Aqueous Dual-ion Research Articles

Deciphering the Degradation Mechanisms and Realize High-Voltage Stability of A3V2(PO4)3 (A=Li+, Na+) in Aqueous Dual-Ion Batteries.

Polyanionic A3V2(PO4)3 (A=Li+, Na+) with open channels have been extensively utilized as cathode materials for aqueous zinc-metal batteries (AZMBs), whereas suffering from severe capacity fading and rapid operation voltage decay during cycling. when used as In this work, it is disclosed that the rapid degradation is induced by an irreversible phase change from electrochemical active Li3V2(PO4)3 to nonactive monoclinic LiZnPO4, as well as active Na3V2(PO4)3 to nonactive rhombic Zn3(PO4)2(H2O)4. Subsequently, a rational dual-cation (Al-Fe) doping strategy is proposed to suppress these detrimental transformations. Such dual-cation doping entails stronger P-O and V-O bonds, thus stabilizing the initial polyanionic structures. Consequently, the optimized member of Li3V1.775Al0.075Fe0.225(PO4)3 (LVAFP) exhibits desirable cycling stability (1000 cycles, 68.5% capacity retention) and notable rate capability (92.1% of the initial capacity at 10 C). Moreover, the dual-cation doping methodology is successfully extended to improve the stability of Na3V2(PO4)3 cathode in aqueous dual-ion batteries, signifying the versatility and feasibility of this strategy. The comprehensive identification of local structural evolution in these polyanions will broaden the scope of designing high-performance alkali-vanadyl-phosphates for multivalent aqueous batteries.

Regulating the Porosity and Bipolarity of Polyimide-Based Covalent Organic Framework for Advanced Aqueous Dual-Ion Symmetric Batteries.

The all-organic aqueous dual-ion batteries (ADIBs) have attracted increasing attention due to the low cost and high safety. However, the solubility and unstable activity of organic electrodes restrict the synergistic storage of anions and cations in the symmetric ADIBs. Herein, a novel polyimide-based covalent organic framework (labeled as NTPI-COF) is constructed, featured with the boosted structure stability and electronic conductivity. Through regulating the porosity and bipolarity integrally, the NTPI-COF possesses hierarchical porous structure (mesopore and micropore) and abundant bipolar active centers (C═O and C─N), which exhibits rapid dual-ion transport and storage effects. As a result, the NTPI-COF as the electrodes for ADIBs deliver a high reversible capacity of 109.7mAhg-1 for Na+ storage and that of 74.8mAhg-1 for Cl- storage at 1Ag-1, respectively, and with a capacity retention of 93.2% over 10000 cycles at 10Ag-1. Additionally, the all-organic ADIBs with symmetric NTPI-COF electrodes achieve an impressive energy density of up to 148Whkg-1 and a high power density of 2600Wkg-1. Coupling the bipolarity and porosity of the all-organic electrodes applied in ADIBs will further advance the development of low-cost and large-scale energy storage.

Enhanced Discharge Capacity in Carbon Felt Electrodes for Aqueous Aluminium-Ion Half-Cells

