Ion Hybrid Supercapacitors Research Articles

Insights of Zinc Ion Storage in Chilli-Stem Derived Porous Carbon Enabling Ultrastability and High Energy Density of Zinc-Ion Hybrid Supercapacitors.

Aqueous zinc ion hybrid supercapacitors (ZIHSCs) are promising as low-cost and safe energy storage devices for next-generation applications. Still, their energy-power performance and durability are far from satisfactory. Here, we present an energy-dense, and ultrastable ZIHSC realized using activated porous carbons derived from chilli-stems. KOH activation resulted in a high specific surface area of 1710 m2/g, abundant mesoporous structure, and oxygen functionalities, which helped the KOH-activated carbon (CSK) to yield an impressive specific capacity and energy density of 192 mA h/g and 172 W h/kg, respectively, and makes it the top-performing ZIHSC in recent times. ZIHSC's cycling performance is exceptional, retaining over 90% capacity even after 50,000 charge-discharge cycles. Molecular dynamics simulations reveal easy Zn ion diffusion through interconnected channels and subsequent pore fillings within the carbon electrodes, rendering impressive performance. Simulations further reveal important atomic interactions, demonstrating that higher currents drawn from the device cause partial filling of pores and blockages in the channels and result in a decrease in the device's specific capacity. Benefitted by CSK's impressive performance, the aqueous Zn@pCu//CSK full-cell device has demonstrated good energy-power densities (57.7 W h/kg and 4.5 k W/kg) and durability over tens of thousands of cycles, further substantiating ZIHSCs' application prospects in real life.

Restricted growth of polyaniline nanofiber arrays between holey graphene sheets on carbon cloth towards improved charge storage capacity

The rapid−growing demand for flexible and wearable electronics has driven increased interest in developing porous electrodes with outstanding charge storage capacity especially areal capacity for polymeric and hybrid supercapacitors. Herein, unique porous polyaniline/holey graphene/carbon cloth (PANI/HG/CC) composite electrodes were constructed by combining rapid frozen interfacial polymerization and layer−by−layer spraying to restrict the growth of PANI nanofiber arrays between carbon−based materials. Benefiting from rapid charge transport, more electroactive sites and improved electrolyte penetration provided by hierarchical porous structure and highly oriented PANI nanofibers in the composite (P − G) by growing directly PANI array on the CC and applying graphene sheets as interlayer and cover layer, an areal specific capacitance of 3.22 F cm−2 at 5 mA cm−2 was achieved. A maximum areal energy density of up to 104.86 μWh cm−2, and excellent capacity retention of 89.5 % at 20 mA cm−2 after 5000 cycles also were achieved for flexible symmetric all−solid−state supercapacitor. Furthermore, the zinc−ion hybrid supercapacitor (P − G||Zn) assembled with P − G cathode and Zn anode could display a capacity of 217.7 mAh g−1 at 0.2 A g−1, and the maximum energy density of 130.6 Wh kg−1 at the power density of 120 W kg−1.

Zincophilic zwitterionic hydrogel electrolyte towards dendrite-free zinc ion hybrid supercapacitors with anti-self-discharge ability

Hydrogel-based zinc ion hybrid supercapacitors (ZHSCs) with high flexibility and appealing energy/power densities have attracted increasing attention in energy storage fields. However, the Zn dendrite growth, water-related side reactions, and fast self-charge issues lead to severe performance degeneration of hydrogel-based ZHSCs. Herein, a zwitterion L-carnitine (CN) was integrated into hydrogel electrolyte to construct a dendrite-free and anti-corrosive hydrogel-based ZHSC with a slow self-discharge rate. CN can enter the Zn2+ inner solvation sheath and isolate active water molecules from Zn anodes to induce homogeneous Zn2+ deposition and inhibit undesired side reactions. The CN ionic complexes serving as ion transport channels enable the Zn2+ to move along the migration channels, endowing the hydrogel electrolytes with a high Zn2+ transference number of 0.847. Besides, CN with zwitterionic groups forms electrostatic interactions with cations and anions, which prevents the diffusion of moveable ions from the electrode surfaces to hydrogel electrolytes, thus effectively prolonging the self-discharge time of ZHSCs. Accordingly, the hydrogel-based ZHSCs exhibit dendrite-free and corrosive-free behaviors on Zn electrodes after long-time operation, presenting a capacitance retention of 75 % after 2000 charge and discharge cycles at 1 A/g. The hydrogel-based ZHSC also display a long self-discharge time of 3h, which is more than 9 times that of the one without CN. This work provides guidance on the design of dendrite-free and anti-self-discharge hydrogel-based zinc ion energy storage devices.

