Behavior Of Electrolytes Research Articles

Fundamental study on Zn corrosion and dendrite growth in gel electrolyte towards advanced wearable Zn-ion battery

Wearable Zinc-ion batteries (ZIBs) are considered a promising energy storage device due to their superiorities in both safety and cost.However, the Zn reversibility in wearable ZIBs has not been yet studied.Here, our study reveals that gel electrolytes can suppress the dendrite growth to prolong the Zn lifespan, but they cannot addresscorrosion reactions, resulting in poor reversibility.To further enhance the mechanical properties of gel electrolyte and Zn reversibility,a functional double-network hydrogel electrolyte (FDHE) is designed, in which the unique poly-2-Acrylamido-2-methylpropanesulfonic/polyacrylamide (PAMPS/PAAM)structure provides a robust mechanical property.Meanwhile,the additive of dimethyl sulfoxide as an H-acceptor and solvation regulator is added during the synthesisofFDHE,which not only inhibits side reactions by reducing the activity of free water but also diminishes the de-solvation energy barrier by regulating the Zn2+ solvation structure.Consequently, the Zn electrode in FDHE-based Zn coin-cell displays excellent reversibility even under −10 °C.After assembling wearable ZIBs, outstanding performance is also achieved under different bending states.Our study provides an in-depth understanding of Zn behavior in gel electrolytes and paves the way to design next-generation wearable ZIBs.

Rheological behavior of gel polymer electrolytes: yield stress and viscoelasticity

In redox flow batteries (RFBs), semi-solid flow cells incorporate solid particles in the same medium than the electrolyte in the form of slurry to increase energy efficiency. However, rheological properties of the fluid hosting the solid particles need to favor particle stability and pumping process within the RFB. In this study, the materials used to formulate a gelled polymer electrolyte (GPE), which will be used as a suspending fluid for dense zinc microparticles in a zinc slurry-air RFB, were analyzed. It was found that when using polyacrylic acid and attapulgite gelling agents together, a yield stress behavior was obtained. This satisfactory result was accomplished even in harsh alkaline conditions (pH > 14), representative of the battery operation conditions in which the chemical stability of gelling agents is threatened. Yield stress values were obtained by fitting experimental data to the Herschel-Bulkley model, and results were compared to those obtained by creep tests. Results indicate that the GPEs presented in this study are good candidates to host zinc microparticles for a zinc slurry-air RFB.Graphical abstract

Rate-dependent deformation of amorphous sulfide glass electrolytes for solid-state batteries

Sulfide glasses are emerging as potential electrolytes for solid-state batteries. The mechanical behavior of these materials can significantly impact cell performance, and it is thus imperative to understand their deformation and fracture mechanisms. Previous work mainly reports properties obtained under quasi-static loading conditions, but very little is known about deformation under dynamic conditions. The current investigation shows that the sulfide glass mechanical behavior is dominated by viscoplasticity, differing substantially from polycrystalline oxide and sulfide solid electrolytes. Finite element modeling indicates that the sulfide glass stiffness is high enough to maintain good contact with softer lithium metal electrodes under moderate stack pressures. The observed viscoplasticity also implies that battery operating conditions will play an important role in electro-chemo-mechanical processes that are associated with dendritic lithium penetration. In general, the rate-dependent mechanical behavior of the sulfide glass electrolytes documented here offers a new dimension for designing next-generation all-solid-state batteries.

From room temperature to harsh temperature applications: Fundamentals and perspectives on electrolytes in zinc metal batteries.

As one of the most competitive candidates for the next-generation energy storage systems, the emerging rechargeable zinc metal battery (ZMB) is inevitably influenced by beyond-room-temperature conditions, resulting in inferior performances. Although much attention has been paid to evaluating the performance of ZMBs under extreme temperatures in recent years, most academic electrolyte research has not provided adequate information about physical properties or practical testing protocols of their electrolytes, making it difficult to assess their true performance. The growing interest in ZMBs is calling for in-depth research on electrolyte behavior under harsh practical conditions, which has not been systematically reviewed yet. Hence, in this review, we first showcase the fundamentals behind the failure of ZMBs in terms of temperature influence and then present a comprehensive understanding of the current electrolyte strategies to improve battery performance at harsh temperatures. Last, we offer perspectives on the advance of ZMB electrolytes toward industrial application.

