Lithium Iodide Research Articles

Lithium iodide promoted CO2 hydrogenation towards ethanol via biphasic lewis-acid-base pairs synergistic catalysis

Ethanol synthesis via CO2 hydrogenation is of great importance in view of its high-value utilization. Herein, combining with heterogeneous and homogenous catalysis, we have developed an efficient biphasic Lewis-acid-base pairs synergistic catalysis strategy from CO2 hydrogenation. Apart from conventional heterogeneous ethanol synthesis route, it was surprisingly found that LiI homogenous promoter significantly enhanced CO2 conversion, ethanol selectivity, and productivity. LiI promoted CO2 dissolution in pure water and accelerated reaction intermediates consumption, favoring CO2 conversion. In detail, it can weaken C-O bond of CH3OH intermediate through Li+-I- Lewis-acid-base catalysis. The formed CH3I* with lower bond energy for C-I was more facile to dissociate into CH3*, favoring its subsequent coupling with CO* to form ethanol. In combination of Rh1/CeTiOx catalyst, LiI promoter, and methanol as solvent, a record-breaking ethanol yield was achieved (223.1 mmol·g−1·h−1). The obtained ethanol yield was about 18.7 times of that reported the best result in literatures. Especially, the established catalyst system could also be applied for synthesis of higher-carbon-number alcohols by the CO2 hydrogenation with other alcohols solvent (CnH2n+1OH, n = 2,3…).

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The cover image is based on the Article Lithium iodide transport in double gyroid nanochannels formed by zwitterion‐containing solid polymer electrolytes by Karim Aissou et al., https://doi.org/10.1002/pol.20240206. image

High‐Capacity, Long‐Life All‐Solid‐State Lithium–Selenium Batteries Enabled by Lithium Iodide Active Additive

AbstractSelenium (Se) shows promise as a cathode candidate for all‐solid‐state lithium (Li) batteries due to its impressive theoretical volumetric energy density, much higher electronic conductivity, and improved safety in comparison to those for sulfur (S). An active cathode additive, lithium iodide (LiI) is demonstrated, to address the major challenge for all‐solid‐state Li–Se batteries, namely the sluggish redox kinetics resulting from the huge solid‐state conversion barrier. The LiI additive enhances Li+ transport and provides catalytic sites for Se cathode, thus endowing the batteries with accelerated reaction kinetics and extra capacity. DFT calculation and experimental analysis clearly reveal that LiI additive efficiently accelerates the conversion between polyselenide intermediates and Li2Se. With the above advantages, the battery with LiI using Li6PS5Br electrolyte gives an outstanding capacity of 862 mAh gSe−1 beyond the theoretical specific capacity of Se and a superlong life over 1800 cycles at 1C under room temperature. This work offers a simple strategy to facilitate the kinetics of all‐solid‐state Se cathodes and paves the way for the practicality of high‐capacity and long‐life all‐solid‐state Li–Se batteries.

Photochemical Decarboxylative Radical Alkylation/Cyclization Reaction to Fused Nitrogen Heterocycles by LiI/PPh3 Catalysis

Comprehensive SummaryA visible‐light‐induced decarboxylative radical cascade cyclization reaction between N‐(2‐cyanoaryl)‐acrylamides and alkyl N‐(acyloxy)phthalimide (NHPI esters) for the construction of phenanthridine derivatives has been developed. This approach utilizes lithium iodide (LiI) and triphenylphosphine (PPh3) as the redox catalysts and the alkyl radical is produced through the photoactivation of the electron donor‐acceptor (EDA) complex. A series of primary, secondary, and tertiary alkyl‐substituted phenanthridines are prepared in up to 82% yield without transition‐metal catalysts, chemical oxidants, or metal‐/organic dye‐based photocatalysts.

