Small-Dipole-Molecule-Containing Electrolytes for High-Voltage Aqueous Rechargeable Batteries

Sub-nanopores enabling optimized ion storage performance of carbon cathodes for Zn-ion hybrid supercapacitors

Aqueous Zn-ion hybrid supercapacitors (ZHSs) are attracting significant attention as a promising electrochemical energy storage system. However, carbon cathodes of ZHSs exhibit unsatisfactory ion storage performance due to the large size of hydrated Zn-ions (e.g., [Zn(H2O)6]2+), which encumbers compact ion arrangement and rapid ion transport at the carbon-electrolyte interfaces. Herein, a porous carbon material (HMFC) with abundant sub-nanopores is synthesized to optimize the ion storage performance of the carbon cathode in ZHSs, in which the sub-nanopores effectively promote the dehydration of hydrated Zn-ions and thus optimize the ion storage performance of the carbon cathode in ZHSs. A novel strategy is proposed to study the dehydration behaviors of hydrated Zn-ions in carbon cathodes, including quantitatively determining the desolvation activation energy of hydrated Zn-ions and in-situ monitoring active water content at the carbon-electrolyte interface. The sub-nanopores-induced desolvation effect is verified, and its coupling with large specific surface area and hierarchically porous structure endows the HMFC cathode with improved electrochemical performance, including a 53 % capacity increase compared to the carbon cathode counterpart without sub-nanopores, fast charge/discharge ability that can output 46.0 Wh/kg energy within only 4.4 s, and 98.2 % capacity retention over 20,000 charge/discharge cycles. This work provides new insights into the rational design of porous carbon cathode materials toward high-performance ZHSs.

Recent advances in zinc-ion dehydration strategies for optimized Zn-metal batteries

Aqueous Zn-metal batteries have attracted increasing interest for large-scale energy storage owing to their outstanding merits in terms of safety, cost and production. However, they constantly suffer from inadequate energy density and poor cycling stability due to the presence of zinc ions in the fully hydrated solvation state. Thus, designing the dehydrated solvation structure of zinc ions can effectively address the current drawbacks of aqueous Zn-metal batteries. In this case, considering the lack of studies focused on strategies for the dehydration of zinc ions, herein, we present a systematic and comprehensive review to deepen the understanding of zinc-ion solvation regulation. Two fundamental design principles of component regulation and pre-desolvation are summarized in terms of solvation environment formation and interfacial desolvation behavior. Subsequently, specific strategy based distinct principles are carefully discussed, including preparation methods, working mechanisms, analysis approaches and performance improvements. Finally, we present a general summary of the issues addressed using zinc-ion dehydration strategies, and four critical aspects to promote zinc-ion solvation regulation are presented as an outlook, involving updating (de)solvation theories, revealing interfacial evolution, enhancing analysis techniques and developing functional materials. We believe that this review will not only stimulate more creativity in optimizing aqueous electrolytes but also provide valuable insights into designing other battery systems.

Constructing Ionic Self-Concentrated Electrolyte via Introducing Montmorillonite Toward High-Performance Aqueous Zn-MnO2 Batteries

Aqueous zinc metal batteries are regarded as one of the most promising alternatives to lithium-ion batteries for large-scale energy storage due to the abundant zinc resources, high safety, and low cost. Herein, an ionic self-concentrated electrolyte (ISCE) is proposed to enable uniform Zn deposition and reversible reaction of MnO2 cathode. Benefitting from the compatibility of ISCE with electrodes and its adsorption on the electrode surface for guidance, the Zn/Zn symmetrical batteries exhibit the long-life cycle stability with more than 5000 and 1500 h at 0.2 and 5 mA cm-2, respectively. The Zn/MnO2 battery also exhibits a high capacity of 351 mA h g-1 at 0.1 A g-1 and can enable a stability over 2000 cycles at 1 A g-1. This work provides a new insight into electrolyte design for stable aqueous Zn-MnO2 battery.