Optimization of LIB Electrolyte and Exploration of Novel Compounds via the Molecular Dynamics Method

Due to great interest in the development of electric vehicles and other applications, improving the performances of lithium-ion batteries (LIBs) is crucial. Specifically, components of electrolytes for LIBs should be adequately chosen from hundreds of thousands of candidate compounds. In this study, we aimed to evaluate some physical properties expected for combinations of molecules for electrolytes by microscopic simulations. That is, the viscosity, ionic conductivity, degree of dissociation, diffusion coefficient, and conformation of each molecule were analyzed via molecular dynamics (MD) simulations. We aimed to understand how molecular-sized structures and properties collaboratively affect the behavior of electrolytes. The practical models of molecules we used were ethylene carbonate (EC), fluoroethylene carbonate (FEC), propylene carbonate (PC), butylene carbonate (BC), γ-butyrolactone (GBL), γ-valerolactone (GVL), dimethyl carbonate (DMC), ethyl-methyl carbonate (EMC), diethyl carbonate (DEC), and lithium hexafluorophosphate (LiPF6). Many molecular systems of electrolytes were simulated, in which one molar LiPF6 was mixed into a single or combined solvent. It was found that small solvent molecules diffused with relative ease, and they contributed to the higher ionic conductivity of electrolytes. It was clarified that the diffusion coefficient of lithium (Li) ions is greatly affected by the surrounding solvent molecules. We can conclude that high-permittivity solvents can be selectively coordinated around Li ions, and Li salts are sufficiently dissociated, even when there is only a small content of high-permittivity solvent. Thus, we can confirm solely by MD simulation that one of the better candidates for solvent molecules, formamide (F), will exhibit higher performance than the current solvents.

Proposing an Ultrapure Water Unit Coupled to an Existing Reverse Osmosis Desalination Plant and its Exergy Analysis

In this study, three desalination exergy analysis models including the Cerci et al. model (Model A), Drioli et al. model (Model B) and electrolyte solution model (Model C), were developed on an existing reverse osmosis (RO) desalination plant in Oman (Plant ALG). A modified ultrapure water (UPW) unit fed by Plant ALG has also been proposed (Plant A) based on the technology used in a UPW unit operated under the climate of Europe and fed by European river water (Plant B). The most suitable exergy model for characterizing the proposed UPW production plant was used. Model C was found to be the most proper model among its counterparts. It reflected the electrolytic behavior of the relevant streams and considered as the appropriate model. The major exergy destruction sites were also identified, and the exergy efficiency was calculated. The electro-de-ionization (EDI) and the RO unit were the highest exergy destructive components in Plant A.

Coupling of graphene quantum dots with MnO2 nanosheets for boosting capacitive storage in ionic liquid electrolyte

Utilizing ionic liquid (IL) as electrolyte to fabricate supercapacitor is an effective strategy for increasing its operating voltage and energy density. Although manganese dioxide (MnO2) can exhibit pseudocapacitive storage behavior in some specific IL electrolytes, it still suffers from low specific capacitance as well as unsatisfactory kinetics. Herein, a new design of graphene quantum dots (GQDs) integrated with MnO2 nanosheets is proposed to construct a GQDs@MnO2 composite electrode for IL-based supercapacitor. Synergistically coupling of GQDs with MnO2 nanosheets provides a 3D nanoflower architecture with increased surface area, enhanced electrochemical kinetics and excellent structural integrity. The GQDs play an important role in modifying the density of state and energy bandgap as well as enhance the electronic conductivity of GQDs@MnO2 electrode. These properties endow the superior capacitive storage, rapid charge–discharge response and high electrochemical reversibility for GQDs@MnO2 electrode in IL electrolyte. For real-life application, a high-performance flexible IL-based supercapacitor is assembled, which can deliver a high energy density (82.2 Wh kg−1), a high power density (11.6 kW kg−1), and long-term cycle performance upon the straight and bent states, suggesting its great potential in energy-related technologies and portable electronics.

Conductivity gradient modulator induced highly reversible Li anodes in carbonate electrolytes for high-voltage lithium-metal batteries