Solvent self-doping synthesis of nitrogen/oxygen co-doped porous carbon from cellulose as high performance material for multipurpose energy storage

Developing novel heteroatoms co-doped biomass porous carbon with low-cost, tunable physical/chemical properties, and environmental friendliness is an important candidate to face energy shortage and environmental pollution currently. Herein, a novel solvothermal avenue was designed using triethanolamine as self-doping solvent to treat rice straw powders with KOH. The rice straw with triethanolamine derived carbon (RSTCs-1) possessed hierarchical porous structure, N/O diatomic doping, and large specific surface area. The electrochemical energy storage performance of RSTCs-1 was evaluated in the systems of supercapacitors, aqueous zinc ion hybrid supercapacitors (AZHSs), and lithium-ion batteries (LIBs) respectively. As the results, the RSTCs-1 based symmetric supercapacitor exhibited the maximum energy density of ca. 98.4 Wh·kg−1 with the excellent cycling stability. Moreover, both RSTCs-1 AZHSs and RSTCs-1 LIBs achieved the relative high discharge specific capacities of ca. 407.1 and 1906.7 mAh·g−1 at current density of 0.1 A·g−1. These results highlighted the huge potential of the obtained with notable electrochemical performance acting as multifunctional electrode material for the different energy storage devices.

MXene/Zwitterionic Hydrogel Oriented Anti‐freezing and High‐Performance Zinc–Ion Hybrid Supercapacitor

AbstractWith the wide application of portable electronic devices, zinc–ion hybrid supercapacitors (ZIHCs) have aroused great interest. However, balancing the low‐temperature performance and high energy density of ZIHCs remains a huge challenge. Herein, a zwitterionic hydrogel electrolyte (ZHE) loaded with carboxymethylcellulose and MXene is designed for ZIHCs, which shows excellent frost resistance and high output voltage. Carboxymethylcellulose and MXene enhance the flexibility and conductivity of the zwitterionic hydrogel electrolyte. Moreover, When ZnCl2 is introduced into a gel electrolyte, it induces an increase in the rate of ion transport, which enables a broadening of the operating temperature of the hydrogel (−40 °C–25 °C). As a result, Zn//AC ZIHCs based on ZHE show a high voltage window of 2 V, a high energy density (specific capacity) of 137 Wh kg−1 (247 F g−1), and the potential for wearable devices. This study will provide an effective strategy for the design of hydrogel ZIHCs with wide voltage windows, high energy density, and high practicality.

Inhibiting the zinc anodes corrosion to achieve ultra-stable high temperature aqueous zinc-ion hybrid supercapacitors

The corrosion of zinc anode significantly undermines the stability of aqueous zinc-based energy storage devices (ZnESDs), potentially leading to cell failure even explosions. In this study, we mixed a high concentration electrolyte (21 m LiTFSI) with a conventional 2 m Zn(OTF)2 electrolyte to highly reduce the activity of solvent water, which can greatly suppress the corrosion of zinc anode at room temperature and high temperatures. We systematically studied the phenomenon of ZnWiS inhibiting zinc anode corrosion at different temperatures and investigated its principle through experiments and theoretical calculations. As a result, the Zn||Zn symmetric cells demonstrated remarkable stability, sustaining over 3642 h at room temperature and over 112 h at 80 °C. Moreover, the as assembled aqueous zinc ion hybrid supercapacitors (ZHSC) also exhibited excellent cycling stability for over 5220 h at room temperature and over 165 h at 80 °C. In contrast, ZHSC assembled with 2 m Zn(OTF)2 can only cycle 80 h at room temperature, and 9 h at 80 °C. These findings confirm that reducing water activity in the electrolyte effectively contributes to achieving highly stable aqueous ZnESDs, and the universality of this strategy offering promise for its application in various aqueous metal ion energy storage devices.

