Charge Storage Mechanism Research Articles

Boosting the Proton Intercalation via Crystal Plane Optimization of TiS2 for Cycling‐Stable Aqueous Zn‐Ion Batteries

AbstractTiS2 has received significant attention as a promising anode for “Rocking‐Chair”‐type aqueous Zn‐ion batteries due to the large interlayer spacing and low discharge plateau. However, the structural distortion caused by the embedding of divalent Zn2+ as well as the undesirable hydrogen evolution reaction (HER) severely affects their cycling stability. Herein, a facet‐dependent mechanism is first deeply investigated to understand charge storage behaviors of TiS2 via differential electrochemical mass spectrometry, in situ electrochemical quartz crystal microbalance, and in situ X‐ray diffraction characterizations. By regulating the exposed crystal facets of TiS2 from (001) (TS (001)) to (011) (TS(011)), HER can be effectively inhibited, and the charge storage mechanism is transformed from Zn2+ insertion/extraction dominating to H+ insertion/extraction dominating, resulting in faster charge transfer kinetics and strong structure stability during long‐term cycling. Hence, TS(011) delivers a higher reversible capacity of 212.9 mAh g−1 at 0.1 A g−1 and a strong cycling stability of 74% capacity retention over 1000 cycles, much better than that of TS (001) with a reversible capacity of 164.7 mAh g−1 at 0.1 A g−1, a capacity retention of 17% after 1000 cycles. These new findings can provide deep insight into the rational design of high‐performance intercalation‐type electrode materials for energy storage applications.

Exploring Impact of Various Operating Parameters on the Specific Capacitance at the Glassy Carbon/H2SO4 Interface: A Comparative Analysis Using Electrochemical Characterization

AbstractThe aim of this study is to investigate the influence of scanning rate, electrolyte concentration, temperature and electrode rotation speed on the capacitance of glassy carbon electrode in sulfuric acid solution using cyclic voltammetry (CV). The results show that they have a significant influence on the capacitance with varying experimental conditions. In addition, the electrochemical impedance spectroscopy (EIS) method was employed to conduct a more thorough analysis of the ways in which hydrodynamic circumstances resulting from a rotating electrode affect the electrode capacity and the charge storage process. Step potential electrochemical spectroscopy (SPECS) was used to identify the various charge storage mechanisms involved. It was shown that the voltammograms measured by the CV method and determined from the SPECS method have a quasi‐rectangular shape, revealing a predominantly capacitive behavior and that capacitance decreases with increasing scanning rate. Furthermore, both methods confirm that the contribution of the diffusion process is the main factor influencing the charge storage mechanism when the sweep rate is taken into account. However, the SPECS approach provides more accurate and detailed information regarding the kinetic characteristics of the electrode.

A fast-charging/discharging and long-term stable artificial electrode enabled by space charge storage mechanism

Lithium‐ion batteries with fast-charging/discharging properties are urgently needed for the mass adoption of electric vehicles. Here, we show that fast charging/discharging, long-term stable and high energy charge-storage properties can be realized in an artificial electrode made from a mixed electronic/ionic conductor material (Fe/LixM, where M = O, F, S, N) enabled by a space charge principle. Particularly, the Fe/Li2O electrode is able to be charged/discharged to 126 mAh g−1 in 6 s at a high current density of up to 50 A g−1, and it also shows stable cycling performance for 30,000 cycles at a current density of 10 A g−1, with a mass-loading of ~2.5 mg cm−2 of the electrode materials. This study demonstrates the critical role of the space charge storage mechanism in advancing electrochemical energy storage and provides an unconventional perspective for designing high-performance anode materials for lithium-ion batteries.

