Electrochemical Potential Window Research Articles

Innovative Methylcellulose-Polyvinyl Pyrrolidone-Based Solid Polymer Electrolytes Impregnated with Potassium Salt: Ion Conduction and Thermal Properties.

In this research, innovative green and sustainable solid polymer electrolytes (SPEs) based on plasticized methylcellulose/polyvinyl pyrrolidone/potassium carbonate (MC/PVP/K2CO3) were examined. The MC/PVP/K2CO3 SPE system with five distinct ethylene carbonate (EC) concentrations as a plasticizer was successfully designed. Frequency-dependent conductivity plots were used to investigate the conduction mechanism of the SPEs. Electrochemical potential window stability and the cation transfer number of the SPEs were studied via linear sweep voltammetry (LSV) and transference number measurement (TNM), respectively. Additionally, the structural behavior of the SPEs was analyzed using Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM), X-ray diffractometry (XRD), and differential scanning calorimetry (DSC) techniques. The SPE film complexed with 15 wt.% EC measured a maximum conductivity of 3.88 × 10−4 Scm−1. According to the results of the transference number examination, cations that record a transference number of 0.949 are the primary charge carriers. An EDLC was fabricated based on the highest conducting sample that recorded a specific capacitance of 54.936 Fg−1 at 5 mVs−1.

Experimental studies on thermophysical properties of protic ionic liquids for thermal energy storage systems

Energy storage chemicals play an important role in the design of thermal energy storage systems due to their thermal and chemical properties. In this regard, ionic liquids can be used as a potential for thermal energy storage owing to their remarkable thermophysical properties. At present, little research has been done in this field. In this project, protic ionic liquids 2-hydroxyethylammonium lactate [HEA]La, bis(2-hydroxyethylammonium) lactate [BHEA]La and tris(2-hydroxyethylammonium) lactate [THEA]La were synthesized. The synthesized ionic liquids have low toxicity, high thermal stability, easy and economical synthesis with suitable physical and chemical properties for thermal energy storage systems. In the following, thermophysical measurements such as thermal conductivity, heat capacity, surface tension, density, speed of sound, and electrochemical potential windows for the pure ionic liquids at different temperatures were performed to evaluate the efficiency of these systems as thermal energy storage. The differential scanning calorimetry analysis shows that the ionic liquid 2-hydroxyethylammonium lactate has a higher heat capacity at 1.800 J·g−1·K−1 at T = 298.15 K than the other two ionic liquids due to its small cation and structure. Heat capacity also increases with increasing temperature. The electrochemical potential window values for the ILs [HEA]La, [BHEA]La and [THEA]La were obtained at 2.5 V and 2.2 V, and 1.7 V, respectively. Efficient thermal energy storage systems have a sufficiently high heat capacity and thermal energy density with beneficial thermal conductivity. The ionic liquid 2-hydroxyethylammonium lactate with a maximum thermal conductivity of 0.255 W·m−1·K−1 compared to the other two ionic liquids is recommended as an appropriate candidate for thermal energy storage.

Novel Acrylonitrile-Based Polymers for Solid–State Polymer Electrolyte and Solid-State Lithium Ion Battery

