Negative Transference Numbers in Poly(ethylene oxide)-Based Electrolytes

Pesko, Danielle M.; Timachova, Ksenia; Bhattacharya, Rajashree; Smith, Mackensie C.; Villaluenga, Irune; Newman, John; Balsara, Nitash P.

doi:10.1149/2.0581711jes

Cited by 188 publications

(387 citation statements)

References 69 publications

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“…Recently, negative Li + ion transference numbers

t_{+, 0}^{}

in poly(ethylene oxide)‐based (PEO‐based) polymer electrolytes have been reported . In this study, the LiTFSI salt concentration in the PEO polymer matrix was varied such that the ratio of Li + ions to ether oxygens,

r = [{L i}^{+}] / [O]

ranges from 0.01 to 0.30.…”

Section: Case Studies Relevant For Energy Storage Technologiesmentioning

confidence: 99%

“…Based on Newman's concentrated solution theory,

t_{+, 0}^{}

was calculated from a set of transport data, namely ionic conductivity

σ_{i o n}

, salt diffusion coefficient

D_{s a l t}

, Li + transference number under anion‐blocking conditions

t_{+, 0}^{a b c}

, and from the thermodynamic factor Φ = d ln a + / d ln c salt . These data were obtained by combining potentiostatic polarization measurements, restricted diffusion measurements and open‐circuit potential measurements of concentration cells . Then, the Equation

true t_{+, 0}^{a b c} = {(() 1 + \frac{2 σ_{i o n} R T {(1 - t_{+, 0}^{e N M R})}^{2} Φ}{c_{s a l t} F^{2} D_{s a l t}})}^{- 1}

…”

Section: Case Studies Relevant For Energy Storage Technologiesmentioning

confidence: 99%

“…A negative

t_{+}^{e N M R}

implies that in the absence of a salt concentration gradient, the cations migrate towards the positive electrode, implying a negative mobility of the cations. The origin can be negatively charged complexes, in which a cation is bound to several anions . It is conceivable that at high ratios

r = [{L i}^{+}] / [O]

, there are not enough oxygen in the polymeric chain for the complexation of all Li + ions.…”

Section: Case Studies Relevant For Energy Storage Technologiesmentioning

confidence: 99%

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Dynamic Ion Correlations in Solid and Liquid Electrolytes: How Do They Affect Charge and Mass Transport?

2019

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Solid and liquid electrolytes for electrochemical energy storage and conversion cells, such as batteries, supercapacitors and fuel cells, contain often high concentrations of mobile ions. Therefore, the ion dynamics in these electrolytes is characterized by pronounced directional correlations between successive ion movements, which exert a strong influence on charge and mass transport. In this manuscript, we review the relevant transport properties of (i) single-ion conducting solid electrolytes and of (ii) liquid electrolytes with a single type of cations and a single type of anions. All transport quantities are based on Onsager's linear irreversible thermodynamics and are defined in the laboratory frame of reference, so that they can be easily related to correlations functions of the equilibrium ion dynamics by means of linear response theory. In the case of single-cation conducting solid electrolytes, we discuss how the complex interplay between cation-cation and cation-lattice interactions leads to a competition between cation self-correlations and distinct-cation correlations. In the case of liquid electrolytes, we describe how cation-cation, anion-anion, and cation-anions correlations influence the various transport quantities, such as total ionic conductivity, Haven ratio, salt diffusion coefficient and cation transference numbers. Moreover, we discuss how, in dilute liquid electrolytes, ion correlations can be governed by ion pair formation. Finally, the competition between cation/ anion and cation/polymer chain interactions can lead to negative cation transference numbers in polymer electrolytes, i. e. to cations migrating towards the positive electrode. Taken together, these case studies showcase how ion correlations in electrolyte systems can strongly influence the overall efficiency of energy storage and conversion devices due to transport limitations.[a] Dr.

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“…Recently, negative Li + ion transference numbers

t_{+, 0}^{}

r = [{L i}^{+}] / [O]

ranges from 0.01 to 0.30.…”

Section: Case Studies Relevant For Energy Storage Technologiesmentioning

confidence: 99%

“…Based on Newman's concentrated solution theory,

t_{+, 0}^{}

was calculated from a set of transport data, namely ionic conductivity

σ_{i o n}

, salt diffusion coefficient

D_{s a l t}

, Li + transference number under anion‐blocking conditions

t_{+, 0}^{a b c}

true t_{+, 0}^{a b c} = {(() 1 + \frac{2 σ_{i o n} R T {(1 - t_{+, 0}^{e N M R})}^{2} Φ}{c_{s a l t} F^{2} D_{s a l t}})}^{- 1}

…”

Section: Case Studies Relevant For Energy Storage Technologiesmentioning

confidence: 99%

“…A negative

t_{+}^{e N M R}

r = [{L i}^{+}] / [O]

, there are not enough oxygen in the polymeric chain for the complexation of all Li + ions.…”

Section: Case Studies Relevant For Energy Storage Technologiesmentioning

confidence: 99%

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Dynamic Ion Correlations in Solid and Liquid Electrolytes: How Do They Affect Charge and Mass Transport?

