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Organic cations are essential components of locally concentrated ionic liquid electrolytes (LCILEs), but receive little attention. Herein, we demonstrate their significant influence on the electrochemical performance of lithium metal batteries via a comparison study of two LCILEs employing either 1‑butyl‑1-methylpyrrolidinium cation (Pyr14+) or 1-ethyl-3-methylimidazolium cation (Emim+). It is demonstrated that the structure of the organic cation in LCILEs has only a limited effect on the Li+- bis(fluorosulfonyl)imide anion (FSI−) coordination. Nonetheless, the coordination of FSI− with the organic cations is different. The less coordination of FSI− to Emim+ than to Pyr14+ results in the lower viscosity and faster Li+ transport in the Emim+-based electrolyte (EmiBE) than the Pyr14+-based electrolyte (PyrBE). Additionally, the chemical composition of the solid-electrolyte interphase (SEI) formed on lithium metal is affected by the organic cations. A more stable SEI growing in the presence of Emim+ leads to a higher lithium plating/stripping Coulombic efficiency (99.2%). As a result, Li/EmiBE/LiNi0.8Mn0.1Co0.1O2 cells exhibit a capacity of 185 mAh g−1 at 1C discharge (2 mA cm−2) and capacity retention of 96% after 200 cycles. Under the same conditions, PyrBE-based cells show only 34 mAh g−1 capacity with 39.6% retention.

A cost-effective and reliable technology allowing extreme miniaturization of batteries into glass chips and electronic packages has been developed, employing a dispense-print process for battery electrodes and liquid electrolyte. Lithium-ion micro-batteries (active area 6 × 8 mm2, 0.15–0.3 mAh) with interdigitated electrodes were fabricated, tested and finally compared with the traditional battery architecture of stacked electrodes. Commercial graphite and lithium titanate anode as well as layered nickel cathode materials were used. All the processes for the micro-battery fabrication were established during this work; in particular the micro fluidic electrolyte filling process that allows simultaneous electrolyte supply to all cells on a planar substrate. Electrode mass reproducibility was sufficient for adequate electrode balancing. Current capability similar to the conventional face-to-face electrode configuration was achieved with interdigital electrodes that can be fabricated much easily on a substrate level. The cells were successfully cycled; several 100 cycles can be achieved. Additional results of life-time characteristics and electrochemical impedance spectroscopy are presented as well. These rechargeable micro-batteries can be used for future extremely miniaturized electronic products.

FSI

This chapter analyzes state-of-the-art and progresses on nanomaterials’ utilization for multivalent-ion (e.g., Mg, Ca, Zn, Al) battery applications. The work comprises four sections, namely carbon-based, metal-based, metal oxide-based, and metal sulfide-based nanomaterials. These four classes of materials are evaluated in terms of structure, morphology, and electrochemical energy storage properties.

Herein, we report a comparison of aluminum graphite dual-ion cells (AGDICs) electrochemical characteristics employing the conventional 1-ethyl-3-methylimidazolium chloride:aluminum trichloride (EMIMCl : AlCl3) electrolyte and two popular deep eutectic solvents (DESs), namely urea : AlCl3 and acetamide:AlCl3. The three electrolytes' characteristics have been evaluated in terms of Al-stripping deposition capability and cycling behavior in AGDICs. The results evidence the EMIMCl : AlCl3's Al-stripping deposition and rate capability in AGDICs superior characteristics addressed to the lower viscosity and higher conductivity with respect to the urea : AlCl3 and acetamide:AlCl3. On the other hand, the urea : AlCl3 guarantees a much higher columbic efficiency in AGDICs, thanks to the superior electrochemical window stability.

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Rechargeable graphite dual-ion batteries are extremely appealing for grid-level stationary storage of electricity, thanks to the low-cost and high-performance metrics, such as high-power density, energy efficiency, long cycling life, and good energy density. An in-depth understanding of the anion intercalation mechanism in graphite is fundamental for the design of highly efficient systems. In this work, a comparison is presented between pyrolytic (PG) and natural (NG) graphite as positive electrode materials in rechargeable aluminum batteries, employing an ionic liquid electrolyte. The two systems are characterized by operando synchrotron energy-dispersive X-ray diffraction and time-resolved computed tomography simultaneously, establishing a powerful characterization methodology, which can also be applied more in general to carbon-based energy-related materials. A more in-depth insight into the AlCl4−/graphite intercalation mechanism is obtained, evidencing a mixed-staged region in the initial phase and a two-staged region in the second phase. Moreover, strain analysis suggests a correlation between the irreversibility of the PG electrode and the increase of the inhomogenous strain. Finally, the imaging analysis reveals the influence of graphite morphology in the electrode volume expansion upon cycling., In‐depth insight into the AlCl4−/graphite intercalation mechanism is obtained by operando synchrotron energy‐dispersive X‐ray diffraction and time‐resolved computed tomography simultaneously, establishing a powerful characterization methodology, which can also be applied more in general to battery‐related materials. image

