Search

International audience; Interfaces and their understanding/control are the key to pave the way for the development of solid-state batteries. This work focuses on the development of operando Auger cycling using an electron beam to investigate the Li/solid electrolyte (SE) interphases. To do so, the fully tunable electron gun of the Auger was applied on top of a model Li/Li6PS5Cl(Arg) stack, allowing charge build up at the Arg surface and Li+ migration from the lithium electrode followed by SE interphase formation and Li plating. Overall, it is found that (i) Li6PS5Cl is first reduced to Li2S, LiCl and Li3P while (ii) Li plating occurs almost concomitantly and (iii) proceeds until the end of the operando cycling. These results were then confirmed by operando XPS using an electron beam. Importantly, this study highlights that operando Auger is more powerful than operando XPS as it provides visual observation of the dynamics/morphology of both Li/solid electrolyte interphase formation and Li plating together with reliable chemical information. This study thus opens the door for future development of operando Auger cycling using an electron beam as a powerful approach to better understand the interfaces in solid-state batteries.

Makale, WOS:000917577100001, Garnet-type solid-state electrolytes are promising candidates for solid-state lithium batteries, nevertheless their ionic conductivity is still not enough for commercial applications. On the other hand, doping still is the common way to improve the ionic conductivities of these solid electrolytes. In this study, mono and dual-doped garnet-type solid electrolytes were synthesised by substituting indium (In), gallium (Ga), indium-titanium (In-Ti) and gallium-titanium (Ga-Ti) to the Li7La3Zr2O12 structure by a solid-state reaction method. The contribution of substitutions to the formation of crystal phases was investigated by X-ray diffraction (XRD) and X-ray absorption spectroscopy (XAS). On the other hand, morphological analyses were done by scanning electron microscope (SEM) and the ionic conductivities of the solid electrolytes were determined by electrochemical impedance spectroscopy (EIS). The study showed that while Li7-3xInxLa3Zr2O12 (for x = 0.05, 0.10, 0.15, 0.20) and Li7-3xGaxLa3Zr2O12 (for x = 0.05) samples were formed in tetragonal phase with a space group of I41/acd:2, dual substituted Li7-3xInxLa3Zr1.8Ti0.2O12 and Li7-3xGaxLa3Zr1.8Ti0.2O12 solid electrolytes for all x values were formed in cubic phase with a space group of I-43d. The highest conductivity is reached for Li6.85Ga0.05La3Zr1.8Ti0.2O12. The radial distribution function studies showed that when more In and Ga atoms take place in the sites of Li atoms, more O atoms take place in the vicinity of both substituted In and Ga atoms within the Li7La3Zr1.8Ti0.2O12 (LLZTO) crystal framework which can eventuate in a change in the conduction mechanism., Scientific Research Projects (BAP) Coordination Unit of Selcuk University

The use of composites instead of pure metals as negative electrodes is an alternative strategy for making all-solid-state lithium-ion batteries (Li-SSBs) more viable. This study reports on the properties of a composite electrode (Sn/Graphite) consisting of nanosized Sn (17 wt %) and graphite (83 wt %). The theoretical capacity of this material is 478 mAh g(Sn/Graphite)–1. When mixed with Li3PS4 (LPS) as a solid electrolyte (SE), an areal capacity of 1.75 mAh cm–2 (active mass loading of 3.8 mg cm–2) is obtained, which can be increased up to 3.0 mAh cm–2 for 7.6 mg cm–2. At 0.02 mA cm–2, the Sn/Graphite electrode delivers a gravimetric capacity of 470 mAh g(Sn/Graphite)–1, i.e., close to its theoretical value. At 0.1 mA cm–2, the capacity is 330 mAh g–1 (second cycle) but drops to 84 mAh g–1 after 100 cycles. Solid-state nuclear magnetic resonance spectroscopy (ssNMR) and X-ray photoelectron spectroscopy (XPS) are used to investigate the stability of the solid electrolyte for this cell configuration. Optimization of the electrode is explored by varying the electrode loading between 3.8 and 7.6 mg cm–2 and the SE content between 0 and 65%. For electrodes without any SE, gravimetric capacities (mAh g(Sn/Graphite)–1) and areal capacities (mAh cm–2) are lower compared to electrodes with SE; however, their volumetric capacity is higher. This emphasizes the need to optimize the composition of electrodes for SSBs.

Protonic ceramic fuel cells (PCFCs) offer a convenient means for electrochemical conversion of chemical energy into electricity at intermediate temperatures with very high efficiency. Although BaCeO3- and BaZrO3-based complex oxides have been positioned as the most promising PCFC electrolytes, the design of new protonic conductors with improved properties is of paramount importance. Within the present work, we studied transport properties of scandium-doped barium stannate (Sc-doped BaSnO3). Our analysis included the fabrication of porous and dense BaSn1−xScxO3−δ ceramic materials (0 ⩽ x ⩽ 0.37), as well as a comprehensive analysis of their total, ionic, and electronic conductivities across all the experimental conditions realized under the PCFC operation: both air and hydrogen atmospheres with various water vapor partial pressures (p(H2O)), and a temperature range of 500–900 °C. This work reports on electrolyte domain boundaries of the undoped and doped BaSnO3 for the first time, revealing that pure BaSnO3 exhibits mixed ionic-electronic conduction behavior under both oxidizing and reducing conditions, while the Sc-doping results in the gradual improvement of ionic (including protonic) conductivity, extending the electrolyte domain boundaries towards reduced atmospheres. This latter property makes the heavily-doped BaSnO3 representatives attractive for PCFC applications.

All-solid-state lithium-sulfur batteries (ASSB-LiS batteries) are considered among advanced candidates for next-generation energy storage systems, as they break with restrictions and limitations that liquid electrolytes impose on lithium-ion batteries and lithium-sulfur batteries (LiS-batteries), meaning enhanced safety and higher energy densities. However, investigations under realistic conditions on pouch cell level are challenging, as it is necessary to implement a scalable preparation method for sheet-type cathodes with high sulfur utilization and loading. In this study, a solvent-free process to prepare free-standing cathode sheets with low binder content down to 0.1 wt% PTFE is demonstrated. The contribution of binder and electrolyte on the conversion reaction of sulfur is discussed. Sheet-type cathodes reach nearly theoretical sulfur utilization of 1672 mAh gS-1 and outstanding reversible capacity reten-tion with 72% of initial discharge capacity after 400 cycles by adapting cut-off voltages to the stability window of the electrolyte. Furthermore, an all-solid-state pouch cell is demonstrated using the dry-film cathode, which is suc-cessfully tested for 50 cycles at different C-rates. Thickness monitoring of the cell stack gives fundamental insights into the volume change and breathing behavior of both cathode and anode.

The development of solid electrolytes has made significant progress in the last decade. Among the most promising materials, sulfide-based electrolytes show high ionic conductivities and low densities, and their precursors are abundant. For industrially relevant battery cells, sulfide electrolytes need to be processed to form thin electrolyte sheets that are either directly applied to the electrodes as coatings or prepared as stand-alone films. Thus, processing of sulfide electrolyte powders has recently drawn much attention as it seems to be one of the major challenges in realizing sulfide-based all-solid-state batteries. In this work, six different binders (NBR, HNBR, PIB, PBMA, SBS, SEBS) were selected for preparation of electrolyte films using Li6PS5Cl as a sulfidic model compound. The influence of the binders on the electrochemical performance as well as on the mechanical properties of the resulting films was investigated. In addition, binder blends were explored as a vial approach to optimize the properties of the electrolyte films. Special focus was put on elucidating the relation between the physico-chemical properties of the binder materials and the resulting electrochemical and mechanical properties of the electrolyte films.

In this work, the advanced all solid-state block copolymer electrolytes (SBCPEs) for lithium-ion batteries with double conductive phases, poly(ethylene oxide)-b-poly(trimethyl-N-((2-(dimethylamino)ethyl methacrylate)-7-propyl)-ammonium bis(trifluoromethanesulfonyl) imide) (PEO-b-PDM-dTFSI)/LiTFSI, were fabricated, in which the charged PDM-dTFSI block contained double quaternary ammonium cations and the PEO block was doped with LiTFSI. The disordered (DIS) and ordered lamellae (LAM) phase structures were achieved by adjusting the composition of the block copolymer and the doping ratio r. In addition, the presence of the hard PDM-dTFSI block and the formation of the LAM phase structure resulted in a good mechanical strength of the solid PEO-b-PDM-dTFSI/LiTFSI electrolyte, and it could maintain a high level of 104 Pa at 100 °C, which was around 10,000 times stronger than that of the PEO/LiTFSI electrolyte. Based on the good mechanical and electrochemical properties, the PEO-b-PDM-dTFSI/LiTFSI SBCPE exhibited excellent long-term galvanostatic cycle performance, indicating the strong ability to suppress lithium dendrites.