Additives for Aqueous Zinc-Ion Batteries: Recent Progress, Mechanism Analysis, and Future Perspectives

Aqueous zinc-ion batteries (ZIBs) stand out as a promising next-generation electrochemical energy storage technology, offering notable advantages such as high specific capacity, enhanced safety, and cost-effectiveness. However, the application of aqueous electrolytes introduces challenges: Zn dendrite formation and parasitic reactions at the anode, as well as dissolution, electrostatic interaction, and by-product formation at the cathode. In addressing these electrode-centric problems, additive engineering has emerged as an effective strategy. This review delves into the latest advancements in electrolyte additives for ZIBs, emphasizing their role in resolving the existing issues. Key focus areas include improving morphology and reducing side reactions during battery cycling using synergistic effects of modulating anode interface regulation, zinc facet control, and restructuring of hydrogen bonds and solvation sheaths. Special attention is given to the efficacy of amino acids and zwitterions due to their multifunction to improve the cycling performance of batteries concerning cycle stability and lifespan. Additionally, the recent additive advancements are studied for low-temperature and extreme weather applications meticulously. This review concludes with a holistic look at the future of additive engineering, underscoring its critical role in advancing ZIB performance amidst the complexities and challenges of electrolyte additives.

Erythritol as a Saccharide Multifunctional Electrolyte Additive for Highly Reversible Zinc Anode

Dendrite formation and water-triggered side reactions on the surface of Zn metal anodes severely restrict the commercial viability of aqueous zinc-ion batteries (AZIBs). In this work, we introduce erythritol (Et) as an electrolyte additive to enhance the reversibility of zinc anodes, given its cost-effectiveness, mature technology, and extensive utilization in various domains such as food, medicine, and other industries. By combining multiscale theoretical simulation and experimental characterization, it was demonstrated that Et molecules can partially replace the coordination H2O molecules to reshape the Zn2+ solvation sheath and destroy the hydrogen bond network of the aqueous electrolyte. More importantly, Et molecules tend to adsorb on the zinc anode surface, simultaneously inhibit water-triggered side reactions by isolating water and promote uniform and dense deposition by accelerating the Zn2+ diffusion and regulating the nucleation size of the Zn grain. Thanks to this synergistic mechanism, the Zn anode can achieve a cycle life of more than 3900 h at 1 mA cm-2 and an average Coulombic efficiency of 99.77%. Coupling with δ-MnO2 cathodes, the full battery delivers a high specific capacity of 228.1 mAh g-1 with a capacity retention of 76% over 1000 cycles at 1 A g-1.

Employing a chelating agent as electrolyte additive with synergistic effects yields highly reversible zinc metal anodes

Aqueous zinc ion batteries (AZIBs) have attracted sustained attention owing to their intrinsic safety and low cost. Unfortunately, the dendrite growth and parasitic side reactions of metallic zinc anodes severely degrade the cycling stability of the batteries and limit the practical application of AZIBs. In this work, calcium gluconate (CG), a chelating agent, as a novel electrolyte additive was introduced to tackle the thorny issue of zinc anodes in a 2 M ZnSO4 electrolyte by the synergistic effects of gluconate (GA-) anions and Ca2+ cations. Experimental characterization and computational simulations confirmed that the incorporation of GA- can not only mitigate the precipitation of Ca2+ ions, but also affect the primary solvation shell (PSS) of Zn2+ and modulate the electrode/electrolyte interfacial reaction, thereby inhibiting side reactions. Besides, trace amounts of Ca2+ cations can preferentially adsorb on the surface of the zinc anode tip, forming an electrostatic shielding shell that guides the uniform deposition of zinc ions. The Zn//Zn symmetric cells achieved a remarkably prolonged cycling lifespan ranging from 174 h to 3745 h at 6.37 mA cm-2 and 2.88 mA h cm-2 with an ultrahigh cumulative plating capacity (CPC) of about 11 900 mA h cm-2. Even at a higher current density of 5 mA cm-2 and an areal specific capacity of 5 mA h cm-2, Zn//Zn cells with the CG additive cycled for 248 h, about 5 times better than that without the CG additive. These results pave the way for the exploitation of new electrolyte additives with synergistic effects in AZIBs.

