Comprehensive Understandings of Hydrogen Bond Chemistry in Aqueous Batteries

Mitigating crosstalk through water deactivation to achieve advanced Zn-ion batteries with superior temperature adaptability

Zn||V2O5 full cell exhibit excellent low-temperature performance in Zn(ClO4)2 based electrolytes due to the strong hydrogen bond breaking effect. However, the crosstalk effect between the V2O5 cathode and Zn anode at room temperature leads to continuous side reactions, highly limiting their practical application. Herein, a water deactivation strategy by introducing methanol additive has been proposed and its effect mechanism on the crosstalk has been explored. It is found that the methanol additive is conducive to build a water-poor solvation structure and reduce the activity of free water, inhibiting the corrosion and improving the cycle stability of Zn anode. In addition, methanol additive triggers the reversible cycling of inert Zn3(OH)2(V2O7)(H2O)2, and suppress its deposition on Zn anode, then breaking the electrochemical crosstalk problem of the Zn||V2O5 system. As expected, the Zn||V2O5 full cell at the designed electrolyte demonstrates superior performance at room and low temperature, delivering a high specific capacity of 300 mAh g-1 at 25 °C, and operating stably for 7500 (>2000 h) cycles without capacity loss at -20 °C, which are superior to most reported works. This work might provide new ideas for addressing electrochemical crosstalk and constructing advanced batteries with superior temperature adaptability.

Interlayer engineering-induced charge redistribution in Bi2Te3 toward efficient Zn2+ and NH4 + storage

Bismuth-based materials show promise for aqueous energy storage systems due to their unique layered structures and high storage capacity. Some bismuth-based materials have been applied to store Zn2+ or NH4 +, indicating that one bismuth-based compound may be innovatively used in both zinc-ion and ammonium-ion batteries (ZIBs and AIBs). Herein, we successfully design a poly(3,4-ethylenedioxythiophene) (PEDOT) coated and embedded Bi2Te3 (Bi2Te3@PEDOT). Theoretical calculations and experimental studies demonstrate that the PEDOT coating and its intercalation into the interlayer enhance the structural stability of Bi2Te3 and significantly improve the storage capacities for Zn2+ and NH4 +. The PEDOT intercalation results in an increased interlayer spacing and a charge redistribution in the interlayer, facilitating charge transfer. Additionally, the insertion-type mechanism of Zn2+ and NH4 + in Bi2Te3@PEDOT is revealed through ex situ tests. The optimized electrode (5 mg cm-2) exhibits high discharge capacities of 385 mA h g-1 in ZIBs and 235 mA h g-1 in AIBs at 0.2 A g-1 and long-term cycle stability. Bi2Te3@PEDOT performs robustly even at a high mass loading of 10 mg cm-2. Bi2Te3@PEDOT//MnO2 (ZIBs) and Bi2Te3@PEDOT//ZnMn2O4 (AIBs) full cells offer high reversible capacities. This work provides a reference for designing bifunctional energy storage materials.

Dynamic Short Hydrogen-Bonding Network Enhancing Hydrophilicity in Biomimetic Membranes with Artificial Water Channels for Efficient Removal of Dyes and Salts

The development of an integrated biomimetic membrane capable of rejecting both dyes and salts in a single step, while sustaining stable water permeation, presents a promising solution for textile wastewater treatment. Herein, we report a novel integrated biomimetic membrane integrating an I-quartet artificial water channel (AWC) with sulfonic acid-modified polyamide (PA-SO3H), which can stably reject both dyes and inorganic salts. The I-quartet channels (2.68 Å), formed via self-assembly of alkyl-ureido-ethyl-imidazole (HC8) molecules, facilitate selective water transport and rejection of both dyes and inorganic salts. Concurrently, the sulfonic acid groups (-SO3H) could grab water molecules, forming dynamic short hydrogen-bonding network (O-H⋅⋅⋅O). These hydrogen bonds not only serve as jumping force, lowering the energy barrier for water transport through the alternating hydrophilic-hydrophobic matrix, but also act as an effective antifouling barrier, significantly reducing membrane fouling. The optimal HC83.0-PA-SO3H membrane exhibits a water permeance of 13.4 L m-2 h-1 MPa-1, approximately 2.7-fold higher than that of the pristine PA membrane, and both high dyes and salts rejection efficiency. Moreover, the membrane sustains stable antifouling characteristics throughout a 19-day endurance test. This innovative membrane design provides a promising solution for the efficient separation of both dyes and inorganic salts in textile wastewater treatment.