Solid-state inorganic magnesium batteries are considered as potential high energy storage devices of the future. Here we present a series of magnesium borohydride tetrahydrofuran (THF) composites, Mg(BH 4) 2 ⋅ xTHF(−MgO), 0≤x≤3, as solid-state electrolytes for magnesium batteries. Three new monoclinic compounds were identified, Mg(BH 4) 2 ⋅ 2/3THF (Cc), α-Mg(BH 4) 2 ⋅ 2THF (P2 1/c) and β-Mg(BH 4) 2 ⋅ 2THF (C2), and the detailed structures of α- and β-Mg(BH 4) 2 ⋅ 2THF are presented. The magnesium ionic conductivity of composites formed by these compounds were several orders of magnitude higher than that of the distinct compounds, x=0, 2/3, 2, and 3. The nanocomposite stabilized by MgO nanoparticles (∼50 nm), Mg(BH 4) 2 ⋅ 1.5THF−MgO(75 wt%), displayed the highest Mg 2+ conductivity, σ(Mg 2+)∼10 −4 S cm −1 at 70 °C, a high ionic transport number of t ion=0.99, and cyclic voltammetry revealed an oxidative stability of ∼1.2 V vs. Mg/Mg 2+. The electrolyte was stable towards magnesium electrodes, which allowed for stable Mg plating/stripping for at least 100 cycles at 55 °C with a current density of 0.1 mA cm −2. Finally, a proof-of-concept rechargeable solid-state magnesium battery was assembled with a magnesium metal anode and a TiS 2 cathode. A maximum discharge capacity of 94.2 mAh g −1 was displayed, which corresponds to y=0.2 in Mg yTiS 2.

Structural batteries aim to advance to 'massless' energy storage units. Here we report an electrode-less coaxial battery with a cork-internal shell, CFRP(+)/cork/Cu/Na2.99Ba0.005ClO/Al(-), where CFRP is carbon fiber reinforced polymer. The cell may, alternatively, solely have a cork external shell cork/Cu(+)/Na2.99Ba0.005ClO/Al(-). Cork is a cellular material with a negative CO2 footprint, light, elastic, impermeable to gases or liquids, and an excellent thermal insulator. Cork was used tandemly with a CFRP shell, working as the positive current collector to enhance the structural batteries' properties while allowing a giant electrostatic performance in conjunction with the Na+ solid-state ferroelectric injected between the Al negative collector and the cork. Cork was shown a polar dielectric. This 'minimalist' cell may perform without copper making the cells even more sustainable. Neither cells contain traditional electrodes, only one or two current collectors. The cells perform from 0 to >50 °C. The maximum capacity of the cork/Cu(+)/Na2.99Ba0.005ClO/Al(-) cells is ∼110 mAh.cm-2 (outer shell) with ≈ 90 μA cm-2, ≈ 0.90 V, Vmax ≈ 1.1-1.3 V, Imax ≈ 108 μA cm-2, and a constant resistance discharging life (>40 days). The novel family of cells presented may also harvest waste heat and thermal energy at a constant temperature as their potential and current increase with temperature. Conversely, rising potentials boost the cells' temperature, as expected from pyroelectrics, as shown herein. published

The electrochemical interactions between aluminum alloy 7075 and low-carbon steels under gelled electrolytes were studied. Such electrolytes provided the opportunity to investigate both thick and thin electrolyte systems. The electrolyte was chemically modified to visually track the acidic fronts during the anodic reaction and the subsequent hydrolysis process. Two mathematical models were validated for both thick and ultrathin electrolytes. The acidification of thick electrolytes was extended some millimeters beyond the aluminum alloy surface, whereas the acidic front was localized next to the metallic joint using ultrathin electrolytes. The combination of both numerical and experimental results allows proving (and explaining why) that the acidification process is more aggressive under dilute than under concentrated electrolytes., Dirección General de Asuntos del Personal Académico, Universidad Nacional Autónoma de México, Grant/Award Number: UNAM-DGAPA-PAPIIT-TA101521; Consejo Nacional de Ciencia y Tecnología,Grant/Award Numbers: 849228, 926694

Lithium-O2 batteries represent one of the most appealing candidates for battery electric vehicles (BEV) due to its remarkable theoretical high energy density, similar to fossil fuels. Solid polymer electrolytes represent a plausible solution to tackle some of the challenges associated to conventional liquid-based Li-O2 batteries, including safety concerns. Herein, cross-linked robust gel polymer electrolytes (GPE) based on poly(ethylene glycol) dimethacrylate (PEGDM) and tetraethylene glycol dimethyl ether (TEGDME) as plasticizer are prepared by rapid UV-photopolymerization. Both types of robust GPEs presented high ionic conductivity at room temperature (1.6·10−4 S·cm−1 and 1.4·10−3 S·cm−1 for single ion or dual ion, respectively). Both types of GPEs, single ion and dual ion lithium conductors, have been compared for the first time on Li-O2 cells. First, their performance was investigated in symmetrical Li|Li cells. In this case, the dual-ion GPE showed an outstanding behavior where the overpotential was

Lithium phosphorus oxynitride (LiPON) is an amorphous solid-state lithium ion conductor displaying exemplary cyclability against lithium metal anodes. There is no definitive explanation for this stability due to the limited understanding of the structure of LiPON. We provide a structural model of RF-sputtered LiPON via experimental and computational spectroscopic methods. Information about the short-range structure results from 1D and 2D solid-state nuclear magnetic resonance experiments investigating chemical shift anisotropy and dipolar interactions. These results are compared with first principles chemical shielding calculations of Li-P-O/N crystals and ab initio molecular dynamics-generated amorphous LiPON models to unequivocally identify the glassy structure as primarily isolated phosphate monomers with N incorporated in both apical and as bridging sites in phosphate dimers. Structural results suggest LiPON's stability is a result of its glassy character. Free-standing LiPON films are produced that exhibit a high degree of flexibility highlighting the unique mechanical properties of glassy materials.

Solid-state ion conductors are gaining increasing importance, among other ion conductors, to enable a transition to next-generation all-solid-state Li batteries. However, few lightweight and low-cost materials show sufficiently high Li-ion conduction at room temperature to be used as solid electrolytes. Here, we report the effect of adding nanosized oxides, SiO2, CaO, MgO, Î-Al2O3, TiO2, and ZrO2, to LiBH4 by ball-milling. In all cases, the room temperature Li-ion conductivity was greatly enhanced. For SiO2, which has been reported before as a conductivity enhancing material, the highest conductivity (4.1 × 10-5 S/cm at 40 °C) and the lowest activation energy (0.49 eV) were found at 20 v/v% SiO2. For the first time, ZrO2 and MgO were also added to LiBH4, leading to more than a 4 orders of magnitude increase in conductivity at 40 °C, reaching 0.26 and 0.18 mS/cm, respectively. Based on insights into the effect of structural properties on conductivity, we present a set of general guidelines to maximize the Li-ion conductivity in these nanocomposite solid electrolytes, independently of the type of oxide added. We expect that these results and insights will be helpful for the further development of new room temperature solid-state ion conductors.

Solid electrolytes with high Mg-ion conductivity are required to develop solid-state Mg-ion batteries. The migration energies of the Mg2+ ions of 5,576 Mg compounds tabulated from the inorganic crystal structure database (ICSD) were evaluated via high-throughput calculations. Among the computational results, we focused on the Mg2+ ion diffusion in Mg0.6Al1.2 Si1.8O6, as this material showed a relatively low migration energy for Mg2+ and was composed solely of ubiquitous elements. Furthermore, first-principles molecular dynamics calculations confirmed a single-phase Mg2+ ion conductor. The bulk material with a single Mg0.6Al1.2Si1.8O6 phase was successfully prepared using the sol-gel method. The relative density of the sample was 81%. AC impedance measurements indicated an electrical conductivity of 1.6 × 10−6 Scm−1 at 500°C. The activation energy was 1.32 eV, which is comparable to that of monoclinic-type Mg0.5Zr2(PO4)3.