Diversifying the battery technology in use is an important step in ensuring a sustainable transition to a carbon neutral society, and reducing the emissions associated with lithium-ion cell manufacture. Aluminium is an attractive material for battery applications due to its high theoretical volumetric charge storage capacity of 8046 mA h cm−3 compared to lithium’s 2061 mAh cm-3 and relative abundance in the earth’s crust (1). Aqueous Al-ion batteries are one of many metal-ion systems being investigated utilising water as the electrolyte (2). Further, there are well-established mining, processing, and recycling routes for aluminium, with Li-ion battery recycling still in its infancy (3). Using aqueous electrolytes further provides improved safety as fire risk is reduced, and manufacturing costs are also reduced (4).The substrate on which the electrode material is applied impacts how it is utilised within an electrochemical system. The substrate provides both a shape to the electrode, as well as the material itself forming part of the system, and common substrates double as current collectors e.g. thin metal foils, but carbon polymers have also been explored as a substrate (5, 6). Carbon felt is a conductive substrate, with thin fibres of 5-10 μm diameter, providing a flexible porous structure and large surface area for the active material ‘ ink’ to adhere (0.4 m2 g-1 (7)) . Carbon based electrodes have been assessed in a non-aqueous Al-ion cathodes (8), with varying performance metrics based on the structure and make-up of the electrode, however, these were not investigated as a substrate for further electrode ink. In adding the ink to the carbon felt, the electrode becomes an effective 3D-matrix electrode.This poster explores the use of such 3D-matrix electrodes in order to increase the amount of active material utilised within the aq. Al-ion battery system (9) – a key requirement in reducing the environmental impacts of the battery overall (5), and a means for increasing the capacity of an individual electrode without increasing the overall volume. The cell described in (10) has a carbon-polymer electrode substrate, anatase TiO2 negative electrode and a copper hexacyanoferrate (CuHCF) positive electrode, with the electrolyte being 1 M AlCl3 + 1 M KCl. While the CuHCF redox reaction is partially understood, the negative electrode mechanism has not been fully elucidated. A theorised surface reaction, and pseudo-capacitance of the TiO2 electrode in the aq. Al-ion battery would benefit from an increased surface area of the electrode provided by the carbon felt. Therefore, a key factor in achieving the optimum utilisation of active material is not purely an increase of TiO2 in the electrode, but an increase in the surface area in contact with the electrolyte. Key findings presented show that the lower active material loadings result in a higher discharge capacity for both the positive and negative electrodes, with values reaching an order of magnitude higher than seen for the 2D electrodes studied in the past. For the TiO2 electrode, we see 205.0 mAh g-1 @978 mA g-1 (1.81 mg cm-2 active material loading) and for the CuHCF, 259 mA h g-1 @ 1256.8 mA g-1 (2.5 mg cm-2 active material loading). Elia GA, Kravchyk KV, Kovalenko MV, Chacón J, Holland A, Wills RGA. An overview and prospective on Al and Al-ion battery technologies. Journal of Power Sources. 2021;481:228870. Wu D, Li X, Liu X, Yi J, Acevedo-Peña P, Reguera E, et al. 2022 Roadmap on aqueous batteries. Journal of Physics: Energy. 2022;4(4):041501. Baum ZJ, Bird RE, Yu X, Ma J. Lithium-ion battery recycling─ overview of techniques and trends. ACS Publications; 2022. Chao D, Zhou W, Xie F, Ye C, Li H, Jaroniec M, et al. Roadmap for advanced aqueous batteries: From design of materials to applications. Science Advances. 2020;6:eaba4098. Melzack N. Advancing battery design based on environmental impacts using an aqueous Al-ion cell as a case study. Scientific Reports. 2022;12(1):8911. Holland A, Kimpton H, Cruden A, Wills R. CuHCF as an electrode material in an aqueous dual-ion Al3+/K+ ion battery. Energy Procedia. 2018 d;151:69-73. Sigracell. Speciality Graphites for Energy Storage. 2016. McKerracher RD, Holland A, Cruden A, Wills RGA. Comparison of carbon materials as cathodes for the aluminium-ion battery. Carbon. 2019;144:333-41. Holland A, McKerracher RD, Cruden A, Wills RGA. An aluminium battery operating with an aqueous electrolyte. Journal of Applied Electrochemistry. 2018;48(3):243-50. Melzack N, Wills R, Cruden A. Cleaner Energy Storage: Cradle-to-Gate Life Cycle Assessment of Aluminum-Ion Batteries With an Aqueous Electrolyte. Frontiers in Energy Research. 2021;9(290).

2D Conjugated Metal-Organic Frameworks Bearing Large Pore Apertures and Multiple Active Sites for High-Performance Aqueous Dual-Ion Batteries.

2D conjugated metal-organic frameworks (2D c-MOFs) with large pore sizes and high surface areas are advantageous for adsorbing iodine species to enhance the electrochemical performance of aqueous dual-ion batteries (ADIBs). However, most of the reported 2D c-MOFs feature microporous structures, with few examples exhibiting mesoporous characteristics. Herein, we developed two mesoporous 2D c-MOFs, namely PA-TAPA-Cu-MOF and PA-PyTTA-Cu-MOF, using newly designed arylimide based multitopic catechol ligands (6OH-PA-TAPA and 8OH-PA-PyTTA). Notably, PA-TAPA-Cu-MOF exhibits the largest pore sizes (3.9 nm) among all reported 2D c-MOFs. Furthermore, we demonstrated that these 2D c-MOFs can serve as promising cathode host materials for polyiodides in ADIBs for the first time. The incorporation of triphenylamine moieties in PA-TAPA-Cu-MOF resulted in a higher specific capacity (423.4 mAh g-1 after 100 cycles at 1.0 A g-1) and superior cycling performance, retaining 96 % capacity over 1000 cycles at 10 A g-1 compared to PA-PyTTA-Cu-MOF. Our comparative analysis revealed that the increased number of N anchoring sites and larger pore size in PA-TAPA-Cu-MOF facilitate efficient anchoring and conversion of I3 -, as supported by spectroscopic electrochemistry and density functional theory calculations.

