Increase In Discharge Capacity Research Articles

Microstructural study of sonochemical synthesized belt-like Zr(MoO4)2/MoO3 composites for efficient energy storage

It is currently being widely explored as an electrode material for future storage devices that transition metal oxides can provide a synergistic effect during electrochemical reactions. We synthesized composites of Zr(MoO4)2/MoO3 with belt-like morphologies using ligand assisted Ultrasonics. Compared to other methods of synthesis, ultrasonic synthesis is less costly and easier to use, and it has the advantage of speeding up the formation process. It is possible that the duration of the sonication process can have an impact on the microstructural properties of the sample. As a result, Zr(MoO4)2/MoO3 composites were synthesized under ultrasonic probes for five, ten, and fifteen minutes, respectively. The achieved sample serves as an active material in an electrochemical energy storage system comprised of a three-electrode cell and an electrolyte containing KOH. Depending on the current density, the kinetics of the electrochemical reaction and the stability of the materials in the working electrode are affected. Nevertheless, the capacity of Zr(MoO4)2/MoO3 composites was studied at different currents of 0.5, 1, 2 and 3 mA in order to identify optimal parameters. The results indicate an increase in discharge capacity at 2 mA from the first cycle to the thirteenth cycle, from 200 to 750 mAhg−1. In contrast, applying a current of 3 mA results in a decrease in capacity and structural damage. Conversely, using lower currents of 0.5 and 1 mA results in lower capacity compared to 2 mA. In this way, belt-like Zr(MoO4)2/MoO3 composites can be utilized as potential active materials in energy storage systems, such as hydrogen storage.

Improving the electrochemical performance of ultrahigh-nickel-based layered LiNi0.95Mn0.05O2 cathode through cobalt modification for next-generation high-energy Li-ion batteries

Nickel-rich cobalt-free layered cathode materials are expected to meet the urgent demand for high-energy batteries at an adorable cost. However, as the nickel content increases and cobalt content decreases, layered cathode materials suffer from serious structure degradation and capacity fade during cycling. The large amount of residual lithium in nickel-rich materials also brings difficulties to industrial manufacturing and challenges battery safety. In this work, well-formed crystal cobalt-contained coatings with surface cobalt-doped ultrahigh-nickel-based layered LiNi0.95Mn0.05O2 cathode material is synthesized through solid solution and post-heat treatment with Co(OH)2, during which the residual lithium is significantly consumed. The optimized sample acquired at 650 ℃ shows an increased discharge capacity of 221.2 mAh g−1 from 219 mAh g−1 of the pristine one at 0.1 C and the capacity retention is enhanced from 72.6% to 83.2% for 100 cycles at 0.5 C.

Preparation of nickel and graphene modified La9CeMg80Ni5 composites and their microstructure and electrochemical properties

A La2Mg17-type alloy La9CeMg80Ni5 was prepared and mechanically crushed to powders. Ni and Graphite (GR) were added during ball milling to prepare the surface-modified La9CeMg80Ni5-GR-Ni composites. The influence of milling time and Ni content on the structure and electrochemical properties of the composite materials were investigated. After milling, the composite materials are capable of electrochemically hydriding and dehydriding at room temperature. As Ni content increases, the 40 h-milled composites show an increased discharge capacity from 219.6 to 986.2 mAh/g, HRD from 75.3% to 86.8%, and capacity retention rate of 20th cycle from 58.2% to 65.8%; the 80 h-milled composites show an increased discharge capacity from 252.6 to 1034.7 mAh/g, HRD from 80.5% to 87.9%, and capacity retention rate of 20th cycle from 47.3% to 56.2%.

ErMnO3/Er2Mn2O7/ZnO/GO multi-component nanocomposite as a promising material for hydrogen storage: Facile synthesis and comprehensive investigation of component roles

As part of this work, a multi-component nanocomposite with hydrogen storage capability was synthesized. To begin with, ErMnO3/ErMn2O5/ZnO were synthesized in-situ, and then graphene oxide (GO) was added. Oxygen-containing functional groups on the surface of GO acted as an oxidant, resulting in ErMn2O5 (Mn+3) being converted to Er2Mn2O7 (Mn+4). A secondary phase of ErMn2O5 was formed as a result of calcination temperatures lower than 1200 °C, facilitating the in-situ synthesis of three-component nanocomposite materials. An important aspect of this work is examining each component's role in changing the properties. Moreover, results showed that adding ZnO could change the magnetic property from ferromagnetism to paramagnetism, and thanks to GO, ferromagnetism was revealed once again. An electrochemical test confirmed that ZnO and GO could promote H2-storage capacity, increasing discharge capacity from 450 to 850 mAhg−1 and 1200 mAhg−1 during different steps. It can be considered that an increase in pore volume (about 10 times) is one of the factors contributing to this phenomenon.