Solid electrolyte materials are crucial for the development of high‐energy‐density all‐solid‐state batteries (ASSB) using a nonflammable electrolyte. In order to retain a low lithium‐ion transfer resistance, fast lithium ion conducting solid electrolytes are required. We report on the novel superionic conductor Li9AlP4 which is easily synthesised from the elements via ball‐milling and subsequent annealing at moderate temperatures and which is characterized by single‐crystal and powder X‐ray diffraction. This representative of the novel compound class of lithium phosphidoaluminates has, as an undoped material, a remarkable fast ionic conductivity of 3 mS cm−1 and a low activation energy of 29 kJ mol−1 as determined by impedance spectroscopy. Temperature‐dependent 7Li NMR spectroscopy supports the fast lithium motion. In addition, Li9AlP4 combines a very high lithium content with a very low theoretical density of 1.703 g cm−3. The distribution of the Li atoms over the diverse crystallographic positions between the [AlP4]9− tetrahedra is analyzed by means of DFT calculations., Lightweight and with fast lithium ion conduction: Solid electrolytes with a fast ion conduction are crucial for all‐solid‐state batteries. The new material Li9AlP4 combines a high lithium content and a high ionic mobility of 3 mS cm−1 at 25 °C with a very low theoretical density of 1.703 g cm−3.

Garnet-type structured electrolytes are considered a key technology for the next generation of lithium-ion batteries such as all-solid-state batteries. Cubic Garnet-type solid oxides with composition Li5+xLa3(Nb2−xZrx)O12 (x between 0 and 1.5) were synthesized by solid-state reaction and sintered by spark plasma sintering. Powder characterization indicates the formation of solid solution with high chemical homogeneity and spherical particles. High relative densities (>96%) were obtained by spark plasma sintering at 950 °C for 10 min and pressure application of 50 MPa. Although the formation of secondary phase La2Zr2O7 was identified by the X-ray diffraction patterns of Zr-doped pellets, it has been eliminated for x = 0.75 and 1 by conventional heat treatment at 850 °C for 1 h. High ionic conductivity values were attained for x ≥ 0.75, reaching a maximum value in the order of 10−4 S.cm−1 at 25 °C with activation energy of 0.38 eV. The results indicated that Zr4+ promoted significant increasing of the lithium-ion conductivity by lowering the activation energy.

The ability of some solid materials to exhibit exceptionally high ionic conductivities has been known since the observations of Michael Faraday in the nineteenth century (Faraday M. 1838Phil. Trans. R. Soc.90), yet a detailed understanding of the atomic-scale physics that gives rise to this behaviour remains an open scientific question. This theme issue collects articles from researchers working on this question of understanding fast-ion conduction in solid electrolytes. The issue opens with two perspectives, both of which discuss concepts that have been proposed as schema for understanding fast-ion conduction. The first perspective presents an overview of a series of experimental NMR studies, and uses this to frame discussion of the roles of ion–ion interactions, crystallographic disorder, low-dimensionality of crystal structures, and fast interfacial diffusion in nanocomposite materials. The second perspective reviews computational studies of halides, oxides, sulfides and hydroborates, focussing on the concept offrustrationand how this can manifest in different forms in various fast-ion conductors. The issue also includes five primary research articles, each of which presents a detailed analysis of the factors that affect microscopic ion-diffusion in specific fast-ion conducting solid electrolytes, including oxide-ion conductorsGd2Zr2O7andBi4V2O11, lithium-ion conductorsLi6PS5BrandLi3OCl, and the prototypical fluoride-ion conductorβ-PbF2.This article is part of the Theo Murphy meeting issue ‘Understanding fast-ion conduction in solid electrolytes’.

Fast Li+ solid ion conductors are a key component of all-solid-state batteries, a technology currently under development. The possible use of metallic lithium as active material in solid-state batteries warrants a quantum step improvement of battery specific energy, enabling further electric vehicles application. Hereby, we report the synthesis and ion conduction properties of a new solid hybrid electrolyte based on the MIL-121 metal organic framework (MOF) structure. After an ion exchange procedure that introduces Li+ in the structure, a known quantity of a soaking electrolyte is incorporated. The soaking electrolyte is based on the EMIM-TFSI ionic liquid, thus we can classify our formulation as a MOF–ionic liquid hybrid solid electrolyte. Electrical conductivity is investigated by impedance spectroscopy and preliminary studies of ion dynamics are conducted by 7Li NMR. The field of MOF-based ion conductors remains in incipient stages of research. Our report paves the way towards the rational design of new solid-state ion conductors.

The key component in lithium solid-state batteries (SSBs) is the solid electrolyte composed of lithium superionic conductors (SICs). Lithium oxide SICs offer improved electrochemical and chemical stability compared with sulfides, and their recent advancements have largely been achieved using materials in the garnet- and NASICON (sodium superionic conductor)- structured families. In this work, using the ion-conduction mechanisms in garnet and NASICON as inspiration, a common pattern of an “activated diffusion network” and three structural features that are beneficial for superionic conduction: a 3D percolation Li diffusion network, short distances between occupied Li sites, and the “homogeneity” of the transport path are identified. A high-throughput computational screening is performed to search for new lithium oxide SICs that share these features. From this search, seven candidates are proposed exhibiting high room-temperature ionic conductivity evaluated using ab initio molecular dynamics simulations. Their structural frameworks including spinel, oxy-argyrodite, sodalite, and LiM(SeO3)2 present new opportunities for enriching the structural families of lithium oxide SICs.

Gas separation in dense ceramic membranes is driven by the partial pressure gradient across the membrane. The mixed conducting materials most commonly used are single-phase perovskites or fluorites. In recent years, the development of dual-phase systems combining a mixed ion-conducting and electron-conducting phase has increased. The advantage is that a larger number of very stable materials systems is available. The membrane designs currently used include planar, tubular, hollow-fiber, and honeycomb membranes. Each of these designs has specific advantages and disadvantages, depending on the application. Innovative joining concepts are also often needed due to the high temperatures involved. These usually involve the use of glass-ceramic sealants or reactive metal brazes. Applications focus either on the separation of gases alone, i.e., the supply of oxygen or hydrogen, or on membrane reactors. In membrane reactors, a chemical reaction occurs on one or both sides of the membrane in addition to gas separation. The supply of gases is of potential interest for power plants, for the cement, steel, and glass industries, for the medical sector, and for mobile applications. Membrane reactors can be used to produce base chemicals or synthetic fuels.

Li7La3Zr2O12 (LLZO) is a promising and safe solid electrolyte for all-solid-state batteries. To achieve high ionic conductivity of LLZO, stabilizing the cubic phase and reducing Li loss during the sintering process is essential. Therefore, reducing the sintering temperature, which increases the sintering time for high-density pellets, is necessary. Herein, we investigate the change in the crystal structure, morphology, and Li ionic conductivity of LLZO pellets by triple doping with Al, Ga, and Ta and modulating the variation in initial Li concentrations. Interestingly, the proportion of the conductive cubic phase increased with increasing Li stoichiometry by 1.1 times, and this tendency was further accelerated by triple doping. The synergetic effects of triple doping and Li concentration also minimized Li loss during sintering. Accordingly, it provided a high-quality LLZO pellet with good ionic conductivity (3.6 × 10−4 S cm−1) and high relative density (97.8%). Notably, the LLZO pellet was obtained using a very short sintering process (40 min). Considering that the most time-consuming step is the sintering process for LLZO, this study can provide guidelines for the fast production and commercialization of LLZO electrolytes with high ionic conductivity.

The all‐solid‐state battery (ASSB) is a promising candidate for electrochemical energy storage. In view of the limited availability of lithium, however, alternative systems based on earth‐abundant and inexpensive elements are urgently sought. Besides well‐studied sodium compounds, potassium‐based systems offer the advantage of low cost and a large electrochemical window, but are hardly explored. Here we report the synthesis and crystal structure of K‐ion conducting T5 KSi2P3 inspired by recent discoveries of fast ion conductors in alkaline phosphidosilicates. KSi2P3 is composed of SiP4 tetrahedra forming interpenetrating networks of large T5 supertetrahedra. The compound passes through a reconstructive phase transition from the known T3 to the new tetragonal T5 polymorph at 1020 °C with enantiotropic displacive phase transitions upon cooling at about 155 °C and 80 °C. The potassium ions are located in large channels between the T5 supertetrahedral networks and show facile movement through the structure. The bulk ionic conductivity is up to 2.6×10−4 S cm−1 at 25 °C with an average activation energy of 0.20 eV. This is remarkably high for a potassium ion conductor at room temperature, and marks KSi2P3 as the first non‐oxide solid potassium ion conductor., Size matters: Only a structure with large T5 supertetrahedra enables fast K+‐ion conduction in the polymorphic phosphidosilicate KSi2P3.

