A new type of "task specific ionic liquid", tetrabutylphosphonium amino acid [P(C4)4][AA], was synthesized by the reaction of tetrabutylphosphonium hydroxide [P(C4)4][OH] with amino acids, including glycine, L-alanine, L-beta-alanine, L-serine, and L-lysine. The liquids produced were characterized by NMR, IR spectroscopies, and elemental analysis, and their thermal decomposition temperature, glass transition temperature, electrical conductivity, density, and viscosity were recorded in detail. The [P(C4)4][AA] supported on porous silica gel effected fast and reversible CO2 absorption when compared with bubbling CO2 into the bulk of the ionic liquid. No changes in absorption capacity and kinetics were found after four cycles of absorption/desorption. The CO2 absorption capacity at equilibrium was 50 mol % of the ionic liquids. In the presence of water (1 wt %), the ionic liquids could absorb equimolar amounts of CO2. The CO2 absorption mechanisms of the ionic liquids with and without water were different.

Ionic liquids (ILs) offer a wide range of promising applications because of their much enhanced properties. However, further development of such materials depends on the fundamental understanding of their hierarchical structures and behaviors, which requires multiscale strategies to provide coupling among various length scales. In this review, we first introduce the structures and properties of these typical ILs. Then, we introduce the multiscale modeling methods that have been applied to the ILs, covering from molecular scale (QM/MM), to mesoscale (CG, DPD), to macroscale (CFD for unit scale and thermodynamics COSMO-RS model and environmental assessment GD method for process scale). In the following section, we discuss in some detail their applications to the four scales of ILs, including molecular scale structures, mesoscale aggregates and dynamics, and unit scale reactor design and process design and optimization of typical IL applications. Finally, we address the concluding remarks of multiscale strategies in the understanding and predictive capabilities of ILs. The present review aims to summarize the recent advances in the fundamental and application understanding of ILs.

It is critically important to understand the structural properties of ionic liquids. In this work, the structures of cations, anions, and cation-anion ion-pairs of 1,3-dialkylimidazolium based ionic liquids were optimized systematically at the B3LYP/6-31+G level of DFT theory, and their most stable geometries were obtained. It was found that there exist only one-hydrogen-bonded ion-pairs in single-atomic anion ionic liquids such as [emim]Cl and [emim]Br, while one- and two-hydrogen-bonded ion-pairs in multiple atomic anion ionic liquids such as [emim]BF(4) and [emim]PF(6) exist. Further studies showed that the cations and anions connect each other to form a hydrogen-bonded network in 1,3-dialkylimidazolium halides, which has been proven by experimental measurement. Furthermore, the correlation of melting points and the interaction energies was discussed for both the single atomic anion and multiple atomic anion ionic liquids.

increased and the energy transform efficiency decreased. For the SPEs in which the Li + are transport by moieties on the polymer chain, their ionic conductivity and electrochemical stability is restricted by the polymer structure, typically, polyethylene oxide (PEO) based SPEs only working in high temperature above 60 °C and at low voltage of below 4.0 V.Ceramic/polymer hybrid solid electrolyte (HSE) is a promising material by combining the advantages of both types of electrolytes, typical HSEs are composed of polymers to enhance the electrode/ electrolyte interfacial compatibility and inorganic fillers to adjust the ionic transportability. [8][9][10][11][12][13][14][15][16][17][18] The fillers could be metal oxides, such as Al 2 O 3 , [10] SiO 2 , [11,12] TiO 2 , [13] and Fe 2 O 3 [14] or fast Li + conductors, such as Li 1.3 Al 0.3 Ti 1.7 (PO 4 ) 3 (LATP), [15] LLZO, [16,17] and LGPS, [18] the materials can not only reduce the polymer matrix crystallinity, but also provide extra diffusion routes for Li + , thus enhance the overall performance of the electrolyte. Mechanical mixing is the most common method to obtain the HSE, and it is convenient and cost-effective. However, the composite electrolyte obtained by this method often shows poor uniformity and the fillers are fail to form interconnected Li + conduct channels, on which ionic conductivity of the composites cannot be enhanced effectively. [11] The other issue bring about by mechanical mixing is the organic/inorganic electrolyte interfacial compatibility, as ions inclined to flow along the low resistance pathways, [6,19] local difference in conductivity may lead to strong space charge layer at the interphase and cause polymer oxidation. Many methods were attempted to optimize this interphase compatibility such as reducing particle size of ceramic, [20,21] making the ceramic fillers orderly, and higher dimension. [22,23] But such problem still exists and the interfacial compatibility cannot be neglected. Making chemical bond is a new strategy to resolve the issue of interface. [24][25][26] Nan's group utilized the catalysis of La in dehydrofluorination and prepared poly(vinylidenefluoride) (PVDF)-Li 6.75 La 3 Zr 1.75 Ta 0.25 O 12 (LLZTO) HSE whose ionic conductivity is as high as 5 × 10 −4 S cm −1 at 25 °C. [26] But this strategy can only be applied to those polymers consisting of H and F in neighbor carbon atoms such as PVDF or poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) [24] which cannot contribute to ionic transport. Archer's group proposed a more universal method by preparing a kind of soft colloidal glasses HSE that PEO chains were covalently grafted onto silica nanoparticles. The HSE works stable in high-voltage nickel cobalt manganese Ceramic/polymer hybrid solid electrolytes (HSEs) have attracted worldwide attentions because they can overcome defects by combining the advantages of ceramic electrolytes (CEs) and solid polymer electrolytes (SPEs). However, the interface compatibility of CEs and SPEs in HSE limits their full function to...

Ionic liquids (ILs) have attracted intensive attention in academia and industry due to their unique properties and potential applications. Nowadays, much interest is focused on finding out what is the main force that determines the properties of ionic liquids. Intuitively like NaCl, in high-temperature molten salt (HTMS) the electrostatic Coulomb force is regarded as the dominant factor that determines the behaviors of ILs. However, a large amount of evidence indicates that such a molten-salt-based simplified explanation is not consistent with the corresponding experimental results. Besides the Coulomb force, the hydrogen bond is another important noncovalent interaction in the IL and is closely related to some important properties and applications, as suggested in some new research results. Therefore in this review, we present results concerning the hydrogen bond in ILs, from the perspective of experiment and calculation, to shed light on its effects and roles. The deep insights into structure, in particular the hydrogen bonds, can provide us with a rational design for the new ILs to fulfill the demands in some complicated chemical processes.