The Double-Edged Effect of Water on Li-O2 Aprotic Batteries

Storing larger amounts of energy is becoming critical as more renewable and intermittent energy sources emerge in our society. Li-O2 batteries have the highest theoretical energy density, but there are still barriers to overcome. The presence of water in atmospheric air makes studying its effects on battery performance necessary if ambient oxygen ought to be used in such devices. This paper investigates the effect of different concentrations of water in the electrolyte of Li-O2 aprotic batteries, on deep discharge capacity and cyclability. Batteries were prepared with a metallic lithium anode, glass microfiber membrane, 0.1 M LiClO4/DMSO electrolyte with various water concentrations (15–144,000 ppm), and carbon paper cathode. An increase in discharge capacity of >300% was achieved with 550 ppm of water; however, a gradual reduction in cyclability was observed increasing water concentration. We show that it occurs due to changes in the reaction mechanism, composition, and morphology of the discharge products, incomplete decomposition, and formation of a passivating film on the metallic lithium anode. Moreover, this article elucidates the causes underlying the involved mechanism and highlights the double-edged effect of water on the electrochemical performance of Li-O2 batteries, causing improvements in deep discharge capacity at the cost of reduced cyclability.

Mechanical Structuring of Lithium‐Ion Battery Electrodes Using an Embossing Roller

Highly performing lithium‐ion batteries are essential for the electrification of the transport sector. However, the two performance criteria, high power density and high energy density, inversely correlate with each other via the mass loading of the electrodes. To achieve high charging and discharging rates at high energy densities, structuring of electrodes is a proven method. Currently, structures are mostly realized by laser ablation, which comes along with material loss and low process rates. Herein, a concept for electrode structuring through mechanical embossing in a high‐throughput roll‐to‐roll process is elaborated. Different integration options are described and the challenges are discussed. To provide a proof of concept, a hand‐operated embossing device is built and used to structure graphite anodes. In a rate capability test, an increase in discharge capacity at medium C‐rates by up to 14.3% is observed.

Numerical Study on Hydraulic Characteristics and Discharge Capacity of Modified Piano Key Weir with Various Inlet/Outlet Width Ratio

A modified piano key weir with a rounded nose and a parapet wall (MPKW) can improve the discharge capacity significantly compared to a standard piano key weir. However, the optimum of the inlet/outlet width ratio (Wi/Wo) on the discharge efficiency of MPKW is still not investigated numerically. The present work utilized the numerical modeling to investigate and analyze the effects of the inlet/outlet key width ratios on the hydraulic characteristics and discharge capacity of the MPKW. To validate the numerical model with the experimental data, the results indicate that the average relative error is 2.96%, which confirms that the numerical model is fairly well to predictthe specifications of flow over on the MPKW. Numerical simulation results indicated that the discharge capacity of the MPKW can be improved up to 8.5% by optimizing the Wi/Wo ratio ranging from 1.53 to 1.67 even if the other parameters of the MPKW keep unchanged. A big Wi/Wo ratio generally leads to an increase in discharge capacity at low heads and a little effect on the discharge efficiency at high heads. The discharge efficiency of the inlet and outlet crests increases up to 9.6% for high heads, while discharge efficiency of the lateral crest decreases up to 23.5% compared with the reference model. The findings of the study revealed that the intrinsic influencing mechanism of the Wi/Wo ratio on the discharge performance of MPKWs.

Solution-gel-based surface modification of LiNi0.5Mn1.5O4-δ with amorphous Li-Ti-O coating.

