Lithium Cations Research Articles

Synchrotron X-ray diffraction in situ study of Li4Ti5O12 synthesis from rutile and anatase

The comparative study of solid state synthesis of Li4Ti5O12 from rutile and anatase as initial reagents was carried out using the method of in situ synchrotron radiation dynamic diffractometry. Initial samples were obtained by mechanical treatment of Li2CO3 and TiO2 (anatase or rutile modifications). It was found that on the first stage an intermediate β-Li2TiO3 phase forms in the reaction system. On further heating the process of formation of the Li4Ti5O12 phase from β-Li2TiO3 and TiO2 is limited by lithium cation diffusion through the β-Li2TiO3 phase. Reaction strongly accelerates at temperatures above 800 oC. Using nano-sized anatase precursor, well-crystallized LTO with smaller grain size may be obtained at lower temperatures.

Ambiguities in solvation free energies from cluster-continuum quasichemical theory: lithium cation in protic and aprotic solvents.

Gibbs free energies for Li+ solvation in water, methanol, acetonitrile, DMSO, dimethylacetamide, dimethoxyethane, dimethylformamide, gamma-butyrolactone, pyridine, and sulfolane have been calculated using the cluster-continuum quasichemical theory. With n independent solvent molecules S initial state forming the "monomer" thermodynamic cycle, Li+ solvation free energies are found to be on average 14 kcal mol-1 more positive compared to those from the "cluster" thermodynamic cycle where the initial state is the cluster Sn. We ascribe the inconsistency between the "monomer" and "cluster" cycles mainly to the incorrectly predicted solvation free energies of solvent clusters Sn from the SMD and CPCM continuum solvation models, which is in line with the earlier study of Bryantsev et al., J. Phys. Chem. B, 2008, 112, 9709-9719. When experimental-based solvation free energies of individual solvent molecules and solvent clusters are employed, the "monomer" and "cluster" cycles result in identical numbers. The best overall agreement with experimental-based "bulk" scale lithium cation solvation free energies was obtained for the "monomer" scale, and we recommend this set of values. We expect that further progress in the field is possible if (i) consensus on the accuracy of experimental reference values is achieved; (ii) the most recent continuum solvation models are properly parameterized for all solute-solvent combinations and become widely accessible for testing.

Another breakthrough in power supply technology – lithium-ion batteries: 2019 Nobel Prize winners in chemistry John Goodenough, Stanley Whittingham and Akira Yoshino

In 2019, the Nobel Prize in Chemistry was awarded to the creators of lithium-ion batteries, who over the past half century have literally revolutionized the battery power supply. The prize was shared equally by American physicist and materials expert John Bannister Goodenough, British-American chemist Michael Stanley Whittingham and Japanese process chemist Akira Yoshino. The operation of lithium-ion batteries is based on the electrochemical oxidation reactions of lithium metal, which is part of the anode. When discharged, lithium is oxidized and its cation moves to the cathode; when charged, under the action of the applied electrical voltage, lithium cations move to the anode, where the recovery occurs. The biographies of the laureates and their main achievements are described briefly. Lithium-ion batteries are produced in huge quantities and have created another breakthrough in energy supply technology.

Development of a methodology for determining major ions in samples of atmospheric particulate matter by ion chromatography

Countless deleterious effects on human health and the environment are promoted by the action of air pollutants. Thus, it is necessary the development of analytical methods to identify and quantify efficiently ions present in atmospheric particulate matter. This study proposes a new analytical methodology for simultaneous quantification of 12 organic ions (Lactate, Acetate, Propionate, Formate, Butyrate, Methanesulfonate, Pyruvate, Monochloroacetate, Trifluoroacetate, Succinate, Oxalate and Citrate), 12 inorganic anions (fluoride, bromate, chloride, nitrite, bromide, nitrate, sulfite, sulfate, tungstade, molybdate, phosphate and chromate) and 7 cations (lithium, sodium, ammonium, potassium, magnesium, calcium and strontium) using ion chromatography coupled to conductivity detection. The optimization of the proposed method was performed univariate and validation was done according to IUPAC recommendations; LOD and LOQ varied between 12 to 114 pg m-3 and 35 to 342 pg m-3 respectively, showing recovery values between 89% to 109% and R2 between 0.9979 and 0.9999 for the 31 main ions studied. Ions were successfully determined in environmental samples of particulate material in the 10 µm and 2.5 µm fractions. This method was considered a comprehensive, accurate, fast and robust procedure for the study of ions in samples of atmospheric particulate matter. DOI: http://dx.doi.org/10.17807/orbital.v12i4.1494

