Polyanionic hydrogel electrolyte enables reversible and durable Zn anode for efficient Zn-based energy storage

Aqueous Zn-ion energy storage systems,which are expected to be integrated into intelligent electronics as a secure power supply,suffer poor reversibility of Zn anodes,predominantly associated with dendritic growth and side reactions.This study introduces a polyanionic strategy to address these formidable issues by developing a hydrogel electrolyte(PACXHE)with carboxyl groups.Notably,the carboxyl groups within the hydrogel structure establish favorable channels to promote the transport of Zn^(2+)ions.They also expedite the desolvation of hydrated Zn^(2+)ions,leading to enhanced deposition kinetics.Additionally,these functional groups confine interfacial planar diffusion and promote preferential deposition along the(002)plane of Zn,enabling a smooth surface texture of the Zn anode.This multifaceted regulation successfully achieves the suppression of Zn dendrites and side reactions,thereby enhancing the electrochemical reversibility and service life during plating/stripping cycles.Therefore,such an electrolyte demonstrates a high average Coulombic efficiency of 97.7%for 500 cycles in the Zn‖Cu cell and exceptional cyclability with a duration of 480 h at 1 mA cm^(-2)/1 mA h cm^(-2)in the Zn‖Zn cell.Beyond that,the Zn-ion hybrid micro-capacitor employing PACXHE exhibits satisfactory cycling stability,energy density,and practicality for energy storage in flexible,intelligent electronics.The present polyanionic-based hydrogel strategy and the development of PACXHE represent significant advancements in the design of hydrogel electrolytes,paving the way for a more sustainable and efficient future in the energy storage field.

Vanadium-based polyanionic compounds as cathode materials for sodium-ion batteries:Toward high-energy and high-power applications

Sodium ion batteries(SIBs)have been regarded as one of the alternatives to lithium ion batteries owing to their wide availability and significantly low cost of sodium sources.However,they face serious challenges of low energy&power density and short cycling lifespan owing to the heavy mass and large radius of Na^(+).Vanadium-based polyanionic compounds have advantageous characteristic of high operating voltage,high ionic conductivity and robust structural framework,which is conducive to their high energy&power density and long lifespan for SIBs.In this review,we will overview the latest V-based polyanionic compounds,along with the respective characteristic from the intrinsic crystal structure to performance presentation and improvement for SIBs.One of the most important aspect is to discover the essential problems existed in the present V-based polyanionic compounds for high-energy&power applications,and point out most suitable solutions from the crystal structure modulation,interface tailoring and electrode configuration design.Moreover,some scientific issues of V-based polyanionic compounds shall be also proposed and related future direction shall be provided.We believe that this review can serve as a motivation for further development of novel V-based polyanionic compounds and drive them toward high energy&power applications in the near future.

Enhanced electrode kinetics and properties via anionic regulation in polyanionic Na_(3+x)V_(2)(PO_(4))_(3-x)(P_(2)O_(7))_(x) cathode material

Mixing polyanion cathode materials are promising candidates for the development of next-generation batteries, owing to their structural robustness and low-volume changes, yet low conductivity of polyanion hinders their practical capacity. Herein, the anion-site regulation is proposed to elevate the electrode kinetics and properties of polyanionic cathode. Multivalent anion P_(2)O_(7)^(4-) is selected to substitute the PO_(4)^(3-) in Na_(3)V_(2)(PO_(4))_(3) (NVP) lattice and regulate the ratio of polyanion groups to prepare Na_(3+x)V_(2)(PO_(4))_(3-x)(P_(2)O_(7))_(x)(NVPP_(x), 0 ≤ x ≤ 0.15) materials.The optimal Na_(3.1)V_(2)(PO_(4))_(2.9)(P_(2)O_(7))_(0.1) (NVPP_(0.1)) material can deliver remarkably elevated specific capacity(104 mAh g^(-1) at 0.1 C, 60 mAh g^(-1) at 20 C, respectively), which is higher than those of NVP. Moreover, NVPP_(0.1) exhibits outstanding cyclic stability(91% capacity retention after 300 cycles at 1 C). Experimental analyses reveal that the regulation of anions improves the structure stability, increases the active Na occupancy in the lattice and accelerates the Na+migration kinetics. The strategy of anion-site regulation provides the researchers a reference for the design of new high-performance polyanionic materials.

