Desolvation Energy Research Articles

Enhanced kinetics and stability for aqueous Zn battery enabled by low-cost additive chemistry

Rechargeable aqueous zinc(Zn) batteries are a sustainable alternative to lithium-based energy storage devices due to their high safety, low cost, and scalability. Unfortunately, the Zn/Zn2+ redox chemistry is significantly plagued by undesirable interface caused by the instability of water, which directly dictates the low Zn reversibility and dendrite growth behavior. Here, we report an aqueous electrolyte in which low-cost ammonium dihydrogen phosphate is utilized as an electrolyte additive to enable the in-situ construction of phosphate-based interphase on the Zn-metal surface. Importantly, such interphase not only effectively eliminates water-related parasitic reactions and enables a highly reversible Zn deposition/dissolution, as demonstrated by its high Coulombic efficiency of 99.3 %, but also contributes a dendrite-free Zn morphology. Apart from the improved stability of the Zn anode, the addition of NH4H2PO4 also grants the enhanced reaction kinetics of Zn2+, bringing a lower Zn2+ de-solvation energy barrier and much-improved rate performance. Benefiting from the synergistic factors, excellent cycling performances of the Zn0.25V2O5·nH2O (ZVO)/Zn batteries are guaranteed. Additionally, a 31.2 mAh ZVO/Zn pouch cell also demonstrates a stable long life of 400 cycles, and capacity retention of 67.8 % is also retained. The low-cost and efficient electrolyte strategy points out a promising direction for practical Zn batteries.

Breaking solvation dominance of ethylene carbonate via molecular charge engineering enables lower temperature battery

Low temperatures severely impair the performance of lithium-ion batteries, which demand powerful electrolytes with wide liquidity ranges, facilitated ion diffusion, and lower desolvation energy. The keys lie in establishing mild interactions between Li+ and solvent molecules internally, which are hard to achieve in commercial ethylene-carbonate based electrolytes. Herein, we tailor the solvation structure with low-ε solvent-dominated coordination, and unlock ethylene-carbonate via electronegativity regulation of carbonyl oxygen. The modified electrolyte exhibits high ion conductivity (1.46 mS·cm−1) at −90 °C, and remains liquid at −110 °C. Consequently, 4.5 V graphite-based pouch cells achieve ~98% capacity over 200 cycles at −10 °C without lithium dendrite. These cells also retain ~60% of their room-temperature discharge capacity at −70 °C, and miraculously retain discharge functionality even at ~−100 °C after being fully charged at 25 °C. This strategy of disrupting solvation dominance of ethylene-carbonate through molecular charge engineering, opens new avenues for advanced electrolyte design.

Spatially Selective Solvation Structure by Electronegative Micro-Arrays for Stable Lithium-Metal Anode Interface.

For electrolytes with conventional lithium salt concentration, it is not easy to generate sufficient anion-derived beneficial inorganic components to stabilize the electrolyte-lithium metal anode interface due to the repulsion of the free-state anions by the anode. In this study, the above issues are solved through the strong interaction between electronegative materials and lithium ions (Li+ ). A locally high Li+ concentration strategy is proposed by preparing micro-arrays of electronegative nano-hydroxyapatite (nHA) on the Cu foil. It is found that the oxygenatoms in the phosphate group (-PO4 ) of the nHA can strongly adsorb Li+ to form a locally Li+ -rich region, which increases the probability of anions interacting with Li+ . The formation of more Li+ -coordinated anions at the electrolyte-anode interface can reduce the Li+ de-solvation energy barrier, and enable the anions to completely decompose into lithium fluoride (LiF) and lithium nitride (Li3 N) on the Li metal anode. The interfacial transfer dynamics is accelerated and the Li dendrites are effectively suppressed. Under high current density, the anode exhibits a long lifespan with high Coulombic efficiency and small polarization voltage. The nHA micro-arrays achieve the targeted solvation structure at the electrolyte-anode interface while ensuring conventional lithium salt concentration in the bulk electrolyte.

