Asymmetric Electrolytes Research Articles

Colloidal phase behavior of high aspect ratio clay nanotubes in symmetric and asymmetric electrolytes

HypothesisImogolite nanotubes (INTs) are unique anisometric particles with monodisperse nanometric diameters. Aluminogermanate double-walled INTs (Ge-DWINTs) are obtained with variable aspect ratios by controlling the synthesis conditions. It thus appears as an interesting model system to investigate how aspect ratio and ionic valence influence the colloidal behavior of highly anisometric rods. ExperimentsThe nanotubes were synthesized by hydrothermal treatment for 5 or 20 days to modify the aspect ratio while the electrostatic interactions were investigated by comparing the colloidal stability in symmetric and asymmetric electrolytes. The phase behavior and their related microstructure were determined by optical observations and small-angle X-ray scattering measurements, coupled with interparticle distance modelling. FindingsWe revealed that colloidal suspensions of Ge-DWINTs prepared in NaCl are guided by repulsive double layer forces, undergoing different liquid crystal phase transitions before stiffen into a glass-like state. We found that the microstructure can be rationalized by taking into account the anisometric nature of the particles. By contrast, dispersions prepared with asymmetric electrolytes are governed by strong attractive forces and thus form space-filling gels containing large nanotubes aggregates.

Stable and High-performance Flow H2 -O2 Fuel Cells with Coupled Acidic Oxygen Reduction and Alkaline Hydrogen Oxidation Reactions.

Conventional H2 -O2 fuel cells suffer from the low output voltage, insufficient durability, and high-cost catalysts (e.g., noble metals). Herein, this work reports a conceptually new coupled flow fuel cell (CF-FC) by coupling asymmetric electrolytes for acidic oxygen reduction reaction and alkaline hydrogen oxidation reaction. By introducing an electrochemical neutralization energy, the newly-developed CF-FCs possess a significantly increased theoretical open-circuit voltage. Specifically, a CF-FC based on a typical transition metal single-atom Fe-N-C cathode catalyst demonstrates a high electricity output up to 1.81V and durability with an ultrahigh retention of 91% over 110h, far superior to the conventional fuel cells (usually, < 1.0V, < 50% retention over 20h). The output performance can even be significantly enhanced easily by connecting multiple CF-FCs into the parallel, series, or combined parallel-series connections at a fractional cost of that for the conventional H2 -O2 fuel cells, showing great potential for large-scale practical applications. Thus, this study provides a platform to transform conventional fuel cell technology through the rational design and development of advanced energy conversion and storage devices by coupling different electrocatalytic reactions.

Dynamic and Asymmetrical Ion Concentration Polarization in Dual Nanopipettes.

Dual nanopipettes with two channels have been receiving great attention due to the convenient experimental setup and multiple measuring channels in sensing applications at nanoscale, while the involved dynamic and asymmetrical ion transport processes have not been fully elucidated. In this paper, both experimental and simulation methods are used to investigate the dynamic mass transport processes inside dual nanopipettes with two well-separated channels. The results present that the ion transport resistance through the two channels (R12) is always the add-up of the individual ones (R13 + R23) with respect to the bulk solutions, at various ionic strengths and scan rates. A constant zero-current potential is obtained when loading an asymmetrical electrolyte concentration in the two channels, and the zero-potential current displays a good linear relationship with the bulk concentration outside the pipet. Besides revealing the dynamic and asymmetrical concentration polarization in the dual nanopipettes, these results would also further promote the better usage of dual nanopipettes in electrochemical sensing and imaging applications.

3D interconnected MOF-derived asymmetric bilayer solid-state electrolyte for enabling homogeneous Li deposition of all-solid-state lithium metal batteries

3D interconnected MOF-derived asymmetric bilayer solid-state electrolyte for enabling homogeneous Li deposition of all-solid-state lithium metal batteries

Stepwise strategies for overcoming limitations of membraneless electrolysis for direct seawater electrolysis