Green Plasma Enhanced Synthesis of Multi-Phase NiMnO3 Cathode for Aqueous Zn-Ion Batteries

Rechargeable Zn-ion batteries have the potential to address the need for cheap and widely accessible energy storage. Metal-doped manganese oxide cathodes are a common and effective choice for Zn-ion batteries. Zn-ion battery development can be advanced by overcoming the poor cycle life that many metal-doped Mn-oxide cathodes suffer from. Plasma-treated water (PAW) is created using low input power of 0.145 kWh per liter of PAW and is used to accelerate the reduction and precipitation of MnO4 − and nickel acetate (Ni(Ac)) to form a multiphase NiMnO3 electrode with Ni2+ and Ni3+ doped into the MnO6 octahedra, which exhibits capacitance dominated charge storage mechanisms. The electrode shows initial specific capacitance of 60.1 F g−1 and a capacitance retention of 100.8% after 10,000 cycles and 92.2% after 12,000 cycles. The beneficial layer of nanoflake morphology is formed during cycling, which causes a rapid increase in specific capacitance due to the larger electrochemically active surface area and the associated surface adsorption-based (pseudo-capacitive) type charge storage. We also demonstrate the capability of our multiphase NiMnO3 electrode to be coupled with a Zn metal anode in a battery cell which exhibits 330 mAh g−1 peak specific capacity and capacity retention of 63.8% after 380 cycles.

Lithium storage behaviour of AgNbO3 perovskite: Understanding electrochemical activation and charge storage mechanisms

In this study, a model AgNbO3 perovskite is prepared via polyacrylamide synthesis technique, and the underlying unique Li+storage mechanism is studied. This structure is projected to provide low Li+ storage capacity due to all occupied crystallographic sites. It delivered a specific capacity of 17 mAh.g−1 at 0.1A.g−1 within the potential range of 1.2–3.0 V vs. Li+/Li. However, at lower potentials, the material undergoes activation for Li+ storage by a multistep structural transition that included in-situ Ag-exsolution from the A-site of the lattice and an electrochemically induced crystalline-to-amorphous transition. At low potential the materials delivers high specific capacity (226 mAh.g−1 at 0.1 A.g−1 in 0.01–3 V vs. Li+/Li potential range) due to the contribution of improved Nb-redox activity and nanoscale Ag-Li (de)alloying mechanisms that were comprehensively examined utilizing advanced characterization tools. In addition, good capacity retention of 72 mAh.g−1 at high current density of 2A.g−1 and an excellent cyclic stability with coulombic efficiencies above 99.9 % are obtained for 2500 cycles at 1 A.g−1 underlining the performance and the stability of AgNbO3. This study introduces an alternative approach for tailoring electrode material using an electrochemically driven in-situ activation process. It also serves as a paradigm for the use of exsolved materials as negative electrodes in fast-charging batteries, paving the way for a better understanding of charge storage mechanisms in perovskites.

Poly(ethylene‐thiosuccinate)/carbon allotrope/cubic nickel‐cobalt hexacyanoferrate nanoparticles nanocomposites as supercapacitor materials

AbstractThis paper reports the synthesis of poly(ethylene‐thiosuccinate) (PETS) using succinic anhydride and 1,2‐ethanedithiol monomers and investigates its electrochemical behavior as supercapacitor electrode material. The synthesized polymer's structure is designed so that to contain sulfur atoms in the main chain of polymer, as the sulfur containing polymers are among the interesting active compounds for fabricating of novel devices for energy storage with wider voltage window and increase the energy density. The cyclic voltammetry (CV) graphs show the supercapacitor behavior of the materials with the faradic charge storage mechanism. The triangular shape of the charge–discharge curves indicate the reversible performance of the PETS as an electrode material. To enhance the supercapacitive action of PETS, its nanocomposites including PETS/Norit (1:1), PETS/MWCNT (1:1) and PTES/MWCNT (1:1)/(1.5%, 3% and 5%) Ni2CoHCF (nickel‐cobalt hexacyanoferrate) is prepared. The results indicate that the PETS/MWCNT/0.15% Ni2CoHCF nanocomposite exhibits a specific capacity which is 7 times higher than that of the PETS/MWCNT (1:1) nanocomposite, when the current density is 0.05 mA.cm−2. Also, according to the Nyquist diagrams, by incorporating of 1.5% of Ni2CoHCF in the PETS/MWCNT (1:1) nanocomposite, its electrical resistance decreases significantly by about two times.Highlights Poly(ethylene‐thiosuccinate) (PETS) made by succinic anhydride & ethanedithiol PETS/Norit or MWCNT/cubic Ni2CoHCF nanoparticles composites are prepared PETS/MWCNT composites as supercapacitor materials by Faradic storage mechanism PETS/1.5% Ni2CoHCF showed 0.0449 mF.cm−2 specific capacity at 0.01 mA.cm−2