Lithium‐Chelating Resins Functionalized with Oligoethylene Glycols toward Lithium‐Ion Battery Recycling

AbstractRecycling spent lithium‐ion batteries (LIBs) is an important consideration both to preserve metal resources and to reduce hazardous waste. One recycling method is to extract lithium and cobalt ions using organic solvents that contain battery components. However, it is hard to achieve the complete separation of metal ions and this also requires multiple steps. Herein, functionalized polymeric resins are reported, that can capture both lithium and cobalt ions from organic solutions and separate them chromatographically. Specifically, Merrifield resin is functionalized with oligoethylene glycol derivatives, which are structurally similar to crown‐ethers. To test the lithium‐ion depletion, these resins are incubated with bulk solutions of lithium cations at ≈50 ppm in acetonitrile. The results showed 30–45% depletion after filtration in optimal cases. To test this polymer support for chromatographic separation and check the potential for LIB recycling, a column is packed with the functionalized resin beads, and a mixture of lithium (≈200 ppm) and cobalt (≈200 ppm) ions is loaded. The column can achieve baseline separation of these ions and can be used multiple times without degradation. These results suggest that the current solvent extraction steps during recycling processes can be greatly simplified.

Electrochemical synthesis and characterization of poly [Ni(CH3Osalen)] with immobilized poly(styrenesulfonate) anion dopants

Intrinsically conductive polymer poly(N,N′-bis(3-methoxysalicylidene)ethylenediamine nickel(II)) (poly[Ni(CH3Osalen)]:PSS) has been synthesized by electrochemical polymerization from the [Ni(CH3Osalen)] solution containing tetrabutylammonium poly(styrenesulfonate) (TBAPSS). Cyclic voltammetry and in situ EQCM data demonstrated that electrochemical properties of poly[Ni(CH3Osalen)]:PSS are highly dependent on the nature of electrolyte solutions. A wider range of electrochemical activity, higher values of conductance and binary diffusion coefficient in TBAPSS solution are observed than in LiClO4, but the capacity values of films are higher in LiClO4 solution. The introduction of PSS− polyanion during synthesis of polymer film induced cationic mode of charge transport for poly[Ni(CH3Osalen)]. This type of PSS− doped polymers can be used as ion-exchange membranes.The combined electrochemical impedance spectroscopy and in situ conductance measurements on interdigitated electrodes were analyzed using the model concepts of Matthias and Haas, and Einstein relation. This novel approach allowed separating the diffusion coefficient into its ionic and electronic constituents. The ionic diffusion was found to be the limiting factor. Strong association of lithium cation with both the PSS− polyanion and methoxy-groups may be the cause of lower values of diffusion coefficients in LiClO4 solutions. The proposed model is suitable for further studies of similar systems.

Siloxyaluminate and Siloxygallate Complexes as Models for Framework and Partially Hydrolyzed Framework Sites in Zeolites and Zeotypes.

Anionic molecular models for nonhydrolyzed and partially hydrolyzed aluminum and gallium framework sites on silica, M[OSi(OtBu)3 ]4 - and HOM[OSi(OtBu)3 ]3 - (where M=Al or Ga), were synthesized from anionic chlorides Li{M[OSi(OtBu)3 ]3 Cl} in salt metathesis reactions. Sequestration of lithium cations with [12]crown-4 afforded charge-separated ion pairs composed of monomeric anions M[OSi(OtBu)3 ]4 - with outer-sphere [([12]crown-4)2 Li]+ cations, and hydroxides {HOM[OSi(OtBu)3 ]3 } with pendant [([12]crown-4)Li]+ cations. These molecular models were characterized by single-crystal X-ray diffraction, vibrational spectroscopy, mass spectrometry and NMR spectroscopy. Upon treatment of monomeric [([12]crown-4)Li]{HOM[OSi(OtBu)3 ]3 } complexes with benzyl alcohol, benzyloxide complexes were formed, modeling a possible pathway for the formation of active sites for Meerwin-Ponndorf-Verley (MPV) transfer hydrogenations with Al/Ga-doped silica catalysts.

Towards the intercalation of Li cations to the Co(II) and Mn(II) ferrocenyl-phosphinic MOFs

A possibility to use the Co(II) and Mn(II) metal-organic frameworks (MOFs) with ferrocenyl-phosphinic ligands for storage of lithium cations is analyzed quantum chemically. Ferrocenyl (Fc) moieties are regarded as the most probable site of Li+ location. The effect of phosphinate group on the Li-Fc interaction energies has been evaluated. Similarly to the case of unsubstituted Fc, the most energetically advantageous position of Li+ for ferrocenyl-phosphinic acid is found near cyclopentadienyl ring. For the binuclear models of MOFs Li+-MOFs interaction energies have been estimated. It is shown that reduced Mn(I) and Co(I) MOFs can accommodate one lithium per one Mn or Co ion without destruction, that opens the perspective of using the MOFs under study as electrode materials in LIBs.

