Multi-electron Transfer Reactions Research Articles

High-energy and durable aqueous Zn batteries enabled by multi-electron transfer reactions

High-energy and durable aqueous Zn batteries enabled by multi-electron transfer reactions

Symmetric Catalyst Design Employing Ir Nanoparticles on Black WO3- x Nanofiber Support for Boosting Water Electrolysis.

The efficient evolution of gaseous hydrogen and oxygen from water is required to realize sustainable energy conversion systems. To address the sluggish kinetics of the multielectron transfer reaction, bifunctional catalyst materials for both the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) should be developed. Herein, a tailored combination of atomically minimized iridium catalysts and highly conductive black WO3- x nanofiber supports are developed for the bifunctional electrolyzer system. Atomic Ir catalysts, particularly those that activate the OER, minimize the utilization of precious metals. The oxygen-deficient black WO3- x NF support, which boosts the HER, offers increased electronic conductivity and favorable nucleation sites for Ir loading. The Ir-black WO3- x NFs exhibit increased double-layer capacitance, a significantly reduced onset potential, lower Tafel slope, and stable cyclability for both the OER and HER, compared to large-sized Ir catalysts loaded on white WO3 nanofibers. This study offers a strategy for developing an optimal catalyst material with suitable supports for high-performance and economical water electrolysis systems for achieving carbon-negative targets.

Halogen-powered static conversion chemistry.

Halogen-powered static conversion batteries (HSCBs) thrive in energy storage applications. They fall into the category of secondary non-flow batteries and operate by reversibly changing the chemical valence of halogens in the electrodes or/and electrolytes to transfer electrons, distinguishing them from the classic rocking-chair batteries. The active halide chemicals developed for these purposes include organic halides, halide salts, halogenated inorganics, organic-inorganic halides and the most widely studied elemental halogens. Aside from this, various redox mechanisms have been discovered based on multi-electron transfer and effective reaction pathways, contributing to improved electrochemical performances and stabilities of HSCBs. In this Review, we discuss the status of HSCBs and their electrochemical mechanism-performance correlations. We first provide a detailed exposition of the fundamental redox mechanisms, thermodynamics, conversion and catalysis chemistry, and mass or electron transfer modes involved in HSCBs. We conclude with a perspective on the challenges faced by the community and opportunities towards practical applications of high-energy halogen cathodes in energy-storage devices.

Carbon-based synergistic catalysis with transition metal dichalcogenides for electrocatalytic oxygen evolution/reduction

Oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are considered as two of the most critical processes in various renewable energy systems, including multi-electron transfer reactions. However, the kinetics of ORR/OER are usually sluggish, significantly impeding their related applications. This review article summarizes the research advancements in electrocatalytic ORR/OER achieved using traditional noble metals, transition metal dichalcogenides (TMDCs), and carbon-based materials. Exploring diverse engineering strategies, such as defect engineering, strain engineering, and alloying, takes full advantage of the inherent energy band tunability of TMDCs and the advantages of carbon materials, including tunable specific surface area, high conductivity, and good stability. These strategies aim to regulate the intrinsic activity of materials and boost the apparent activity of the electrocatalytic ORR/OER. Finally, the challenges and prospects along this research line are proposed.

Realizing high-performance glucose sensing in sweat: Synergistic use of nickel oxide nanosheets as photoelectrodes and the masking effect of Mo-POM for photoelectrochemical detection

The detection of blood glucose plays a crucial role in clinical practice, and the innovative use of sweat as a substitute for blood has brought significant practical value in the detection of blood glucose. However, lactic acid (LA) has been found to be the main interfering substance on the detection of glucose in sweat. In this study, a photoelectrochemical sensing system was constructed by using NiO nanosheets as photosensitive materials and molybdenum-based polyoxometalate clusters (Mo-POM) as masking agents. Mo-POM, an ideal electron-capturing agent, effectively promoted the spatial separation of photo-generated charge carriers in NiO nanosheets, thereby enhancing the oxidation rate of glucose on the valence band of NiO and significantly improving the detection sensitivity. Mo-POM also exhibited the characteristics of an electron sponge, facilitating fast and reversible multi-electron transfer reactions and effectively masking certain redox substances, especially lactic acid, thus greatly enhancing the selectivity of the glucose sensor. The photoelectrochemical (PEC) sensor constructed using Mo-POM has excellent sensing capability with high sensitivity to detect glucose at a minimum concentration of 1 nM. The detection limit of the sensor is 0.33 nM (S/N = 3). This sensor can be reliably applied to the detection of glucose in sweat and the accuracy of the results was verified by gas chromatography-mass spectrometry.