Hydrophilic polyanionic hydrogel electrolyte for anti-freezing and bending resistant zinc-ion hybrid supercapacitors

Zinc-ion hybrid supercapacitors(ZHSCs)have been widely considered as promising candidates for flexible electrochemical energy storage devices.The key challenge is to develop hydrogel electrolytes with high hydrophilicity,anti-freezing,bending resistance,and stable interface with electrodes.This study reported a hydrogel electrolyte system that can meet the above functions,in which the zincophilic and negatively charged SO3−,migratable Na+,abundant hydrophilic functional groups,gum xanthan,and porous architecture could effectively promote the electrochemical performance of ZHSCs.ZHSCs with such hydrogel electrolytes not only exhibited good low-temperature performance but also showed excellent bending resistance ability.A high specific capacitance could be kept after a long air-working lifespan over 10,000 cycles under a wide operation voltage of 1.85 V at−10℃.Furthermore,flexible ZHSCs could maintain the capacitance retention of 93.18%even after continuous 500 bends at an angle of 180°.The designed hydrogel electrolytes could be also used for other electrochemical energy storage devices with anti-freezing and bending resistance by changing electrolyte salt.

Recent Progress in Polyanionic Anode Materials for Li(Na)‑Ion Batteries

In recent years,rechargeable lithium-ion batteries(LIBs)have become widely used in everyday applications such as portable electronic devices,electric vehicles and energy storage systems.Despite this,the electrochemical performance of LIBs cannot meet the energy demands of rapidly growing technological evolutions.And although significant progress has been made in the development of corresponding anodes based primarily on carbon,oxide and silicon materials,these materials still possess shortcomings in current LIB applications.For example,graphite exhibits safety concerns due to an operating potential close to that of lithium(Li)metal plating whereas Li4Ti5O12 possesses low energy density for high operation potential and silicon experiences limited cyclability for large volume expansion during charging/discharging.Alternatively,polyanionic compounds such as(PO_(4))^(3–),(SiO_(4))^(4–),(SO_(4))^(2–)and(BO_(3))^(3−)as electrode materials have gained increasing attention in recent years due to their ability to stabilize structures,adjust redox couples and provide migration channels for"guest"ions,resulting in corresponding electrode materials with long-term cycling,high energy density and outstanding rate capability.Based on these advantages and combined with recent findings in terms of silicate anodes,this review will summarize the recent progress in the development of polyanion-based anode materials for LIBs and sodium-ion batteries.Furthermore,this review will present our latest research based on polyanion groups such as(GeO_(4))^(4–)to compensate for the lack of available studies and to provide our perspective on these materials.

Insoluble polyanionic anthraquinones with two strong ionic O–K bonds as stable organic cathodes for pure organic K-ion batteries

A new organic cathode namely potassium 2,6-dihydroxyanthraquinone(AQ26OK,theoretical capacity(CT)=169 mA h g^(-1))is synthesized and fully characterized for Kion batteries.AQ26OK is called polyanionic organic cathode because it has a polyanionic organic skeleton(-2 valent)and two strong ionic K-O bonds.Consequently,the polyanionic AQ26OK is hardly soluble into most organic liquid electrolytes.In half cells(0.3-3.4 V vs.K^(+)/K)using 1 mol L^(-1) KPF6 in dimethoxyethane,AQ26OK delivers a highly stable specific capacity of 201 mA h g^(-1)@50 mA g^(-1) over 450 cycles(4-month test)and realizes~106 mA h g^(-1) for 3200 cycles at 500 mA g^(-1).Using the reduced state(K4TP)of potassium terephthalate(K2TP)as the organic anode,the resulting K4TP Ⅱ AQ26OK organic potassium-ion batteries can display a highly stable average discharge capacity of 135 mA h g^(-1) cathodeover 250 cycles at 100 mA g^(-1) and~47 mA h g^(-1) for 1000 cycles at 500 mA g^(-1) during the working voltage of 0.01-3.1 V.To the best of our knowledge,AQ26OK is among the best stable cathodes reported for K-ion batteries.

