Solvent Structure Research Articles

Anionic Solvation Transition at Low Temperatures for Reversible Anodes in Lithium-Oxygen Batteries.

Li-O2 batteries provide a novel technology for electric energy storage due to their high energy density. However, the strong solvent coordination with Li+ at low temperatures impacts their performance and triggers irreversible interfacial reactions on the Li anode. Herein, cyclopentyl methyl ether (CME) is incorporated in a dimethoxyethane (DME)-based electrolyte to realize an anionic solvation transition at low temperatures in Li-O2 batteries. CME featuring a single O coordination site substitutes highly solvating DME in the first solvation sheath, and it induces more anion coordination to Li+ across the room- and low-temperature ranges. The low residence time of CME (66 ps at 25 °C, 382 ps at -40 °C.) in the solvation structures leads to the fast exchange of coordinated CME molecules with Li+ in comparison with DME and facilitates Li+ desolvation at low temperatures. The simultaneously generated inorganic-rich solid electrolyte interphase promotes Li+ transport to improve Li deposition and suppress Li dendrite formation. These enable the Li-O2 battery to present a good cycling stability of 110 cycles with a fixed capacity of 1000 mA h g-1 at -40 °C. This work paves the way for designing novel electrolytes in low-temperature batteries.

Multifunctional fluorinated phosphonate-based localized high concentration electrolytes for safer and high-performance lithium-based batteries

This study introduces a novel fluorinated phosphonate-based additive, Bis(2,2,2-trifluoroethyl)(methoxycarbonylmethyl)phosphonate (BTCMP), in a localized high-concentration electrolyte (LHCE) to address key challenges in lithium metal batteries (LMBs), such as dendritic lithium growth and porous electrode morphology. The pristine LHCE forms a fluorine-rich solid electrolyte interphase (SEI) layer, primarily composed of lithium fluoride (LiF). However, the pristine LHCE suffers from severe electrolyte decomposition, forming a thicker and more resistive cathode electrolyte interphase (CEI), leading to increased impedance and reduced cyclability. Interestingly, Density Functional Theory (DFT) investigations revealed that the BTCMP inclusion modifies the solvation structure by dispersing the aggregates into smaller fragments, facilitating easier Li+ migration than the pristine LHCE. The addition of BTCMP suppresses solvent decomposition as confirmed by an increasing trend in the lowest unoccupied molecular orbital (LUMO) of corresponding LHCE molecules. Further, the presence of BTCMP results in a thinner and more stable CEI, reducing electrolyte decomposition, maintaining better ion transport, and preserving the cathode's structural integrity, as supported by TEM and XPS analysis. The BTCMP-based F-rich LHCE retained 82 % of its initial capacity while maintaining a coulombic efficiency of 99.5 % after 200 cycles in a Li||LNMO cell while the pristine LHCE only retained 47.2 % of initial capacity post-150 cycles. Additionally, the flame-retardant properties of BTCMP-based LHCE highlight its safety compared to commercial electrolytes.

Interfacial Zn2+-solvation regulator towards reversible and stable Zn anode

Aqueous zinc-ion batteries (AZIBs) are fundamentally challenged by the instability of the electrode/electrolyte interface, predominantly due to irreversible zinc (Zn) deposition and hydrogen evolution. Particularly, the intricate mechanisms behind the electrochemical discrepancies induced by interfacial Zn2+-solvation and deposition behavior demand comprehensive investigation. Organic molecules endowed with special functional groups (such as hydroxyl, carboxyl, etc.) have the potential to significantly optimize the solvation structure of Zn2+ and regulate the interfacial electric double layer (EDL). By increasing nucleation overpotential and decreasing interfacial free energy, these functional groups facilitate a lower critical nucleation radius, thereby forming an asymptotic nucleation model to promote uniform Zn deposition. Herein, this study presents a pioneering approach by introducing trace amounts of n-butanol as solvation regulators to engineer the homogenized Zn (H-Zn) anode with a uniform and dense structure. The interfacial reaction and structure evolution are explored by in/ex-situ experimental techniques, indicating that the H-Zn anode exhibits dendrite-free growth, no by-products, and weak hydrogen evolution, in sharp contrast to the bare Zn. Consequently, the H-Zn anode achieves a remarkable Zn utilization rate of approximately 20% and simultaneously sustains a prolonged cycle life exceeding 500 h. Moreover, the H-Zn//NH4V4O10 (NVO) full battery showcases exceptional cycle stability, retaining 95.04% capacity retention after 400 cycles at a large current density of 5 A g−1. This study enlightens solvation-regulated additives to develop Zn anode with superior utilization efficiency and extended operational lifespan.

