Design strategies and research progress for Water-in-Salt electrolytes

Xiao, Di; Zhang, Li; Li, Zhiwei; Dou, Hui; Zhang, Xiaogang

doi:10.1016/j.ensm.2021.09.035

Cited by 42 publications

(40 citation statements)

References 196 publications

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“…Thus, the sudden increase in the cell voltage at concentrations above 5 mol kg −1 can be mainly attributed to the rapid decrease in the amount of water aggregates. The breakdown of the percolating water H‐bonding network, and the simultaneous formation of small‐sized water aggregates, lead to strong interactions between the water molecules and the ions 23 . This, in turn, facilitates the enhancement in the O‐H bond strength in the individual water molecules, thereby leading to the suppression of the HER and the increase in the cell voltage of the NaClO 4 ‐based supercapacitors 37,56 …”

Section: Resultsmentioning

confidence: 99%

“…The breakdown of the percolating water Hbonding network, and the simultaneous formation of small-sized water aggregates, lead to strong interactions between the water molecules and the ions. 23 This, in turn, facilitates the enhancement in the O-H bond strength in the individual water molecules, thereby leading to the suppression of the HER and the increase in the cell voltage of the NaClO 4 -based supercapacitors. 37,56 The frequency response analysis in Figure 8 demonstrates that the maximum response speed of each supercapacitor is strongly correlated with the above-mentioned transition in the electrolytic structure at the critical salt concentration of 5-6 mol kg À1 .…”

Section: Resultsmentioning

confidence: 99%

“…(A) The normalized size ratios of the water (blue) and ion aggregates (red) in the NaClO 4 electrolytes calculated using the aggregate size ratios obtained by Cho et al 23 (B) The correlation between the cell voltages of the supercapacitors and the breakdown of percolating water H‐bonding networks expressed as 1–< N aggregate > /N total at various concentrations…”

Section: Resultsmentioning

confidence: 99%

“…[19][20][21] In contrast to the conventional aqueous electrolytes, the highly concentrated aqueous electrolytes known as water-in-salt electrolytes (WiSEs) have demonstrated a remarkable extension of the ESW. [22][23][24][25][26][27] The first reported WiSE electrolyte using 21 mol kg À1 LiTFSI exhibited a wide ESW in Li-ion batteries owing to the enhanced Li + and TFSI À interactions and the decreased water activity caused by the scarcity of water molecules. 26,28 This wide ESW overcomes the thermodynamic limit of water electrolysis (1.23 V) and has contributed greatly toward enhancing the energy density of energy storage devices such as batteries and supercapacitors with aqueous electrolytes.…”

Section: Introductionmentioning

confidence: 99%

“…In contrast to the conventional aqueous electrolytes, the highly concentrated aqueous electrolytes known as water‐in‐salt electrolytes (WiSEs) have demonstrated a remarkable extension of the ESW 22‐27 . The first reported WiSE electrolyte using 21 mol kg −1 LiTFSI exhibited a wide ESW in Li‐ion batteries owing to the enhanced Li + and TFSI − interactions and the decreased water activity caused by the scarcity of water molecules 26,28 .…”

Section: Introductionmentioning

confidence: 99%

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The strong correlations between the performance of a KB supercapacitor and the properties of NaClO ₄ and LiFSI electrolytes over wide concentration ranges

Suh

Lee

Park

et al. 2022

Intl J of Energy Research

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Summary Aqueous supercapacitors have received significant attention for their high safety, environmental friendliness, and high ionic conductivity. In particular, the supercapacitors with highly concentrated water‐in‐salt electrolytes (WiSEs) exhibit outstanding characteristics such as wide electrochemical stability windows (2‐3 V) and fast ion transport behaviors. However, previous studies on the WiSE supercapacitors have mostly focused on the effects of high concentrations, and few have examined the influence of the electrolytic structure upon the performance of supercapacitors with various concentrations. Hence, the present study examines how the concentration affects the performance of supercapacitors with various concentrations of NaClO4 (1‐17 mol kg−1) and LiFSI (1‐35 mol kg−1) electrolytes. The study reveals a strong correlation between the electrochemical performance and the concentration‐dependent properties of the electrolyte. Sudden increases in the cell voltages, along with the maximum response speeds of the supercapacitors (−Φ120 Hz = 80.5° and 77.9° for NaClO4 and LiFSI, respectively) are observed in the middle of the concentration range (i.e., at 5‐6 mol kg−1), and are strongly associated with a critical change in the ion and water aggregates in the unique biphasic aqueous electrolyte. The present work is of great importance in gaining a fundamental understanding of the aqueous electrolytes with chaotropic ion salts and is expected to contribute greatly to the development of ultrafast supercapacitors based on the highly conductive electrolytes.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