Efficient Direct Recycling of Spent Cathode Materials in Lithium-Ion Batteries

The demand for lithium-ion batteries (LIBs) has surged in recent years, driven by the rapid growth of electric vehicles (EVs) and emerging energy storage technologies. Yet, this surge in demand has also resulted from a significant increase in the number of spent batteries. Given the potential for environment pollution wastage, it is absolutely crucial to prioritize the recovery and recycling of these used lithium-ion batteries.The common techniques employed in large-scale industrial settings for battery recycling are pyrometallurgy and hydrometallurgy. These are pivotal multi-step processes, particularly suitable for materials containing Cobalt (Co) and Nickel (Ni), such as NMC (LiNixMnyCozO2). Aside from NMC, there has been a surge in the adoption of LFP (LiFePO4) as a cathode material target for lithium-ion batteries in electric vehicles worldwide over the past few decades. However, these established industrial recycling methods are not applicable to LFP due to the comparatively lower value of iron. This necessitates the pursuit of direct recycling approaches.In order to accomplish this goal, direct recycling stands out as the most suitable technique for regenerating spent batteries1. Unlike processes involving solution-based or high-temperature steps that entail potentially wasteful steps, thisapproach aims to reduce energy consumption and costs, all while maintaining environmental integrity through a judicious utilization of resources, materials, and energy. Consequently, our attention is directed towards this specific LFP material, prompting us to detail a direct recycling procedure for spent LFP cathodes via a chemical lithiation process at room temperature in a solution containing lithium iodide (LiI) and various solvents2 (Fig. 1).

Room Temperature Efficient Regeneration of Spent LiFePO4 by Direct Chemical Lithiation

The exponential production of lithium-ion batteries for electric vehicles (EVs) and electronic applications leads to the creation of a huge stock of batteries at the end of life. Considering the current economic, geopolitical and environmental context, the recycling of these spent batteries is becoming an urgent need in order to mitigate environmental pollution and limit the waste of valuable and critical resources1.In this work, we report a rewarding direct recycling process of spent LiFePO4 cathode material by direct chemical lithiation in solution2. After safe opening of the spent commercial battery, a structural, morphological, spectroscopic and electrochemical characterization of the spent LFP cathode was carried out to identify the reason(s) of battery failure. The results obtained by XRD (Fig 1a) and Mössbauer spectroscopy (Fig 1b) show that the loss of lithium in the cathode (up to 50%) consumed during formation and growth of the SEI during cycling, is the major reason of the end of life of these batteries, in total agreement with the literature3.To address the lithium shortage problem, a recycling process via direct chemical lithiation in organic solution at room temperature of the LFP cathode has been implemented. Lithium iodide (LiI) dissolved in several solvents such as acetonitrile, cyclohexane, ethanol, DMSO, methanol and propan-1,2-diol was used as both the reductant and the lithiation agent. The best results were obtained with the cathode regenerated in ethanol, which is also the most captivating and environmentally friendly solvent. The different characterizations of this regenerated cathode allow evaluating the efficiency of the regeneration process. Mössbauer spectroscopy (Fig. 2a) confirms the total reduction of FeIIIPO4 to LiFeIIPO4, while electrochemical characterization (Fig. 2b) shows encouraging properties with a reversible capacity of ~168 mAh/g for the regenerated LFP.

Defect-rich carbon nanosheets promoting power density of lithium-ion capacitors in redox electrolyte system

The introduction of redox additives, for example lithium iodide into the catholyte of lithium-ion capacitors can achieve capacity matching between the cathode and anode through the additional capacity provided by the redox reaction. However, the relatively slow redox reaction rate exacerbates the issue of kinetic imbalance between the cathode and anode during charging and discharging process, resulting in reduced coulombic efficiency and power density of lithium-ion capacitors. Herein, we doped carbon nanosheets with NH3 followed by high temperature treatment to obtain carbon nanosheets with rich defects. Theoretical calculations show that defect sites have a mild adsorption effect on iodide. Moreover, the electrochemical evaluation reveals that the defect structure can promote the redox reaction kinetics, thus increasing the electrochemical performance, especially power density of lithium-ion capacitors in the redox electrolyte system.

Regioconvergent Nucleophilic Substitutions with Morita-Baylis-Hillman Fluorides.

