Unprotected Organic Cations─The Dilemma of Highly Li-Concentrated Ionic Liquid Electrolytes.

Highly Li-concentrated electrolytes have been widely studied to harness their uniquely varying bulk and interface properties that arise from their distinctive physicochemical properties and coordination structures. Similar strategies have been applied in the realm of ionic liquid electrolytes to exploit their improved functionalities. Despite these prospects, the impact of organic cation behavior on interfacial processes remains largely underexplored compared to the widely studied anion behavior. The present study demonstrates that the weakened interactions between cations and anions engender "unprotected" organic cations in highly Li-concentrated ionic liquid electrolytes, leading to the decomposition of electrolytes during the initial charge. This decomposition behavior is manifested by the substantial irreversible capacities and inferior initial Coulombic efficiencies observed during the initial charging of graphite negative electrodes, resulting in considerable electrolyte consumption and diminished energy densities in full-cell configurations. The innate cation behavior is ascertained by examining the coordination environment of ionic liquid electrolytes with varied Li concentrations, where intricate ionic interactions between organic cations and anions are unveiled. In addition, anionic species with high Lewis basicity were introduced to reinforce the ionic interactions involving organic cations and improve the initial Coulombic efficiency. This study verifies the role of unprotected organic cations while highlighting the significance of the coordination environment in the performance of ionic liquid electrolytes.

Fluoride Ion in Alcohols: Isopropanol vs Hexafluoroisopropanol.

The utility of alcohol as a hydrogen bonding donor is considered a providential avenue for moderating the high basicity and reactivity of the fluoride ion, typically used with large cations. However, the practicality of alcohol-fluoride systems in reactions is hampered by the limited understanding of the pertinent interactions between the OH group and F-. Therefore, this study comparatively investigates the thermal, structural, and physical properties of the CsF-2-propanol and CsF-1,1,1,3,3,3-hexafluoro-2-propanol systems to explicate the effects of the fluoroalkyl group on the interaction of alcohols and F-. The two systems exhibit vastly different phase diagrams despite the similar saturated concentrations. A combination of spectroscopic analyses, alcohol activity coefficient measurements, and theoretical calculations reveal the fluorinated alcohol system harbors the stronger OH···F- interactions between the two systems. The diffusion coefficient and ionic conductivity measurements attribute the present results to disparate states of ion association in the two systems.

Trigger of the Highly Resistive Layer Formation at the Cathode-Electrolyte Interface in All-Solid-State Lithium Batteries Using a Garnet-Type Lithium-Ion Conductor.

Interfacial materials design is critical in the development of all-solid-state lithium batteries. We must develop an electrode-electrolyte interface with low resistance and effectively utilize the energy stored in the battery system. Here, we investigated the highly resistive layer formation process at the interface of a layered cathode: LiCoO2, and a garnet-type solid-state electrolyte: Li6.4La3Zr1.4Ta0.6O12, during the cosintering process using in situ/ex situ high-temperature X-ray diffraction. The onset temperature of the reaction between a lithium-deficient LixCoO2 and Li6.4La3Zr1.4Ta0.6O12 is 60 °C, while a stoichiometric LiCoO2 does not show any reaction up to 900 °C. The chemical potential gap of lithium first triggers the lithium migration from the garnet phase to the LixCoO2 below 200 °C. The lithium-extracted garnet gradually decomposes around 200 °C and mostly disappears at 500 °C. Since the interdiffusion of the transition metal is not observed below 500 °C, the early-stage reaction product is the decomposed lithium-deficient garnet phase. Electrochemical impedance spectroscopy results showed that the highly resistive layer is formed even below 200 °C. The present work offers that the origin of the highly resistive layer formation is triggered by lithium migration at the solid-solid interface and decomposition of the lithium-deficient garnet phase. We must prevent spontaneous lithium migration at the cathode-electrolyte interface to avoid a highly resistive layer formation. Our results show that the lithium chemical potential gap should be the critical parameter for designing an ideal solid-solid interface for all-solid-state battery applications.

Systematic Study of Aluminum Corrosion in Ionic Liquid Electrolytes for Sodium-Ion Batteries: Impact of Temperature and Concentration.

