds with specific micro-patterns, and the resulting micro-channels can be preserved in the electrodes after carbonization. To verify the effectiveness of the micro-patterned electrodes, here, we investigate two selected micro-patterned designs. The groove-patterned electrodes were combined with flow-through flow fields (FT-FFs) for in-plane mass transport optimization, and the pillar-patterned electrodes were combined with interdigitated flow fields (IDFFs) for through-plane flow optimizations[7]. Two geometric sizes of the micro-patterns were considered in each design. The pore sizes and distributions of the micro-patterned electrodes were determined by mercury intrusion porosimetry. The hydraulic permeability of the electrodes was evaluated by half-cell pressure drop measurements, and the electrochemical specific surface area was determined through electrochemical impedance spectroscopy under non-faradaic conditions. In addition, we performed electrochemical battery tests with symmetric iron RFB (0.5 M Fe2+/Fe3+, 2 M HCl) cells and vanadium full-cells (1.6 M V active species at 50% state-of-charge). It was found that due to the small pore size (e.g., ~1 μm) and narrow pore size distribution of the sponge-like NIPS structure, the main contribution to the total losses in electrodes without micro-patterns in electrochemical performance comes from mass-transfer. Electrodes with groove and pillar patterns can help reduce the pressure drop and improve mass transfer properties. Pillar-patterned electrodes with the combination of IDFF show high overall electrochemical performance with greatly reduced mass transport resistances. At an electrolyte velocity of 10 cm/s, the total resistances for kinetic and mass transfer are less than 0.1 Ω·cm2 in symmetric iron cell tests. Compared to the activated commercial electrode (e.g., 2-layer Freudenberg H23 carbon paper, thermally treated at 450 oC for 12 h), the total resistances for kinetic and mass transfer are reduced by ~60%, which shows great potential for adoption in next generation high-performance RFB systems. References J. Noack, L. Wietschel, N. Roznyatovskaya, K. Pinkwart, J. Tübke, Energies, 9, 627 (2016).A. Forner-Cuenca, F.Brushett, Current Opinion in Electrochemistry, 18, 113-122 (2019).H. Wang, J. Jung, J. Kim, S. Kim, E. Drioli, Y. Lee, Journal of Membrane Science, 574, 44-54 (2019).C. Wan, R. Jacquemond, Y. Chiang, K. Nijmeijer, F. Brushett, A. Forner-Cuenca, Advanced Materials, 33, 2006716 (2021).D. Wang, J. Lai, Current Opinion in Chemical Engineering, 2, 229-237 (2013).X. Ke, J. Prahl, J. Alexander, J. Wainright, T. Zawodzinski, R. Savinell, Chemical Society Reviews, 23, 8721-8743 (2018).V. Muñoz-Perales, P. García-Salaberri, A. Mularczyk, S. Ibáñez, M. Vera, A. Forner-Cuenca, ChemRxiv, (2023).

Long-Life Lead-Carbon Batteries for Stationary Energy Storage Applications.

Owing to the mature technology, natural abundance of raw materials, high recycling efficiency, cost-effectiveness, and high safety of lead-acid batteries (LABs) have received much more attention from large to medium energy storage systems for many years. Lead carbon batteries (LCBs) offer exceptional performance at the high-rate partial state of charge (HRPSoC) and higher charge acceptance than LAB, making them promising for hybrid electric vehicles and stationary energy storage applications. Despite that, adding carbon to the negative active electrode considerably enhances the electrochemical performance. However, carbon brings some adverse effects, such as the severe hydrogen evolution reaction (HER) in the NAM due to the low overpotential of carbon material, promoting severe water loss in LCBs. From a practical application point of view, the irreversible sulfation of the negative active material (NAM) and extreme shedding and softening of the positive active material (PAM) are the main obstacles for next-generation LCBs. Recently, a lead-carbon composite additive delayed the parasitic hydrogen evolution and eliminated the sulfation problem, ensuring a long life of LCBs for practical aspects. This comprehensive review outlines a brief developmental historical background of LAB, its shifting towards LCB, the failure mode of LAB, and possible potential solutions to tackle the failure problems. The detailed LCB's development towards long life was discussed in light of the reported literature to guide the researcher to date progress. More emphasis was directed toward the new applications of LCBs for stationary energy storage applications. Finally, state-of-the-art progress and further research gaps were pointed out for future work in this exciting era.

