Efficient bifunctional catalysts for oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)are vital for rechargeable Zn-air batteries(ZABs).Herein,an oxygen-respirable sponge-like Co@C–O–Cs catalyst with ...Efficient bifunctional catalysts for oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)are vital for rechargeable Zn-air batteries(ZABs).Herein,an oxygen-respirable sponge-like Co@C–O–Cs catalyst with oxygen-rich active sites was designed and constructed for both ORR and OER by a facile carbon dot-assisted strategy.The aerophilic triphase interface of Co@C–O–Cs cathode efficiently boosts oxygen diffusion and transfer.The theoretical calculations and experimental studies revealed that the Co–C–COC active sites can redistribute the local charge density and lower the reaction energy barrier.The Co@C–O–Cs catalyst displays superior bifunctional catalytic activities with a half-wave potential of 0.82 V for ORR and an ultralow overpotential of 294 mV at 10 mA cm^(−2) for OER.Moreover,it can drive the liquid ZABs with high peak power density(106.4 mW cm^(−2)),specific capacity(720.7 mAh g^(−1)),outstanding long-term cycle stability(over 750 cycles at 10 mA cm^(−2)),and exhibits excellent feasibility in flexible all-solid-state ZABs.These findings provide new insights into the rational design of efficient bifunctional oxygen catalysts in rechargeable metal-air batteries.展开更多
Carbon quantum dots(CQDs)as a new class of emerging materials have gradually drawn researchers’concern in recent years.In this work,the graphitic CQDs are prepared through a scalable approach,achieving a high yield w...Carbon quantum dots(CQDs)as a new class of emerging materials have gradually drawn researchers’concern in recent years.In this work,the graphitic CQDs are prepared through a scalable approach,achieving a high yield with more than 50%.The obtained CQDs are further used as structure-directing and conductive agents to synthesize novel N,S-CQDs/NiCo2S4 composite cathode materials,manifesting the enhanced electrochemical properties resulted from the synergistic effect of highly conductive N,S-codoped CQDs offering fast electronic transport and unique micro-/nanostructured NiCo2S4 microspheres with Faradaic redox characteristic contributing large capacity.Moreover,the nitrogen-doped reduced graphene oxide(N-rGO)/Fe2O3 composite anode materials exhibit ultrahigh specific capacity as well as significantly improved rate property and cycle performance originating from the high-capacity prism-like Fe2O3 hexahedrons tightly wrapped by highly conductive N-rGO.A novel alkaline aqueous battery assembled by these materials displays a specific energy(50.2 Wh kg^−1),ultrahigh specific power(9.7 kW kg^−1)and excellent cycling performance with 91.5%of capacity retention at 3 A g^−1 for 5000 cycles.The present research offers a valuable guidance for the exploitation of advanced energy storage devices by the rational design and selection of battery/capacitive composite materials.展开更多
The lack of methods to modulate intrinsic textures of carbon cathode has seriously hindered the revelation of in-depth relationship between inherent natures and capacitive behaviors,limiting the advancement of lithium...The lack of methods to modulate intrinsic textures of carbon cathode has seriously hindered the revelation of in-depth relationship between inherent natures and capacitive behaviors,limiting the advancement of lithium ion capacitors(LICs).Here,an orientateddesigned pore size distribution(range from 0.5 to 200 nm)and graphitization engineering strategy of carbon materials through regulating molar ratios of Zn/Co ions has been proposed,which provides an effective platform to deeply evaluate the capacitive behaviors of carbon cathode.Significantly,after the systematical analysis cooperating with experimental result and density functional theory calculation,it is uncovered that the size of solvated PF6-ion is about 1.5 nm.Moreover,the capacitive behaviors of carbon cathode could be enhanced attributed to the controlled pore size of 1.5-3 nm.Triggered with synergistic effect of graphitization and appropriate pore size distribution,optimized carbon cathode(Zn90Co10-APC)displays excellent capacitive performances with a reversible specific capacity of^50 mAh g-1at a current density of 5 A g-1.Furthermore,the assembly pre-lithiated graphite(PLG)//Zn90Co10-APC LIC could deliver a large energy density of 108 Wh kg-1 and a high power density of 150,000 W kg-1 as well as excellent long-term ability with 10,000 cycles.This elaborate work might shed light on the intensive understanding of the improved capacitive behavior in LiPF<sub>6 electrolyte and provide a feasible principle for elaborate fabrication of carbon cathodes for LIC systems.展开更多
Exploring new materials with high stability and capacity is full of challenges in sustainable energy conversion and storage systems.Metal-organic frameworks(MOFs),as a new type of porous material,show the advantages o...Exploring new materials with high stability and capacity is full of challenges in sustainable energy conversion and storage systems.Metal-organic frameworks(MOFs),as a new type of porous material,show the advantages of large specific surface area,high porosity,low density,and adjustable pore size,exhibiting a broad application prospect in the field of electrocatalytic reactions,batteries,particularly in the field of supercapacitors.This comprehensive review outlines the recent progress in synthetic methods and electrochemical performances of MOF materials,as well as their applications in supercapacitors.Additionally,the superiorities of MOFs-related materials are highlighted,while major challenges or opportunities for future research on them for electrochemical supercapacitors have been discussed and displayed,along with extensive experimental experiences.展开更多