The development of sodium-ion batteries utilizing sulfonylamide-based electrolytes is significantly encumbered by the corrosion of the Al current collector, resulting in capacity loss and poor cycling stability. While ionic liquid electrolytes have been reported to suppress Al corrosion, a recent study found that pitting corrosion occurs even when ionic liquids are employed. This study investigates the effects of temperature and Na salt concentration on the Al corrosion behavior in different sulfonylamide-based ionic liquid electrolytes for sodium-ion batteries. In the present work, cyclic voltammetry measurements and scanning electron microscopy showed that severe Al corrosion occurred in ionic liquids at high temperatures and low salt concentrations. X-ray photoelectron spectroscopy was employed to identify the different elemental components and verify the thickness of the passivation layer formed under varied salt concentrations and temperatures. The differences in the corrosion behaviors observed under the various conditions are ascribed to the ratio of free [FSA]- to Na+-coordinating [FSA]- in the electrolyte and the stability of the newly formed passivation layer. This work aims at augmenting the understanding of Al corrosion behavior in ionic liquid electrolytes to develop advanced batteries.

Mechanism of Reductive Fluorination by PTFE-Decomposition Fluorocarbon Gases for WO3.

Reductive fluorination, which entails the substitution of O2- from oxide compounds with F- from fluoropolymers, is considered a practical approach for preparing transition-metal oxyfluorides. However, the current understanding of the fundamental reaction paths remains limited due to the analytical complexities posed by high-temperature reactions in glassware. Therefore, to expand this knowledgebase, this study investigates the reaction mechanisms behind the reductive fluorination of WO3 using polytetrafluoroethylene (PTFE) in an Ni reactor. Here, we explore varied reaction conditions (temperature, duration, and F/W ratio) to suppress the formation of carbon byproducts, minimize the dissipation of fluorine-containing tungsten (VI) compounds, and achieve a high fluorine content. The gas-solid reaction paths are analyzed using infrared spectroscopy, which revealed tetrafluoroethylene (C2F4), hexafluoropropene (C3F6), and iso-octafluoroisobutene (i-C4F8) to be the reactive components in the PTFE-decomposition gas during the reactions with WO3 at 500 °C. CO2 and CO are further identified as gaseous byproducts of the reaction evincing that the reaction is prompted by difluorocarbene (:CF2) formed after the cleavage of C═C bonds in i-C4F8, C3F6, and C2F4 upon contact with the WO3 surface. The solid-solid reaction path is established through a reaction between WO3 and WO3-xFx where solid-state diffusion of O2- and F- is discerned at 500 °C.

In Situ Orthorhombic to Amorphous Phase Transition of Nb2O5 and Its Temperature Effect on Pseudocapacitive Behavior.

Niobium pentoxide (Nb2O5) represents an exquisite class of negative electrode materials with unique pseudocapacitive kinetics that engender superior power and energy densities for advanced electrical energy storage devices. Practical energy devices are expected to maintain stable performance under real-world conditions such as temperature fluctuations. However, the intercalation pseudocapacitive behavior of Nb2O5 at elevated temperatures remains unexplored because of the scarcity of suitable electrolytes. Thus, in this study, we investigate the effect of temperature on the pseudocapacitive behavior of submicron-sized Nb2O5 in a wide potential window of 0.01-2.3 V. Furthermore, ex situ X-ray diffraction and X-ray photoelectron spectroscopy reveal the amorphization of Nb2O5 accompanied by the formation of NbO via a conversion reaction during the initial cycle. Subsequent cycles yield enhanced performance attributed to a series of reversible NbV, IV/NbIII redox reactions in the amorphous LixNb2O5 phase. Through cyclic voltammetry and symmetric cell electrochemical impedance spectroscopy, temperature elevation is noted to increase the pseudocapacitive contribution of the Nb2O5 electrode, resulting in a high rate capability of 131 mAh g-1 at 20,000 mA g-1 at 90 °C. The electrode further exhibits long-term cycling over 2000 cycles and high Coulombic efficiency ascribed to the formation of a robust, [FSA]--originated solid-electrolyte interphase during cycling.

Octaphyrin(1.0.1.0.1.0.1.0) as an Organic Electrode for Li and Na Rechargeable Batteries.