Rechargeable lithium-ion batteries (LIBs) involving lithium metal oxides, liquid electrolyte and graphite have been widely used in portable electronic devices due to their relatively high energy density and long cycle life. These desirable features make LIBs very attractive as the power source for electronic devices, hybrid electric vehicles (HEVs) and electric vehicles (EVs) applications [1, 2]. For future EV applications, higher energy density of LIBs up to 360 Wh kg-1 is required. Currently, the energy density of the state-of-the-art LIBs using conventional graphite anode, LiFePO4 (denoted as LFP) or LiNi0.5Co0.2Mn0.3O2 (NCM523) cathodes and 1-1.2 M LiPF6 in organic carbonate electrolytes provide practically achievable energy densities of up to around 200-260 Wh kg−1 [3]. When commercial graphite anodes are used, LiNi0.8Co0.15Al0.05O2 (NCA), LiNi0.8Co0.1Mn0.1O2 (NCM811), LiNi0.5Mn1.5O4 (LNMO) and LiNiPO4 (LNP) cathode based batteries with high-voltage provide energy densities of 354, 338, 351 and 414 Wh kg-1, respectively. However, LIBs using these high-voltage cathode materials and the organic carbonate electrolytes exhibit quite low thermal stability and tend to catch fire or even explode when abnormal charge/discharge cycling or accidental penetration of cells occurs, which greatly limits the automotive applications. When replacing graphite with a Li metal anode, the energy densities of all battery systems can be enhanced significantly due to the highest theoretical specific energy density (3860 mAh g-1) among all anode materials for rechargeable LIBs. Nevertheless, commercial LIBs are prone to cause safety problems due to the safety concern arising from Li dendrite growth in liquid organic electrolytes [4-6].The promising solid-state LIBs offer high thermal stability (i.e., low risk in catching fire), high energy density, wide electrochemical stability window and less environmental impact. A competent electrolyte is the key component of solid-state LIBs. The solid-state electrolyte materials are mainly classified as solid polymer electrolytes (SPEs), inorganic solid electrolytes (ISEs), and organic/inorganic composite electrolytes. ISEs include oxide-based and sulfide-based materials [7, 8], which show very high ionic conductivity (10-2 – 10-3 S cm-1). Furthermore, the lithium ion transference number is close to 1. However, the major limitation factors of practical solid-state LIB applications are the large interfacial impedance between electrode and ISE and the difficulty of processing [9]. Considering processability, mechanical flexibility, interfacial compatibility and electrochemical stability, one prefers SPEs to the inorganic ceramic electrolytes. Nevertheless, SPEs have low ion conductivities (10−7 − 10−5 S cm−1 near room temperature) and most of the Li+ transference numbers are lower than 0.5 [10, 11]. The major requirements for SPEs include high ionic conductivity and transference number at room temperature, wide electrochemical potential window, high mechanical strength and excellent thermal stability. However, the ion conductivity is the most important (> 10-4 S cm-1 at room temperature desired) and should be considered first. The coordinating groups of a good polymeric host are expected to interact with Li+ and facilitate dissociation.In this study, we prepared various novel acrylonitrile-based polymers (e.g., acrylonitrile/acrylate copolymer and polymer with two pendant groups b-cyano ethyl ether (-O-CH2CH2-CN) sulfonate alkyl ether (-O-(CH2)3SO3Li). The corresponding SPEs comprising acrylonitrile-based polymer and ca. 50 wt.% lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) with high ionic conductivity (up to 10-3 S cm-1) at room temperature, high ion transfer number (up to 0.45) and large electrochemical potential window (oxidation stability > 5 V vs. Li+/Li) achieved. The selected SPEs were used as the separator in solid-state batteries with LiFePO4 as the cathode and Li foil as the anode; and long-term cycle stability of solid-state LIB was achieved. The polymers and corresponding SPEs were characterized by using DSC, SEM, XRD and FTIR measurements. Ionic conductivities of SPEs were determined from electrochemical impedance spectroscopy results. The linear sweep voltammetry technique was adopted to measure the oxidation stability window of SPE, and the Evans-Vincent-Bruce method was used to determined ion transfer number.

Characterization of Na2M2TeO6 (M = Ni, Zn) for Oxide-Based All-Solid-State Sodium-Ion Batteries