2019

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“…Steady-state current measurements were performed on lithium symmetric cells using a Biologic VMP3 potentiostat. A more detailed description of this experiment is provided in ref 42. Lithium symmetric cells were prepared by pressing electrolyte into a 508 μm thick silicone spacer and then sandwiching between two lithium electrodes (MTI corporation).…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

Optimizing Ion Transport in Polyether-Based Electrolytes for Lithium Batteries

et al. 2018

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ABSTRACT:We report on the synthesis of poly(diethylene oxidealt-oxymethylene), P(2EO-MO), via cationic ring-opening polymerization of the cyclic ether monomer, 1,3,6-trioxocane. We use a combined experimental and computational approach to study ion transport in electrolytes comprising mixtures of P(2EO-MO) and lithium bis(trifluoromethanesulfonyl) imide (LiTFSI) salt. Mixtures of poly(ethylene oxide) (PEO) and LiTFSI are used as a baseline. The maximum ionic conductivities, σ, of P(2EO-MO) and PEO electrolytes at 90°C are 1.1 × 10 −3 and 1.5 × 10 −3 S/cm, respectively. This difference is attributed to the T g of P(2EO-MO)/ LiTFSI (−12°C), which is significantly higher than that of PEO/LiTFSI (−44°C) at the same salt concentration. Self-diffusion coefficients measured using pulsed-field gradient NMR (PFG-NMR) show that both Li + and TFSI − ions diffuse more rapidly in PEO than in P(2EO-MO). However, the NMR-based cation transference number in P(2EO-MO) (0.36) is approximately twice that in PEO (0.19). The transference number measured by the steady-state current technique, t +,ss , in P(2EO-MO) (0.20) is higher than in PEO (0.08) by a similar factor. We find that the product σt +,ss is greater in P(2-EO-MO) electrolytes; thus, P(2EO-MO) is expected to sustain higher steady-state currents under dc polarization, making it a more efficacious electrolyte for battery applications. Molecular-level insight into the factors that govern ion transport in our electrolytes was obtained using MD simulations. These simulations show that the solvation structures around Li + are similar in both polymers. The same is true for TFSI − . However, the density of Li + solvation sites in P(2EO-MO) is double that in PEO. We posit that this is responsible for the observed differences in the experimentally determined transport properties of P(2EO-MO) and PEO electrolytes.

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“…It is widely known that majority of the currenti sc arried by the anion that results to transferencen umbersl esst han or equal to 0.5, [63,65] in which all the polymer electrolyte components (i.e. [67] Avoidance of these charged clusters by striking ab alance between polymer/salt ratio is therefore critical. [66] An egative transferencen umber is also possible where this manifestation signifies that ion transport occurs through doublets, triplets, or ionic aggregates.…”

Section: Electrochemical Propertiesmentioning

confidence: 99%

Hybrid Solid Polymer Electrolytes with Two‐Dimensional Inorganic Nanofillers

Chua

Fang

Sun

et al. 2018

Chemistry A European J

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Solidp olymer electrolytes are of rapidly increasing importance for the research andd evelopment of future safe batteries with high energy density.T he diversified chemistry and structures of polymers allow the utilization of aw ide range of soft structures for all-polymers olid-state electrolytes. With equal importance is the hybrid solid-state electrolytes consisting of both "soft" polymeric structure and "hard" inorganic nanofillers.T he recent emergence of the re-discovery of many two-dimensional layered materials hass timulated the booming of advanced research in energy storage fields, such as batteries, supercapacitors, and fuel cells. Of special interesti st he mass transport properties of these 2D nanostructures for water,g as, or ions. This review aims at the current progress and prospective development of hybrid polymer-inorganic solid electrolytes based on important 2D materials, including natural clay and synthetic lamellar structures. The ion conduction mechanism and the fabrication, property and device performance of these hybrid solid electrolyteswill be discussed.

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Negative Transference Numbers in Poly(ethylene oxide)-Based Electrolytes

Cited by 188 publications

References 69 publications

Dynamic Ion Correlations in Solid and Liquid Electrolytes: How Do They Affect Charge and Mass Transport?

Dynamic Ion Correlations in Solid and Liquid Electrolytes: How Do They Affect Charge and Mass Transport?

Optimizing Ion Transport in Polyether-Based Electrolytes for Lithium Batteries

Hybrid Solid Polymer Electrolytes with Two‐Dimensional Inorganic Nanofillers

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