Metal-Free Eutectic Electrolyte with Weak Hydrogen Bonds for High-Rate and Ultra-Stable Ammonium-Ion Batteries.

As the need for sustainable battery chemistry grows, non-metallic ammonium ion (NH4 + ) batteries are receiving considerable attention because of their unique properties, such as low cost, nontoxicity, and environmental sustainability. In this study, the solvation interactions between NH4 + and solvents are elucidated and design principles for NH4 + weakly solvated electrolytes are proposed. Given that hydrogen bond interactions dominate the solvation of NH4 + and solvents, the strength of the solvent's electrostatic potential directly determines the strength of its solvating power. As a proof of concept, succinonitrile with relatively weak electronegativity is selected to construct a metal-free eutectic electrolyte (MEE). As expected, this MEE is able to significantly broaden the electrochemical stability window and reduce the solvent binding energy in the solvation shell, which leads to a lower desolvation energy barrier and a fast charge transfer process. As a result, the as-constructed NH4 -ion batteries exhibit superior reversible rate capability (energy density of 65Whkg-1 total active mass at 600Wkg-1 ) and unprecedent long-term cycling performance (retention of 90.2% after 1000 cycles at 1.0Ag-1 ). The proposed methodology for constructing weakly hydrogen bonded electrolytes will provide guidelines for implementing high-rate and ultra-stable NH4 + -based energy storage systems.

Stable Aluminum Metal Anode Enabled by Dual-Functional Molybdenum Nanoparticles.

Constructing robust anode with strong aluminophilicity and rapid desolvation kinetics is essential for achieving high utilization, long-term durability, and superior rate performance in Al metal-based energy storage, yet remains largely unexplored. Herein, molybdenum nanoparticles embedded onto nitrogen-doped graphene (Mo@NG) are designed and prepared as Al host to regulate the deposition behavior and achieve homogeneous Al plating/stripping. The monodispersed Mo nanoparticles reduce the desolvation energy barrier and promote the deposition kinetics of Al. Additionally, Mo nanoparticles act as aluminophilic nucleation sites to minimize the Al nucleation overpotential, further guiding uniform and dense Al deposition. As a result, the dual-functional Mo@NG endows Al anodes with low voltage hysteresis, reversible Al plating/stripping with high coulombic efficiency, and excellent high-rate capability under 5mA cm-2. Moreover, the as-designed Al metal full batteries deliver a high capacity retention of 92.8% after 3000 cycles at 1 A g-1. This work provides an effective solution to optimize the electrochemical properties of Al metal anode from the perspective of desolvation and deposition reactions, towards the development of high-safety and long-cycling aluminum-ion batteries.

Synergistically Stabilizing Zinc Anodes by Molybdenum Dioxide Coating and Tween 80 Electrolyte Additive for High-Performance Aqueous Zinc-Ion Batteries.

Recently, aqueous zinc-ion batteries (ZIBs) have become increasingly attractive as grid-scale energy storage solutions due to their safety, low cost, and environmental friendliness. However, severe dendrite growth, self-corrosion, hydrogen evolution, and irreversible side reactions occurring at Zn anodes often cause poor cyclability of ZIBs. This work develops a synergistic strategy to stabilize the Zn anode by introducing a molybdenum dioxide coating layer on Zn (MoO2@Zn) and Tween 80 as an electrolyte additive. Due to the redox capability and high electrical conductivity of MoO2, the coating layer can not only homogenize the surface electric field but also accommodate the Zn2+ concentration field in the vicinity of the Zn anode, thereby regulating Zn2+ ion distribution and inhibiting side reactions. MoO2 coating can also significantly enhance surface hydrophilicity to improve the wetting of electrolyte on the Zn electrode. Meanwhile, Tween 80, a surfactant additive, acts as a corrosion inhibitor, preventing Zn corrosion and regulating Zn2+ ion migration. Their combination can synergistically work to reduce the desolvation energy of hydrated Zn ions and stabilize the Zn anodes. Therefore, the symmetric cells of MoO2@Zn∥MoO2@Zn with optimal 1 mM Tween 80 additive in 1 M ZnSO4 achieve exceptional cyclability over 6000 h at 1 mA cm-2 and stability (>700 h) even at a high current density (5 mA cm-2). When coupling with the VO2 cathode, the full cell of MoO2@Zn∥VO2 shows a higher capacity retention (82.4%) compared to Zn∥VO2 (57.3%) after 1000 cycles at 5 A g-1. This study suggests a synergistic strategy of combining surface modification and electrolyte engineering to design high-performance ZIBs.