Understanding Electrolyte Ion Size Effects on the Performance of Conducting Metal-Organic Framework Supercapacitors.

Layered metal-organic frameworks (MOFs) have emerged as promising materials for next-generation supercapacitors. Understanding how and why electrolyte ion size impacts electrochemical performance is crucial for developing improved MOF-based devices. To address this, we investigate the energy storage performance of Cu3(HHTP)2 (HHTP = 2,3,6,7,10,11-hexahydroxytriphenylene) with a series of 1 M tetraalkylammonium tetrafluoroborate (TAABF4) electrolytes with different cation sizes. Three-electrode experiments show that Cu3(HHTP)2 exhibits an asymmetric charging response with all ion sizes, with higher energy storage upon positive charging and a greater charging asymmetry with larger TAA+ cations. The results further show that smaller TAA+ cations demonstrate superior capacitive performances upon both positive and negative charging compared to larger TAA+ cations. To gain further insights, electrochemical quartz crystal microbalance measurements were performed to probe ion electrosorption during charging and discharging. These reveal that Cu3(HHTP)2 has a cation-dominated charging mechanism, but interestingly indicate that the solvent also participates in the charging process with larger cations. Overall, the results of this study suggest that larger TAA+ cations saturate the pores of the Cu3(HHTP)2-based electrodes. This leads to more asymmetric charging behavior and forces solvent molecules to play a role in the charge storage mechanism. These findings significantly enhance our understanding of ion electrosorption in layered MOFs, and they will guide the design of improved MOF-based supercapacitors.

Mechano-driven logic-in-memory with neuromorphic triboelectric charge-trapping transistor

In the post-Moore's Law era, there is a growing trend towards the development of advanced electronic devices that combine sensory perception, data storage, and computation for various applications. Two-dimensional semiconductor transistors, which utilize charge storage mechanisms, present a promising avenue for future information devices. Here, we introduce a neuromorphic triboelectric charge-trapping MoTe2 transistor with stacked high-k dielectric structure, aiming to facilitate mechano-driven logic-in-memory for neuromorphic computation. By gating through triboelectric potential, the device demonstrates superior electrical performance, including an impressive switching ratio (>105), minimal off-state current (∼0.6 pA), and robust cyclic stability. By modulating the trapped charges in the stack gate structure via tribopotential modulation, the conductivity state of the MoTe2 channel can be readily controlled, realizing an exceptional mechano-driven nonvolatile memory with a retention time of up to 104 seconds, consistent switching behavior over 100 cycles, and multi-level data storage capabilities at 8 levels. Furthermore, a mechano-driven programmable inverter can be achieved by connecting a load resistor in series. The triboelectric charge-trapping transistor also possesses the capacity to emulate typical synaptic characteristics at low energy levels (∼147 fJ). Leveraging the finely tunable conductivity through tribopotential, we demonstrate a mechano-assisted artificial neural network capable of recognizing handwritten digits with an accuracy rate of approximately 88.59%. These findings underscore the significant potential of the triboelectric charge-trapping transistor in mechanical-assisted real-time interaction, energy-efficient data storage, and neuromorphic computing.

Charge Storage Properties of Ferrimagnetic BaFe12O19 and Polypyrrole-BaFe12O19 Composites.