Toward Commercial Cylindrical Anode Free Li-Metal Batteries: Electrochemical Study and Improvement

Lithium-ion batteries (LIBs) are one of the favorite energy storage devices that are applied to mobile and stationary energy storage applications. The widespread use of Li-ion batteries requires an increase in the energy density of each battery cell. Anode-free Li-ion Batteries (AFLIBs) are new types of LIBs models that offer high energy density. However, there are still many challenges in fabricating AFLIBs toward commercial use, mainly improving the battery cycle and the efficiency of intercalation/deintercalation of Li-ion between two electrodes. In this research, the fabrication of AFLIBs is studied, optimized, and integrated with cathode materials to be commercial cylindrical full-cell LIBs. The comparison of an active cathode material between LiFePO4 (LFP) and NMC622 showed that NMC622 performed better than LFP. The optimum condition of cathode materials coating thickness is 200 microns achieving 2.75 mAh cm-2 of area capacity. Furthermore, the gold platting strategy is proposed to modify the Cu foil surface to improve the electrical performance and stability of AFLBs. As a result, the control gold plating with 5 nm thickness increases the full-cell capacity of AFLBs to 142.89 mAh g-1 with a capacity retention percentage of 95.41% after five cycles.

Towards Safer All-Solid-State Lithium Metal Batteries by an Artificial Protection Layers

Lithium ion batteries (LIB) are representing a milestone in electrochemical energy storage and are still the state-of-the-art battery system for various mobile and stationary energy storage applications. However, the practical energy density of LIBs starts to reach an asymptotic limit. Beside LIBs, an auspicious variety of battery systems comprising a better option for specific applications in terms of e.g. energy density, so establishing a diversity of specific battery systems for specific applications is a good strategy.[1 ] After initially paving the way for the LIB, the lithium metal battery (LMB) experiences a revival due to an outstanding theoretical specific capacity (3 860 mAh g−1) and low electrochemical potential (−3.04 V vs. SHE). However, continuous electrolyte consumption, the formation of an inhomogeneous SEI and high surface area lithium (HSAL), whose growth is induced by the heterogeneous and fragile structure of the SEI film, are still dominant challenges that need to be overcome. The liquid electrolytes also deal with safety issues like risk of leakage and flammability. The combination of Li metal with solid polymer electrolytes (SPE) could supress HSAL formation and avoid those safety hazards. However, SPEs deal with poor ionic conductivity at room temperature (10−8 S cm−1 ≤ σ ≤ 10−5 S cm−1) and, additionally, it is necessary to control the Li morphology during electrodeposition/dissolution to realize high-energy all-solid-state batteries (ASSB) based on Li metal anodes.[2 ,3 ] Several artificial protective coatings have been proposed to improve the LMA/SPE interface by facilitating the Li ion flux, promoting a homogeneous Li electrodeposition/dissolution and protecting the LMA against electrolyte degradation as well as enhancing the Li wetting interface. The SPE induces a more flexible interphase that withstands the volume change. Recently, metal oxides coated by atomic layer deposition (ALD) have gained attention due to a great thickness control, the possibility of monolayer deposition as well as a consequential homogeneity of the deposited protection layer. Furthermore, ALD is suitable for roll-to-roll coatings which is feasible for industrial application.[3,4 ] Herein, the setup of Li-metal-polymer batteries (LMP® technology) commercialized by Blue Solutions and applied in their “blue cars” (30 kWh, 100 Wh kg-1) was modified in several points. Li metal was coated with a metal oxide via atomic layer deposition (ALD) to form an intermetallic phase as protective layer and to improve the Li+ flux. The artificial protective coating at Li metal was combined with a PEO- and/or polyether-based SPE and the effect of the modifications on the electrochemical performance in different ASSB setups was investigated and characterized.[1] Placke, T.; Kloepsch, R.; Dühnen, S.; Winter, M. Lithium ion, lithium metal, and alternative rechargeable battery technologies: the odyssey for high energy density. Journal of Solid State Electrochemistry 2017, 21, 1939-1964.[2] Cheng, X.-B.; Zhang, R.; Zhao, C.-Z.; Zhang, Q. Toward Safe Lithium Metal Anode in Rechargeable Batteries: A Review. Chemical Reviews 2017, 117, 10403-10473.[3] Han, Z.; Zhang, C.; Lin, Q.; Zhang, Y.; Deng, Y.; Han, J.; Wu, D.; Kang, F.; Yang, Q. H.; Lv, W. A Protective Layer for Lithium Metal Anode: Why and How. Small Methods 2021, 5, 2001035.[4] Han, Y.; Liu, B.; Xiao, Z.; Zhang, W.; Wang, X.; Pan, G.; Xia, Y.; Xia, X.; Tu, J. Interface issues of lithium metal anode for high‐energy batteries: Challenges, strategies, and perspectives. InfoMat 2021, 3, 155-174.