All-solid-state sodium (Na) ion batteries (SiBs) are promising high-safety and low cost alternatives to current lithium (Li) ion batteries (LiBs), particularly suitable for the application to large-scale electrical energy storage systems. Development of inorganic solid Na-ion conducting materials used for solid electrolyte is most critical issue to realize all-solid-state SiBs. The solid electrolyte materials should have not only high Na-ion conductivity at room temperature but also chemical and electrochemical stabilities against both cathode and anode active materials. Oxide based solid electrolytes have lower conductivity and poorer deformability than sulfide based one, but they have other advantages such as their chemical stability in air and easiness for handling.Na2M2TeO6 (M = Zn, Mg, Ni, Co, etc.) with a P2-type honeycomb layered structure has been reported as a fast Na-ion conducting oxide [1]. Particularly, Na2Zn2TeO6 (NZTO) is an attractive candidate for a solid electrolyte material because of the high ionic conductivity well above 10-4 S cm-1 at room temperature, wide electrochemical potential window and lower densification temperature than other oxide-based Na-ion conductors such as NASICON and Na-β alumina [2–4]. On the other hand, Na2Ni2TeO6 (NNTO) has been investigated as a cathode active material for SiB operating at 3–4 V vs Na/Na+ [5,6]. Because of the similarity in their crystal structure and constituent elements, NNTO cathode and NZTO as solid electrolyte may be co-sintered without forming undesired secondary phases to fabricate all-solid-state SiBs.In this work, we investigated firstly the reactivity between NNTO and NZTO powders at annealing temperature between 500 ºC and 800 ºC in air. From XRD measurements, it was found that the reaction between NNTO and NZTO is negligible at annealing temperature below 700 ºC while when annealed at 800 ºC, they forms a solid-solution phase without forming any secondary phases. Based on this result, we fabricated NNTO-NZTO laminate via co-sintering NNTO and NZTO pellets at 700 ºC in air. Thicknesses of NNTO and NZTO layers in the laminate were set to 1 mm.From impedance measurements, apparent ionic conductivity of the NNTO-NZTO laminate was estimated to be approximately 0.1 mS cm-1 at 27 ºC, which is close to the prediction with taking into account only the conductivity of individually sintered NNTO (= 0.04 mS cm-1) and NZTO (= 0.36 mS cm-1) at 700 ºC. This indicates that the interfacial resistance between NNTO and NZTO layers is not so large. In addition, using the NNTO-NZTO laminate with NNTO layer thickness of 80 µm, electrochemical Na extraction reaction from NNTO layer through NZTO solid electrolyte was demonstrated via galvanostatic testing at room temperature. Obtained results are very fundamental but can be applied to fabricate all-solid-state SiBs with NNTO cathode and NZTO solid electrolyte via simple co-sintering process in future.

Fabrication of Nanocluster-Aggregated Dense Ce2(MoO4)3 Microspherical Architectures for High-Voltage Energy Storage and High Catalytic Energy Conversion Applications

Recent progress has been made toward high-performance electrochemical energy storage and energy conversion devices to overcome the energy crisis. This article highlights the performance enhancement parameter of energy storage devices such as a symmetric supercapacitor and energy conversion such as methanol oxidation and water splitting studies for the generation of efficient oxygen and hydrogen. We have prepared a dense cerium molybdate microspherical architecture by the hydrothermal route, and further physical characterization has been performed to evaluate the structural parameters. Charge storage contributions, external surface charge, and internal surface-accumulated charge are calculated by Dunn’s and Trassati’s approaches. A solid-state symmetric supercapacitor device has been assembled, which exhibits outstanding electrochemical performance with a device capacity of 198 C g–1 at 1 A g–1, a large electrochemical potential window of 2.2 V, an enormous cyclic retention of 89.5% after 10,000 cycles, a maximum specific energy of 60.5 W h kg–1, and a maximum specific power of 10.6 kW kg–1. Furthermore, the prepared microspherical architectures were evaluated for oxygen/hydrogen evolution reactions and methanol oxidation. The prepared electrode exhibits excellent oxygen evolution performance, while keeping the lowest overpotential as 316 mV, and for hydrogen evolution reaction, the overpotential was obtained as 178 mV. The microspherical architecture electrode also exhibits attractive catalytic performance for methanol oxidation and exhibits a maximum current density of 157 mA cm–2, while having an onset potential of 1.314 V (versus RHE). Thus, the prepared nanocluster-aggregated microspherical architecture of Ce2(MoO4)3 can efficiently serve as the next-generation multifunction materials for energy storage and energy conversion applications.