Highly Ordered Thermoplastic Polyurethane/Aramid Nanofiber Conductive Foams Modulated by Kevlar Polyanion for Piezoresistive Sensing and Electromagnetic Interference Shielding

Highly ordered and uniformly porous structure of conductive foams is a vital issue for various functional purposes such as piezoresistive sensing and electromagnetic interference(EMI) shielding. With the aids of Kevlar polyanionic chains, thermoplastic polyurethane(TPU) foams reinforced by aramid nanofibers(ANF) with adjustable pore-size distribution were successfully obtained via a nonsolvent-induced phase separation. In this regard, the most outstanding result is the in situ formation of ANF in TPU foams after protonation of Kevlar polyanion during the NIPS process. Furthermore, in situ growth of copper nanoparticles(Cu NPs) on TPU/ANF foams was performed according to the electroless deposition by using the tiny amount of pre-blended Ti_(3)C_(2)T_(x) MXene as reducing agents. Particularly, the existence of Cu NPs layers significantly promoted the storage modulus in 2,932% increments, and the well-designed TPU/ANF/Ti_(3)C_(2)T_(x) MXene(PAM-Cu) composite foams showed distinguished compressive cycle stability. Taking virtues of the highly ordered and elastic porous architectures, the PAM-Cu foams were utilized as piezoresistive sensor exhibiting board compressive interval of 0–344.5 kPa(50% strain) with good sensitivity at 0.46 kPa^(-1). Meanwhile,the PAM-Cu foams displayed remarkable EMI shielding effectiveness at 79.09 dB in X band. This work provides an ideal strategy to fabricate highly ordered TPU foams with outstanding elastic recovery and excellent EMI shielding performance, which can be used as a promising candidate in integration of satisfactory piezoresistive sensor and EMI shielding applications for human–machine interfaces.

Mixed polyanion cathode materials:Toward stable and high-energy sodium-ion batteries

Sodium-ion batteries(SIBs)are considered as one of the most fascinating alternatives to lithium-ion batteries for grid-scale energy storage applications because of the low cost and wide abundance of sodium resources.Among various cathode materials,mixed polyanion compounds come into the spotlight as promising electrode materials due to their superior electrochemical properties,such as high working voltage,long cycling stability,and facile reaction kinetics.In this review,we summarize the recent development in the exploration of different mixed polyanion cathode materials for SIBs.We provide a comprehensive understanding of the structure-composition-performance relationship of mixed polyanion cathode materials together with the discussion of their sodium storage mechanisms.It is anticipated that further innovative works on the material design of advanced cathode materials for batteries can be inspired.

Boosting the Electrochemical Performance of Li-and Mn-Rich Cathodes by a Three-in-One Strategy

There are plenty of issues need to be solved before the practi-cal application of Li-and Mn-rich cathodes,including the detrimental voltage decay and mediocre rate capability,etc.Element doping can e ectively solve the above problems,but cause the loss of capacity.The introduction of appropriate defects can compensate the capacity loss;however,it will lead to structural mismatch and stress accumulation.Herein,a three-in-one method that combines cation–polyanion co-doping,defect construction,and stress engineering is pro-posed.The co-doped Na^(+)/SO_(4)^(2-)can stabilize the layer framework and enhance the capacity and voltage stability.The induced defects would activate more reac-tion sites and promote the electrochemical performance.Meanwhile,the unique alternately distributed defect bands and crystal bands structure can alleviate the stress accumulation caused by changes of cell parameters upon cycling.Consequently,the modified sample retains a capacity of 273 mAh g^(-1)with a high-capacity retention of 94.1%after 100 cycles at 0.2 C,and 152 mAh g^(-1)after 1000 cycles at 2 C,the corresponding voltage attenuation is less than 0.907 mV per cycle.