LNMO (LiNi0.5Mn1.5O4-δ) is a high-energy density positive electrode material for lithium ion batteries. Unfortunately, it suffers from capacity loss and impedance rise during cycling due to electrolyte oxidation and electrode/electrolyte interface instabilities at high operating voltages. Here, a solution-gel synthesis route was used to coat 0.5-2.5 μm LNMO particles with amorphous Li-Ti-O (LTO) for improved Li conduction, surface structural stability and cyclability. High-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) analysis coupled with energy dispersive X-ray (EDX) showed Ti-rich amorphous coatings/islands or Ti-rich spinel layers on many of the LTO-modified LNMO facets, with a thickness varying from about 1 to 10 nm. The surface modification in the form of amorphous islands was mostly possible on high-energy crystal facets. Physicochemical observations were used to propose a molecular mechanism for the surface modification, combining insights from metalorganic chemistry with the crystallographic properties of LNMO. The improvements in functional properties were investigated in half cells. The cell impedance increased faster for the bare LNMO compared to amorphous LTO modified LNMO, resulting in Rct values as high as 1247 Ω (after 1000 cycles) for bare LNMO, against 216 Ω for the modified material. At 10C, the modified material boosted a 15% increase in average discharge capacity. The improvements in electrochemical performance were attributed to the increase in electrochemically active surface area, as well as to improved HF-scavenging, resulting in the formation of protective byproducts, generating a more stable interface during prolonged cycling.

LiNi0.5Mn1.5O4 Thin Films Grown by Magnetron Sputtering under Inert Gas Flow Mixtures as High‐Voltage Cathode Materials for Lithium‐Ion Batteries

AbstractDelivering a commercial high‐voltage spinel LiNi0.5Mn1.5O4 (LNMO) cathode electrode for Li‐ion batteries would result in a significant step forward in terms of energy density. However, the structural ordering of the spinel and particle size have considerable effects on the cathode material's cyclability and rate capability, which are crucial challenges to address. Here, a novel mid‐frequency alternating current dual magnetron sputtering method was presented, using different Ar‐N2 gas mixtures ratios for the process gas to prepare various LNMO thin films with highly controlled morphology and particle size; as determined from X‐ray diffraction, Raman spectroscopy and electron microscopy. It resulted in enhanced cycling and rate performance. This processing method delivered N‐containing LNMO thin film electrodes with up to 15 % increased discharge capacity at 1 C (120 mAh g−1) with respect to standard LNMO (grown under only Ar gas flow) thin film electrodes, along with outstanding rate performance up to 10 C (99 mAh g−1) in the operating voltage window 3.5–4.85 V vs. Li+/Li. Besides, electrochemical impedance spectroscopy results showed that the intricate phase transitions present in standard LNMO electrodes were almost suppressed in N‐containing LNMO thin films grown under different Ar‐N2 gas flow mixtures.

Techno-economically feasible beverage can as superior anode in rechargeable Al-air batteries

Porous Fe nitrogen-doped carbon (Fe-NC) with a polyhedron structure, derived from zeolitic imidazolate framework 8 (ZIF8), was synthesized as an efficient electrocatalyst in Al-air batteries, complemented by a low-cost aluminium anode based on beverage cans. The highly-loaded porous Fe-NC demonstrated efficient catalytic activity towards the oxygen reduction reaction (ORR). This was linked to the good conductivity and the large surface area originating from the observed 3D porous architecture. The RDE test confirmed that the favourable 4-electron pathway for porous Fe-NC was higher than that of the 20 wt% Pt/carbon. Besides the high ORR activity, the Al-air battery demonstrated a maximum power density of 46 mW/cm2 at a current density of 80 mA/cm2. The galvanostatic discharge studies showed a stable voltage discharge plateau (>1.1 V) for current densities between 5 and 20 mA/cm2. The Al-air battery with porous Fe/NC catalyst exhibited a remarkably increased discharge capacity of 1920 mAh/g for the pure Al foil and 1173 mAh/g for the commercial Al can foil at a current density of 20 mA/cm2. The finding indicates that both anode and cathode in this work are techno-economically feasible materials. In addition, the Al-air battery showed large charge-discharge cycles (i.e., 180 cycles, 31 h) at 10 mA/cm2 with a low voltage gap using a beverage can.