Influence of sodium salts on the phase and gelation behaviour of T1107 to be used as proposed polymer gel electrolyte

Aqueous electrolyte presents in batteries have high ionic conductivity. They are economic, non-flammable and offer high energy density. However, restricted thermodynamic electrochemical stable potential window of water and its spilling suppresses the use of these batteries. To address these problems, development of a polymer-based electrolyte system is an upcoming area of research. Even, the uses of sodium salts in battery electrolytes are gaining importance over lithium salts due to their abundance and economic feasibility. The present study examines the self-aggregation of star block copolymer Tetronic® 1107 in aqueous medium in the presence of sodium salts viz. sodium chloride, sodium fluoride, sodium nitrate, sodium hexafluoro phosphate and disodium hydrogen phosphate with different anions by cloud point (CP), gelation, dynamic light scattering (DLS) and small angle neutron scattering (SANS). Conductivity and DC polarization measurements are also performed for polymeric systems in the absence and also in the presence of these salts. The gelation behaviour of the block copolymer to reduce leakage problems and proper ionic conductivity of it in the presence of sodium salts make the system a credible choice as a polymer gel electrolyte (PGE).

2-Ethylhexylsulfate Anion-based Surface-Active Ionic Liquids (SAILs) as temperature persistent electrolytes for supercapacitors

We report on a comparative study of three novel non-halogenated surface-active ionic liquids (SAILs), which contain a surface-active anion, 2-ethylhexyl sulfate ([EHS]−), and phosphonium or imidazolium cations: tetrabutylphosphonium ([P4,4,4,4]+), trihexyl(tetradecyl)phosphonium ([P6,6,6,14]+), and 1-methyl-3-hexylimidazolium ([C6C1Im]+). Thermal and electrochemical properties i.e., ionic conductivities at different temperatures and electrochemical potential windows of these SAILs were thoroughly studied. SAIL's electrochemical performance as electrolytes was also examined in a multi-walled carbon nanotubes (MWCNT)-based supercapacitor over a wide range of temperatures from 253 to 373 K. We observed that the electrode material in the supercapacitor cell with [C6C1Im][EHS] as an electrolyte has a higher specific capacitance (Celec in F g−1), a higher electric energy density (E in W h kg−1), and a higher electric power density (P in kW kg−1) as compared to the other studied SAILs, [P4,4,4,4][EHS], [P6,6,6,14][EHS] and [N8,8,8,8][EHS] (from our preceding study) in a temperature range from 253 to 373 K: At the scan rate of 2 mV s−1 a supercapacitor cell with a MWCNT-based electrode and [C6C1Im][EHS], [P4,4,4,4][EHS] and [P6,6,6,14][EHS] as electrolytes has the specific capacitance, Celec = 148, 90 and 47 F g−1 and the energy density, E = 82, 50 and 26 W h kg−1, respectively, when measured at 298 K. For the named three SAILs at the scan rate of 2 mV s−1, a two- to three-fold increase in the specific capacitance and the energy density values was measured at 373 K: Celec = 290, 198 and 114 F g−1 and E = 161, 110 and 63 Wh kg−1, respectively. The solution resistance (Rs), charge transfer resistance (Rct) and equivalent series resistance (ESR) all decreased two- to three-fold with an increase in temperature from 298 to 373 K. With the high specific capacitance and enhanced energy and power density and wider electrochemical potential window as compared to the molecular organic and aqueous electrolytes, these SAILs can be used for high-temperature electrochemical applications, such as high power and energy storage devices. In particular, up to now, [C6C1Im][EHS] and [P4,4,4,4][EHS] are the most appropriate candidates for such applications.

