Chasing Aqueous Biphasic Systems from Simple Salts by Exploring the LiTFSI/LiCl/H<sub>2</sub>O Phase Diagram

Dubouis, Nicolas; Park, Chanbum; Deschamps, Michaël; Abdelghani-Idrissi, Soufiane; Kanduč, Matej; Colin, Annie; Salanne, Mathieu; Dzubiella, Joachim; Grimaud, Alexis; Rotenberg, Benjamin

doi:10.1021/acscentsci.8b00955

Cited by 39 publications

(54 citation statements)

References 20 publications

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“…This indicates more water molecules are bonded to the ions. [40] The reduced hydrogen bonding in ZL-PAAm is further supported by the decrease in storage modulus ( Figure S5, Supporting Information). Furthermore, the OH − produced by the highly hydrated SO 4 2− will interact with H + , thus increasing the relative ratio between H + and OH − and leading to a decrease of the pH value.…”

Section: Resultsmentioning

confidence: 82%

“…Moreover, the increase in full width at half-maximum (FWHM) further confirms the reduction of the regularity NH 2 groups ( Figure S4b, Supporting Information), which is ascribed to the circumstance that Li + functions as a "pseudoprotonic acid" dopant that can displace interchain hydrogen bonding. [40] The reduced hydrogen bonding in ZL-PAAm is further supported by the decrease in storage modulus ( Figure S5, Supporting Information). Characteristic peaks of C-C skeletal stretching (middle panel) for three hydrogels all locate at 1105 cm −1 , further confirming the main structure of PAAm is not altered by hydrated ions.…”

Section: Resultsmentioning

confidence: 82%

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Antifreezing Hydrogel with High Zinc Reversibility for Flexible and Durable Aqueous Batteries by Cooperative Hydrated Cations

Zhu

Wang

Hong-mei

et al. 2019

Adv Funct Materials

226

167

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Hydrogels are widely used in flexible aqueous batteries due to their liquid-like ion transportation abilities and solid-like mechanical properties. Their potential applications in flexible and wearable electronics introduce a fundamental challenge: how to lower the freezing point of hydrogels to preserve these merits without sacrificing hydrogels' basic advantages in low cost and high safety. Moreover, zinc as an ideal anode in aqueous batteries suffers from low reversibility because of the formation of insulative byproducts, which is mainly caused by hydrogen evolution via extensive hydration of zinc ions. This, in principle, requires the suppression of hydration, which induces an undesirable increase in the freezing point of hydrogels. Here, it is demonstrated that cooperatively hydrated cations, zinc and lithium ions in hydrogels, are very effective in addressing the above challenges. This simple but unique hydrogel not only enables a 98% capacity retention upon cooling down to −20 °C from room temperature but also allows a near 100% capacity retention with >99.5% Coulombic efficiency over 500 cycles at −20 °C. In addition, the strengthened mechanical properties of the hydrogel under subzero temperatures result in excellent durability under various harsh deformations after the freezing process.

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Section: Resultsmentioning

confidence: 82%

Section: Resultsmentioning

confidence: 82%

Antifreezing Hydrogel with High Zinc Reversibility for Flexible and Durable Aqueous Batteries by Cooperative Hydrated Cations

Zhu

Wang

Hong-mei

et al. 2019

Adv Funct Materials

226

167

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“…Such systems are potentially of interest for, e.g., recycling applications or membrane‐free flow batteries. [ 59,60 ]…”

Section: Resultsmentioning

confidence: 99%

Anion Selection Criteria for Water‐in‐Salt Electrolytes

Reber

Grissa

Becker

et al. 2020

Advanced Energy Materials

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Water‐in‐salt electrolytes have enabled the development of novel high‐voltage aqueous lithium‐ion batteries. This study explores the reasons why analogous sodium electrolytes have struggled to reach the same level of electrochemical stability. Solution structure and electrochemical stability are compared for 11 sodium salts, selected among the major classes of salts proposed for highly concentrated electrolytes. The water environment established for each anion is related to its position in the Hofmeister series and a surprisingly strong correlation between the chaotropicity of the anion and the resulting electrochemical stability of the electrolyte is found. The search for suitable sodium salts is complicated by the fact that higher salt concentrations are needed than for their lithium equivalents. Reaching such a high concentration of >25 mol kg−1 with one or a combination of multiple sodium salts that have the desired properties remains a major challenge. Hence, alternative approaches such as multisolvent systems should be explored. The water solubility of NaTFSI can be increased from 8 to 30 mol kg−1 in the presence of ionic liquids. Such a ternary electrolyte enables stable cycling of a 2 V class sodium‐ion battery based on the NaTi2(PO4)3/Na2Mn[Fe(CN)6] electrode couple for 300 cycles at 1C with a Coulombic efficiency of >99.5%.