Polar Organic Molecules Inserted in Vanadium Oxide with Enhanced Reaction Kinetics for Promoting Aqueous Zinc‐Ion Storage

AbstractThe Zn2+ sluggish kinetics resulting from high desolvation barriers of Zn(H2O)62+ in the electrode/electrolyte interface restricts the practical application of Zn‐ion batteries (ZIBs). Herein, ethylene glycol (EG) molecules are inserted into V2O5·3H2O to form V‐EG nanoarray structures to improve the Zn2+ diffusion rate. Unlike most efforts focused on improving interlayer spacing and structural stability, the influence of EG on the Zn2+ desolvation and Zn2+ storage process are the main goals. Based on experimental and theoretical analysis, EG molecules are confirmed to participate in the reshaping of V2O5·3H2O morphology and Zn2+ solvation structure, which is beneficial to enhance the reaction kinetics and specific capacity. The polar group of the EG molecule leads it anchored in the VO skeleton and decreases the desolvation energy, while the steric hindrance of the low polarity group liberalizes Zn2+ transfer reversibly in the VO skeleton. Therefore, V‐EG delivers a higher ion diffusion coefficient and lower kinetic barrier. As expected, V‐EG exhibits a high specific capacity of 553 mA h g−1 at 0.3 A g−1 and a long cycle life of 10 000 cycles at 20 A g−1. This work provides a strategy to decrease the desolvation energy of Zn2+ in the interface of cathode materials toward advanced ZIBs.

Weakly Binding Molecules‐Based Fast Charging Li‐Ion Batteries

AbstractFast charging of Li‐ion batteries (LIBs) beyond standard 0.3 C (charged in 3.3 h) are desperately pursued but hindered by sluggish desolvation kinetics of ethylene carbonate‐based traditional electrolyte, and Li‐plating and dendrites growth at graphite anode and fire hazard. Herein, a new class of weakly binding all linear molecules‐based nonflammable electrolyte (WNLE) is reported, comprising 1 m LiPF6 in ethyl methyl carbonate and 2,2,2‐trifluoroethyl acetate with additives for 10–20 times faster charging LIBs than traditional ones. The critical benefits of WNLE are 44% lower viscosity, 62% higher Li+ diffusion coefficient, 20% higher Li+ transference number, and 17% lower desolvation energy, which promotes diffusion kinetics and desolvation kinetics of Li+ in the vicinity of graphite anode enabling dendrites‐free LIB, along with nonflammability. Under 3 C (charged in 20 min), WNLE‐based industrial 800 mAh graphite//LiNi0.8Mn0.1Co0.1O2 (high active mass 13 mg cm−2) Li‐ion pouch battery achieves outstanding 700 cycles, delivering 82% capacity retention and high Coulombic efficiencies ≈100%. Robust solid electrolyte interphase layers formed at the anode and cathode mitigate interfacial failures, making fast charge to 7 C and longer cycle‐life. This new class of electrolyte formulation is a promising solution and a new opportunity to realize safe and long operation of fast‐charging LIBs for practical applications.

Oscillation Charging Dynamics in Nanopore Supercapacitors with Organic Electrolyte.