Polymer additives in liquid electrolytes for advanced lithium batteries

Compared to traditional energy storage devices, lithium-ion batteries (LIBs) have the advantages of high energy density, good cycling performance, and low self-discharge rate. Therefore, LIBs have been widely used as the main energy storage devices in various industries. As the blood of the battery, the electrolyte plays a key role in ion transport, formation of the interface layer, protection of electrode materials, etc. The commonly investigated electrolytes include liquid electrolytes, gel electrolytes, and solid or quasi-solid electrolytes. Liquid electrolytes have higher ionic conductivity, which is more conducive to the transport of lithium ions. Therefore, batteries based on liquid electrolytes often exhibit better electrochemical performance. In a liquid electrolyte, the additive is also an indispensable component to ensure the high efficiency of the electrolyte, which plays an important role in regulating the solvation structure of lithium ions, the formation of the solid-electrolyte interface layer, improving the safety performance of batteries, and maintaining operability under extreme conditions (such as low temperature). Unlike previous reviews that focused on small molecule additives, this review herein mainly reviews the application of polymer additives in liquid lithium batteries. Firstly, the functional mechanisms of different types of additives in liquid electrolytesfor lithium batteries are outlined and the advantages and disadvantages of different types of additives are summarized. Then, the research progress of polymers as additives in liquid lithium batteries in recent years is discussed in detail. According to the role of additives, the involved polymer additives are divided into five categories: molecular crowding agents, film-forming agents, HF scavengers, antifreeze agents, and flame retardants. A detailed explanation of the mechanisms related to the efficacy of polymers as additives is also provided. Finally, we present some perspectives on the limitations and future development trends of polymers as additives in liquid lithium batteries and other devices.

A Highly Reversible Aqueous Sulfur-Dual-Halogen Battery Enabled by a Water-in-Bisalt Electrolyte

The chlorine-based redox reaction applied in aqueous rechargeable batteries (ARBs) has attracted extensive attention owing to the high theoretical capacity and redox potential. However, it generally suffers from low reversibility and poor Coulombic efficiency due to the evolution of toxic Cl2 gas and the decomposition of aqueous electrolytes. Herein, an aqueous sulfur-dual halogen chemistry is demonstrated by employing highly-concentrated water-in-bisalt (WiBS) electrolyte, sulfur anode, and iodine composite electrodes. The freestanding iodine/carbon cloth cathode and Cl--containing WiBS electrolyte not only enable the continuous I+/I0 reaction by forming [IClx]1-x interhalogens but also achieve the oxidation of Cl- in [IClx]1-x at higher redox potential and immobilize Cl0 species via I+─Cl0 chemical bonds. Therefore, the as-assembled aqueous sulfur-dual halogen batteries (ASHBs) based on the dual-halogen conversion on the cathode and the S/Sx 2- redox reaction on the anode deliver a high energy density of 304 Wh kg-1 with an average output voltage of 1.32 V. These key findings open an avenue for the development of low-cost and high-performance ARBs for energy storage applications.

Targeted Docking of Localized Hydrogen Bond for Efficient and Reversible Zinc-Ion Batteries

Hydrogen bond (HB) chemistry, a pivotal feature of aqueous zinc-ion batteries, modulates electrochemical processes through weak electrostatic interactions among water molecules. However, significant challenges persist, including sluggish desolvation kinetics and inescapable parasitic reactions at the electrolyte-electrode interface, associated with high water activity and strong Zn2+-solvent coordination. Herein, a targeted localized HB docking mechanism is activated by the polyhydroxy hexitol-based electrolyte, optimizing Zn2+ solvation structures via dipole interaction and reconstructing interfacial HB networks through preferential parallel adsorption. By combining in situ spectroscopic characterizations with theoretical calculations, we elucidate the dynamic evolution of localized HB networks, which enhance Zn2+ deposition kinetics and homogeneity, suppress water-induced side reactions, and mitigate vanadium framework collapse. Our findings support that the targeted HB docking strategy facilitates fast interfacial ion transport kinetics and enables high reversibility, with a substantially prolonged symmetric cell lifespan exceeding 5000 h. This work markedly advances the efficient and reversible zinc-based batteries.

