Synergistic coupling among Mg_(2)B_(2)O_(5),polycarbonate and N,Ndimethylformamide enhances the electrochemical performance of PVDF-HFP-based solid electrolyte

Polymer solid electrolytes(SPEs)based on the[solvate-Li+]complex structure have promising prospects in lithium metal batteries(LMBs)due to their unique ion transport mechanism.However,the solvation structure may compromise the mechanical performance and safety,hindering practical application of SPEs.In this work,a composite solid electrolyte(CSE)is designed through the organic-inorganic syner-gistic interaction among N,N-dimethylformamide(DMF),polycarbonate(PC),and Mg_(2)B_(2)O_(5) in poly(vinylidene fluoride-co-hexafluoropropylene)(PVDF-HFP).Flame-retardant Mg_(2)B_(2)O_(5) nanowires provide non-flammability to the prepared CSEs,and the addition of PC improves the dispersion of Mg_(2)B_(2)O_(5) nanowires.Simultaneously,the organic-inorganic synergistic action of PC plasticizer and Mg_(2)B_(2)O_(5) nanowires pro-motes the dissociation degree of LiTFSI and reduces the crystallinity of PVDF-HFP,enabling rapid Li ion transport.Additionally,Raman spectroscopy and DFT calculations confirm the coordination between Mg atoms in Mg_(2)B_(2)O_(5) and N atoms in DMF,which exhibits Lewis base-like behavior attacking adjacent C-F and C-H bonds in PVDF-HFP while inducing dehydrofluorination of PVDF-HFP.Based on the syner-gistic coupling of Mg_(2)B_(2)O_(5),PC,and DMF in the PVDF-HFP matrix,the prepared CSE exhibits superior ion conductivity(9.78×10^(-4) s cm^(-1)).The assembled Li symmetric cells cycle stably for 3900 h at a current density of 0.1 mA cm^(-2) without short circuit.The LFP||Li cells assembled with PDL-Mg_(2)B_(2)O_(5)/PC CSEs show excellent rate capability and cycling performance,with a capacity retention of 83.3%after 1000 cycles at 0.5 C.This work provides a novel approach for the practical application of organic-inorganic Synergistic CSEs in LMBs.

Photo-rechargeable batteries and supercapacitors:Critical roles of carbon-based functional materials

As a clean and renewable energy source,solar energy is a competitive alternative to replace conventional fossil fuels.Nevertheless,its serious fluctuating nature usually leads to a poor alignment with the actual energy demand.To solve this problem,the direct solar-to-electrochemical energy conversion and storage have been regarded as a feasible strategy.In this context,the development of high-performance integrated devices based on solar energy conversion parts(i.e.,solar cells or photoelectrodes)and electrochemical energy storage units(i.e.,rechargeable batteries or supercapacitors[SCs])has become increasingly necessary and urgent,in which carbon and carbon-based functional materials play a fundamental role in determining their energy conversion/storage performances.Herein,we summarize the latest progress on these integrated devices for solar electricity energy conversion and storage,with special emphasis on the critical role of carbon-based functional materials.First,principles of integrated devices are introduced,especially roles of carbon-based materials in these hybrid energy devices.Then,two major types of important integrated devices,including photovoltaic and photoelectrochemicalrechargeable batteries or SCs,are discussed in detail.Finally,key challenges and opportunities in the future development are also discussed.By this review,we hope to pave an avenue toward the development of stable and efficient devices for solar energy conversion and storage.