(Digital Presentation) Data-Driven Prognosis of Lithium-Ion Batteries Thermal Runaway Early Warning and Detection

Li-ion batteries (LIBs) are becoming ubiquitous in portable, stationary, and electrical energy storage applications that power various devices, from cell phones to the zero-emission plane. Market research suggests the $26.9 billion-a-year (2018) worldwide LIB market could reach $107 billion-a-year by 2025. Taking electric vehicles (EVs) for example, according to the Electric Drive Transportation Association (EDTA), the number of EV sales in the United States market has increased from 345 vehicles in 2010 to 331,617 in 2019, with a total cumulative number of 1.44 million vehicles over the ten-year sales period. This trend has also been observed in the global market as EVs' sales reached 2.1 million worldwide in 2019, boosting the stock to 7.2 million. Although the COVID-19 pandemic dramatically affected the global EV market and prompted the market to plummet over the year 2020 relative to 2019. The global EVs stock projections are expected to increase from 7.2 million to 14 million in 2025 and 25 million in 2030, accounting for 10% of global passenger vehicle sales in 2025 and 28% in 2030. Despite rapidly skidding into the EV era - a technical fait accompli- significant obstacles to vehicle electrification and adoption, especially the safety of their batteries, continue to threaten that future. The risk of anomaly generation and evolution (e.g., thermal runaway and exploration) is currently a major safety concern and challenge in applications powered by LIBs.The traditional first-principle simulations and comprehensive experiments are time-consuming or less effective in detecting and predicting the above problems induced by a synergistic effect of multiple degradation mechanisms. The above challenge eventually necessitates predictive or prognostic capability for Prognostics and Health Monitoring (PHM) under a complexly hostile working environment.This proposal will break away from existing practices, and instead, for the first time, the proposed data-driven prognosis (DDP) requires the assumption of the existence of a conservation principle but does not require a priori knowledge of the key mechanisms and boundary conditions. Alternatively, the exact form of the conservation functional is only specified locally, in the neighborhood of each observation point (and is assumed to be piecewise quadratic in the current work), whereas its global form remains unknown. The conservation principle is then defined as the minimization of system curvature at each observation point. The DDP methodology is based on the local curvature of the mathematical manifold representing the Euler-Lagrange governing equation of a system. The curvature represents a derivative of the total energy with respect to sensed variables, and instability is anticipated whenever the curvature exceeds a critical threshold, denoted by the inverse of the local length-scale of the manifold (or its extrinsic curvature). The length-scale, in turn, is calculated by solving the first moment of the state-space description (conservation of linear momentum) based on two consecutive time instants of measurements. In another sense, the DDP technique can estimate a mass normalized Energy Exchange Amplitude (EEA) that also represents a scaled “entropy rise” of the system. After acquiring the input data from the literatures, they were fed into DDP in a continuous order separated by each time step. At each time step, two consecutive time instances were considered that are sufficient to make the prognostication. The results of the simulation using the DDP are shown below. First the progression of PDI which shows the percentage of points that have reached different path dependence index (PDI) markers as shown in Figure 1 (a). It signifies the instants when the battery shows local instabilities. As shown in the figure, battery starts to show local instability from time instant 20 and beyond, highlighting the instability's progression. The chain length (CL) values and residual curvature information were analyzed as well and shown in Figure 1 (b) along with other criterias. As illustrated in the Figure, at time instant 10, the system crosses the critical chain length threshold and intensifies around time instance 20. Furthermore, the residual curvature (RC) value exceeds the critical threshold at time instance 19 and 21. The moment when all three criterias were met, the battery is expected to fail which is time instance 21 as shown in the Figure. Figure 1