This investigation is motivated by an interest in multiferroic BaFe12O19 (BFO), which combines advanced ferrimagnetic and ferroelectric properties at room temperature and exhibits interesting magnetoelectric phenomena. The ferroelectric charge storage properties of BFO are limited due to high coercivity, low dielectric constant, and high dielectric losses. We report the pseudocapacitive behavior of BFO, which allows superior charge storage compared to the ferroelectric charge storage mechanism. The BFO electrodes show a remarkably high capacitance of 1.34 F cm-2 in a neutral Na2SO4 electrolyte. The charging mechanism is discussed. The capacitive behavior is linked to the beneficial effect of high-energy ball milling (HEBM) and the use of an efficient dispersant, which facilitates charge transfer. Another approach is based on the use of conductive polypyrrole (PPy) for the fabrication of PPy-BFO composites. The choice of new polyaromatic dopants with a high charge-to-mass ratio plays a crucial role in achieving a high capacitance of 4.66 F cm-2 for pure PPy electrodes. The composite PPy-BFO (50/50) electrodes show a capacitance of 3.39 F cm-2, low impedance, reduced charge transfer resistance, enhanced capacitance retention at fast charging rates, and good cyclic stability due to the beneficial effect of advanced dopants, HEBM, and synergy of the contribution of PPy and BFO.

Intermolecular Hydrogen Bonding Networks Stabilized Organic Supramolecular Cathode for Ultra‐High Capacity and Ultra‐Long Cycle Life Rechargeable Aluminum Batteries

AbstractRechargeable aluminum batteries (RABs) are a promising candidate for large‐scale energy storage, attributing to the abundant reserves, low cost, intrinsic safety, and high theoretical capacity of Al. However, the cathode materials reported thus far still face challenges such as limited capacity, sluggish kinetics, and undesirable cycle life. Herein, we propose an organic cathode benzo[i] benzo[6,7] quinoxalino [2,3‐a] benzo [6,7] quinoxalino [2,3‐c] phenazine‐5,8,13,16,21,24‐hexaone (BQQPH) for RABs. The six C=O and six C=N redox active sites in each molecule enable BQQPH to deliver a record ultra‐high capacity of 413 mAh g−1 at 0.2 A g−1. Encouragingly, the intermolecular hydrogen bonding network and π–π stacking interactions endow BQQPH with robust structural stability and minimal solubility, enabling an ultra‐long lifetime of 100,000 cycles. Moreover, the electron‐withdrawing carbonyl group induces a reduction in the energy level of the lowest unoccupied molecular orbital and expands the π‐conjugated system, which considerably enhances both the discharge voltage and redox kinetics of BQQPH. In situ and ex situ characterizations combined with theoretical calculations unveil that the charge storage mechanism is reversible coordination/dissociation of AlCl2+ with the N and O sites in BQQPH accompanied by 12‐electron transfer. This work provides valuable insights into the design of high‐performance organic cathode materials for RABs.

Intermolecular Hydrogen Bonding Networks Stabilized Organic Supramolecular Cathode for Ultra-High Capacity and Ultra-Long Cycle Life Rechargeable Aluminum Batteries.

Rechargeable aluminum batteries (RABs) are a promising candidate for large-scale energy storage, attributing to the abundant reserves, low cost, intrinsic safety, and high theoretical capacity of Al. However, the cathode materials reported thus far still face challenges such as limited capacity, sluggish kinetics, and undesirable cycle life. Herein, we propose an organic cathode benzo[i] benzo[6,7] quinoxalino [2,3-a] benzo [6,7] quinoxalino [2,3-c] phenazine-5,8,13,16,21,24-hexaone (BQQPH) for RABs. The six C=O and six C=N redox active sites in each molecule enable BQQPH to deliver a record ultra-high capacity of 413 mAh g-1 at 0.2 A g-1. Encouragingly, the intermolecular hydrogen bonding network and π-π stacking interactions endow BQQPH with robust structural stability and minimal solubility, enabling an ultra-long lifetime of 100,000 cycles. Moreover, the electron-withdrawing carbonyl group induces a reduction in the energy level of the lowest unoccupied molecular orbital and expands the π-conjugated system, which considerably enhances both the discharge voltage and redox kinetics of BQQPH. In situ and ex situ characterizations combined with theoretical calculations unveil that the charge storage mechanism is reversible coordination/dissociation of AlCl2 + with the N and O sites in BQQPH accompanied by 12-electron transfer. This work provides valuable insights into the design of high-performance organic cathode materials for RABs.