Organic electrode materials for rechargeable batteries have come into the spotlight due to their structural tunability and diversity. In this study, it is found that bisnickel(II) meso-mesityloctaphyrin(1.0.1.0.1.0.1.0) (Oct) is exhibiting multiple oxidation states with extended π-conjugation pathways to afford an active electrode material in Li and Na-organic batteries and secure interactions with Li+ (or Na+ ) and anions enabling efficient dual ionic charge/discharge behaviors. Cyclic voltammograms of the Oct electrode elucidate constantly reversible redox processes in both Li and Na organic batteries and pseudocapacitive behaviors at high currents. Subsequent absorption transformations in CV-UV/VIS/NIR spectroscopic analysis and TD-DFT calculations upon the different redox states of Oct conclusively indicate that six electrons are involved in redox-interconversions per unit cycle with corresponding absorption transformations, which also assessed with charge-and-discharge cell capacities. Significant contributions of the pseudocapacitive processes over the diffusion-controlled processes proceeding in Li- and Na-Oct cells induced fast charge/discharge performance and long-term cyclability.

Strategies for Harnessing High Rate and Cycle Performance from Graphite Electrodes in Potassium-Ion Batteries.

Potassium-ion batteries (PIBs) have been lauded as the next-generation energy storage systems on account of their high voltage capabilities and low costs and the high abundance of potassium resources. However, the practical utility of PIBs has been heavily encumbered by severe K metal dendrite formation, safety issues, and insufficient electrochemical performance during operations─indeed critical issues that underpin the need for functional electrolytes with high thermal stability, robust solid-electrolyte interphase (SEI)-forming capabilities, and high electrochemical performance. In a bid to establish a knowledge framework for harnessing high rate capabilities and long cycle life from graphite negative electrodes, this study presents the physical properties and electrochemical behavior of a high K+ concentration inorganic ionic liquid (IL) electrolyte, K[FSA]-Cs[FSA] (FSA- = bis(fluorosulfonyl)amide) (54:46 in mol), at an intermediate temperature of 70 °C. This IL electrolyte demonstrates an ionic conductivity of 2.54 mS cm-1 and a wide electrochemical window of 5.82 V. Charge-discharge tests performed on a graphite negative electrode manifest a high discharge capacity of 278 mAh g-1 (0.5 C) at 70 °C, a high rate capability (106 mAh g-1 at 100 C), and a long cyclability (98.7% after 450 cycles). Stable interfacial properties observed by electrochemical impedance spectroscopy during cycling are attributed to the formation of sulfide-rich all-inorganic SEI, which was examined through X-ray photoelectron spectroscopy. The performance of the IL is collated with that of an N-methyl-N-propylpyrrolidinium-based organic IL to provide insight into the synergism between the highly concentrated K+ electrolyte at intermediate temperatures and the all-inorganic SEI during electrochemical operations of the graphite negative electrode.

Mixed alkali-ion transport and storage in atomic-disordered honeycomb layered NaKNi2TeO6.

Honeycomb layered oxides constitute an emerging class of materials that show interesting physicochemical and electrochemical properties. However, the development of these materials is still limited. Here, we report the combined use of alkali atoms (Na and K) to produce a mixed-alkali honeycomb layered oxide material, namely, NaKNi2TeO6. Via transmission electron microscopy measurements, we reveal the local atomic structural disorders characterised by aperiodic stacking and incoherency in the alternating arrangement of Na and K atoms. We also investigate the possibility of mixed electrochemical transport and storage of Na+ and K+ ions in NaKNi2TeO6. In particular, we report an average discharge cell voltage of about 4 V and a specific capacity of around 80 mAh g-1 at low specific currents (i.e., < 10 mA g-1) when a NaKNi2TeO6-based positive electrode is combined with a room-temperature NaK liquid alloy negative electrode using an ionic liquid-based electrolyte solution. These results represent a step towards the use of tailored cathode active materials for "dendrite-free" electrochemical energy storage systems exploiting room-temperature liquid alkali metal alloy materials.

Stable Cycle Performance of a Phosphorus Negative Electrode in Lithium-Ion Batteries Derived from Ionic Liquid Electrolytes.

