Cryoactivated proton-involved redox reactions enable stable-cycling fiber cooper metal batteries operating at-50℃

Fiber-shaped batteries that feature outstanding flexibility,light weight,and wovenability are extremely attractive for powering smart wearable electronic textiles,which further stimulates their demand in extreme environments.However,there are rare reports on ultralow-temperature fiber batteries to date.This is mainly attributed to the poor conductivity of electrodes and freezing of electrolytes that restrain their satisfactory flexible operation in cold environments.Herein,we propose a fiber cooper metal battery consisting of a conductive polyaniline cathode,an anti-freezing Cu(BF4)2+H3PO4electrolyte and an acidresistant copper wire anode,which can withstand various deformations at ultralow temperatures.Impressively,enhanced capacity and cyclic stability can be achieved by cryoactivated abundant reactive sites in the polyaniline,while benefiting from redox reactions with rapid kinetics involving protons rather than copper ions.Consequently,this well-designed polyaniline/Cu fiber battery delivers excellent flexibility without obvious capacity decay after being bent at-30℃,as well as a remarkable discharge capacity of 120.1 mA h g-1and a capacity retention of 96.8%after 2000 cycles at-50℃.The fiber batteries integrated into wearable textiles can power various electronic devices.These performances greatly outperform those of most reported works.Overall,this work provides a promising strategy toward applications of cryogenic wearable energy storage devices.

Deciphering the Oxygen Absorption Pre-edge: A Caveat on its Application for Probing Oxygen Redox Reactions in Batteries

The pre-edges of oxygen-K X-ray absorption spectra have been ubiquitous in transition metal(TM)oxide studies in various fields,especially on the fervent topic of oxygen redox states in battery electrodes.However,critical debates remain on the use of the O-K pre-edge variations upon electrochemical cycling as evidences of oxygen redox reactions,which has been a popular practice in the battery field.This study presents an investigation of the O-K pre-edge of 55 oxides covering all 3d TMs with different elements,structures,and electrochemical states through combined experimental and theoretical analyses.It is shown unambiguously that the O-K pre-edge variation in battery cathodes is dominated by changing TM-d states.Furthermore,the pre-edge enables a unique opportunity to project the lowest unoccupied TM-d states onto one common energy window,leading to a summary map of the relative energy positions of the low-lying TM states,with higher TM oxidation states at lower energies,corresponding to higher electrochemical potentials.The results naturally clarify some unusual redox reactions,such as Cr^(3+/6+).This work provides a critical clarification on O-K pre-edge interpretation and more importantly a benchmark database of O-K pre-edge for characterizing redox reactions in batteries and other energy materials.

Understanding synergistic catalysis on Pt–Cu diatomic sites via operando X-ray absorption spectroscopy in sulfur redox reactions

Sulfur redox reactions render lithium–sulfur(Li–S)batteries with an energy density of>500Whkg−1 but suffer a low practical capacity and fast capacity fade due to sluggish sulfur redox reaction(SRR)kinetics,which lies in the complex reaction process that involves a series of reaction intermediates and proceeds via a cascade reaction.Here,we present a Pt–Cu dual-atom catalyst(Pt/Cu-NG)as an electrocatalyst for sulfur redox reactions.Pt/Cu-NG enabled the rapid conversion of soluble polysulfide intermediates into insoluble Li2S2/Li2S,and consequently,it prevented the accumulation and shuttling of lithium polysulfides,thus outperforming the corresponding single-atom catalysts(SACs)with individual Pt or Cu sites.Operando X-ray absorption spectroscopy and density functional theory calculations revealed that a synergistic effect between the paired Pt and Cu atoms modifies the electronic structure of the Pt site through d-orbital interactions,resulting in an optimal moderate interaction of the metal atom with the different sulfide species.This optimal interaction enhanced charge transfer kinetics and promoted sulfur redox reactions.Our work thus provides important insights on the atomic scale into the synergistic effects operative in dual-atom catalysts and will thus pave the way to electrocatalysts with enhanced efficiency for high-performance Li–S batteries.