Functionalized interfacial cover design toward pure silicon anode for high power density lithium–ion capacitor

A lithium–ion capacitor, comprising a capacitor–type cathode and battery–type anode, exhibits high power and energy density; however, the integration of different charge storage mechanisms in one cell naturally leads to a kinetic mismatch between the two electrodes, reducing the power density and cycle stability. To solve this problem, high–capacity anode materials with thinner electrodes are required. Silicon, with its high specific capacity, is considered a promising anode material with high energy and power density; however, pure Si anodes undergo rapid capacity fading and exhibit increased internal resistance owing to volume changes during cycling. In this study, both sides of the electrode are covered with functional layers consisting of functionalized herringbone–type carbon nanofibers to protect the Si electrode from degradation. The polar functional groups on the nanofibers weakly interact with the native oxide layer of the Si surface and the carboxyl groups of the binder, ensuring stable contact between electrode materials over repeated cycles. Moreover, the conductive functional cover promotes uniform lithium ion fluxes, aiding the formation of a stable solid electrolyte interphase layer. This study investigates the effects of this strategy on pure Si electrodes by surface morphology analysis, assessment of chemical interactions, and electrochemical testing. This approach has the potential to overcome the degradation of Si electrodes and significantly improve the power and energy density of lithium–ion capacitors.

Multivalent-Ion versus Proton Insertion into Nanostructured Electrochromic WO3 from Mild Aqueous Electrolytes.

Mild aqueous electrolytes containing multivalent metal salts are currently scrutinized for the development of ecosustainable energy-related devices. However, the role of soluble multivalent metal ions in the electrochemical reactivity of transition metal oxides is a matter of debate, especially when they are performed in protic aqueous electrolytes. Here, we have compared, by means of (spectro)electrochemistry, the reversible electrochromic reduction of transparent nanostructured γ-WO3 thin films in mild aqueous electrolytes of various chemical composition and pH. This study reveals that reversible proton insertion is the only charge storage mechanism over a large pH range and that it is effective for aqueous electrolytes prepared from either organic (such as acetic acid) or inorganic (such as solvated multivalent cations) Bro̷nsted acids. By refuting charge storage mechanisms relying on the reversible insertion of multivalent metal ions, notably in aqueous electrolytes based on Al3+ ions or a mixture of Al3+ and Zn2+ ions, these fundamental results pave the way for the rational development of electrolytes and active materials for a range of aqueous-based devices, such as the emerging concept of an energy-saving smart window, which we also address in this study.

Heteroatom Doping in Pollutant Diesel Soot-Derived Nanocarbon for Enhanced Zn-Ion Storage Performance.

Herein, we have isolated onion-like nanocarbon (ONC) from the exhaust soot of diesel engines and further doped it with nitrogen (N) and sulfur (S) to fabricate N,S-co-doped ONC (N-S-ONC). To explore its application feasibility, we have assembled an aqueous Zn-ion hybrid supercapacitor (ZIHSC) with a N-S-ONC cathode, which attains high specific capacitance with good rate capability. In-depth analyses suggest that the mechanism of charge storage in the ONC is governed by both capacitive-controlled and diffusion-controlled processes, with the capacitive processes leading at all sweep rates. The ZIHSC demonstrated a good energy density of 50 Wh/kg, a maximum power density of 3.6 kW/kg, and an impressive cycle life with 73% capacitance retention after 50,000 charge-discharge cycles. The study suggests the potential possibly for the long-term application of BC derived nanocarbon in electrochemical energy storage systems (EESSs).