Computational Prediction of Graphdiyne-Supported Three-Atom Single-Cluster Catalysts

Computational Prediction of Graphdiyne-Supported Three-Atom Single-Cluster Catalysts

Fabrication of a PEO-PVDF blend based polymer composite electrolyte with extremely high ionic conductivity via the addition of LLTO nanowires

In this study, fast ionic conductor electrospun Li0.33La0.55TiO3 (LLTO) nanowires were added to the PEO-PVDF blend electrolyte. We then investigated the effect of nanowire diameter and weight percentage on ionic conductivity, mechanical properties, and electrolyte performance. The results indicated that polymer composite electrolytes containing 88 nm diameter nanowires exhibited a higher ionic conductivity than those containing 161 nm or 238 nm diameter nanowires. By adding LLTO nanowires with a diameter of 238 nm, the electrochemical potential window increased to at least 4.87 V. The stability of composite polymer electrolytes containing nanowires with a diameter of 88 nm was greater than that of composite polymer electrolytes containing nanowires with a diameter of 238 nm. By adding 8 wt% LLTO nanowires with a diameter of 88 nm to the PEO-PVDF blend electrolyte, the thermal stability and ionic conductivity increased to 450 °C and 6.02 mS.cm−1, respectively.

Oxygen Redox Versus Oxygen Evolution in Aqueous Electrolytes: Critical Influence of Transition Metals.

Aqueous lithium‐ion batteries are promising electrochemical energy storage devices owing to their sustainable nature, low cost, high level of safety, and environmental benignity. The recent development of a high‐salt‐concentration strategy for aqueous electrolytes, which significantly expands their electrochemical potential window, has created attractive opportunities to explore high‐performance electrode materials for aqueous lithium‐ion batteries. This study evaluates the compatibility of large‐capacity oxygen‐redox cathodes with hydrate‐melt electrolytes. Using conventional oxygen‐redox cathode materials (Li2RuO3, Li1.2Ni0.13Co0.13Mn0.54O2, and Li1.2Ni0.2Mn0.6O2), it is determined that avoiding the use of transition metals with high catalytic activity for the oxygen evolution reaction is the key to ensuring the stable progress of the oxygen redox reaction in concentrated aqueous electrolytes.

Accelerating Pd Electrocatalysis for CO2-to-Formate Conversion across a Wide Potential Window by Optimized Incorporation of Cu.

Electrochemical reduction of carbon dioxide (CO2) to formate is a viable way to reduce CO2 emissions and realize a carbon-neutral energy cycle. Although Pd can convert CO2 to formate with a high Faradaic efficiency at minimal overpotentials, it suffers from a limited and narrow potential window. Alloying is an important strategy for the catalyst design and tuning the electronic structures. Here, we report a series of PdCu bimetallic alloy catalysts with tunable compositions based on dendritic architectures. Optimal introduction of Cu atoms into the Pd matrix facilitates formate production and suppresses CO generation. In 0.1 M KHCO3 aqueous solution, our best candidate, Pd82Cu18 catalyst, delivered a high formate Faradaic efficiency of 96.0% at -0.3 V versus RHE. More interestingly, the high selectivity (>90%) toward formate maintained an enlarged electrochemical potential window of 600 mV. The ensemble effect with electronic coupling between Pd and Cu upon alloying and its induced moderate surface O-containing configuration were found to enhance the formate formation and suppress CO poisoning during CO2 reduction.

Mesoporous electrode from human hair and bio-based gel polymer electrolyte for high-performance supercapacitor

This work reports a facile and scalable method for assembling a supercapacitor. Cost-effective solid-state supercapacitor contrived by combining waste biomass human hair derived activated carbon (HHCK) as an electrode and albumen (egg white gel polymer) in 1 M NaCl electrolyte (1 M NaCl-EWG). Human hair as an electrode precursor and egg white as a gel polymer precursor provide a sustainable approach for biomass-based material's cost-effective and eco-friendly utilization. Human hair derived interconnected three-dimensional hierarchal porous carbon of human hair possessed a high specific surface area of 1466 m2 g−1 along with the incorporation of ~23% heteroatoms into the carbon matrix. The solid-state supercapacitor (HE-SC) exhibits high specific capacitance of 491 F g−1 at 1 A g−1 within a wide electrochemical stable potential window of 1.5 V. HE-SC provided a high energy density of 38.4 W h kg−1 at 0.374 kW kg−1 power density, quick charge-discharge ability (time constant was 4.3 s), and high cyclic stability (86% capacitance retention with 95% coulombic efficiency after 6500 cycles). This current research provides a feasible and effective strategy for preparing low-cost and high-performance supercapacitors utilizing waste biomass.