Catalytically altering the redox pathway of sulfur in propylene carbonate electrolyte using dual-nitrogen/oxygen-containing carbon

Carbonate electrolytes are one of the most desirable electrolytes for high-energy lithium-sulfur batteries(LSBs)because of their successful implementation in commercial Li-ion batteries.The low-polysulfide-solubility feature of some carbonate solvents also makes them very promising for overcoming the shuttle effects of LSBs.However,regular sulfur electrodes experience undesired electrochemical mechanisms in carbonate electrolytes due to side reactions.In this study,we report a catalytic redox mechanism of sulfur in propylene carbonate(PC)electrolyte based on a compari-son study.The catalytic mechanism is characterized by the interactions between polysulfides and dual N/O functional groups on the host carbon,which largely prevents side reactions between polysulfides and the carbonate electrolyte.Such a mechanism coupled with the low-polysulfide-solubility feature leads to stable cycling of LSBs in PC electrolyte.Favorable dual N/O functional groups are identified via a density functional theory study.This work provides an alternative route for enabling LSBs in carbonate electrolytes.

Achieving asymmetric redox chemistry for oxygen evolution reaction through strong metal-support interactions

Water electrolysis poses a significant challenge for balancing catalytic activity and stability of oxygen evolution reaction(OER)electrocatalysts.In this study,we address this challenge by constructing asymmetric redox chemistry through elaborate surface OO–Ru–OH and bulk Ru–O–Ni/Fe coordination moieties within single-atom Ru-decorated defective NiFe LDH nanosheets(Ru@d-NiFe LDH)in conjunction with strong metal-support interactions(SMSI).Rigorous spectroscopic characterization and theoretical calculations indicate that single-atom Ru can delocalize the O 2p electrons on the surface and optimize d-electron configurations of metal atoms in bulk through SMSI.The^(18)O isotope labeling experiment based on operando differential electrochemical mass spectrometry(DEMS),chemical probe experiments,and theoretical calculations confirm the encouraged surface lattice oxygen,stabilized bulk lattice oxygen,and enhanced adsorption of oxygen-containing intermediates for bulk metals in Ru@d-NiFe LDH,leading to asymmetric redox chemistry for OER.The Ru@d-NiFe LDH electrocatalyst exhibits exceptional performance with an overpotential of 230 mV to achieve 10 mA cm^(−2)and maintains high robustness under industrial current density.This approach for achieving asymmetric redox chemistry through SMSI presents a new avenue for developing high-performance electrocatalysts and instills confidence in its industrial applicability.

M@MIL-100（Fe） （M = Au, Pd, Pt） nanocomposites fabricated by a facile photodeposition process： Efficient visible-light photocatalysts for redox reactions in water

Proper design and preparation of high-performance and stable dual functional photocatalytic materials remains a significant objective of research. In this work, highly dispersed noble-metal nanoparticles （Au, Pd, Pt） were immobilized on MIL-100（Fe） （denoted M@MIL-100（Fe）） using a facile room-temperature photodeposition technique. The resulting M@MIL-100（Fe） （M = Au, Pd, and Pt） nanocomposites exhibited enhanced photoactivities toward photocatalytic degradation of methyl orange （MO） and reduction of heavy-metal Cr（VI） ions under visible-light irradiation （A ≥ 420 nm） compared with blank-MIL-100（Fe）. Combining these results with photoelectrochemical analyses revealed that noble-metal deposition can effectively improve the charge-separation efficiency of MIL-100（Fe） under visible-light irradiation. This phenomenon in turn leads to the enhancement of visible-light-driven photoactivity of M@MIL-100（Fe） toward photocatalytic redox reactions. In particular, the Pt@MIL-100（Fe） with an average Pt particle size of 2 nm exhibited remarkably enhanced photoactivities compared with those of M@MIL-100（Fe） （M = Au and Pd）, which can be attributed to the integrative effect of the enhanced light absorption intensity and more efficient separation of the photogenerated charge carrier. In addition, possible photocatalytic reaction mechanisms are also proposed.