Na3VMn0.5Ti0.5(PO4)3/C with active Na+ hopping sites for high-rate and durable sodium-ion batteries

This study established the carbon-coated Na3VMn0.5Ti0.5(PO4)3/C (NVMTP/C) as a high-energy cathode material of the NASICON family for next-generation sodium-ion batteries (SIBs). When subjected to electrochemical sodium storage testing, the NVMTP/C cathode provided a stable specific capacity of 160.3 mAh g-1 with three electron reactions (average working voltage ∼3.4 V) during the Na+ (de)insertion routine, achieving a superior energy output of 544 Wh kg−1 among the NASICON family of SIBs. Benefiting from the characteristic NASICON structure and established multiple redox couples, the cathode delivered excellent rate capability (82 mAh g-1 at 17 C, 1 C = 176 mAh g-1), in addition to excellent cycling permanence at low and high current surges (104 mAh g-1 after 500 cycles at 0.85 C and 84 mAh g-1 after 3000 cycles at 11.34 C, respectively). Computational studies based on first principle calculations and density of states (DoS) attributed the superior electrochemical properties of NVMTP/C cathode to its substantial Na+ hopping sites facilitating the unhindered multi-electron transfer reactions (V2+/3+, V3+/4+, Ti3+/4+, and V4+/5+) reversibly at their respective redox potentials. The detailed DoS analysis revealed that the varying electronic configuration due to the co-swapping of Ti and Mn significantly uplifts the electronic conductivity of the NVMTP/C cathode. Further calculation studies clearly indicate lower activation energy for active Na+ hopping and hence faster Na-diffusion thus suggesting that the present NVMTP/C cathode can have definite commercial prospects.

Unlocking the multi-electron transfer reaction in NASICON-type cathode materials

The growing concern about scarcity and large-scale applications of lithium resources has attracted efforts to realize cost-effective phosphate-based cathode materials for next-generation Na-ion batteries (NIBs). In previous work, a series of materials (such as Na4Fe3(PO4)2(P2O7), Na3VCr(PO4)3, Na4VMn(PO4)3, Na3MnTi(PO4)3, Na3MnZr(PO4)3, etc) with ∼120 mAh g−1 specific capacity and high operating potential has been proposed. However, the mass ratio of the total transition metal in the above compounds is only ∼22 wt%, which means that one-electron transfer for each transition metal shows a limited capacity (the mass ratio of Fe is 35.4 wt% in LiFePO4). Therefore, a multi-electron transfer reaction is necessary to catch up to or go beyond the electrochemical performance of LiFePO4. This review summarizes the reported NASICON-type and other phosphate-based cathode materials. On the basis of the aforementioned experimental results, we pinpoint the multi-electron behavior of transition metals and shed light on designing rules for developing high-capacity cathodes in NIBs.

Electrochemical and spectroelectrochemical characterizations of phthalocyanines bearing peripherally tetra-4-carboxyethylenephenoxy anchoring groups and usage as photosensitizers of dye-sensitized solar cell

A series of metal-free and metallo phthalocyanines (MPc) peripherally substituted with tetra-4-carboxyethylenephenoxy (M = 2H+ (H2Pc), Co2+ (CoPc), Zn2+ (ZnPc), and TiO2+ (TiOPc)) are used as dyes in the dye-sensitized solar cells (DSSCs). To predict the feasibility of MPcs as photosensitizers, electrochemical and in-situ spectroelectrochemical characterizations are first carried out since their redox mechanisms and optical responses under electrochemical excitations are the key factor for the requirement of the photosensitizers in DSSCs. The redox activities and opto-electrochemical responses of the compounds make them promising dye candidates with electrochemically reversible and multi-electron electron transfer reactions and suitable HOMO-LUMO band positions. The DSSCs using TiO2 film modified with these MPcs are developed and characterized. DSSC analyses indicate that especially H2Pc and TiOPc among the MPcs illustrate better photovoltaic performances than the others. The increase in efficiency of DSSC consisting of H2Pc and TiOPc is mainly associated with their suitable band positions and high electron lifetimes. When compared with the Pc bearing various substituents, ethylenephenoxy linkers between the Pc ring and the carboxyl anchoring groups significantly enhance the push-pull features between the dyes and TiO2 semiconductor, which results in 1.15, 2.98, 3.17 and 3.97 % power conversion efficiencies with CoPc, ZnPc, H2Pc, and TiOPc based DSSCs respectively.