Additive regulating Li+ solvation structure to construct dual LiF−rich electrode electrolyte interphases for sustaining 4.6 V Li||LiCoO2 batteries

The battery energy density can be improved by raising the operating voltage, however, which may lead to rapid capacity decay due to the continuous electrolyte decomposition and the thickening of electrode electrolyte interphases. To address these challenges, we proposed tripropyl phosphate (TPP) as an additive−regulating Li+ solvation structure to construct a stable LiF–rich electrode carbonate−based electrolyte interphases for sustaining 4.6 V Li||LiCoO2 batteries. This optimized interphases could help reduce the resistance and achieve better rate performance and cycling stability. As expected, the Li||LiCoO2 battery retained 79.4% capacity after 100 cycles at 0.5 C, while the Li||Li symmetric cell also kept a stable plating/stripping process over 450 h at the current density of 1.0 mA/cm2 with a deposited amount of 0.5 mAh/cm2.

Electrochemical CO2 Reduction in Acidic Electrolytes: Spectroscopic Evidence for Local pH Gradients.

Inspired by recent advances in electrochemical CO2 reduction (CO2R) under acidic conditions, herein we leverage in situ spectroscopy to inform the optimization of CO2R at low pH. Using attenuated total reflection surface-enhanced infrared absorption spectroscopy (ATR-SEIRAS) and fluorescent confocal laser scanning microscopy, we investigate the role that alkali cations (M+) play on electrochemical CO2R. This study hence provides important information related to the local electrode surface pH under bulk acidic conditions for CO2R, both in the presence and absence of an organic film layer, at variable [M+]. We show that in an acidic electrolyte, an appropriate current density can enable CO2R in the absence of metal cations. In situ local pH measurements suggest the local [H+] must be sufficiently depleted to promote H2O reduction as the competing reaction with CO2R. Incrementally incorporating [K+] leads to increases in the local pH that promotes CO2R but only at proton consumption rates sufficient to drive the pH up dramatically. Stark tuning measurements and analysis of surface water structure reveal no change in the electric field with [M+] and a desorption of interfacial water, indicating that improved CO2R performance is driven by suppression of H+ mass transport and modification of the interfacial solvation structure. In situ pH measurements confirm increasing local pH, and therefore decreased local [CO2], with [M+], motivating alternate means of modulating proton transport. We show that an organic film formed via in situ electrodeposition of an organic additive provides a means to achieve selective CO2R (FECO2R ∼ 65%) over hydrogen evolution reaction in the presence of strong acid (pH 1) and low cation concentrations (≤0.1 M) at both low and high current densities.

Improved Stability of Single‐Crystal LiCoO2 Cathodes at 4.8 V through Solvation Structure Regulation

AbstractIncreasing the charging cut‐off voltage can significantly improve the capacity of LiCoO2 cathode. However, when the cut‐off voltage exceeds 4.5 V (vs Li/Li+), LiCoO2 undergoes irreversible phase transitions, leading to particle cracking and structural failure. Additionally, the decomposition of the electrolyte compromises the stability of the cathode/electrolyte interface, resulting in diminished battery capacity. Herein, the elements Al, Mg, and Zr are doped into single‐crystal LiCoO2 to enhance the structural stability of LiCoO2. Moreover, a 3 Å zeolite film is used to regulate the solvation structure to enhance the oxidation resistance of the electrolyte. This design enables a more stable cathode/electrolyte interface during high‐voltage cycling. At a cut‐off voltage of 4.8 V, the Li||LiCoO2 battery exhibits an initial discharge capacity of 236.2 mAh g−1 at 0.1 C and maintains 86.6% capacity retention after 100 cycles at 1 C. The pouch full cell, which utilizes a graphite anode and LiCoO2 cathode, operating within a charge–discharge range of 2.8–4.65 V, achieves a specific energy of 276 Wh kg−1 with 81% capacity retention after 200 cycles. This work introduces a desolvated electrolyte into the LiCoO2 battery system, providing a professional approach to addressing the challenges of high‐voltage LiCoO2.