Although high-capacity negative electrode materials are seen as a propitious strategy for improving the performance of lithium-ion batteries (LIBs), their advancement is curbed by issues such as pulverization during the charge/discharge process and the formation of an unstable solid electrolyte interphase (SEI). In particular, electrolytes play a vital role in determining the properties of an SEI layer. Thus, in this study, we investigate the performance of a red phosphorus/acetylene black composite (P/AB) prepared by high-energy ball milling as a negative electrode material for LIBs using organic and ionic liquid (IL) electrolytes. Galvanostatic tests performed on half cells demonstrate high discharge capacities in the 1386-1700 mAh (g-P/AB)-1 range along with high Coulombic efficiencies of 85.3-88.2% in the first cycle, irrespective of the electrolyte used. Upon cycling, the Li[FSA]-[C2C1im][FSA] (FSA- = bis(fluorosulfonyl)amide and C2C1im+ = 1-ethyl-3-methylimidazolium) IL electrolyte (2:8 in mol) demonstrates a high capacity retention of 78.8% after 350 cycles, whereas significant capacity fading is observed in the Li[PF6] and Li[FSA] organic electrolytes. Electrochemical impedance spectroscopy conducted with cycling revealed lower interfacial resistance in the IL electrolyte than in the organic electrolytes. Scanning electron microscopy and X-ray photoelectron spectroscopy after cycling in different electrolytes evinced that the IL electrolyte facilitates the formation of a robust SEI layer comprising multiple layers of sulfur species resulting from FSA- decomposition. A P/AB|LiFePO4 full cell using the IL electrolyte showed superior capacity retention than organic electrolytes and a high energy density under ambient conditions. This work not only illuminates the improved performance of a phosphorous-based negative electrode alongside ionic liquid electrolytes but also displays a viable strategy for the development of high-performance LIBs, especially for large-scale applications.

Improvement of Electrochemical Stability Using the Eutectic Composition of a Ternary Molten Salt System for Highly Concentrated Electrolytes for Na-Ion Batteries.

The increase in the concentration of electrolytes for secondary batteries has significant advantages in terms of physicochemical and electrochemical performance. This study aims to explore a highly concentrated electrolyte for Na-ion batteries using a ternary salt system. The eutectic composition of the Na[N(SO2F)2]-Na[N(SO2F)(SO2CF3)]-Na[SO3CF3] ternary molten salt system increases solubility into an organic solvent, enabling the use of highly concentrated electrolytes for Na-ion batteries. The ternary salt system achieved concentrations of 5.0 m (m = mol kg-1) with propylene carbonate (PC), 2.9 m with dimethoxyethane, 2.0 m with ethylene carbonate/dimethyl carbonate, and 3.9 m with ethylene carbonate/diethyl carbonate. The highly concentrated electrolyte of 5.0 m in PC suppressed Al corrosion and exhibited better oxidative stability. Stable electrochemical performance using hard carbon/NaCrO2 in the full-cell configuration introduces a new strategy to explore highly concentrated electrolytes for secondary batteries.

Generation of Elemental Fluorine through the Electrolysis of Copper Difluoride at Room Temperature.

The safe generation of F2 gas at room temperature by using simple cell configurations has been the "holy grail" of fluorine research for centuries. Thus, to address this issue, we report generation of F2 gas through the electrolysis of CuF2 in a CsF-2.45HF molten salt without the evolution of H2 gas. The CuF2 is selected through a series of thermodynamic and kinetic assessments of possible metal fluorides. Anode assessments on graphite and glass-like carbon demonstrate the effect of the absence of the anode during generation of F2 gas owing to stabilized operations at room temperature. Although the Ni anode dissolves during electrolysis in the conventional medium-temperature cell, herein, it facilitates stable electrolysis over 100 h, achieving an F2 gas purity of over 99 % with the potential to operate using one-compartment electrolysis. This work presents a safe and propitious method for the generation of high-purity F2 gas for small-scale lab and industrial applications.

Transport Properties of Ionic Liquid and Sodium Salt Mixtures for Sodium-Ion Battery Electrolytes from Molecular Dynamics Simulation with a Self-Consistent Atomic Charge Determination.

Ionic liquid (IL) has been considered as a potential electrolyte for developing next-generation sodium-ion batteries. A highly concentrated ionic system such as IL is characterized by the significant influence of intramolecular polarization and intermolecular charge transfer that vary with the combination of cations and anions in the system. In this work, a self-consistent atomic charge determination using the combination of classical molecular dynamics (MD) simulation and density functional theory (DFT) calculation is employed to investigate the transport properties of three mixtures of ILs with sodium salt relevant to the electrolyte for a sodium-ion battery: [1-ethyl-3-methylimidazolium, Na][bis(fluorosulfonyl)amide] ([C2C1im, Na][FSA]), [N-methyl-N-propylpyrrolidinium, Na][FSA] ([C3C1pyrr, Na][FSA]), and [K, Na][FSA]. The self-consistent method is versatile to address the intramolecular polarization and intermolecular charge transfer in response to the cation-anion combination, as well as the variation in their compositions. The structure and dynamic properties of IL mixtures obtained from the method are in line with those from the experimental works. The comparison to the Nernst-Einstein estimates shows that the electrical conductivity is reduced due to correlated motions among the ions, and the contribution to the conductivity from each ion species is not necessarily ranked in the same order as the diffusion coefficient. It is further seen that the increase of the sodium-ion composition reduces the fluidity of the system. The results highlight the potential of the method and the microscopic description that it can provide to assist the investigation toward a sensible design of IL mixtures as an electrolyte for a high-performance sodium-ion battery.