Theoretical and Experimental Study of the Crystal Orientation Effect of the Anode on the Aluminum-Air Battery Performance

The electrochemical characteristics of aluminum (Al) anodes in Al-air battery according to crystal orientation were theoretically and experimentally evaluated to analyze this phenomenon in detail. Density functional theory (DFT) calculations were performed on the open-circuit potential of the aluminum (111) plane and (100) plane in an alkaline solution. The theoretical values were obtained by DFT calculations when considering the surrounding environment and single-electron transfer. The open-circuit potentials calculated by DFT were similar to the measured potentials. These results indicate that the difference between the potential predicted by bulk thermodynamics and the potential obtained from the stepwise mechanism is related to the free energy asymmetry of the intermediate in the multi-electron transfer reaction and the chemical stabilization of the surrounding environment during the product formation. The crystal orientation affects the performance of Al-air battery by the above effects. Al (100) showed the highest output power depending on the orientation effect in the discharge test result and the I-P curve.

Accumulation of Four Electrons on a Terphenyl (Bis)disulfide.

The activation of N2 , CO2 or H2 O to energy-rich products relies on multi-electron transfer reactions, and consequently it seems desirable to understand the basics of light-driven accumulation of multiple redox equivalents. Most of the previously reported molecular acceptors merely allow the storage of up to two electrons. We report on a terphenyl compound including two disulfide bridges, which undergoes four-electron reduction in two separate electrochemical steps, aided by a combination of potential compression and inversion. Under visible-light irradiation using the organic super-electron donor tetrakis(dimethylamino)ethylene, a cascade of light-induced reaction steps is observed, leading to the cleavage of both disulfide bonds. Whereas one of them undergoes extrusion of sulfur to result in a thiophene, the other disulfide is converted to a dithiolate. These insights seem relevant to enhance the current fundamental understanding of photochemical energy storage.

(Invited) Integrating Material Design, in-Operando Spectroscopy and Device Testing for Next Generation Lithium-Sulfur Batteries

Rechargeable batteries with conversion type electrodes are attractive due to their ability to achieve higher capacity through multi-electron transfer reactions. Elemental sulfur is one of the most interesting materials amongst all conversion-based cathodes because of its high theoretical capacity (~1675 mAh/g – 5-10-fold higher than Li-ion batteries), natural abundance, non-toxicity, and cost-effectiveness. In this talk, I will provide glimpses of our group’s research on integrating material design and fabrication, in-operando and postmortem spectroscopy, and device assembly and testing (coin/pouch) to study and develop next generation lithium-sulfur batteries. In particular, I will discuss our projects on studying cathode chemistries to first mitigate polysulfide shuttle via host-polysulfide interactions followed by tailoring of S redox to trigger single plateau behavior for long-term cycle stability.

Heterostructures based on transition metal chalcogenides and layered double hydroxides for enhanced water splitting

Heterostructure engineering, as a strategy to overcome the limitation of single component activity, e.g., transition metal chalcogenides (TMCs) or layered double hydroxides (LDHs), and improve the electrocatalytic performance of multi-electron charge transfer reactions is reviewed. The main mechanism of heterostructure engineering is briefly described, and selected examples are given to investigate the contribution of synergistic effects of such heterostructure to improve water splitting. Heterostructure engineering, based on transition metal chalcogenides (TMCs) and layered double hydroxides (LDHs), is regarded as an efficient strategy to improve the overall kinetics of water splitting, i.e., OER and HER processes. The synergistic effect of the two components in a well-designed heterostructure, plays a key role in improving electrocatalysis with a decrease of the overpotential. • Correlation between structural-electronic properties and electrochemical performance of TMCs and LDHs hybrid is described. • This review illustrates the role of surface electronic configuration of TMCs and LDHs towards electrocatalysis kinetics. • The synergistic effect of heterostructure engineering favors for the water electrocatalysis.