Anion storing, oxygen vacancy incorporated perovskite oxide composites for high-performance aqueous dual ion hybrid supercapacitors

Dual ion storage hybrid supercapacitors (HSCs) are considered as a promising device to overcome the limited energy density of existing supercapacitors while preserving high power and long cyclability. However, the development of high-capacity anion-storing materials, which can be paired with fast charging capacitive electrodes, lags behind cation-storing counterparts. Herein, we demonstrate the surface faradaic OH− storage mechanism of anion storing perovskite oxide composites and their application in high-performance dual ion HSCs. The oxygen vacancy and nanoparticle size of the reduced LaMnO3 (r-LaMnO3) were controlled, while r-LaMnO3 was chemically coupled with ozonated carbon nanotubes (oCNTs) for the improved anion storing capacity and cycle performance. As taken by in-situ and ex-situ spectroscopic and computational analyses, OH− ions are inserted into the oxygen vacancies coordinating with octahedral Mn with the increase in the oxidation state of Mn during the charging process or vice versa. Configuring OH− storing r-LaMnO3/oCNT composite with Na+ storing MXene, the as-fabricated aqueous dual ion HSCs achieved the cycle performance of 73.3% over 10,000 cycles, delivering the maximum energy and power densities of 47.5 W h kg−1 and 8 kW kg−1, respectively, far exceeding those of previously reported aqueous anion and dual ion storage cells. This research establishes a foundation for the unique anion storage mechanism of the defect engineered perovskite oxides and the advancement of dual ion hybrid energy storage devices with high energy and power densities.

Additive-rejuvenated anions (De)intercalation into graphite cathode enables optimum dual-ion battery

Cathode-electrolyte interphase (CEI) has particular function in maintaining electrolyte and cathode stability. However, the CEI will also cause some negative effects on ion transport. It is crucial for optimizing the structure of CEI through additives in the electrolyte to improve the electrode reaction. In this study, we proposed using C3H3FO3 (FEC) as an additive to optimize an aqueous LiTFSI (bistrifluoromethanesulfonimide lithium salt) electrolyte. The incorporation of FEC modified the solvation structure of TFSI–, inhibit the formation of CEI with thicker size, thereby facilitating the intercalation of TFSI– into the selected graphite cathode. Consequently, the graphite's discharge capacity was doubled, reaching 47 mAh g−1. The influence of TFSI– solvation structure on CEI formation was further studied by the emerging correlative SEM, Raman imaging and TOF-SIMS techniques and theoretical calculation techniques. Using this optimization strategy, we successfully constructed an aqueous dual-ion battery using C24H10N2O4 and graphite as the anode and cathode with an impressive potential window of 2.55 V, which delivered the energy density of 66 Wh kg−1 at the power density of 128 W kg–1.

Anion electrostatic insertion boosts efficient zinc ferrocyanide cathode for aqueous dual-ion battery

Prussian blue analogs (PBAs) have been considered as a kind of promising cathode materials, but its poor cycle performance severely hinders their industrialization. Herein, by combining a zinc ferrocyanide (ZnHCF) cathode with aqueous ZnSO4/LiTFSI electrolyte and zinc metal anode, we achieved a stable anion insertion-type aqueous dual-ion battery (DIB) which displays a discharge specific capacity of 75.9 mAh g–1, an energy density of 124 Wh kg–1, and a discharge plateau of 1.8 V at 5 A g–1. Its specific capacity can still reach 57.4 mAh g–1 after 1200 cycles with a Coulombic efficiency of 97 %. A reversible anion insertion mechanism of ZnHCF cathode based on the changes of the valency of iron and the insertion of TFSI– ion on crystal surface caused by electrostatic interaction is proposed and confirmed with a series of characterizations and density functional theory calculations (DFT). This work proposes the study of anion energy storage mechanism of PBAs and brings more opportunities for their large-scale applications in the future.

Conversion-intercalation competing behaviour of halogen storage on graphite electrode from fluid ZnCl2/ZnBr2 hydrates.