Zinc/ Manganese Oxide Aqueous Electrolyte Batteries: Electrochemical Reaction Mechanisms Beyond Ion Insertion

The consistent delivery of clean electrical energy is a global challenge where the current electric grid infrastructure distributes electrical energy from the generation source to the end user. Widespread integration of inherently intermittent renewable energy sources such as wind and solar into the electric grid electrical energy storage into the electric grid demands incorporation of energy storage. Further, energy storage would enable control over when the electrical energy is used improving grid reliability and resiliency. Thus, stationary energy storage for the electric grid is a critical and timely application for batteries.Rechargeable aqueous zinc/ manganese oxide (Zn/MnO2) batteries are an appealing target for scalable stationary energy storage applications due to their low cost, safety, and environmentally benign components. Notably, manganese oxide is a versatile material where several polymorphs are viable cathode materials in aqueous zinc ion batteries. However, there is need for more complete understanding of the electrochemical reaction mechanisms, to continue to advance the system. This presentation will feature investigations of the reaction mechanisms with a focus on operando methods. X-ray diffraction, Mn K-edge X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) measurements supported by ex situ transmission electron microscopy (TEM) will be presented. The findings provide a foundation for advancing the battery systems based on aqueous electrolyte zinc anode chemistries suitable for scalable stationary energy storage.

In Situ Mechanical Measurements in Vanadium Pentoxide Cathodes for Aqueous Zinc-Ion Batteries during Battery Cycling

Aqueous rechargeable zinc-ion batteries (AZIBs) are currently gaining traction as a potential successor to lithium-ion batteries for use in large-scale, stationary energy storage applications due to their inherent safety, low environmental impact, and low-cost. Recent advances have made breakthroughs in these anode and electrolyte stability; however, cathode development still lags preventing the commercial use of AZIBs. Vanadium pentoxide (V2O5) shows promise as a cathode material due to its low cost, environmental friendliness, and high specific capacity versus zinc (in excess of 400 mAh/g)1. V2O5 exhibits a single layer crystal structure which provides a large number of theoretical storage sites2. However, charge storage mechanisms and driving force behind the capacity fade in V2O5 are not well known yet. The lack of understanding surrounding insertion and storage mechanisms of zinc ions into V2O5 cathodes must be addressed to progress toward commercial viability.In this study, we aim to conduct in-operando stress and stress measurements in V2O5 during battery cycling. Curvature interferometry and digital image correlation techniques will be employed for in operando stress and strain measurements, respectively the composite V2O5 cathode will consist of a 7:2:1 ratio of active material, super P, and PVDF binder. By combining stress and strain measurements, coupled with spectroscopy studies, our goal is to identify the how interfacial stress and structural strains play a role on the charge storage mechanisms in V2O5.

Evaluating a Dual-Ion Battery with an Antimony-Carbon Composite Anode.