Multipurpose Solar Photoelectrochemical Hybrid Multilayer Films Based on Porphyrin and Preyssler Type Polyoxometalates for Solar Cell and Ag Nanomaterial Synthesis

Multilayer films with electrostatic interaction between Preyssler,s Polyanions (NH4)14[NaP5W30O110]14- .31H2O and tetracationic free base porphyrin [H2TN+(Me)3PyP]4+ have been alternately deposited on quartz and ITO substrates. and characterized by UV-visible absorption spectroscopy to follow the successive deposition of multilayer film. Solution phase interaction of both components revealed the stiochiometric ratio of the electrostatic complex formed . The morphology and composition of films were studied by atomic force microscopy and X-ray photoelectron spectroscopy (XPS ) .While permeability to cations in aqueous media and redox behavior were studied by cyclic voltametry . The solar photoctalytic activity of hybrid films is identified by TEM images obtained after heterogeneous aqueous photoreduction of Ag2SO4(aq) and KAuCl4 (aq) to yield diversified nanostructures . The study is first and initial report on preyssler type polyanions and porphyrin based heterogenous photocatalysis that provide a green, solar and multiple applications for precious metal recovery as nanoparticle ,sustainable wastewater purification and solar photocurrent generation.Polyoxometalates (POMs) are metal−oxygen framework of early metal elements in their highest oxidation state , able to undergo reversible, stepwise, multielectron-transfer reactions, which are the basis for many catalytic processes[1].These polyanions clusters exhibit applications in catalysis, medicine, materials science [2]. They offer effective photocatalytic properties in oxidation and reduction processes. On photolysis, the high oxidizing ability of excited POMs can lead to the degradation of a variety of organic compounds such as pollutants, leading to a process for water purification [3]. In the presence of a sacrificial electron donor , their photolysis lead to the formation of reduced POMs which can in turn reduce metallic ions. It could be a good alternative for precious metals recovery or synthesis of metal nanoparticles. [4,5]. However, polyoxometalates absorb in the uv part of spectrum, thus they require UV excitation, which cease its large-scale environmental application. One of obvious strategy is to couple it with some chromophore group which can be sensitized by visible light. Metal porphyrins are attractive components in materials because of their appealing chemical and photochemical properties: high stability, intense visible absorption bands, long-lived excited states, and tunability by chemical derivatization [2]. Figure 1.1 R.H.S. Representation of the porphyrin used 5, 10, 15, 20-Tetrakis (4-trimethylammoniophenyl) porphyrin tetra(p-toluenesulfonate), namely [H2TN+(Me)3PyP]4+) used with the Preyssler type (NH4)14[NaP5W30O110]14- .31H2O . L.H.S. UV-visible record on quartz and ITO shows layer by layer absorbance. Formation of Multilayer Films :H2TN+(Me)3PyP4+] / [(NH4)14[NaP5W30O110]14- .31H2O ] The alternate deposition of positively charged porphyrin, H2TN+(Me)3PyP4+, and negatively charged [NaP5W30O110]14-on slides of quartz and Indium tin Oxide (ITO) lectrodes by layer-by-layer were performed.

Cooperative electrocatalytic effect of Pd and Ce alloys nanoparticles in PdCe@CNWs electrode for oxygen evolution reaction (OER)

Electrocatalytic water oxidation is an ecofriendly and intelligent approach for oxygen evolution from water because it requires only water and electrical potential/energy as inputs. However, the oxygen evolution reaction (OER) is the most challenging multi-electron and proton transfer reaction during water electrolysis for hydrogen production. The electrocatalyst is the critical component that controls the efficiency of oxygen evolution. Therefore, it is essential to explore efficient and durable electrocatalysts that must have significant efficiency compared to the benchmark catalyst (i.e., RuO2) for OER. Herein, self-supported carbon nanowires (CNWs) decorated with bimetallic palladium-cerium PdCe alloys nanoparticles (NPs) were synthesized through an electrospinning-thermal carbonation approach to overcome the kinetic barriers and deliver decent alkaline OER activity. As a result, the PdCe/CNWs requires a low overpotential of ∼360 and ∼450 mV vs. RHE to deliver the current density of 10 and 50 mA/cm2 with low Tafel slope (62 mV/dec) for OER, which is even comparable to the benchmark, RuO2 (360 mV and 73 mV/ dec). Notably, only a slight increase (∼ 10 %) in overpotential was observed after 10,000 cycles indicating high electrocatalyst stability. The high stability and improved OER performance of the PdCe/CNWs electrode can be explained by the cooperative catalytic influence between Pd, Ce, and C species.

Unique Electronic Excitations at Highly Localized Plasmonic Field.