Unlocking the Effect of Chain Length and Terminal Group on Ethylene Glycol Ether Family Toward Advanced Aqueous Electrolytes

Constructing high-performance hybrid electrolyte is important to advanced aqueous electrochemical energy storage devices. However, due to the lack of in-depth understanding of how the molecule structures of cosolvent additives influence the properties of electrolytes significantly impeded the development of hybrid electrolytes. Herein, a series of hybrid electrolytes are prepared by using ethylene glycol ether with different chain lengths and terminal groups as additives. The optimized 2 m LiTFSI-90%DDm hybrid electrolyte prepared from diethylene glycol dimethyl ether (DDm) molecule showcases excellent comprehensive performance and significantly enhances the operating voltage of supercapacitors (SCs) to 2.5 V by suppressing the activity of water. Moreover, the SC with 2 m LiTFSI-90%DDm hybrid electrolyte supplies a long-term cycling life of 50 000 cycles at 1 A g-1 with 92.3% capacitance retention as well as excellent low temperature (-40 ºC) cycling performance (10 000 times at 0.2 A g-1). Universally, Zn//polyaniline full cell with 2 m Zn(OTf)2-90%DDm electrolyte manifests outstanding cycling performance in terms of 77.9% capacity retention after 2,000 cycles and a dendrite-free Zn anode. This work inspires new thinking of developing advanced hybrid electrolytes by cosolvent molecule design toward high-performance energy storage devices.

A 2.4 V Aqueous Zinc-Ion Battery Enabled by the Photoelectrochemical Effect of a Modified BiOI Photocathode: Shattering the Shackle of the Electrochemical Window of an Aqueous Electrolyte

Aqueous zinc-ion batteries emerge as a promising energy storage system with merits of high security, abundance, and being environmentally benign. But the low operating voltages of aqueous electrolytes restrict their energy densities. Previous reports have mostly focused on modifying the electrolytes to enlarge the operating voltages of aqueous zinc-ion batteries. However, either extra-expensive salts or potential safety hazards of organic additives are considered to be adverse for practical large-scale applications. Here, a proof-of-concept to enlarge the operating voltage of an aqueous zinc-ion battery by incorporating a well-designed semiconductor photocathode is proposed, which produces a photovoltage (Vph) across the semiconductor/liquid junction (SCLJ) interface to elevate the output voltage of zinc-ion battery under irradiation. The operating voltage of an aqueous zinc-ion battery can be markedly raised from 1.78 (thermodynamic limit) to 2.4 V when a BiOI nanoflake array photocathode with good surface modification is introduced, achieving a round-trip efficiency of 114.3% and a 34.8% increase of energy density compared to the theoretical value. The successive ionic layer adsorption and reaction modified surface effectively passivates surface trap defects of the BiOI photocathode and thus enlarges its Vph from 60 to 240 mV under irradiation. This study provides a design to enlarge the output voltages of aqueous zinc-ion batteries and other energy storage systems, providing insight into widening the voltage window, which is that the operating voltages are determined by photocathode under irradiation and not restricted by the electrochemical stability window of dilute aqueous electrolytes.