Dual-ion batteries (DIBs) are attracting attention due to their high operating voltage and promise in stationary energy storage applications. Among various anode materials, elements that alloy and dealloy with lithium are assumed to be prospective in bringing higher capacities and increasing the energy density of DIBs. In this work, antimony in the form of a composite with carbon (Sb-C) is evaluated as an anode material for DIB full cells for the first time. The behaviour of graphite||Sb-C cells is assessed in highly concentrated electrolytes in the absence and presence of an electrolyte additive (1 % vinylene carbonate) and in two cell voltage windows (2-4.5 V and 2-4.8 V). Sb-C full cells possess maximum estimated specific energies of 290 Wh/kg (based on electrode masses) and 154 Wh/kg (based on the combined mass of electrodes and active salt). The work expands the knowledge on the operation of DIBs with non-graphitic anodes.

An evaluation of optimal sized second-life electric vehicle batteries improving technical, economic, and environmental effects of hybrid power systems

Electric vehicle (EV) batteries provide energy and power sufficiently until their capacity degradation reaches 80%. Afterward, EV batteries need to remove due to their insufficient power and energy capacity to satisfy the range and speed requirements. Increasing EV sales means numerous second-life batteries (SLB) will be available for second-use applications. Besides the price and capacity differences of SLB, technical properties such as depth of discharge (DOD), temperature, and cycle life will directly affect the performance. This study comprehensively examines SLB feasibility, focusing on the technical and financial uncertainties of SLBs in stationary energy storage applications. In addition, the contribution of SLB to the marginal cost-revenue balance is optimized by considering various operating criteria and four different battery aging sub-models. The remaining capacity and DOD effects were analyzed, and break-even points were determined. Sensitivity analyses also assess the carbon tax and the performance of SLB in different climatic zones. Finally, the accuracy of technical, economic, and environmental performance has been increased with multi-year sensitivity analysis. According to optimal results, SLB could increase energy efficiency up to 14% with 80% capacity and under 80% DOD. It has also been found that if the SLB cost is less than 57% of the fresh battery (FB), the same system will reach the break-even point. Thanks to the carbon tax, SLB reduced discount payback for up to 3 years, increased RF by up to 5%, and improved state of health (SOH) by 13%, giving sustainable environmental and economic results.

Room temperature manufacture of dense NaSICON solid electrolyte films for all-solid-state-sodium batteries

Sodium (Na) Super-Ionic CONductor (NaSICON) solid electrolyte (SE) powders (Na3Zr2Si2PO4) were prepared by the mixed oxide technique using a planetary ball mill and synthesized via solid-state method at temperatures ranging from 950 to 1200 °C. The powders with 95% pure NaSICON phase were deposited on different substrates via Powder Aerosol Deposition (PAD) at room temperature directly from the powders and fully dense ceramic films were obtained. X-ray diffractometry including Rietveld refinement were carried out on both the calcined powders and the resulting films to determine the crystallographic properties. Subsequently, the electrical properties of the resulting films were characterized and the effect of annealing at temperatures between 100 and 600 °C on the ionic conductivity of NaSICON PAD films was evaluated. Annealed films were measured in the temperature range 50 and 250 °C to calculate the activation energy Ea of the PAD films. Our work demonstrates a successful room temperature deposition of dense NaSICON electrolyte films on different substrates, which is promising for stationary energy storage applications of solid-state-sodium batteries.

Non-aqueous organic redox active materials for a bicontinuous microemulsion-based redox flow battery