Lithium metal has been considered as the ultimate anode for rechargeable batteries due to its lowest redox potential and ultra-high theoretical capacity. Nevertheless, uneven Li deposition, uncontrolled dendrite growth, and fragile solid electrolyte interphase (SEI) seriously impede the widespread application of lithium-metal batteries (LMBs), especially those cycled in carbonate electrolytes. Herein, a flexible LiNO3-modified conductivity gradient host (LNOCGH), which comprises a dielectric top layer with excess decorated LiNO3 particles and carbon nanofiber layers with upward attenuation of electrical conductivity, is demonstrated to manipulate Li deposition behavior in carbonate electrolytes. The top layer can steadily release LiNO3 to form a robust nitride-rich SEI while the conductivity gradient structure endows Li deposited in a dendrite-free manner by shifting the preferential deposition spots from the anode/separator interface to the anode bottom, which is confirmed through experiments and simulations. Benefiting from the elaborate and comhensive design, the stability of LNOCGH electrodes was significantly improved. The full cell with limited LNOCGH@Li anodes and high mass-loading LiNi0.8Co0.1Mn0.1O2 cathodes (N/P ratio of 2.3) can work stably for over 60 cycles with 72.9% capacity retention. As a proof-of-concept, flexible quasi-solid electrolyte can also be assembled with the as-obtained anode enables flexible LMB with excellent electrochemcial performance.

A tailor-made deep eutectic solvent for 2.2 V wide temperature-tolerant supercapacitors via optimization of N,N-dimethylformamide/water co-solvents

A high-performing electrolyte plays an imperative role in the pursuit of high energy density, green, low-cost, and safe supercapacitors. To this end, a novel deep eutectic solvent (DES) composed of N-methylacetamide and lithium perchlorate has been engineered by the addition of co-solvents including water and N,N -dimethylformamide (DMF). Interestingly, each co-solvent makes a specific contribution to DES performance as water for flame resistance and DMF for antifreeze. The optimized hybrid DES is tested as the electrolyte for symmetric supercapacitors with polyaniline/reduced graphene oxide composite electrodes (PANI-rGO). The hybrid DES with high ionic conductivity imparts a high operation voltage of 2.2 V to devices whereas the PANI-rGO electrode with the pseudocapacitive behavior provides the high capacitances. Due to the above synergistic effects, our device delivers the maximum energy density of 28.2 W h kg −1 at a power density of 1.1 kW kg −1 and shows moderate cyclic stability at room temperature. More importantly, the supercapacitors can well function in a low temperature range from −20 to 25 °C. The device operated at 25 °C achieves the maximum capacitance of 41.9 F g −1 due to improved ionic conductivity of the DES electrolyte. The current study opens a new route towards sustainable and affordable energy storage devices. • DES electrolyte with N,N -dimethylformamide as co-solvent shows 2.2V window. • PANI-rGO exhibits pseudocapacitive behavior in the hybrid DES electrolyte. • Fabricated symmetric supercapacitor has potential to operate from −20 to 70 °C. • It delivers an energy density of 28.2 W h kg −1 at a power density of 1.1 kW kg −1

Photodegradation and electrolytic behaviour investigations of cationic amphiphiles based self-assembled non-aqueous layered lamellar interfaces

Photodegradation and electrolytic behaviour investigations of cationic amphiphiles based self-assembled non-aqueous layered lamellar interfaces

Chronopotentiometric Evaluation of Ionization Degree and Dissociation Constant of Imidazolium-Based Ionic Liquid [C6Meim][NTf2] in Polymeric Plasticized Membranes.

Ionic liquids (ILs) have a wide variety of applications in modern electrochemistry due to their unique electrolytic properties. In particular, they are promising candidates as dopants for polymeric membranes in potentiometric sensors and liquid-junction free reference electrodes. However, the effective use of ILs requires a comprehensive understanding of their electrolytic behavior in the polymeric phase. We report here the exploration of the electrolytic and diffusion properties of IL 1-hexyl-3-methyl-1H-imidazol-3-ium bis[(trifluoromethyl)sulfonyl]amide ([C6Meim][NTf2]) in a poly(vinyl chloride) matrix. Chronopotentiometry is utilized to determine the concentration of charge carriers, ionic diffusion coefficients and apparent dissociation constant of [C6Meim][NTf2] in PVC membranes plasticized with a mixture of [C6Meim][NTf2] and bis(2-ethylhexyl) sebacate (DOS) over a wide range of IL concentrations. The diffusion properties of [C6Meim][NTf2] are confirmed by NMR-diffusometry. The non-monotonic electrolytic behavior of the IL in PVC-DOS matrix is described for the first time. A maximum ionization degree and diffusion coefficient is observed at 30 wt.% of IL in the plasticizing mixture. Thus, it is shown that by varying the flexible parameter of the IL to plasticizer ratio in the polymeric phase one can tune the electrolytic and transport properties of sensing PVC membranes.

