Intercalation Cathode Research Articles

Revealing the Role of Ruthenium on the Performance of P2-Type Na0.67Mn1-xRuxO2 Cathodes for Na-Ion Full-Cells.

Herein, P2-type layered manganese and ruthenium oxide is synthesized as an outstanding intercalation cathode material for high-energy density Na-ion batteries (NIBs). P2-type sodium deficient transition metal oxide structure, Na0.67Mn1-xRuxO2 cathodes where x varied between 0.05 and 0.5 are fabricated. The partially substituted main phase where x = 0.4 exhibits the best electrochemical performance with a discharge capacity of ≈170mAhg-1. The in situ X-ray Absorption Spectroscopy (XAS) and time-resolved X-ray Diffraction (TR-XRD) measurements are performed to elucidate the neighborhood of the local structure and lattice parameters during cycling. X-ray photoelectron spectroscopy (XPS) revealed the oxygen-rich structure when Ru is introduced. Density of States (DOS) calculations revealed the Fermi-Level bandgap increases when Ru is doped, which enhances the electronic conductivity of the cathode. Furthermore, magnetization calculations revealed the presence of stronger Ru─O bonds and the stabilizing effect of Ru-doping on MnO6 octahedra. The results of Time-of-flight secondary-ion mass spectroscopy (TOF-SIMS) revealed that the Ru-doped sample has more sodium and oxygenated-based species on the surface, while the inner layers mainly contain Ru-O and Mn-O species. The full cell study demonstrated the outstanding capacity retention where the cell maintained 70% of its initial capacity at 1C-rate after 500 cycles.

Introducing a new model for solid-state batteries: Parameter estimation and sensitivity analysis on diffusion, concentration, and electrochemical kinetics

Despite their potential, solid-state batteries (SSBs) are challenging to optimize due to the complexity of their materials and the early stage of their modeling, especially compared to liquid-electrolyte technologies. Many existing models rely on empirical equations that cannot represent internal mass-transport and kinetic phenomena. Even studies based on mechanistic models often focus on theoretical explanations of experimental phenomena or generating hard-to-obtain experimental data. In this work, a simple yet versatile mechanistic model – able to simulate any battery composed of a metallic anode, solid electrolyte and intercalation cathode – is proposed and used in a parameter estimation routine to identify the material properties of a Li/LiPON/LiCoO2 battery. After validation, a parametric study is made to address how each material property impacts concentration profiles, discharge curves, overpotentials, and core key-performance indexes (KPIs) related to energy efficiency and battery capacity. Findings reveal that cathode diffusion is critical to enhancing Extraction Efficiency, in some cases reaching 98.9% of the theoretical capacity without enhancing any other parameter. In the case of Energy Efficiency being a priority over capacity, electrolyte diffusion and concentration showed a pivotal role, in the range of parameters studied, to increase Voltaic Efficiency up to 97.8%. Despite not directly affecting the Extraction Efficiency, it is discussed how high overpotentials caused by Electrolyte Concentration and Kinetic Constants still can harm battery capacity, for charge–discharge cycles limited by boundaries in electrical potential. Finally, studies simultaneously varying two or more parameters show that, despite extreme property enhancements (up to ca 500x higher than the standard case) indeed lead to exceptional results (up to 96.4% for Voltaic Efficiency and 98.9% for Extraction Efficiency), to use such materials at its full potential will result in other zones of the device usually neglected – such as the overpotentials from the metal anode or even the current collector – may become the new stumbling block, underscoring the significance of considering the battery as a holistic system that will inherently exhibit bottlenecks. This also implies, however, in the perpetual potential for enhancement across its components.