Direct seawater electrolysis (DSWE) has been investigated as a candidate solution for hydrogen (H2) production using abundant seawater without the water purification requirements of conventional electrolyzers. Costly perfluorinated membranes employed in contemporary water electrolyzers (PEMWE) fail in the presence of trace contaminants due to cation exchange for H+ and scaling resulting from Mg2+/Ca2+ hydroxide precipitation caused by local pH increases. Herein, we disclose a membraneless electrolyzer and explore how symmetric and asymmetric electrolyte recirculation schemes impact pH gradients and performance of the system using in-house developed near-neutral pH electrocatalysts. Under the asymmetric recycle scheme, unbuffered seawater feed can be used whereby pH differentials caused by electrolysis are re-balanced by recirculating the liquid anode and cathode effluent streams to the cathode and anode inlet ports, respectively. Cell voltages of 2.61 and 3.50 V were required to attain 100 mA cm−2 of current density under buffered (0.5 M phosphate buffer; pH 6.71) and unbuffered synthetic seawater operation, respectively, and 50 h of chronoamperometric stability at the same current density was achieved for the former. A mere 0.18 % of H2 crossover from the catholyte to the anolyte at 250 mA cm−2 of current density was recorded at prolonged operation.

Self‐Regulating Interfacial Space Charge through Polyanion Repulsion Effect towards Dendrite‐Free Polymer Lithium‐Metal Batteries

AbstractUncontrolled transport of anions leads to many issues, including concentration polarization, excessive interface side reactions, and space charge‐induced lithium dendrites at the anode/electrolyte interface, which severely deteriorates the cycling stability of lithium metal batteries. Herein, an asymmetrical polymer electrolyte modified by a boron‐containing single‐ion conductor (LiPVAOB), is designed to inhibit the nonuniform aggregation of free anions in the vicinity of the lithium anode through the repulsion effect improving the lithium‐ion transference number to 0.63. This LiPVAOB exerts a repulsion interaction with free anions even at a long distance and a selective effect for free anions transport, which diminishes uneven aggregation of free anions at the interface and suppresses space charges‐induced lithium dendrites growth. Consequently, the assembled Li||Li cell delivers an ultra‐long cycle for over 5400 h. The Li||LiFePO4 cell exhibits outstanding cycle performance with a capacity retention of 93% over 4500 cycles. In particular, the assembled high‐voltage Li||Li1.2Ni0.2Mn0.6O2 cell (charged to 4.8 V) exhibits good cycle stability with a high specific capacity of 245 mAh g−1. This designed polymer electrolyte provides a promising strategy for regulating ion transport to inhibit space charge‐induced lithium dendrite growth for high‐performance lithium metal batteries.

A novel asymmetrical multilayered composite electrolyte for high-performance ambient-temperature all-solid-state lithium batteries

A novel MSCE is designed by introducing a PEO layer against the cathode and a “self-sacrifice” PPC layer against the anode.

Electric field induced associations in the double layer of salt-in-ionic-liquid electrolytes.

Ionic liquids (ILs) are an extremely exciting class of electrolytes for energy storage applications. Upon dissolving alkali metal salts, such as Li or Na based salts, with the same anion as the IL, an intrinsically asymmetric electrolyte can be created for use in batteries, known as a salt-in-ionic liquid (SiIL). These SiILs have been well studied in the bulk, where negative transference numbers of the alkali metal cation have been observed from the formation of small, negatively charged clusters. The properties of these SiILs at electrified interfaces, however, have received little to no attention. Here, we develop a theory for the electrical double layer (EDL) of SiILs where we consistently account for the thermoreversible association of ions into Cayley tree aggregates. The theory predicts that the IL cations first populate the EDL at negative voltages, as they are not strongly bound to the anions. However, at large negative voltages, which are strong enough to break the alkali metal cation-anion associations, these IL cations are exchanged for the alkali metal cation because of their higher charge density. At positive voltages, we find that the SiIL actually becomes more aggregated while screening the electrode charge from the formation of large, negatively charged aggregates. Therefore, in contrast to conventional intuition of associations in the EDL, SiILs appear to become more associated in certain electric fields. We present these theoretical predictions to be verified by molecular dynamics simulations and experimental measurements.

Recent progress in energy-saving electrocatalytic hydrogen production via regulating the anodic oxidation reaction.