Molecular dynamics investigation of charging process in polyelectrolyte-based supercapacitors

Supercapacitors are one of the technologically impressive types of energy storage devices that are supposed to fill the gap between chemical batteries and dielectric capacitors in terms of power and energy density. Many kinds of materials have been investigated to be used as supercapacitors’ electrolytes to overcome the known limitations of them. The properties of polymer-based electrolytes show a promising way to defeat some of these limitations. In this paper, a simplified model of polymer-based electrolytes between two electrodes is numerically investigated using the Molecular Dynamics simulation. The simulations are conducted for three different Bjerrum lengths and a typical range of applied voltages. The results showed a higher differential capacitance compared to the cases using ionic-liquid electrolytes. Our investigations indicate a rich domain in molecular behaviors of polymer-based electrolytes that should be considered in future supercapacitors.

Finite element-based analysis of composite serpentine flow channel 3D modeling of vanadium redox flow battery

ABSTRACT The flow channel design significantly affects the operating performance of the vanadium redox flow battery (VRB). Serpentine flow channels enable uniform distribution of electrolyte concentration, which are widely used in flow channel design. However, this design leads to high electrolyte pressure drop and increased pump losses, thus reducing operating efficiency. To solve this problem, this paper proposes a novel composite serpentine channel design. The flow channel can significantly reduce the problem of excessively high electrolyte pressure drop inside the cell. In this paper, based on conservation laws of momentum, mass, charge and reaction kinetics, a three-dimensional model of a composite serpentine flow channel vanadium redox flow battery is developed to analyze the electrolyte behavior the COMSOL Multiphysics platform. The simulation results show that the pressure drop of the composite serpentine flow channel is largely reduced compared with that of the serpentine flow channel. The novel design can effectively reduce the pressure drop, and thus reduce the pump loss, which provides a guidance for VRB flow channel design.

Suppressing electrolyte-lithium metal reactivity via Li+-desolvation in uniform nano-porous separator

Lithium reactivity with electrolytes leads to their continuous consumption and dendrite growth, which constitute major obstacles to harnessing the tremendous energy of lithium-metal anode in a reversible manner. Considerable attention has been focused on inhibiting dendrite via interface and electrolyte engineering, while admitting electrolyte-lithium metal reactivity as a thermodynamic inevitability. Here, we report the effective suppression of such reactivity through a nano-porous separator. Calculation assisted by diversified characterizations reveals that the separator partially desolvates Li+ in confinement created by its uniform nanopores, and deactivates solvents for electrochemical reduction before Li0-deposition occurs. The consequence of such deactivation is realizing dendrite-free lithium-metal electrode, which even retaining its metallic lustre after long-term cycling in both Li-symmetric cell and high-voltage Li-metal battery with LiNi0.6Mn0.2Co0.2O2 as cathode. The discovery that a nano-structured separator alters both bulk and interfacial behaviors of electrolytes points us toward a new direction to harness lithium-metal as the most promising anode.

Physical and Electrochemical Behavior of Affordable Na3sbs4 Solid Electrolyte at Different Heat Treatment Temperatures

Physical and Electrochemical Behavior of Affordable Na3sbs4 Solid Electrolyte at Different Heat Treatment Temperatures

Sodium niobates and protonic niobates nanowires obtained from hydrothermal synthesis: Electrochemical behavior in aqueous electrolyte

Niobium-based oxides can be used in several applications due to a diverse set of properties. In this work, Na 2 Nb 2 O 6 .H 2 O sodium niobate nanowires were obtained by hydrothermal synthesis at low temperature. Dehydrated sodium niobate (Na 2 Nb 2 O 6 ) and sodium niobate with perovskite structure (NaNbO 3 ) were obtained by submitting Na 2 Nb 2 O 6 .H 2 O to heat treatment (350 °C and 500 °C, respectively). To obtain protonic niobates, sodium niobates were immersed in nitric acid in order to promote ion exchange reactions. From this procedure, protonic niobates (H 3 O) 2 Nb 2 O 6 .H 2 O and (H 3 O) 2 Nb 2 O 6 were obtained. The sample NaNbO 3 did not undergo any transformation. Cyclic voltammetry tests carried out in a neutral aqueous solution 1 M Na 2 SO 4 showed a wide potential window for both niobates (sodium and protonic). However, the protonic niobate samples (H 3 O) 2 Nb 2 O 6 .H 2 O and (H 3 O) 2 Nb 2 O 6 presented much higher current density values than the sodium niobates. This result can be related to a structural rearrangement that allowed a significant increase in the intercalation of sodium Na + ions from the electrolyte into the structure of these protonic niobates, when polarized. Therefore, in this work, it was demonstrated that it is possible to obtain protonic niobates from sodium niobates, as well as, it was verified the distinct electrochemical behavior between these materials.