Nanomedicine-Leveraged Intratumoral Coordination and Redox Reactions of Dopamine for Tumor-Specific Chemotherapy

Great efforts have been made in investigating the neurotoxicity of dopamine(DA)in the presence of manganous ions.In contrast,here,we probe the possibility of DA-based cancer chemotherapy by leveraging intratumoral redox reactions of DA for producing cytotoxic species in situ.For this purpose,we have constructed a Mn-engineered,DA-loaded nanomedicine.Based on the unique size effect of the nanocarrier,this nanomedicine will not enter the central nervous system but can effectively accumulate in the tumor region,after which the nanocarrier can degrade to release Mn^(2+)and DA in response to the mild acidic intracelluar microenvironment of cancer cells.DA can chelate Mn^(2+)to form a binary coordination complex,where the strong metal-ligand interaction significantly promotes electron delocalization and elevates the reducibility of Mn center,favoring two sequential one-electron oxygen reduction reactions forming H_(2)O_(2),which can be further converted into highly oxidizing ·OH under the cocatalysis by Mn^(2+)and intracellular Fe^(2+).Additionally,as a twoelectron oxidation product of DA ligand,DA-oquinone is potent in exhausting cellular sulfhydryl and depleting reduced glutathione,inhibiting the intrinsic antioxidative mechanism of cancer cells,finally triggering severe oxidative damages in a synergistic manner.It is expected that such a strategy of nanotechnology-mediated metal-ligand coordination and subsequent nontoxicity-to-toxicity transition of DA in tumor may provide a promising prospect for future chemotherapy design.

A cascade of redox reactions in the biosynthesis of the protein phosphatase-2A inhibitor rubratoxin A

Subject Code:H30 With the support by the National Natural Science Foundation of China,a collaborative study by the research groups led by Prof.Hu Youcai(胡友财),Prof.Yu Shishan(庾石山)and Prof.Tang Yi(唐奕)from the State Key Laboratory of Bioactive Substance and Function of Natural Medicines,Institute

High-capacity lithium-rich cathode oxides with multivalent cationic and anionic redox reactions for lithium ion batteries

Lithium-rich cathode oxides with capability to realize multivalent cationic and anionic redox reactions have attracted much attention as promising candidate electrode materials for high energy density lithium ion batteries because of their ultrahigh specific capacity. However, redox reaction mechanisms, especially for the anionic redox reaction of these materials, are still not very clear. Meanwhile, several pivotal challenges associated with the redox reactions mechanisms, such as structural instability and limited cycle life, hinder the practical applications of these high-capacity lithium-rich cathode oxides. Herein, we review the lithium-rich oxides with various crystal structures. The multivalent cationic/anionic redox reaction mechanisms of several representative high capacity lithium-rich cathode oxides are discussed, attempting to understand the origins of the high lithium storage capacities of these materials. In addition, we provide perspectives for the further development of these lithium-rich cathode oxides based on multivalent cationic and anionic redox reactions, focusing on addressing the fundamental problems and promoting their practical applications.

Robust interface layers with redox shuttle reactions suppress the dendrite growth for stable solid-state Li metal batteries

Designing a durable lithium metal anode for solid state batteries requires a controllable and uniform deposition of lithium, and the metal lithium layer should maintain a good interface contact with solid state electrolyte during cycles. In this work, we construct a robust functional interface layer on the modified LiB electrode which considerably improves the electrochemical stability of lithium metal electrode in solid state batteries. It is found that the functional interface layer consisting of polydioxolane, polyiodide ion and Li TFSI effectively restrains the growth of lithium dendrites through the redox shuttle reaction of I-/I3-and maintains a good contact between lithium anode and solid electrolyte during cycles. Benefit from these two advantages, the modified Li-B anode exhibits a remarkable cyclic performance in comparison with those of the bare Li-B anode.