Nanopore electrodes have the potential to enhance the energy density of supercapacitors but tend to reduce charging dynamics, consequently impacting power density. A comprehensive understanding of their charging mechanisms can provide insights into how to boost charging dynamics. In this work, we conducted constant-potential-based molecular dynamics simulations to explore the charging mechanism of nanopore supercapacitors with organic electrolytes. Contrary to the traditional understanding associating larger pore sizes with faster charging, our results found a complex oscillatory behavior of the charging rate, correlating with nanopore size in organic electrolytes. An anomalously increased charging dynamics was found in the 0.9 nm pore. This anomalous enhancement can be attributed to the improved in-pore ion diffusion and reduced desolvation energy, owing to the orientation transition of the solvate molecules. These results pave a new way for innovative designs of nanoporous electrode supercapacitors that can enlarge both power and energy densities.

Boosting Fast‐Charging Capability of High‐Voltage Li Metal Batteries with Ionic Liquid Modified Ethereal Electrolyte

AbstractGiven the high compatibility with Li metal anodes, ethereal electrolytes have found widespread use in Li metal batteries. Unfortunately, their applications in high‐voltage Li metal batteries are hampered by a limited electrochemical window. In this study, a diluted ethereal electrolyte (with Li salt concentration < 1.5 m) is developed containing 1 m lithium bis(fluorosulfonyl) imide (FSI) and 0.3 m LiNO3 in a N‐methyl‐N‐propylpiperidinium bis(trifluoromethanesulfonyl)imide (PP13TFSI):dimethyl ether (DME) (v:v = 1:4) mixture for Li metal batteries with an aggressive high‐voltage cathode via the formation of an anion‐enriched solvation sheath. In contrast to high‐concentration electrolytes, the formation of the anion‐enriched solvation sheath in this design is facilitated by the addition of ionic liquids. Further theoretical calculations indicate that the presence of FSI− and NO3− anions in the first solvation sheath weakens the desolvation energy of the DME solvent, suggesting a faster desolvation process at the electrode interphase. Consequently, the designed electrolyte enables long‐term cycling of Li || LiNi0.8Co0.1Mn0.1O2 (NCM811) full cells over 1000 cycles at a high rate of 10 C. More notably, it also allows for a long cycle life of 100 cycles under a high rate of 5 C, even with limited negative capacity to positive capacity (N/P) ratio of 1.

Self-Adaptive Liquid Film: Dynamic Realization of Dendrite-Free Zn Deposition Toward Ultralong-Life Aqueous Zn Battery.

The poor reversibility and stability of Zn metal anode (ZMA) caused by uncontrolled Zn deposition behaviors and serious side reactions severely impeded the practical application of aqueous Zn metal battery. Herein, a liquid-dynamic and self-adaptive protective layer (LSPL) was constructed on the ZMA surface for inhibiting dendrites and by-products formation. Interestingly, the outer LSPL consists of liquid perfluoropolyether (PFPE), which can dynamically adapt volume change during repeat cycling and inhibit side reactions. Moreover, it can also decrease the de-solvation energy barrier of Zn2+ by strong interaction between C-F bond and foreign Zn2+ , improving Zn2+ transport kinetics. For the LSPL inner region, in-situ formed ZnF2 through the spontaneous chemical reaction between metallic Zn and part PFPE can establish an unimpeded Zn2+ migration pathway for accelerating ion transfer, thereby restricting Zn dendrites formation. Consequently, the LSPL-modified ZMA enables reversible Zn deposition/dissolution up to 2000h at 1mA cm-2 and high coulombic efficiency of 99.8% at 4mA cm-2 . Meanwhile, LSPL@Zn||NH4 V4 O10 full cells deliver an ultralong cycling lifespan of 100 00 cycles with 0.0056% per cycle decay rate at 10 A g-1 . This self-adaptive layer provides a new strategy to improve the interface stability for next-generation aqueous Zn battery.