Competition for Ion Intercalation in Prussian Blue Analogues as Cathode Materials for Calcium Ion Batteries

With multivalent ion batteries being considered viable post‐lithium energy storage technologies, the last few years have seen increasing interest in intercalation type cathode materials for Ca‐ion batteries (CIBs). Prussian blue analogues (PBAs) display many positive attributes such as open structural framework, large interstitial sites, and versatile transition metal redox activity. The PBA cathodes reported for CIBs often contain K‐ion or Na‐ion due to the syntheses involving the use of potassium or sodium hexacyanoferrate. It has been long overlooked whether the presence of K‐ion or Na‐ion in pristine PBAs could affect the Ca‐ion storage in the PBAs when assessing their CIB performance. Through a combined experimental and computational investigation, this work reports that when K+/Na+ is present in the pristine PBAs, K/Na intercalation is preferred by the PBA structure over Ca intercalation even in the Ca cells. Ca‐ion intercalation can be increased when the K+/Na+ content in the pristine PBAs is reduced, shifting from a K or Na‐dominated intercalation process to a Ca/K or Ca/Na co‐intercalation process. This work consolidates that PBAs are an interesting and versatile intercalation host for several ions, but investigating PBAs as intercalation cathodes requires careful consideration of all ions present in the battery system.

Efficient Zn-Ion Pouch Cell Assembling Based on Aramid Nanofiber Hydrogel

With the fast advancement of portable and wearable electronics, it is urgent to develop safe, stable and flexible power supply devices. Safe and environmentally friendly aqueous zinc-ion batteries (AZIBs) have a low-cost and are perfect candidates for energy storage device in such applications [1-4]. Giving the general challenges, such as the formation of the dendrites on the Zn anodes and hydrogen evolution and side reactions, extensive and wide research has focused on building stable AZIBs with high performance, but less attention was paid to making Zn ion pouch cells which are flexible and with high capacity In this presentation, we developed an efficient method to assemble Zn-ion pouch cells based on the process of formation of the aramid nanofiber hydrogel. The method involves the dipping precursor solution, solvent exchanging, and in-situ electrodeposition of MnO2. The assembled Zn-ion pouch cells exhibit excellent mechanical performance, flexibility and electrochemical performance, which are ideal for portable and wearable electronics. Based on this method, we successfully assembled 3-layer (cathode/anode/cathode, A/C/A) and 5 layer (A/C/A/C/A) pouch cells with over 100 times higher capacity compared with coin cell. In addition, the pouch cell with aramid nanofiber hydrogel and in-situ electrodeposited MnO2 cathode on carbon nanotube mat demonstrates superior cycling stability [5,6]. More details about our assembling method for flexible and stable pouch cells for AZIBs and experimental measurements related to the cycling and stability characteristics, will be presented at the meeting.[1] Yu, Peng, et al. "Flexible Zn‐ion batteries: recent progresses and challenges." Small 15.7 (2019): 1804760.[2] Li, Yingbo, et al. "Recent advances in flexible zinc‐based rechargeable batteries." Advanced Energy Materials 9.1 (2019): 1802605.[3] Li, Chunyang, et al. "High-rate and high-voltage aqueous rechargeable zinc ammonium hybrid battery from selective cation intercalation cathode." ACS Applied Energy Materials 2.10 (2019): 6984-6989.[4] Yu, Feng, et al. "Aqueous alkaline–acid hybrid electrolyte for zinc-bromine battery with 3V voltage window." Energy Storage Materials 19 (2019): 56-61.[5] Wang, Peng, and Petru Andrei. "High Performance Separator and Hydrogel Based on Aramid Fibers for Zn Ion Batteries." Electrochemical Society Meeting s 242. No. 4. The Electrochemical Society, Inc., 2022.[6] Xu, Lizhi, et al. "Water‐rich biomimetic composites with abiotic self‐organizing nanofiber network." Advanced Materials 30.1 (2018): 1703343.