Lithium iodide enables regioconvergent C-F bond functionalization of isomeric Morita-Baylis-Hillman fluorides with carbon, sulfur, and nitrogen nucleophiles. The defluorinative carbon-carbon and carbon-heteroatom bond formations give multifunctional compounds in excellent yields and with good to high diastereoselectivities at room temperature. The possibility of catalytic enantioselective allylation is also discussed.

Lithium iodide transport in double gyroid nanochannels formed by zwitterion‐containing solid polymer electrolytes

AbstractThe fabrication of nanostructured block copolymer (BCP) films endowed with lithium ion‐conducting gyroid (GYR) nanochannels is an appealing solution to build solid polymer electrolytes (SPEs) that combines high ionic conductivity (IC) with suitable mechanical properties. However, the formation of a well‐developed GYR structure remains challenging to achieve from the self‐assembly of polyelectrolyte BCP chains. To overcome this issue, large ion conducting gyroid grains were produced within freestanding polystyrene‐block‐poly(2‐vinylpyridine)‐block‐poly(ethylene oxide) (PS‐b‐P2VP‐b‐PEO) films by combining a solvent vapor annealing (SVA) treatment with an infiltration process. Here, the SVA treatment enabled the manufacture of SPEs entirely composed of a GYR structure while the infiltration process allowed for the incorporation of an appropriate Li salt (i.e., lithium iodoacetate, LiIAc) within the 3D‐interconected nanochannels via a Menshutkin reaction. By using this SVA‐Infiltration strategy, it has been demonstrated that the creation of ion conducting GYR nanochannels enhances the ion transportation capacity of pyridine‐containing SPEs since substantially lower ICs were measured from analog PS‐b‐P2VP‐b‐PEO/LiIAc films having a nominally disordered as‐cast state. Remarkably, zwitterionic pyridinium‐based moieties formed inside the interpenetrated nanochannels enable an efficient migration of Li+ and I3− species, leading to an IC as high as 10−4 S cm−1 at 70°C.

Electrochemical Performance of Supercapacitor Using Plasticised Corn Starch Polymer Electrolyte Incorporated with Lithium Iodide

An electrical double-layer capacitor (EDLC) is a supercapacitor type that offers higher energy density and capacitance than an electrolytic capacitor. EDLC bridges the energy or power gap between the batteries, fuel cells, and dielectric capacitors. Most EDLCs are fabricated using electrolytic solutions, many of which are highly corrosive, leading to heavy, bulky, and leaky devices. This research assembled an EDLC employing a plasticised solid polymer electrolyte based on lithium iodide (LiI) doped corn starch. Glycerol was used as the plasticiser. The fabricated EDLC was characterised using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and galvanostatic charge-discharge (GCD) techniques. The specific capacitance obtained from EIS was 1.74 F g–1. By analysing the Nyquist plot obtained from EIS, charge transfer resistance (Rct) and equivalent series resistance (ESR) were determined. CV of the EDLC was carried out at various sweep rates. The highest specific capacitance of 4.66 F g–1 was obtained at a 50 mV s–1 sweep rate. The EDLC was charged and discharged ten times at 1 mA constant current. From GCD, the specific capacitance was found to be in the 4.36 – 5.57 F g-1 range. From these results, starch-LiI-glycerol showed potential as a candidate for electrolyte material for energy device applications.Keywords: Electrolyte, electrical double-layer capacitor, glycerol, lithium iodide, solid polymer, starch, specific capacitance

The art of Lithiation Revisited: Solvent-free room temperature reaction

The lithiation reaction holds immense significance across various branches of chemistry, particularly in the realm of electrochemical energy storage. Here, we report a new method that enables a solvent-free process at room temperature, exhibiting remarkably swift reaction kinetics. Through this process, the chemical integration of Li+ into charged materials based on transition metals is achieved using lithium iodide, LiI. An evident application of this method lies in advancing the direct recycling of cathode materials reclaimed from spent batteries. Notably, the process facilitates the efficient and direct recycling of spent Li(1-x)FePO4 cathode material, sourced from a commercial LIB, without the need for any solvents or heat treatments. The regenerated material exhibits a fully reversible capacity of approximately 168 mAh/g against Li metal, even under high current density conditions, with a consistently stable coulombic efficiency surpassing 99 % over 45 cycles. This regenerative approach holds the potential for seamless extension to other LIB cathode materials, including but not limited to LMFP, LMO, LCO and NMC.