Building Powerful Zinc-Ion Hybrid Capacitors by an Energy Drink-Inspired Strategy

Numerous modification strategies have been proposed to enhance the performance of the Zn anode and carbon cathode in aqueous zinc-ion hybrid capacitors (ZIHCs). However, one efficient strategy to modify both the anode and cathode is still lacking. Herein, taurine (Tau), the key ingredient of energy drinks, is used as the electrolyte additive and carbon precursor for ZIHCs simultaneously. As the electrolyte additive, Tau achieves the preferential growth of Zn (002) plane by preferentially adsorbing on other crystal planes. Moreover, Tau accelerates Zn2+ transference kinetics by regulating the Zn2+ solvation structure and constructs a functional solid electrolyte interphase layer, enabling suppressed hydrogen evolution, inhibited corrosion reaction, and dendrite-free deposition. The Zn//Zn cells using the Tau-modified·ZnSO4 electrolyte (Tau-ZSO) can stably work for 1000 h at 76.95% depth of discharge at room temperature and 5200 h at -10 °C. Meanwhile, the taurine-derived carbon (Tau-C) exhibits N, S heteroatom doping, hierarchical porous structure, and high specific surface area, which contributes to a high cathode capacity. By using the Tau-C cathode, limited Zn anode (10 µm), and the Tau-ZSO electrolyte, the assembled ZIHCs demonstrate reduced polarization and high discharge capacities (119.4 mA h g-1 under 3 A g-1 at room temperature and 80.0 mA h g-1 under 1 A g-1 at -10 °C) with high energy density of 101.1 Wh kg-1 and long lifetime (operating stably over 2000 cycles).

Water-Deficient Interface Induced via Hydrated Eutectic Electrolyte with Restrictive Water to Achieve High-Performance Aqueous Zinc Metal Batteries

The development of aqueous zinc metal batteries (AZMBs) is hampered by dendrites and side reactions induced by reactive H2O. In this study, a hydrated eutectic electrolyte with restrictive water consisting of zinc trifluoromethanesulfonate (Zn(OTf)2), 1,3-propanediol (PDO), and water is developed to improve the stability of the anode/electrolyte interface in AZMBs via the formation of a water-deficient interface. Additionally, PDO participates in the Zn2+ solvation structure and inhibits the movement of water molecules. PDO also preferentially adsorbs along the Zn (100) plane, thereby inducing the formation of the organic/inorganic SEI layer that enables the cycle life of a Zn//Zn symmetric cell to reach 3000 h at 1 mA cm-2 and 1 mAh cm-2. Further, interfacial modulation by the eutectic electrolyte improves the cycling stability of Zn//V2O5 and Zn//VO2 cells. Particularly, the specific capacity of a Zn//V2O5 cell with the eutectic electrolyte is 1.7 times that of a cell with the 2M Zn(OTf)2 electrolyte, with a capacity retention of 93% after 100 cycles at 0.5 A g-1. This study provides a new perspective on the electrolyte modification strategies for AZMBs, highlighting the potential of PDO-8 electrolyte in developing aqueous energy storage devices with excellent cycling stability.

Active Water Optimization in Different Electrolyte Systems for Stable Zinc Anodes

Zinc (Zn) metal, with abundant resources, intrinsic safety, and environmental benignity, presents an attractive prospect as a novel electrode material. However, many substantial challenges remain in realizing the widespread application of aqueous Zn-ion batteries (AZIBs) technologies. These encompass significant material corrosion challenges (This can lead to battery failure in an unloaded state.), hydrogen evolution reactions, pronounced dendrite growth at the anode interface, and a constrained electrochemical stability window. Consequently, these factors contribute to diminished battery lifespan and energy efficiency while restricting high-voltage performance. Although numerous reviews have addressed the potential of electrode and separator design to mitigate these issues to some extent, the inherent reactivity of water remains the fundamental source of these challenges, underscoring the necessity for precise regulation of active water molecules within the electrolyte. In this review, the failure mechanism of AZIBs (unloaded and in charge and discharge state) is analyzed, and the optimization strategy and working principle of water in the electrolyte are reviewed, aiming to provide insights for effectively controlling the corrosion process and hydrogen evolution reaction, further controlling dendrite formation, and expanding the range of electrochemical stability. Furthermore, it outlines the challenges to promote its practical application and future development pathways.