Improvement on Electrochemical Performance and Safety Using Mixtures of Ionic Liquid and Conventional Organic Electrolyte for Sodium-Ion Batteries

The success of commercializing sodium-ion batteries is inhibited by the implementation of suitable electrolytes that have economic feasibility and stable electrochemical performance. Organic electrolytes such as Na[ClO4]- or Na[PF6]-including organic solvents, EC, PC, DMC, and DEC, are most widely used to investigate the performance of sodium-ion batteries. These electrolytes are widely accepted because of the analogous studies in LIBs, but their flammability can cause reliability issues. Moreover, the SEI layer composed of sodium cations is known to be inhomogeneous and fragile, giving a higher solubility than that based on lithium cations.(1) In this regard, ionic liquid electrolytes are a drawing huge attention to constructing safe electrochemical devices owing to their unique properties such as low volatility and low flammability. Furthermore, recent studies report ionic liquids show similar electrochemical performance at room temperature to organic electrolytes and better interfacial properties.(2-4) Despite this bright improvement, the cost of ionic liquids drags down the advantage of economical sodium-ion batteries.In this study, ionic liquid and organic liquid electrolytes are mixed to adjust the balance of cost, performance, and safety. The [C3C1pyrr][FSA] (C3C1pyrr+ = N-methyl-N-propylpyrrolidinium) ionic liquid and PC organic solvent are used as mother electrolytes with Na[FSA] (FSA = bis(fluorosulfonyl)amide) and Na[ClO4] salts. The physical and electrochemical properties of the various mixing ratio of those mixture electrolytes are investigated for sodium-ion batteries. These mixture electrolytes improve not only flammability but also show better rate and cycling performance. The detailed electrochemical properties are evaluated by comparing reference electrolytes to clarify the dual salts effect and dual solvents (ionic liquids and organic solvent) effect. This performance will be discussed based on half cell tests using a Na2FeP2O7 positive electrode and full cell tests using a hard carbon negative electrode and a NaCrO2 positive electrode.

Slow Growth Approach for Lithium Ion Deposition on Lithium Metal Anode Surfaces

Lithium metal anodes are indispensable for next-generation batteries including Lithium-Sulfur and Lithium-air batteries which show high promise for electric vehicles and other energy storage applications. Challenges such as extreme reactivity and lithium dendrite formation have kept lithium metal anodes away from practical applications. Lithium dendrite formation on anode surfaces during the charging process originates from the inhomogeneous deposition of metallic lithium during the electrochemical reduction of lithium cations. However, the underlying mechanisms of Li ion deposition from the electrolyte solution onto the anode surface are still poorly understood due to its inherent complexity. In this work, Density Functional Theory (DFT) simulations and thermodynamic integration calculations are conducted to study the electron and ion transfer between lithium metal slab and the electrolyte in absence of an external field. The slow growth approach allow the energy barriers on the diffusion and deposition pathway to be studied. This method illuminate the underlying mechanisms on lithium-ion deposition and provide a better understanding of the early stages of dendrite nucleation. We explore the effect of the solvent chemistry and structure, distance of the solvated complex from the surface, anion-cation separation, and concentration of Li-salts on the deposition of lithium ions from the electrolyte phase onto the surface. It is found that the structure and properties of the solvation shell around the lithium cation has a great influence on the ability of the cation to diffuse as well as on its surrounding electron environment.