Stabilized Li metal anode with robust C-Li3N interphase for high energy density batteries

The combination of commercial high-voltage cathode and a thin lithium metal anode has emerged as a promising approach to realize rechargeable high energy density lithium batteries. However, abundant challenges, including huge volume change of Li metal and its severe side reactions with electrolyte for wide electrochemical potential window, hamper the practical application of lithium metal anode in high energy density batteries. In this work, we reported a Li/graphene composite electrode with in situ formed robust C/Li3N interphase (Li/graphene-C/Li3N electrode). Stabilized by the graphene framework, the electrode can endure large volume change during lithium stripping/plating cycles and realize stable cycling. The Li3N protection layer can not only help the composite electrode to avoid the direct physical contact between active metallic lithium and electrolyte, and suppress the side reactions between them, but also help to homogenize Li+ diffusion and plating/stripping behaviors due to its high ionic conductivity. As a result, the composite structure and electrochemical interphase stability enable superior electrochemical performance of the Li/graphene-C/Li3N electrodes. As a demonstration, the Li/graphene-C/Li3N symmetric cell displayed a low and stable overpotential for more than 1000 hours at 1 mA cm−2 and 1 mAh cm−2. LCoO2||Li/graphene-C/Li3N cell delivered a high energy density of 694.05 Wh kg−1 in the working potential range between 2.8 V and 4.6V and displayed high Coulombic efficiency of over 99% for more than 150 cycles, showing promising for practical high energy density lithium metal batteries.

Zn anode sustaining high rate and high loading in organic electrolyte for rechargeable batteries

Rechargeable aqueous Zn battery, the promising candidate for future energy storage devices still suffers from multiple disadvantages of low reversibility, uncontrolled dendrite growth, and limited electrochemical potential window. Alternatively, organic electrolytes can theoretically resolve the thermodynamic instability of Zn anode, but at the expense of high-rate capability due to their inferior ionic conductivity. Here we report N, N-dimethyl formamide (DMF) based non-aqueous electrolyte containing Cu2+ ions as an additive (Cu2+-DMF). The combined effect of high thermodynamic stability of Zn anode in DMF electrolyte and in-vitro Cu-Zn alloy interphase can surpass both aqueous and non-aqueous electrolyte performance. High-rate capability, low overpotential of ∼50 mV at 20.0 mA cm−2/20.0 mAh cm−2, supreme stability over 1400 h at 5.0 mA cm−2/5.0 mAh cm−2, high Coulombic efficiency (CE, ∼99.60 %) and wide electrochemical stability window (∼2.45 V vs. Zn/Zn2+) is observed for Cu2+-DMF electrolyte. As a proof-of-concept, Zn||δ-MnO2 battery configuration in DMF electrolyte exhibits stable cycling, high-rate capability, and excellent reversibility. For deep understanding, the electrochemical kinetics and storage mechanism are also validated through multiple characterization techniques. This work is a substantial step towards the cost-effective construction of rechargeable non-aqueous Zn ion batteries.