Sodium anthraquinone-2-sulfonate combined with biomass porous carbon for high-performance zinc-ion hybrid supercapacitors

Zinc ion hybrid supercapacitors (ZIHSCs) can have their energy density raised by coupling high-capacity molecules with porous carbon, as demonstrated by research. However, few studies on the effect of introduction strategies of these molecules have been conducted on ZIHSC performance. Herein, sodium anthraquinone-2-sulfonate (AQS) are introduced into porous carbon (TAC) by one-step hydrothermal strategy to prepare the composites (TAC/AQS (W)). TAC/AQS (M) composites synthesized by physical mixing method as control samples. When used as the cathode material for aqueous ZIHSCs, TAC/AQS-1 (W) with the best mass ratio of AQS and TAC has a high specific capacitance of 310.89 mAh g−1 at 0.2 A g−1 and retains 89.17 % of its capacity after 20,000 cycles of the charge and discharge test, while those of TAC/AQS-0.5 (M) is 284.60 mAh g−1 and 10.09 %. Furthermore, TAC/AQS-1 (W) can achieve energy density of 295.35 Wh kg−1 and that of TAC/AQS-0.5 (M) is only 256.14 Wh kg−1. These results demonstrate that the way of introducing AQS affect the electrochemical properties of ZIHSC. The main reason for the difference in performance of two approaches is that the hydrothermal method makes AQS and TAC combine into a single solid phase with π-π non-covalent bonds, while the physical method is only a simple mechanical mixing of two phases.

Pulsed laser-modified zinc anode with improved dendrite and corrosion resistance for sustainable high performance zinc ion hybrid supercapacitors

This research explores the development and evaluation of zinc ion hybrid supercapacitors (ZIHSCs) with a focus on the enhanced performance and low corrosion attributes of pulsed laser-modified zinc anodes compared to their non-modified counterparts. These anodes, paired with cathodes crafted from activated carbon derived from jute sticks on graphite foil, were immersed in a 2 M zinc sulfate electrolyte. A pivotal aspect of the study is improving the electrochemical properties and corrosion resistance of zinc anodes achieved through precise pulsed laser modification. Extensive electrochemical testing was conducted to assess the capacitive behavior, energy storage capabilities, and durability of the supercapacitors during prolonged cycling. Hence, using the laser modified anode, we attain remarkable stability in Zn||Zn symmetric cells for 1000 h at high current density of 10 mA cm−2 with a capacity of 1 mAh cm−2, and ZIHSCs achieving specific capicitance up to 287 F/g at a current density of 0.1 A/g, and reaching an energy density of 102 Wh/kg while sustaining a power density of 80 W/kg. After 10,000 galvanostatic charge-discharge cycles, these supercapacitors maintained high capacitance values, underscoring their resilience. Notably, charge transfer resistance reduction, improved ion diffusion and enhanced corrosion resistance contributes to the supercapacitors' longevity and efficiency, which can be attributed to these anodes laser-induced surface alterations. This study highlights the crucial role of pulsed laser-modified zinc anodes in advancing ZIHSCs performance, marking a significant step towards achieving efficient and sustainable energy storage solutions.

A Comprehensive Review of Ammonium Ion Hybrid Supercapacitors: Exploring Recent Breakthroughs and Future Horizons

A Comprehensive Review of Ammonium Ion Hybrid Supercapacitors: Exploring Recent Breakthroughs and Future Horizons

Comparative study of the reduction techniques of Graphene Oxide for Zinc Ion hybrid Storage Application

The increasing demand for low cost and high energy storage devices has given rise to the hybrid supercapacitor device. To overcome the safety issues of the Lithium and Sodium-based devices Zinc ion hybrid supercapacitors (ZIHSCs) are a promising alternative. These devices amalgamate the energy density and power density requirements which makes them suitable for varied applications. The device construction comprises of a zinc anode, zinc-based electrolyte and capacitive type cathode material. Carbon based nanomaterials such as reduced graphene oxide (RGO) are predominantly used as potential cathodes. The strategies involved in obtaining RGO changes the structural characteristic of the samples. This study compares three different strategies such as Chemical reduction (c-RGO), Microwave reduction (m-RGO) and Solar reduction (s-RGO). It was observed that the employment of each these techniques render the change in the physical properties of the materials like number of defect, change in the surface are, porosity and in-situed developed functional group, especially oxygen species. These changes were analyzed thoroughly by various techniques like Raman, Fourier, X-ray diffraction and X-Ray photoelectron spectroscopy. The overall study reveals that solar reduction route shows enhanced surface area and porosity and decrease in defect concentration. Further due to this enhanced property in s-RGO the zinc ion storage capacitance of the fabricated ZIHSC was 200 F/g with a high cyclic stability of 5100 cycles at a current density of 10 A/g. The enhanced energy density thus obtained was 111 Wh/kg corresponding to a power density of 10 KW/kg.

