Next-generation aqueous flow battery chemistries

The battery industry is seeking solutions for large-scale energy storage that are affordable, durable, and safe. Aqueous redox flow batteries (RFBs) have the inherent properties to meet these requirements. While much has been learned over the past decade on the properties of redox materials, the focus of next-generation systems must be primarily on lowering redox material cost and increasing durability. In this context, in addition to inexpensive materials such as iron salts, redox couples based on small organic molecules have shown significant promise. A considerable level of understanding has been gained on the factors affecting the durability of aqueous RFB systems, specifically relating to molecular stability and crossover. New molecular classes, substituent strategies, and cell configurations have been identified to enhance the durability of systems in the future. Next-generation systems will also need to focus on designing molecules for achieving high energy efficiency and power density as well. Furthermore, the application of computational methods for screening of chemical stability could accelerate discovery of new molecular architectures.     

A symmetric aqueous redox flow battery based on viologen derivative

Due to the diversity and feasibility of structural modification for organic molecules,organic-based redox flow batteries(ORFBs) have been widely investigated,especially in aqueous solution under neutral circumstance.In this work,a symmetric aqueous redox flow battery(SARFB) was rationally designed by employing a bipolar redox active molecule(N,N'-dimethyl-4,4-bipyridinium diiodide,MVI_2) as both cathode and anode materials and combining with an anion exchange membrane.For one MVI_2 flow battery,MV~(2+)/MV~(·+) and I~-/I_3~-serve as the redox couples of anode and cathode,respectively.The MVI_2 battery with a working voltage of 1.02 V exhibited a high voltage efficiency of 90.30% and energy efficiency of 89.44% after 450 cycles,and crossover problem was prohibited.The comparable conductivity of MVI_2 water solution enabled to construct a battery even without using supporting electrolyte.Besides,the bipolar character of MVI_2 battery with/without supporting electrolyte was investigated in the voltage range between-1.2 V and 1.2 V,showing excellent stable cycling stability during the polarity-reversal test.     

A single-ion conducting covalent organic framework for aqueous rechargeable Zn-ion batteries

Despite their potential as promising alternatives to current state-of-the-art lithium-ion batteries, aqueous rechargeable Zn-ion batteries are still far away from practical applications. Here, we present a new class of single-ion conducting electrolytes based on a zinc sulfonated covalent organic framework (TpPa-SO₃Zn_0.5) to address this challenging issue. TpPa-SO₃Zn_0.5 is synthesised to exhibit single Zn²⁺ conduction behaviour via its delocalised sulfonates that are covalently tethered to directional pores and achieve structural robustness by its β-ketoenamine linkages. Driven by these structural and physicochemical features, TpPa-SO₃Zn_0.5 improves the redox reliability of the Zn metal anode and acts as an ionomeric buffer layer for stabilising the MnO₂ cathode. Such improvements in the TpPa-SO₃Zn_0.5–electrode interfaces, along with the ion transport phenomena, enable aqueous Zn–MnO₂ batteries to exhibit long-term cyclability, demonstrating the viability of COF-mediated electrolytes for Zn-ion batteries.

A zinc sulfonated covalent organic framework is presented as a new single-ion conducting electrolyte for aqueous rechargeable Zn-ion batteries.     

Highly stable aqueous rechargeable Zn-ion battery: The synergistic effect between NaV_6O_(15) and V_2O_5 in skin-core heterostructured nanowires cathode

The aqueous rechargeable Zn-ion batteries based on the safe,low cost and environmental benignity aqueous electrolytes are one of the most compelling candidates for large scale energy storage applications.However,pursuing suitable insertion materials may be a great challenge due to the strong electrostatic interaction between Zn^{^(2+})and cathode materials.Hence,a novel NaV₆O₁₅/V₂O₅ skin-core heterostructure nanowire is reported via a one-step hydrothermal method and subsequent calcination for high-stable aqueous Zn-ion batteries(ZIBs).The NaV₆O₁₅/V₂O₅ cathode delivers high specific capacity of 390 m Ah/g at 0.3 A/g and outstanding cycling stability of 267 m Ah/g at 5 A/g with high capacity retention over 92.3%after 3000 cycles.The superior electrochemical performances are attributed to the synergistic effect of skin-core heterostructured NaV₆O₁₅/V₂O₅,in which the sheath of NaV₆O₁₅ possesses high stability and conductivity,and the V₂O₅ endows high specific capacity.Besides,the heterojunction structure not only accelerates intercalation kinetics of Zn²⁺transport but also further consolidates the stability of the layers of V₂O₅ during the cyclic process.This work provides a new perspective in developing feasible insertion materials for rechargeable aqueous ZIBs.     

Prussian blue analogues as aqueous Zn-ion batteries electrodes: Current challenges and future perspectives

The urgency of integrating renewable energy sources in the power grid has pushed the development of aqueous metal-ion batteries because of their low cost, nontoxicity, high safety, and environmentally friendliness. Among the variety of aqueous metal-ion batteries that are currently under development, aqueous Zn-ion batteries (A-ZIBs) have recently gained a great attention because of their high specific energy and high reversibility in aqueous solutions, together with the low cost and high abundancy of the zinc. In this article, the authors intend to present an overview of the Prussian blue analogue materials, which are among the most promising materials for positive electrodes in A-ZIBs because of their easier synthesis route, reversible ion-insertion, high safety, and low toxicity, highlighting their strength points and open challenges.     