Hydrogen/Electron Amphiphilic Bi-Functional Water Molecular Inactivator-Assisted Interface Stabilization in Highly Reversible Zn Metal Batteries

Continuous hydrogen-bond-network in aqueous electrolytes can lead to uncontrollable hydrogen transfer, and combining the interfacial parasitic electron consumption cause the side reaction in aqueous zinc metal batteries (AZMBs). Herein, hydrogen/electron amphiphilic bi-functional 1,5-Pentanediol (PD) molecule was introduced to stabilize the electrode/electrolyte interface. Stronger proton affinity of -OH in PD can break bulk-H2O hydrogen-bond-network to inhibit the activity of water, and electron affinity can enhance electron acceptation capability, which ensures that PD is preferentially bound to electrode material over H2O. Besides, the participation of PD in the Zn2+ solvation structure reduces water content at the solid-liquid interface and promotes uniform deposition process by optimizing Zn2+ de-solvation energy. Accordingly, dense and vertical zinc texture based on intrinsic steric hindrance effect of PD and formed SEI protective layer to induce stable Zinc anode-electrolyte interface. Moreover, an organic-inorganic shielding water layer was formed at the cathode side to suppress vanadium dissolution in vanadium Oxide. Consequently, Zn//Zn symmetric cell could cycle for more than 5600 hours at 1 mAh cm-2@1 mA cm-2 (more than 250 hours at 50 °C). Besides, the VO2 and I2 cathode all achieved stable cycling performance and former pouch cell could reach average capacity of 0.13 Ah.

From Salt in Water, Water in Salt to Beyond

Traditional aqueous electrolytes have a limited electrochemical stability window due to the decomposition voltage of water (≈1.23 V). "Water-in-Salt" (WIS) electrolytes are developed, which expand the stability window of aqueous electrolytes from 1.23 to 3 V and sparked a global surge of research in aqueous batteries. This breakthrough revealed novel aspects of solvation structure, ion transport mechanisms, and interfacial properties in WIS electrolytes, marking the start of a new era in solution chemistry that extends beyond traditional dilute electrolytes and has implications across electrolyte research. In this review, the current mechanistic understanding of WIS electrolytes and their derivative designs, focusing on the construction of solvation structures is presented. The insights gained and limitations encountered in bulk solvation structure engineering is further discussed. Finally, future directions beyond WIS for advancing aqueous electrolyte design is proposed.

Breaking the Ice: Hofmeister Effect-Inspired Hydrogen Bond Network Reconstruction in Hydrogel Electrolytes for High-Performance Zinc-Ion Batteries

Gel electrolytes have emerged as a promising solution for enhancing the performance of zinc-ion batteries (ZIBs), particularly in flexible devices. However, they face challenges such as low-temperature inefficiency, constrained ionic conductivity, and poor mechanical strength. To address these issues, this study presents a novel PAMCD gel electrolyte with tunable freezing point and mechanical properties for ZIBs, blending the high ionic conductivity of polyacrylamide with the anion interaction capability of β-cyclodextrin. Leveraging the Hofmeister effect, the chaotropic anions of ClO4 - are integrated to weaken hydrogen bonds, enhancing the mechanical and anti-freezing properties. The chaotropic salt disrupts the hydrogen bond network within water molecules, increasing weaker bonds and forming contact ion pairs, while polyacrylamide chains bind water molecules, further destabilizing hydrogen bonds. These changes improve Zn2+ ion mobility, mechanical resilience, and reduce the freezing point, significantly boosting ZIB performance. Consequently, the Zn-Zn symmetric cells achieve remarkable lifespans over 5290 hours at 0.5 mA cm-2 and 1960 hours at 5 mA cm-2, and the Zn-polyaniline full batteries maintain a high capacity of 100.8 mAh g-1 at 2 A g-1, even at -40 °C, over 7600 cycles, showcasing superior cyclability and rate performance.