Cation-driven self-assembly of core–shell covalent organic frameworks@Ti3CN MXene nanospheres for high-performance aqueous zinc-ion hybrid supercapacitors

Rechargeable aqueous Zn-ion hybrid supercapacitors (ZISCs) with the superiorities of high theoretical capacity, low redox potential and aqueous electrolytes with superior ionic conductivity (∼1 S cm−1) are promising energy storage systems. However, a primary concern persists due to the absence of cathode materials with both high energy densities and satisfactory cycling stability for robust ZISCs. In this study, we design a spherical core–shell covalent organic frameworks@Ti3CN MXene (CM-P) cathode via a cation-driven electrostatic self-assembly strategy. The CM-P with the constructed heterostructures shows both well-organized pore channels and excellent intrinsic conductivity, facilitating fast accessibility to intrinsic redox-active sites (such as C = O and N), and promoting effective ion diffusion characterized by low energy barriers. Consequently, the CM-P cathodes demonstrate excellent electrochemical performance, featuring an ultrahigh specific capacity of 260 mAh/g at 0.1 A, a high-rate capability with 68 % retention at 1 A/g, and long-term cycling stability. First-principle calculations elucidate that the enhanced charge-storage mechanism relies on the heterostructures of CM-P, accelerating ion adsorption/diffusion and electron transfer. Furthermore, the assembled CM-P//Zn ZISCs devices show a high energy density of 217.1 Wh kg−1 along with power density of 22.3 kW kg−1. This work provides an innovative approach to design COFs-based heterostructures for advanced ZISCs.

Averting H+-Mediated Charge Storage Chemistry Stabilizes the High Output Voltage of LiMn2O4-Based Aqueous Battery.

H+ co-intercalation chemistry of the cathode is perceived to have damaging consequences on the low-rate and long-term cycling of aqueous zinc batteries, which is a critical hindrance to their promise for stationary storage applications. Herein, the thermodynamically competitive H+ storage chemistry of an attractive high-voltage cathode LiMn2O4 is revealed by employing operando and ex-situ analytical techniques together with density functional theory-based calculations. The H+ electrochemistry leads to the previously unforeseen voltage decay with cycling, impacting the available energy density, particularly at lower currents. Based on an in-depth investigation of the effect of the Li+ to Zn2+ ratio in the electrolyte on the charge storage mechanism, a purely aqueous and low-salt concentration electrolyte with a tuned Li+/Zn2+ ratio is introduced to subdue the H+-mediated charge storage kinetically, resulting in a stable voltage output and improved cycling stability at both low and high cathode loadings. Synchrotron X-ray diffraction analysis reveals that repeated H+ intercalation triggers an irreversible phase transformation leading to voltage decay, which is averted by shutting down H+ storage. These findings unveiling the origin and impact of the deleterious H+-storage, coupled with the practical strategy for its inhibition, will inspire further work toward this under-explored realm of aqueous battery chemistry.

Recent development in addressing challenges and implementing strategies for manganese dioxide cathodes in aqueous zinc ion batteries

Safety issues of energy storage devices in daily life are receiving growing attention, together with resources and environmental concerns. Aqueous zinc ion batteries (AZIBs) have emerged as promising alternatives for extensive energy storage due to their ultra-high capacity, safety, and eco-friendliness. Manganese-based compounds are key to the functioning of AZIBs as the cathode materials thanks to their high operating voltage, substantial charge storage capacity, and eco-friendly characteristics. Despite these advantages, the development of high-performance Mn-based cathodes still faces the critical challenges of structural instability, manganese dissolution, and the relatively low conductivity. Primarily, the charge storage mechanism of manganese-based AZIBs is complex and subject to debate. In view of the above, this review focuses on the mostly investigated MnO2-based cathodes and comprehensively outlines the charge storage mechanisms of MnO2-based AZIBs. Current optimization strategies are systematically summarized and discussed. At last, the perspectives on elucidating advancing MnO2 cathodes are provided from the mechanistic, synthetic, and application-oriented aspects.