Nos últimos anos, as células a combustível de membrana de troca protônica em alta temperatura (HT-PEMFC) foram objetos de diversas pesquisas a fim de remover muitos desafios levantados durante a operação em baixa temperatura. O estado-da-arte em eletrólitos para PEMFC, Nafion®, apresenta mecanismos de condução de prótons altamente dependentes de água, o que limita a operação nesses sistemas em 100ºC. O aumento da temperatura de operação de uma célula PEMFC é desejado devido à contribuição da temperatura na aceleração das reações eletroquímicas. Contudo, o aumento da temperatura exige uma nova proposta para eletrólitos, seja por otimização das propriedades do Nafion ou por desenvolvimento de membranas que não dependam de água para a condução protônica. Neste contexto, as membranas de PBI (polibenzimidazol) dopadas com ácido fosfórico têm sido consideradas uma alternativa bastante promissora para eletrólitos sólidos operantes em alta temperatura, devido à combinação de condução de prótons satisfatória em condições de baixa umidade relativa e excelente estabilidade térmica. No entanto, membranas baseadas em PBI apresentam algumas desvantagens como perda do ácido que pode ocorrer por meio de uma série de mecanismos, incluindo evaporação, difusão, transporte capilar ou lixiviação por água condensada. Mesmo assim, a tecnologia HT-PEMFC é mais interessante, pois, ela trabalha acima da temperatura de ebulição da água, portanto a água gerada está representada apenas na fase de vapor, dessa forma, modelos monofásicos são mais simples de estudar computacionalmente. Dessa forma, foram estudados dois modelos de formato de placas: serpentina com múltiplos canais e interdigital, com área geométrica de eletrodo de 5 cm2 através de simulações computacionais no software COMSOL Multiphysics 5.3a, sendo desenvolvidos e validados com a intenção de auxiliar na interpretação de resultados experimentais. Com isso, o presente trabalho priorizou estudos experimentais e computacionais quanto ao comportamento do ácido fosfórico na membrana, difusão reversa de vapor d\'água e distribuição de temperatura através da membrana, fluxo dos gases, carga de catalizadores, alteração do substrato, tipos de combustíveis e mudanças no posicionamento de entrada e saída dos canais de fluxo dos gases. Em geral as curvas de polarização apresentadas, mostraram uma boa concordância entre os resultados experimentais e computacionais. Foi demonstrado que uma quantidade considerável de vapor d\'água pode atravessar o MEA no sentido do cátodo para o ânodo. Em geral, o aumento da estequiometria favoreceu o aumento do desempenho da célula e foi constatado que a fração molar de ácido fosfórico diminui com o aumento da temperatura e da umidade relativa. In recent years, high temperature proton exchange membrane fuel cells (HT-PEMFC) have been the subject of several researches in order to remove many challenges raised during low temperature operation. The state-of-the-art electrolyte for PEMFC, Nafion®, features highly water-dependent proton conduction mechanisms, which limits operation in these systems to 100ºC. The increase in operating temperature of a PEMFC cell is desired due to the contribution of temperature to the acceleration of electrochemical reactions. However, the increase in temperature requires a new proposal for electrolytes, either by optimizing the properties of Nafion or by developing membranes that do not depend on water for proton conduction. In this context, phosphoric acid-doped PBI (polybenzimidazole) membranes have been considered a very promising alternative for solid electrolytes operating at high temperature, due to the combination of satisfactory proton conduction under conditions of low relative humidity and excellent thermal stability. However, PBI-based membranes have some disadvantages such as acid loss that can occur through a series of mechanisms, including evaporation, diffusion, capillary transport or leaching by condensed water. Even so, the HT-PEMFC technology is more interesting because it works above the boiling temperature of water, so the water generated is represented only in the vapour phase, thus, single-phase models are simpler to study computationally. Thus, two plate format models were studied: serpentine with multiple channels and interdigital, with a geometric electrode area of 5 cm2 through computer simulations in COMSOL Multiphysics 5.3a software, being developed and validated with the intention of helping in the interpretation of experimental results. Thus, the present work prioritized experimental and computational studies on the behavior of phosphoric acid in the membrane, back diffusion of water vapor and temperature distribution in the membrane, gas flow, catalyst charge, change substrate, fuel types, and changes in inlet and outlet placement of gas flow channels. In general, the presented polarization curves showed a good agreement between the experimental and computational results. It has been shown that a considerable amount of water vapour can cross through the MEA from the cathode to the anode. In general, the increase in stoichiometry favored the increase in cell performance and it was found that the molar fraction of phosphoric acid decreases with increasing temperature and relative humidity.

Batteries gained a lot of attention due to a raising demand for energy storage, as required for renewable energy generation systems, portable electronics and transport applications. For the development of new battery materials understanding of fundamental processes is essential, which often relies on the development of new characterisation techniques and tools that enable to study the underlying electrochemical processes at the relevant length scales, i.e. from an atomistic to a macroscopic level. Future batteries should be able to store more energy (per unit mass and or volume) and should be safer. Battery material solutions to achieve this are in principle known, where this thesis focusses on: (1) Si being one of the most promising negative electrode based on its large Li storage capacity (ten times higher than current graphite) and (2) solid electrolytes, replacing liquid electrolytes, which would practically annihilate safety concerns of Li batteries. However, for these new battery materials the challenge is to achieve a long cycle life by slowing down, or even preventing degradation reactions at the interfaces between the electrode and the electrolyte. This is the binding theme, and the topic of the main research questions of this thesis are thus: What are these degradation mechanisms and what is the impact of strategies to prevent it and achieve a long cycle life. The focus in this thesis is on Si negative electrodes in combination with liquid electrolytes in general, and for solid electrolytes in particular

Nuclear magnetic resonance offers a wide range of tools to analyse ionic jump processes in crystalline and amorphous solids. Both high-resolution and time-domain 1 , 2 H , 6 , 7 Li , 19 F , 23 Na NMR helps throw light on the origins of rapid self-diffusion in materials being relevant for energy storage. It is well accepted that Li + ions are subjected to extremely slow exchange processes in compounds with strong site preferences. The loss of this site preference may lead to rapid cation diffusion, as is also well known for glassy materials. Further examples that benefit from this effect include, e.g. cation-mixed, high-entropy fluorides ( Ba, Ca) F 2 , Li-bearing garnets ( Li 7 La 3 Zr 2 O 12 ) and thiophosphates such as LiTi 2 ( PS 4 ) 3 . In non-equilibrium phases site disorder, polyhedra distortions, strain and the various types of defects will affect both the activation energy and the corresponding attempt frequencies. Whereas in ( Me, Ca ) F 2 ( Me = Ba , Pb ) cation mixing influences F anion dynamics, in Li 6 PS 5 X ( X = Br , Cl , I ) the potential landscape can be manipulated by anion site disorder. On the other hand, in the mixed conductor Li 4 + x Ti 5 O 12 cation-cation repulsions immediately lead to a boost in Li + diffusivity at the early stages of chemical lithiation. Finally, rapid diffusion is also expected for materials that are able to guide the ions along (macroscopic) pathways with confined (or low-dimensional) dimensions, as is the case in layer-structured RbSn 2 F 5 or MeSnF 4 . Diffusion on fractal systems complements this type of diffusion. This article is part of the Theo Murphy meeting issue ‘Understanding fast-ion conduction in solid electrolytes’.

Complex metal hydrides have recently gained interest as solid electrolytes for all-solid-state batteries due to their light weight, easy deformability, and fast ion mobility at elevated temperatures. However, increasing their low conductivity at room temperature is a prerequisite for application. In this review, two strategies to enhance room temperature conductivity in complex metal hydrides, nanostructuring and nanocomposite formation, are highlighted. First, the recent achievements in nanostructured complex metal hydride-based ion conductors and complex metal hydride/metal oxide nanocomposite ion conductors are summarized, and the trends and challenges in their preparation are discussed. Then, the reported all-solid-state batteries based on complex metal hydride nanocomposite electrolytes are highlighted. Finally, future research directions and perspectives are proposed, both for the preparation of improved metal hydride ion conductors, as well as metal hydride-based all-solid-state batteries.