Constructing amphipathic molecular layer to assists de-solvation process for dendrite-free Zn anode

Due to the excellent safety feature, substantial theoretical capacity and abundant zinc reserves in the earth's crust, Aqueous Zn-ion batteries (AZIBs) are promising as the next generation energy storage system. However, the problem of dendrite growth and the related side reactions in Zn surface limit their further development and application. Herein, an amphipathic molecular layer (Polyacrylic Acid, named as PAA) is constructed on Zn surface to hinder the side reactions and zinc dendrites by intervening the de-solvation process. It is found that the rich hydroxyl group in polyacrylic acid is very hydrophilic. On the contrary, hydrocarbon group on the other side is nearly hydrophobic. The amphiphilic PAA molecular layer on Zn surface results in lower de-solvation energy barrier, thus inhibits the decomposition of water and related side reactions. Additionally, the accumulate abundant negative charge at the interface of polyacrylic acid and Zn surface can attract homogeneous deposition of Zn atoms. Using only 0.01 M PAA as additive in 2.0 M ZnSO4 electrolyte. Zn||Zn symmetric cells expresses a superior cycling stability of 4643 h (5 mA cm−2, 1 mAh cm−2). This study provides new insights into the long-life AZIBs modulated by amphipathic molecular layer.

Inhibiting zinc dendrites and side reactions enabled by solvation structure regulation and facile de-solvation process

Rechargeable aqueous zinc-ion batteries show great promise as next-generation energy storage devices given their advantages of low cost and high safety. However, dendrite growth and detrimental side reactions result in poor reversibility of Zn anodes. Here, TEG molecules were introduced as additives to regulate the solvation structure through occupying the position of water molecules in the solvation shell, which also further decreasing the de-solvation energy barrier. The lower de-solvation energy barrier is beneficial for the dissociation of solvation water molecules and help to restrain the water decomposition and the related by-products. Theoretical studies also reveal that TEG is more easily adsorbed on the surface of zinc than water molecules, electrons are more easily transferred from the TEG molecule to the zinc foil, thus promoting the uniform deposition of zinc atoms. Benefiting from the solvation structure regulation and facile de-solvation process of Zn2+, Zn/Zn symmetric cell achieve a long cycling life of 2000 h at the current density and capacity of 1 mA cm−2 and 1mAh cm−2, and a MnO2-Zn full cell reach a superior stability of 3000 cycles at the current density of 1000 mA g−1.

Highly Reversible Zn Metal Anode with Low Voltage Hysteresis Enabled by Tannic Acid Chemistry.

The zinc dendrites and side reactions formed on the zinc anode have greatly hindered the development of aqueous zinc-ion batteries (ZIBs). Herein, we introduce tannic acid (TA) as an additive in the ZnSO4 (ZSO) electrolyte to enhance the reversible Zn plating/stripping behavior. TA molecules are found to adsorb onto the zinc surface, forming a passivation layer and replacing some of the H2O molecules in the Zn2+ solvation sheath to form the [Zn(H2O)6-xTAx]2+ complex; this process effectively prevents side reactions. Moreover, the lower desolvation energy barrier of the [Zn(H2O)6-xTAx]2+ structure facilitates uniform Zn metal deposition and enables a stable plating/stripping lifespan of 2500 h with low voltage hysteresis (53 mV at 0.5 mA cm-2) as compared to the ZSO electrolyte (167 h and 104 mV). Additionally, the incorporation of the MnO2 cathode in the TA + ZSO electrolyte shows improved cycling capacity retention, from 64% (ZSO) to 85% (TA + ZSO), after 250 cycles at 1 A g-1, demonstrating the effectiveness of the TA additive in enhancing the performance of ZIBs.