Hydrogen energy with its advantages of high calorific value, renewable nature, and zero carbon emissions is considered an ideal candidate for clean energy in the future. The electrochemical decomposition of water, powered by renewable and clean energy sources, presents a sustainable and environmentally friendly approach to hydrogen production. However, the traditional electrochemical overall water-splitting reaction (OWSR) is limited by the anodic oxygen evolution reaction (OER) with sluggish kinetics. Although important advances have been made in efficient OER catalysts, the theoretical thermodynamic difficulty predetermines the inevitable large potential (1.23 V vs. RHE for the OER) and high energy consumption for the conventional water electrolysis to obtain H2. Besides, the generation of reactive oxygen species at high oxidation potentials can lead to equipment degradation and increase maintenance costs. Therefore, to address these challenges, thermodynamically favorable anodic oxidation reactions with lower oxidation potentials than the OER are used to couple with the cathodic hydrogen evolution reaction (HER) to construct new coupling hydrogen production systems. Meanwhile, a series of robust catalysts applied in these new coupled systems are exploited to improve the energy conversion efficiency of hydrogen production. Besides, the electrochemical neutralization energy (ENE) of the asymmetric electrolytes with a pH gradient can further promote the decrease in application voltage and energy consumption for hydrogen production. In this review, we aim to provide an overview of the advancements in electrochemical hydrogen production strategies with low energy consumption, including (1) the traditional electrochemical overall water splitting reaction (OWSR, HER-OER); (2) the small molecule sacrificial agent oxidation reaction (SAOR) and (3) the electrochemical oxidation synthesis reaction (EOSR) coupling with the HER (HER-SAOR, HER-EOSR), respectively; (4) regulating the pH gradient of the cathodic and anodic electrolytes. The operating principle, advantages, and the latest progress of these hydrogen production systems are analyzed in detail. In particular, the recent progress in the catalytic materials applied to these coupled systems and the corresponding catalytic mechanism are further discussed. Furthermore, we also provide a perspective on the potential challenges and future directions to foster advancements in electrocatalytic green sustainable hydrogen production.

Transitioning Towards Asymmetric Gel Polymer Electrolytes for Lithium Batteries: Progress and Prospects

AbstractThe utilization of liquid electrolytes (LEs) concerns inevitable dendrite growth and safety issues. In contrast, solid polymer electrolytes suffer from unsettled low ionic conductivity and interfacial impedance issues. The intermediary gel polymer electrolytes (GPEs) improve safety by incorporating a sturdy polymer matrix and ionic conductivity as an advantage of percolating LEs responsible for gelation. The overall stability and compatibility of GPEs with different electrode materials depend on the polymers, plasticizers, and precursors utilized. No single polymer has a wide energy gap to exhibit stability against Li metal anodes and oxidative stability against high‐voltage cathodes. Thereafter, symmetric GPEs (SGPEs) possess limitations while simultaneously satisfying the two electrode requirements, which hinders their practical applications. Asymmetric GPEs (ASGPEs) generally comprise a bilayer or gradient structure, wherein the side contacting the cathode is modified to promote oxidative stability for a stable cathode electrolyte interface (CEI). The corresponding side in contact with the anode is modified to be mechanically and chemically compatible with dendritic lithium. Overall, asymmetric structural engineering enables electrode compatibility while maintaining the physical competency of GPEs. Herein, the focus is to summarize the current transition from SGPEs to asymmetric ones, which promotes multifunctionality while overcoming specific constraints associated with the electrodes.

Multilayer asymmetric solid polymer electrolyte with modified interface for high-voltage solid-state Li metal batteries

Solid polymer electrolytes (SPEs) are promising for achieving safe solid-state Li metal batteries (SSLMBs). However, unstable electrode/electrolyte interface contact of SPEs limits their application at high voltage. To address this issue, we designed a multi-layer asymmetric SPE with a sandwich structure based on the hydroxyapatite (HAP) enhanced PVDF-HFP matrix. Two different interfacial modification layers were introduced on the anode and cathode sides. Methyl (2,2,2-trifluoromethyl) carbonate (FEMC) and tetramethylene sulfone (TMS) were selected as plasticizers in the layers, respectively, contacting the anode and cathode to reduce the reactivity of the anode interface and enhance the high-voltage compatibility of the cathode interface. Unlike usual designs, each layer of the asymmetric SPE has essentially the same composition except the plasticizers, effectively eliminating interface resistance and promoting Li+ fast migration. Consequently, the asymmetric SPE exhibits excellent ionic conductivity at room temperature (8.8 × 10−4 S cm−1), superior interfacial stability, and Li dendrite inhibition ability. In addition, LiFePO4||SPE||Li cell demonstrates a stable retention rate of over 92 % after 500 cycles at 1 C. These findings provide a new approach for implementing SSLMBs under high voltage.