All-solid-state lithium batteries(ASSLBs)are recognized as high energy density batteries system without safety issues within the next generation of batteries.The development of solid electrolytes is the crucial step o...All-solid-state lithium batteries(ASSLBs)are recognized as high energy density batteries system without safety issues within the next generation of batteries.The development of solid electrolytes is the crucial step of ASSLBs.The composite electrolyte has stable physical and electrochemical characteristics,and its comprehensive performance surpasses the individual solid electrolyte,bringing unique vitality to the solid electrolyte.However,their intrinsic weakness limits the development of composite electrolytes.In this review,we provide a comprehensive and in-depth understanding of the challenges and opportunities of composite electrolytes,with special focus on mechanisms of ion transport,nanostructure design towards high ionic conductivity,interfacial issues within electrolytes and electrodes.Furthermore,future development is prospected,which can shed light on researchers in this field and accelerate the industrial production of composite electrolytes.展开更多
High-performance lithium ion capacitors(LICs) have been seriously hindered by the very low capacity and unclear capacitive mechanism of carbon cathode.Herein,after the combination of experimental results and theoretic...High-performance lithium ion capacitors(LICs) have been seriously hindered by the very low capacity and unclear capacitive mechanism of carbon cathode.Herein,after the combination of experimental results and theoretical calculations,it is found that the critical pore size of 0.8 nm for PF_6~-ion adsorption decreases strong interactive repulsion of electrons and largely reduces adsorption energy barrier,which greatly improves the charge accommodation capacity in electrical double-layer behavior.Most importantly,the chemical-bond evolution process of C=O group has been firstly revealed by X-ray photoelectron spectroscopy(XPS),indicating that the introduction of C=O group can provide abundant redox active sites for PF_6~-ion adsorption accompanied with enhanced pseudocapacitive capacity.Attributed to the synergistic effect of dual capacitive mechanism,porous carbon sheet(PCS) cathode shows a reversible specific capacity of 53.6 mAh g^(-1) even at a high current density of 50 A g^(-1).Significantly,the quasisolid-state LIC manifests state-of-the-art electrochemical performances with an integrated maximum energy density of 163 Wh kg^(-1) and an outstanding power density of 15,000 W kg^(-1).This elaborate work promotes better fundamental understanding about capacitive mechanism of PF_6~-ion and offers a rational dual-capacitive strategy for the design of advanced carbon cathodes.展开更多
Carbon-based materials have attracted much interest as one of the promising anodes for sodium-ion batteries. However, low utilization of electrolyte and slow ion-transfer rate during electrochemical process hinder the...Carbon-based materials have attracted much interest as one of the promising anodes for sodium-ion batteries. However, low utilization of electrolyte and slow ion-transfer rate during electrochemical process hinder the further application of traditional bulk carbon. In order to enhance the diffusion kinetics and maintain the reversibility, hierarchical hollow carbon microbox was successfully prepared through a tunable bottom-up self-template routine for sodium-ion batteries. During annealing process, the morphology construction and activation happened synchronously. Based on that, a range of cross-linked porous nanosheet and hollow microbox were attained by manipulating reactant condition. The generation of texture and physical property are analyzed and are established linkages related to the electrochemical behavior. As results depicted in kinetic exploration and simulation based on cyclic voltammetry, the surfacecontrolled electrochemical behavior gradually turns to be the diffusion-controlled behavior as the hollow microbox evolves to porous nanosheet. The probable reason is that the rational microstructure/texture design leads to the accelerated diffusion kinetic procedure and the reduced concentration difference polarization. Sodium storage mechanism was deduced as reversible binding of Na-ions with local defects,including vacancies on sp2 graphitic layers, at the edges of flakes and other structural defects instead of intercalation. Bestowed by the morphology design, the broad pore width distribution, abundant defects/active sites and surface functionality, hollow microbox electrode delivers great electrochemical performances. This work is expected to propose a novel and effective strategy to prepare tunable hierarchical hollow carbon microbox and induce the fast kinetic of carbon anode material.展开更多