Understanding the Energetics of Ion Intercalation in Lithium-Ion Batteries

Researchers around the world are working to increase the energy efficiency and the energy density of lithium-ion batteries. However, the mechanism and the factors influencing the charge transfer (CT) kinetics at the electrode-electrolyte interface remain poorly understood. Recently, Fraggedakis et al. [1] proposed the theory of coupled ion-electron transfer (CIET) to explain the process of charge transfer at the electrode-electrolyte interfaces. In this work, we provide deep atomistic understanding of the interfacial CT mechanism, the underlying microscopic steps, and the factors influencing the CT rates in a Li-ion battery. In addition, we connect our computational results with the experimental measurements and Marcus-like theories of charge transfer (viz. CIET [1]).Using state-of-the-art computational techniques, such as metadynamics and molecular dynamics simulations, we model the electrode-electrolyte interface and compute the free energy profiles of Li-ion adsorption at the interface, subsequent ion-desolvation, and intercalation into the cathode. Specifically, we study the adsorption of Li+ ion on LixCoO2 surface for different (i) electrolytes, (ii) Li+ concentrations in electrolyte, (iii) salt compositions, and (iv) temperatures to uncover the trends governing charge transfer kinetics. Using the obtained free energy profiles of Li+ desolvation and intercalation at the solid-liquid interface, we provide estimation of the adsorption and desolvation energy at the interface and identify the key energy barrier which acts as the roadblock for ion transfer in Li-ion batteries. Based on this identified key kinetic barrier, we then propose strategies to tune the energy barrier for ion transport. In addition, we identify important thermo-physical observations that can explain the existing experimental trends. For instance, we find that increasing the salt concentration in the electrolyte increases the accessible solvation states to Li+ ion, thereby changing the energy barrier for the Li+ ion to intercalate into the electrode, and thus leading to higher currents. Moreover, we find that changing the salt from LiPF6 to LiClO4 further modifies the energy landscape of Li+ ion, leading to increased measured experimental kinetics as well. This work builds an understanding of the influence of various effects, such as salt concentration and electrolyte composition, on the Li+ transport properties at interfacial regions. Our computational framework can also provide descriptors to enhance the performance and stability of lithium-ion batteries.

Synergetic modulation on solvation structure and electrode interface to achieve lithium-ion batteries cycled at ultra-low temperature

The performance of rechargeable lithium-ion batteries (LIBs) in cold environments remains a challenge due to the insufficient ionic conductivity of electrolyte and lithium plating at graphite anodes. Herein, we demonstrate that the synergistic effect of ether-based electrolyte and niobium oxide with high intercalation potential can significantly improve the low-temperature charging/discharging performance of LIBs. Theoretical calculations and in-situ characterizations prove that the weak desolvation energy of electrolyte and the strong binding energy Li+-O bridging coordination synergistically accelerate the interfacial reaction kinetics. The full cells by coupling the niobium oxide anode with LiFePO4 cathode show 95.6% of the initial capacity after 500 cycles at −30 °C, and exhibit excellent rechargeability at −50 °C. This work verifies that the synergism of solvating power of solvent and Li+ intercalation behavior is crucial in low-temperature LIBs.

Influence of MXene-assisted multifunctional interface on zinc deposition toward highly reversible dendrite-free zinc anodes

The ever-growing demand for safe and renewable energy storage systems has driven the renaissance of aqueous zinc (Zn)-metal batteries (ZMBs). Zn metal has the characteristics of high specific capacity, low cost, environmental friendliness, and intrinsic safety, but severe side reactions and Zn dendrite growth lead to low Coulombic efficiency and short cycle life of Zn metal anode, which restricts the commercial development of rechargeable aqueous ZMBs. Herein, a Ti3C2Tx MXene-derived ZnF2-rich multifunctional interfacial layer is prepared. In this architecture, the as-formed ZnF2-rich layer can redistribute Zn-ion flux on the electrode/electrolyte surface and suppress side reactions. Meanwhile, the results indicate that the ZnF2 can lower the desolvation energy barrier of Zn ions and enhance the Zn-ion transfer kinetics. Accordingly, the Zn@MXene anode delivers a long cycle life over 800 h at the current density of 5.0 mA cm−2 with a capacity of 5.0 mAh cm−2. Surprisingly, the Zn@MXene anode can still achieve dendrite-free Zn deposition for more than 320 h even at the current density of 10.0 mA cm−2 with a capacity of 10.0 mAh cm−2. Additionally, the assembled Zn@MXene//VO2 full-cell exhibits better cycling stability and more excellent rate performance compared to the pristine Zn//VO2 full-cell, implying the potential of this idea to develop high-power rechargeable aqueous Zn-ion batteries.