Li-Ion Intercalating Cathode for Advanced Lithium-Sulfur Batteries

The advancement of lithium-sulfur (Li-S) batteries represents a significant shift in high-energy-density electrochemical storage, offering energy densities far exceeding those of traditional lithium-ion systems. This research contributes to the evolving field of Li-S batteries by proposing a novel strategy to optimize cathode performance, crucial in harnessing their full potential.Li-S batteries are characterized by their unique electrochemical process, which involves converting elemental sulfur to lithium sulfide (Li2S) during discharge via lithium polysulfide intermediates. A traditional challenge in this process is the notorious shuttle effect caused by lithium polysulfide intermediates. These intermediates, highly soluble in standard electrolytes, migrate continuously between the cathode and anode, leading to substantial active material loss, rapid capacity degradation, and reduced coulombic efficiency. Significant advancements have been made by introducing metal compounds with a chemical affinity for lithium polysulfides. However, a persistent challenge remains: the insulating nature of Li2S, which hinders electron transport. Recent strategies aiming to address these issues have focused on electrolytes with enhanced Li2S solubility to promote three-dimensional (3D) Li2S growth and prevent cathode passivation. Yet, the increased reactivity of such electrolytes poses new challenges, highlighting the need for alternative solutions.Our study explores this challenge, utilizing lithiated metal oxides as intercalating cathode materials to control Li2S growth dynamics. This method offers immediate mitigation of side reactions in the implementation of enhanced electrolytes. The scope of our research encompasses the thorough synthesis and characterization of these intercalating oxides, emphasizing their role in control Li2S growth. Additionally, we delve into the electrochemical characterization of these materials, focusing on their lithiation/delithiation kinetics and the consequent impact on Li-S battery performance. These intercalating oxides, capable of incorporating lithium ions within their crystal structure, present a promising path for aligning lithiation with Li2S formation, thereby fostering effective 3D growth. This contrasts with other oxides where asynchronous lithiation results in conventional two-dimensional (2D) Li2S growth, leading to premature discharge termination and suboptimal battery performance.We introduce a mechanism where 3D Li2S growth is driven by enhanced solvation of Li2S, intricately linked to the lithiation behavior of these oxides. By incorporating these optimized intercalating oxides in Li-S cells, we observe notable improvements in discharge capacity and sulfur utilization. This improvement is especially significant under high sulfur loading conditions, which typically exacerbate the polysulfide shuttle effect and pose formidable challenges for Li-S battery efficiency. Our investigation includes a detailed morphological analysis of Li2S deposition on various cathode surfaces. Employing advanced techniques like ex-situ Scanning Electron Microscopy (SEM) and electrodeposition modeling, we discern distinct Li2S growth patterns. These findings reveal that cathodes incorporating specific intercalating oxides exhibit reduced surface passivation due to predominant 3D Li2S growth, as opposed to the 2D growth observed in other oxide substrates. This variation in growth morphology significantly impacts cell performance, particularly under high sulfur loading conditions, where effective management of Li2S formation and polysulfide shuttling is crucial.In conclusion, this research marks a significant step in addressing the fundamental challenges of Li-S batteries. By leveraging the distinct properties of select intercalating oxides, the study not only deepens our understanding of Li2S growth mechanisms but also demonstrates an effective method to enhance Li-S battery performance. This work lays a foundation for future developments in high-energy-density battery technologies and signifies a crucial advancement towards the realization of more efficient and robust Li-S batteries.

(Invited) Development of Mildly Acidic Aqueous Zinc Batteries: Anode, Cathode, and Electrolyte

Aqueous zinc batteries use earth abundant materials and has stable supply chains, making them one of the promising battery technologies for grid-scale energy storage applications. However, the limited cycle life because of the dendrite formation of zinc anodes, poor reversibility of cathodes, and consumption of electrolyte has greatly hampered its practical application. Recently, extensive research effort has been made on the development of rechargeable alkaline batteries and mildly acidic zinc ion batteries. Novel structured zinc anodes, intercalation cathode materials and new electrolytes have been developed to improve the performance. Here, we would like to present our effort towards aqueous zinc batteries under practical conditions. Zinc alloy anodes, organic cathode materials, and the use of new binders and electrolyte additives will be discussed.

Influence of the temperature-induced ordered-disordered phases for iron difluoride on the electrochemical performance

Iron difluoride (FeF2) is one of the promising cathodes to achieve high energy-density lithium-ion batteries (LIBs). However, the sluggish ion transportation kinetics in the FeF2 bulk phase may cause large voltage hysteresis and lower cell efficiency, which hinders its commercial adoption. Introducing a disordered phase into the ordered bulk FeF2 is proposed to promote ion transportation and increase ion diffusion channels. Here, varying ratios of the disordered phase are incorporated into the ordered matrix of FeF2 by adjusting the annealed temperatures. The ion transportation is improved due to the optimal ratio of the disordered to ordered (RDO) phase. Among four electrodes, the RDO25% electrode demonstrates the least electrochemical polarization of 1.22 V and the lowest voltage hysteresis of about 1.0 V, in addition to delivering a discharge capacity of 128 mAh g−1 after 100 cycles in the carbonate-type electrolyte. The introduction of the disordered phase enables FeF2 to exhibit a distinct intercalation and conversion dual-mechanism cathode. Additionally, appropriate ratios of the disordered-ordered phase can mitigate nanoparticle agglomeration, establish a conformal cathode electrolyte interface (CEI), reduce interfacial resistance, and thereby enhance ion transport.