Tuning the Microenvironment of Water Confined in Ti3C2Tx MXene by Cation Intercalation

The local microenvironment has recently been found to play a major role in the electrocatalytic activity of nanomaterials. Modulating the microenvironment by adding alkali metal cations into the electrolyte can be used to either suppress hydrogen or oxygen evolution, thereby extending the electrochemical window of energy storage systems, or to tune the selectivity of electrocatalysts. MXenes are a large family of two-dimensional transition metal carbides, nitrides, and carbonitrides that have shown potential for use in electrochemical energy storage applications. Due to their negatively charged surfaces, MXenes can accommodate cations and water molecules between the layers. Nevertheless, the nature of the aqueous microenvironment in the MXene interlayer space is poorly understood. Here, we apply Fourier transform infrared spectroscopy (FTIR) to probe the hydrogen bonding of intercalated water in Ti3C2Tx as a function of intercalated cation and relative humidity. Substantial changes in the FTIR spectra after cation exchange demonstrate that the hydrogen bonding of water molecules confined between the MXene layers is strongly cation-dependent. Furthermore, the IR absorbance of the confined water correlates with resistivity estimated by 4-point probe measurements and interlayer distance calculated from XRD patterns. This work demonstrates that cation intercalation strongly modulates the confined microenvironment, which can be used to tune the activity or selectivity of electrochemical reactions in the interlayer space of MXenes in the future.

Electrolyte Additives for Stable Zn Anodes

Zn-ion batteries are regarded as the most promising batteries for next-generation, large-scale energy storage because of their low cost, high safety, and eco-friendly nature. The use of aqueous electrolytes results in poor reversibility and leads to many challenges related to the Zn anode. Electrolyte additives can effectively address many such challenges, including dendrite growth and corrosion. This review provides a comprehensive introduction to the major challenges in and current strategies used for Zn anode protection. In particular, an in-depth and fundamental understanding is provided of the various functions of electrolyte additives, including electrostatic shielding, adsorption, in situ solid electrolyte interphase formation, enhancing water stability, and surface texture regulation. Potential future research directions for electrolyte additives used in aqueous Zn-ion batteries are also discussed.

A Bio-Inspired Trehalose Additive for Reversible Zinc Anodes with Improved Stability and Kinetics

The moderate reversibility of Zn anodes, as a long-standing challenge in aqueous zinc-ion batteries, promotes the exploration of suitable electrolyte additives continuously. It is crucial to establish the absolute predominance of smooth deposition within multiple interfacial reactions for stable zinc anodes, including suppressing side parasitic reactions and facilitating Zn plating process. Trehalose catches our attention due to the reported mechanisms in sustaining biological stabilization. In this work, the inter-disciplinary application of trehalose is reported in the electrolyte modification for the first time. The pivotal roles of trehalose in suppressed hydrogen evolution and accelerated Zn deposition have been investigated based on the principles of thermodynamics as well as reaction kinetics. The electrodeposit changes from random accumulation of flakes to dense bulk with (002)-plane exposure due to the unlocked crystal-face oriented deposition with trehalose addition. As a result, the highly reversible Zn anode is obtained, exhibiting a high average CE of 99.8 % in the Zn/Cu cell and stable cycling over 1500 h under 9.0 % depth of discharge in the Zn symmetric cell. The designing principles and mechanism analysis in this study could serve as a source of inspiration in exploring novel additives for advanced Zn anodes.

Next-generation magnesium-ion batteries: The quasi-solid-state approach to multivalent metal ion storage

Mg-ion batteries offer a safe, low-cost, and high-energy density alternative to current Li-ion batteries. However, nonaqueous Mg-ion batteries struggle with poor ionic conductivity, while aqueous batteries face a narrow electrochemical window. Our group previously developed a water-in-salt battery with an operating voltage above 2 V yet still lower than its nonaqueous counterpart because of the dominance of proton over Mg-ion insertion in the cathode. We designed a quasi-solid-state magnesium-ion battery (QSMB) that confines the hydrogen bond network for true multivalent metal ion storage. The QSMB demonstrates an energy density of 264 W·hour kg-1, nearly five times higher than aqueous Mg-ion batteries and a voltage plateau (2.6 to 2.0 V), outperforming other Mg-ion batteries. In addition, it retains 90% of its capacity after 900 cycles at subzero temperatures (-22°C). The QSMB leverages the advantages of aqueous and nonaqueous systems, offering an innovative approach to designing high-performing Mg-ion batteries and other multivalent metal ion batteries.