ConspectusUnder visible light illuminations, noble metal nanostructures can condense photon energy into the nanoscale region. By precisely tuning the metal nanostructures, the ultimate confinement of photoenergy at the molecular scale can be obtained. At such a confined photon energy field, various unique photoresponses of molecules, such as efficient visible light energy conversion processes or efficient multielectron transfer reactions, can be observed. Light-matter interactions also increase with the condensation of photons with nanoscale regions, leading to efficient light energy utilizations. Moreover, the strong field confinement can often modulate electronic excitations beyond normal selection rules. Such unique electronic excitations could realize innovative photoenergy conversion systems. On the other hand, such interactions lead to changes in the optical absorption property of the system via the formation of hybridized electronic energy states. This hybridized state is expected to have the potential to modulate the chemical reaction pathways. Taking these facts into consideration, a probe for the molecular absorption process with high sensitivity allows us to find novel ways for further precise tuning of light-matter interactions. In this Account, we review phenomena of unique electronic excitations from the perspective of our previous investigations using surface-enhanced Raman scattering (SERS) spectroscopy at electrified interfaces. Because the enhancement mechanism of Raman scattering at interfaces is deeply correlated with the photon absorption process accompanied by the electronic excitations between molecules and electrode surfaces, the detailed SERS investigations of the well-defined system can provide information on the electronic excitation processes. Through SERS observations of single-molecule junctions at electrodes or well-defined low-dimensional carbon materials, we have observed the characteristic Raman bands containing additional polarization tensors, indicating the occurrence of electronic polarization induced by electronic excitations based on a distinct selection rule. The origins for the observed facts were attributed to the highly condensed electric field producing the huge intensity gradient at the nano scale. The electrochemical potential control of the system would be valuable for the control of the excitation process. Additionally, from Raman spectra of dye molecules coupled to the plasmonic field, the changes in the Raman scattering intensity depending on the strength of interactions suggested the modulation of the absorption characteristics of the system. In addition, we have proved that the electrochemical potential control method can be a powerful tool for the active tuning of the light-matter interaction, leading to the change in the light absorption property. The molecular behaviors of dyes in the strong-coupling regime were reversibly tuned to show intense SERS. The current descriptions provide novel insights for these unique electronic excitations, realized by the plasmon excitation, that lead to advanced photoenergy conversions beyond the limits of present systems.

Regulating electron transfer over asymmetric low-spin Co(II) for highly selective electrocatalysis

Modulating the steric-electronic configuration of metal-organic centers is key for tuning the activity and selectivity of heterogeneous reactions, especially multi-electron transfer reactions. Here, three different asymmetric metal-organic complexes with unique steric-electronic structures are immobilized on nanocarbon for an electron-transfer-controlled oxygen reduction reaction. The strong-field ligand-induced low-spin ( LS ) Co II creates a necessary steric configuration for regulating reaction selectivity through ligand's proton transfer ability, for which acidic diamine ligands facilitate a four-electron transfer (94%), whereas basic ligands drive a highly selective two-electron route (97%). The steric-electronic regulation of the reaction selectivity at catalytic sites is characterized using X-ray absorption spectroscopy, reaction kinetic path analysis, and density functional theory calculation. Our results indicate that an LS state of Co II with asymmetric coordination is necessary to form a unique “flytrap” structure to promote O 2 capture for the subsequent proton-coupled electron transfer, which is regulated by the Brønsted acidity of coordinating ligands. • A series of asymmetric metal-organic complexes are immobilized on nanocarbons • Advanced characterizations are used to explore their structures at the atomic level • Selectivity of ORR is regulated by changing the ligand field strength of the active site • Operando X-ray spectroscopy and computational analysis confirm the reaction mechanism The majority of energy conversion processes such as hydrogen peroxide production, nitrogen fixation, and CO 2 reduction generally involve multi-electron transfer, resulting in multiple by-products and requiring tedious purification process. The development of highly selective electrocatalysts can not only reduce the energy consumption in the production process but also benefit to promote their large-scale application. Here, we report an asymmetric ligand design of molecular “Venus flytrap” at atomic Co II catalysts on a heterogeneous carbon surface for oxygen electrocatalysis with controlled selectivity. Our XAFS and DFT calculations show that the strong-field ligand-induced LS Co II centers offer inimitable steric-electronic advantages in capturing O 2 and the capability to regulate reaction pathways through an H-bonding interaction between the ligands and peroxo intermediate. The proposed concept completes the picture of designer single-atom catalyst by covering the often overlooked exterior coordination sites, and is expected to be generally applicable to other heterogeneous catalyst systems. Steric-electronic configuration regulation plays a key role in achieving highly selective electrocatalysis. As a proof of concept, a series of asymmetric metal-organic complexes were immobilized on a conductive substrate for oxygen reduction reaction (ORR). The strong-field ligand-induced low-spin cobalt sites exhibit an excellent selectivity for four-electron ORR, whereas the medium-field ligand linked Co sites display high efficiency for the two-electron reduction of oxygen into hydrogen peroxide.