Highly concentrated glyme‐based electrolytes are friendly to a series of negative electrodes for potassium‐based batteries, including potassium metal. However, their compatibility with positive electrodes has been rarely explored. In this work, the influence of the molar fraction of potassium bis(trifluoromethanesulfonyl)imide dissolved in glyme on the cycling ability of K/bilayered‐V2O5 batteries has been investigated. At high salt concentration, the interaction between K+ ions with the glyme is strengthened, leading to a limited number of free glyme molecules. Therefore, the anodic decomposition of the electrolyte solvent, as well as the dissolution of the Al current collectors, is effectively suppressed, resulting in the improved cycling ability of the K/bilayered‐V2O5 cells. In these cells, the positive electrode active material exhibits reversible capacities of 93 and 57 mAh g−1 at specific current densities of 50 and 1000 mA g−1, respectively. After 200 charge‐discharge cycles at 500 mA g−1, the cell retains 94 % of the initial capacity. The promising rate performance and capacity retention demonstrate the importance of proper electrolyte engineering for the K/bilayered‐V2O5 batteries, and the good compatibility of highly concentrated glyme‐based electrolytes with positive electrode materials for potassium batteries.

V2O5, one of the earliest intercalation-type cathode materials investigated as a Li+ host, is characterized by an extremely high theoretical capacity (441 mAh g-1). However, the fast capacity fading upon cycling in conventional carbonate-based electrolytes is an unresolved issue. Herein, we show that using a LiTFSI/tetraglyme (1:1 in mole ratio) electrolyte yields a highly enhanced cycling ability of V2O5 (from 20% capacity retention to 80% after 100 cycles at 50 mA g-1 within 1.5-4.0 V vs Li+/Li). The improved performance mostly originates from the V2O5 electrode itself, since refreshing the electrolyte and the lithium electrode of the cycled cells does not help in restoring the V2O5 electrode capacity. Electrochemical impedance spectroscopy (EIS), post-mortem scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) spectroscopy, and X-ray photoelectron spectroscopy (XPS) have been employed to investigate the origin of the improved electrochemical behavior. The results demonstrate that the enhanced cyclability is a consequence of a thinner but more stable cathode-electrolyte interphase (CEI) layer formed in LiTFSI/tetraglyme with respect to the one occurring in 1 M LiPF6 in EC/DMC (1:1 in weight ratio, LP30). These results show that the cyclability of V2O5 can be effectively improved by simple electrolyte engineering. At the same time, the uncovered mechanism further reveals the vital role of the CEI on the cyclability of V2O5, which can be helpful for the performance optimization of vanadium-oxide-based batteries.

There is growing interest in the rational design of electrolytes for multivalent-ion batteries by tuning the molecular-level interactions of solvate species present in the electrolytes. Herein, we report our effort to control Ca-ion speciation in ionic liquid (IL) based electrolytes through the design of alkoxy-functionalized cations. Quantitative analysis reveals that the alkoxy-functionalized ammonium cation (N$_{07}$$^{+}$), bearing seven ether oxygen atoms, can effectively displace the bis(trifluoromethanesulfonyl)imide anion (TFSI$^{-}$) from the Ca$^{2+}$ ion coordination sphere, facilitating the reversible Ca deposition/stripping process. More importantly, post-analysis of Ca deposits surface chemistry and density functional theory calculations of Ca-ion speciation indicate the formation of an organic-rich, but inorganic-poor solid electrolyte interphase layer, which enables Ca$^{+2}$ ion diffusion rather than passivating the Ca metal electrode. Finally, as a proof-of-concept, a prototype Ca/V$_{2}$O$_{5}$ cell using the optimized IL-based electrolyte ([Ca(BH$_{4}$)$_{2}$]$_{0.05}$ [N$_{07}$TFSI]$_{0.95}$) is demonstrated for the first time, exhibiting a remarkable initial discharge capacity of 332 mA h g$^{-1}$ and reversible capacity of 244 mA h g$^{-1}$.