Enhanced Electrochemical Performance of LiNi1/3Co1/3Mn1/3O2 at a High Cut-Off Voltage of 4.6 V by Li1.3Al0.3Ti1.7(PO4)3 Coating

At present, LiNi1/3Co1/3Mn1/3O2 (NCM) is a widely used material in the commercial market due to the easy control of the preparation process and usage environment. However, its capacity keeps fading when the cut-off voltage increases. In this research, an Li1.3Al0.3Ti1.7(PO4)3 (LATP) coating method is proposed to improve the cycle performance of LiNi1/3Co1/3Mn1/3O2 at a high cut-off voltage of 4.6 V. The battery prepared with LATP-modified NCM exhibits an increased discharge capacity retention of 92.37% after 100 cycles at 0.2C (1C = 200 mA g−1), while the bare NCM only presents 64.28%. Our results indicate that LATP-surface coating might be a useful method to increase the cycle stability of NCM and other high-capacity cathode materials.

Integration of laser structuring into the electrode manufacturing process chain for lithium-ion batteries

Despite the electrochemical benefits of laser electrode structuring, the process is not yet implemented in state-of-the-art industrial battery production due to a limited knowledge regarding its implementation into the manufacturing process chain. In this study, three process integration positions for laser structuring of graphite anodes, which are either after coating, after drying or after calendering, were experimentally evaluated. The obtained electrodes were analyzed regarding geometrical, mechanical and electrochemical characteristics. The results indicate that the material ablation process is governed by the evaporation of solvent and binder for wet and dry electrodes, respectively. As a consequence, electrodes structured in wet condition exhibited fewer particle residues on the electrode surfaces and a high coating adhesion strength. In contrast, laser structuring of dry electrodes significantly reduced the pull-off strengths of the electrode coatings. A tortuosity reduction and an increased discharge capacity at high C-rates by laser structuring were observed for all structured electrodes, but with higher performance improvements for electrodes structured in dry state. Although a partial clogging of the structures was observed in electrodes structured before calendering, laser structuring yielded a comparable electrochemical performance of electrodes which were structured in dry condition before and after calendering.

High temperature electrochemical discharge performance of LaFeO3 coated with C/Ni as anode material for NiMH batteries

Perovskite LaFeO3 is considered as a promising new anode material for nickel/metal hydride batteries due to its low cost, environmental friendliness and high temperature resistance. However, the poor conductivity of LaFeO3 material restricts the discharge ability, which is problematic for its future widespread application. To solve the above issue, in this study, we prepared C/Ni-coated LaFeO3 composite in view of the excellent electrical conductivity of carbon and nickel metal. Results show that the C/Ni-coated LaFeO3 composite delivers remarkably increased discharge capacity of ∼345 mAh g−1 at 60 ​°C in contrast to ∼267 mAh g−1 for pure LaFeO3. Furthermore, the carbon and nickel not only increase the electrical conductivity of the LaFeO3 but also reduces the agglomeration of the LaFeO3, therefore, the C/Ni-coated LaFeO3 composite serves superior long cycle-life, which maintains 60.9% after 100 cycles (52.9% for the LaFeO3 sample). In overall, the electrochemical behavior of the C/Ni-coated LaFeO3 composite confirms its high potential as nickel/metal hydride batteries for energy storage applications.

Graphene-enhanced sulfur cathode with high interface stability in Li-S batteries

The physicochemical properties of graphene and graphene materials obtained by the method of controlled detonation gas synthesis are presented. The fundamental possibility of controlling the graphene and graphene materials physicochemical properties by changing the synthesis conditions is shown. Dynamics of changes in the impedance spectra of Li-S and Li-S-Li batteries with graphene in non-aqueous liquid electrolyte 0.7 M LiIm, 0.25 M LiNO3, DME:DOL (2:1) were studied. The results of electrochemical testing of experimental samples and prototypes of elements of the lithium-sulfur system by the methods of cyclic voltammetry and galvanostatic cycling are presented. The effect of interface stabilization was expressed in a decrease in impedance spectra, an increase in discharge capacity, and more stable long-term cycling with high parameters. The investigation showed a positive effect of graphene materials in the active mass of the multilayered S-based electrode with special design.