Recent Progress of Conductive Metal-Organic Frameworks for Electrochemical Energy Storage

The development of reliable and low-cost energy storage systems is of considerable value in using renewable and clean energy sources,and exploring advanced electrodes with high reversible capacity,excellent rate performance,and long cycling life for Li/Na/Zn-ion batteries and supercapacitors is the key problem.Particularly because of their diverse structure,high specific surface area,and adjustable redox activity,electrically conductive metal-organic frameworks(c-MOFs)are considered promising candidates for these electrochemical applications,and a detailed overview of the recent progress of c-MOFs for electrochemical energy storage and their intrinsic energy storage mechanism helps realize a comprehensive and systematic understanding of this progress and further achieve highly efficient energy storage and conversion.Herein,the chemical structure of c-MOFs and their conductive mechanism are first introduced.Subsequently,a comprehensive summarization of the current applications of c-MOFs in energy storage systems,namely supercapacitors,LIBs,SIBs,and ZIBs,is presented.Finally,the prospects and challenges of c-MOFs toward much higher-performance energy storage devices are presented,which should illuminate the future scientific research and practical applications of c-MOFs in energy storage fields.

Lithium-Ion Charged Polymer Channels Flattening Lithium Metal Anode

The concentration difference in the near-surface region of lithium metal is the main cause of lithium dendrite growth.Resolving this issue will be key to achieving high-performance lithium metal batteries(LMBs).Herein,we construct a lithium nitrate(LiNO_(3))-implanted electroactiveβphase polyvinylidene fluoride-co-hexafluoropropylene(PVDF-HFP)crystalline polymorph layer(PHL).The electronegatively charged polymer chains attain lithium ions on the surface to form lithium-ion charged channels.These channels act as reservoirs to sustainably release Li ions to recompense the ionic flux of electrolytes,decreasing the growth of lithium dendrites.The stretched molecular channels can also accelerate the transport of Li ions.The combined effects enable a high Coulombic efficiency of 97.0%for 250 cycles in lithium(Li)||copper(Cu)cell and a stable symmetric plating/stripping behavior over 2000 h at 3 mA cm^(-2)with ultrahigh Li utilization of 50%.Furthermore,the full cell coupled with PHL-Cu@Li anode and Li Fe PO_(4) cathode exhibits long-term cycle stability with high-capacity retention of 95.9%after 900 cycles.Impressively,the full cell paired with LiNi_(0.87)Co_(0.1)Mn_(0.03)O_(2)maintains a discharge capacity of 170.0 mAh g^(-1)with a capacity retention of 84.3%after 100 cycles even under harsh condition of ultralow N/P ratio of 0.83.This facile strategy will widen the potential application of LiNO_(3)in ester-based electrolyte for practical high-voltage LMBs.

Recent advances in chemical adsorption and catalytic conversion materials for Li–S batteries

Owing to their low cost,high energy densities,and superior performance compared with that of Li-ion batteries,Li–S batteries have been recognized as very promising next-generation batteries.However,the commercialization of Li–S batteries has been hindered by the insulation of sulfur,significant volume expansion,shuttling of dissolved lithium polysulfides(Li PSs),and more importantly,sluggish conversion of polysulfide intermediates.To overcome these problems,a state-of-the-art strategy is to use sulfur host materials that feature chemical adsorption and electrocatalytic capabilities for Li PS species.In this review,we comprehensively illustrate the latest progress on the rational design and controllable fabrication of materials with chemical adsorbing and binding capabilities for Li PSs and electrocatalytic activities that allow them to accelerate the conversion of Li PSs for Li–S batteries.Moreover,the current essential challenges encountered when designing these materials are summarized,and possible solutions are proposed.We hope that this review could provide some strategies and theoretical guidance for developing novel chemical anchoring and electrocatalytic materials for high-performance Li–S batteries.

Bio-Derived Hierarchical Multicore–Shell Fe2N-Nanoparticle-Impregnated N-Doped Carbon Nanofiber Bundles:A Host Material for Lithium-/Potassium-Ion Storage