Synchronous Modulation of H-bond Interaction and Steric Hindrance via Bio-molecular Additive Screening in Zn Batteries

In addressing challenges such as side reaction and dendrite formation, electrolyte modification with bio-molecule sugar species has emerged as a promising avenue for Zn anode stabilization. Nevertheless, considering the structural variability of sugar, a comprehensive screening strategy is meaningful yet remains elusive. Herein, we report the usage of sugar additives as a representative of bio-molecules to develop a screening descriptor based on the modulation of the hydrogen bond component and electron transfer kinetics. It is found that xylo-oligosaccharide (Xos) with the highest H-bond acceptor ratio enables efficient water binding, affording stable Zn/electrolyte interphase to alleviate hydrogen evolution. Meanwhile, sluggish reduction originated from the steric hindrance of Xos contributes to optimized Zn deposition. With such a selected additive in hand, the Zn||ZnVO full cells demonstrate durable operation. This study is anticipated to provide a rational guidance in sugar additive selection for aqueous Zn batteries.

Effective Proton Conduction in Quasi-Solid Zinc-Manganese Batteries via Constructing Highly Connected Transfer Pathways

Elusive ion behaviors in aqueous electrolyte remain a challenge to break through the practicality of aqueous zinc-manganese batteries (AZMBs), a promising candidate for safe grid-scale energy storage systems. The proposed electrolyte strategies for this issue most ignore the prominent role of proton conduction, which greatly affects the operation stability of AZMBs. Here we report a water-poor quasi-solid electrolyte with efficient proton transfer pathways based on the large-space interlayer of montmorillonite and strong-hydration Pr3+ additive in AZMBs. Proton conduction is deeply understood in this quasi-solid electrolyte. Pr3+ additive not only dominates the proton conduction kinetics, but also regulates the reversible manganese interfacial deposition. As a result, the Cu@Zn||α-MnO2 cell could achieve a high specific capacity of 433 mAh g-1 at 0.4 mA cm-2 and an excellent stability up to 800 cycles with a capacity retention of 92.2 % at 0.8 mA cm-2 in such water-poor quasi-solid electrolyte for the first time. Ah-scale pouch cell with mass loading of 15.19 mg cm-2 sustains 100 cycles after initial activation, which is much better than its counterparts. Our work provides a new path for the development of zinc metal batteries with good sustainability and practicality.

Succinonitrile Electrolyte Additive for Stabilizing Aqueous Zinc Metal Batteries

The utilization of water electrolytes in zinc-ion batteries offers the advantages of enhanced safety, reduced cost, and improved environmental friendliness, rendering them an optimal choice for replacing lithium-ion batteries. Nevertheless, the conventional zinc sulfate electrolyte fails to meet stringent requirements. Therefore, developing electrolytes is crucial for addressing the low cycle life of zinc ions and suppressing the growth of zinc dendrites. So we proposed a strategy for engineering dilution of aqueous Zn(OTf)2 solution with succinonitrile (SN) network electrolytes. The introduction of SN also disrupts the original hydrogen bonding network within the system and mitigates issues related to side reactions. Additionally, the inclusion of SN additives significantly diminishes the reactivity of water molecules and smoothing zinc deposition to form favorable two-component Zn3N2/ZnF2 SEI. The results indicate that symmetric cells exhibit a remarkable cycling performance (877 h at current density and capacity of 1 mA cm-2 and 1 mAh cm-2, respectively). Furthermore, after 2000 cycles at a current density of 5 A g-1, the full battery demonstrates an impressive capacity of 151.2 mAh g-1. These results show that the electrolyte structure project provides a promising direction for the design of aqueous zinc-metal batteries, aiming to achieve high reversibility and long cycle life.

Synergistic effect of hydrogen-bond interaction and interface regulation for stable aqueous sodium-ion batteries

The narrow voltage window of aqueous electrolytes hinders the energy density of aqueous sodium-ion batteries (SIBs). Herein, a thermally and electrochemically stable hybrid electrolyte is developed with NaCF3SO3, 1,3-dioxolane (DOL), urea and H2O. The intermolecular interactions between DOL, urea and H2O regulate the hydrogen-bond network. Furthermore, the formation of an interfacial layer between the electrode and the electrolyte enables stable cycling of the manganese-based Prussian blue analogs (NaFeMnPBAs). As a result, a NaFeMnPBAs‖NaTi2(PO4)3 full cell is constructed and it exhibits high energy density and superior stability in the hybrid electrolyte.