Nanoscale transition metal catalysts anchored on perovskite oxide enabling enhanced kinetics of lithium polysulfide redox in lithium-sulfur batteries

To obtain high-performance lithium-sulfur(Li-S)batteries,it is necessary to rationally design electrocatalytic materials that can promote efficient sulfur electrochemical reactions.Herein,the robust heterostructured material of nanoscale transition metal anchored on perovskite oxide was designed for efficient catalytic kinetics of the oxidation and reduction reactions of lithium polysulphide(Li PSs),and verified by density functional theory(DFT)calculations and experimental characterizations.Due to the strong interaction of nanoscale transition metals with Li PSs through chemical coupling,heterostructured materials(STO@M)(M=Fe,Ni,Cu)exhibit excellent catalytic activity for redox reactions of Li PSs.The bifunctional heterostructure material STO@Fe exhibits good rate performance and cycling stability as the cathode host,realizing a high-performance Li-S battery that can maintain stable cycling under rapid charge-discharge cycling.This study presents a novel approach to designing electrocatalytic materials for redox reactions of Li PSs,which promotes the development of fast charge-discharge Li-S batteries.

Unexpected Li displacement and suppressed phase transition enabling highly stabilized oxygen redox in P3-type Na layered oxide cathode

Oxygen redox is considered a new paradigm for increasing the practical capacity and energy density of the layered oxide cathodes for Na-ion batteries. However, severe local structural changes and phase transitions during anionic redox reactions lead to poor electrochemical performance with sluggish kinetics.Here, we propose a synergy of Li-Cu cations in harnessing the full potential of oxygen redox, through Li displacement and suppressed phase transition in P3-type layered oxide cathode. P3-type Na_(0.7)[Li_(0.1)Cu_(0.2)Mn_(0.7)]O_(2) cathode delivers a large specific capacity of ~212 mA h g^(-1)at 15 mA g^(-1). The discharge capacity is maintained up to ~90% of the initial capacity after 100 cycles, with stable occurrence of the oxygen redox in the high-voltage region. Through advanced experimental analyses and first-principles calculations, it is confirmed that a stepwise redox reaction based on Cu and O ions occurs for the charge-compensation mechanism upon charging. Based on a concrete understanding of the reaction mechanism, the Li displacement by the synergy of Li-Cu cations plays a crucial role in suppressing the structural change of the P3-type layered material under the oxygen redox reaction, and it is expected to be an effective strategy for stabilizing the oxygen redox in the layered oxides of Na-ion batteries.

Hierarchical CoFe@N-Doped Carbon Decorated Wood Carbon as Bifunctional Cathode in Wearable Zn-Air Battery

Rechargeable Zn-air batteries(ZAB)have drawn extensive attention due to their eco-friendliness and safety.However,the lack of high-performance and low-cost oxygen redox reactions(OER and ORR)catalysts has become one of the main stumbling blocks in their development.Herein,we successfully fabricate a CoFe nanobubble encapsulated in nitrogen-doped carbon nanocage on wood carbon support(CoFe@NC/WC)via pyrolysis of a novel Prussian blue analog(PBA)/spruce precursor.The hierarchical CoFe@NC/WC catalyst exhibits an excellent potential difference of 0.74 V between the OER potential at 10 mA cm^(-2)and half-wave potential of ORR in 0.1 M KOH,comparable to recently reported preeminent electrocatalysts.Further,CoFe@NC/WC shows outstanding electrochemical performance in liquid ZAB,with a peak power density of 138.9 mW cm^(-2)and a specific capacity of 763.5 mAh g^(-1).More importantly,a bacterial cellulose nanofiber reinforced polyacrylic acid(BC-PAA)hydrogel electrolyte shows ultrahigh tensile-breaking stress of 1.58 MPa.In conjunction with the as-prepared CoFe@NC/WC catalyst,BC-PAA-based wearable ZAB displays impressive rechargeability and foldability,and can power portable electronics,such as electronic timer and mobile phone,in bent states.This work provides a new approach toward high-activity and low-cost catalysts for ZAB.