Sodium batteries (SBs) are seen as a sustainable alternative for electrochemical energy storage. However, progresses on electrolytes is required to enable future commercialization. A comprehensive review of the status, and the prospects of various Na‐ion electrolytes, including solvents, salts, additives, electrode/electrolyte interphases, and potential hazards, is presented. For sodium (Na)‐rechargeable batteries to compete, and go beyond the currently prevailing Li‐ion technologies, mastering the chemistry and accompanying phenomena is of supreme importance. Among the crucial components of the battery system, the electrolyte, which bridges the highly polarized positive and negative electrode materials, is arguably the most critical and indispensable of all. The electrolyte dictates the interfacial chemistry of the battery and the overall performance, having an influence over the practical capacity, rate capability (power), chemical/thermal stress (safety), and lifetime. In‐depth knowledge of electrolyte properties provides invaluable information to improve the design, assembly, and operation of the battery. Thus, the full‐scale appraisal of both tailored electrolytes and the concomitant interphases generated at the electrodes need to be prioritized. The deployment of large‐format Na‐based rechargeable batteries also necessitates systematic evaluation and detailed appraisal of the safety‐related hazards of Na‐based batteries. Hence, this review presents a comprehensive account of the progress, status, and prospect of various Na+‐ion electrolytes, including solvents, salts and additives, their interphases and potential hazards., publishedVersion

Vanadium oxides have been recognized to be among the most promising positive electrode materials for aqueous zinc metal batteries (AZMBs). However, their underlying intercalation mechanisms are sti...

Sulfurized polyacrylonitrile (SPAN) is the most promising cathode for next-generation lithium–sulfur (Li–S) batteries due to the much improved stability. However, the molecular structure and reaction mechanism have not yet been fully understood. Herein, we present a new take on the structure and mechanism to interpret the electrochemical behaviors. We find that the thiyl radical is generated after the cleavage of the S–S bond in molecules in the first cycle, and then a conjugative structure can be formed due to electron delocalization of the thiyl radical on the pyridine backbone. The conjugative structure can react with lithium ions through a lithium coupled electron transfer process and form an ion-coordination bond reversibly. This could be the real reason for the superior lithium storage capability, in which the lithium polysulfide may not be formed. This study refreshes current knowledge of SPAN in Li–S batteries. In addition, the structural analysis is applicable to analyze the current organic catho...

Herein we report a novel study on the reaction mechanism of non aqueous aluminum graphite cell chemistry employing 1 ethyl 3 methylimidazolium chloride aluminum trichloride EMIMCl AlCl3 as the electrolyte. This work highlights new insights into the reversibility of the anion intercalation chemistry besides confirming its outstanding cycle life exceeding 2000 cycles, corresponding to more than 5 months of cycling test. The reaction mechanism, involving the intercalation of AlCl4 in graphite, has been fully characterized by means of ex situ X ray diffraction XRD , X ray photoelectron spectroscopy XPS , X ray absorption near edge structure spectroscopy XANES and small angle X ray scattering SAXS , evidencing the accumulation of anionic species into the cathode as the main factor responsible for the slight initial irreversibility of the electrochemical process

This work presents an enhanced hydrometallurgical process for recycling lithium ion batteries. First, end-of-life batteries were processed in a physical pre-treatment plant to obtain a representative electrode material. The resulting leachate was purified forth by iron-precipitation, liquid–liquid extractions, and an innovative Li–Na separation, in order to obtain valuable products. These products include high-grade graphite, cobalt oxide (Co3O4, purity 83%), cobalt oxalate (CoC2O4, purity 96%), nickel oxide (NiO, purity 89%), and lithium carbonate (Li2CO3, purity 99.8%). The recovery rate was quantitative for graphite, between 80% and 85% for cobalt depending on the nature of the recovery method, 90% for nickel, and 72% for lithium. Secondary streams were also valorized to obtain sodium sulfate (Na2SO4, purity 96%), and MnCoFe2O4 magnetic nano-sorbents according to the zero-waste concept. In order to close the loop, recycled Co3O4 and NiO were used as conversion-type anode materials for advanced lithium ion batteries showing promising performances.

Enhanced solid-state ionic diffusion for high-power Na-ion and K-ion hybrid capacitors (SIHCs and PIHCs) is usually attained via tailoring anode materials to the nanoscale, which inevitably require...

Herein we report on a detailed investigation of the irreversible capacity in the first cycle of pyrolytic graphite electrodes in aluminum batteries employing 1-ethyl-3-methylimidazolium chloride:aluminum trichloride (EMIMCl:AlCl3) as electrolyte. The reaction mechanism, involving the intercalation of AlCl4 in graphite, has been fully characterized by correlating the micro/nanostructural modification to the electrochemical performance. To achieve this aim a combination of X-ray diffraction (XRD), small angle X-ray scattering (SAXS) and computed tomography (CT) has been used. The reported results evidence that the irreversibility is caused by a very large decrease in the porosity, which consequently leads to microstructural changes resulting in the trapping of ions in the graphite. A powerful characterization methodology is established, which can also be applied more generally to carbon-based energy-related materials. Introduction

Aluminum batteries are considered compelling electrochemical energy storage systems because of the natural abundance of aluminum, the high charge storage capacity of aluminum of 2980 mA h g−1/8046 mA h cm−3, and the sufficiently low redox potential of Al3+/Al. Several electrochemical storage technologies based on aluminum have been proposed so far. This review classifies the types of reported Al-batteries into two main groups: aqueous (Al-ion, and Al-air) and non-aqueous (aluminum graphite dual-ion, Al-organic dual-ion, Al-ion, and Al-sulfur). Specific focus is given to Al electrolyte chemistry based on chloroaluminate melts, deep eutectic solvents, polymers, and “chlorine-free” formulations., Journal of Power Sources, 481, ISSN:0378-7753, ISSN:1873-2755

