Inorganic Ionic Liquids Research Articles

Pyrophosphate Na2FeP2O7 as a low-cost and high-performance positive electrode material for sodium secondary batteries utilizing an inorganic ionic liquid

The electrochemical performance of a Na2FeP2O7 positive electrode has been evaluated in an inorganic ionic liquid NaFSA–KFSA (FSA = bis(fluorosulfonyl)amide) at 363 K. The electrode delivers a reversible capacity of 91 mAh g−1 with excellent rate capability (59 mAh g−1 at 2000 mA g−1) and a capacity retention of 91% over 1000 cycles, which facilitates the development of low-cost and high-safety sodium secondary batteries for large-scale energy storage applications. The average oxidation state of iron increases upon sodium extraction, as evidenced by the edge shift of an X-ray absorption spectroscopy analysis. According to an extended X-ray absorption fine structure analysis, the sodium extraction is accompanied by a shortening of Fe–O bonds.

Electrochemical and structural investigation of NaCrO2 as a positive electrode for sodium secondary battery using inorganic ionic liquid NaFSA–KFSA

The electrochemical performance of NaCrO2 as a positive electrode material for an intermediate-temperature sodium secondary battery was evaluated in an inorganic ionic liquid, NaFSA–KFSA (FSA = bis(fluorosulfonyl)amide), at 363 K. The positive electrode using NaCrO2, acetylene black, and polytetrafluoroethylene exhibited a stable discharge capacity of 113 mA h g−1 at a current density of 125 mA g−1. The Coulombic efficiency and the capacity retention at the 100th cycle were 99.6% and 98.5%, respectively. Even at the very high current density of 2000 mA g−1, the discharge capacity was maintained at 63 mA h g−1. X-ray diffraction analyses revealed that the deintercalation of Na+ ion from NaCrO2 was associated with several phase transitions in the following sequence: rhombohedral O3, monoclinic O′3, and monoclinic P′3.

New Approaches to the Low-melting Inorganic Ionic Liquid Challenge

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A green chemical approach for preparation of PtxCuy nanoparticles with a concave surface in molten salt for methanol and formic acid oxidation reactions

Molten salts are a kind of inorganic ionic liquid, which have advantages of a wide liquid range, negligible vapor pressure, good solubility characteristics, non-flammability, excellent thermal and chemical stability, and more importantly, they are low-cost and recyclable. These advantages have aroused an appealing green chemical approach to synthesize nanoparticles (NPs) with controlled morphologies. In the current research, we synthesized PtxCuy (x/y = 23/77, 51/49, 74/26, 83/17) nanoparticles with a concave and clean surface in the KNO3–LiNO3 molten salt system, in air, without using any organic solvent or capping agent. The as-prepared PtxCuy NPs were characterized by X-ray diffraction (XRD), energy-dispersive X-ray (EDX) spectroscopy, transmission electron microscopy (TEM) and high-resolution TEM (HRTEM). The results indicated that the as-obtained PtxCuy alloy had a face-centered-cubic (fcc) polycrystal structure in which the lattice parameter and composition relationship followed Vegard's law in the Cu-poor regions. The results of CV on methanol and formic acid electrooxidation indicated that Pt74Cu26/C exhibited a remarkable enhancement in catalytic activities compared with the commercially used Pt/C catalyst.

ChemInform Abstract: Chemistry of Polynuclear Transition‐Metal Complexes in Ionic Liquids

AbstractReview: 122 refs.

Tetrahedral order, pair correlation entropy, and waterlike liquid state anomalies: Comparison of GeO2 with BeF2, SiO2, and H2O

Molecular dynamics simulations of the Oeffner-Elliot model of germania (GeO(2)) are performed to identify nested regions of anomalous behavior in structural order, diffusivity, and pair entropy in the density-temperature plane, analogous to that seen in BeF(2), SiO(2), and H(2)O. The decreasing constraint of local tetrahedrality in GeO(2), compared to SiO(2) and BeF(2), substantially lowers the onset temperatures for anomalous behavior relative to the experimental melting temperatures (T(m)). Germania resembles water, more strongly than the ionic melts, in terms of temperatures for onset of anomalous behavior as well as in the order maps; for example, the structural anomaly sets in at 3.42T(m) in BeF(2), 3.09T(m) in SiO(2), 1.43T(m) in GeO(2), and 1.21T(m) in H(2)O. The detailed shapes of the anomalous regimes vary for different systems but the relative temperatures of onset for different anomalies are very similar in the different systems. The pair correlation entropy is shown to be a crucial and experimentally accessible quantity for relating structure, entropy, and diffusivity that could be potentially useful for a large class of inorganic ionic liquids.