Flexible zinc-ion hybrid micro-supercapacitors with polymeric current collector for integrated energy storage in wearable devices

The ubiquity of conventional micro-fabrication techniques has encountered impediments in constructing cost-effective micro-devices, thereby constraining their broad deployment. Concurrently, the suboptimal energy density inherent to supercapacitors exacerbates this challenge. This study presents a straightforward assembly methodology for the fabrication of a mechano-electrochemically efficient micro-zinc ion hybrid supercapacitor (M−ZSC), alongside the introduction of an innovative polymeric current collector. The M−ZSC is fabricated through a process involving masked spray deposition of a novel adhesive current collector and the electrode materials, and electroplating of zinc nanosheets onto the anode finger, creating an electrochemically performant and mechanically robust device. The resulting M−ZSC exhibits a notable areal capacitance of 52.2 mF/cm2 and an energy density of 18.5 µWh/cm2 for the normal mass-loading of 3.6 mg/cm2, which is amongst the highest reported values for energy storage. The masked spray deposition/hot pressing technique enabled us to fabricate free-standing thick electrodes with a loading density of up to 56.1 mg/cm2, facilitating the achievement of an ultrahigh areal capacitance of 227 mF/cm2 and an energy density of 80.5 µWh/cm2. Furthermore, the M−ZSC exhibits a robust retention of 95 % capacitance at 1 mA/cm2. Critical to its flexibility, the device is constructed using purely additive deposition methods on flexible substrates and is therefore well-tailored for deployment in flexible electronics and on-chip applications. These micro-devices are well-poised for seamless integration within a singular electronics package or chip architecture.

Hierarchical porous carbon with abundant N/O doping as an anode for zinc ion hybrid supercapacitors

Aqueous zinc-ion hybrid supercapacitors (ZISCs) known for their affordability, stability, and high energy density represent innovative energy storage devices. Porous carbon is usually used as the cathode material of ZISCs, and its structure significantly affects the dual performance of high power density and energy density of ZISCs. Herein, a one-pot carbonization strategy is proposed, eliminating the need for templates, additional heteroatom compounds, and activation processes. By precisely controlling the temperature to optimize the structure and electrochemical performance of carbon materials, we successfully synthesized hierarchical porous carbon materials (NOPC-800) with a high specific surface area of 1545.7 mg, featuring dual doping of 12.3 at% nitrogen and 13.35 at% oxygen. The self-doping of abundant nitrogen and oxygen atoms facilitates the chemical adsorption of ions and accelerates pseudocapacitive reaction kinetics. Leveraging these advantages, ZISCs were assembled using NOPC-800 as the positive electrode and zinc as the negative electrode, showcasing remarkable performance: a specific capacity of up to 121.9 mAh g, an energy density of 97.5 Wh kg, and a power density of up to 16000 W kg. Remarkably, NOPC-800 maintained an excellent capacity retention of 94.9% after 10,000 cycles at a current density of 10 A g. This research paves an innovative and feasible path for the design and advancement of novel heteroatom-rich carbon cathodes.

Dual–ion symmetric hybrid supercapacitor built by vanadium oxide with expanded interlayers: The intercalation of cation–anion pair and reversible redox of anion excited by Al3+