Zinc-based aqueous dual-ion batteries (ADIBs) with halogen-graphite intercalation compound positive electrodes are among the most competitive candidates for next-generation electrochemical energy storage systems. However, most of the electrolytes employed have been gel-like electrolytes; hence, a fundamental understanding of the halogen storage process using fluid hydrates will be essential for constructing efficient Zn-based ADIBs. Herein, the halogen storage mechanism on a graphite electrode from fluid ZnCl2/ZnBr2 hydrates is studied by experimental and computational methods. The results indicate that the halogen storage mechanism is a competition between conversion and intercalation. Moreover, the macroscopic electrode reaction is determined by both the ion-pair solvation state at the graphite-electrolyte interface and the subsequent reactant supply is influenced by the electrode reaction rate.

Nanocomposite of Nb-based binary phase for lowering the activation energy of Li+ intercalation as an anode for high-performance aqueous dual-ion batteries

A Nb-based binary-phase composite anode delivers a higher capacity in an aqueous dual-ion battery and suppresses water splitting to achieve a higher coulombic efficiency and long cycle life.

High Voltage and Capacity Dual-Ion Battery Using Acetonitrile-Aqueous Hybrid Electrolyte with Concentrated LiFSI-LiTFSI

Water-acetonitrile (AN) hybrid electrolyte with high concentration of bis(trifluoromethanesulfonyl) imide (LiTFSI) and Lithium bis(fluorosulfonyl) imide (LiFSI) (LiTFSI-LiFSI=3:1, molar ratio) supporting salts are studied for the high potential and large capacity rechargeable dual-ion battery. Water-acetonitrile hybrid electrolyte (WA) shows a wide electrochemical stability window of 3.1 V in 20 m aqueous electrolyte and 3.6 V in 20 m 9LiFSI-1LiTFSI in water: AN=1:3 molar ratio electrolyte. In particular, high oxidation potential, which can be assigned to the strong solvated ionic cluster formed between AN, water and LiTFSI-LiFSI supporting salts. The dual-ion battery is assembled using the graphitic carbon (KS6) and the activated carbon (AC) as cathode and anode, respectively, and 20 m LiTFSI-LiFSI in hybrid AN-water as electrolyte. It is found that the reasonably large capacity, coulombic efficiency and cycle stability were achieved. The KS6/AC cell shows 86 mAh g−1 at the initial cycle and 50 mAh g−1 at 100th cycle in a voltage range of 0–3.25 V, and the average coulombic efficiency of 85% is sustained over 200 cycles. The solvated structure of water to Li+ is strengthened by addition of AN from ATR-IR and NMR spectrums analysis and this change in the solvated structure is the main reason for the increased performance of the aqueous dual-ion battery.

Charge Carriers for Aqueous Dual-Ion Batteries.

Environmental and safety concerns of energy storage systems call for application of aqueous battery systems which have advantages of low cost, environmental benignity, safety, and easy assembling. Among the aqueous battery systems, aqueous dual-ion batteries (ADIBs) provide high possibility for achieving excellent battery performance. Compared with the "rocking chair" batteries with only one type of carrier involved in the charging and discharging, ADIBs with both cations and anions as charge carriers possess diverse selections of electrodes and electrolytes. Charge carriers are the basis of the configuration of ADIBs. In this Review, cations and anions that could be applied in ADIBs are demonstrated with corresponding electrode materials and favorable electrolytes. Some insertion mechanisms are emphasized to provide insights for the possibilities to enhance the practical performances of ADIBs.

Anchoring I3- via Charge-Transfer Interaction by a Coordination Supramolecular Network Cathode for a High-Performance Aqueous Dual-Ion Battery.

Iodine is considered to have broad application prospects in the field of electrochemical energy storage. However, the high solubility of I3- severely hampers its practical application, and the lack of research on the anchoring mechanism of I3- has seriously hindered the development of advanced cathode materials for iodine batteries. Herein, based on the molecular orbital theory, we studied the charge-transfer interaction between the acceptor of I3- with a σ* empty antibonding orbital and the donor of pyrimidine nitrogen with lone-pair electrons, which is proved by the results of UV-vis absorption spectroscopy, Raman spectroscopy, and density functional theory (DFT) calculations. The prepared dual-ion battery (DIB) exhibits a high voltage platform of 1.2 V, a remarkable discharge-specific capacity of up to 207 mAh g-1, and an energy density of 233 Wh kg-1 at a current density of 5 A g-1, as well as outstanding cycle stability (operating stably for 5000 cycles) with a high Coulombic efficiency of 97%, demonstrating excellent electrochemical performance and a promising prospect in stationary energy storage.