Despite the significant progress in the fabrication of advanced electrode materials,complex control strategies and tedious processing are often involved for most targeted materials to tailor their compositions,morphologies,and chemistries.Inspired by the unique geometric structures of natural biomacromolecules together with their high affinities for metal species,we propose the use of skin collagen fibers for the template crafting of a novel multicore-shell Fe2N-carbon framework anode configuration,composed of hierarchical N-doped carbon nanofiber bundles firmly embedded with Fe2N nanoparticles(Fe2N@N-CFBs).In the resultant heterostructure,the Fe2N nanoparticles firmly confined inside the carbon shells are spatially isolated but electronically well connected by the long-range carbon nanofiber framework.This not only provides direct and continuous conductive pathways to facilitate electron/ion transport,but also helps cushion the volume expansion of the encapsulated Fe2N to preserve the electrode microstructure.Considering its unique structural characteristics,Fe2N@N-CFBs as an advanced anode material exhibits remarkable electrochemical performances for lithium-and potassium-ion batteries.Moreover,this bio-derived structural strategy can pave the way for novel low-cost and high-efficiency syntheses of metal-nitride/carbon nanofiber heterostructures for potential applications in energy-related fields and beyond.

Recent progress on the recycling technology of Li-ion batteries

Lithium-ion batteries(LIBs)have been widely applied in portable electronic devices and electric vehicles.With the booming of the respective markets,a huge quantity of spent LIBs that typically use either LiFePO_(4) or Li N_(x)Co_(y)Mn_(z)O_(2) cathode materials will be produced in the very near future,imposing significant pressure for the development of suitable disposal/recycling technologies,in terms of both environmental protection and resource reclaiming.In this review,we firstly do a comprehensive summary of the-state-of-art technologies to recycle Li N_(x)Co_(y)Mn_(z)O_(2) and LiFePO_(4)-based LIBs,in the aspects of pretreatment,hydrometallurgical recycling,and direct regeneration of the cathode materials.This closed-loop strategy for cycling cathode materials has been regarded as an ideal approach considering its economic benefit and environmental friendliness.Afterward,as for the exhausted anode materials,we focus on the utilization of exhausted anode materials to obtain other functional materials,such as graphene.Finally,the existing challenges in recycling the LiFePO_(4) and Li N_(x)Co_(y)Mn_(z)O_(2) cathodes and graphite anodes for industrial-scale application are discussed in detail;and the possible strategies for these issues are proposed.We expect this review can provide a roadmap towards better technologies for recycling LIBs,shed light on the future development of novel battery recycling technologies to promote the environmental benignity and economic viability of the battery industry and pave way for the large-scale application of LIBs in industrial fields in the near future.

Graphitic carbon nitride (g-C3N4)-based nanosized heteroarrays: Promising materials for photoelectrochemical water splitting

Photoelectrochemical(PEC)water splitting is recognized as a sustainable strategy for hydrogen generation due to its abundant hydrogen source,utilization of inexhaustible solar energy,high-purity product,and environment-friendly process.To actualize a practical PEC water splitting,it is paramount to develop efficient,stable,safe,and low-cost photoelectrode materials.Recently,graphitic carbon nitride(g-C3N4)has aroused a great interest in the new generation photoelectrode materials because of its unique features,such as suitable band structure for water splitting,a certain range of visible light absorption,nontoxicity,and good stability.Some inherent defects of g-C3N4,however,seriously impair further improvement on PEC performance,including low electronic conductivity,high recombination rate of photogenerated charges,and limited visible light absorption at long wavelength range.Construction of g-C3N4-based nanosized heteroarrays as photoelectrodes has been regarded as a promising strategy to circumvent these inherent limitations and achieve the high-performance PEC water splitting due to the accelerated exciton separation and the reduced combination of photogenerated electrons/holes.Herein,we summarize in detail the latest progress of g-C3N4-based nanosized heteroarrays in PEC water-splitting photoelectrodes.Firstly,the unique advantages of this type of photoelectrodes,including the highly ordered nanoarray architectures and the heterojunctions,are highlighted.Then,different g-C3N4-based nanosized heteroarrays are comprehensively discussed,in terms of their fabrication methods,PEC capacities,and mechanisms,etc.To conclude,the key challenges and possible solutions for future development on g-C3N4-based nanosized heteroarray photoelectrodes are discussed.