Coulometric and Chronoamperometric Studies on Bisulfite Reduction at a Surfactant/Myoglobin Film on Glassy Carbon Electrode

<i>Background</i>. The redox-active protein, myoglobin (Mb), exchanges electrons very slowly with bare electrodes. Just like on a highly oriented pyrolytic graphite (HOPG) bare electrode, electron transfer between myoglobin (Mb) and a bare glassy carbon (GC) electrode was not observed. The myoglobin (Mb) in di-dodecyl dimethyl ammonium bromide (DDAB) film immobilized on glassy carbon electrode surface had a good charge transport, allowing Mb to be used as a redox catalyst for multi-electron transfer reactions. <i>Objective</i>. We report here the myoglobin on a glassy carbon (GC) electrode as a catalyst for the multi-electron reduction of bisulfite in aqueous buffered solutions. <i>Methods</i>. Coulometry and chronoamperometry are used as tools to probe the Mb/DDAB film on GC electrode as an effective electro-catalyst for the multi-electron reduction of bisulfite. <i>Results</i>. Variation in current with time of bisulfite reduction followed first-order reaction kinetics. The heterogeneous electron transfer rate constant of the film and catalytic rate constant for the reduction of bisulfite were determined. <i>Conclusion</i>. The study confirmed that bisulfite was the reactive species and the catalytic reduction reaction at Mb/DDAB film followed the EC’ catalytic mechanism.

The targeted multi-electrons transfer for acetic acid and ethanol obtained with (n-Bu4N)3SVW11O40 and in synergetic catalysis in CO2 electroreduction

Electrocatalytic CO2 reduction (ECO2RR) is a very promising new energy technology for carbon capture, utilization and storage. The chemical inertness of CO2 makes its conversion needs to be driven by efficient catalysts. Polyoxometalate (POM) inhibits hydrogen evolution side reaction (HER) for ECO2RR via proton coupling in their reversible, stepwise multi-electron transfer reactions. In this work, indium and prepared (n-Bu4N)3SVW11O40 (SVW11) work as synergetic catalysis firstly for ECO2RR to acetic acid and ethanol with 67.4% and 19.4%, respectively. The provided electron transferred to vanadium center in SVW11 and In3+ leading to the activity of In recovered and HSVIVW11O403− formed, where the proton-coupled electron transfer step of VIV/V in SVW11 electrolyte promoted the process of ECO2RR. The isomerized POM effectively reducing the reaction overpotential and increasing the products selectivity also.

Keggin型ポリオキソタングステートの合成経路に関する研究

Synthetic pathways of Keggin-type polyoxotungstates (POTs), which are expected to catalyze multi-electron transfer reactions, were investigated by first-principles calculations. The reaction pathways for the formation of new Keggin-type POTs from existing ones via ion exchange were explored by the Nudged Elastic Band (NEB) method, and the effects of the kind of heteroatom and the relative permittivity of the solvent were discussed.

Insight into the coordinating mechanism of multi-electron reaction and structural stability induced by K+ pre-intercalation for magnesium ions batteries

Multi-electron reaction as the appealing alternative can offer higher specific capacity, however, it delivers a tendency to collapse the structure causing cycling instability. Herein, K+ pre-intercalation strategy is applied to modify VS4/N-TG as cathode for MIBs. As opposed to the structural breakdown caused by multi-electron reaction, pre-intercalated K+ not only modulate electronic state, making V2+ present as instead of partial V4+ achieving multi-electron reaction, but also act as pillar ions for coordinating the interaction of guest-ions with adjacent host ions to strengthen the framework to maintain structural stability, therefore, K0.20VS4/N-TG delivers high specific capacity of 190 mAh g–1, and excellent cycling stability with about near 100% capacity retention after 2000 cycles. This finding gives insights into enabling multi-electron transfer reaction while achieving high structural stability via K+ pre-intercalation, shed light on designing viable multi-electron reaction in intercalation type cathode without destroying stable structure for high performance magnesium ions batteries.