The development of aluminum ion batteries (AIBs) is retarded by the low capacity of intercalation cathode and ineffective aluminum dissolution/deposition at Al anode. To solve the issues, benzoquinone(BQ)–preinserted hydrated vanadium oxide formulated as (BQ)0.04V2O5·0.87H2O (BQ-VO) with a large interlayer spacing of 13.3 Å was synthesized, which was used as both cathode and anode with Al(ClO4)3 acetonitrile (AN) electrolyte to fabricate a symmetric aluminum–ion supercapacitor. BQ-VO delivers a large capacity of ~152 mAh g−1 at 0.2 A g−1 in the range of 0–1.5 V, which is associated with the intercalation of ion (such as ClO4−, Al3+ or Al3+ − ClO4− pair) into BQ-VO and the reversible redox reaction of ClO4− ↔ Cl−, giving rise to a novel symmetric dual–ion hybrid supercapacitor. The reversible conversion of ClO4− ↔ Cl− is not observed in NaClO4 AN electrolyte, which is only excited by Al3+, leading to a continuous increasing capacity in the early stage of the cycling test. On the contrary, in the NaClO4 AN electrolyte, BQ-VO illustrates a surface-controlled capacitive performance with excellent cycling stability. Molecular dynamic (MD) simulations reveal that Al3+ and Na+ possess different solvation/anion sheaths, leading to different electrochemical performances of BQ-VO in the Al(ClO4)3 and NaClO4 electrolytes. The present work provides a routine to utilize the redox reaction of halide for energy storage.

Cobalt Ion-Stabilized VO2 for Aqueous Ammonium Ion Hybrid Supercapacitors.

Aqueous ammonium ion hybrid supercapacitor (A-HSC) is an efficient energy storage device based on nonmetallic ion carriers (NH4+), which combines advantages such as low cost, safety, and sustainability. However, unstable electrode structures are prone to structural collapse in aqueous electrolytes, leading to fast capacitance decay, especially in host materials represented by vanadium-based oxidation. Here, the Co2+ preintercalation strategy is used to stabilize the VO2 tunnel structure and improve the electrochemical stability of the fast NH4+ storage process. In addition, the understanding of the NH4+ storage mechanism has been deepened through ex situ structural characterization and electrochemical analysis. The results indicate that Co2+ preintercalation effectively enhances the conductivity and structural stability of VO2, and inhibits the dissolution of V in aqueous electrolytes. In addition, the charge storage mechanisms of NH4+ intercalation/deintercalation and the reversible formation/fracture of hydrogen bonds were revealed.

High-performance Zn-ion hybrid supercapacitors based on biomass-derived hierarchical porous carbon through template-activated bifunctional induced and ice-crystal assisted strategy

As a highly desirable cathode material for Zn ion hybrid supercapacitors (ZHSCs), biomass-derived carbon precursor shrinks and collapses at elevated temperatures resulting in an impeded internal morphology, which severely hampers ion storage and transport. Herein, a unique porous carbon with multi-level pore structures is produced by a one-step carbonization-activation process. The Gelatin with rich functional groups is employed as the gel-state biomass precursor and the ZnCl2 acted as both a template and an activator. Furthermore, the growth of ice crystals during freeze-drying prevents the carbon framework from collapsing and self-polymerizing of ZnCl2, endowing the prepared porous carbon with a high specific surface area (1336 m2/g) and inheritance of biomass precursor heteroatoms (including N and O). Therefore, at 0.5 A/g, the prepared material displays a desirable specific capacitance of 337.6 F/g in 6 M KOH. In particular, the assembled ZHSC simultaneously shows excellent cycling performance (after 10000 cycles, the specific capacitance increases to 95.6% at 10 A/g) and high energy and power density (120.1 Wh/kg at 450 W/kg). This work provides important insights for the facile preparation of electrode materials for high-performance ZHSCs.

Self-adhesive, freeze-tolerant, and strong hydrogel electrolyte containing xanthan gum enables the high-performance of zinc-ion hybrid supercapacitors

Hydrogel electrolyte is an ideal candidate material for flexible energy storage devices due to its excellent softness and conductivity properties. However, challenges such as the inherent mechanical weakness, the susceptibility to be frozen in low-temperature environments, and the insufficiency of hydrogel-electrode contact persist. Herein, a “Multi in One” strategy is employed to effectively conquer these difficulties by endowing hydrogels with high strength, freeze-resistance, and self-adhesive ability. Multiple hydrogen bond networks and ion crosslinking networks are constructed within the hydrogel electrolyte (PVA/PAAc/XG) containing polyvinyl alcohol (PVA), acrylic acid (AAc), and xanthan gum (XG), promoting the enhanced mechanical property, and the adhesion to electrode materials is also improved through abundant active groups. The introduction of zinc ions provides the material with superior frost resistance while also promoting electrical conductivity. Leveraging its multifunction of superior mechanical strength, anti-freeze property, and self-adhesive characteristic, the PVA/PAAc/XG hydrogel electrolyte is employed to fabricate zinc ion hybrid supercapacitors (ZHS). Remarkably, ZHS exhibits outstanding electrochemical performance and cycle stability. A remarkable capacity retention rate of 83.86 % after 10,000 charge-discharge cycles can be achieved at high current densities, even when the operational temperature decreases to −60 °C, showing great potential in the field of flexible energy storage devices.