Effect of Starch Addition on Properties of Corundum-mullite Porous Ceramics

Corundum-mullite porous ceramics(CMPCs)were fabricated using fly ash and aluminum ash as the raw materials,adding different amounts of starch(0,10%,20%,and 30%,by mass)as the pore-forming agent,molding and firing at 1200℃ for 1 h.The apparent porosity,the bulk density,the cold compressive strength,the thermal shock resistance and the thermal conductivity of the CMPCs were tested.The phase composition and the microstructure of the CMPCs were characterized by XRD and SEM.The effect of the starch addition on the properties of the CMPCs was studied.The results show that:(1)the CMPCs with high porosity can be successfully prepared by adding starch as the pore-forming agent and firing at 1200℃ for 1 h;(2)with the starch addition increasing,the porosity increases;the cold compressive strength and the number of the quenching cycles of the CMPCs decrease,but they remain at high levels;meanwhile,the thermal conductivity decreases;(3)generally,when adding 20 mass%starch,the CMPC has the apparent porosity of 48.6%,the cold compressive strength of 52.1 MPa,the quenching cycles of 5 and the thermal conductivity of 1.63 W·m-1·K-1 and 1.52 W·m-1·K-1,respectively,at 25℃ and 500℃,showing good performance.

Intrinsic electrochemical activity of Ni in Ni_(3)Sn_(4) anode accommodating high capacity and mechanical stability for fast-charging lithium-ion batteries

Fast interfacial kinetics derived from bicontinuous three-dimensional(3D)architecture is a strategic feature for achieving fast-charging lithium-ion batteries(LIBs).One of the main reasons is its large active surface and short diffusion path.Yet,understanding of unusual electrochemical properties still remain great challenge due to its complexity.In this study,we proposed a nickel–tin compound(Ni_(3)Sn_(4))supported by 3D Nickel scaffolds as main frame because the Ni_(3)Sn_(4) clearly offers a higher reversible capacity and stable cycling performance than bare tin(Sn).In order to verify the role of Ni,atomic-scale simulation based on density functional theory systematically addressed to the reaction mechanism and structural evolution of Ni_(3)Sn_(4) during the lithiation process.Our findings are that Ni enables Ni_(3)Sn_(4) to possess higher mechanical stability in terms of reactive flow stress,subsequently lead to improve Li storage capability.This study elucidates an understanding of the lithiation mechanism of Ni_(3)Sn_(4) and provides a new perspective for the design of high-capacity and high-power 3D anodes for fast-charging LIBs.

Bifunctional flame retardant solid-state electrolyte toward safe Li metal batteries

Solid polymer electrolytes(SPEs)are one of the most promising alternatives to flammable liquid electrolytes for building safe Li metal batteries.Nevertheless,the poor ionic conductivity at room temperature(RT)and low resistance to Li dendrites seriously hinder the commercialization of SPEs.Herein,we design a bifunctional flame retardant SPE by combining hydroxyapatite(HAP)nanomaterials with Nmethyl pyrrolidone(NMP)in the PVDF-HFP matrix.The addition of HAP generates a hydrogen bond network with the PVDF-HFP matrix and cooperates with NMP to facilitate the dissociation of Li TFSI in the PVDF-HFP matrix.Consequently,the prepared SPE demonstrates superior ionic conductivity at RT,excellent fireproof properties,and strong resistance to Li dendrites.The assembled Li symmetric cell with prepared SPE exhibits a stable cycling performance of over 1200 h at 0.2 m A cm^(-2),and the solid-state LiFePO_4||Li cell shows excellent capacity retention of 85.3%over 600 cycles at 0.5 C.