Advanced Ether‐Based Electrolytes for Lithium‐ion Batteries

AbstractLithium‐ion batteries (LIBs) have emerged as vital elements of energy storage systems permeating every facet of modern living, particularly in portable electronic devices and electric vehicles. However, with the sustained economic and social development, new‐generation LIBs with high energy density, wide operating temperature range, fast charge, and high safety are eagerly expected, while conventional ethylene carbonate (EC)‐based carbonate electrolytes fail to satisfy corresponding requirements. Comparatively, ether‐based electrolyte systems with fascinating properties have recently been revived in LIBs fields, and many advanced LIBs with exciting performances under ether‐based electrolytes have been developed. This review provides an extensive overview of the latest breakthroughs concerning ether‐based electrolytes applied in LIBs with intercalation cathodes. To systematically outline the progression of ether‐based electrolytes, this review is categorized from the perspective of anodes as follows: i) graphite anode‐based LIBs; ii) silicon anode‐based LIBs; iii) lithium metal anode‐based LIBs.

Bi2S3 for aqueous copper ion battery based intercalation chemistry

Aqueous multivalent ion batteries have attracted increasing attention due to their high capacity, long cycle life, and impressive output energy. Considering that intercalation electrodes are more suitable for long cycle battery compared to the conversion ones, Cu2+ with appropriate ion radii has been chosen as intercalation carriers and bismuth sulfide with the matched lattice spacing as cathode to achieve long cycle life aqueous battery. We have synthesized the micrometer-scale flower-like Bi2S3 by regulating temperature and it is proved to be a perennial phase during Cu2+ intercalation/deintercalation of the Bi2S3 host when charge/discharge with a capacity of 104.5 mAh g–1 retention at 0.5 A g–1 after 1000 cycles. Lastly, build a hybrid ion battery with Zn and ZnSO4 electrolyte, the Bi2S3 cathode for Cu2+ intercalation can reach a maximum energy of 427.5 Wh Kg–1. The study provides a new intercalation cathode for aqueous multivalent ion batteries and will broaden the energy storage system.

Dual–ion symmetric hybrid supercapacitor built by vanadium oxide with expanded interlayers: The intercalation of cation–anion pair and reversible redox of anion excited by Al3+

The development of aluminum ion batteries (AIBs) is retarded by the low capacity of intercalation cathode and ineffective aluminum dissolution/deposition at Al anode. To solve the issues, benzoquinone(BQ)–preinserted hydrated vanadium oxide formulated as (BQ)0.04V2O5·0.87H2O (BQ-VO) with a large interlayer spacing of 13.3 Å was synthesized, which was used as both cathode and anode with Al(ClO4)3 acetonitrile (AN) electrolyte to fabricate a symmetric aluminum–ion supercapacitor. BQ-VO delivers a large capacity of ~152 mAh g−1 at 0.2 A g−1 in the range of 0–1.5 V, which is associated with the intercalation of ion (such as ClO4−, Al3+ or Al3+ − ClO4− pair) into BQ-VO and the reversible redox reaction of ClO4− ↔ Cl−, giving rise to a novel symmetric dual–ion hybrid supercapacitor. The reversible conversion of ClO4− ↔ Cl− is not observed in NaClO4 AN electrolyte, which is only excited by Al3+, leading to a continuous increasing capacity in the early stage of the cycling test. On the contrary, in the NaClO4 AN electrolyte, BQ-VO illustrates a surface-controlled capacitive performance with excellent cycling stability. Molecular dynamic (MD) simulations reveal that Al3+ and Na+ possess different solvation/anion sheaths, leading to different electrochemical performances of BQ-VO in the Al(ClO4)3 and NaClO4 electrolytes. The present work provides a routine to utilize the redox reaction of halide for energy storage.

First-Principles and Experimental Investigation of ABO4 Zircons as Calcium Intercalation Cathodes.