Hydrothermal Synthesis and Structure of[{Mo_8V_4O_(36)(VO_4)(VO)_2}n]^(7n-)Bi-capped α-Keggin Fragments Linked to a Chain

The title compound, (H2en)3H3O{Mo8V4O36(VO4) (VO)2} ?4H2O, was hydrothermally synthesized and structurally characterized by means of IR, ESR spectrum and single crystal X-ray diffraction. It crystallized in a monoclinic system with space group P21/c, a=1. 980 4(4) nm, 6=2. 063 4(4) nm, c=l. 192 0(2) nm, =94. 76(3)?and deep black colour. The compound contains V-centered bi-capped a-Keggin fragments {Mo8V7O42} that are linked together by edge-shared units V O5 via V桹梀 bonds, forming a chain.

An advanced low-cost cathode composed of graphene-coated Na_(2.4)Fe_(1.8)(SO_(4))_(3) nanograins in a 3D graphene network for ultra-stable sodium storage

Iron-based electrodes have attracted great attention for sodium storage because of the distinct cost effectiveness.However,exploring suitable iron-based electrodes with high power density and long duration remains a big challenge.Herein,a spray-drying strategy is adopted to construct graphene-coated Na_(2.4)Fe_(1.8)(SO_(4))_(3) nanograins in a 3D graphene microsphere network.The unique structural and compositional advantages endow these electrodes to exhibit outstanding electrochemical properties with remarkable rate performance and long cycle life.Mechanism analyses further explain the outstanding electrochemical properties from the structural aspect.

Structural Characters and Isolated Stability of Phosphorus Polyanions

The optimized geometries at the RHF/6-311++G** level, the relatively stable energy at the MPW1PW91/6-311++G** level and the structural characters of anions have been acquired, indicating the stability is related to the chemical bonding of μ2?P atoms and the distri- bution of negative charges. The configurations of cage units P8 4- and P9 5- are stable due to the less torsion, but their ES values are relatively higher than that of P7 3- with more μ2?P atoms and the isolated stability is lower than that of P7 . They potentially play an important role as intermediate 3- in chemical reaction of producing complicated polyphosphides. Based on the related electronic properties, a stable polyanion must have low valence electron concentration, no (μ2?P)?(μ2?P) bond and a little dispersive charge. The earmark IR frequencies of cage units have been assigned to the vibration models in the end.

Spectroscopic Sensing Characteristics of Novel Osmium Carbonyl Complexes to DNA and Other Polyanions

In this research, the absorbance and luminescence response of two osmium(II) phenathrane (phen) carbonyl complexes to various DNA, heparin and i-carrageenan polyanions were studied. The [Os(phen)2CO(L)]2+ complexes with L either a 4-phenyl pyridine (4-phpy) or phenyl imidazole (phimd) group exhibit moderate luminescent intensity in the visible region, their intensities are highly altered by the addition of DNA and other polyanion samples. These luminescent responses to polyanions were also compared with the [Ru(phen)3]2+ complex. In ethanol solution, the presence of polyanions significantly enhanced the luminescent emission intensity of [Os(phen)2CO(L)]2+ complexes with a blue shift. While the polyanions all showed emission enhancement on the highly lumi-nescent [Ru(phen)3]2+ complex in ethanol solution with a red spectra shift. The [Os(phen)2CO(L)] 2+ with (phimd) ligand has the lowest emission in ethanol solution, its intensity can be enhanced up to 11 times in the presence of DNA polyanions. This enhancement for all the complexes in ethanol is mainly due to their electrostatic interaction with the anion sites and with some degree of ligand intercalation into the polyanion hydrophobic structure which reduced the solvent quenching of the complexes. The blue shift of the (4-phpy) and particularly (phimd) Os(II)CO complexes indicate an insertion of the (4-phpy) or (phimd) group into the polymer chains. The two new Os(II)CO complexes has great potential to be used as luminescence sensors for DNA and polyanion detection in the low micro molar range with high sensitivity.