Herein we studied a rechargeable sodium–oxygen cell operating at room temperature and employing a cathode comprising multi-walled carbon nanotubes coated on a gas diffusion layer. The oxygen reduction reaction (ORR) is investigated and improved by optimizing the cathode configuration. We demonstrated by means of X-ray diffraction (XRD) and scanning electron microscopy (SEM) measurements that, using a low-volatile tetraethylene glycol dimethyl ether (TEG-DME)-sodium trifluoromethanesulfonate (NaCF3SO3) electrolyte solution, the major discharge product is NaO2. Moreover, we originally demonstrated that controlled amount of superoxide formed at the cathode side by discharge facilitates the oxygen evolution reaction (OER), thus resulting in a charge-discharge polarization as low as 400 mV. The developed system can deliver a capacity of 500 mAh g−1 with an energy efficiency as high as 83% for 60 charge-discharge cycles. The data here reported represent a step-forward in the development of an efficient sodium-air battery.

Separators and electrolytes provide electronic blockage and ion permeability between the electrodes in electrochemical cells. Nowadays, their performance and cost is often even more crucial to the commercial use of common and future electrochemical cells than the chosen electrode materials. Hence, at the present, many efforts are directed towards finding safe and reliable solid electrolytes or liquid electrolyte/separator combinations. With this comprehensive review, the reader is provided with recent approaches on this field and the fundamental knowledge that can be helpful to understand and push forward the developments of new electrolytes for rechargeable batteries. After presenting different types of separators as well as the main hurdles that are associated with them, this work focuses on promising material classes and concepts for next-generation batteries. First, chemical and crystallographic concepts and models for the description and improvement of the ionic conductivity of bulk and composite solid electrolytes are outlined. To demonstrate recent perspectives, research highlights have been included in this work: magnesium borohydride-based complexes for solid-state Mg batteries as well as all-in-one rechargeable SrTiO3 single-crystal energy storage. Furthermore, ionic liquids pose a promising safe alternative for future battery cells. An overview on their basic principles and use is given, demonstrating their applicability for Li-ion systems as well as for so-called post-Li chemistries, such as Mg- and Al-ion batteries.

An efficient lithium-ion battery was assembled by using an enhanced sulfur-based cathode and a silicon oxide-based anode and proposed as an innovative energy-storage system. The sulfur-carbon composite, which exploits graphene carbon with a 3 D array (3DG-S), was synthesized by a reduction step through a microwave-assisted solvothermal technique and was fully characterized in terms of structure and morphology, thereby revealing suitable features for lithium-cell application. Electrochemical tests of the 3DG-S electrode in a lithium half-cell indicated a capacity ranging from 1200 to 1000 mAh g-1 at currents of C/10 and 1 C, respectively. Remarkably, the Li-alloyed anode, namely, Liy SiOx -C prepared by the sol-gel method and lithiated by surface treatment, showed suitable performance in a lithium half-cell by using an electrolyte designed for lithium-sulfur batteries. The Liy SiOx -C/3DG-S battery was found to exhibit very promising properties with a capacity of approximately 460 mAh gS-1 delivered at an average voltage of approximately 1.5 V over 200 cycles, suggesting that the characterized materials would be suitable candidates for low-cost and high-energy-storage applications.

Cathode configurations reported herein are alternative to the most diffused ones for application in lithium-oxygen batteries, using an ionic liquid-based electrolyte. The electrodes employ high surface area conductive carbon as the reaction host, and polytetrafluoroethylene as the binding agent to enhance the oxygen reduction reaction (ORR)/oxygen evolution reaction (OER) reversibility. Roll-pressed, self-standing electrodes (SSEs) and thinner, spray deposited electrodes (SDEs) are characterized in lithium-oxygen cells using an ionic liquid (IL) based electrolyte formed by mixing lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) salt and N,N-diethyl-N-(2-methoxyethyl)-N-methylammonium bis(trifluoromethanesulfonyl)imide (DEMETFSI). The electrochemical results reveal reversible reactions for both electrode configurations, but improved electrochemical performance for the self-standing electrodes in lithium-oxygen cells. These electrodes show charge/discharge polarizations at 60 °C limited to 0.4 V, with capacity up to 1 mAh cm-2 and energy efficiency of about 88 %, while the spray deposited electrodes reveal, under the same conditions, a polarization of 0.6 V and energy efficiency of 80 %. The roll pressed electrode combined with the DEMETFSI-LiTFSI electrolyte and a composite Lix Sn-C alloy anode forms a full Li-ion oxygen cell showing extremely limited polarization, and remarkable energy efficiency.

