Li+−(Diglyme)2 and LiClO4−Diglyme Complexes:  Barriers to Lithium Ion Migration

Baboul, Anwar G.; Redfern, Paul C.; Sutjianto, A.; Curtiss, Larry A.

doi:10.1021/ja990507d

Cited by 62 publications

(81 citation statements)

References 22 publications

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“…Our analysis comparing various ether-containing moieties is similar to that of Curtiss and co-workers. 52 We observe similarly that smaller strands, in our case down to the DME monomer, offer stronger solvation than a single extended diglyme strand, and the binding energies tend to level off as the coordination number approaches six. Our differences with the use of shorter chains, however, appear to be smaller than those of Curtiss and co-workers, likely due to the addition of the PCM.…”

Section: Comparison Between LI Solvation With Dme and Oligo(ethylesupporting

confidence: 69%

Cluster-continuum quantum mechanical models to guide the choice of anions for Li+-conducting ionomers

Shiau

Liu

Colby

et al. 2013

The Journal of Chemical Physics

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A quantum-mechanical investigation on Li poly(ethylene oxide)-based ionomers was performed in the cluster-continuum solvation model (CCM) that includes specific solvation in the first shell surrounding the cation, all surrounded by a polarizable continuum. A four-state model, including a free Li cation, Li(+)-anion pair, triple ion, and quadrupole was used to represent the states of Li(+) within the ionomer in the CCM. The relative energy of each state was calculated for Li(+) with various anions, with dimethyl ether representing the ether oxygen solvation. The population distribution of Li(+) ions among states was estimated by applying Boltzmann statistics to the CCM energies. Entropy difference estimates are needed for populations to better match the true ionomer system. The total entropy change is considered to consist of four contributions: translational, rotational, electrostatic, and solvent immobilization entropies. The population of ion states is reported as a function of Bjerrum length divided by ion-pair separation with/without entropy considered to investigate the transition between states. Predicted concentrations of Li(+)-conducting states (free Li(+) and positive triple ions) are compared among a series of anions to indicate favorable features for design of an optimal Li(+)-conducting ionomer; the perfluorotetraphenylborate anion maximizes the conducting positive triple ion population among the series of anions considered.

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Section: Comparison Between LI Solvation With Dme and Oligo(ethylesupporting

confidence: 69%

Cluster-continuum quantum mechanical models to guide the choice of anions for Li+-conducting ionomers

Shiau

Liu

Colby

et al. 2013

The Journal of Chemical Physics

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“…PEO chains are known to be soluble in many polar solvents and have strong coordination with Li + . [ 24 ] Therefore, the facilitated dissolving process and consequent higher solubility of ANL-10 in Li salt electrolytes should also be expected.…”

Section: Doi: 101002/aenm201401782mentioning

confidence: 99%

“…In addition, the trend in this non-lithium electrolyte is a little different from those in the LiBF 4 One possible explanation may be that the strong chelation between lithium ions and the oxygen atoms in the PEO chains affect the molecular sizes and behaviors. [ 24 ] Due to the stronger chelation with Li + , long PEO chains could form more folded solvation conformations in Li + containing electrolytes. However, in the non Li + containing electrolyte, since the chelation between the bulky tetrabutylammonium cations and the oxygen atoms are very weak, the solvation conformations of the long PEO chains should be less folded, resulting in the bigger solvation molecular sizes and the lower values of the diffusion coeffi cients.…”

Section: Doi: 101002/aenm201401782mentioning

confidence: 99%

Liquid Catholyte Molecules for Nonaqueous Redox Flow Batteries

Huang

Cheng

Assary

et al. 2014

Advanced Energy Materials

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158

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in aqueous systems due to their limited solubility in water and well distributed redox potentials. [ 2,[13][14][15][16] In contrast, nonaqueous systems can accommodate organic molecules with good solubility and electrochemical compatibility. [ 17 ] Redox active materials are the most important component for nonaqueous redox fl ow batteries (NRFBs), which dictate the overall performance. The desired materials need well separated anodic and cathodic reversible intrinsic redox reactions to accommodate the reversible electron transfer processes of the catholytes and anolytes. Two options can be considered for the material development. First, the same molecular species could be used on both sides of the NRFBs. This kind of molecules, or so-called universal molecules, should have both anodic and cathodic types of reversible redox reactions within one molecular structure so that they can function both as catholyte and anolyte materials. Vanadium ions [18][19][20] and acetylacetonate-based metal complexes [ 21 ] are examples employing this approach. The most obvious advantage is the mitigation of membrane crossover issue, a major issue for capacity decay of fl ow batteries. [ 22 ] However, such universal molecules, especially organic molecules, usually have complex structures, thus leading to high molecular weight, not favorable for the energy and cost considerations. The second option is to use different molecules as catholyte and anolyte materials, respectively. These molecules are single functional molecules, since they have only one type of intrinsic reversible redox reaction (either anodic or cathodic). In this category, since the intrinsic redox reactions can be fully utilized during the charging and discharging processes, higher energy density can be achieved. Single functional molecules usually have simple chemical structures compared to universal ones, which is favorable for the effi cient molecular design and synthesis.One example of the single functional cathlyte molecules is 2,5-di-tert -butyl-1,4-bis(2-methoxyethoxy)benzene (DBBB), as shown in Figure 2 , which is a redox active organic molecule discovered during our recent investigation of the redox shuttles for the lithium ion batteries. [ 15 ] DBBB is built upon the dimethoxydi-tert -butyl-benzene platform and is a very electrochemically reversible (3.9 V vs Li/Li + ), stable and soluble molecule that later found its way to be a promising catholyte candidate in an all organic NRFB. [ 2 ] Redox shuttle molecules, initially proposed for the overcharge protection for lithium ion batteries, have many similar requirements as catholyte molecules, such as good electrochemical reversibility, high redox potential, good solubility, and excellent electrochemical stability. The knowledge of building reversible redox active molecules is precious to the catholyte molecule development, which could serve as the starting point and dramatically shorten the initial exploration Redox fl ow batteries (RFBs) have been increasingly recognized to have signifi cant potentials for ...

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“…On the other hand, the barriers for Li + migration in PEO obtained from quantum-chemical calculations are about 7-11 kcal/ mol for high coordination number [25]. Therefore it is reasonable to expect that the differences of the order of 5-10 kcal/mol or more obtained for the binding energy (Table 2) are relevant and should be reflected in the transport properties.…”

Section: Discussionmentioning

confidence: 98%