From lithium-ion to sodium-ion battery

The review discusses the problems of development of sodium-ion batteries intended to replace lithium-ion batteries used in large power plants (electric transport, smart grids). The literature data, mainly for the last five years, devoted to electrode functional materials and electrolytes used in sodium-ion batteries are presented and analyzed.     

A brief review on miniaturized electrochemiluminescence devices: From fabrication to applications

Miniaturized electrochemiluminescence (ECL) systems are widely recognized as a highly detection, user-friendly, and turnkey strategy to develop point-of-care-testing devices. The ECL sensing approach provides numerous advantages over other methods, including high signal-to-noise ratio and measurement with minimal or no background signal. The ECL signal can be easily controlled by a small external potential while providing high sensitivity and decreased electrode fouling, resulting in the use of ECL-based miniaturized systems for detection and monitoring of different analytes, including DNA and bacteria. In this work, different types of miniaturized ECL systems with various fabrication techniques are reviewed and their application in point-of-care-testing is thoroughly discussed. Furthermore, such ECL platforms have been summarized based on the type of the ECL mechanism, electrodes, range of detection, and limit of detection. Finally, some of the upcoming technological interventions to make such a miniaturized ECL platform amenable for portable and on-field analysis have been discussed.     

A stable and high-energy aqueous aluminum based battery

Aqueous aluminum ion batteries (AAIBs) have received growing attention because of their low cost, safe operation, eco-friendliness, and high theoretical capacity. However, one of the biggest challenges for AAIBs is the poor reversibility due to the presence of an oxide layer and the accompanying hydrogen evolution reaction. Herein, we develop a strongly hydrolyzed/polymerized aluminum–iron hybrid electrolyte to improve the electrochemical behavior of AAIBs. On the one hand, the designed electrolyte enables aluminum ion intercalation/deintercalation on the cathode while stable deposition/stripping of aluminium occurs on the anode. On the other hand, the electrolyte contributes to the electrochemical energy storage through an iron redox reaction. These two reactions are parallel and coupled through an Fe–Al alloy on the anode, thus enhancing the reversibility and energy density of AAIBs. As a result, this hybrid-ion battery delivers a specific volumetric capacity of 35 A h L⁻¹ at the current density of 1.0 mA cm⁻², and remarkable stability with a capacity retention of 90% over 500 cycles. Furthermore, the hybrid-ion battery achieves a high energy density of approximately 42 W h L⁻¹ with an average operating voltage of 1.1 V. This green electrolyte for high-energy AAIBs holds promises for large-scale energy storage applications.

A hybrid-ion aqueous aluminium ion battery (HIAAIB) with nickel hexacyanoferrate as the cathode, Al as the anode and a polymerized Al–Fe hybrid electrolyte is reported. During discharge, an Fe–Al alloy forms at the anode, improving performance by relieving corrosion.     

Synthetic paramontroseite VO2 with good aqueous lithium-ion battery performance

Synthetic paramontroseite VO(2) has been successfully obtained using a simple chemical reaction route for the first time after fifty years; the paramontroseite phase shows a conducting property and good aqueous lithium ion battery performance.     

Electrochemical behavior of LiCoO2 as aqueous lithium-ion battery electrodes

Despite the large number of studies on the behavior of LiCoO₂ in organic electrolytes and its recent application as a positive electrode in rechargeable water battery prototypes, a little information is available about the lithium intercalation reaction in this layered compound in aqueous electrolytes. This work shows that LiCoO₂ electrodes can be reversibly cycled in LiNO₃ aqueous electrolytes for tens of cycles at remarkably high rates with impressive values specific capacity higher than 100 mAh/g, and with a coulomb efficiency greater than 99.7%. Stable and reproducible cycling measurements have been made using a simple cell design that can be easily applied to the study of other intercalation materials, assuming that they are stable in water and that their intercalation potential range matches the electrochemical stability window of the aqueous electrolyte. The experimental arrangement uses a three-electrode flooded cell in which another insertion compound acts as a reversible source and sink of lithium ions, i.e., as the counter electrode. A commercial reference electrode is also present. Both the working and the counter electrodes have been prepared as thin layers on a metallic substrate using the procedures typical for the study of electrodes for lithium-ion batteries in organic solvent electrolytes.     