Here we report a low polarization, catalyst-free lithium–oxygen battery using mesoporous carbon electrode. BET analysis, SEM and TEM images evidence that the carbon material has surface area as high as 1500 m 2 g -1 and a uniform distribution of nanometric pores. Furthermore, X-ray diffraction analysis and TEM images of the reaction products show that the favourable effect of the mesoporous carbon is due to the formation of amorphous nano-particles of lithium peroxide during the electrochemical process. The results of this study clearly indicate the important role of the carbon matrix in determining a favourable morphology of the lithium–oxygen reaction product that leads to enhanced cell behaviour.

An advanced lithium ion battery using nanostructured tin–carbon lithium alloying anode and high voltage LiNi 0.5 Mn 1.5 O 4 spinel-type cathode is studied, with particular focus to the low temperature range. The stable behavior of the battery is assured by the use of an electrolyte media based on a LiPF 6 salt dissolved in EC-DEC-DMC, i.e. a mixture particularly suitable for the low temperature application. Cycling tests, both in half cells and in full lithium ion battery using the Sn–C anode and the LiNi 0.5 Mn 1.5 O 4 cathode, performed in a temperature range extending from room temperature to −30 °C, indicate that the electrode/electrolyte configuration here adopted may be suitable for effective application in the lithium ion battery field. The full cell, cycled at −5 °C, shows stable capacity of about 105 mAh g −1 over more than 200 charge–discharge cycles that is a relevant performance considering the low temperature used for the study.

A cost effective and reliable technology for the fabrication of electrochemical test cell arrays for battery materials investigation, based on batch fabricated glass micro packages was developed and tested. Semi-automatic micro dispensing was investigated as a process for the standardized application of different electrode materials and SiO 2 -based separator. The process shows sufficient reproducibility over the whole range of investigated materials, especially for the cells with interdigital (side-by-side) electrodes. Such setup gives rise to an improved reliability and reproducibility of electrochemical experiments. The economic fabrication of our test chips by batch processing allows for their single-use in electrochemical experiments, herby preventing contamination issues due to repeated use as in conventional laboratory test cells. In addition, the integration of micro pseudo reference electrodes was demonstrated. Thus, the presented test cell array together with the developed electrode/electrolyte deposition technology represents a highly efficient tool for combinatorial and high throughput testing of battery materials on system level (full cell tests). The method will speed up electrochemical materials research significantly.

A cost effective and reliable technology allowing extreme miniaturization of batteries into silicon, glass chips and electronic packages has been developed, employing a dispense-print process for battery electrodes and liquid electrolyte. Lithium-ion micro batteries (active area 6×8 mm2, 0.2–0.4 mAh) with interdigitated electrodes and glass housing were fabricated, tested and finally compared with the traditional battery architecture of stacked electrodes. All processes for micro battery fabrication were established; in particular a micro fluidic electrolyte filling process that allows simultaneous electrolyte supply of all cells on a planar substrate. Electrode mass reproducibility was sufficient for adequate electrode balancing. Current capability similar to the conventional face-to-face electrode configuration was achieved with interdigital electrodes. The cells were successfully cycled; several 100 cycles can be achieved.

Herein we report a novel synthetic procedure for the preparation of a SiOx-based nano-composite involving gelification of resorcinol-formaldehyde and tetraethyl orthosilicate. The composite is characterized as anode material in lithium-ion battery. The micrometric, amorphous material has a characteristic nanostructured configuration and shows an electrochemical process involving both the Li-Si alloying and the Li-insertion into the hard carbon matrix. The electrode reveals in lithium half-cell a relatively low impedance and a reversible capacity ranging from 650 mAh g-1 at the lower current to 400 mAh g-1 at high current regimes, with cycle life extending to 200 cycles. The anode is combined with a high voltage, LiNi0.5Mn1.5O4 spinel cathode in a 4.3 V lithium ion battery delivering a capacity of about 115 mAh g-1 and operating at the high rate of 5C. The suitable synthesis pathway, the low cost and the promising electrochemical behavior suggest the nano-composite anode for application in high performance lithium-ion battery.