Green solvents for extractive separation of Pb(II) and Hg(II) from various resources-An update

Heavy metals such as lead and mercury pollution are irreversible and stay for long time.The handling of wastes come out of industries, agriculture, domestic uses is very difficult to deal with. Hydro metallurgical technique like solvent extraction offers huge scope for the extraction,separation and purification of these waste materials in order to extract these metal values. The feasibility of ionic liquid as green solvents in the recovery of heavy metal ions like Pb(II) and Hg(II) from diverse resources are analyzed in this review. Ionic liquids, or salts having low melting temperature , have a number of benefits, including being long-lasting and environmentally friendly green solvents. Because of their specific attributes, like low vapour pressure, inflammability, less toxic character, appreciable ionic conductivity as well as a broad electrochemical potential window, these have got numerous application into diverse sectors, including hydro metallurgy. Despite the fact that a number of papers have been published on ionic liquids, pertinent research outcomes in the area of hydro metallurgical methods are very less. Due to the fact that investigation and use in this area are still in its early stages,more fundamental approaches to popularize these green solvents in the metal processing industries will be more challenging.Ammonium and phosphonium based ionic liquids have more stability than imidazolium based ionic liquids.Extraction process parameters like pH, time of extraction, extractant concentration, optimum temperature, volume ratio of both aqueous and organic phases in different extraction systems and their influences the extraction efficiency have been summarized.

Organic ionic plastic crystal enhanced interface compatibility of PEO-based solid polymer electrolytes for lithium-metal batteries

Polyethylene oxide (PEO)-based solid polymer electrolytes (SPEs) are appealing solid electrolytes for lithium-metal batteries (LMBs) due to their high safety, low cost and flexibility. However, PEO'snarrow electro-chemical potential window and poor interfacial compatibility with the electrode restrict PEO-based SPE development. Herein, we used a solution-casting method to prepare PEO-based SPE membranes reinforced with an organic ionic plastic crystal—N,N-diethylpyrrolidinium bis(fluorosulfonyl)amide (C2epyrFSI). The as-prepared SPE exhibits high ionic conductivity of 3.02 × 10−4 S cm−1 at 50 °C, an extremely wide electro-chemical window (5.1 V) and flexible mechanical properties. Using SPE, the Li symmetric cells can cycle for 2000 h at a current density of 0.1 mA cm−2 without short circuiting at 50 °C. Furthermore, the Li|SPE|LiFePO4 all-solid-state LMBs have a high initial discharge specific capacity of 157.3 mAh g−1 at 0.2C and a capacity retention rate of 96% after 120 cycles. This study shows that the PEO-C2epyrFSI SPE is a promising electrolyte for all-solid-state LMBs.

Electrical, electrochemical and structural studies of a chlorine-derived ionic liquid-based polymer gel electrolyte.

In the present article, an ionic liquid-based polymer gel electrolyte was synthesized by using poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP) as a host polymer. The electrolyte films were synthesized by using the solution casting technique. The as-prepared films were free-standing and transparent with good dimensional stability. Optimized electrolyte films exhibit a maximum room-temperature ionic conductivity of σ = 8.9 × 10−3 S·cm−1. The temperature dependence of the prepared polymer gel electrolytes follows the thermally activated behavior of the Vogel–Tammann–Fulcher equation. The total ionic transference number was ≈0.91 with a wider electrochemical potential window of 4.0 V for the prepared electrolyte film which contains 30 wt % of the ionic liquid. The optimized films have good potential to be used as electrolyte materials for energy storage applications.

Polyphenylene Sulfide-Based Solid-State Separator for Limited Li Metal Battery.

The urgent need for high energy batteries is pushing the battery studies toward the Li metal and solid-state direction, and the most central question is finding proper solid-state electrolyte (SSE). So far, the recently studied electrolytes have obvious advantages and fatal weaknesses, resulting in indecisive plans for industrial production. In this work, a thin and dense lithiated polyphenylene sulfide-based solid state separator (PPS-SSS) prepared by a solvent-free process in pilot stage is proposed. Moreover, the PPS surface is functionalized to immobilize the anions, increasing the Li+ transference number to 0.8-0.9, and widening the electrochemical potential window (EPW > 5.1V). At 25°C, the PPS-SSS exhibits high intrinsic Li+ diffusion coefficient and ionic conductivity (>10-4 S cm-1 ), and Li+ transport rectifying effect, resulting in homogenous Li-plating on Cu at 2mA cm-2 density. Based on the limited Li-plated Cu anode or anode-free Cu, high loadings cathode and high voltage, the Li-metal batteries (LMBs) with polyethylene (PE) protected PPS-SSSs deliver high energy and power densities (>1000Wh L-1 and 900 W L-1 ) with >200cycling life and high safety, exceeding those of state-of-the-art Li-ion batteries. The results promote the Li metal battery toward practicality.