The high-resistive grain boundaries are the bottleneck for Li+ transport in Li7La3Zr2O12 (LLZO) solid electrolytes. Herein, high-conductive LLZO thin films with cubic phase and amorphous domains between crystalline grains are prepared, via annealing the repetitive LLZO/Li2CO3/Ga2O3 multi-nanolayers at 600 °C for 2 h. The amorphous domains may provide additional vacant sites for Li+, and thus relax the accumulation of Li+ at grain boundaries. The significantly improved ionic conductivity across grain boundaries demonstrates that the high energy barrier for Li+ migration caused by space charge layer is effectively reduced. Benefiting from the Li+ transport paths with low energy barriers, the presented LLZO thin film exhibits a cutting-edge value of ionic conductivity as high as 6.36 × 10−4 S/cm, which is promising for applications in thin film lithium batteries.

The high-resistive grain boundaries are the bottleneck for Li+ transport in Li7La3Zr2O12 (LLZO) solid electrolytes. Herein, high-conductive LLZO thin films with cubic phase and amorphous domains between crystalline grains are prepared, via annealing the repetitive LLZO/Li2CO3/Ga2O3 multi-nanolayers at 600 °C for 2 h. The amorphous domains may provide additional vacant sites for Li+, and thus relax the accumulation of Li+ at grain boundaries. The significantly improved ionic conductivity across grain boundaries demonstrates that the high energy barrier for Li+ migration caused by space charge layer is effectively reduced. Benefiting from the Li+ transport paths with low energy barriers, the presented LLZO thin film exhibits a cutting-edge value of ionic conductivity as high as 6.36 × 10−4 S/cm, which is promising for applications in thin film lithium batteries.

Assembling all-solid-state batteries presents a unique challenge due to chemical and electrochemical complexities of interfaces between a solid electrolyte and electrodes. While the interface stability is dictated by thermodynamics, making use of passivation materials often delays interfacial degradation and extends the cycle life of all-solid cells. In this work, we investigated antiperovskite lithium oxychloride, Li3OCl, as a promising passivation material that can engineer the properties of solid electrolyte-Li metal interfaces. Our experiment to obtain stoichiometric Li3OCl focuses on how the starting ratios of lithium and chlorine and mechanochemical activation affect the phase stability. For substantial LiCl excess conditions, the antiperovskite phase was found to form by simple melt-quenching and subsequent high-energy ball-milling. Li3OCl prepared with 100% excess LiCl exhibits ionic conductivity of 3.2 × 10-5 S cm-1 at room temperature, as well as cathodic stability against Li metal upon the extended number of cycling. With a conductivity comparable to other passivation layers, and stable interface properties, our Li3OCl/LiCl composite has the potential to stably passivate the solid-solid interfaces in all-solid-state batteries.

A study of the Solid Electrolyte Interphase (SEI) on hard-carbon (HC) electrodes in sodium half-cells is presented. Electrochemical performances over > 100 cycles were compared with two different salts (NaPF6, NaTFSI) and two different electrolyte additives (FEC, DMCF) in a mixture of EC and DMC solvents. The best electrochemical performances were observed with NaPF6 salt in conjunction with 3% FEC. The DMCF additive had a detrimental effect in all electrolyte combinations. The chemical characterization of the SEI was carried out by X-ray Photoelectron Spectroscopy (XPS) and showed that the best electrochemical behavior was related to an SEI composition based on sodium ethylene dicarbonate and NaF, whereas poorer electrochemical performances were associated to either low NaF or high Na2CO3 content. The results reported herein provide an insight on the SEI chemistry on hard carbon electrodes in sodium cells after long-term cycling, as a complement to previous studies dealing with the first cycles., Authors acknowledge the European Commission for funding through H2020 NAIADES project (LCE10–2014, grant nb. 646433). EI, MRP and AP acknowledge Ministerio de Economía y Competititivad (Spain) for Severo Ochoa Programme for Centres of Excellence in R&D (SEV-2015-0496). This work has been done in the frame of the Doctoral Degree Program in Chemistry by the Universitat Autònoma de Barcelona. JF, CC and RD acknowledge Agence Nationale de la Recherche (ANR) for its “Investment for the Future” Program through I-SITE E2S-UPPA funding.

In this study, Si nanoparticles with interweaving carbon nanotubes are wrapped by graphitic sheets to achieve high conductivity and high dimensional stability of a composite anode (denoted as Si/CNT/G) for Li-ion batteries. In addition, an ionic liquid (IL) electrolyte that consists of ether-side-chain pyrrolidinium, asymmetric imide, and a high Li+ fraction is prepared. This electrolyte is for the first time employed for Si-based Li-ion batteries. Decomposition of the ether groups creates organic components in the solid electrolyte interphase (SEI). The high Li+ concentration promotes decomposition of the (fluorosulfonyl)(trifluoromethanesulfonyl)imide (FTFSI−) anions, leading to a LiF- and Li3N-rich SEI. The organic-inorganic balanced SEI is responsible for the excellent charge-discharge properties of the Si/CNT/G anode. The FTFSI− anions exhibit low corrosivity toward the Al current collector and high compatibility with the LiNi0.8Co0.1Mn0.1O2 (NCM-811) cathode. With a charging voltage of 4.5 V, remarkable reversible capacities and cycling stability of NCM-811 in the high-Li+-fraction N-methoxyethyl-N-methylpyrrolidinium/FTFSI IL electrolyte are observed. Differential scanning calorimetry is used to examine the interfacial exothermic reactions between the delithiated NCM-811 and various electrolytes. After 300 charge-discharge cycles, the capacity retention of a Si/CNT/G||NCM-811 full cell with the proposed IL electrolyte is 80% with a Coulombic efficiency of ∼99.9%. These values are significantly higher than those of the conventional carbonate electrolyte cell.

Ni–Zr0.82Y0.18O1.91 (YSZ) and Ni–La0.90Sr0.10ScO2.95 (LSS) cermets for solid oxide and protonic ceramic electrochemical cells were studied by means of H/D isotope exchange with the gas phase equilibration method for the first time. The experiments were carried out at 2 mbar of dry hydrogen in the temperature range of 400–800 ᵒC. The three parallel channels of hydrogen surface exchange were found to exist in both Ni-YSZ and Ni-LSS cermets. The mechanism of hydrogen isotope exchange for Ni-YSZ was found to be temperature independent, while, in the case of Ni-LSS, the mechanism changed with temperature and was more complicated at lower temperatures (400–600 °C). It was revealed that hydrogen spillover was the rate-determining step for both cermets. The electrochemical kinetics of hydrogen oxidation were studied on symmetric cells with a YSZ supported electrolyte and Ni-YSZ electrodes and with an LSS supported electrolyte and Ni-LSS electrodes in a wet (3 vol % H 2O) hydrogen atmosphere at 1 atm. The mechanism of hydrogen oxidation on the Ni-LSS electrode differs from that of the Ni-YSZ electrode. It changes with temperature and is also more complicated at a lower temperature range. © 2021 Elsevier B.V. This work is supported by the State Assignment of Ministry of Science and Higher Education of the Russian Federation [No. AAAA-A19-119020190078-6 ], and the Act 211 of the Government of the Russian Federation, agreement [No. 02. A03.21.0006 ]. The facilities of the Shared Access Centre “Composition of Compounds” and Unique Scientific Setup “Isotopic Exchange” of IHTE UB RAS were used. The authors are grateful D.M. Solodyankina and A.Yu. Stroeva for support in the preparation of samples.

Alkali borophosphate glasses have recently gained strong interest, not only for their fundamental importance due to the mixed glass former effect but also because of their potential applicability as solid state electrolytes in energy harvesting devices. In the present work, internal friction measurements of lithium and sodium borophosphate glasses have been performed in order to look for further insights on the relationships between the ionic conduction mechanism and the structure of the glasses that has been previously determined. Absorption of acoustic waves shows two marked internal friction peaks with activation energy in the range of the activation energy for the ionic conduction of the glasses between 0.5 and 0.7 eV. Furthermore, the substitution of phosphorus by boron network former results in the decrease of the activation energy associated to both processes in parallel to the E of the ionic conduction of alkali cations; and the relationship between the areas of both peaks suggests a change of the distribution of alkali ions between positions energetically different in agreement with the structural changes of the glass network., The authors would like to thank F. Černobila for technical assistance. This study was supported by project VEGA No. 1/0510/17 and ITMS: 26220120046 co-funded from EU sources and European Regional Development Fund. F.M. thanks also funding from project MAT2017-87035-C2-1-P (AEI/FEDER, UE).