Reinforced concrete-like Na_(3.5)V_(1.5)Mn_(0.5)(PO_(4))_(3)@graphene hybrids with hierarchical porosity as durable and high-rate sodium-ion battery cathode

Realizing high-rate capability and high-efficiency utilization of polyanionic cathode materials is of great importance for practical sodium-ion batteries(SIBs) since they usually suffer from extremely low electronic conductivity and limited ionic diffusion kinetics. Herein, taking Na_(3.5)V_(1.5)Mn_(0.5)(PO_(4))_(3)(NVMP) as an example, a reinforced concrete-like hierarchical and porous hybrid(NVMP@C@3DPG) built from 3D graphene(“rebar”) frameworks and in situ generated carbon coated NVMP(“concrete”) has been developed by a facile polymer assisted self-assembly and subsequent solid-state method. Such hybrids deliver superior rate capability(73.9 m Ah/g up to 20 C) and excellent cycling stability in a wide temperature range with a high specific capacity of 88.4 m Ah/g after 5000 cycles at 15 C at room temperature, and a high capacity retention of 97.1% after 500 cycles at 1 C(-20 ℃), and maintaining a high reversible capacity of 110.3 m Ah/g in full cell. This work offers a facile and efficient strategy to develop advanced polyanionic cathodes with high-efficiency utilization and 3D electron/ion transport systems.

Extracellular Disintegration of Viral Proteins as an Innovative Strategy for Developing Broad-Spectrum Antivirals Against Coronavirus

The coronavirus disease 2019(COVID-19)pandemic,caused by severe acute respiratory syndrome coronavirus 2(SARS-CoV-2),has claimedmillions of lives and caused innumerable economic losses worldwide.Unfortunately,state-of-the-art treatments still lag behind the continual emergence of new variants.Key to resolving this issue is developing antivirals to deactivate coronaviruses regardless of their structural evolution.Here,we report an innovative antiviral strategy involving extracellular disintegration of viral proteins with hyperanion-grafted enediyne(EDY)molecules.The core EDY generates reactive radical species and causes significant damage to the spike protein of coronavirus,while the hyperanion groups ensure negligible cytotoxicity of the molecules.The EDYs exhibit antiviral activity down to nanomolar concentrations,and the selectivity index of up to 20,000 against four kinds of human coronavirus,including the SARS-CoV-2 Omicron variant,suggesting the high potential of this new strategy in combating the COVID-19 pandemic and a future“disease X.”

A novel low-cost and environment-friendly cathode with large channels and high structure stability for potassium-ion storage

Potassium-ion batteries (KIBs) are promising candidates for large-scale energy storage due to the abundance of potassium and its chemical similarity to lithium.Nevertheless,the performances of KIBs are still unsatisfactory for practical applications,mainly hindered by the lack of suitable cathode materials.Herein,combining the strong inductive effect of sulphate and the feasible preparation of Fe^(2+)-containing compounds in oxalate system,a compound with novel architecture,K_(4)Fe_(3)(C_(2)O_(4))_(3)(SO_(4))_(2),has been identified as a lowcost and environmentally friendly cathode for stable potassium-ion storage.Its unique crystal structure possesses an unprecedented two-dimensional framework of triple layers,with 3.379Åinterlayer distance and large intralayer rings in the size of 4.576×6.846Å.According to first-principles simulations,such a configuration is favorable for reversible K-ion migration with a very low volume change of 6.4%.Synchrotron X-ray absorption spectra and X-ray diffraction characterizations at different charging/discharging states and electrochemical performances based on its half and full cells further verify its excellent reversibility and structural stability.Although its performance needs to be improved via further composition tuning with multi-valent transition metals,doping,structural optimization,etc.,this study clearly presents a stable structural model for K-ion cathodes with merits of low cost and environmental friendliness.