The strong correlations between the performance of a KB supercapacitor and the properties of NaClO ₄ and LiFSI electrolytes over wide concentration ranges

Suh

Lee

Park

et al. 2022

Intl J of Energy Research

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Dilute Aqueous Hybrid Electrolyte with Regulated Core‐Shell‐Solvation Structure Endows Safe and Low‐Cost Potassium‐Ion Energy Storage Devices

Chen

Lei

Zhang

et al. 2023

Adv Funct Materials

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High‐concentration “water‐in‐salt” (WIS) electrolytes with the wider electrochemical stability window (ESW) can give rise to safe, non‐flammable, and high‐energy aqueous potassium‐ion energy storage devices, thus highlighting the prospect for applications in grid‐scale energy storage. However, WIS electrolytes usually depend on highly concentrated salts, leading to serious concerns about cost and sustainability. Here, an aqueous low‐concentration‐based potassium‐ion hybrid electrolyte is demonstrated with the regulated core‐shell‐solvation structure by using an aprotic solvent, i.e., trimethyl phosphate, to limit the water activity. This aqueous hybrid electrolyte has a low salt concentration (1.6 mol L−1) of potassium trifluoromethanesulfonate but with an expanded ESW up to 3.4 V and the nonflammable property. Based on this dilute aqueous hybrid electrolyte, electrochemical double‐layer capacitors are capable of working within a large voltage range (0–2.4 V) at a wide range of temperatures from −20 to 60 °C. An aqueous potassium‐ion battery consisting of an organic 3,4,9,10‐perylenetetracarboxylic diimide anode, Prussian blue K1.5Mn0.61Fe0.39[Fe(CN)6]0.77·H2O cathode and this dilute aqueous hybrid electrolyte can operate well at rates between 0.2 and 4.0 C and deliver a high energy density of 66.5 Wh kg−1 as well as a durable cycling stability with a capacity retention of 84.5% after 600 cycles at 0.8 C.

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Locking Water Molecules Loss of PAA Hydrogel for Flexible Zinc‐Air Battery with NaCl Doping

Chen

Wang

et al. 2023

Adv Funct Materials

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Flexible zinc‐air batteries have received widespread attention due to their high specific energy and eco‐friendly environment. However, the water in the hydrogel is easily lost to the external environment because of the semi‐open structure zinc‐air batteries, leading to performance degradation of the batteries. Here a saline gel of NaCl‐KOH‐PAA (sodium chloride‐potassium hydroxide‐polyacrylic acid) without soaking in the alkaline solution before use is designed, refining the grid structure of the hydrogel and reducing water loss through NaCl doping. Meanwhile, the gel exhibits no significant decrease in ion conductivity before and after NaCl doping and can maintain stability of around 170 and 150 mS cm−1 at room temperature and −20 °C, respectively. The results demonstrate that the lifetime of flexible zinc‐air batteries with NaCl‐doped hydrogel can be extended by nearly 50%. The NaCl doping gel also displays superior flexibility under extreme physical deformation conditions. Moreover, the phenomenon of hydrogel delamination with NaCl doping is observed and the mechanism of gel water retention is uncovered. These findings will pave the way for developing flexible zinc‐air battery.

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Design strategies and research progress for Water-in-Salt electrolytes

Cited by 42 publications

References 196 publications

The strong correlations between the performance of a KB supercapacitor and the properties of NaClO ₄ and LiFSI electrolytes over wide concentration ranges

The strong correlations between the performance of a KB supercapacitor and the properties of NaClO ₄ and LiFSI electrolytes over wide concentration ranges

Dilute Aqueous Hybrid Electrolyte with Regulated Core‐Shell‐Solvation Structure Endows Safe and Low‐Cost Potassium‐Ion Energy Storage Devices

Locking Water Molecules Loss of PAA Hydrogel for Flexible Zinc‐Air Battery with NaCl Doping

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Design strategies and research progress for Water-in-Salt electrolytes

Cited by 42 publications

References 196 publications

The strong correlations between the performance of a KB supercapacitor and the properties of NaClO 4 and LiFSI electrolytes over wide concentration ranges

The strong correlations between the performance of a KB supercapacitor and the properties of NaClO 4 and LiFSI electrolytes over wide concentration ranges

Dilute Aqueous Hybrid Electrolyte with Regulated Core‐Shell‐Solvation Structure Endows Safe and Low‐Cost Potassium‐Ion Energy Storage Devices

Locking Water Molecules Loss of PAA Hydrogel for Flexible Zinc‐Air Battery with NaCl Doping

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Product

Resources

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The strong correlations between the performance of a KB supercapacitor and the properties of NaClO ₄ and LiFSI electrolytes over wide concentration ranges

The strong correlations between the performance of a KB supercapacitor and the properties of NaClO ₄ and LiFSI electrolytes over wide concentration ranges