In this paper we investigate in details the changes occurring in the lithium–oxygen cell during operation in a tetraglyme-base electrolyte, in terms of electrochemical behavior and of carbon electrode morphology. The study evidences a decrease of the cell polarization and impedance during cycling associated with a morphological change of the carbon electrode, as demonstrated by SEM images. We attribute the change of the electrode morphology to the already known carbon oxidation process, here resulting in an increased porosity favoring the reversible electrochemical process. The results here reported shed light on important aspects to be considered in order to better understand the complex behavior of the lithium–oxygen battery. Keywords: Lithium–oxygen battery, Tetraglyme-electrolyte, Impedance spectroscopy, Cathode morphology

A critical overview of the latest developments in the aluminum battery technologies is reported. The substitution of lithium with alternative metal anodes characterized by lower cost and higher abundance is nowadays one of the most widely explored paths to reduce the cost of electrochemical storage systems and enable long-term sustainability. Aluminum based secondary batteries could be a viable alternative to the present Li-ion technology because of their high volumetric capacity (8040 mAh cm(-3) for Al vs 2046 mAh cm(-3) for Li). Additionally, the low cost aluminum makes these batteries appealing for large-scale electrical energy storage. Here, we describe the evolution of the various aluminum systems, starting from those based on aqueous electrolytes to, in more details, those based on non-aqueous electrolytes. Particular attention has been dedicated to the latest development of electrolytic media characterized by low reactivity towards other cell components. The attention is then focused on electrode materials enabling the reversible aluminum intercalation-deintercalation process. Finally, we touch on the topic of high-capacity aluminum-sulfur batteries, attempting to forecast their chances to reach the status of practical energy storage systems.

Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugänglich. This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively. Advanced ionic liquid-based electrolytes are herein characterized for application in high performance lithium-ion batteries. The electrolytes based on either N-butyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl) imide (Pyr(14)TFSI), N-butyl-N-methylpyrrolidinium bis(fluoro-sulfonyl) imide (Pyr(14)FSI), N-methoxy-ethyl-N-methylpyrrolidinium bis(trifluoromethane-sulfonyl) imide (Pyr(12O1)TFSI) or N-N-diethyl-N-methyl-N-(2methoxyethyl) ammonium bis(trifluoromethanesulfonyl) imide (DEMETFSI) ionic liquids and lithium bis(trifluoromethanesulfonyl) imide (LiTFSI) salt are fully characterized in terms of ionic conductivity, viscosity, electrochemical properties and lithium-interphase stability. All IL-based electrolytes reveal suitable characteristics for application in batteries. Lithium half-cells, employing a LiFePO4 polyanionic cathode, show remarkable performance. In particular, relevant efficiency and rate-capability are observed for the Py14FSI-LiTFSI electrolyte, which is further characterized for application in a lithium-ion battery composed of the alloying Sn-C nanocomposite anode and LiFePO4 cathode. The IL-based full-cell delivers a maximum reversible capacity of about 160 mA h g(-1) (versus cathode weight) at a working voltage of about 3 V, corresponding to an estimated practical energy of about 160 W h kg(-1). The cell evidences outstanding electrochemical cycle life, i.e., extended over 2000 cycles without signs of decay, and satisfactory rate capability. This performance together with the high safety provided by the IL-electrolyte, olivine-structure cathode and Li-alloying anode, makes this cell chemistry well suited for application in new-generation electric and electronic devices.

In this paper, we report an advanced long-life lithium ion battery, employing a Pyr14 TFSI-LiTFSI non-flammable ionic liquid (IL) electrolyte, a nanostructured tin carbon (Sn-C) nanocomposite anode, and a layered LiNi1/3 Co1/3 Mn1/3 O2 (NMC) cathode. The IL-based electrolyte is characterized in terms of conductivity and viscosity at various temperatures, revealing a Vogel-Tammann-Fulcher (VTF) trend. Lithium half-cells employing the Sn-C anode and NMC cathode in the Pyr14 TFSI-LiTFSI electrolyte are investigated by galvanostatic cycling at various temperatures, demonstrating the full compatibility of the electrolyte with the selected electrode materials. The NMC and Sn-C electrodes are combined into a cathode-limited full cell, which is subjected to prolonged cycling at 40 °C, revealing a very stable capacity of about 140 mAh g(-1) and retention above 99 % over 400 cycles. The electrode/electrolyte interface is further characterized through a combination of electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM) investigations upon cell cycling. The remarkable performances reported here definitively indicate that IL-based lithium ion cells are suitable batteries for application in electric vehicles.

In this paper, we propose a new electrolyte formed by dissolving lithium-bis-(trifluoromethanesulfonyl)-imide (LiTFSI) salt in a long chain glyme, i.e. poly(ethylene glycol)500-dimethylether (PEG500DME) mixed with methyl butyl pyrrolidinium-bis-(trifluoromethanesulfonyl)-imide (Pyr14TFSI) ionic liquid. The electrolyte composition ensures both very low volatility and good performance as demonstrated by thermal analysis and electrochemical tests. The selected solution is efficiently employed as the electrolyte both in a lithium–oxygen half-cell, and in a full lithium-ion oxygen battery using a Li–Sn–C nanostructured composite anode, thus suggesting the suitability of the polyethylene glyme mixed with the ionic liquid for application in high-energy storage systems.