Large scale atomistic and quantum mechanical study of Na+ ion transport in liquid electrolytes for batteries

Lithium–ion batteries (LIBs) have long dominated energy storage markets due to their high energy density and reliability. However, concerns over lithium scarcity and geographic distribution necessitate alternatives. Sodium-ion batteries (SIBs) offer a promising solution due to sodium's abundance, cost-effectiveness, and favorable electrochemical properties. This study investigates Na+ ion transport, aggregation, and performance in various organic electrolytes using molecular dynamics (MD) simulations and density functional theory (DFT) calculations. The electrolytes studied include ethylene carbonate (EC), propylene carbonate (PC), dimethoxyethane (DME), and dimethyl carbonate (DMC) at 320 K. We focused on conductivity, diffusivity, and survival probability of Na+ ions at different salt concentrations. Furthermore, the solvation structure and the binding energy of ions in the electrolytes are thoroughly analyzed. Key findings reveal that at 2 M salt concentration, Na+ ion diffusivity and ionic conductivity follow the order EC>PC>DME>DMC. Increasing salt concentration decreases self–diffusion coefficients of Na+ and PF6− ions across all electrolytes, affecting conductivity. EC shows the highest ionic conductivity at both 1 M and 2 M salt concentrations. These insights suggest that a 2 M NaPF6 concentration in EC optimizes ionic conductivity, making it ideal for high–performance SIBs. This study provides crucial understanding for optimizing electrolytes in SIBs, advancing their development for scalable energy storage solutions.

Regulating Water Activity and Solvation Structure via Zwitterion‐Enhanced Polymer Electrolyte for Long‐Life Zn‐Ion Hybrid Capacitors with Low‐Temperature Applicability

AbstractThe development of aqueous Zn‐based energy storage systems is plagued by poor cyclability and limited operating temperatures caused by Zn anode issues and highly active water. Herein, a frost‐tolerant hydrogel electrolyte (PABCHE) promoted by hydroxyl‐rich β‐cyclodextrin (β‐CD) and zwitterionic betaine (BA) additives is fabricated in situ to protect Zn anodes and enhance low‐temperature adaptability. Both additives synergistically disrupt the hydrogen‐bonding network between water molecules to remarkably reduce the freezing point of PABCHE and alleviate water‐associated side effects. Zwitterionic BA constructs ion‐migration channels and regulate Zn2+ solvation structure, promoting uniform and rapid transport of Zn2+. Additionally, PABCHE renders the Zn2+ homoepitaxially depositing along the (002) plane to achieve dendrite‐free Zn anodes. As a result, versatile PABCHE enables Zn//Zn cells to cycle stably for 1100 and 3600 h at 20 and −20 °C, respectively. Furthermore, the Zn‐ion hybrid capacitors optimized by PABCHE deliver favorable cyclability over 30000 cycles at 20 °C (with a capacity retention of 81.8%) and −20 °C (with a capacity retention of 84.2%). Additionally, PABCHE can be applied as a flexible strain sensor for real‐time monitoring of physiological activities. This work offers valuable insights for developing antifreeze hydrogel electrolytes toward applications of dendrite‐free low‐temperature Zn‐based devices and strain sensors.

A Synergistically Regulated Cathode/Electrolyte Interphase With High Stability and Rapid Zn2+ Migration Toward Advanced Flexible Zinc-Ion Batteries.