High-voltage honeycomb layered oxide positive electrodes for rechargeable sodium batteries.

Honeycomb layered oxides from Na2Ni2-xCoxTeO6 family were assessed for use as positive electrodes in rechargeable sodium batteries at ambient and elevated temperatures using ionic liquids. Substitution of nickel with cobalt increases the discharge voltage to nearly 4 V (versus Na+/Na), surpassing the average voltages of most Na based layered oxide positive electrodes.

Potassium Difluorophosphate as an Electrolyte Additive for Potassium-Ion Batteries.

The limited cyclability and inferior Coulombic efficiency of graphite negative electrodes have been major impediments to their practical utilization in potassium-ion batteries (PIBs). Herein, for the first time, potassium difluorophosphate (KDFP) electrolyte additive is demonstrated as a viable solution to these bottlenecks by facilitating the formation of a stable and K+-conducting solid-electrolyte interphase (SEI) on graphite. The addition of 0.2 wt % KDFP to the electrolyte results in significant improvements in the (de)potassiation kinetics, capacity retention (76.8% after 400 cycles with KDFP vs 27.4% after 100 cycles without KDFP), and average Coulombic efficiency (∼99.9% during 400 cycles) of the graphite electrode. Moreover, the KDFP-containing electrolyte also enables durable cycling of the K/K symmetric cell at higher efficiencies and lower interfacial resistance as opposed to the electrolyte without KDFP. X-ray diffraction and Raman spectroscopy analyses have confirmed the reversible formation of a phase-pure stage-1 potassium-graphite intercalation compound (KC8) with the aid of KDFP. The enhanced electrochemical performance by the KDFP addition is discussed based on the analysis of the SEI layer on graphite and K metal electrodes by X-ray photoelectron spectroscopy.

Potassium Single Cation Ionic Liquid Electrolyte for Potassium-Ion Batteries.

Potassium-ion batteries (PIBs) are a promising post-lithium-ion battery (LIB), as their resources are abundant and low-cost and may have a higher voltage than LIBs. However, the high operating voltage and extremely high reactivity of potassium metal require a chemically safe electrolyte with oxidative and reductive stabilities. In this study, a potassium single cation ionic liquid (K-SCIL), which contains only K+ as the cationic species and has a high electrochemical stability, low flammability, and low vapor pressure, is developed as an electrolyte for PIBs. The mixture of potassium bis(fluorosulfonyl)amide and potassium (fluorosulfonyl)(trifluoromethylsulfonyl)amide at a molar ratio of 55:45 had the lowest melting point of 67 °C. The K+ concentration in this K-SCIL is high (8.5 mol dm-3 at 90 °C) due to the absence of solvents and bulky organic cations. In addition, the electrochemical window is as wide as 5.6 V, which enables the construction of PIBs with a high energy density. A high current density can be achieved with this K-SCIL, owing to the absence of a K+ concentration gradient. The electrolyte was successfully used with a graphite negative electrode, enabling the reversible intercalation/deintercalation of K+, as confirmed by X-ray diffraction.

Fluoride Ion Interactions in Alkali-Metal Fluoride-Diol Complexes.