To mitigate fluctuations in renewable energy sources, redox flow batteries (RFBs) attract much attention for stationary energy storage applications by taking advantage of decoupling power and energy. However, there are still some limitations for conventional RFBs, including low energy density, a narrow electrochemical window (∼1.23 V) for an aqueous electrolyte, and low ionic conductivity for a non-aqueous electrolyte. Herein, we demonstrate a bicontinuous microemulsion-based RFB using methyl-p-benzoquinone and 2,2,6,6-Tetramethyl-1-piperidinyloxy as anolyte and catholyte redox active materials, respectively. By stabilizing an aqueous and organic medium at a nanometer scale through a surfactant, the microemulsion electrolyte exhibits a wider electrochemical window and good ionic conductivity, a promising alternative to increase the energy density by applying non-aqueous redox species with high solubility and high redox potential. The resulting cell exhibits Coulombic efficiency of 80%–85% and capacity retention of 50% over 30 cycles. We provide a systemic analysis of performance limitation and capacity decay and proposed a possible dimerization mechanism for an anolyte through a density functional theorycalculation, ending with a discussion of the efforts needed to realize the application of microemulsion-based RFBs.

Identifying the Synergistic Na+/Zn2+ Co-Intercalation Mechanism for Boosting Electrochemical Performance of Na4Fe3(PO4)2P2O7 in Zn-Ion Batteries

Rechargeable aqueous zinc-ion batteries (ZIBs) have been regarded as a promising battery technology for stationary energy storage applications due to high safety, long-term sustainability, and low cost. The main challenge for ZIBs is the lack of robust structure to accommodate repeated ion insertion/extraction in aqueous solutions. In contrast to transition metal oxides cathodes (MnO2, V2O5), iron-based polyanionic compounds have rigid structure and open framework, hence may serve as compatible cathodes for aqueous batteries. However, only several iron-based polyanionic cathodes such as Na4Fe3(PO4)2P2O7, have received scant attentions to date, not to mention that their underlying complex reaction mechanisms in aqueous solutions have not yet been clearly revealed. In this work, we identify the Na+/Zn2+ cointercalation mechanism of Na4Fe3(PO4)2P2O7 in zinc-ion batteries by both experimental spectra and DFT calculations. Benefiting from the synergistic chemistry, the Na4Fe3(PO4)2P2O7 demonstrates enhanced structural stability and ion diffusion kinetics upon the Na+/Zn2+ cointercalation in comparison with single metal ion (only Na+ or Zn2+) storage reaction, hence a high-power density (6.73 kW kg–1) and long cycle life (54.6% after 5000 cycles) are exhibited. In particular, the prominent reaction kinetics endows the battery with low-temperature (−30 °C) operation capability (capacity retention of 87.6%).

State estimation and aging mechanism of 2nd life lithium-ion batteries: Non-destructive and postmortem combined analysis

Lithium-ion batteries used in electric vehicles (EVs) are expected to reach end-of-life (EoL) after 10–15 years of operation. Consequently, it is urgent to devise repurposing strategies, which may range from recycling to a 2nd life in stationary energy storage applications. In this paper, aiming the 2nd life repurposing of the batteries, the state estimation and aging mechanisms of retired 32,650-type LiFePO4/graphite batteries were studied. The aging state of batteries was evaluated in terms of their capacity, resistance and self-discharge rate. Test results show that there is no strong correlation between battery capacity decay and resistance increase. To identify and quantify the aging mechanisms of the 2nd life batteries after being cycled at different rates (0.5C, 1C and 2C), non-destructive analyses (incremental capacity/differential voltage curves, modified equivalent circuit model, and electrochemical impedance spectroscopy) are combined with postmortem analysis. The results reveal that the aging of the batteries cycled at 0.5C is primarily due to the loss of active material (LAM), while the loss of lithium inventory (LLI) is rather insignificant. For the batteries cycled at 1C and 2C, in addition to LAM, LLI is also severe, eventually leading to an increase in resistance of the battery, which causes a rapid decline of the battery capacity. The results also indicate the non-destructive methods are reliable to identify ongoing aging mechanisms.