Single-Ion Conductor Polymer Electrolytes for All Solid-State Batteries

Poly(ethylene oxide) (PEO) can be considered the most widely studied and applied, all solid-state (solvent free) polymeric lithium ion conductor.1 However, the material suffers from numerous drawbacks: most importantly, PEO shows a considerable tendency towards crystallization.2 Consequently, linear PEO shows a drastic increase in ionic conductivity above its melting temperature, typically ranging between 40 and 60 °C depending on the molecular weight. This temperature-dependence strongly impedes the commercial application of PEO as substitute for the state-of-the-art liquid, flammable carbonate electrolytes of today’s lithium ion batteries. One major benefit of solid (polymer) electrolytes lies in their high mechanical stiffness along with shape-flexibility and elasticity, which could be used to avoid spacer membranes. This could not only increase the specific capacity of the cell by weight reduction and decreased electrode distance but also impede lithium dendrite growth at the electrode interfaces.Many reports find that LiTFSI in combination with PEO delivers among the highest ionic conductivities for solid polymer electrolytes. The combination of the small Li+ cation and the bulky, highly charge-delocalized TFSI- anion leads to a very weakly associated salt structure. The TFSI- anion contributes up to 80 % to the ionic conductivity in typical PEO/LiTFSI mixtures by propagating through the electrolyte.3 However, TFSI- cannot be converted nor intercalated electrochemically at the electrodes in a battery application. During discharge, anions accumulate at the anode in opposite direction to the internal electric field, depolarizing the cell and thereby diminishing its specific capacity and power. Furthermore, the high concentration of anions at either electrode can facilitate the growth of unwanted lithium dendrites at the surface. The concept of a single-ion conducting electrolyte tackles these issues by spatially fixating the anions onto a scaffold, e.g. a polymer backbone. This restricts the anion movement and helps to increase the percentage of current transported only by lithium cations, which is referred to as the lithium transport number tLi+ .A synthetic approach to combine the lithium ion coordinating chemistry of a PEO-based polymer with a sterically frustrated chain architecture can be found in brush-like graft copolymers.4 We recently presented a convenient two-step pathway for the synthesis of clickable PEO-based electrolyte materials.5 In the first step, epoxy- as well as alkyne-functionalized glycidyl propargyl ether (GPE) is directly converted to P(GPE) by monomer-activated, anionic ring-opening polymerization (AROP, fig. a). We showed the consequent functionalization of this versatile polymer backbone in the second step by copper(I)-catalyzed alkyne-azide cycloaddition (CuAAC, Click-chemistry) under very mild conditions and with complete removal of copper catalyst traces. We could tailor the polymer composition by the sequential addition of the corresponding, azide-equipped side-groups; in our case tri(ethylene glycol) azide (EG3-N3) and benzyl azide (Bn-N3) and a specially synthesized, clickable lithium bis(trifluoromethanesulfonyl)imide azide (LiTFSI-N3) which integrates the concept of single-ion conduction (fig. a,b)As an improved version of the previously presented, sequentially clicked graft copolymers, we prepared single-ion conducting P[GPE-(EG3x-ran-LiTFSIy)]100 electrolytes (fig. c) by clicking EG3-N3 as well as LiTFSI-N3 sidegroups onto the P(GPE) backbone with different amounts of lithium salt in the structure.6 We analyzed these materials in terms of composition (NMR, SEC), temperature behavior (TGA, DSC) as well as applicability as lithium ion conducting electrolytes (ionic conductivity, lithium transport number, cyclovoltammetry, battery cycling and extended DRT analysis). Additionally, we synthesized the fully EG3-grafted P(GPE-EG3)100(fig. d) as a matrix polymer and mixed it with LiTFSI to obtain a salt-in-polymer electrolyte as comparison dual-ion system. Both the type of lithium salt as well as the ion-conducting matrix are the same in both electrolytes, but a significantly increased lithium transport number is expected for the single-ion conductor. Herein we present two solid polymer electrolyte systems based on the versatile P(GPE) backbone – one of them single-ion conducting – and compare them in a detailed and fundamental study.References(1) Armand, M. Solid State Ionics 1983, 9-10, 745–754. DOI: 10.1016/0167-2738(83)90083-8.(2) Berthier, C.; Gorecki, W.; Minier, M.; Armand, M. B.; Chabagno, J. M.; Rigaud, P. Solid State Ionics 1983, 11 (1), 91–95. DOI: 10.1016/0167-2738(83)90068-1.(3) Bouchet, R.; Maria, S.; Meziane, R.; Aboulaich, A.; Lienafa, L.; Bonnet, J.-P.; Phan, T. N. T.; Bertin, D.; Gigmes, D.; Devaux, D.; Denoyel, R.; Armand, M. Nature materials 2013, 12 (5), 452–457. DOI: 10.1038/NMAT3602.(4) Nishimoto, A.; Watanabe, M.; Ikeda, Y.; Kohjiya, S. Electrochimica Acta 1998, 43 (10-11), 1177–1184. DOI: 10.1016/S0013-4686(97)10017-2.(5) Krimalowski, A.; Thelakkat, M. Macromolecules 2019, 52 (11), 4042–4051. DOI: 10.1021/acs.macromol.9b00206.(6) Hahn, M.; Rosenbach, D.; Krimalowski, A.; Nazarenus, T.; Moos, R.; Thelakkat, M.; Danzer, M. A. Electrochimica Acta 2020, 136060. DOI: 10.1016/j.electacta.2020.136060. Figure 1