Exploring Lead Zirconate Titanate, the Potential Advancement as an Anode for Li-Ion Batteries.

Graphite, widely adopted as an anode for lithium-ion batteries (LIBs), faces challenges such as an unsustainable supply chain and sluggish rate capabilities. This emphasizes the urgent need to explore alternative anode materials for LIBs, aiming to resolve these challenges and drive the advancement of more efficient and sustainable battery technologies. The present research investigates the potential of lead zirconate titanate (PZT: PbZr0.53Ti0.47O3) as an anode material for LIBs. Bulk PZT materials were synthesized by using a solid-state reaction, and the electrochemical performance as an anode was examined. A high initial discharge capacity of approximately 686 mAh/g was attained, maintaining a stable capacity of around 161 mAh/g after 200 cycles with diffusion-controlled intercalation as the primary charge storage mechanism in a PZT anode. These findings suggest that PZT exhibits a promising electrochemical performance, positioning it as a potential alternative anode material for LIBs.

Boosting Spatial Charge Storage in Ion-Compatible Pores of Carbon Superstructures for Advanced Zinc-Ion Capacitors.

Capacitive carbon cathodes deliver great potential for zinc-ion hybrid capacitors (ZHCs) due to their resource abundance and structural versatility. However, the dimension mismatch between the micropores of carbons and hydrated Zn2+ ions often results in unsatisfactory charge storage capability. Here well-arranged heterodiatomic carbon superstructures are reported with compatible pore dimensions for activating Zn2+ ions, initiated by the supramolecular self-assembly of 1,3,5-triazine-2,4,6-triamine and cyanuric acid via in-plane hydrogen-bonds and out-of-plane π-π interactions. Flower-shaped carbon superstructures expose more surface-active motifs, continuous charge-transport routes, and more importantly, well-developed pores. The primary subnanopores of 0.82nm are size-exclusively accessible for solvated Zn2+ ions (0.86nm) to maximize spatial charge storage, while rich mesopores (1-3nm) allow for high-kinetics ion migration with a low activation energy. Such favorable superstructure cathodes contribute to all-round performance improvement for ZHCs, including high energy density (158Whkg-1), fast-charging ability (50Ag-1), and excellent cyclic lifespan (100000cycles). An anion-cation hybrid charge storage mechanism is elucidated for superstructure cathode, which entails alternate physical uptake of Zn2+/CF3SO3 - at electroactive pores and bipedal chemical binding of Zn2+ to electronegative carbonyl/pyridine motifs. This work expands the design landscape of carbon superstructures for advanced energy storage.

Polypyrrole polymerized by iodine oxidation for zinc[sbnd]iodine batteries with high stability

Currently, aqueous rechargeable zinc-iodine (ZnI2) batteries are recognized as promising new energy storage devices due to their significant advantages, including large theoretical capacity, rapid charging and discharging capabilities and high safety. However, the shuttle effect caused by the soluble polyiodide ions leads to low utilization of active iodine and coulombic efficiency (CE). Herein, we use a high-concentration iodine solution as the oxidizing agent to synthesize polypyrrole (PPy/I2) for the first time. Compared with the PPy polymerized by using FeCl3 as oxidant (PPy/FeCl3), the ZnI2 battery based on PPy/I2 cathode demonstrates an extended cycle life (84.2 % after 3800 cycles at 2.0 A g−1), high CE (>98 % at 1.0 A g−1), and minimal self-discharge (75 % after rest 12 h). The results based on electrochemical testing and characterization indicate that the exceptional performance of PPy/I2 is primarily attributed to the early insertion of iodine species during the preparation process. This insertion creates reserved space for polyiodide ions, and the positive charge on the main chains of PPy effectively restricts their shuttle during battery operating. Furthermore, due to the ideal shuttle inhibition of PPy/I2, the Zn corrosion caused by polyiodide ions is effectively inhibited. The detailed characterizations explore the charge storage mechanism of PPy/I2. This research has guiding significance for improving the performance of PPy-based ZnI2 batteries.