Identifying next-generation batteries with multivalent ions, such as Ca2+ is an active area of research to meet the increasing demand for large-scale, renewable energy storage solutions. Despite the promise of higher energy densities with multivalent batteries, one of their main challenges is addressing the sluggish kinetics in cathodes that arise from stronger electrostatic interactions between the multivalent ion and host lattice. In this paper, zircons are theoretically and experimentally evaluated as Ca cathodes. A migration barrier as low as 113 meV is computationally found in YVO4, which is the lowest Ca2+ barrier reported to date. Low barriers are confirmed across 18 zircon compositions, which are related to the low coordination change and reduced interstitial site preference of Ca2+ along the diffusion pathway. Among the four materials (BiVO4, YVO4, EuCrO4, and YCrO4) that were synthesized, characterized, and electrochemically cycled, the highest initial capacity of 81 mA h/g and the most reversible capacity of 65 mA h/g were achieved in YVO4 and BiVO4, respectively. Despite the facile migration of multivalent ions in zircons, density functional theory predictions of the unstable, discharged structures at higher Ca2+ concentrations (Cax>0.25ABO4), the low dimensionality of the migration pathway, and the defect analysis of the B site atom can rationalize the limited intercalation observed upon electrochemical cycling.

Potential Co2+ and Ni2+ intercalation into nickel hexacyanoferrate in aqueous media: Study of electrochemical process and multivalent batteries implications

Alternative energy storage systems to lithium-ion batteries that can reduce the dependency on such technology have attracted great interest in recent years. Besides their current limitations, multivalent batteries based on coupling a metallic anode (Mg, Zn, Ca…) with a multivalent intercalation cathode are considered as a potential option. Prussian Blue Analogues (PBAs) have shown promising multivalent intercalation capacities and have also been employed in other scientific fields like wastewater treatment, selective element extraction, and may have a potential applicability in batteries recycling. However, some controversies have recently appeared around the capacity of PBAs to incorporate multivalent cations in aqueous media. In this work, we analyze by a combinatorial approach using structural and electrochemical techniques the potential Ni2+ and Co2+ intercalation in K0.61Ni[Fe(CN)6]0.84□0.16·2·12H2O, its limitations, the role of proton intercalation and the cation released after oxidation, which differed from the intercalated during previous reduction step. The potential implications of such findings in current uses of PBAs for multivalent batteries are also discussed.

Boosting the capacity and stability of Na3V2(PO4)2F3-2xO2x microspheres, using atomic layer deposition of artificial CEI

Phosphate-based materials [e.g. Na3V2(PO4)2F3-2xO2x; (NVPFO2x;0 < x < 1)] are regarded as a promising intercalation cathodes for Sodium-ion batteries (SIBs) due to their high reversible specific capacity and stability. However, so far only 2 Na ion were demonstrated to be active in these polyanionic cathodes, which limit their capacity. Herein we provide a strategic approach towards electrochemical activation of a 3rd Na ion, which leads to higher capacity, and preserves structural integrity. We synthesize and study a series of NVPFO2x (0 < x < 1) with well-controlled surface morphology and vanadium oxidation state, and study the dependence of the electrochemical behavior on the various composition and morphology. The optimized NVPFO cathode exhibited highest initial specific discharge capacity (131 mA h g−1) indicating the activation of 3rd Na ion. Nevertheless, the material suffers rapid capacity fading within ~50 cycles. We demonstrate how this instability is suppressed profoundly through the formation of a thin artificial cathode electrolyte interface (CEI) layer of TiO2 (ca. 2 nm) on the surface of NVPFO by atomic layer deposition (ALD). This TiO2 coating enabled even further extraction of sodium through higher voltage domain, but more importantly, it facilitated excellent long-term stability over 200 cycles. The structural stability of the cathode material was revealed by post cycling HRSEM, XPS, and XRD study. All these studies demonstrate that the thin TiO2 layer effectively contributes to formation of a robust CEI layer, diminishes the parasitic reaction on the electrode surface, reduces carbonate formation, and restricts the electrolyte decomposition.