Overview on Lithium-Ion Battery 3D-Printing By Means of Material Extrusion

In parallel with the considerable investigations on renewable energy sources, electrical energy storage systems used to store the energy produced now and to provide it when needed have received much attention lately.1 Amongst them, lithium-ion batteries (LIB) are today the most employed in a huge range of purposes including cellphones, laptops or even electric vehicles. Current LIB consists in a planar arrangement (2D) in which the different parts of the battery (positive and negative electrodes, separator, current collectors) are rolled or stacked. Unfortunately, in this type of 2D configuration, lithium ions diffuse only along one dimension. Additive manufacturing (AM) technologies, also called 3D-printing processes, could enable the production of much more complex 3D architectures thus allowing diffusion of the lithium cations towards two or three-dimensions. Advantage of those 3D designs is that the electrochemical active surface area is expected to increase as well as the battery specific capacity and power.2 On the other hand, AM could also allow the direct incorporation of LIB within the final object, thus enabling the possibility to maximize the energy storage capabilities while reducing the dead volume and weight.Amongst the various AM available technologies, we focused our work on the Fused Deposition Modeling (FDM) process using a thermoplastic filament as material source for the 3D-printer. In this presentation, the formulation of composite PLA-based filaments specially designed to print each parts of the LIB (with liquid electrolyte) will be described.3,4 The active material composition within the negative and positive electrodes (graphite and lithium iron phosphate (LiFePO4) respectively), was increased as high as possible in order to enhance the electrochemical performances. Furthermore, the addition of a plasticizer was required to maintain enough mechanical strength while, in the meantime, carbon black was added to confer adequate electrical properties. The impact of ceramic additives on ionic conductivity in the separator was also investigated. From the optimized filaments compositions, stepwise and then “one-shot” 3D-printing of complete LiFePO4/graphite battery cells of any shapes were carried out (Figure 1). In order to prevent short-circuits, classical 3D-printing parameters such as the infill patterns and infill density were investigated for the LIB separator improvement.Finally, this presentation will introduce our latest results5 regarding the printability of a polyethylene oxide/lithium bis(trifluoromethanesulfonyl)imide (PEO/LiTFSI) filament (2.18 × 10−3 S cm−1 at 90 °C) optimized to be used as solid polymer electrolyte in a lithium-ion battery.This presentation, by combining both battery and 3D-printing understandings, will tackle various electrochemical (thickness, electronic and ionic conductivity, liquid electrolyte uptake) and 3D-printing parameters (infill density, infill pattern, perimeters, over and under-extrusion, retraction), which clearly paves the way for enhanced 3D-printed LIB.

A New Glass Forming Electrolyte Based on Lithium Glycerolate

The study of the interplay between structure and conductivity in lithium-conducting electrolytes is a pivotal point for the development of future secondary batteries [1]. The use of Glycerol as a low molecular weight component in electrolytes is particularly interesting due to its glass-forming behavior and low glass transition temperature (-78.5°C). In addition, a high flexibility of the alkyl backbone chain and the well-known capability of oxygen functionalities to coordinate lithium cations make Glycerol very appealing as ion-conducting media as well as building block to obtain hybrid polymer electrolytes [2].On this basis a family of eleven electrolytes based on Lithium Glycerolate with general formula C3H8-xO3Lix, where 0 ≤ x ≤ 1, is prepared and investigated [3]. In these electrolytes the Glycerolate (C3H8-xO3 x-) component acts as a large and flexible macro-anion which is able to provide a high single-ion conductivity to the material (8.36∙10-5 S∙cm-1 at 20°C and 1.55∙10-2 S∙cm-1 at 150°C for x = 0.25).Finally, the Glycerol∙∙∙Li+ interactions in these electrolytes are studied on T and x, with a particular reference to the detection of: a) macro-anion coordination sites; and b) the secondary structure of Glycerol chains. Insights on the long-range charge transfer mechanism and Glycerol relaxation events are also discussed.These studies are carried out by Inductively-Coupled Plasma Atomic Emission Spectroscopy, IR and Raman spectroscopies, DSC, TGA, and Broadband Electrical Spectroscopy.