Na3V2(PO4)3(NVP), as a representative sodium superionic conductor with a stable polyanion framework, is considered a cathode candidate for aqueous zinc-ion batteries attributed to their high discharge platform and open 3D structure. Nevertheless, the structural stability of NVP and the cathode-electrolyte interphase (CEI) layer formed on NVP can be deteriorated by the aqueous electrolyte to a certain extent, which will result in slow Zn2+ migration. To solve these problems, doping Si elements to NVP and adding sodium acetate (NaAc) to the electrolyte are utilized as a synergistic regulation route to enable a highly stable CEI with rapid Zn2+ migration. In this regard, Ac- competitively takes part in the solvation structure of Zn2+ in aqueous electrolyte, weakening the interaction between water and Zn2+, and meanwhile a highly stable CEI is formed to avoid structural damage and enable rapid Zn2+ migration. The NVPS/C@rGO electrode exhibits a notable capacity of 115.5mAhg-1 at a current density of 50mAg-1 in the mixed electrolyte (3M ZnOTF2+3M NaAc). Eventually, a collapsible "sandwich" soft pack battery is designed and fabricated and can be used to power small fans and LEDs, which proves the practical application of aqueous zinc-ion batteries in flexible batteries.

Co-Regulating Solvation Structure and Hydrogen Bond Network via Bio-Inspired Additive for Highly Reversible ZincAnode.

The feasibility of aqueous zinc-ion batteries for large-scale energy storage is hindered by the inherent challenges of Zn anode. Drawing inspiration from cellular mechanisms governing metal ion and nutrient transport, erythritol is introduced, a zincophilic additive, into the ZnSO4 electrolyte. This innovation stabilizes the Zn anode via chelation interactions between polysaccharides and Zn2+. Experimental tests in conjunction with theoretical calculation results verified that the erythritol additive can simultaneously regulate the solvation structure of hydrated Zn2+ and reconstruct the hydrogen bond network within the solution environment. Additionally, erythritol molecules preferentially adsorb onto the Zn anode, forming a dynamic protective layer. These modifications significantly mitigate undesirable side reactions, thus enhancing the Zn2+ transport and deposition behavior. Consequently, there is a notable increase in cumulative capacity, reaching 6000mA h cm⁻2 at a current density of 5mA cm-2. Specifically, a high average coulombic efficiency of 99.72% and long cycling stability of >500 cycles are obtained at 2mA cm-2 and 1mA h cm-2. Furthermore, full batteries comprised of MnO2 cathode and Zn anode in an erythritol-containing electrolyte deliver superior capacity retention. This work provides a strategy to promote the performance of Zn anodes toward practical applications.

Panthenol Additives with Multiple Coordination Sites Induce Uniform Zinc Deposition and Inhibited Side Reactions for High Performance Aqueous Zinc Metal Battery.

Application of aqueous zinc metal batteries (AZMBs) in large-scale new energy systems (NESs) is challenging owing to the growth of dendrites and frequent side reactions. Here, this study proposes the use of Panthenol (PB) as an electrolyte additive in AZMBs to achieve highly reversible zinc plating/stripping processes and suppressed side reactions. The PB structure is rich in polar groups, which led to the formation of a strong hydrogen bonding network of PB-H2O, while the PB molecule also builds a multi-coordination solvated structure, which inhibits water activity and reduces side reactions. Simultaneously, PB and OTF- decomposition, in situ formation of SEI layer with stable organic-inorganic hybrid ZnF2-ZnS interphase on Zn anode electrode, can inhibit water penetration into Zn and homogenize the Zn2+ plating. The effect of the thickness of the SEI layer on the deposition of Zn ions in the battery is also investigated. Hence, this comprehensive regulation strategy contributes to a long cycle life of 2300h for Zn//Zn cells assembled with electrolytes containing PB additives. And the assembled Zn//NH4V4O10 pouch cells with homemade modules exhibit stable cycling performance and high capacity retention. Therefore, the proposed electrolyte modification strategy provides new ideas for AZMBs and other metal batteries.

Solvation Regulation Reinforces Anion-Derived Inorganic-Rich Interphase for High-Performance Quasi-Solid-State Li Metal Batteries.