Effects of Current and Ambient Temperature on Thermal Response of Lithium Ion Battery

Both operating current and ambient temperature have a great impact on heat generation and the available residual capacity of the lithium ion battery. The thermal response of the lithium ion battery is investigated under isothermal conditions. Six currents from 1 A to 6 A, with a 1 A interval, are investigated in order to discuss the effect of current under 25 °C; four temperatures from 10 °C to 55 °C, with a 15 °C interval, are investigated to study the effect of temperature under the current of 2 A. The heat generation rate increases with the current increasing during both the charge and discharge stage, but the charge capacity remains independent of current, while the discharge capacity decreases with increasing current. Heat generation decreases with increasing temperature in both the charge and discharge stage, while charge capacity and discharge capacity increase. with the temperature increasing from 10 °C to 55 °C. Heat generation of per charge/discharge capacity is also discussed, and in most cases, the heat generation of per charge capacity during the constant voltage charge stage is larger than that during the constant current charge stage. Heat generation increases at the expense of available capacity, during the discharge stage.

Benefits of Tuned Binder Distribution in Multi-Layered Thick NMC811 Cathodes

Maximizing the electrode thickness is an inevitable target to reach when improving the energy density of Li-ion batteries [1,2]. Unfortunately, the fabrication of electrodes of several hundreds of micrometer thickness is often accompanied by detrimental side-effects. A critical process step in thick electrode production is the drying of the coated layer. During the evaporation of the solvent, light components of the slurry such as binder and carbon black can be dragged to the top of the coating [3,4]. The lack of liquid linkage throughout the layer leads to binder particles being evenly spread across the coating after the drying process is concluded. Inhomogeneous distribution of binder can not only cause delamination, but also negatively influences the Li-ion transport pathways through the electrode. To ensure ideal mechanical stability and satisfactory electrochemical performance, binder migration needs to be suppressed effectively.Multi-layering has proven itself as a technique within aqueous processing to overcome the limitations arising for thick electrodes. Subsequent coating of layers offers opportunities to establish selective material compositions at specific regions within the electrode (Figure 1a). This novel coating method can be considered a steppingstone to further optimize high loading electrodes. We have previously demonstrated that by multi-layering an increase of 40% in adhesion can be achieved compared to single-layer electrodes. Moreover, the assembled cells show superior performances at rate capability tests. Especially for low current densities (0.2C) an increase of up to 20% in specific discharge capacity was reached through multi-layering (Figure 1b) [5].Within aqueous electrode fabrication, the use of sodium carboxy-methyl cellulose (CMC) as binder material is common, due to its role as a thickening agent of the slurry and solubility in water. However, due to its brittleness, the usage of CMC requires additional binders to maintain flexibility of the coating. The ratio of active and inactive materials within the cell is strongly correlated to its capacity and the addition of these binders ultimately results in a decreased energy density of the cell. Besides keeping the particles together, the main purpose of the binder is to guarantee good adhesion to the substrate. Therefore, a high concentration is not necessarily needed at the top of the coating and the overall amount of binder material should be kept at a minimum.Bi-layered cathodes consisting of Ni-rich lithium nickel manganese cobalt oxides (NMC811) as active material were fabricated. The concentration of poly(methyl)acrylate (PMA) binder was changed in the top layer and its effect on structural properties and electrochemical performance was investigated. Water-based processed cathodes with high loadings of more than 8 mAhcm-2 were tested in full cell configurations.Reduction of the binder content leads to an increase in specific discharge capacity of up to 40% compared to single-layered and 25% to unmodified multi-layered electrodes at a C-rate of 1C (Figure 1b). Acknowledgements This work was financially supported by the Austrian Federal Ministry for Climate Action, Environment, Energy, Mobility, Innovation and Technology (bmk).[1] Z. Du, D.L.W. Iii, C.D.S. Kalnaus, J. Li, Understanding limiting factors in thick electrode performance as applied to high energy density Li-ion batteries, J. Appl. Electrochem. 47 (2017) 405–415. https://doi.org/10.1007/s10800-017-1047-4.[2] Y. Kuang, C. Chen, D. Kirsch, L. Hu, Thick Electrode Batteries: Principles, Opportunities, and Challenges, Adv. Energy Mater. 9 (2019). https://doi.org/10.1002/aenm.201901457.[3] F. Font, B. Protas, G. Richardson, J.M. Foster, Binder migration during drying of lithium-ion battery electrodes: Modelling and comparison to experiment, J. Power Sources. 393 (2018) 177–185. https://doi.org/10.1016/j.jpowsour.2018.04.097.[4] M. Müller, L. Pfaffmann, S. Jaiser, M. Baunach, V. Trouillet, F. Scheiba, P. Scharfer, W. Schabel, W. Bauer, Investigation of binder distribution in graphite anodes for lithium-ion batteries, J. Power Sources. 340 (2017) 1–5. https://doi.org/10.1016/j.jpowsour.2016.11.051.[5] L. Neidhart, K. Fröhlich, N. Eshraghi, D. Cupid, F. Winter, M. Jahn, Aqueous Manufacturing of Defect-Free Thick Multi-Layer NMC811 Electrodes, Nanomaterials. 12 (2022) 1–15. https://doi.org/10.3390/nano12030317. Figure 1