Toward the Rechargeable Aqueous Zinc Ion Batteries with Improved Overall Performance: Electrolyte with Surface Adsorptive Additive

Aqueous zinc-ion batteries (AZIBs) with slightly acidic electrolytes process advantages such as high safety, competitive cost, and satisfactory electrochemical performance. However, the failure behaviors of both electrodes, regarding zinc dendrite growth, interfacial parasitic reactions, and the collapse of cathode materials hinder the practical application of ZIBs. To alleviate the issues of both anode and cathode at the same time, D-xylose (DX) is introduced to the electrolyte as a multifunctional additive. As a result, the side reaction of the anode is suppressed and the metallic deposition behavior is regulated due to the hydrogen bonding network reconstruction and preferential surface adsorption of DX; for the MnO2 cathode, the DX adsorption can help the interfacial charge transfer and increase the reactive sites. Benefiting from these merits, DX-optimized Zn//Zn battery displays reveal a prolonged lifespan of 6912 h and an ultra-high cumulative capacity of 17.28 Ah cm-2 at 5 mA cm-2. With the function of water reactivity suppression, the Coulombic efficiency reaches 99.91% at 2 mA cm-2; the Zn||MnO2 full batteries exhibit excellent cyclability over 2000 cycles at 5C with an increased capacity of 118.9 mAh g-1, indicating the dual functions to both of the electrodes for AZIBs.

Coordination and Hydrogen Bond Chemistry in Tungsten Oxide@Polyaniline Composite toward High-Capacity Aqueous Ammonium Storage

Aqueous ammonium ion batteries (AAIBs) have garnered significant attention due to their unique energy storage mechanism. However, their progress is hindered by the relatively low capacities of NH4 + host materials. Herein, the study proposes an electrodeposited tungsten oxide@polyaniline (WOx@PANI) composite electrode as a NH4 + host, which achieves an ultrahigh capacity of 280.3 mAh g-1 at 1 A g-1, surpassing the vast majority of previously reported NH4 + host materials. The synergistic interaction of coordination chemistry and hydrogen bond chemistry between the WOx and PANI enhances the charge storage capacity. Experimental results indicate that the strong interfacial coordination bonding (N: →W6+) effectively modulates the chemical environment of W atoms, enhances the protonation level of PANI, and thus consequently the conductivity and stability of the composites. Spectroscopy analysis further reveals a unique NH4 +/H+ co-insertion mechanism, in which the interfacial hydrogen bond network (N-H···O) accelerates proton involvement in the energy storage process and activates the Grotthuss hopping conduction of H+ between the hydrated tungsten oxide layers. This work opens a new avenue to achieving high-capacity NH4 + storage through interfacial chemistry interactions, overcoming the capacity limitations of NH4 + host materials for aqueous energy storage.

Zinc Chemistries of Hybrid Electrolytes in Zinc Metal Batteries: From Solvent Structure to Interfaces

Along with the booming research on zinc metal batteries (ZMBs) in recent years, operational issues originated from inferior interfacial reversibility have become inevitable. Presently, single-component electrolytes represented by aqueous solution, "water-in-salt," solid, eutectic, ionic liquids, hydrogel, or organic solvent system are hard to undertake independently the task of guiding the practical application of ZMBs due to their specific limitations. The hybrid electrolytes modulate microscopic interaction mode between Zn2+ and other ions/molecules, integrating vantage of respective electrolyte systems. They even demonstrate original Zn2+ mobility pattern or interfacial chemistries mechanism distinct from single-component electrolytes, providing considerable opportunities for solving electromigration and interfacial problems in ZMBs. Therefore, it is urgent to comprehensively summarize the zinc chemistries principles, characteristics, and applications of various hybrid electrolytes employed in ZMBs. This review begins with elucidating the chemical bonding mode of Zn2+ and interfacial physicochemical theory, and then systematically elaborates the microscopic solvent structure, Zn2+ migration forms, physicochemical properties, and the zinc chemistries mechanisms at the anode/cathode interfaces in each type of hybrid electrolytes. Among of which, the scotoma and amelioration strategies for the current hybrid electrolytes are actively exposited, expecting to provide referenceable insights for further progress of future high-quality ZMBs.