Solid-state polymer lithium metal batteries are an important strategy for achieving high safety and high energy density. However, the issue of Li dendrites and inherent inferior interface greatly restricts practical application. Herein, this study introduces tris(2,2,2-trifluoroethyl)phosphate solvent with moderate solvation ability, which can not only complex with Li+ to promote the in-situ ring-opening polymerization of 1,3-dioxolane (DOL), but also build solvated structure models to explore the effect of different solvation structures in the polymer electrolyte. Thereinto, it is dominated by the contact ion pair solvated structure with pDOL chain segments forming less lithium bonds, exhibiting faster kinetic process and constructing a robust anion-derived inorganic-rich interphase, which significantly improves the utilization rate of active Li and the high-voltage resistance of pDOL. As a result, it exhibits stable cycling at ultra-high areal capacity of 20 mAh cm-2 in half cells, and an ultra-long lifetime of over 2000h in symmetric cells can be realized. Furthermore, matched with LiNi0.9Co0.05Mn0.05O2 cathode, the capacity retention after 60 cycles is as high as 96.8% at N/P value of 3.33. Remarkably, 0.7 Ah Li||LiNi0.9Co0.05Mn0.05O2 pouch cell with an energy density of 461Wh kg-1 can be stably cycled for five cycles at 100% depth of discharge.

Simultaneous regulation of the solvation shell and electrode interface via a multifunctional and low-cost additive enabling long-life aqueous Zn metal batteries

Zinc metal batteries have great potential for energy storage applications in smart grids. However, the Zn metal anode presents significant challenges, such as the irrepressible growth of zinc dendrites on the anode’s surface, the accumulation of inert products, and the hydrogen evolution reaction. These issues can lead to the decreased cycling stability of the anode. To solve these problems, we developed a method of adding sodium p-toluenesulfonate to the electrolyte to protect the zinc metal anode. Density functional theory calculations show that the −SO3 functional group in sodium p-toluenesulfonate can alter the solvation structure of Zn2+ and adsorb onto the surface of the Zn metal anode. Thus, the Zn||Zn symmetric cell could be cycled stably for over 2000 h, whereas the Zn||Cu half-cell could be cycled stably for over 5000 cycles, with an average Coulombic efficiency of 99.87 %. The Zn||I2 full cell could be cycled stably for 10,000 cycles under test conditions of 1A/g, and the capacity retention rate was 95.49 %. This study provides insights into the use of additives in the electrolytes of zinc metal batteries.

Structural and Electronic Properties of Novel Azothiophene Dyes: A Multilevel Study Incorporating Explicit Solvation Effects.

Among azobenzene derivatives, azothiophenes represent a relatively recent family of compounds that exhibit similar characteristics as dyes and photoreactive systems. Their technological applications are extensive thanks to the additional design flexibility conferred by the heteroaromatic ring. In this study, we present a comprehensive investigation of the structural and electronic properties of novel dyes derived from 3-thiophenamine, utilizing a multilevel approach. We thoroughly examined the potential energy surfaces of the E and Z isomers for three molecules, each bearing different substituents on the phenyl ring at the para position relative to the diazo group. This exploration was conducted through quantum chemistry calculations at various levels of theory, employing a continuum solvent model. Subsequently, we incorporated an explicit solvent (a dimethyl sulfoxide-water mixture) to simulate the most stable isomers using classical molecular dynamics, delivering a clear picture of the local solvation structure and intermolecular interactions. Finally, a hybrid quantum mechanics/molecular mechanics (QM/MM) approach was employed to accurately describe the evolution of the solutes' properties within their environment, accounting for finite temperature effects.

Molecular-Resolution Imaging of Ionic Liquid/Alkali Halide Interfaces with Varied Surface Charge Densities via Atomic Force Microscopy.