Design of Phosphide Anodes Harvesting Superior Sodium Storage: Progress, Challenges, and Perspectives

AbstractSodium (Na) ion batteries (SIBs) are promising in stationary energy storage applications. Research is also afoot to seek suitable electroactive materials for use in SIBs. Recently, phosphides to be used in the anode for Na storage are particularly appealing due to their high specific capacities and low working potentials. The following matters are to deal with their inherent drawbacks of large volume variation and inferior interfacial stability upon Na insertion/extraction, which is believed to be largely responsible for capacity and cycling decay. Despite striking progress in addressing the above drawbacks, current studies on phosphides remain preliminary. In this review, an in‐depth understanding of phosphides regarding Na storage mechanism, capacity assessment, phase change, and reaction types is provided. The effective strategies and the sound designs of phosphides for Na storage are also discussed. Their correlations between electrochemical behavior and chemical/structural characteristics are analyzed, in a bid to sort out the basic ideas for the design of high‐performance phosphides that enable high‐energy and durable SIBs. Doubtless, the experience and knowledge gained from the research on phosphides are shared, and the strategies are expected to extend the scope beyond phosphides.

Cutting-edge research is taking lead batteries to the next level

Cutting-edge research is taking lead batteries to the next level Energy storage is critical to our collective future. At the Consortium for Battery Innovation (CBI), we are committed to ensuring this technology continues to advance by initiating collaborative research projects and setting targets for the whole lead-battery industry. We have developed a detailed technical roadmap to establish targets and drive innovation across several critical global markets–notably automotive, stationary energy storage, motive power, and industrial applications. In this article, we take a foray into some cutting-edge work the CBI and its community are undertaking.

Comparative Analysis of Battery Cycle Life Early Prediction Using Machine Learning Pipeline

Lithium-Ion battery system is one of the most critical but expensive components for both electric vehicles and stationary energy storage applications. In this regard, accurate and reliable early prediction of battery lifetime is important for optimizing life cycle management of batteries from cradle to grave. In particular, accurate aging diagnostics and prognostics is crucial for ensuring longevity, performance, safety, uptime, productivity, and profitability over a battery's lifetime. However, current state-of-art methods do not provide satisfactory prediction performance (lack of uncertainty quantification) using early degradation data. In the present work, to produce the best model for both battery cycle life point prediction and range prediction (i.e., confidence intervals or prediction intervals), a pipeline-based approach is proposed, in which a full 33-feature set is generated manually based on battery degradation knowledge, and then used to learn the best model among five machine learning (ML) models that have been reported in the battery lifetime prediction literature, and two quantile regression models for battery cycle life prediction. The calibration and sharpness property of battery cycle life range prediction is properly evaluated by their coverage probability and width respectively. The experimental results show that the gradient boosting regression tree model provides the best point prediction performance, while the quantile regression forest model provides the best range prediction performance with both full 33-feature set and the MIT 6-feature set.

Advanced Investigation of the Electrolyte-Mg Anode Interphase for the Development of Mg-Ion Batteries