Adsorption behavior of Pd (II) using pyridine series ionic liquid and inorganic substrate–ionic liquid composite material

イオン液体を吸着場とする，クリーンなPd(II) 回収プロセスを構築するために，ピリジン系イオン液体を用いてPd(II) 塩素イオン錯体の吸着挙動を検討した。ピリジン系イオン液体へのPd(II) の吸着は，イオン交換樹脂を用いた従来の結果と同様に，低HCl濃度条件において最大吸着を示すことが明らかとなった。しかしながら，PdCl2濃度を 1， 5， 10， 15， 20， 30， 50 (46) mmol⁄dm3 として吸着試験を行ったところ，従来得られるようなLangmuir型の吸着が認められず，Langmuir吸着等温線に適合しない結果が得られた。PdCl2は高HCl濃度溶液中ではPdCl42−として存在していることから溶解性は良好である。しかしながら低HCl濃度溶液中では多角化し溶解性の低下を引き起こす。このような結果は，イオン液体を用いたPd (II)の吸着が化学吸着により支配されることを示し，ピリジンへのPd (II)の直接的な配位が予想される。また，無機担体へイオン液体を含浸したハイブリッド吸着材もPd (II)吸着材としての有用性を示した。

Inorganic Materials and Ionic Liquids: Preparation of Inorganic Materials Using Ionic Liquids (Adv. Mater. 2/2010)

Inorganic Materials and Ionic Liquids: Preparation of Inorganic Materials Using Ionic Liquids (Adv. Mater. 2/2010)

Binary and Ternary Mixtures of MFSA (M = Li, K, Cs) as New Inorganic Ionic Liquids

Thermal properties of alkali bis(fluorosulfonyl)amides, MFSA (M = Li, K, Cs), have been investigated. Binary phase diagrams of LiFSA-KFSA, LiFSA-CsFSA and KFSA-CsFSA systems have been constructed. The eutectic point for the binary systems are 338 K at (<i>x</i>Li, <i>x</i>K) = (0.45, 0.55), 331 K at (<i>x</i>Li, <i>x</i>Cs) = (0.40, 0.60) and 333 K at (<i>x</i>K, <i>x</i>Cs) = (0.60, 0.40). The eutectic point for the ternary LiFSA-KFSA-CsFSA system is 309 K at a nearly equimolar composition. The electrochemical window of the LiFSA-KFSA at 348 K and LiFSA-KFSA-CsFSA at 325 K are as wide as 6.0 V with the cathode limit being lithium metal deposition. These new inorganic ionic liquids are highly promising for various electrochemical applications.

Novel inorganic ionic liquids possessing low melting temperatures and wide electrochemical windows: Binary mixtures of alkali bis(fluorosulfonyl)amides

Thermal properties of alkali bis(fluorosulfonyl)amides, MFSI (M = Li, Na, K, Rb, Cs), have been investigated. Binary phase diagrams of LiFSI–KFSI and NaFSI–KFSI systems have been constructed. Eutectic point for LiFSI–KFSI is 338 K at ( x Li, x K) = (0.45, 0.55) and, that for NaFSI–KFSI is 330 K at ( x Na, x K) = (0.45, 0.55). The electrochemical window of the eutectic LiFSI–KFSI is as wide as 6.0 V at 348 K with the cathode limit being lithium metal deposition. The electrochemical window of the eutectic NaFSI–KFSI is 5.0 V at 340 K with sodium metal deposition at the cathode limit. These new inorganic ionic liquids are highly promising for various electrochemical applications.

Binary Mixtures of MFSI (M = Li, Na, K, Rb, Cs) as New Inorganic Ionic Liquids

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Aromatic Nitration in Liquid Ag0.51K0.42Na0.07NO3

Aromatic molecules have a strong affinity for silver(I) and dissolve to a limited extent in Ag 0.51K 0.42Na 0.07NO 3, a low-melting eutectic mixture of silver, potassium, and sodium nitrates. Aromatic nitration in this inorganic ionic liquid leads to products which arise from nonelectrophilic substitution pathways.

Novel Room Temperature Inorganic Ionic Liquids.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Novel Room Temperature Inorganic Ionic Liquids

AbstractNew inorganic ionic liquids (IIL) consisting of an inorganic polyoxometalate anion with the Keggin structure and a sodium cation, that is Na13[Ln(TiW11O39)2]·xH2O [where Ln = lanthanide (type 1)], Na5[MTiW11O39]·xH2O and Na6[MTiW11O39]·xH2O [where M = transition metal (type 2)], were prepared and their physicochemical properties were investigated. These ionic liquids were characterized by NMR and IR spectroscopy and by elemental analysis. Their melting point, viscosity, conductivity, thermal stability, and miscibility with water and organic solvents were determined. When the temperature is below ambient temperature (about 298 K) these ionic liquids are almost immiscible with water. When the temperature is raised, the solubility of the new ionic liquids increases sharply. The influence of the size and of the charge density of both the cations and anions on these properties was examined. The most remarkable feature of IILs is that water is their indispensable component. The role of the water molecule in ionic liquids is similar to that of crystalline water in hydrated compounds. (© Wiley‐VCH Verlag GmbH &amp; Co. KGaA, 69451 Weinheim, Germany, 2004)