When in contact with charged solid surfaces, ionic liquids (ILs) are known to form solvation structures consisting of alternating cation and anion layers. This phenomenon is considered to originate from the adsorption layer of counterions overcompensating the surface charge, so-called overscreening. However, the response of these layers to surfaces with near-zero or extremely high surface charge density (σ) remains inadequately understood. Here, we probe the solvation structure of ILs on alkali halide surfaces with varied surface orientations: nearly zero-charged RbI(100) and highly charged RbI(111), by employing frequency modulation atomic force microscopy with atomic resolution. Two commonly used ILs are examined in this study: 1-methyl-1-propylpyrrolidinium bis(trifluoromethylsulfonyl)imide ([C3mpyr][NTf2]) and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([C2mim][NTf2]). On RbI(100) surfaces with near zero σ, we observe alternating cation and anion layers, diverging from the previously proposed monolayer model for IL/alkali halide(100) interfaces. These results support the argument that overscreening occurs under low σ, even approaching zero, and reconcile conflicting experimental conclusions about low σ systems. On RbI(111) surfaces with high σ, we identify solvation structures consisting of two consecutive counterion layers. This structure aligns with the theoretically predicted crowding; a phenomenon rarely observed in commonly used ILs due to typically unreachable σ in electrochemical IL/electrode systems. Our findings indicate that alkali halide(111) surfaces are potentially valuable for exploring the crowding phenomenon in ILs, addressing the current scarcity of experimental observations.

Multiple Functional Bonds Integrated Interphases for Long Cycle Sodium‐Ion Batteries

AbstractSodium‐ion batteries (SIBs) have garnered significant interest as one of the most promising energy suppliers for power grid energy storage. However, the poor electrode/electrolyte interfacial stability leads to continual electrolyte decomposition and transition metal dissolution, resulting in rapid performance degradation of SIBs. In this work, we propose a strategy integrating multiple functional bonds to regulate electrode/electrolyte interphase by triple‐coupling of succinonitrile (SN), sodium hexafluorophosphate (NaPF6) and fluorinated ethylene carbonate (FEC). Theoretical calculation and experiment results show that the solvation structure of Na+ and ClO4− is effectively reconfigured by the solvated FEC, SN and PF6− in PC‐based carbonate electrolyte. The newly developed electrolyte demonstrates increased Na+‐FEC coordination, weakened interaction of Na+‐PC and participation of SN and PF6− anions in solvation, resulting in the formation of a conformal interfacial layer comprising of sodium oxynitrides (NaNxOy), sodium fluoride (NaF) and phosphorus oxide compounds (NaPxOy). Consequently, a 3 Ah pouch full cell of hard carbon//NaNi1/3Fe1/3Mn1/3O2 exhibits an excellent capacity retention of 90.4 % after 1000 cycles. Detailed postmortem analysis of interface chemistry is further illustrated by multiple characterization methods. This study provides a new avenue for developing electrolyte formulations with multiple functional bonds integrated interphases to significantly improve the long‐term cycling stability of SIBs.

Multiple Functional Bonds Integrated Interphases for Long Cycle Sodium-Ion Batteries.

Sodium-ion batteries (SIBs) have garnered significant interest as one of the most promising energy suppliers for power grid energy storage. However, the poor electrode/electrolyte interfacial stability leads to continual electrolyte decomposition and transition metal dissolution, resulting in rapid performance degradation of SIBs. In this work, we propose a strategy integrating multiple functional bonds to regulate electrode/electrolyte interphase by triple-coupling of succinonitrile (SN), sodium hexafluorophosphate (NaPF6) and fluorinated ethylene carbonate (FEC). Theoretical calculation and experiment results show that the solvation structure of Na+ and ClO4 - is effectively reconfigured by the solvated FEC, SN and PF6 - in PC-based carbonate electrolyte. The newly developed electrolyte demonstrates increased Na+-FEC coordination, weakened interaction of Na+-PC and participation of SN and PF6 - anions in solvation, resulting in the formation of a conformal interfacial layer comprising of sodium oxynitrides (NaNxOy), sodium fluoride (NaF) and phosphorus oxide compounds (NaPxOy). Consequently, a 3 Ah pouch full cell of hard carbon//NaNi1/3Fe1/3Mn1/3O2 exhibits an excellent capacity retention of 90.4 % after 1000 cycles. Detailed postmortem analysis of interface chemistry is further illustrated by multiple characterization methods. This study provides a new avenue for developing electrolyte formulations with multiple functional bonds integrated interphases to significantly improve the long-term cycling stability of SIBs.