Strategically Modulating Proton Activity and Electric Double Layer Adsorption for Innovative All-Vanadium Aqueous Mn2+/Proton Hybrid Batteries

Aqueous Mn-ion batteries (MIBs) exhibit a promising development potential due to their cost-effectiveness, high safety, and potential for high energy density. However, the development of MIBs is hindered by the lack of electrode materials capable of storing Mn2+ ions due to acidic manganese salt electrolytes and large ion radius. Herein, the tunnel-type structure of monoclinic VO2 nanorods to effectively store Mn2+ ions via a reversible (de)insertion chemistry for the first time is reported. Utilizing exhaustive in situ/ex situ multi-scale characterization techniques and theoretical calculations, the co-insertion process of Mn2+/proton is revealed, elucidating the capacity decay mechanism wherein high proton activity leads to irreversible dissolution loss of vanadium species. Further, the Grotthuss transfer mechanism of protons is broken via a hydrogen bond reconstruction strategy while achieving the modulation of the electric double-layer structure, which effectively suppresses the electrode interface proton activity. Consequently, the VO2 demonstrates excellent electrochemical performance at both ambient temperatures and -20 °C, especially maintaining a high capacity of 162 mAh g-1 at 5 A g-1 after a record-breaking 20 000 cycles. Notably, the all-vanadium symmetric pouch cells are successfully assembled for the first time based on the "rocking-chair" Mn2+/proton hybrid mechanism, demonstrating the practical application potential.

Perspective on Lewis Acid-Base Interactions in Emerging Batteries

Lewis acid-base interactions are common in chemical processes presented in diverse applications, such as synthesis, catalysis, batteries, semiconductors, and solar cells. The Lewis acid-base interactions allow precise tuning of material properties from the molecular level to more aggregated and organized structures. This review will focus on the origin, development, and prospects of applying Lewis acid-base interactions for the materials design and mechanism understanding in the advancement of battery materials and chemistries. The covered topics relate to aqueous batteries, lithium-ion batteries, solid-state batteries, alkali metal-sulfur batteries, and alkali metal-oxygen batteries. In this review, the Lewis acid-base theories will be first introduced. Thereafter the application strategies for Lewis acid-base interactions in solid-state and liquid-based batteries will be introduced from the aspects of liquid electrolyte, solid polymer electrolyte, metal anodes, and high-capacity cathodes. The underlying mechanism is highlighted in regard to ion transport, electrochemical stability, mechanical property, reaction kinetics, dendrite growth, corrosion, and so on. Last but not least, perspectives on the future directions related to Lewis acid-base interactions for next-generation batteries are like to be shared.

Atomic Level-Macroscopic Structure-Activity of Inhomogeneous Localized Aggregates Enabled Ultra-Low Temperature Hybrid Aqueous Batteries

The utilization of hybrid aqueous electrolytes has significantly broadened the electrochemical and temperature ranges of aqueous batteries, such as aqueous zinc and lithium-ion batteries, but the design principles for extreme operating conditions remain poorly understood. Here, we systematically unveil the ternary interaction involving salt-water-organic co-solvents and its intricate impacts on both the atomic-level and macroscopic structural features of the hybrid electrolytes. This highlights a distinct category of micelle-like structure electrolytes featuring organic-enriched phases and nanosized aqueous electrolyte aggregates, enabled by appropriate low donor number co-solvents and amphiphilic anions. Remarkably, the electrolyte enables exceptional high solubility, accommodating up to 29.8 m zinc triflate within aqueous micelles. This configuration maintains an intra-micellar salt-in-water setup, allowing for a broad electrochemical window (up to 3.86 V), low viscosity, and state-of-the-art ultralow-temperature zinc ion conductivity (1.58 mS cm-1 at -80 °C). Building upon the unique nature of the inhomogeneous localized aggregates, this micelle-like electrolyte facilitates dendrite-free Zn plating/stripping, even at -80 °C. The assembled Zn||PANI battery showcases an impressive capacity of 71.8 mAh g-1 and an extended lifespan of over 3000 cycles at -80 °C. This study opens up a promising approach in electrolyte design that transcends conventional local atomic solvation structures, broadening the water-in-salt electrolyte concept.