Electrical Double Layer Formation at Intercalation Cathode–Organic Electrolyte Interfaces During Initial Lithium‐Ion Battery Reactions (Adv. Mater. Interfaces 5/2024)

Electrical Double Layer Formation at Intercalation Cathode–Organic Electrolyte Interfaces During Initial Lithium‐Ion Battery Reactions (Adv. Mater. Interfaces 5/2024)

KxVPO4F (x∼0): A New High‐Voltage and Low‐Stain Cathode Material for Ultrastable Calcium Rechargeable Batteries

AbstractThe utilization of high‐voltage intercalation cathodes in calcium‐ion batteries (CIBs) is impeded by the substantial size and divalent character of Ca2+ ions, which result in pronounced volume alterations and sluggish ion mobility, consequently causing inferior reversibility and low energy/power densities. To tackle these issues, polyanionic K‐vacant KxVPO4F (x∼0, designated as K0VPF) is proposed as high‐voltage and ultra‐stable cathode material in CIBs. The K0VPF demonstrates a decent calcium storage capacity of 75 mAh g−1 at 10 mA g−1 and remarkable capacity retention of 84.2% over 1000 cycles. The average working voltage of the K0VPF is 3.85 V versus Ca2+/Ca, representing the highest value reported for CIB cathodes to date. The combined experimental and theoretical investigations revealed that the low volume changes and hopping diffusion barriers contribute to the extraordinary stability and high‐power capabilities, respectively, of K0VPF. The distribution of Ca ions into polyanionic frameworks with pronounced spatial separation effectively attenuates the Ca2+–Ca2+ repulsive force and thus augmenting the Ca migration kinetics. The high voltage of K0VPF is attributed to the inductive effect from the largely electronegative fluorine. In conjunction with a calcium metal anode and a compatible electrolyte, Ca metal full cells featured a record‐high energy density of ≈300 Wh kg−1.

Structure-Controlled Prussian Blue Analog as a Cathode Material for Long-Life Seawater Batteries

Nowadays, as the use of fossil fuels is suppressed for achieving carbon neutrality, rechargeable battery is considered as a key factor to lead sustainable society. As far, the most developed and already commercialized batteries are lithium-ion batteries (LIBs). However, as the demand for LIBs is increasing, there are also several issues in the process of obtaining high-performance batteries. First, as the price of raw materials in LIB rises rapidly, a cost issue arises. In addition, as the fire accidents have occurred consistently due to overcharging or use of organic electrolyte, safety concerns are being raised. Finally, the environmental issues are emerging in the process of mining raw material and disposal of waste batteries. Therefore, a cheap, safe, and environmentally friendly battery system is needed as an alternative to LIBs.In this situation, a battery system called seawater battery (SWB) using seawater as a raw material is attracting attention. Since seawater is super-abundant resource, accounting 97% of the earth’s water, the material and manufacturing cost can be effectively reduced. Also, since it is operated in seawater, it is free from fire hazard and environmentally benign. In addition, as natural seawater can be used without additional treatment, energy can be reduced used for refining raw materials in LIBs.Likely to other battery systems, SWB consists of anode, cathode and separator. In anode part, Na-ions originated from NaCl in seawater are plated and stripped during cycling process. For facile metal plating, the anode part is filled with organic electrolyte, which also broaden the operation voltage window of overall cell. The ceramic solid electrolyte is used as separator, which is called Na-ion selective membrane, NASICON. The cathode part contains seawater which can act as an electrolyte or cathode as well (catholyte).The reaction mechanism mechanisms of cathode part can be sorted into three types―Na-intercalation, oxygen evolution/reduction reaction, and Cl-capturing. Herein, we have focused on the intercalation cathode to realize long-life and stable SWB, which is critical properties for large-scale energy storage systems. For intercalation cathode material, Prussian blue analog (PBA) was selected. PBA is an analog form of Prussian blue (PB). Since PB/PBAs have frame-like structures consist of metal nodes and cyanide ligands, the big alkali ions including Na-ions can be inserted and released through interstitial sites. By substituting the iron of PB to other transition metals, various form of PBAs can be synthesized. Among them, Ni-based PBA (Na2Ni[Fe(CN)6] when fully sodiated) was selected, because it is known as stable in seawater and undergoing small volume change during repeating ion (de)insertion, which is advantageous properties for stable SWB application.However, during synthetic process of PBAs, when metal ions and ligands meet rapidly, vacancies are easily created inside the structure. In these empty sites, the water molecules tend to coordinate, becoming crystal water. Since crystal water negatively affects the electrochemical performance of PB/PBAs, it should be controlled. Therefore, we have controlled the structure of Ni-based PBAs by chelation and improved the electrochemical performance of SWBs.By aid of chelating agent, well-structured Ni-based PBA was successfully synthesized. The defect ratio was effectively reduced from 40% to 6%, followed by less crystal water and more Na-ions inside the structure. When applied to SWB system, the cycle performance of chelated PBA was superior to untreated PBA, exhibiting capacity retention of 92.8% after 2000 cycles at 5 C. In conclusion, showing stable and reversible operation during 2000 cycles at the first time in SWB field, PBA-based SWB showed potential to be a promising next-generation battery. Figure 1