Understanding Sulfur Redox Mechanisms in Different Electrolytes for Room-Temperature Na-S Batteries

This work reports influence of two different electrolytes,carbonate ester and ether electrolytes,on the sulfur redox reactions in room-temperature Na-S batteries.Two sulfur cathodes with different S loading ratio and status are investigated.A sulfur-rich composite with most sulfur dispersed on the surface of a carbon host can realize a high loading ratio(72%S).In contrast,a confined sulfur sample can encapsulate S into the pores of the carbon host with a low loading ratio(44%S).In carbonate ester electrolyte,only the sulfur trapped in porous structures is active via‘solid-solid’behavior during cycling.The S cathode with high surface sulfur shows poor reversible capacity because of the severe side reactions between the surface polysulfides and the carbonate ester solvents.To improve the capacity of the sulfur-rich cathode,ether electrolyte with NaNO_(3) additive is explored to realize a‘solid-liquid’sulfur redox process and confine the shuttle effect of the dissolved polysulfides.As a result,the sulfur-rich cathode achieved high reversible capacity(483 mAh g^(−1)),corresponding to a specific energy of 362 Wh kg^(−1) after 200 cycles,shedding light on the use of ether electrolyte for high-loading sulfur cathode.

Modulation on electrostatic potential to build a firm bridge at NiO_(x)/perovskite interface for efficient and stable perovskite solar cells

The NiO_(x)/perovskite interface in NiO_(x)-based inverted perovskite solar cells(PSCs)is one of the main issues that restrict device performance and long-term stability,as the unwanted interfacial defects and undesirable redox reactions cause severe interfacial non-radiative recombination and open-circuit voltage(Voc)loss.Herein,a series of self-assembled molecules(SAMs)are employed to bind,bridge,and stabilize the NiO_(x)/perovskite interface by regulating the electrostatic potential.Based on systematically theoretical and experimental studies,4-pyrazolecarboxylic acid(4-PCA)is proven as an efficient molecule to simultaneously passivate the NiO_(x)and perovskite surface traps,release the interfacial tensile stress as well as quench the detrimental interface redox reactions,thus effectively suppressing the interfacial non-radiative recombination and enhancing the quality of perovskite crystals.Consequently,the PSCs with 4-PCA treatment exhibited an eminently increased Voc,leading to a significant increase in power conversion efficiency from 21.28%to 23.77%.Furthermore,the unencapsulated devices maintain 92.6%and 81.3%of their initial PCEs after storing in air with a relative humidity of 20%–30%for 1000 h and heating at 65℃for 500 h in a N_(2)-filled glovebox,respectively.

Synthesis of NO by rotating sliding arc discharge reactor with conical-spiral electrodes

The present work investigates the potential applications of nitrogen oxides(NO_(x)),particularly nitric oxide(NO)and nitrogen dioxide(NO_(2)),generated through discharge plasma in diverse sectors such as medicine,nitrogen fixation,energy,and environmental protection.In this study,a rotating sliding arc discharge reactor was initially employed to produce high concentrations of gaseous NO_(x),followed by the utilization of a molybdenum wire redox reactor for NO_(2)-to-NO conversion.The outcomes reveal that the discharge states and generations of NO_(x) are affected by varying parameters,including the applied energies,frequencies and airflow states(1.3-2.6 m/s are the laminar flow,2.6-5.2 m/s are the transition state,5.2-6.5 m/s are the turbulent flow),and the concentrations of NO_(x) within the arc discharge are higher than that in the spark discharge.Moreover,the concentrations of NO,NO_(2) and NO_(x) gradually increased,and the concentration ratios of NO/NO_(2) and NO_(x)/NO_(2) decreased with increasing the applied energy for one cycle from 14.8 mJ to 24.3 mJ.Meanwhile,the concentrations of NO,NO_(2) and NO_(x) gradually decreased,and the concentration ratios of NO/NO_(2) and NO_(x)/NO_(2) first decreased and then increased with increasing the applied frequencies from 5.0 kHz to 9.0 kHz.Further,the concentrations of NO,NO_(2) and NO_(x) gradually decreased,and the concentration ratios of NO/NO_(2) and NO_(x)/NO_(2) first increased and then decreased with increasing the air flow speeds from 1.3 m/s to 6.5 m/s.Lastly,the concentrations of NO increased and NO_(2) decreased with increasing temperature from 25℃ to 400℃ using molybdenum converted.These findings provide experimental support for the application of plasma in the fields of medicine,nitrogen fixation,energy and environmental protection.