Polymer-mediated vacancy defects of graphene sheets as high-performance cathode materials for aqueous zinc-ion hybrid supercapacitors

The electrochemical behavior of graphene sheets in energy storage system is closely related to its electronic structures. Specifically, structural vacancy defects can expose more active sites and enhance the electrochemical performance. However, it is still a challenging problem to realize valid defect regulation on improving the reaction kinetics of electrode materials. Herein, vacancy-defective graphene sheets were constructed through the thermal mediated method via intercalation of polyacrylonitrile nanofibers. The vacancy defects were generated from the NH3 gas resulting from polymer decomposition at gradient carbonization temperature. The obtained composites of the graphene sheets and carbon nanofibers demonstrate that the vacancy defects benefit to charge transport, allowing more electrons to pass through the interlayered structure, and enhance the adsorption capacitance during the reversible electrochemical process. In addition, the as-assembled Zn ion hybrid supercapacitors exhibit a high energy density of 129.9 Wh kg−1 and outstanding cyclic stability (99.8 % after 10,000 cycling). The confined polymer-mediated thermal modification strategy can afford abundant vacancy defective sites and exhibit promising outlook for constructing high-performance graphene-based electrode materials for Zn ion hybrid supercapacitors.

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.

Nanosized Chevrel phases for dendrite-free zinc-ion based energy storage: unraveling the phase transformations.

The nanoscale form of the Chevrel phase, Mo6S8, is demonstrated to be a highly efficient zinc-free anode in aqueous zinc ion hybrid supercapacitors (ZIHSCs). The unique morphological characteristics of the material when its dimensions approach the nanoscale result in fast zinc intercalation kinetics that surpass the ion transport rate reported for some of the most promising materials, such as TiS2 and TiSe2. In situ Raman spectroscopy, post-mortem X-ray diffraction, Hard X-ray photoelectron spectroscopy, and density functional theory (DFT) calculations were combined to understand the overall mechanism of the zinc ion (de)intercalation process. The previously unknown formation of the sulfur-deficient Zn2.9Mo15S19 (Zn1.6Mo6S7.6) phase is identified, leading to a re-evaluation of the mechanism of the (de)intercalation process. A full cell comprised of an activated carbon (YEC-8A) positive electrode delivers a cell capacity of 38 mA h g-1 and an energy density of 43.8 W h kg-1 at a specific current density of 0.2 A g-1. The excellent cycling stability of the device is demonstrated for up to 8000 cycles at 3 A g-1 with a coulombic efficiency close to 100%. Post-mortem microscopic studies reveal the absence of dendrite formation at the nanosized Mo6S8 anode, in stark contrast to the state-of-the-art zinc electrode.

K-birnessite-MnO2/hollow mulberry-like carbon complexes with stabilized and superior rate performance for aqueous magnesium ion storage.

Manganese oxides are commonly employed as a cathode for magnesium ion storage in aqueous magnesium ion hybrid supercapacitors (MHS). However, sluggish reaction kinetics still hinders their practical application. Herein, we designed K-birnessite-MnO2 and electrostatically spun mulberry-like carbon composites (K-MnO2/HMCs) via an in situ growth technique. Benefiting from the 3D conductive carbon network substrate, the in situ fabricated K-MnO2 exhibits more active sites and provides more interfacial contact area between the electrode material and the electrolyte. This improvement enhances its conductivity, facilitating the rapid transfer of electrons, diffusion of ions, and redox reactions. As a result, K-MnO2/HMC-based MHS achieves a specific capacity of 168 mA h g-1 at 0.5 A g-1, simultaneously exhibiting a superior energy density of 111.1 W h kg-1 at a power density of 505 W kg-1. Furthermore, it demonstrates excellent high rate performance and a long cycling life for aqueous magnesium ion storage, offering new insights for MHS applications.