International audience; Partially biobased poly(1,2,3-triazolium)s are synthesized by reversible additionfragmentation chain transfer (RAFT) polymerization of tailor-made 1,2,3-triazole-functionalized (meth)acrylate monomers derived from levulinic acid, followed by N-alkylation of the 1,2,3-triazole moieties by methyl iodide (CH3I) and subsequent anion exchange with lithium bis(trifluoromethylsulfonyl)imide (LiTFSI). Chain extension of a 1,2,3-triazole-functionalized polymethacrylate by RAFT polymerization of styrene followed by N-alkylation with CH3I and anion exchange with LiTFSI affords two poly(1,2,3-triazole)- and two poly(1,2,3-triazolium)-based diblock copolymers (BCPs) with different weight fractions of each block. Discussion of the structure/properties relationships of all obtained materials is based on NMR spectroscopy, size exclusion chromatography, differential scanning calorimetry, thermogravimetric analysis, and broadband dielectric spectroscopy. The morphological and self-assembling properties of neutral and charged BCPs in bulk and in thin films are investigated by small-angle X-ray scattering and atomic force microscopy experiments, respectively.

Eliminating the uncontrolled growth of Li dendrite inside solid electrolytes is a critical tactic for the performance improvement of all‐solid‐state Li batteries (ASSLBs). Herein, a strategy to swallow and anchor Li dendrites by filling Si nanoparticles into the solid electrolytes by the lithiation effect with Li dendrites is proposed. It is found that Si nanoparticles can lithiate with the adjacent Li dendrites which have a strong electron transport ability. Such effect can inhibit the formation of Li dendrites at the interface of Li anode, and also swallow the tip Li inside the solid electrolytes, and thus inhibiting its longitudinal growth and avoiding the solid electrolyte puncturing. As a proof of concept, a novel sandwich‐structure solid electrolyte of Li6.7La3Zr2Al0.1O12 (LLZA)‐PEO/Si‐PEO electrolyte/ (LLZA)‐PEO with asymmetrical structure is first constructed and demonstrated stable Li plating/stripping over 1800 h and remarkably improved cycling stability in Li/LiFePO4 cells with a reversible capacity of 111.9 mAh g−1 at 1 C after 150 cycles. The proof of lithiation of Si‐PEO electrolyte in the interlayer is also verified. Furthermore, the pouch cell thus prepared exhibits comparable cyclic stability and is allowable for folding and cutting, suggesting its promising application in ASSLBs by this simple and efficient strategy.

Li6-xZr2-xAxO7 (A = Nb, Ta) system with 0 &lt, x &lt, 0.30 is synthesized by glycine-nitrate method. Boundaries of solid solutions based on monoclinic Li6Zr2O7 are determined, temperature (200–600 °C) and concentration dependences of conductivity are investigated. It is shown that monoclinic Li6Zr2O7 exhibits better transport properties compared to its triclinic modification. Li5.8Zr1.8Nb(Ta)0.2O7 solid solutions have a higher lithium-cation conductivity at 300 °C compared to solid electrolytes based on other lithium zirconates due the “open” structure of monoclinic Li6Zr2O7 and a high solubility of the doping cations.

Mixed (Cu6PS5I)1–x(Cu7PS6)x crystals were grown using a direct crystallization technique. Being based on the X-ray diffraction data, their crystal structure was studied, showing face-centred cubic lattice for Cu6PS5I-rich solid solutions (х < 0.12) and primitive cubic lattice for Cu7PS6-rich (0.84 < x < 1) solid solutions. These structural data correlate with the Raman spectra where, besides the common features typical for the argyrodite-type Cu6PS5I and Cu7PS6 crystals, weaker bands characteristic only for the end-point compounds are revealed in the corresponding compositional intervals.

International audience; The search for Li ions conducting ceramics is burgeoning, owing to the regain interest for solid state batteries. Here we investigate the effect of Mg substitutions on the ionic conductivity of the A2SnO3 (A = Li, Na) phases. Pure A1.8Mg0.1SnO3 and A2.2Mg0.1Sn0.9O3 were structurally characterized and their ionic conductivity was measured by AC impedance spectroscopy. We show a decrease of the activation energy with increasing the Mg substitution and found ionic conductivities three and two orders of magnitude higher for Li2.2Mg0.1Sn0.9O3 and Na1.8Mg0.1SnO3 as compared to pristine Li2SnO3 and Na2SnO3, respectively. Neutron diffraction was used to determine the Mg localization in the crystal structure and to provide a rationale for the ionic conductivity changes. Our results confirm the high sensitivity of the ionic conductivity on chemical substitutions, even limited ones.

Lithium salt (noncoordinating anions, such as lithium triflate (Ltf)) gel electrolytes may be key for the practical use of electrochemical devices. We introduce a new lyotropic liquid-crystalline (LLC) mesophase using Ltf, a small amount of water (as low as 1.3 water per Ltf), and nonionic surfactant (C18H37(OCH2CH2)(10)OH, C18E10. The LLC phase forms over a broad range of Ltf/C18E10 mole ratios, 2-18. The clear ethanol solution of the ingredients can be either directly spin-coated over a glass substrate to form a gel phase or it can be prepared as a gel by mixing Ltf, water, and C18E10. The mesophase leaches out surfactant molecules at low salt concentrations, but at a salt/surfactant mole ratio of above 8, the phase is homogeneous with a cubic mesostructure, fully transparent in the visible optical region, mechanically flexible, and an effective gel electrolyte. We have observed a large electrostatic doping on graphene with the Fermi energy level of similar to 1.0 eV using Ltf-C18E10 gel electrolytes. The Ltf-based gels demonstrate better properties than commonly used ionic liquid electrolyte in graphene optical modulators. The stability of the new gel electrolytes and their superior performance make them suitable electrolytes for use in graphene-based optical modulators.

International audience; Pure tysonite La0.95Ba0.05F2.95 is nanostructured by using the ball-milling technique. Size and pollution rate are minimized using the statistical method of Design of Experiment. The nanocrystalline powders are studied by X-ray and TEM analyses and by 19F solid state NMR and impedance spectroscopies. Specific surface area and F/OH substitution rate are estimated by BET measurements and thermal analysis (TGA-MS), respectively. Fluorine environments and mobilities are discussed on the basis of 19F solid state NMR data, both prior and after thermal treatment. The ionic conductivity, evaluated from sintered pellets, is compared at different thermal treatment temperatures. Thermal treatment tends to reduce microstrains up to 500 °C and to increase the grain size above this temperature. Optimal conductivity is obtained for a thermal treatment from 700 °C and no significant improvement of the conductivity by nanostructuration is observed.

Solid electrolytes with high Mg-ion conductivity are required to develop solid-state Mg-ion batteries. The migration energies of the Mg2+ ions of 5,576 Mg compounds tabulated from the inorganic crystal structure database (ICSD) were evaluated via high-throughput calculations. Among the computational results, we focused on the Mg2+ ion diffusion in Mg0.6Al1.2 Si1.8O6, as this material showed a relatively low migration energy for Mg2+ and was composed solely of ubiquitous elements. Furthermore, first-principles molecular dynamics calculations confirmed a single-phase Mg2+ ion conductor. The bulk material with a single Mg0.6Al1.2Si1.8O6 phase was successfully prepared using the sol-gel method. The relative density of the sample was 81%. AC impedance measurements indicated an electrical conductivity of 1.6 × 10−6 Scm−1 at 500°C. The activation energy was 1.32 eV, which is comparable to that of monoclinic-type Mg0.5Zr2(PO4)3., GRAPHICAL ABSTRACT