Tuning anionic redox activity to boost high-performance sodium-storage in low-cost Na_(0.67)Fe_(0.5)Mn_(0.5)O_(2) cathode

Na-based layered iron-manganese oxide Na_(0.67)Fe_(0.5)Mn_(0.5)O_(2) containing only low-cost elements is a promising cathode for Na-ion batteries used in large-scale energy storage systems.However,the poor cycle stability restricts its practical application.The capacity decay of Na_(0.67)Fe_(0.6)Mn_(0.5)O_(2) mainly originates from the irreversible anionic redox reaction charge compensation due to the high-level hybridization between oxygen and iron.Herein,we rationally design a surface Ti doping strategy to tune the anionic redox reaction activity of Na_(0.67)Fe_(0.5)Mn_(0.5)O_(2) and improve its Na-storage properties.The doped Ti ions not only enlarge the Na migration spacing layer but also improve the structure stability thanks to the strong Ti-O bond.More importantly,the d0-shell electronic structure of Ti^(4+) can suppress the charge transfer from the oxidized anions to cations,thus reducing the anionic redox reaction activity and enhancing the reversibility of charge compensation.The modified Na_(0.67)Fe_(0.5)Mn_(0.5)O_(2) cathode shows a reversible capacity of 198 mA h g^(-1) and an increased capacity retention from 15% to 73% after about1 month of cycling.Meanwhile,a superior Na-ion diffusion kinetics and rate capability are also observed.This work advances the commercialization process of Na-based layered iron-manganese oxide cathodes;on the other hand,the proposed modification strategy paves the way for the design of high-performance electrode materials relying on anionic redox reactions.

Anionic redox reaction mechanism in Na-ion batteries

Na-ion batteries(NIBs),as one of the next-generation rechargeable battery systems,hold great potential in large-scale energy storage applications owing to the abundance and costeffectiveness of sodium resources.Despite the extensive exploration of electrode materials,the relatively low attainable capacity of NIBs hinders their practical application.In recent years,the anionic redox reaction(ARR)in NIBs has been emerging as a new paradigm to deliver extra capacity and thus offers an opportunity to break through the intrinsic energy density limit.In this review,the fundamental investigation of the ARR mechanism and the latest exploration of cathode materials are summarized,in order to highlight the significance of reversible anionic redox and suggest prospective developing directions.

Redox Reaction of Disulfide/Polyaniline in Aqueous Solution

The cleavage and formation of the di sulfide bond of 2,5-dimercapto-1,3,4-thiadiazole (DMcT) were examined in an aqueous solution of pH value from 0 to 14 with and without polyaniline (PAn), The redox reaction of DMcT was accelerated by PAn in acidic condition. The cell using this anodic material was set-up and characterized in aqueous electrolyte.

Tunable vacancy defect chemistry on free-standing carbon cathode for lithium-sulfur batteries

The defect chemistry is successfully modulated on free-standing and binder-free carbon cathodes for highly efficient Li-S redox reactions.Such rationally regulated defect engineering realizes the synchronization of ion/electron-conductive and defect-rich networks on the threedimension carbon cathode,leading to its tunable activity for both relieving the shuttle phenomenon and accelerating the sulfur redox reaction kinetics.As expected,the defective carbon cathode harvests a high rate capacity of 1217.8 mAh g^(-1)at 0.2 C and a superior capacity retention of61.7%at 2 C after 500 cycles.Even under the sulfur mass loading of 11.1 mg cm^(-2),the defective cathode still holds a remarkable areal capacity of 8.5 mAh cm^(-2).