Asymmetric organic-inorganic bi-functional composite solid-state electrolyte for long stable cycling of high-voltage lithium battery

Poly(ethylene oxide) (PEO)-based solid-state electrolyte is difficult to achieve high voltage and energy density due to low ionic conductivity and narrow electrochemical stabilization window. Therefore, an urgent demand exists to construct a composite solid-state electrolyte that is resistant to both Li dendrite and high-voltage cathode oxidation. Here, we design and prepare an asymmetric bi-functional composite solid-state electrolyte achieving compatibility with Li anode and high-voltage anode to extend the cycle life of batteries. The F-containing hierarchically structured polyamide acids nanofibers towards the cathode side enhance interfacial compatibility with the cathode and provide excellent oxidation resistance. The rigid two-dimensional alumina nanosheets on the anode side further improve the interfacial stability with the Li anode and effectively inhibit the growth of Li dendrites. The synergistic effect of asymmetric organic-inorganic composite solid-state electrolyte is exploited to improve the cycling stability of different cathode (LiFePO4 (LFP) and LiNi0.8Mn0.1Co0.1O2 (NMC811))/Li batteries, greatly broaden the electrochemical stability window (5.3 V) and significantly enhance lithium dendrite inhibition. Based on density functional theory, the introduction of F-containing groups reduces the highest occupied molecular orbitals of the polyamide acids and that there is a strong binding between alumina and both the PEO terminal group and TFSI−. The result suggests that the composite solid-state electrolyte enhances the stability of PEO with the high-voltage cathode and Li anode, and inhibits the movement of anions. Therefore, it is noteworthy that the excellent electrochemical stability of this composite solid-state electrolyte with the NMC811/Li electrodes ensures long cycle of more than 800 cycles.

Brownian dynamics simulations and Ornstein-Zernike equation for charged fluids using the Wolf potential

From a computational point of view, a promising description for charged-stabilized fluids is the so-called Wolf method, which is faster than the standard Ewald summation technique. Using Monte Carlo computer simulations, it was recently shown that the static correlation functions of strong electrolytes obtained with the Wolf potential satisfy the Stillinger–Lovett sum rules, which are a consequence of perfect screening, and are directly related to the local electroneutrality condition and the electrostatic screening within the Debye–Hückel regime. In this contribution, the Wolf potential is adapted to Brownian dynamics simulations to study both the structural and dynamical properties of charged fluids. In addition, we have solved the Ornstein-Zernike equation with the Wolf potential using the HNC closure relation. The resulting radial distributions agree well with the simulation data and previous results obtained with the Ewald technique. Simulation results using Brownian dynamics for weakly charged colloidal dispersions and asymmetric electrolytes are presented. The results include mean square displacement, self-intermediate scattering, and shear relaxation function, with no consideration of hydrodynamic interactions. Including the Wolf potential in Brownian dynamics simulations opens up the possibility of studying interesting transport phenomena in the low Reynolds and Peclet regime, even in those cases where hydrodynamic interactions become relevant.

Ag nanodots-induced interfacial fast electronic/ionic diffusion kinetics of carbon capsule supported CoMn2O4 for high-voltage supercapacitors

The low energy density of SCs (<10 Wh kg−1) severely limits their commercial application, increasing either specific capacitance or broadening the potential window of the device is the effective pathway to improve the device energy density. Herein, nitrogen-doped carbon capsule (NC) supported Ag nanodots-decorated CoMn2O4 nanoflower (NC/CoMn2O4/Ag) electrode material has been successfully designed and synthesized. NC/CoMn2O4/Ag exhibits superior discharge capacity of 1806.4C/g, superior to NC/CoMn2O4 electrode (without Ag nanodots, 1319.2C/g at 1 A g−1). Theoretical calculations analysis demonstrates that decorated Ag nanodots on CoMn2O4 plays a fundamental role in improving the band gap, electrical conductivity, diffusion and transfer of electrolyte ions. In addition, asymmetric gel electrolytes of PVA-Na2SO4//PVA-KOH were designed for the assembly of asymmetric devices. This device delivers gravimetric energy density up to 89.9 Wh kg−1 at 894 W kg−1. The device can reach a large electrochemical voltage of up to 2.3 V, which could drive a remote-controlled toy easily. This work showcases a promising approach to rationally design conductive nanodots-decorated transition metal oxide-based materials towards high energy density supercapacitors. And it also sheds light on an in-depth understanding of their charge storage mechanisms.