Highly Concentrated Salt Electrolyte for a Highly Stable Aqueous Dual-Ion Zinc Battery.

A zinc metal anode for zinc-ion batteries is a promising alternative to solve safety and cost issues in lithium-ion batteries. The Zn metal is characterized by its high theoretical capacity (820 mAh g-1), low redox potential (0.762 V vs SHE), low toxicity, high abundance on Earth, and high stability in water. Taking advantage of the stability of Zn in water, an aqueous Zn ion battery with low cost, high safety, and easy-to-handle features can be developed. To minimize water-related parasitic reactions, this work utilizes a highly concentrated salt electrolyte (HCE) with dual salts─1 m Zn(OTf)2 + 20 m LiTFSI. MD simulations prove that Zn2+ is preferentially coordinated with O in the TFSI- anion from HCE instead of O in H2O. HCE has a broadened electrochemical stability window due to suppressed H2 and O2 evolution. Some advanced ex situ and in situ/in operando analysis techniques have been applied to evaluate the morphological structure and the composition of the in situ formed passivation layer. A dual-ion full Zn||LiMn2O4 cell employing HCE has an excellent capacity retention of 92% after 300 cycles with an average Coulombic efficiency of 99.62%. Meanwhile, the low concentration electrolyte (LCE) cell degrades rapidly and is short-circuited after 66 cycles with an average Coulombic efficiency of 96.91%. The battery's excellent cycling performance with HCE is attributed to the formation of a stable anion-derived solid-electrolyte interphase (SEI) layer. On the contrary, the high free water activity in LCE leads to a water-derived interfacial layer with unavoidable dendrite growth during cycling.

Stable and High-Performance Organ0ic Aqueous Dual-Ion Batteries with Polyaniline/CNTs Cathode

Organic aqueous dual-ion batteries are accepted as the next-generation energy storage strategy for large-scale systems of energy storage to address the flammable and electrochemical stability problems that are encountered in lithium-ion batteries. However, conventional organic materials are restricted by high solubility in electrolytes during the process of discharging. Here, we present an integrated organic aqueous dual-ion battery that contains a stable, highly electrically conductive polymer as an effective cathode material for aqueous batteries. The battery has a capacity of 134 mAh g−1 and a cycle life of 700 cycles at a current density of 1 A g−1.

Deciphering and suppressing the cathode dissolution catastrophe in aqueous rechargeable dual-ion battery

The development of aqueous dual-ion batteries (DIBs) has been hampered by two omnipresent issues, i.e. limited ESW of electrolyte and unsatisfactory electrode dissolution. In this study, a new DIB concept based on Cl[Formula: see text] and Na[Formula: see text] dual ion shutting with a sodium chloride (NaCl) aqueous electrolyte was reported. The electrochemical stable window (ESW) of the aqueous electrolyte was improved by inducing the urea to stabilize the shared water (H2O) molecule in the solvation sheath around Na[Formula: see text] and Cl[Formula: see text] based on the “water-in-salt” mechanism. Furthermore, an artificial SEI layer was introduced to inhibit the dissolution of Na3V[Formula: see text]Fe[Formula: see text](PO[Formula: see text] (Fe-NVP) cathode, thus ensuring a good cycling stability over 300 cycles of the aqueous DIB with an average discharging voltage of [Formula: see text]0.67 V. These exciting results advance the fundamental understanding of the artificial protective SEI and high-performance “water-in-salt” electrolyte design in developing cheap, stable aqueous DIB systems.

A Graphite∥PTCDI Aqueous Dual-Ion Battery.

A full cell chemistry of aqueous dual-ion battery (DIB) was reported, comprising the graphite cathode and 3,4,9,10-perylenetetracarboxylic diimide (PTCDI) as the anode. This DIB employed a mixture aqueous electrolyte: 5 m tributylmethylammonium (TBMA) chloride plus 5 m MgCl2 , where [MgCl3 ]- and TBMA+ serve as the charge carriers for cathode and anode of the DIB, respectively. This novel full cell exhibited a specific capacity of around 41 mAh g-1 based on the total active mass of both electrodes with an average operation voltage of 1.45 V and stable cycling for 400 cycles.