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“…With regard to the electrolyte structures, we suggested that a large size asymmetry between the anions could trigger the formation of aqueous biphasic systems because of packing constraints at the molecular scale. 49 From this, a simple question emerges: how can we define the size of an ion into these solutions and how can it be captured? Moreover, it has been demonstrated that the anion size also modifies the nanostructuration of the electrolytes.…”

Section: Perspectivesmentioning

confidence: 99%

Confining Water in Ionic and Organic Solvents to Tune Its Adsorption and Reactivity at Electrified Interfaces

et al. 2021

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Conspectus The recent discovery of “water-in-salt” electrolytes has spurred a rebirth of research on aqueous batteries. Most of the attention has been focused on the formulation of salts enabling the electrochemical window to be expanded as much as possible, well beyond the 1.23 V allowed by thermodynamics in water. This approach has led to critical successes, with devices operating at voltages of up to 4 V. These efforts were accompanied by fundamental studies aiming at understanding water speciation and its link with the bulk and interfacial properties of water-in-salt electrolytes. This speciation was found to differ markedly from that in conventional aqueous solutions since most water molecules are involved in the solvation of the cationic species (in general Li + ) and thus cannot form their usual hydrogen-bonding network. Instead, it is the anions that tend to self-aggregate in nanodomains and dictate the interfacial and transport properties of the electrolyte. This particular speciation drastically alters the presence and reactivity of the water molecules at electrified interfaces, which enlarges the electrochemical windows of these aqueous electrolytes. Thanks to this fundamental understanding, a second very active lead was recently followed, which consists of using a scarce amount of water in nonaqueous electrolytes in order to control the interfacial properties. Following this path, it was proposed to use an organic solvent such as acetonitrile as a confinement matrix for water. Tuning the salt/water ratio in such systems leads to a whole family of systems that can be used to determine the reactivity of water and control the potential at which the hydrogen evolution reaction occurs. Put together, all of these efforts allow a shift of our view of the water molecule from a passive solvent to a reactant involved in many distinct fields ranging from electrochemical energy storage to (electro)catalysis. Combining spectroscopic and electrochemical techniques with molecular dynamics simulations, we have observed very interesting chemical phenomena such as immiscibility between two aqueous phases, specific adsorption properties of water molecules that strongly affect their reactivity, and complex diffusive mechanisms due to the formation of anionic and aqueous nanodomains.

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Chasing Aqueous Biphasic Systems from Simple Salts by Exploring the LiTFSI/LiCl/H₂O Phase Diagram

Cited by 39 publications

References 20 publications

Antifreezing Hydrogel with High Zinc Reversibility for Flexible and Durable Aqueous Batteries by Cooperative Hydrated Cations

Antifreezing Hydrogel with High Zinc Reversibility for Flexible and Durable Aqueous Batteries by Cooperative Hydrated Cations

Anion Selection Criteria for Water‐in‐Salt Electrolytes

Confining Water in Ionic and Organic Solvents to Tune Its Adsorption and Reactivity at Electrified Interfaces

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Chasing Aqueous Biphasic Systems from Simple Salts by Exploring the LiTFSI/LiCl/H2O Phase Diagram

Cited by 39 publications

References 20 publications

Antifreezing Hydrogel with High Zinc Reversibility for Flexible and Durable Aqueous Batteries by Cooperative Hydrated Cations

Antifreezing Hydrogel with High Zinc Reversibility for Flexible and Durable Aqueous Batteries by Cooperative Hydrated Cations

Anion Selection Criteria for Water‐in‐Salt Electrolytes

Confining Water in Ionic and Organic Solvents to Tune Its Adsorption and Reactivity at Electrified Interfaces

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Product

Resources

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Chasing Aqueous Biphasic Systems from Simple Salts by Exploring the LiTFSI/LiCl/H₂O Phase Diagram