Long-lasting,reinforced electrical networking in a high-loading Li_(2)S cathode for high-performance lithium–sulfur batteries

Realizing a lithium sulfide(Li_(2)S)cathode with both high energy density and a long lifespan requires an innovative cathode design that maximizes electrochemical performance and resists electrode deterioration.Herein,a high-loading Li_(2)S-based cathode with micrometric Li_(2)S particles composed of two-dimensional graphene(Gr)and one-dimensional carbon nanotubes(CNTs)in a compact geometry is developed,and the role of CNTs in stable cycling of high-capacity Li–S batteries is emphasized.In a dimensionally combined carbon matrix,CNTs embedded within the Gr sheets create robust and sustainable electron diffusion pathways while suppressing the passivation of the active carbon surface.As a unique point,during the first charging process,the proposed cathode is fully activated through the direct conversion of Li_(2)S into S_(8) without inducing lithium polysulfide formation.The direct conversion of Li_(2)S into S_(8) in the composite cathode is ubiquitously investigated using the combined study of in situ Raman spectroscopy,in situ optical microscopy,and cryogenic transmission electron microscopy.The composite cathode demonstrates unprecedented electrochemical properties even with a high Li_(2)S loading of 10 mg cm^(–2);in particular,the practical and safe Li–S full cell coupled with a graphite anode shows ultra-long-term cycling stability over 800 cycles.

Interface challenges and optimization strategies for aqueous zinc-ion batteries

Aqueous zinc-ion batteries have advantages over lithium-ion batteries,such as low cost,and good safety.However,their development is currently facing several challenges.One of the main critical challenges is their poor electrode–electrolyte interface.Addressing this requires understanding the physics and chemistry at the electrode–electrolyte interface,including the cathode-electrolyte interface and anodeelectrolyte interface.This review first identifies and analyses the interfacial challenges of aqueous zincion batteries.Then,it discusses the design strategies for addressing the defined interfacial issues from the perspectives of electrolyte optimization,electrode modification,and separator improvement.Finally,it provides corrective recommendations and strategies for the rational design of electrode–electrolyte interface in aqueous zinc-ion batteries towards their high-performance and reliable energy storage.

Multiscale cellulose-based fireproof and thermal insulation gel materials with water-regulated forms

Different forms of construction materials(e.g.,paints,foams,and boards)dramatically improve the quality of life.With the increasing environmental requirements for buildings,it is necessary to develop a comprehensive sustainable construction material that is flexible in application and exhibits excellent performance,such as fireproofing and thermal insulation.Herein,an adjustable multiform material strategy by water regulation is proposed to meet the needs of comprehensive applications and reduce environmental costs.Multiform gels are constructed based on multiscale cellulose fibers and hollow glass microspheres,with fireproofing and thermal insulation.Unlike traditional materials,this multiscale cellulose-based gel can change forms from dispersion to paste to dough by adjusting its water content,which can realize various construction forms,including paints,foams,and low-density boards according to different scenarios and corresponding needs.

柔性锂硫电池的材料设计与实现

随着具有变形功能的移动电子设备的出现和发展,具有更高能量密度的柔性锂硫电池受到越来越多的重视。本文总结了柔性锂硫电池关键材料的发展现状,并对柔性锂硫电池的未来发展方向进行了展望。锂硫电池柔性化的主要难点在于其关键材料的变形设计,通过将硫正极附着于碳纳米管和石墨烯薄膜、聚合物等柔性基底上,利用基底提供变形支撑,能够制备出一体化的复合锂硫电池正极。相对于可变形正极材料,锂金属负极的柔性化具有更大的挑战。未来通过发展新型的锂金属担载材料或采用非金属锂负极,有望实现锂硫电池负极的可变形特征。虽然存在尚待解决的问题很多,柔性锂硫电池经过适当的电化学性能和力学性能改进,将在移动电子领域得到广泛应用。

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.

A bifunctional ethylene-vinyl acetate copolymer protective layer for dendrites-free lithium metal anodes

Lithium metal batteries are strongly considered as one of the most promising candidates for nextgeneration high-performance battery systems.However,the uncontrollable growth of lithium dendrites and the highly reactive lithium metal result in the severe safety risks and the short lifespan for highenergy-density rechargeable batteries.Here,we demonstrate a hydrophobic and ionically conductive ethylene-vinyl acetate(EVA)copolymer layer can not only endow lithium metal anodes with an air-stable and anti-water surface,but also efficiently suppress the lithium-dendrites growth during the electrochemical cycling process.Therefore,the introduction of the EVA copolymer as a bifunctional protection layer simultaneously improves the anti-water/air performance and electrochemical cycling stability of lithium metal anode.