Understanding and tuning intermolecular interactions of the electrolyte solvation structure for low-temperature lithium-based batteries

Electrolytes dictate the performance of low-temperature electrochemical energy storage devices, especially lithium-based batteries. The electrolyte solvation structure is critical for the ionic transport and charge-transfer kinetics as well as interfacial stabilities. Thus, an in-depth understanding of the constitutive relationship between different electrolyte components and low-temperature battery performance at the molecular level, and the effect of low temperature on the interactions between various molecules within the electrolyte solvation structure is critical for the rational design on the advanced low-temperature electrolytes. Herein, a systematically in-depth understanding of the intermolecular interactions within lithium-ion (Li+) solvation structure at low temperatures is provided. The research progress on the design of solvation structures for low-temperature lithium-based batteries is summarized from the perspective of regulating the interactions among cations, anions and solvents in the solvation structures. This review highlights the critical role of solvation structures on low-temperature battery performance that help advance the low-temperature battery chemistry.

Trace alcohol ether electrolytes with dual-site hydrogen bonds and modulated solvation structures for ultralong-life zinc-ion batteries

Aqueous zinc-ion batteries (AZIBs) are highly regarded for their affordability, stability, safety, and eco-friendliness. Nevertheless, their practical application is hindered by severe side reactions and the formation of zinc (Zn) dendrites on the Zn metal anode surface. In this study, we employ tetrahydrofuran alcohol (THFA), an efficient and cost-effective alcohol ether electrolyte, to mitigate these issues and achieve ultralong-life AZIBs. Theoretical calculations and experimental findings demonstrate that THFA acts as both a hydrogen bonding donor and acceptor, effectively anchoring H2O molecules through dual-site hydrogen bonding. This mechanism restricts the activity of free water molecules. Moreover, the two oxygen (O) atoms in THFA serve as dual solvation sites, enhancing the desolvation kinetics of [Zn(H2O)6]2+ and improving the deposition dynamics of Zn2+ ions. As a result, even trace amounts of THFA significantly suppress adverse reactions and the formation of Zn dendrites, enabling highly reversible Zn metal anodes for ultralong-life AZIBs. Specifically, a Zn-based symmetric cell containing 2 % THFA achieves an ultralong cycle life of 8,800 h at 0.5 mA cm−2/0.5 mAh cm−2, while a Zn//VO2 full cell containing 2 % THFA maintains a remarkable 80.03 % capacity retention rate at 5 A g−1 over 2,000 cycles. This study presents a practical strategy to develop dendrite-free, cost-effective, and highly efficient aqueous energy storage systems by leveraging alcohol ether compounds with dual-site hydrogen bonding capabilities.

Balancing the Co‐Solvent Content in High Entropy Aqueous Electrolytes to Obtain 2.2 V Symmetric Supercapacitors

AbstractThe energy storage capability of supercapacitors (SCs) strongly depend on the operating cell voltage of the electrolytes of choice. In this regard, the inherent distinct electrochemical stability of cations and anions is a factor of relevance for the operating cell voltage. The use of double salts sharing one ion has been described as an approach to circumvent this problem, but whether modifying the solvation structure of cations and anions with different solvent molecules (coordinating and/or non‐coordinating) could help balance their electrochemical stability in SCs has not yet been fully addressed. In this work, electrolytes are prepared by combining solvent mixtures and double salts, specifically 1‐ethyl‐3‐methylimidazolium bis(trifluoromethylsulfonyl)imide (EMIMTFSI) and 1‐ethyl‐3‐methylimidazolium tetrafluoroborate (EMIMBF4) in mixtures of water (H2O) and dimethysulfoxide (DMSO) as coordinating co‐solvents and acetonitrile (CH3CN) as a weakly coordinating one. It is found that the presence of this latter one helped to enhanced the cation solvation structure (above 9). This increase of the entropic features allows operating at cell voltages of up to 2.2 V and the subsequent enhancement of the energy storage capabilities and capacitance retentions (up to 15 Wh kg−1 and ≈87% after 10 000 cycles, respectively).