Regulation of Lithium‐Ion Flux by Nanotopology Lithiophilic Boron‐Oxygen Dipole in Solid Polymer Electrolytes for Lithium‐Metal Batteries

Inhomogeneous lithium‐ion (Li+) deposition is one of the most crucial problems, which severely deteriorates the performance of solid‐state lithium metal batteries (LMBs). Herein, we discovered that covalent organic framework (COF‐1) with periodically arranged boron‐oxygen dipole lithiophilic sites could directionally guide Li+ even deposition in asymmetric solid polymer electrolytes. This in situ prepared 3D cross‐linked network Poly(ACMO‐MBA) hybrid electrolyte simultaneously delivers outstanding ionic conductivity (1.02 × 10−3 S cm−1 at 30 °C) and excellent mechanical property (3.5 MPa). The defined nanosized channel in COF‐1 selectively conducts Li+ increasing Li+ transference number to 0.67. Besides, The COF‐1 layer and Poly(ACMO‐MBA) also participate in forming a boron‐rich and nitrogen‐rich solid electrolyte interface to further improve the interfacial stability. The Li‖Li symmetric cell exhibits remarkable cyclic stability over 1000 h. The Li‖NCM523 full cell also delivers an outstanding lifespan over 400 cycles. Moreover, the Li‖LiFePO4 full cell stably cycles with a capacity retention of 85% after 500 cycles. the Li‖LiFePO4 pouch full exhibits excellent safety performance under pierced and cut conditions. This work thereby further broadens and complements the application of COF materials in polymer electrolyte for dendrite‐free and high‐energy‐density solid‐state LMBs.

Diffusiophoresis of a soft particle incorporating ion partitioning and hydrophobic core

The diffusiophoresis of a soft particle governed by an imposed ionic concentration gradient is studied based on a modified ion transport equation. The surface of the rigid core of the soft particle is considered to be hydrophobic, which is coated with a charged polyelectrolyte layer (PEL) whose dielectric constant is different from the dispersion medium. This step-change in the dielectric constant of the PEL and the dispersion medium creates an ion partitioning effect. The governing equations based on the coupled Navier–Stokes–Nernst–Planck–Poisson equations are modified to incorporate the ion partitioning effect. A simplified model based on the linear perturbation technique under a small applied concentration gradient in the scale of the particle radius is developed. The simplified model agrees well with the exact numerical solutions for a Debye length smaller than the particle size. We have analyzed the impact of the core slip length and PEL permittivity on the mobility of the soft particle. The interfacial slip enhances the impact of the core charge density on the diffusiophoresis. In this case, a reversal of mobility occurs at a thinner Debye length compared to a hydrophilic core. Ion partitioning attenuates the concentration of mobile counterions in PEL, leading to a reduction in screening of PEL fixed charge. We find that the diffusiophoresis of the soft particle in a non-z:z asymmetric electrolyte strongly depends on the valence of the counterions. Diffusiophoresis of the soft particle in a KCl-NaCl mixture is considered to achieve positive mobility.

Controlling the direction of steady electric fields in liquid using nonantiperiodic potentials.

When applying an oscillatory electric potential to an electrolyte solution, it is commonly assumed that the choice of which electrode is grounded or powered does not matter because the time average of the electric potential is zero. Recent theoretical, numerical, and experimental work, however, has established that certain types of multimodal oscillatory potentials that are "nonantiperiodic" can induce a net steady field toward either the grounded or powered electrode [A. Hashemi et al., Phys. Rev. E 105, 065001 (2022)2470-004510.1103/PhysRevE.105.065001]. Here, we elaborate on the nature of these steady fields through numerical and theoretical analyses of the asymmetric rectified electric field (AREF). We demonstrate that AREFs induced by a nonantiperiodic electric potential, e.g., by a two-mode waveform with modes at 2 and 3Hz, invariably yields a steady field that is spatially dissymmetric between two parallel electrodes, such that swapping which electrode is powered changes the direction of the field. Furthermore, we show that, while the single-mode AREF occurs in asymmetric electrolytes, nonantiperiodic electric potentials create a steady field in electrolytes even if the cations and anions have the same mobilities. Additionally, using a perturbation expansion, we demonstrate that the dissymmetric AREF occurs due to odd nonlinear orders of the applied potential. We further generalize the theory by demonstrating that the dissymmetric field occurs for all classes of zero-time-average (no dc bias) periodic potentials, including triangular and rectangular pulses, and we discuss how these steady fields can tremendously change the interpretation, design, and applications of electrochemical and electrokinetic systems.