Driven by all-solid-state battery (ASSB) applications there is an increased interest in understanding the dynamics of solid electrolytes (SEs) and ASSBs. Particularly, the large charge transfer resistances at the various ASSB interfaces are still subject to scientific discussions requiring further investigations. To advance ASSB design, fundamental knowledge of the underlying processes at both the heterogeneous SE-electrode-interfaces and the homogeneous SE-SE-interfaces, i.e., grain boundaries, are essential. In this contribution, we explore transport and interfacial processes in ASSB cells by a continuum modelling framework and numerical simulations. Special attention is paid to the coupled multi-physics at heterogeneous SE-electrode-interfaces and their feedback to bulk properties. Local balancing processes lead to charge accumulation at the solid-solid interface and the formation of charged zones, i.e., space charge layers (SCL), in the near interface regions. These local charge distributions cause locally strong electric fields, induce large changes in the mechanical field sizes, and lead to local changes in the energy states. The numerical investigation of these boundary layers on the nanometer scale in a continuum approach requires suitably refined models. Therefore, previous approaches either resolve the SCLs [1] or consider scales beyond the SCL width and use less intense bulk type models to examine the interaction of physical processes and numerically demanding microstructures in composite electrodes [2, 3]. We combine the advantages of both approaches yielding a multi-scale model, which is based upon a free energy model, extending earlier work [1] by including mechanical and configurational contributions of detailed lattice structural properties on the atomic scale. The resulting improved transport model is combined with a new active interface model including the electrode SCL. The interfaces are active in the sense that they carry dynamical responding interfacial species. This enables the description of charge transfer and intercalation as a multi-step process and to split the electrical current crossing the interfaces into charge transferred by a defect reaction mechanism and a polarization induced contribution. In the quasi-static regime, we deduce material dependent, non-linear, differential capacities characterizing the SCLs without spatial resolution. These capacities serve as theory-based input in 3D microstructure-resolved simulations and bridge the scales. This model is used to simulate charge/discharge, cyclic voltammetry and impedance measurements for ASSBs; it is validated with experimental data. Furthermore, we study and identify individual contributions of the interface processes as well as time scales. Particularly, we show that the phase-interface processes are affected by bulk properties such as grain boundaries. [1] S. Braun, C. Yada, A. Latz, J. Phys. Chem. C., 2015, 19, 22249. [2] A. Latz, J. Zausch, Beilstein Journal of Nanotechnology, 2015, 6, 987-1007. [3] M. Finsterbusch, T. Danner, C.-L. Tsai, S. Uhlenbruck, A. Latz and O. Guillion, ACS Applied Materials & Interfaces, 2018, 10, 22329.

Solid electrolytes for Li transport have been prepared by melt-compounding in one single step. Electrolytes are composed of polyvinylidene fluoride&ndash, hexafluoropropylene (PVDF&ndash, HFP) with PYR13TFSI on its own or with varying concentration of LiTFSI. While the extrusion of PVDF&ndash, HFP with PYR13TFSI is possible up to relatively high liquid fractions, the compatibility of PVDF&ndash, HFP with LiTFSI/PYR13TFSI solutions is much lower. An organo-modified sepiolite with D-&alpha, tocopherol polyethylene glycol 1000 succinate (TPGS-S) can be used to enhance the compatibility of these blends and allows to prepare homogeneous PYR13TFSI/LiTFSI/PVDF&ndash, HFP electrolytes with controlled microphase separations by melt-compounding. The structure and morphology of the electrolytes has been studied by FTIR, differential scanning calorimetry (DSC), SEM, and AFM. Their mechanical properties have been studied by classical strain&ndash, stress experiments. Finally, ionic conductivity has been studied in the &minus, 50 to 90 &deg, C temperature range and in diffusivity at 25 &deg, C by PFG-NMR. These electrolytes prove to have a microphase-separated morphology and ionic conductivity which depends mainly on their composition, and a mechanical behavior typical of common thermoplastic polymers, which makes them very easy to handle. Then, in this solvent-free and scalable fashion, it is possible to prepare electrolytes like those prepared by solvent casting, but in few minutes instead of several hours or days, without solvent evaporation steps, and with ionic conductivities, which are very similar for the same compositions, above 0.1 mS&middot, cm&minus, 1 at 25 &deg, C. In addition, some of the electrolytes have been prepared with high concentration of Li ion, what has allowed the anion exchange Li transport mechanism to contribute significantly to the overall Li diffusivity, making DLi become similar and even clearly greater than DTFSI.

Lithium-ion rechargeable batteries are currently the state-of-the-art energy storage technology for devices as cell phones, laptops and electric cars. Despite their top perfomances, some problems have yet to be solved. The first issue is availability: lithium is diffcult to recycle and, while still available in large quantities, not enough to support a future economy based on electric vehicles. The second problem is performances: despite Li-ion batteries are state-of-the-art among other battery technologies, their performances are still not performing as fossil fuels, in terms of energy density and power density. The last issue is safety: Li-ion batteries have been reported to heat up, catch fire or even explode. Most of such safety issues come from the electrolyte, which is the most flammable element in a battery. Typical electrolytes are also toxic, and can easily leak out of a battery. Among the possible alternatives to Li-ion batteries, sodium-ion batteries and magnesium-ion batteries are particularly relevant, since both sodium and magnesium are far more abundant in nature and hence less expensive than lithium. One of the biggest challenges in realizing sodium- or magnesium-ion batteries is represented by finding materials suitable to intercalate such ions with competitive performances with respect to lithium-ion ones, especially as far as the negative electrode is concerned; this is due to the fact that graphite, the most commonly used material for lithium-ion batteries, cannot intercalate sodium or magnesium to a signi cative extent. A promising substitute is C60 fullerene, which can host in its crystal structure Na ions and Mg ions up to a stoichiometry of respecitvely Na11C60 and Mg5C60. This is favored by the large intersitial voids between fullerene molecules in the crystal and by the tendency of C60 to accept electrons from alkali and alkali-earth metals. Sodium-ion and magnesium-ion batteries with anodes based on fullerene and two derivatives, fullerene mixture and hydrogenated fullerene, were assembled and tested. Each material was successfully electrochemically intercalated with sodium and magnesium, with a specific capacity respectively up to 320 mA h / g and 125 mA h / g, although with a reversibility loss after the first cycles. A different approach is developing novel, more performing materials as electrodes for Li-ion batteries. Graphene, thanks to its similarity with graphite, good electrical conductivity and high specific surface area, is a good candidate to improve performances, especially fast rate of charge and discharge, of lithium-ion batteries, and former studies demostrated capability of intercalating graphene and hydrogenated graphene up to 500 mA h / g. In this study, diffusion mechanisms of graphene and hydrogenated graphene are characterized by means of electrochemical impedance spectroscopy, and are coupled, after a proper pre-lithiation, to three different cathodes, in order to obtain high performance full-cells. In particular, hydrogenated graphene boasted an impressive reversible specific capacity with fast charge/discharge capabilities, exceeding 370 mA h g 1 even at the high C-rate of 25C. Moreover, for the first time, thermally exfoliated graphene was coupled to proper cathode materials, in order to study and develop full-cell prototypes, more similar to a commercially viable product. Lastly, one possible approach to solve liquid electrolyte-related safety issues in batteries, is the development of solid electrolytes, which cannot leak out of the batteries, and are more stable at high temperatures or if exposted to air. However, Solid electrolytes cannot compete with liquid electrolytes in terms of room temperature ionic conductivity, which is the capability of allowing the passage of ions. Lithium borohydride is a good solid electrolyte at high temperature, and some derivatives of C60, like Li4C60 and Mg2C60, are superionic conductors at room temperature. Fullerene-borohydiride composite materials with high ionic conductivity were synthesised and characterized. LiBH4-Li6C60 composite showed an ionic conducitivity of 6*10^-6 S / cm at room temperature, which is 100 times higher than pure LiBH4, while NaBH4- Na6C60 boasted an ionic conductivity of 5*10^-5 S / cm at room temperature. Le batterie agli ioni di litio sono lo stato dell'arte nel settore dello stoccaggio di energia. Nonostante abbiano le migliori prestazioni rispetto ad altri tipi di batterie, alcuni problemi sono ancora irrisolti. Il primo è la disponibilità del litio, difficile da riciclare e non molto abbondante in natura. Il secondo è un problema di prestazioni, che non sono ancora paragonabili a quelle dei combustibili fossili. L'ultimo è un problema di sicurezza: le batterie al litio possono scaldarsi, infiammarsi o addirittura esplodere. La maggior parte dei problemi legati alla sicurezza deriva dall'elettrolita, che può fuoriuscire dalle batterie, ed è infiammabile e tossico. Tra le possibili alternative alle batterie agli ioni di litio, le batterie al sodio e al magnesio sono tra le più rilevanti, dal momento che essi sono più abbondanti in natura e più economici. Una delle sfide più grandi per la realizzazione di batterie al sodio e al magnesio, è rappresentata dal trovare materiali adatti a fungere da elettrodo negativo, dato che la grafite, che è il più comune elettrodo negativo nelle batterie al litio, non funziona con sodio e magnesio. Un promettente sostituto è il fullerene C60, che può ospitare sodio e magnesio nella struttura cristallina fino a una stechiometria di Na11C60 e Mg5C60. Ciò è favorito dalle grandi dimensioni dei vuoti interstiziali e dalla tendenza delle molecole di C60 ad accettare elettroni dai metalli alcalini e alcalino-terrosi. Batterie al sodio e magnesio sono state realizzate, utilizzando come elettrodi fullerene C60, fullerene idrogenato e una miscela di C60 e C70. GLi elettrodi sono stati intercalati con successo, con capacità specifiche al primo ciclo pari a 320 mA h / g per le batterie al sodio e 125 mA h / g per quelle al magnesio, sebbene con una perdita di reversibilità nei cicli successivi. Un approccio differente consiste nel realizzare nuove batterie al litio con elettrodi più performanti. Il grafene, grazie alla sua somiglianza con la grafite, un'ottima conduttività elettrica, e un'altissima area superficiale specifica. Pertanto, è un ottimo candidato per migliorare le prestazioni delle batterie, specialmente ad alte correnti. In questo studio, la diffusione del litio nel grafene e nel grafene idrogenato è stata studiata. Inoltre, tali materiali sono stati accoppiati a tre diversi catodi, per realizzare prototipi più simili a sistemi commerciabili. In particolare, prestazioni superiori ai 370 mA h / g sono state ottenute a un rate di carica e scarica di 25C. Infine, un altro possibile approccio è quello di risolvere i problemi legati alla sicurezza tramite lo sviluppo di elettroliti solidi, più stabili e meno tossici di quelli liquidi. Gli elettroliti solidi non possono ancora competere con quelli liquidi a temperatura ambiente in termini di conducibilità ionica, ovvero la proprietà per cui in un elettrolita solido gli ioni si muovono all'interno del materiale. Il boroidruro di litio è un buon conduttore ionico ad alte temperature, mentre alcuni derivati del C60, come Li4C60 e Mg2C60, sono conduttori superionici a temperatura ambiente. Compositi di boroidruri e fulleriti sono stati sintetizzati e caratterizzati, e hanno dimostrato alte conducibilità ioniche, fino a 5*10^-5 S / cm a temperatura ambiente.