In Situ Raman Study of Voltage Tolerance Up to 2.2 V of Ionic Liquid Analogue Supercapacitor Electrolytes Immune to Water Adsorption Conferred by Amphoteric Imidazole Additives

Ionic liquid analogues (ILAs) are promising electrolytes for supercapacitors due to their low cost and considerable voltage (>2.0 V). However, the voltage is <1.1 V for water-adsorbed ILAs. Herein for the first time, an amphoteric imidazole (IMZ) additive is reported to address this concern by reconfiguring the solvent shell of ILAs. Addition of only 2 wt % IMZ increases the voltage from 1.1 to 2.2 V, with an increase in capacitance from 178 to 211 F g^-1 and an increase in energy density from 6.8 to 32.6 Wh kg^-1. In situ Raman reveals that the strong H-bonds formed by IMZ with completive ligands 1,3-propanediol and water induce a reversal of the polarity of the solvent shells, suppressing absorbed water electrochemical activity and thus increasing the voltage. This study solves the problem of low voltage for water-adsorbed ILAs and reduces the equipment cost of ILA-based supercapacitor assembly (e.g., assembly in air without a glovebox).

Dilute Hybrid Electrolyte for Low-Temperature Aqueous Sodium-Ion Batteries

A hybrid electrolyte based on low-concentration sodium nitrate with glycerol as an additive was proposed for aqueous sodium-ion batteries (ASIBs) towards low-temperature performance. Based on this dilute hybrid electrolyte and configured by bimetallic Prussian blue analogue (Ni₂ ZnHCF) cathode and 3,4,9,10-perylenetetracarboxylic diimide (PTCDI) anode, the full cell demonstrated surprising cycle performance with a specific capacity of 60 mAh g^-1 (>800 cycles) and achieved prominent performance at low temperature. Glycerol effectively expanded the electrochemical stability window of the hybrid electrolyte to 2.7 V from formation of strong hydrogen bonds with water molecules and realized the operation of the cell at low temperature, delivering a stable reversible capacity of 40 mAh g^-1 at -10 °C. The hybrid electrolyte of glycerol-water provides a new alternative in development of low-cost, long-lifespan, and low-temperature ASIBs and other aqueous battery systems.

Desolvation Synergy of Multiple H/Li-Bonds on an Iron-Dextran-Based Catalyst Stimulates Lithium-Sulfur Cascade Catalysis

Traditional lithium-sulfur battery catalysts are still facing substantial challenges in solving sulfur redox reactions, which involve multistep electron transfer and multiphase transformations. Here, inspired by the combination of iron dextran (INFeD) and ascorbic acid (VC) as a blood tonic for the treatment of anemia, a highly efficient VC@INFeD catalyst is developed in the sulfur cathode, accomplishing the desolvation and enrichment of high-concentration solvated lithium polysulfides at the cathode/electrolyte interface with the assistance of multiple H/Li-bonds and resolving subsequent sulfur transformations through gradient catalysis sites where the INFeD promotes long-chain lithium polysulfide conversions and VC accelerates short-chain lithium polysulfide conversions. Comprehensive characterizations reveal that the VC@INFeD can substantially reduce the energy barrier of each sulfur redox step, inhibit shuttle effects, and endow the lithium-sulfur battery with high sulfur utilization and superior cycling stability even under a high sulfur loading (5.2 mg cm^-2 ) and lean electrolyte (electrolyte/sulfur ratio, ≈7 µL mg^-1 ) condition.