Magnesium-ion batteries (MIBs) represent a promising chemistry to potentially substitute lithium-ion technologies in the e-mobility and stationary energy storage applications. This is due to the favourable properties of metallic Mg, such as: abundancy, non-toxic nature, high recycling rate1, low redox potential (-2.37 vs SHE), safety (smooth Mg2+ electrodeposition), as well as divalent character of Mg2+ cations which leads to higher theoretical volumetric capacity (3833 mAh/cm3) than Li (2046 mAh/cm3) and commercial graphite (760 mAh/cm3).2 However, the major obstacle in the further development of MIBs is the incompatibility of Mg metal anode with conventional electrolyte solutions, which are formed by mixing simple Mg-based salts (e.g Mg(TFSI)2, Mg(ClO4)2, etc.) and polar aprotic solvents (e.g. acetonitrile, carbonates, etc.). These solutions decompose at the surface of metallic Mg forming an electronic and ionic insulating layer, leading to the passivation of the Mg anode and poor performance of the overall cell. Conversely, organoborate (Mg-tetrakis(hexafluorosisopropyloxy)borate in monoglyme, MgBOR)3 or organoaluminate (1:2 AlCl3:PhMgCl in THF, APC)4 ethereal solutions are known to prevent the passivation of the Mg metal anode, allowing the reversible electrochemical Mg2+ electrodeposition onto its surface.Despite a great effort has been done in the development of MIB,5 very little is known about the formation, evolution and degradation of the solid electrolyte interphase (SEI) formed at the interface between metallic Mg and electrolyte. This work, therefore, aims to investigate the interactions between Mg metal and passivating (Mg(TFSI)2 in monoglyme:diglyme) and non-passivating (MgBOR and APC) electrolytes combining ex-situ and in-situ spectroscopic and microscopic techniques with electrochemical testing. The properties of the SEIs will be evaluated at different states of charge (ex-situ) and during cell cycling (in-situ).Raman, Fourier transformed infrared (FTIR) and X-ray photoelectron (XPS) spectroscopies are used to identify the composition of the electrolyte interphases, as well as monitor their changes upon cell discharge-charge cycles. Scanning electron microscopy (SEM) is performed to analyse the interphase morphologies, whereas scanning microwave microscopy (SMM)6,7 locally probes the impedance of the SEI layer. Atomic force microscopy (AFM) is also employed to evaluate the roughness of the Mg metal electrodes. Cyclic voltammetry (CV) and galvanostatic cycling with potential limitation (GCPL) are carried out in order to determine the electrochemical performance of bare Mg metal or covered with SEI layers. Furthermore, electrochemical impedance spectroscopy (EIS) is employed to probe the Mg2+ diffusion coefficients through the SEI layers at different state of charge (e.g. open circuit voltage, etc.) and determine charge transfer evolution with cycling time of the Mg metal anode.As the first step, a successful polishing method was developed to remove the native oxide layer form the surface of Mg discs allowing to expose a bare Mg metal to the electrolyte solutions and to evaluate their interactions. The polishing method also enabled to perform SMM imaging of the Mg metal since a roughness between 1-2.5 µm was achieved. The Mg discs were then immersed in the electrolyte solutions and an initial deposition of interfacial species (few nanometre thickness) was observed by SEM when Mg(TFSI)2 in monoglyme:diglyme was used, whereas a smooth surface was detected with MgBOR and APC electrolytes. This resulted in different electrochemical behaviours. In fact, symmetric cells (Mg||Mg) with MgBOR electrolyte showed a significantly higher cycling stability (> 250 h) than those with Mg(TFSI)2 in monoglyme:diglyme solution. In addition, when the latter electrolyte was used, fluorinated by-products were identified by XPS. In order to study the SEI formation and growth further, in-situ spectroscopic techniques (e.g. Raman and SMM) were employed to establish a correlation between the chemical composition of the electrolyte, the voltage range of the electrochemical tests and cycling time. In particular, the SMM method was applied to MIB technologies for the first time in this work. References I. R. P. United Nations Environment Programme, (available at https://wedocs.unep.org/20.500.11822/8702);J. Niu, Z. Zhang, D. Aurbach, Adv. Energy Mater., 2020, 10, 2000697;Z. Zhao-Karger, M. E. Gil Bardaji, O. Fuhr, M. Fichtner, J. Mater. Chem. A, 2017, 5, 10815–10820;D. Aurbach, Z. Lu, A. Schechter, Y. Gofer, H. Gizbar, R. Turgeman, Y. Cohen, M. Moshkovich, E. Levi, Nature, 2000, 407, 724;R. Dominko, J. Bitenc, R. Berthelot, M. Gauthier, G. Pagot, V. Di Noto, J. Power Sources, 2020, 478, 229027;A. Buchter, J. Hoffmann, A. Delvallée, E. Brinciotti, D. Hapiuk, C. Licitra, K. Louarn, A. Arnoult, G. Almuneau, F. Piquemal, M. Zeier, F. Kienberger, Rev. Sci. Instrum., 2018, 89, 23704;J. Hoffmann, M. Wollensack, M. Zeier, J. Niegemann, H. Huber, F. Kienberger, in 2012 12th IEEE International Conference on Nanotechnology (IEEE-NANO), pp. 1–4.