Ionic Transport Properties in Sulfone-Based Solid Polymer Electrolytes

Solid polymer electrolytes (SPEs) consist of polymers and metal salts, which are safer than liquid electrolytes owing to non-leakage of electrolytes. They have many practical advantages compared with inorganic solid electrolytes; for instance, flexibility and processability. However, SPEs have several challenges: low ionic conductivity and Li+ transference number. Typical SPEs such as a polyethylene oxide (PEO)-based electrolyte show low ionic conductivity of ~10−5 S cm−1 and low Li+ transference number of ~ 0.2 at room temperature 1, 2. Therefore, it is essential to design novel SPEs with high ionic conductivity and Li+ transference number for practical battery applications.Recently, our group has focused on highly concentrated liquid electrolytes and found that sulfolane (SL)-based molten Li salt solvates show high Li+ transference number (0.7 ~ 0.8) via Li+ hopping/exchange conduction mechanism 3. In the SL-based electrolytes, oxygen atoms of the sulfone groups coordinate to two different neighbouring lithium cations to form a unique chain-like Li+ coordination structure, which enables predominant Li+ hopping/exchange conduction between the coordination sites. This was considered to accelerate Li+ transport and result in the high Li+ transference number despite relatively high viscosity of the electrolytes.Here, we expect that high Li+ transference number can be achieved in SPEs containing the sulfone moieties similar to the SL-based molten Li salt solvates. In this study, we attempted to incorporate the sulfone groups into the polymer side chains to achieve high Li+ transference number. Thermal, ionic transport and electrochemical properties of the prepared sulfone-based SPEs were investigated. We synthesised poly(3-acryloyl sulfolane) (PASL) containing the sulfone groups into the side chains of polyacrylates as polymer matrix of SPEs and prepared two types of SPEs: Li[TFSA] (lithium bis(trifluoromethanesulfonyl)amide)/PASL = 1:2 and Li[TFSA]/PASL/SL = 1:1:1. Li[TFSA]/PASL was prepared by mixing Li[TFSA] and PASL at a molar ratio of 1:2 using DMF (N,N-dimethylformamide) as co-solvent followed by vacuum drying for five days. Li[TFSA]/PASL/SL was prepared by mixing equimolar amounts of Li[TFSA], PASL and SL.In addition to ionic conductivity, we have also evaluated Li+ transference number in these electrolytes by the potentiostatic polarization method using a Li metal symmetric cell. 4, 5 As shown in Figure (a), ionic conductivity of Li[TFSA]/PASL/SL is higher than that of Li[TFSA]/PASL. The plasticization of the SPE in the presence of SL molecules resulted in the higher ionic mobility for Li[TFSA]/PASL/SL. The ionic conductivity of Li[TFSA]/PASL at the glass transition temperature (T g : 45 °C) was 3.9×10−8 S cm−1 and that of Li[TFSA]/PASL/SL(T g : −45 °C) was 1.7×10−14 S cm−1. The ionic conductivity at T g of Li[TFSA]/PASL is much higher than that of PEO-based polymer electrolytes of about 10−14 S cm−1 as well as that of Li[TFSA]/PASL/SL. Ionic conduction behavior in SPEs can be discussed in terms of coupling/decoupling of Li+ conduction with/from polymer segmental motions 1. In the coupling system, ionic motions are coupled with the segmental motions of polymer chains and therefore ionic conductivity becomes very low at T g (~10−14 S cm−1). On the other hand, in the decoupling system, the ionic motions is decoupled from the polymeric motions, and ionic conductivity at T g is higher than that in the coupling system. Whilst Li+ conduction is dominated by the polymeric segmental motions in PEO-based electrolytes, Li[TFSA]/PASL can be classified as the decoupling system owing to its much higher ionic conductivity at T g of ~10−8 S cm−1. Li+ transference number of Li[TFSA]/PASL/SL was found to 0.75 at 80 °C, which is higher than that of PEO-based polymer electrolytes (t Li = 0.2 at 70 °C). This suggests that the unique Li+ hopping/exchange mechanism contributes to ionic conduction in the solfone-containing SPE as well as a SL-based molten Li salt solvates.References Seki et al., J. Phys. Chem. B 2005, 109, 3886-3892.Rosenbach, et al., ACS Appl. Energy Mater. 2019, 2, 3373-3388Dokko et al., J. Phys. Chem. B, 2018, 122, 47, 10736-10745.G. Bruce et al., Solid State Ionics, 1988, 28-30, 918-922.Watanabe et al., Solid State Ionics, 1988, 28-30, 911-917. Figure 1

Novel Bulky Lithium Salts and Their Electrolytes for Safer Solid-State Lithium Metal Battery