Herein we report the characteristics of a lithium-oxygen battery using a solid polymer membrane as the electrolyte separator. The polymer electrolyte, fully characterized in terms of electrochemical properties, shows suitable conductivity at room temperature allowing the reversible cycling of the Li-O2 battery with a specific capacity as high as 25,000 mAh gC−1 reflected in a surface capacity of 12.5 mAh cm−2. The electrochemical formation and dissolution of the lithium peroxide during Li-O2 polymer cell operation is investigated by electrochemical techniques combined with X-ray diffraction study, demonstrating the process reversibility. The excellent cell performances in terms of delivered capacity, in addition to its solid configuration allowing the safe use of lithium metal as high capacity anode, demonstrate the suitability of the polymer lithium-oxygen as high-energy storage system.

The replacement of the combustion-engine by sustainable electric or hybrid vehicles, may effectively limit environmental issues such as the global warming greenhouse-gas emission and pollution [1-2]. Lithium-ion battery represents the most promising candidate due to its high energy density, conventionally of about 180 Wh kg-1 that may assure a driving range of 150 km by single charge, i.e. acceptable value, however far from that granted by the conventional combustion engine vehicles. The lithium oxygen system, can theoretically allow to obtain an energy density of 1000 Wh kg-1, i.e. a value that may increase the driving range by single charge [3]. The applicability of the lithium air batteries is limited by several drawbacks, such as the poor electrolyte stability, the short cycle life and the low energy efficiency due to high charge-discharge polarization [4]. A deep knowledge of the lithium-oxygen reaction mechanism [5] and the identification of a stable electrolyte [6] play important role fundamental in allowing the practical application of the system. Furthermore, the safety concerns associated to the reactivity of the lithium metal anode are still hindering the application of the lithium-oxygen battery [7]. We report a Li/O2 cell exploiting an ionic liquid(IL)-based, N-Methyl-N-Butyl-Pyrrolidinium Bis-(trifluoromethanesulfonyl)-Imide Lithium bis-(trifluormethanesulfonyl)-imide, Pyr14TFSI-LiTFSI electrolyte. The use of non-flammable IL-based electrolyte stable up to a 300-400 °C resulted in an improved safety level of the battery [8]. In addition, the ionic-liquid electrolyte allows a fast kinetics of the lithium oxygen electrochemical process, thus lead to an high energy efficiency. The results here obtained, and reported in summary in the figure evidence low cell polarization, most likely due to the reduced particle size of the discharged products [9]. The replacement of the reactive lithium metal by an alternative, safe anode material may be required to further enhance the lithium oxygen cell characteristics [10]. Herein, we employed an alternative, nanostructured tin-carbon composite instead of lithium metal, in lithium ion-oxygen cell characterized in terms of electrochemical properties, focusing particular attention to the study of the oxygen cross-over process. [1] B. Scrosati, J. Hassoun, Y.-K. Sun, Ener. Environ. Sci., 4, 3287 (2011). [2] P. Myounggu, S. Heeyoung, L. Hyungbok, L. Junesoo, C. Jaephil, Adv. Energy Mater., 2, 780 (2012). [3] P. G. Bruce, S. A. Freunberger, L. J. Hardwick, J.-M. Tarascon, Nat. Mater. 11, 19, (2012). [4] Y.-C. Lu, B. M. Gallant, D. G. Kwabi, J. R. Harding, R. R. Mitchell, M. S. Whittingham, Y. Shao-Horn, Energy Environ. Sci., 6, 750, (2013). [5] M. Leskes, N.E. Drewett, L. J. Hardwick, P. G. Bruce, G. R. Goward, C. P. Grey, Angew. Chem. Int. Ed. 51, 8560, (2012). [6] H.-G. Jung, J. Hassoun, J.-B. Park, Y.-K. Sun, B. Scrosati, Nat. Chem. 4, 579, (2012). [7] J.-L. Shui, J.S. Okasinski, P. Kenesei, H.A. Dobbs, D. Zhao, J.D. Almer, D.-J. Liu, Nat. Commun., 4, 2255, (2013). [8] S. Randstrom, G. B. Appetecchi, C. Lagergren, A. Moreno, S. Passerini, Electrochim. Acta 53, 1837, (2007). [9] G.A. Elia, J. Hassoun, W.-J. Kwak, Y.-K. Sun, B. Scrosati, F. Mueller, D. Bresser, S. Passerini, P. Oberhumer, N. Tsiouvaras, J. Reiter, (2014) Nano Lett., 14, 6572, (2014). [10] J. Hassoun, H.-G. Jung, D.-J. Lee, J.-B. Park, K. Amine, Y.-K. Sun, B. Scrosati Nano Lett., 12, 5775, (2012) Figure 1