Concentration-dependent ion correlations impact the electrochemical behavior of calcium battery electrolytes.

Ion interactions strongly determine the solvation environments of multivalent electrolytes even at concentrations below that required for practical battery-based energy storage. This statement is particularly true of electrolytes utilizing ethereal solvents due to their low dielectric constants. These solvents are among the most commonly used for multivalent batteries based on reactive metals (Mg, Ca) due to their reductive stability. Recent developments in multivalent electrolyte design have produced a variety of new salts for Mg2+ and Ca2+ that test the limits of weak coordination strength and oxidative stability. Such electrolytes have great potential for enabling full-cell cycling of batteries based on these working ions. However, the ion interactions in these electrolytes exhibit significant and non-intuitive concentration relationships. In this work, we investigate a promising exemplar, calcium tetrakis(hexafluoroisopropoxy)borate (Ca(BHFIP)2), in the ethereal solvents 1,2-dimethoxyethane (DME) and tetrahydrofuran (THF) across a concentration range of several orders of magnitude. Surprisingly, we find that effective salt dissociation is lower at relatively dilute concentrations (e.g. 0.01 M) than at higher concentrations (e.g. 0.2 M). Combined experimental and computational dielectric and X-ray spectroscopic analyses of the changes occurring in the Ca2+ solvation environment across these concentration regimes reveals a progressive transition from well-defined solvent-separated ion pairs to de-correlated free ions. This transition in ion correlation results in improvements in both conductivity and calcium cycling stability with increased salt concentration. Comparison with previous findings involving more strongly associating salts highlights the generality of this phenomenon, leading to important insight into controlling ion interactions in ether-based multivalent battery electrolytes.

Synthesis of Garnet Llzo by Aliovalent Co-Doping, and Electrochemical Behavior of Composite Solid Electrolyte for All-Solid Lithium Batteries

Synthesis of Garnet Llzo by Aliovalent Co-Doping, and Electrochemical Behavior of Composite Solid Electrolyte for All-Solid Lithium Batteries

Influence of the Number of Dimensions in the Impedance Spectroscopy Simulation of a YSZ Electrolyte

The use of computer simulation to predict the behavior of devices and materials allows for the acceleration of system operation and reduces costs, as it eliminates the need to build prototypes for testing. This work proposes the construction of 3 models with different complexities to simulate the electrical behavior of a solid electrolyte fuel cell. Experimental data were compared with simulation data. The experimental data were obtained from the production of a solid YSZ by tape casting, sintered at 1550 °C. The material was characterized using impedance spectroscopy in atmospheric air. From the experimental data, a computer simulation was conducted by using commercial code (COMSOL Multiphysics v.5.4). The construction of the model was developed to 1D, 2D axisymmetric and 3D dimensions to simulate an electrolyte to use in cylindrical planar SOFC. Nyquist Impedance graphics were plotted for the three geometries in comparison with the experimental value. No variation was observed between the curves obtained by the different geometries for the same interface. In other words, the interface complexity did not interfere in the result obtained for the same experimental data. We concluded that the 1D model is ideal to predict the influence of operational parameters because it is simpler and saves analysis time, maintaining the reliability and accuracy of the results.

Prospects and insights of protic ionic liquids: The new generation solvents used in fuel cells

The environmental pollution caused by rapid industrialization has augmented for several decades and there is a communal anticipation to design maintainable chemical processes so that fewer toxic materials are generated. Recently ionic liquids and its derived systems are projected as alternatives for traditional solvents because of their clean, effective and environment friendly nature. This class of solvents are tagged as ‘’designer solvents’’ due to their tunable nature and incomparable properties. The potential of ionic liquids has expanded in terms publications, so this review is devoted to a subclass of ionic liquids i.e., protic ionic liquids (PILs) with a special stress on their physicochemical properties like high thermal, electrochemical and ionic conductivity. Protic ionic liquids serve as perfect electrolytes and exhibit proton conductivity as well as activity in fuel cell electrode reactions. The good electrolytic behavior facilitates proton transport in non-aqueous condition which is one of the vital requirements in proton exchange membrane fuel cell. To exhibit better thermal stability the PIL based fuel cell electrolyte should have ΔpKa greater than 15 since the open circuit voltage displays maximum ΔpKa in the range of 16–18. PILs offer to be promising candidate for fuel cell applications and greatly enables the use of renewable energy sources.