Surfactant-Assisted Synthesis of FeF3 • 0.33 H2o and Its Application As Cathodic Material for Electrochemical Energy Storage Devices: From Lithium to Fluoride-Ion Batteries

New generation of electrochemical energy storage devices is needed to face the continuous increase in energy stored capacity demand at lower costs from human society. Moreover, due to the constant increase in number of batteries produced, the development of more sustainable devices without the consumption of limited resources at affordable costs is an actual research challenge. The conventional lithium batteries, the most widespread kind of electrochemical energy storage devices, made by an intercalation cathode (e.g., LiCoO2, LiFePO4) and a graphite anode suffer of limited capacity for high-performance application (such as in electric vehicles) and use limited mineral resources with adverse environmental consequences.Iron fluoride is a promising conversion cathode for positive electrodes in next-gen lithium batteries due to its low cost, great abundance, and ease of extraction1,2. The main problems of metal fluoride-based cathodes are the low conductivity and the structural changes during charge/discharge cycles that limit device capacity and lifespan. To effectively increase the storage capacity, several attempts to use metal lithium anodes have been made. However, this solution is now limited to primary batteries because of dendrites growth during metal plating that causes capacity fading and safety concerns.In the last decade, batteries based on fluoride-ion shuttling are drawing attention3,4 due to the possibility to use a high-capacity conversion cathode, exploiting a multi-electron transfer, and a metal anode without dendrites formation. This kind of devices, in the early stage of development, rely on electrochemical fluorination of an electropositive metal anode and the defluorination of a more “noble” metal fluoride without a metal plating-stripping process. Nowadays, electrolyte limitation is the main challenge for the development of a fluoride-ion battery that can compete with state-of-the-art lithium-ion batteries.In this work, a surfactant-assisted solvothermal route to obtain iron fluoride hydrate (FeF3 0.33 H2O) is presented. A hierarchical grape-like structure was obtained and it was tested as cathode active material in a 2025 coin-cell working in a metal-lithium battery configuration. In these tests it showed improved performance, compared to the same synthesis without surfactant. The synthetized material was also characterized by morphological and electrochemical point of view by means of Electrochemical Impedance Spectroscopy (EIS), galvanostatic charge discharge (GCD) and cyclic voltammetry (CV).The possibility to use the same cathodic material in a room-temperature fluoride-ion battery with a metal anode was assessed by using fluoride conducting liquid electrolytes5: encouraging results about the feasibility were achieved; however, further research in the field of liquid electrolytes resulted fundamental for bringing performances of this technology to the level of actual lithium batteries.

Intercalation Reaction Mechanism of Fluoride-Ions in (Ca, Sr)FeO2 Cathodes with Infinite Layer Structure for All-Solid-State Fluoride-Ion Batteries