Batteries based on alkali-ions, such as lithium, sodium and potassium are considered the energy storage systems of choice for the next generation applications, such as electrified mobility and supply for renewable energy storage [1]. These systems are, in principle, light, efficient and potentially capable to meet several of the targets characterizing the emerging markets [2]. However, the use of the alkali-metal anode is definitely hindered by severe safety issues, including extreme reactivity with the electrolyte, eventual dendrite formation and cell short-circuit, leading to possible heating, thermal runway and fire [3,4]. Therefore, the severe requirements of the modern society triggered the replacement of the metallic anode by alternative materials characterized by higher safety content, in particular based on carbon [5], alloys [6] and metal oxides [7]. This radical change, partially succeeding in particular for lithium [6], is however still limited to few examples of efficient systems, employed for practical energy storage [1,3], such as Graphite/LCO, Graphite/LFP and Graphite/LNMC. Within this paper we developed a series of lithium-ion and sodium-ion batteries, including metal alloying [8], conversion [9] and graphene [10] anodes, high voltage spinel [11], olivine [12], sulfur [13,14] and oxygen [15] cathodes, and ionic liquid electrolyte [10,16] considered of interest for practical employment as alternative, safe and high energy storage systems for next generation applications. Figure: examples of various sodium and lithium ion cells in which the metal anode has been replaced by alternative materials References [1] D. Larcher, J-M. Tarascon, Nature Chemistry, 2015, 7, 19. [2] J. B. Goodenough, K.-S. Park, JACS, 2013, 135, 116. [3] J.-M. Tarascon, M. Armand, Nature, 2001, 414, 359. [4] V. L. Chevrier, G. Ceder, J. Electrochem. Soc., 2011, 158, 9, A1011. [5] M. Winter, J. O. Besenhard, M. E. Spahr, P. Novak, Adv. Mater., 1998, 10, 725. [6] J. Hassoun, P. Reale, B. Scrosati, J. Mater. Chem, 2007, 17, 3668. [7] J. Cabana, L. Monconduit, D. Larcher, M. R. Palacìn, Adv. Energy Mater., 2010, 22, E170. [8] J. Hassoun, S. Panero, P. Reale, and B. Scrosati, Adv. Mater., 2009, 21, 4808 [9] R. Verrelli, J. Hassoun, A. Farkas, T. Jacob, B. Scrosati, J. Mater. Chem. A, 2013, 1, 15329 [10] J. Hassoun, F. Bonaccorso, M. Agostini, M. Angelucci, M.G. Betti, R. Cingolani, M. Gemmi, C. Mariani, S. Panero, V. Pellegrini, B. Scrosati, Nano Letters, 2014, 14, 4901 [11] R. Verrelli, B. Scrosati, Y.-K. Sun, J. Hassoun, ACS Appl. Mater. Interfaces, 2014, 6, 5206 [12] I. Hasa, J. Hassoun, Y.-K. Sun, B. Scrosati, ChemPhysChem, 2014, 15, 2152 [13] M. Agostini, J. Hassoun, Scientific Reports, 20155, 7591 [14] D.-J. Lee, J.-W. Park, I. Hasa, Y.-K. Sun, B. Scrosati, J. Hassoun, J. Mater. Chem. A, 2013, 1, 5256 [15] G.A. Elia, R. Bernhard, J. Hassoun, RSC Advances, DOI: 10.1039/c4ra17277a [16] D. Di Lecce, S. Brutti, S. Panero, J. Hassoun, Materials Letters, 2015, 139, 329 Figure 1

International audience; A novel lithium-ion/oxygen battery employing Pyr(14)FSI-LiTESI as the electrolyte and nanostructured LixSn-C as the anode is reported. The remarkable energy content of the oxygen cathode, the replacement of the lithium metal anode by a nanostructured stable lithium-alloying composite, and the concomitant use of nonflammable ionic liquid-based electrolyte result in a new and intrinsically safer energy storage system. The lithium-ion/oxygen battery delivers a stable capacity of 500 mAh g(-1) at a working voltage of 2.4 V with a low charge-discharge polarization. However, further characterization of this new system by electrochemical impedance spectroscopy, scanning electron microscopy, and energy-dispersive X-ray spectroscopy reveals the progressive decrease of the battery working voltage, because of the crossover of oxygen through the electrolyte and its direct reaction with the LixSn-C anode.

In this paper we report a new, high performance lithium-ion battery comprising a nanostructured Sn-C anode and Li[Li0.2Ni0.4/3Co0.4/3Mn1.6/3]O2 (lithium-rich) cathode. This battery shows highly promising long-term cycling stability for up to 500 cycles, excellent rate capability, and a practical energy density, which is expected to be as high as 220 Wh kg(-1) at the packaged cell level. Considering the overall performance of this new chemistry basically related to the optimized structure, morphology, and composition of the utilized active materials as demonstrated by XRD, TEM, and SEM, respectively, the system studied herein is proposed as a suitable candidate for application in the lithium-ion battery field.