In recent years, Lithium metal batteries (LMBs) have gained great interests thanks to their high capacity that can respond to the continuous increasing need for energy storage and device. The design and development of new solid-state electrolytes e.g. polymer based ones (SPEs) then became crucial towards intrinsically safer LMBs. A successful electrolyte candidate needs to fulfill several requirements such as high transference number (tLi +) and a compromise between two antagonist properties: conductivity and mechanical properties. Most researches focused on the synthesis of single-ion conducting electrolytes as a strategy to overcome these difficulties1,2. However, these materials often require complicated and delicate chemistry and their conductivity often remains low (σ < 10-5 S/cm at 60°C). An alternative promising route that received much less attention is the development of bulky Lithium salts with macroanion. The bulky anion reduces ion paring and salts aggregation and present negligible mobility compared to Lithium cation resulting in higher transference number3.In this work, we present a new macroanion based on Polyhedral Oligomeric Silsesquioxane (POSS) grafted with either polyethylene oxide oligomers (PEG) and/or Lithium sulfonyl (trifluoromethanesulfonyl) imide (LiTFSI) denoted as POSS-LiTFSI-PEG or POSS-LiTFSI respectively. Thus, SPE has been prepared with a reference high molecular weight polyethylene oxide at different OE/Li ratio from 10 to 25. This new concept of bulky multi-anion based on TFSI moieties allows a complete salt dissociation, an enhancement of the mechanical properties thanks to the presence of the inorganic POSS multi anions that play the role of nano fillers, and finally, a strong increase of the Li+ transference number (tLi+>0,55), which opens many perspectives. The cycling performance obtained in both Lithium symmetric cells and LMBs prototypes will be also presented.References(1) Bouchet, R.; Maria, S.; Meziane, R.; Aboulaich, A.; Lienafa, L.; Bonnet, J.-P. P.; Phan, T. N. T.; Bertin, D.; Gigmes, D.; Devaux, D.; et al. Single-Ion BAB Triblock Copolymers as Highly Efficient Electrolytes for Lithium-Metal Batteries. Nat. Mater. 2013, 12 (5), 452–457.(2) Zhang, H.; Li, C.; Piszcz, M.; Coya, E.; Rojo, T.; Rodriguez-Martinez, L. M.; Armand, M.; Zhou, Z. Single Lithium-Ion Conducting Solid Polymer Electrolytes: Advances and Perspectives. Chem. Soc. Rev. 2017, 46 (3), 797–815.(3) Chinnam, P. R.; Wunder, S. L. Polyoctahedral Silsesquioxane-Nanoparticle Electrolytes for Lithium Batteries: POSS-Lithium Salts and POSS-PEGs. Chem. Mater. 2011, 23 (23), 5111–5121. Figure 1

Carbon species solvated in molten carbonate electrolyser cell from first-principles simulations

We study the solvation of molecules and ions that are key in the context of molten carbonate electrolyser cells using first-principles simulations. Focusing on the electroreduction of CO2 to CO in a molten carbonate medium, we investigate the solvation of both the reactant CO2 and the product CO in the eutectic LiKCO3 (containing 62% Li2CO3, 38% K2CO3). CO2 is found to spontaneously react with the carbonate ions to form the transient pyrocarbonate species, C2O52−. To investigate the similar reaction that could occur with CO and CO32− to form an oxalate, we simulated that species and found it to be stable in the melt, supporting this hypothesis. We further present the solvation of O2−, finding that it shows preferential formation of a complex with four lithium cations. Estimates of the diffusion coefficients of these species are then reported, showing that CO has the faster diffusion of all the molecules and ions studied.

New understanding of the role of lithium nitrate additivesin lithium-sulfur batteries

Lithium-sulfur (Li-S) batteries are considered to be one of the next-generation battery candidates and have been widely studied. Despite the obvious advantages of Li-S batteries, there are still many serious problems with sulfur electrode: The active material sulfur (S) and the final product lithium sulfide (Li2S) are both insulators, and the electronic conductivity is poor, so that a large amount of conductive agent must be added to the sulfur electrode; the large difference in density between S and Li2S makes the electrode undergo a huge volume change (about 80%) during the charge and discharge process, which easily leads to the collapse of the sulfur electrode structure, which leads to the degradation of the Li-S batteries performance; the lithium polysulfide produced during charge and discharge has extremely high solubility in ether electrolytes, resulting in the “shuttle effect”. Especially, the “shuttle effect” of lithium polysulfide has caused problems such as poor battery cycle performance, rapid capacity decay and overcharge, which severely restricted the further development and commercial application of Li-S batteries. As a key component of Li-S batteries, electrolyte not only plays a role in transmitting lithium cation (Li+) and conducting internal circuits, but also one of the main factors that determine the overall performance of the battery capacity and cycle stability. Lithium nitrate (LiNO3) has received widespread attention as an electrolyte additive for Li-S batteries, and its mechanism of action has also been studied in depth. However, this article provides a new understanding of the mechanism of LiNO3 additives through deep study and new experimental schemes. In this experimental scheme, the Li metal anode recycled by electrolyte containing LiNO3 additive and fresh sulfur electrode was used to reassemble the battery with the electrolyte without the LiNO3 additive; the sulfur electrode recycled by electrolyte containing LiNO3 additive and fresh Li metal anod were used to reassemble the battery with the electrolyte without the LiNO3 additive; both batteries have serious overcharging during the charging process, and the shuttle of polysulfide anions occurs. This shows that the mechanism of LiNO3 inhibiting the “shuttle effect” is not just to form SEI film. Through the ion migration number test, it is found that after adding LiNO3 additive, the migration number of Li+ increases, resulting in a significant decrease in the migration of polysulfide anions. It can be concluded that another effect of adding LiNO3 additives is to increase the migration number of Li+, thereby reducing the migration number of anions and effectively inhibiting the “shuttle effect”. At present, the components of gunpowder (sulfur, nitrate, carbon) are concentrated in Li-S batteries, which may be potentially dangerous during commercial use. According to the new discovery of the role of LiNO3 additives in Li-S batteries in this work, future research work can be based on the migration number theory to find other electrolyte additives that can promote the migration number of lithium ions and interact with polysulfide anions. LiNO3 additives, thereby reducing the potential dangers of Li-S batteries in use.