Photoreduction of Trifluoromethyl Group: Lithium Ion Assisted Fluoride-Coupled Electron Transfer from EDA Complex.

Photoinduced single-electron reduction is an efficient method for the mono-selective activation of the C-F bond on a trifluoromethyl group to construct a difluoroalkyl group. We have developed an electron-donor-acceptor (EDA) complex mediated single-electron transfer (EDA-SET) of α,α,α-trifluoromethyl arenes in the presence of lithium salt to give α,α-difluoroalkylarenes. The C-F bond reduction was realized by lithium iodide and triethylamine, two common feedstock reagents. Mechanistic studies revealed the generation of a α,α-difluoromethyl radical by single-electron reduction and defluorination, followed by the radical addition to alkenes. Lithium salt interacted with the fluorine atom to promote the photoinduced reduction mediated by the EDA complex. Computational studies indicated that the lithium-assisted defluorination and the single-electron reduction occurred concertedly. We call this phenomenon fluoride-coupled electron transfer (FCET). FCET is a novel approach to C-F bond activation for the synthesis of organofluorine compounds.

Regenerative Solid Interfaces Enhance High-Performance All-Solid-State Lithium Batteries.

The performance of all-solid-state lithium batteries (ASSLBs) is significantly impacted by lithium interfacial instability, which originates from the dynamic chemical, morphological, and mechanical changes during deep Li plating and stripping. In this study, we introduce a facile approach to generate a conductive and regenerative solid interface, enhancing both the Li interfacial stability and overall cell performance. The regenerative interface is primarily composed of nanosized lithium iodide (nano-LiI), which originates in situ from the adopted solid-state electrolyte (SSE). During cell operation, the nano-LiI interfacial layer can reversibly diffuse back and forth in synchronization with Li plating and stripping. The interface and dynamic process improve the adhesion and Li+ transport between the Li anode and SSE, facilitating uniform Li plating and stripping. As a result, the metallic Li anode operates stably for over 1000 h at high current densities and even under elevated temperatures. By using metallic Li as the anode directly, we demonstrate stable cycling of all-solid-state Li-sulfur batteries for over 250 cycles at an areal capacity of >2 mA h cm-2 and room temperature. This study offers insights into the design of regenerative and Li+-conductive interfaces to tackle solid interfacial challenges for high-performance ASSLBs.

A New Lithium Thioborate–Lithium Iodide Solid-State Electrolyte with High Ionic Conductivity for Lithium Metal Batteries

A New Lithium Thioborate–Lithium Iodide Solid-State Electrolyte with High Ionic Conductivity for Lithium Metal Batteries

Process for Producing Lithium Iodide Cleanly through Electrodialysis Metathesis.

Lithium iodide is commonly used in the production of batteries and drugs. Currently, the neutralization method is the primary means of producing lithium iodide. This method involves using hydriodic acid as a raw material, adding lithium carbonate or lithium hydroxide, and obtaining lithium iodide through evaporation and concentration. However, hydriodic acid is chemically unstable. Its preparation can lead to explosive accidents and encountering high temperatures generates toxic iodine vapors. These limitations restrict its industrial production. The study evaluates the impact of membrane stack configuration, operating voltage, and initial concentrations and volume ratios of reactants on the production process. Electrodialysis metathesis, characterized by a simpler process flow, lower energy consumption, and environmental benefits, emerges as an effective technique for electrically driven membrane separation in lithium salt production and purification. Under the specific conditions of a C-C-A-C-A-C membrane stack configuration, operating voltage at 25 V, initial potassium iodide concentration at 0.4 mol/L, initial lithium sulfate concentration at 0.2 mol/L, and a 1:1 volume ratio of product liquid to raw material liquid, the method achieves a lithium iodide purity of 98.9% with a production cost of approximately 0.502 $/kg LiI.