Integrated Construction Improving Electrochemical Performance of Stretchable Supercapacitors Based on Ant-Nest Amphiphilic Gel Electrolytes

Aqueous integrated stretchable supercapacitors (ISSCs) have attracted extensive attention due to the intrinsic safety in future wearable electronics. However, aqueous ISSCs usually suffer from low energy density and poor dynamic deformation stability owing to the conventional hydrogel electrolytes' narrow electrochemical stability window (ESW) and dissatisfied interface bonding. Herein, an ant-nest amphiphilic polyurethane hydro/organogel electrolyte (sAPUGE) with a wide ESW (≈2.2 V) and superb self-adhesion is prepared by electrospinning, which interacts with carbon-based stretchable electrodes for the construction of flame-retardant PU-based sAPUGE-ISSC. Benefitting from the synergistic effect of chemical bonding and mechanical meshing between the electrode and gel electrolyte interface, as-assembled sAPUGE-ISSC delivers a high energy density of 13.7 mWh cm^-3 (at a power density of 0.126 W cm^-3 ) and outstanding dynamic deformation stability (98.3% capacitance retention after 500 stretching cycles under 100% strain). This unique hydro/organogel electrolyte provides a pathway toward the next generation of wearable energy products in modern electronics.

In Situ Construction of Protective Films on Zn Metal Anodes via Natural Protein Additives Enabling High-Performance Zinc Ion Batteries

The strong activity of water molecules causes a series of parasitic side reactions on Zn anodes in the aqueous electrolytes. Herein, we introduce silk fibroin (SF) as a multifunctional electrolyte additive for aqueous zinc-ion (Zn-ion) batteries. The secondary structure transformation of SF molecules from α-helices to random coils in the aqueous electrolytes allows them to break the hydrogen bond network among free water molecules and participate in Zn²⁺ ion solvation structure. The SF molecules released from the [Zn(H₂O)₄(SF)]²⁺ solvation sheath appear to be gradually adsorbed on the surface of Zn anodes and in situ form a hydrostable and self-healable protective film. This SF-based protective film not only shows strong Zn²⁺ ion affinity to promote homogeneous Zn deposition but also has good insulating behavior to suppress parasitic reactions. Benefiting from these multifunctional advantages, the cycle life of the Zn||Zn symmetric cells reaches over 1600 h in SF-containing ZnSO₄ electrolytes. In addition, by adopting a potassium vanadate cathode, the full cell shows excellent cycling stability for 1000 cycles at 3 A g^-1. The in situ construction of a protective film on the Zn anode from natural protein molecules provides an effective strategy to achieve high-performance Zn metal anodes for Zn-ion batteries.

Anion-Reinforced Solvation for a Gradient Inorganic-Rich Interphase Enables High-Rate and Stable Sodium Batteries

Metallic Na is a promising anode for rechargeable batteries, however, it is plagued by an unstable solid electrolyte interphase (SEI) and Na dendrites. Herein, a robust anion-derived SEI is constructed on Na anode in a high-concentration 1,2-dimethoxyethane (DME) based electrolyte with a cosolvent hydrofluoroether, which effectively restrains Na dendrite growth. The hydrofluoroether can tune the solvation configuration of the electrolyte from three-dimensional network aggregates to solvent-cation-anion clusters, enabling more anions to enter and reinforce the inner solvation sheath and their stepwise decomposition. The gradient inorganic-rich SEI leads to a reduced energy barrier of Na⁺ migration and enhanced interfacial kinetics. These render the Na||Na₃ V₂ (PO₄ )₃ battery with an excellent rate capability of 79.9 mAh g^-1 at 24 C and a high capacity retention of 94.2 % after 6000 cycles at 2 C. This highlights the modulation of the electrode-electrolyte interphase chemistry for advanced batteries.