Suppressing water migration in aqueous Zn-iodide flow batteries by asymmetric electrolyte formulation

Zinc-iodide flow battery (ZIFB) is under research for the last years due to its suitability as a potential candidate for future electrochemical energy storage. During cycling, one of the biggest challenges that affect the reliable performance of ZIFB is the substantial water migration through the membrane because of differential molar concentrations between anolyte and catholyte that imbalance the osmotic pressures in each compartment. Considering the mass balances, herein we propose to equalize the total ionic concentration of electrolytes by the addition of extra solute into the compartment of lower ion concentration as a way to restrict the water crossover. Experimental validation of this electrolyte concentrations balancing strategy has been carried out by assessing the post-cycled electrolytes, and half-cell charged electrolytes, which confirms the efficient suppression of water migration from catholyte to anolyte. Besides, in-depth analysis of ions and water transport mechanism through Nafion 117 membrane confirms that solvated K+ ions of lower ionic radius compared to solvated Zn2+ ions, are the dominant migrating carrier. Therefore, the addition of extra KI solute is beneficial to suppress the major transport of large hydrated Zn2+ ions along with the higher amount of water. Finally, the improved ZIFB cell behaviour with enhanced electrical conductivity, discharge capacity, and voltage efficiency in the cell assembled with the electrolytes of balanced molar concentrations concludes our present study, proving that tuning the electrolytes concentrations is an effective way to suppress water migration as an appealing method in the prospect of upscaling ZIFB application.

Diffusiophoresis of a Charged Droplet in Asymmetric as Well as Mixed Electrolytes through Numerical and Semianalytic Models

A numerical study on the diffusiophoresis of a droplet in an electrolyte medium is carried out by solving the full set of coupled governing equations, which are based on the conservation principle. Diffusiophoresis is considered for monovalent as well as non-z:z electrolytes and mixed electrolytes. The numerical model is supplemented with a semianalytic simplified model based on first-order perturbation analysis, which agrees with the numerical model for a low to moderate range of surface potential. The mobility for a low-viscosity fluid at a thinner Debye length is dominated by the chemiphoresis part, which creates the mobility to become an even function of the surface charge density for a monovalent electrolyte. Such a pattern in mobility does not appear in a non-z:z asymmetric electrolyte. At a thinner Debye length, diffusiophoresis becomes independent of the diffusion field, hence the mobility is independent of the composition of electrolytes in a mixed monovalent electrolyte solution. Our results show that the size-based sorting of droplets is efficient when a mixed electrolyte is considered. We have also addressed the finite ion size effects by considering a modified ion transport equation. One of the key features of the present study is the simplified semianalytical model for the diffusiophoresis of a droplet in a z:z electrolyte as well as in non-z:z and mixed electrolytes, which is shown to be valid up to a moderate range of surface potential for a finite Debye length.

An asymmetric electrolyte to simultaneously meet contradictory requirements of anode and cathode

One of the major obstacles hindering the application of zinc metal batteries is the contradictory demands from the Zn metal anode and cathodes. At the anode side, water induces serious corrosion and dendrite growth, remarkably suppressing the reversibility of Zn plating/stripping. At the cathode side, water is essential because many cathode materials require both H+ and Zn2+ insertion/extraction to achieve a high capacity and long lifespan. Herein, an asymmetric design of inorganic solid-state electrolyte combined with hydrogel electrolyte is presented to simultaneously meet the as-mentioned contrary requirements. The inorganic solid-state electrolyte is toward the Zn anode to realize a dendrite-free and corrosion-free highly reversible Zn plating/stripping, and the hydrogel electrolyte enables consequent H+ and Zn2+ insertion/extraction at the cathode side for high performance. Therefore, there is no hydrogen and dendrite growth detected in cells with a super high-areal-capacity up to 10 mAh·cm−2 (Zn//Zn), ~5.5 mAh·cm−2 (Zn//MnO2) and ~7.2 mAh·cm−2 (Zn//V2O5). These Zn//MnO2 and Zn//V2O5 batteries show remarkable cycling stability over 1000 cycles with 92.4% and over 400 cycles with 90.5% initial capacity retained, respectively.