Surface engineering of Ag3PO4 using lithium iodide for enhanced photocatalytic activity

The surface engineering of Ag3PO4 using lithium iodide was successfully carried out to induce photocatalytic properties. The Ag3PO4 surface was treated using a lithium iodide solution from low to high concentration under stirring and continued with aging. The modified Ag3PO4 samples were characterized using XRD, SEM, BET, UV–Vis DRS, PL spectra, TRPL, Raman spectra, and XPS. LiI treatment on the Ag3PO4 surface decreases a symmetric stretching [PO4] tetrahedron, P/Ag atomic ratio, and FWHM of Ag3d and P2p, and increases the kinetic energy of AgMNN Auger electrons. These phenomena were due to the incorporation of iodine on the Ag3PO4 surface and defect formation on the Ag3PO4 surface. Treatment with a low concentration of LiI solution showed higher photocatalytic activity with a rate constant of 9.05 times faster than samples without LiI treatment. The high photocatalytic activity was due to the suppression of hole and electron recombination, stronger hole species, and high adsorption on the surface of Ag3PO4.

Insights into the LiI Redox Mediation in Aprotic Li-O2 Batteries: Solvation Effects and Singlet Oxygen Evolution.

Lithium-oxygen aprotic batteries (aLOBs) are highly promising next-generation secondary batteries due to their high theoretical energy density. However, the practical implementation of these batteries is hindered by parasitic reactions that negatively impact their reversibility and cycle life. One of the challenges lies in the oxidation of Li2O2, which requires large overpotentials if not catalyzed. To address this issue, redox mediators (RMs) have been proposed to reduce the oxygen evolution reaction (OER) overpotentials. In this study, we focus on a lithium iodide RM and investigate its role on the degradation chemistry and the release of singlet oxygen in aLOBs, in different solvent environments. Specifically, we compare the impact of a polar solvent, dimethyl sulfoxide (DMSO), and a low polarity solvent, tetraglyme (G4). We demonstrate a strong interplay between solvation, degradation, and redox mediation in OER by LiI in aLOBs. The results show that LiI in DMSO-based electrolytes leads to extensive degradation and to 1O2 release, affecting the cell performance, while in G4-based electrolytes, the release of 1O2 appears to be suppressed, resulting in better cyclability.

Preparation of Optically Active 2,2'‐Dibromo‐6,6'‐diiodo‐1,1'‐biphenyl: A Powerful Precursor for Modular Synthesis of Functionalized Atropisomers†

Comprehensive SummaryThe widespread applications of atropisomeric compounds have led to an increasing demand for their synthesis. Rather than synthesizing different functionalized atropisomers individually, an attractive alternative is to identify a key intermediate or precursor that can be readily elaborated and functionalized to realize divergent synthesis of this class of compounds. Building on our previous research on asymmetric ring‐opening of cyclic diaryliodoniums, in this work we developed a copper‐catalyzed enantioselective ring‐opening reaction of ortho,ortho’‐dibromo substituted cyclic diaryliodonium with lithium iodide. The resulting optically active product 2,2'‐dibromo‐6,6'‐diiodo‐1,1'‐biphenyl, possessing two C—Br bonds and two C—I bonds, can be selectively advanced to form different functionalities. Remarkably, the utilities of the product were highlighted by successively demonstrating C—I and C—Br metalation, followed by carboxylation, boroylation, oxygenation, allylation, phosphinylation, etc., all of which provide a new and convenient approach to synthesizing a range of functionalized axially chiral biphenyls.

Enhancing the Mechanical Properties of Poly(vinyl alcohol) Fibers by Lithium Iodide Addition.