Control of side reactions using LiNbO3 mixed/doped solid electrolyte for enhanced sulfide-based all-solid-state batteries

Control of side reactions is a critical issue for obtaining all-solid-state lithium batteries (ASSLBs) with comparable performance to lithium-ion batteries (LIBs). In particular, the interfacial reaction at the cathode/sulfide electrolyte interface and decomposition of the sulfide electrolyte lead to a significant deterioration in the electrochemical performance of ASSLBs. Surface-coated cathodes have been used in ASSLBs to mitigate these side reactions. However, the generally used LiNbO3 coating, a representative coating for ASSLBs, is expensive because of the high price of the source materials, and perfect coverage of the entire cathode surface by coating is practically very difficult. In this study, we introduced a LiNbO3 mixed/doped Li6PS5Cl solid electrolyte, instead of surface coating on the cathodes, to improve the resistance against side reactions concerning the sulfide electrolyte. The source material used for LiNbO3 mixing/doping is cheaper than that used for LiNbO3 coating. Partial doping of LiNbO3 was confirmed by laser Raman spectroscopy and field-emission scanning electron microscopy with energy dispersive X-ray spectroscopy (EDS) analysis. An optimum LiNbO3 mixed/doped electrolyte (4 mol.% of electrolyte) showed enhanced ionic conductivity than that of Li6PS5Cl solid electrolyte without LiNbO3. Moreover, the interfacial reaction at the cathode/electrolyte interface and the sulfide electrolyte decomposition were decreased owing to the LiNbO3 mixing/doping effect. The suppression of ion exchange between the cathode and electrolyte was also confirmed by the scanning transmission electron microscopy - energy dispersive X-ray spectroscopy (STEM-EDS) line profile. These results contributed to the increased discharge capacity and improved rate capability of the cell using 96LPSCl-4LNO (4 mol.% LiNbO3 mixing/doping), compared to those of the cell using pristine Li6PS5Cl.

Novel active management of compressive pressure on a lithium-ion battery using a phase transition actuator

This study proposes a novel method for managing the compressive pressure imposed on a lithium-ion battery (LIB) using a phase transition actuator under constrained conditions considering the influence of compressive pressure on the performance and lifespan of LIBs. Specifically, an active pressure management strategy is proposed to maintain the optimal pressure and reduce the equivalent impedance during operation. A closed-loop control scheme is used to maintain compressive pressure via a phase transition actuator considering the dynamic characteristics of the actuator. This configuration allows managing both reversible pressure due to phase transitions at lithium intercalation/deintercalation and irreversible pressure evolution due to solid–electrolyte interface formation and growth. The analysis on experiments indicates that the equivalent impedance and capacity can be managed through active pressure management under stationary and stochastic operational conditions, demonstrating the effectiveness of the proposed method. Specifically, the accumulated stress in an LIB caused by pressure variation is reduced by 56.17% under a stochastic load condition when activating the proposed pressure management strategy, resulting in a 1.47% increase in discharge capacity immediately after operation compared to that under a passive pressurized condition. The proposed method is simple, effective, and economically feasible for battery management systems in terms of compression pressure control.