HydraMap v.2: Prediction of Hydration Sites and Desolvation Energy with Refined Statistical Potentials.

The complex network of water molecules within the binding pocket of a target protein undergoes alterations upon ligand binding, presenting a significant challenge for conventional molecular modeling methods to accurately characterize and compute the associated energy changes. We have previously developed an empirical method, HydraMap (J. Chem. Inf. Model. 2020, 60, 4359-4375), which employs statistical potentials to predict hydration sites and compute desolvation energy, achieving a reasonable balance between accuracy and speed. In this work, we present its improved version, namely, HydraMap v.2. We updated the statistical potentials for protein-water interactions through an analysis of 17 042 crystal protein structures. We also introduced a new feature to evaluate ligand-water interactions by incorporating statistical potentials derived from the solvated structures of 9878 small organic molecules produced by molecular dynamics simulations. By combining these potentials, HydraMap v.2 can predict and compare the hydration sites in a binding pocket before and after ligand binding, identifying key water molecules involved in the binding process, such as those forming bridging hydrogen bonds and unstable ones that can be replaced. We demonstrated the application of HydraMap v.2 in explaining the structure-activity relationship of a panel of MCL-1 inhibitors. The desolvation energies calculated by summing the energy change of each hydration site before and after ligand binding showed good correlation with known ligand binding affinities on six target proteins. In conclusion, HydraMap v.2 offers a cost-effective solution for estimating the desolvation energy during protein-ligand binding and also is practical in guiding lead optimization in structure-based drug discovery.

Highly Reversible Zn Metal Anodes Enabled by Increased Nucleation Overpotential

HighlightsThe nucleation overpotential was regulated by sodium L-tartrate to drive smaller critical size of Zn nucleus and accelerate the nucleation rate.The L-tartrate anions and sodium ions can increase de-solvation energy barrier suitably and hinder the agglomerative Zn deposition resepectively.Nucleation overpotential in modified electrolyte could increase from 28.3 to 45.9 mV, and high Zn utilization rate of 80% at current density of 10 mA cm−2 can be achieved.

Wide-Potential-Window Bimetallic Hydrated Eutectic Electrolytes with High-Temperature Resistance for Zinc-Ion Hybrid Capacitors.

Aqueous zinc-ion hybrid capacitors (ZHCs) are considered ideal energy-storage devices. However, the common aqueous Zn2+ -containing electrolytes used in ZHCs often cause parasitic reactions during charging-discharging owing to free water molecules. Hydrated eutectic electrolytes (HEEs) that bind water molecules through solvation shells and hydrogen bonds can be applied at high temperatures and within a wide potential window. This study reports a novel bimetallic HEE (ZnK-HEE), consisting of zinc chloride, potassium chloride, ethylene glycol, and water, which enhances the capacity and electrochemical reaction kinetics of ZHCs. The bimetallic solvation shell in ZnK-HEE is studied by molecular dynamics and density functional theory, confirming its low step-by-step desolvation energy. A Zn//activated carbon ZHC in ZnK-HEE shows a high operating voltage of 2.1 V, along with an ultrahigh capacity of 326.9 mAh g-1 , power density of 2099.7 W kg-1 , and energy density of 343.2 Wh kg-1 at 100°C. The reaction mechanisms of charging-discharging process are investigated by ex situ X-ray diffraction. This study reports a promising electrolyte for high-performance ZHCs, which exhibits high-temperature resistance and is operable within a wide potential window.