The effect of lithium iodide (LiI) on the mechanical strength, properties, and molecular orientation of poly(vinyl alcohol) (PVA) fibers spun by wet spinning and then heat-stretched was studied. The stretchability of LiI-PVA fibers was improved, and the rupture during stretching was suppressed compared to PVA fibers. In addition, the tensile strength and elastic modulus of the thermally stretched fibers have been significantly improved. It was also found that the addition of LiI improves the molecular orientation of PVA. This was achieved because LiI reduced the hydrogen bonds between the molecular chains of PVA, resulting in reduced crystallinity. Most of the LiI in the fiber could be removed by a coagulation bath and washing during the spinning process. This means that LiI is eventually removed, and the heat-treatment strengthens the hydrogen bonds, resulting in excellent mechanical strength.

Understanding the Catalytic Mechanism of Redox Mediators for Li-O2 Batteries Using Cyclic Voltammetry

Lithium-air batteries are appealing candidates for high-energy electric vehicle applications because they have a theoretical capacity 3 to 5 times higher than li-ion batteries. They are composed of a lithium anode and a porous conductive matrix (usually carbon-based), where oxygen is reduced during discharge and oxidized during charge. One of the major issues is the high overpotentials needed to recharge the battery due to the isolating nature of the solid discharge product, lithium peroxide.The use of redox mediators (RMs) for the discharge and charge reactions has gained popularity because it can increase energy efficiency and minimize electrolyte degradation. These molecules act as soluble catalysts: during the discharge, the RM molecule is reduced at the surface of the electrode; it then diffuses through the solution where it can react with solubilized oxygen to form big solid deposits of Li2O2. In the case of charge, the RM is oxidized at the free surface of the electrode that is not blocked by Li2O2, and then chemically reacts with it to release O2. Thus, RMs allow decoupling of the oxygen reduction reaction oxygen evolution reaction from the electron transfer (ET) reactions at the electrode, giving the charge transfer an alternative path to the electrically insulating Li2O2.1 Previous studies have mainly focused on the thermodynamic aspects governing the ability of a molecule to act as a successful RM. The principal parameter analysed is usually the standard potential of the electrochemical couple, although oftentimes it is poorly characterized using inadequate reference electrodes or assumed to be independent of the solvent, Li salt concentration and identity. Some attention has been given to the effect of solvation environments on the potential of iodide,2 but little has been said about other RMs.3 Since most ET reactions with RMs involve a significant change in the charge/size ratio of the molecule or ion, it is only natural that the driving force for this reaction will be dependent on the environment.The kinetics of the ET and of the reaction of RM with the target species (O2 in the case of discharge RM and Li2O2 in the case of charge) is another factor that has received almost no attention, and yet it is crucial for the operation of a Li-O2 battery. Some effort has been made to relate the kinetics of the catalysis to the standard potential of the RM or the ET kinetics,4 but there is no consensus regarding these effects. No rationalization of the effect of solvation environments such as ionic association or DN of the solvent on the kinetics has been established either.Cyclic voltammetry (CV) is a very useful tool to probe the kinetics both of electrochemical reactions and chemical reactions. It is possible to decouple the influence of these two types of processes by varying the scan rate. Furthermore, the effect of ionic association and solvation environment become easily identifiable in CVs. We show how these parameters affect simulated experiments, and how this can facilitate the understanding of the processes limiting the performance of a cell. Moreover, we can use this approach to extract semiquantitative information about the catalytic mechanism both for charge RM and discharge RM by comparing it with experimental data.To benchmark our simulations, the electrochemical behaviour of two typical RMs was studied. 2,5-di-tert-butyl-1,4-benzoquinone (DBBQ) and lithium iodide were used as discharge and charge redox mediator models, respectively. This way, we evidenced the effect of different solvents and of ionic association on CVs, and we showed that the effect of the chemical reaction between triiodide and Li₂O₂ becomes more important at slow scan rates (<1 mV/s). Using this approach, we were able to probe the timescales of the catalytic behaviour of triiodide and relate it to the performance of mediated lithium-oxygen batteries at different charge rates.The advantage of this approach is that it is easily generalizable to other kinds of RMs, without the need of following specific functional groups that depend on the structure of the molecule. This will allow for quantitative information to be obtained about the catalytic behaviour, and aid the understanding of catalytic mechanisms of Li-O2 batteries. Further implementation of this method will be aimed at establishing relationships between the catalytic and the thermodynamic parameters.