Manipulating anion intercalation enables a high-voltage aqueous dual ion battery

Aqueous graphite-based dual ion batteries have unique superiorities in stationary energy storage systems due to their non-transition metal configuration and safety properties. However, there is an absence of thorough study of the interactions between anions and water molecules and between anions and electrode materials, which is essential to achieve high output voltage. Here we reveal the four-stage intercalation process and energy conversion in a graphite cathode of anions with different configurations. The difference between the intercalation energy and hydration energy of bis(trifluoromethane)sulfonimide makes the best use of the electrochemical stability window of its electrolyte and delivers a high intercalation potential, while BF4− and CF3SO3− do not exhibit a satisfactory potential because the graphite intercalation potential of BF4− is inferior and the graphite intercalation potential of CF3SO3− exceeds the voltage window of its electrolyte. An aqueous dual ion battery based on the intercalation behaviors of bis(trifluoromethane)sulfonimide anions into a graphite cathode exhibits a high voltage of 2.2 V together with a specific energy of 242.74 Wh kg−1. This work provides clear guidance for the voltage plateau manipulation of anion intercalation into two-dimensional materials.

Semi-coherent cation-rich Mn-Cu oxides heterostructures as cathode for novel aqueous potassium dual-ion energy storage devices

In this work, combining both advantages of aqueous energy storage systems (ESS) and conventional dual-ion ESS, a novel aqueous dual-ion ESS is developed based on K+ and OH– electrochemistry by employing semi-coherent K1.33Mn8O16-CuO (sc–Mn–Cu) cathode. Profting from the elaborate design, the electrolyte and cathode simultaneously act as source of cations. In the novel aqueous dual-ion ESS configuration, the dependence of the performance on the electrolyte salt concentration is reduced and the sc–Mn–Cu cathode can host OH− with lower working potentials by conversion mechanism. Furthermore, based on the sc–Mn–Cu cathode and freestanding V2O3–VC (fs-V2O3–VC) anode, we developed a flexible quasi-solid-state device. Remarkably, it exhibits an ultrahigh energy density of ~39.9 μW h cm−2 together with high power density of carbon-based devices, which outperforms most previously reported flexible storage devices to our knowledge. These results indicating that the unique mechanism of the sc–Mn–Cu cathode opens up a promising direction for low-cost and high-performance novel aqueous ESS.

A novel aqueous dual-ion battery using concentrated bisalt electrolyte

A high-concentration aqueous electrolyte with a wide electrochemical stability window represents a novel development direction for traditional aqueous batteries. Herein, a novel high-concentration water-in-bisalt electrolyte using LiFSI (lithium bis(fluorosulfonyl)imide) and LiTFSI (lithium bis(trifluoromethanesulfonyl)imide) as supporting salts was first applied as an electrolyte of a dual-ion battery, and the solvated structure changes were studied in detail. Electronic interactions were detected between the two supporting salts. Furthermore, when 37 mol/kg LiFSI-LiTFSI/H2O was applied to a 3 V dual-ion battery, by using graphitic carbon (KS6) and activated carbon (AC) as cathode and anode materials, the full cell delivered a high specific capacity of 72 mAh/g. In addition, excellent cycling stability for ˃100 cycles was achieved with negligible capacity fading.

Water-Salt Oligomers Enable Supersoluble Electrolytes for High-Performance Aqueous Batteries.

Aqueous rechargeable batteries are highly safe, low-cost, and environmentally friendly, but restricted by low energy density. One of the most efficient solutions is to improve the concentration of the aqueous electrolytes. However, each salt is limited by its physical solubility, generally below 21-32molkg-1 (m). Here, a ZnCl2 /ZnBr2 /Zn(OAc)2 aqueous electrolyte with a record super-solubility up to 75 m is reported, which breaks through the physical solubility limit. This is attributed to the formation of acetate-capped water-salt oligomers bridged by Br- /Cl- -H and Br- /Cl- /O-Zn2+ interactions. Mass spectrometry indicates that acetate anions containing nonpolarized protons prohibit the overgrowth and precipitation of ionic oligomers. The polymer-like glass transition temperature of such inorganic electrolytes is found at ≈-70 to -60°C, without the observation of peaks for salt-crystallization and water-freezing from 40 to -80°C. This supersoluble electrolyte enables high-performance aqueous dual-ion batteries that exhibit a reversible capacity of 605.7mAhg-1 , corresponding to an energy density of 908.5Whkg-1 , with a coulombic efficiency of 98.07%. In situ X-ray diffraction and Raman technologies reveal that such high ionic concentrations of the supersoluble electrolyte enable a stage-1 intercalation of bromine into macroscopically assembled graphene cathode.