A Two-Dimensional Transient Model to Investigate the Influence of Flow Field Design on Zinc Deposition and Performance in a Zinc-Iodide Flow Battery

Zinc-based flow batteries are attractive because they have high aqueous solubility and hence high energy density, as well as rapid kinetics [1,2]. Among the aqueous redox flow batteries (RFBs), the zinc-iodide flow battery has been reported to have very high discharge energy density [1]. However, aqueous zinc batteries suffer from dendrite formation resulting in capacity fading and a decreased battery performance. In our previous study [3], we evaluated a novel flow field design for the zinc-iodide flow battery. When compared to a conventional flow-by (FB) mode, significantly higher charge and energy efficiencies were obtained with the novel arrangement. In the novel flow design, part of the was drawn through the porous electrode towards the current feeder, and this was found to enhance the effective surface area and decrease the ohmic loss. This design, called flow-by-through (FBT), with a component of flow in the direction of the current feeder, can prevent the blockage of the mass/ion transport pathway and enhance the flow distribution in hybrid flow batteries [4]. Based on X-ray computed tomography and SEM characterization, a denser zinc deposit, with more zinc deposition inside the felt were observed with the FBT mode, which may explain the increased discharge capacity and cycle life of the battery [3].A mathematical model of the zinc-iodide RFB can help us better understand the battery performance in the different flow modes. Models of RFBs have been used to investigate the impact of the flow field on performance since 1980 [5]. In this study, we have used a two-dimensional transient model with the COMSOL multi-physics software package to study the galvanostatic charge/discharge behavior of the zinc-iodide RFB in FB and FBT modes. The model considers the electrochemical kinetics, mass transport and the current and potential distribution in a single cell zinc-iodide flow battery. This is the first reported modeling study of the influence of the FBT design on the performance of an RFB.The galvanostatic charge-discharge of a zinc-iodide battery was modelled at a current density of 20 mA cm-2, and a charge duration of 20000 s, corresponding to a state of charge of 25.7%. These conditions were chosen to enable comparison and validation with experimental data are shown in Figure 1. The rate of zinc ion consumption and the amount of zinc deposition on the graphite felt electrode for both FB and FBT arrangements were evaluated using the model. The distribution of zinc deposition, potential and current, will be presented, which provide new insights into the impact of the flow arrangement on the battery performance. The model will be applied to predict cell voltage and efficiency, maximum discharge capacity and maximum discharge power density of the zinc-iodide RFB for FB and FBT arrangements.[1] Li, B., Nie, Z., Vijayakumar, M., Li, G., Liu, J., Sprenkle, V., & Wang, W. (2015). Ambipolar zinc-polyiodide electrolyte for a high-energy density aqueous redox flow battery. Nature communications, 6(1), 1-8.[2] Higashi, S., Lee, S. W., Lee, J. S., Takechi, K., & Cui, Y. (2016). Avoiding short circuits from zinc metal dendrites in anode by backside-plating configuration. Nature communications, 7(1), 1-6.[3] ShakeriHosseinabad, F., Daemi, S. R., Momodu, D., Brett, D. J., Shearing, P. R., & Roberts, E. P. (2021). Influence of Flow Field Design on Zinc Deposition and Performance in a Zinc-Iodide Flow Battery. ACS Applied Materials & Interfaces, 13(35), 41563-41572.[4] Zhou, X., Lin, L., Lv, Y., Zhang, X., Fan, L., & Wu, Q. (2020). Elucidating effects of component materials and flow fields on Sn–Fe hybrid flow battery performance. Journal of Power Sources, 450, 227613.[5] Trainham, J. A., & Newman, J. (1981). A comparison between flow-through and flow-by porous electrodes for redox energy storage. Electrochimica Acta, 26(4), 455-469. Figure 1

The potential application of exfoliated MoS2 to aqueous lithium-ion batteries

Cost-effective storage remains one of the greatest challenges facing the adoption of renewable energy generation. Herein we present a cost-effective aqueous rechargeable battery based on MoS2. Increased discharge capacities are achieved by liquid-phase exfoliation, resulting in a 105% increase in capacity and prolonged lithiation plateau. Contributing evidence is provided by High Resolution TEM investigation of the expanded van der Waals gap between adjacent MoS2 layers and particle active surface area. Exfoliated MoS2 and a MoS2/graphite composite cathode is also investigated, resulting in an increase of reversible lithiation levels over 3x that of the base exfoliated material. The preservation of discharge capacities and voltages indicates the composite is highly effective in improving reversible lithiation. Further examination of the cost-effectiveness of the composite reveals vastly superior storage-to-cost ratios relative to other ARB cathodes.