Voltammetric investigation of anodic and cathodic processes at Au(hkl)|ionic liquid interfaces

• The electrochemical behaviors of 8 ionic liquids (ILs) were studied on Au( hkl ). • Pyrrolidinium-based ILs had the widest electrical double-layer region. • The potential windows depended on Au( hkl ) and the ions comprising the ILs. • The desorption/re-adsorption of iodine for 2 iodide-based ILs depended on Au( hkl ). • In terms of the peak potential for iodine desorption: Au(100) < Au(111) < Au(110) . In this work, the effect of the crystallographic orientation of gold on the interfacial processes of six non-halide-based ionic liquids (ILs) and two iodide-based ILs was systematically investigated by linear sweep voltammetry (LSV), cyclic voltammetry (CV), and double potential step chronocoulometry (DPSCC). The cation and anion of the IL affected both the width of the electrical double-layer (EDL) region ( E dl ) and the electrochemical potential window ( E pw ) of the ILs. The shape of the CV profile in the EDL region was unique for each Au( hkl )|IL interface. The reductive desorption and re-adsorption of iodine adatoms on gold in 1-alkyl-3-methylimidazolium iodide ([C n mim][I], n = 4 or 6) were also surface-sensitive. The reduction peak current density was proportional to the scan rate, suggesting that the reaction involves adsorbed iodine. The amount of iodine adatoms desorbed during the initial cathodic scan was identical to the monolayer coverage of iodine on gold single crystal electrodes. The peak potential for reductive desorption was estimated to follow the ensuing order from negative to positive: [C 6 mim][I] < [C 4 mim][I] and Au(100) < Au(111) < Au(110) . Following reductive desorption of iodine, the cations were partly attached to the gold surface. The adsorption strength of [C n mim] + followed an identical order: Au(100) < Au(111) < Au(110) .

Highly Reversible Zn Metal Anode Stabilized by Dense and Anion‐Derived Passivation Layer Obtained from Concentrated Hybrid Aqueous Electrolyte

AbstractZinc metal is considered a promising anode material for aqueous zinc ion batteries. However, it suffers from dendrite growth, corrosion, and low coulombic efficiency (CE) during plating/stripping. Herein, a concentrated hybrid (4 m Zn(CF3SO3)2 + 2 m LiClO4) aqueous electrolyte (CHAE) to overcome the challenges facing the Zn anode is reported. The developed electrolyte achieves dendrite‐free Zn plating/stripping and obtains an excellent CE of ≈100%, surpassing the previously reported values. The combination of synchrotron‐based in operando transmission X‐ray microscopy, X‐ray diffraction, and ex situ X‐ray photoelectron spectroscopy analyses indicate that the denser, anion‐derived passivation layer formed using the CHAE facilitates homogeneous current distribution and better prevents freshly deposited Zn from directly contacting the electrolyte than the looser, solvent‐derived layers formed from a dilute hybrid aqueous electrolyte (DHAE). The beneficial effects of the CHAE on the compact, dense, and stable salt‐anion‐derived passivation layer can be attributed to its unique solvation structure, which suppresses the water‐related side reactions and widens the electrochemical potential window. In the hybrid Zn||LiFePO4 configuration, the CHAE‐based cell delivered a stable performance of CE &gt;99% and capacity retention &gt;90% after 285 cycles. In contrast, the DHAE‐based cell exhibits capacity retention of &lt;65% after 170 cycles.