The activity of F- is an important factor in the design of both inorganic and organic reactions involving fluorine compounds. The present study investigates interactions of F- with diols in alkali-metal fluoride-diol complexes. Increases in the reactivities of alkali-metal fluorides and their solubilities in alcohols is observed with increasing cation size. The difference in alkali-metal ion size produces different structural motifs for F--diol complex salts. The CsF complex salt with ethylene glycol (EG), CsF-EG, has a layered structure, whereas the Rb and K complex salts, (RbF)5-(EG)4 and (KF)5-(EG)4, form columnar structures. Comparison of the CsF complex salts with three different diols- EG, 1,3-propylene glycol (PG13), and 1,4-butylene glycol (PG14)-revealed that the diol chain length affects the bridging mode in their layered structures. EG bridges two OH oxygen atoms within the same CsF layer in CsF-EG, whereas PG13 and BG14 bridge two OH oxygen atoms in different CsF layers in (CsF)2-PG13 and CsF-BG14, respectively. The F- ion coordination environment involves interactions between alkali-metal ions and H atom(s) in the diol OH groups, where the F-···H interactions are more dominant than the F-···M+ interaction, based on Hirshfeld surface analyses. The O-H bond weakening observed by infrared spectroscopy also reflects the strengths of the F-···H interactions in these complex salts.

Hydro-nium bis-(tri-fluoro-methane-sulfon-yl)amide-18-crown-6 (1/1).

The structure of the title compound, H3O+·C2F6NO4S2 -·C12H24O6 or [H3O+·C12H24O6][N(SO2CF3)2 -], which is an ionic liquid with a melting point of 341-343 K, has been determined at 113 K. The asymmetric unit consists of two crystallographically independent 18-crown-6 mol-ecules, two hydro-nium ions and two bis-(tri-fluoro-methane-sulfon-yl)amide anions; each 18-crown-6 mol-ecule complexes with a hydro-nium ion. In one 18-crown-6 mol-ecule, a part of the ring exhibits conformational disorder over two sets of sites with an occupancy ratio of 0.533 (13):0.467 (13). One hydro-nium ion is complexed with the ordered 18-crown-6 mol-ecule via O-H⋯O hydrogen bonds with H2OH⋯OC distances of 1.90 (6)-2.19 (7) Å, and the other hydro-nium ion with the disordered crown mol-ecule with distances of 1.85 (6)-2.36 (6) Å. The hydro-nium ions are also linked to the anions via O-H⋯F hydrogen bonds. The crystal studied was found to be a racemic twin with a component ratio of 0.55 (13):0.45 (13).

Deoxofluorination of graphite oxide with sulfur tetrafluoride.

In this study, deoxofluorination of graphite oxide (GO) using sulfur tetrafluoride (SF4) at a temperature below the decomposition temperature of GO (∼200 °C) was investigated for the first time with and without HF catalysis. At 25 °C, the reaction proceeds only at high SF4 pressures (≥8 atm) when not catalyzed by HF and at 1 atm SF4 under the catalysis of HF. The degree of fluorination increases at higher temperatures and SF4 pressures. Hydroxy and carbonyl groups are replaced by fluorine following this reaction, and SF4 and SOF2 are introduced into the product, while the epoxy groups do not react. SF4 and SOF2 in the products are removed by washing with water. The obtained product is less hygroscopic than pristine GO owing to the hydrophobicity of the fluorine atom. The interlayer separation of the product is increased after deoxofluorination despite the smaller size of fluorine than the sizes of the oxygen-containing functional groups. When compared with direct fluorination using elemental fluorine, deoxofluorination using SF4 has the advantages of high reactivity with hydroxy groups and the preservation of the carbon skeleton, and the reaction results in the formation of graphite oxyfluoride.

Sodium Ion Batteries using Ionic Liquids as Electrolytes.

Sodium ion batteries have been developed using ionic liquids as electrolytes. Sodium is superior to lithium as a raw material for mass production of large-scale batteries for energy storage due to its abundance and even distribution across the earth. Ionic liquids are non-volatile and non-flammable, which improved the safety of the batteries remarkably. In addition, operation temperatures were extended to higher values, improving the performance of the batteries by facilitating the reaction at the electrode and mass transfer. Binary systems of sodium and quaternary ammonium salts, such as 1-ethyl-3-methylimidazolium and N-methyl-N-propylpyrrolidinium bis(fluorosulfonyl)amide, were employed as electrolytes for sodium ion batteries. A series of positive and negative electrode materials were examined to be combined with these ionic liquid electrolytes. A 27 Ah full cell was fabricated employing sodium chromite (NaCrO2 ) and hard carbon as positive and negative electrode materials, respectively. The gravimetric energy density obtained for the battery was 75 Wh kg-1 and its volumetric energy density was 125 Wh L-1 . The capacity retention after 500 cycles was 87 %. Further improvement of the cell performance and energy density is expected on development of suitable electrode materials and optimization of the cell design.