Synthesis, structural characterization and antitumoral activity of (NH4)4Li2V10O28.10H2O compound

The decavanadate compound with inorganic cations, (NH4)4Li2V10O28.10H2O, was synthesized by slow evaporation from aqueous solution. It was characterized by Infrared (IR) spectroscopy, Scanning Electron Microscopy (SEM) with Energy Dispersive X-Ray Analysis (EDX) as well as thermal analysis such as Differential Scanning Calorimetry (DSC), differential thermal analysis (DTA) and thermogravimetry (TG). The formula unit consists of one decavanadate cluster [V10O28]6−, two lithium cations, four ammonium ions and ten water molecules. In the crystal, molecules are linked into a three-dimensional network by O-H…O and N-H…O hydrogen bonds. The prevalence of these intermolecular interactions was confirmed by an analysis of the Hirshfeld surface (HS) and fingerprint plots (FP). The relative contribution of different interactions to the HS indicates that the O…H/H…O and H…H contacts account 86.8% of the total HS area. In this study, the cytotoxic and the antiproliferative activities of (NH4)4Li2V10O28.10H2O on human cancer cells (U87, IGR39 and MDA-MB-231) were investigated. This compound demonstrated dose-dependent antiproliferative activity on U87, MDA-MB-231 and IGR39 with IC50 values of 2 µg/mL, 18 µg/mL and 12 µg /mL, respectively. These data provide evidence on the potential anticancer activity of (NH4)4Li2V10O28.10H2O.

Structural and Ion Dynamics in Fluorine-Free Oligoether Carboxylate Ionic Liquid-Based Electrolytes.

Here, we investigate the physicochemical and electrochemical properties of fluorine-free ionic liquid (IL)-based electrolytes with two different cations, tetrabutylphosphonium, (P4,4,4,4)+, and tetrabutylammonium, (N4,4,4,4)+, coupled to a new anion, 2-[2-(2-methoxyethoxy)ethoxy]acetate anion (MEEA)−, for both neat and (P4,4,4,4)(MEEA) also doped with 10–40 mol % of Li(MEEA). We find relatively weaker cation–anion interactions in (P4,4,4,4)(MEEA) than in (N4,4,4,4)(MEEA), and for both ILs, the structural flexibility of the oligoether functionality in the anion results in low glass transition temperatures, also for the electrolytes made. The pulsed field gradient nuclear magnetic resonance (PFG NMR) data suggest faster diffusion of the (MEEA)− anion than (P4,4,4,4)+ cation in the neat IL, but the addition of a Li salt results in slightly lower mobility of the former than the latter and lower ionic conductivity. This agrees with the combined 7Li NMR and attenuated total reflection–Fourier transform infrared (ATR–FTIR) spectroscopy data, which unambiguously reveal preferential interactions between the lithium cations and the carboxylate groups of the IL anions, which also increased as a function of the lithium salt concentration. In total, these systems provide a stepping stone for further design of fluorine-free and low glass transition temperature IL-based electrolytes and also stress how crucial it is to control the strength of ion–ion interactions.

Polymer–Ceramic Composite Electrolytes for Lithium Batteries: A Comparison between the Single-Ion-Conducting Polymer Matrix and Its Counterpart

Single-ion-conducting polymer electrolytes are attractive to use in lithium batteries as the transference number of the lithium cation approaches unity. This helps prevent concentration gradients a...