Aqueous Electrolytes with Hydrophobic Organic Cosolvents for Stabilizing Zinc Metal Anodes

Rechargeable aqueous zinc (Zn) batteries are promising for large-energy storage because of their low cost, high safety, and environmental compatibility, but their implementation is hindered by the severe irreversibility of Zn metal anodes as exemplified by water-induced side reactions (H₂ evolution and Zn corrosion) and dendrite growth. Here, we find that the introduction of a hydrophobic carbonate cosolvent into a dilute aqueous electrolyte exhibits a much stronger ability to address the reversible issues facing Zn anodes than that with hydrophilic ones. Among the typical carbonates (ethylene carbonate, propylene carbonate, dimethyl carbonate, and diethyl carbonate (DEC)), DEC as the most hydrophobic additive enables the strongest breaking of water's H-bond network and replaces the solvating H₂O in a Zn²⁺-solvation sheath, which significantly reduces the water activity and its decomposition. Additionally, DEC molecules preferentially adsorb onto the Zn surface to create an H₂O-poor electrical double layer and render a dendrite-free Zn²⁺-plating behavior. The formulated hybrid 2 m Zn(OTf)₂ + 7 m DEC electrolyte endows the Zn electrode with an ability to achieve high cycling stability (over 3500 h at 5 mA cm^-2 with 2.5 mA h cm^-2) and supports the stable operation of Zn||V₂O₅·nH₂O full battery. This efficient strategy with hydrophobic cosolvent suggests a promising direction for designing aqueous battery chemistries.

Hydrogen-Bond Disrupting Electrolytes for Fast and Stable Proton Batteries

Rechargeable aqueous proton batteries are promising competitors for the next generation of energy storage systems with the fast diffusion kinetics and wide availability of protons. However, poor cycling stability is a big challenge for proton batteries due to the attachment of water molecules to the electrode surface in acid electrolytes. Here, a hydrogen-bond disrupting electrolyte strategy to boost proton battery stability via simultaneously tuning the hydronium ion solvation sheath in the electrolyte and the electrode interface is reported. By mixing cryoprotectants such as glycerol with acids, hydrogen bonds involving water molecules are disrupted leading to a modified hydronium ion solvation sheaths and minimized water activity. Concomitantly, glycerol absorbs on the electrode surface and acts to protect the electrode surface from water. Fast and stable proton storage with high rate capability and long cycle life is thus achieved, even at temperatures as low as -50 °C. This electrolyte strategy may be universal and is likely to pave the way toward highly stable aqueous energy storage systems.

Applying Classical, Ab Initio, and Machine-Learning Molecular Dynamics Simulations to the Liquid Electrolyte for Rechargeable Batteries

Rechargeable batteries have become indispensable implements in our daily life and are considered a promising technology to construct sustainable energy systems in the future. The liquid electrolyte is one of the most important parts of a battery and is extremely critical in stabilizing the electrode-electrolyte interfaces and constructing safe and long-life-span batteries. Tremendous efforts have been devoted to developing new electrolyte solvents, salts, additives, and recipes, where molecular dynamics (MD) simulations play an increasingly important role in exploring electrolyte structures, physicochemical properties such as ionic conductivity, and interfacial reaction mechanisms. This review affords an overview of applying MD simulations in the study of liquid electrolytes for rechargeable batteries. First, the fundamentals and recent theoretical progress in three-class MD simulations are summarized, including classical, ab initio, and machine-learning MD simulations (section 2). Next, the application of MD simulations to the exploration of liquid electrolytes, including probing bulk and interfacial structures (section 3), deriving macroscopic properties such as ionic conductivity and dielectric constant of electrolytes (section 4), and revealing the electrode-electrolyte interfacial reaction mechanisms (section 5), are sequentially presented. Finally, a general conclusion and an insightful perspective on current challenges and future directions in applying MD simulations to liquid electrolytes are provided. Machine-learning technologies are highlighted to figure out these challenging issues facing MD simulations and electrolyte research and promote the rational design of advanced electrolytes for next-generation rechargeable batteries.

Ferroelectric benzimidazole additive-induced interfacial water confinement for stable 2.2V supercapacitor electrolytes exposed to air

Deep eutectic solvents (DES) are known as low-cost and environmentally friendly electrolytes for supercapacitors. However, because DES is particularly vulnerable to moisture adsorption in the air, the voltage window (<...