Fluoride ion batteries, which use fluoride ions as carriers, are attracting attention as the next generation of storage batteries because of their theoretical high energy density. Conventional research has focused on metal/metal fluorides such as Cu/CuF2 as cathode materials.[1] However, these cathodes have disadvantages of the power density and cyclability due to the rapid decrease in electronic conductivity and large volume change during fluorination and defluorination. To solve these problems, cathode materials that utilize topotactic fluoride ion intercalation reactions, similar to electrode materials applied in lithium-ion secondary batteries, are being developed[2]. However, these materials have the disadvantage of relatively small capacity, compared to metal/metal fluorides.In this study, we focused on SrFeO2and Ca-doped SrFeO2 cathodes with infinite layer structure as new high-capacity intercalation cathodes, and evaluated its electrochemical properties and clarified the charge compensation mechanism.Ca1-xSrxFeO2 (x = 0, 0.2, 0.4, 0.6, 0.8, 1.0) was synthesized by a low-temperature reduction method using CaH2. Ca1-xSrxFeO2/La0.9Ba0.1F2.9/vapor grown carbon fiber (VGCF) was used as the composite cathode, La0.9Ba0.1F2.9 as the electrolyte and Pb/PbF2/ La0.9Ba0.1F2.9/VGCF as the composite anode to construct the electrochemical cell of the piezoelectric material. Charge-discharge measurements were carried out in the cut-off voltage range of -1.5 to 3.0 V at 140°C. X-ray absorption spectroscopy (XAS) measurements of Fe K-edge, O K-edge, and F K-edge and resonant inelastic X-ray scattering (RIXS) measurements of O K-edge were performed on the samples after charging and discharging.All the Ca1-xSrxFeO2 (x = 0, 0.2, 0.4, 0.6, 0.8, 1.0) cathode showed voltage plateaus around -0.5 V and 1.5 V during charging, and the maximum discharge capacity (580 mAh g-1) was obtained when x = 0.8, and the cathodes could be repeatedly charged and discharged. XAS of the Fe K-edge revealed that Fe compensated for the charge in the flat potential region around -0.5 V. XAS and RIXS measurements of the O K-edge revealed that the charge compensation was carried out by the formation of O2 molecules (oxidation of oxide ions), as which is observed in lithium-excess metal oxide on charge process[4], in the voltage plateau around 1.5 V. Using inexpensive Ca and Fe, we succeeded in developing an intercalation cathode material that significantly exceeds the capacity of conventional lithium-ion battery cathodes.

Lithium Electrode Protection for Long Cycle Life and High Rate Capability Batteries

Sion Power will present breakthrough technology leading to the highest combination of specific energy, cycle life and rate capability. In the core of this transformational energy storage solution is a protected metallic lithium anode with several levels of protection: physical barrier, chemical passivation of lithium surface, lithium morphology control through pressure application and optimal charge-discharge algorithms. Protected lithium anode combined with various intercalation cathodes offers wide spectra of cell designs with specific energies of 620 Wh/kg at 270 cycles to 400 Wh/kg and cycle life exceeding 2500 cycles.The presentation will discuss Sion Power’s technology approaches, current state of energy density, rate capability and will be more focused on impact of charge-discharge algorithms on lithium morphology and cycle life.

A Comprehensive Study of the Parameters Affecting Magnesium Plating/Stripping Kinetics in Rechargeable Mg Batteries

Beyond the lithium ion battery (LIB) technology, alkali and alkaline earth metal (Li, Na, Mg, Ca etc.) anodes boost the prospect of next generation battery chemistry through their highly promising theoretical specific capacities.1,2 Mg metal anode based battery is thus one of the strong contenders for sustainable and alternative rechargeable battery systems, with its natural abundance and eco-friendly resources.3 Despite the first proof-of-concept of a Mg battery established back in 2000,4 its complete rechargeability still remains elusive due to the lack of suitable conventional electrolytes and low mobility of Mg2+ ions in typical intercalation cathodes. Although potentially safer than Li metal (less prone to dendritic growth), reversible Mg electrodeposition in non-aqueous liquid electrolytes is a challenge due to poor salt solubility and formation of ionically blocking surface passivation films.5,6 The study of the interphase between a Mg metal anode and electrolyte is therefore of critical worth as it can dictate stability and reversibility for a particular electrode/electrolyte combination.7 In this work, we explore the role of various parameters, including electrolyte composition, concentration, solvent and substrate nature (various metals and carbon based substrates) and their impact on Mg plating/stripping kinetics and coulombic efficiency. The deposit morphology was investigated via ex situ scanning electron microscopy (SEM) and the reductive stability of the electrolytes was studied by cyclic voltammetry (CV), X-ray Photoelectron Spectroscopy (XPS) and electrochemical quartz crystal microbalance (EQCM). Overall, a comprehensive discussion about the relationship between cation solvation structure, composition and stability of passivation layer (if any) and the degree of reversibility of Mg electrodeposition will be presented. Keywords: Beyond LIB chemistry, metal anode, magnesium, EQCM, plating/stripping.