Electroosmotic flow: From microfluidics to nanofluidics

Electroosmotic flow (EOF), a consequence of an imposed electric field onto an electrolyte solution in the tangential direction of a charged surface, has emerged as an important phenomenon in electrokinetic transport at the micro/nanoscale. Because of their ability to efficiently pump liquids in miniaturized systems without incorporating any mechanical parts, electroosmotic methods for fluid pumping have been adopted in versatile applications—from biotechnology to environmental science. To understand the electrokinetic pumping mechanism, it is crucial to identify the role of an ionically polarized layer, the so-called electrical double layer (EDL), which forms in the vicinity of a charged solid–liquid interface, as well as the characteristic length scale of the conducting media. Therefore, in this tutorial review, we summarize the development of electrical double layer models from a historical point of view to elucidate the interplay and configuration of water molecules and ions in the vicinity of a solid–liquid interface. Moreover, we discuss the physicochemical phenomena owing to the interaction of electrical double layer when the characteristic length of the conducting media is decreased from the microscale to the nanoscale. Finally, we highlight the pioneering studies and the most recent works on electro osmotic flow devoted to both theoretical and experimental aspects.     

A non-aqueous Li/organosulfur semi-solid flow battery

A non-aqueous Li/organosulfur semi-solid flow battery is constructed. The battery with a high cell voltage of 3.36 V achieves coulombic efficiency of 99%, voltage efficiency of 73% and energy efficiency of 72% at the current density of 5 mA/cm².     

A brief history of laser-induced breakdown spectroscopy: From the concept of atoms to LIBS 2012

LIBS did not appear de novo in 1962, but was built upon accomplishments of the past. These started with very old concepts of indivisible units (atomos), chemical and physical experiments and theoretical advances that took place in the late 19th and early 20th centuries, the development of the laser, the discovery of gas breakdown, and the realization of the application to spectrochemistry. We sketch the historical developments and focus as well on the advances in LIBS methodology and instrumentation over the past 50 years, culminating with a synopsis of the LIBS 2012 Conference in Luxor, Egypt.     

A Li-O2/CO2 battery

A new gas-utilizing battery using mixed gas of O(2) and CO(2) was developed and proved its very high discharge capacity. The capacity reached three times as much as that of a non-aqueous Li-air (O(2)) battery. The unique point of the battery is expected to be the rapid consumption of superoxide anion radical by CO(2) as well as the slow filling property of the Li(2)CO(3) in the cathode.     

Non-orthogonal micro-free flow electrophoresis: From theory to design concept

Micro-free flow electrophoresis (μFFE) is a technique that facilitates continuous separation of molecules in a shallow channel with a hydrodynamic flow and an electric field at an angle to the flow. We recently developed a general theory of μFFE that suggested that an electric field non-orthogonal to the flow could improve resolution. Here, we used computer modeling to study resolution as a function of the electric field strength and the angle between the electric field and the hydrodynamic flow. In addition we used our general theory of μFFE to investigate other important influences on resolution, which include the velocity of the hydrodynamic flow, the height of the separation channel, and the magnitude and direction of the electroosmotic flow. Finally, we propose four designs that could be used to generate non-orthogonal electric fields and discuss their relative merits.     

MnO2 electrodeposition at the positive electrode of zinc-ion aqueous battery containing Zn2+ and Mn2+ cations

Journal of Solid State Electrochemistry - Effects of MnO2 electrodeposition on α, β, γ, and δ-MnO2 polymorphs from aqueous zinc sulfate solution with manganese sulfate additive...     

A general route to 5-substituted-2-furylacetic acids: a brief synthesis of plakorsin B

3,4-Dihydroxy-5-alkynylcarboxylic acids, readily obtained by the addition of lithium acetylides to α-acetoxysuccinic anhydride followed by reduction and hydrolysis, undergo smooth silver(I)-catalysed 5-endo-dig cyclisations and in situ dehydration to give excellent overall yields of 5-substituted-2-furylacetic acids, including the natural metabolite plakorsin B.     

From synthetic montroseite VOOH to topochemical paramontroseite VO2 and their applications in aqueous lithium ion batteries

Synthetic montroseite VOOH has been successfully prepared via a simple template-free hydrothermal route on a large scale for the first time-after sixty years of delay. The as-obtained sample shows a hierarchical morphology of urchin-like nanoarchitecture with hollow interiors consisting of well-crystalline nanorods standing vertically on the shell surface. Time-dependent experiments illustrated that these hierarchical hollow nanourchins were formed through the hydrolysis-driven Kirkendall effect coupled with a new-phased vanadium oxyhydroxide V(10)O(14)(OH)(2) precursor templated approach. Meanwhile, the as-obtained VOOH hollow nanourchins could convert topochemically to paramontroseite VO(2) without altering the size and original appearance during the annealing process due to the extreme structural similarity revealed by crystal structure analysis. Furthermore, the improved electrochemical performance of both montroseite VOOH and paramontroseite VO(2) hierarchical hollow structures toward Li uptake and release verifies their potential applications as anode materials in aqueous lithium ion batteries. These improved electrochemical properties could be ascribed to the synergetic effect of the microscopic tunneled crystal structure and macroscopic hollow morphological features, which provide the easy infiltration of electrolyte, short diffusion lengths for lithium ions and electron transport as well as sufficient void space to buffer the volume change.     

Ag2V4O11: from primary to secondary battery

Journal of Solid State Electrochemistry - Ag2V4O11 (silver vanadium oxide, SVO) is the positive electrode in primary lithium/SVO batteries that had known an extraordinary success as a power source...