Thin-film Solid-State Batteries (TFSSB) is one of most promising and quickly developing fields in modern electrochemical energy storage. Modeling these devices is interesting from theoretical and practical point of view. This paper represents a simulation approach for TFSSB which overcome a major drawback of available mathematical models, i.e. decline in accuracy of the models at high current rates. A one-dimensional electrochemical model, including charge transfer kinetics on the electrolyte-electrode interface, diffusion and migration in electrolyte as well as diffusion in intercalation electrode has been developed and the simulation results are compared to experimental voltage-capacity measurements. A new definition of diffusion coefficient as a function of concentration, based on the experimental measurements, is used to improve the performance of the model. The simulation results fit the available experimental data at low and high discharge currents up to 5 mAh cm −2 . The models show that the cathode diffusion constant is a prime factor limiting the rate capability for TFSSB in particular for ultrafast charging applications. A© 2019 Elsevier B.V.

A solvent-free method that allows thermoplastic solid electrolytes based on poly(ethylene oxide) PEO to be obtained under controlled atmosphere conditions is presented. This method comprises two steps, the first one being the melt compounding of PEO with a filler, able to physically crosslink the polymer and its pelletizing, and the second the pellets’ swelling with an electroactive liquid phase. This method is an adaptation of the step described in previous publications of the preparation of thermoplastic electrolytes by a single melt compounding. In comparison to the single step extrusion methodology, this new method permits employing electroactive species that are very sensitive to atmospheric conditions. The two-step method can also be designed to produce controlled phase-segregated morphologies in the electrolyte, namely polymer-poor and polymer-rich phases, with the aim of increasing ionic conductivity over that of homogeneous electrolytes. An evaluation of the characteristics of the electrolytes prepared by single and two-step procedures is done by comparing membranes prepared by both methods using PEO as a polymeric scaffold and a solution of the room-temperature ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl) imide (EMI TFSI) and the bis(trifluoromethanesulfonyl) imide lithium salt (Li TFSI) as liquid phase. The electrolytes prepared by both methods have been characterized by Fourier transform infrared spectroscopy and optic microscopy profilometry, differential scanning calorimetry, self-creep experiments, and dielectric spectroscopy. In this way, the phase separation, rheology, and ionic conductivity are studied and compared. It is striking how the electrolytes prepared with this new method maintain their solid-like behavior even at 90 °C. Compared to the single step method, the two-step method produces electrolytes with a phase-separated morphology, which results in higher ionic conductivity., This research was funded by H2020-FETOPEN-1-2016-2017 project SALBAGE, Grant Agreement nº766581. F.G. is grateful to CONACYT-SENER for the scholarship granted (CVU 559770/Registro 297710 and S2013/MAE-2800), We acknowledge support by the CSIC Open Access Publication Initiative through its Unit of Information Resources for Research (URICI)

Mg batteries utilizing a Mg metal anode with a high-voltage intercalation cathode define a potential pathway toward energy storage with high energy density. However, the realization of Mg batteries is plagued by the instability of existing electrolytes against the Mg-metal anode and high-voltage cathode materials. One viable solution to this problem is the identification of protective coating materials that could effectively separate the distinct chemistries of the metal-anode and the cathode materials from the electrolyte. Using first-principles calculations we map the electrochemical stability windows for non-redox-active Mg binary and ternary compounds in order to identify potential coating materials for Mg batteries. Our results identify Mg-halides and Mg(BH$_4$)$_2$ as promising anode coating materials based on their significant reductive stability. On the cathode side, we single out MgF$_2$, Mg(PO$_3$)$_2$ and MgP$_4$O$_11$ as effective passivating agents.

The main approach for exploring metastable materials is via trial‐and‐error synthesis, and there is limited understanding of how metastable materials are kinetically stabilized. In this study, a metastable phase superionic conductor, β‐Li3YCl6, is discovered through in situ X‐ray diffraction after heating a mixture of LiCl and YCl3 powders. While Cl− arrangement is represented as a hexagonal close packed structure in both metastable β‐Li3YCl6 synthesized below 600 K and stable α‐Li3YCl6 above 600 K, the arrangement of Li+ and Y3+ in β‐Li3YCl6 determined by neutron diffraction brought about the cell with a 1/√3 a‐axis and a similar c‐axis of stable α‐Li3YCl6. Higher Li+ ion conductivity and lower activation energy for Li+ transport are observed in comparison with α‐Li3YCl6. The computationally calculated low migration barrier of Li+ supports the low activation energy for Li+ conduction, and the calculated high migration barrier of Y3+ kinetically stabilizes this metastable phase by impeding phase transformation to α‐Li3YCl6. This work shows that the combination of in situ observation of solid‐state reactions and computation of the migration energy can facilitate the comprehension of the solid‐state reactions allowing kinetic stabilization of metastable materials, and can enable the discovery of new metastable materials in a short time., A metastable superionic conductor, β‐Li3YCl6, is synthesized by heating a mixture of LiCl and YCl3 powders. The computationally calculated low migration barrier of Li+ supports the low activation energy for Li+ conduction, and the calculated high migration barrier of Y3+ kinetically stabilizes this metastable phase by impeding phase transformation to thermodynamically stable α‐Li3YCl6.

Electrolytes are key components in electrochemical storage systems, which provide an ion-transport mechanism between the cathode and anode of a cell. As battery technologies are in continuous development, there has been growing demand for more efficient, reliable and environmentally friendly materials. Solid-state lithium ion batteries (SSLIBs) are considered as next-generation energy storage systems and solid electrolytes (SEs) are the key components for these systems. Compared to liquid electrolytes, SEs are thermally stable (safer), less toxic and provide a more compact (lighter) battery design. However, the main issue is the ionic conductivity, especially at low temperatures. So far, there are two popular types of SEs: (1) inorganic solid electrolytes (InSEs) and (2) polymer electrolytes (PEs). Among InSEs, sulfide-based SEs are providing very high ionic conductivities (up to 10−2 S/cm) and they can easily compete with liquid electrolytes (LEs). On the other hand, they are much more expensive than LEs. PEs can be produced at less cost than InSEs but their conductivities are still not sufficient for higher performances. This paper reviews the most efficient SEs and compares them in terms of their performances and costs. The challenges associated with the current state-of-the-art electrolytes and their cost-reduction potentials are described.