Investigating the NH4+ Preintercalation and Surface Coordination Effects on MnO2 for Ammonium-Ion Supercapacitors

Ion preintercalation is an effective method for fine-tuning the electrochemical characteristics of electrode materials, thereby enhancing the performance of aqueous ammonium-ion hybrid supercapacitors (A-HSCs). However, much of the current research on ion preintercalation lacks controllability, and the underlying mechanisms remain unclear. In this study, we employ a two-step electrochemical activation approach, involving galvanostatic charge-discharge and cyclic voltammetry, to modulate the preintercalation of NH4+ in MnO2. An in-depth analysis of the electrochemical activation mechanism is presented. This two-step electrochemical activation approach endows the final MnO2/AC electrode with a high capacitance of 917.4 F g-1, approximately 2.4 times higher than that of original MnO2. Furthermore, the MnO2/AC electrode retains approximately 93.4% of its capacitance after 10 000 cycles at a current density of 25 mA cm-2. Additionally, aqueous A-HSC, comprising MnO2/AC and P-MoO3, achieves a maximum energy density of 87.6 Wh kg-1. This study offers novel insights into the controllable ion preintercalation approach via electrochemical activation.

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 2300 h 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.

Triflate anion chemistry for enhanced four-electron zinc-iodine aqueous batteries

I+ hydrolysis, sluggish iodine redox kinetics and the instability of Zn anodes are the primary challenges for aqueous four-electron zinc-iodine batteries (4eZIBs). Herein, the OTf- anion chemistry in aqueous electrolyte is essential for developing advanced 4eZIBs. It is elucidated that OTf- anions establish weak hydrogen bonds (H bonds) with water to stabilize I+ species while optimizing a water-lean Zn2+ coordination structure to mitigate Zn dendrites and corrosion. Moreover, the interaction of the OTf- anions with the iodine species results in an increased equilibrium average intermolecular bond length of the iodine species, facilitating the 4e redox kinetics of iodine with improved reversibility.

Tuning the Solvation Structure in Water-Based Solution Enables Surface Reconstruction of Layered Oxide Cathodes toward Long Lifespan Sodium-Ion Batteries

Layered oxides of sodium-ion batteries suffer from severe side reactions on the electrode/electrolyte interface, leading to fast capacity degradation. Although surface reconstruction strategies are widely used to solve the above issues, the utilization of the low-cost wet chemical method is extremely challenging for moisture-sensitive Na-based oxide materials. Here, the solvation tuning strategy is proposed to overcome the deterioration of NaNi1/3Mn1/3Fe1/3O2 in water-based solution and conduct the surface reconstruction. When capturing the water molecules by the solvation structure of cations, here is Li+, the structural collapse and degradation of layered oxides in water-based solvents are greatly mitigated. Furthermore, Li(H2O)3EA+ promotes the profitable Li+/Na+ exchange to build a robust surface, which hampers the decomposition of electrolytes and the structural evolution upon cycling. Accordingly, the lifespan of Li-reinforced materials is prolonged to three times that of the pristine one. This work represents a step forward in understanding the surface reconstruction operated in a water-based solution for high-performance sodium layered oxide cathodes.

Gel polymer electrolytes for rechargeable batteries toward wide-temperature applications

Rechargeable batteries, typically represented by lithium-ion batteries, have taken a huge leap in energy density over the last two decades. However, they still face material/chemical challenges in ensuring safety and long service life at temperatures beyond the optimum range, primarily due to the chemical/electrochemical instabilities of conventional liquid electrolytes against aggressive electrode reactions and temperature variation. In this regard, a gel polymer electrolyte (GPE) with its liquid components immobilized and stabilized by a solid matrix, capable of retaining almost all the advantageous natures of the liquid electrolytes and circumventing the interfacial issues that exist in the all-solid-state electrolytes, is of great significance to realize rechargeable batteries with extended working temperature range. We begin this review with the main challenges faced in the development of GPEs, based on extensive literature research and our practical experience. Then, a significant section is dedicated to the requirements and design principles of GPEs for wide-temperature applications, with special attention paid to the feasibility, cost, and environmental impact. Next, the research progress of GPEs is thoroughly reviewed according to the strategies applied. In the end, we outline some prospects of GPEs related to innovations in material sciences, advanced characterizations, artificial intelligence, and environmental impact analysis, hoping to spark new research activities that ultimately bring us a step closer to realizing wide-temperature rechargeable batteries.