A flexible carbon nanotube@V_(2)O_(5) film as a high-capacity and durable cathode for zinc ion batteries

Aqueous zinc-ion batteries(ZIBs)are receiving a continuously increasing attention for mobile devices,especially for the flexible and wearable electronics,due to their non-toxicity,non-flammability,and low-cost features.Despite the significant progress in achieving higher capacities for electrode materials of ZIBs,to endow them with high flexibility and economic feasibility is,however,still a significant challenge remaining unsolved.Herein,we present a highly flexible composite film composed of carbon nanotube film and V_(2)O_(5)(CNTF@V_(2)O_(5))with high strength and high conductivity,which is prepared by simply impregnating a porous CNT film with an aqueous V_(2)O_(5)sol under vacuum.For this material,intimate incorporation between V_(2)O_(5)and CNTs has been achieved,successfully integrating the high zinc ion storage capability with high mechanical flexibility.As a result,this CNTF@V_(2)O_(5)film delivers a high capacity of 356.6 m Ah g^(-1)at 0.4 A g^(-1)and excellent cycling stability with 80.1%capacity retention after 500 cycles at 2.0 A g^(-1).The novel strategy and the outstanding battery performance presented in this work should shed light on the development of high-performance and flexible ZIBs.

Metal porphyrin intercalated reduced graphene oxide nanocomposite utilized for electrocatalytic oxygen reduction

In this paper, we report a simple and facile self-assembly method to successfully fabricate cationic metal porphyrin-MtTMPyP(Mt= Cobalt(Ⅱ), Manganese(Ⅲ), or Iron(Ⅲ); TMPyP = 5, 10, 15, 20-tetrakis(N-methylpyridinium-4-yl) porphyrin) intercalated into the layer of graphene oxide(GO) by the cooperative effects of electrostatic and π-π stacking interaction between positively charged metal porphyrin and negatively charged GO sheets. Followed by reduction with hydrazine vapor, a series of novel 2 D MtTMPyP/rGO_n were fabricated. The as-prepared 2 D hybrids were fully characterized and tested as non-noble metal catalysts for oxygen reduction reaction(ORR) in an alkaline medium. The MtTMPyP/rGO_n hybrids, especially CoTMPyP/rGO_5, demonstrated an improved electrocatalytic activity for ORR and a number of exchanged electrons close to 4-electron reaction, increased stability and excellent tolerance to methanol, showing a potential alternative catalyst for ORR in fuel cells and air batteries.

A flexible CNT@nickel silicate composite film for high-performance sodium storage

Due to the sufficient ion diffusion channels provided by the large interlayer spacing, layered silicates are widely considered as potential anode materials for lithium ion and sodium ion batteries. However, due to the poor electronic conductivity, the application of layered silicates for electrochemical energy storage has been greatly limited. Carbon nanotube(CNT) film has excellent electrical conductivity and a unique interconnected network, making it an ideal matrix for composite electrochemical material. We herein report a CNT@nickel silicate composite film(CNT@NiSiO) fabricated by a SiO2-mediated hydrothermal conversion process, for sodium storage with excellent electrochemical properties. The obtained composite possesses a cladding structure with homogeneous nanosheets as the outermost and CNT film as the inner network matrix, providing abundant ion diffusion channels, high electronic conductivity, and good mechanical flexibility. Due to these merits, this material possesses an excellent electrochemical performance for sodium storage, including a high specific capacity up to 390 mAh g-1 at 50 mA g-1, good rate performance up to 205 mAh g-1 at 500 mA g-1, and excellent cycling stability. On this basis, this work would bring a promising material for various energy storage devices and other emerging applications.