Raising the capacity of lithium vanadium phosphate via anion and cation co-substitution

The pursuit for batteries with high specific energy provokes the research of high-voltage/capacity cathode materials with superior stability and safety as the alternative for lithium iron phosphate.Herein,using the sol-gel method,a lithium vanadium phosphate with higher average discharge voltage(3.8 V,vs.Li+/Li) was obtained from a single source for Mg2+ and Cl-co-substitution and uniform carbon coating,and a nearly theoretical capacity(130.1 mA h g^-1) and outstanding rate performance(25 C) are acquired together with splendid capacity retention(80%) after 650 cycles.This work reveals that the well-sized anion and cation substitution and uniform carbon coating are of both importance to accelerate kinetic performance in the context of nearly undisturbed crystal structure for other analogue materials.It is anticipated that the electrochemistry comprehension will shed light on preparing cathode materials with high energy density in the future.

Reorganizing electronic structure of Li3V2(PO4)3 using polyanion(BO3)^3-:towards better electrochemical performances

Doping modification of electrode materials is a sought-after strategy to improve their electrochemical performance in the secondary batteries field. Herein,polyanion（BO3）^3-doped Li3V2（PO4）3 cathode materials were successfully synthesized via a wet coordination method. The effects of（BO3）^3- doping content on crystal structure, morphology and electrochemical performance were explored by X-ray diffraction（XRD）, scanning electron microscopy（SEM）, cyclic voltammetry（CV） and electrochemical impedance spectroscopy（EIS）. All the asprepared samples have the same monoclinic structure;among them, Li3V2（PO4）（2.75）（BO3）（0.15） sample has relatively uniform and optimized particle size. In addition, this sample has the highest discharge capacity and the best cycling stability, with an initial discharge capacity of 120.4mAh·g^-1, and after 30 cycles at a rate of 0.1C, the discharge capacity still remains 119.3 mAh·g^-1. It is confirmed that moderate polyanion（BO3）^3- doping can rearrange the electronic structure of the bulk Li3V2（PO4）3,lower the charge transfer resistance and further improve the electrochemical behaviors.

Amorphous NaVOPO_(4)as a High-Rate and Ultrastable Cathode Material for Sodium-Ion Batteries

The low cost and profusion of sodium resources make sodium-ion batteries(SIBs)a potential alternative to lithium-ion batteries for grid-scale energy storage applications.However,the use of conventional cathode materials for Na-ion intercalation/deintercalation cannot satisfy the requirements of high-powered and long lifespan performance due to multiphase transition and lattice confinement.

Synthesis method and crystal structure of novel mixed valence Mo~Ⅴ-Mo~Ⅵ polymetallate cluster Na_3H_3[H_8Mo_(57)Fe_6~ⅡO_(185)(NO)_6(H_2O)_(16)(MoO)_2]·81H_2O

Understanding the driving force for the formation of high-nuclearity clusters is still aformidable challenge. Recently, we have reported two crystal structures with the largestpolymetallate clusters involving mixed-valence molybdenum and vanadium （Ⅳ） or Fe （Ⅲ）, ofwhich the Mo; V and Mo; Fe ratios are 57:6. Here we report the crystal structure ofnew heteropolyanion involving mixed-valence molybdenum and Fe（Ⅱ）. [H8Mo57Fe6ⅡO185（NO）6·（H2O）16（MoO）2]6-,of which the Mo:Fe ratio is as high as 59:6.