The application of Sb_(2)S_(3)with marvelous theoretical capacity for alkali metal-ion batteries is seriously limited by its poor electrical conductivity and low initial coulombic efficiency(ICE).In this work,natural ...The application of Sb_(2)S_(3)with marvelous theoretical capacity for alkali metal-ion batteries is seriously limited by its poor electrical conductivity and low initial coulombic efficiency(ICE).In this work,natural stibnite modified by carbon dots(Sb_(2)S_(3)@xCDs)is elaborately designed with high ICE.Greatly,chemical processes of local oxidation–partial reduction–deep coupling for stibnite reduction of CDs are clearly demonstrated,confirmed with in situ high-temperature X-ray diffraction.More impressively,the ICE for lithium-ion batteries(LIBs)is enhanced to 85%,through the effect of oxygen-rich carbon matrix on C–S bonds which inhibit the conversion of sulfur to sulfite,well supported by X-ray photoelectron spectroscopy characterization of solid electrolyte interphase layers helped with density functional theory calculations.Not than less,it is found that Sb–O–C bonds existed in the interface effectively promote the electronic conductivity and expedite ion transmission by reducing the bandgap and restraining the slip of the dislocation.As a result,the optimal sample delivers a tremendous reversible capacity of 660 mAh g^(−1)in LIBs at a high current rate of 5 A g^(−1).This work provides a new methodology for enhancing the electrochemical energy storage performance of metal sulfides,especially for improving the ICE.展开更多
P2-type Mn-based layered oxides are viewed as promising cathode materials for sodium ion battery by virtue of their high theoretical capacity.Considering that pure Na_(2/3)MnO_(2)suffers from poor cycling performances...P2-type Mn-based layered oxides are viewed as promising cathode materials for sodium ion battery by virtue of their high theoretical capacity.Considering that pure Na_(2/3)MnO_(2)suffers from poor cycling performances,Cu-substitution strategy is proposed to effectively alleviate this issue.However,the structural evolution mechanism of the Cu-containing samples still remains unclear.Herein,we propose that CuSubstitution P2-type Na_(0.66)Mn_(1-x)Cu_(x)O_(2)with enlarged lattice parameters are conducive to improving the interlayer structure stability through mitigating TMO_(2)slabs distortion.Proved by synchrotron XAS spectra and ex/in situ XRD,the expansion/contraction of MnO_6 octahedron is dramatically reduced with the increased Cu content,showing the facilitated Na ion diffusion.Furthermore,when the ratio of Cu to Mn reaches 1:4,the phase transition from P2 to P'2 type at the end of discharge can be suppressed,resulting in the improved interlayer skeleton stability.The Cu-containing samples with stable interlayer structure exhibit high capacity retention and outstanding rate performances(a capacity of 79.9 m Ah g^(-1)at 5C).This Cu-substitution strategy provides a promising approach to designing highly stable cathodes.展开更多
Spinel LiMn_(2)O_(4)is recognized as one of the most competitive cathode candidates for lithium-ion batteries ascribed to environmentally benign and rich sources.However,the wholesale application of LiMn_(2)O_(4)is pr...Spinel LiMn_(2)O_(4)is recognized as one of the most competitive cathode candidates for lithium-ion batteries ascribed to environmentally benign and rich sources.However,the wholesale application of LiMn_(2)O_(4)is predominately plagued by its severe capacity degradation,mainly associated with the innate Jahn-Teller effect.Herein,single-crystalline LiMn_(2)O_(4)with Eu^(3+) doping is rationally designed to mitigate the detrimental Jahn-Teller distortion by tuning the chemical environment of MnO_(6) octahedra and accommodating localized electron,based on the unique aspheric flexible 4f electron orbit of rare-earth metal ions.Notably,the stretching of MnO_(6) octahedron stemmed from the Jahn-Teller effect in Eu-doped LiMn_(2)O_(4)is effectively suppressed,confirmed by theoretical calculation.Meanwhile,the structural stability of the material has been significantly enhanced due to the robust Mn–O band coherency and weakened phase transition,proved by synchrotron radiation absorption spectrum and operando X-ray diffraction.The corresponding active cathode manifests superior long-cycle stability after 300 loops at 2C and displays only a 0.011%capacity drop per cycle even at 5C.Given this,this modification tactic sheds new light on achieving superior long-cycle performances by suppressing distortion in various cathode materials.展开更多
Carbonaceous materials have been regarded as highly promising anode candidates for potassium storage with their cost-effectiveness and environmental benignity.However,low specific capacity and difficulty in large-scal...Carbonaceous materials have been regarded as highly promising anode candidates for potassium storage with their cost-effectiveness and environmental benignity.However,low specific capacity and difficulty in large-scale synthesis largely hinder their further development.Herein,a thermal-induced potassium–carbon alloy phase(K_(x)C_(y))with the expanded interlayer spacing strategy is first put forward.Through in situ high-temperature X-ray diffraction,a K_(2)C_(2) phase is evoked by thermal energy during the in-situ carbonization process of carbon quantum dots intermediate derived from potassium-containing precursors,whereas no lithium or sodium–carbon alloy phase is observed from lithium/sodium-containing precursors.The asobtained ultra-thin carbon nanosheets achieve adjustable layer spacing,preparation in bulk,delivering reversible potassium storage of 403.4 mAh g^(−1) at 100 mA g^(−1) and 161.2 mAh g^(−1) even at 5.0 A g^(−1),which is one of the most impressive K-storage performances reported so far with great potential application.Furthermore,the assembled potassium-ion hybrid capacitor by combining the impressive CFMs-900 anode with the three-dimensional framework-activated carbon delivers a high energy-power density of 251.7 Wh kg^(−1) at 250Wkg^(−1) with long-term stability.This study opens a scalable avenue to realize the expanded interlayer spacing,which can be extended to other multicarboxyl potassium salts and can provide approach for the design of high-performance carbon anode materials for potassium storage.展开更多
Sacrificial pre-metallation strategy could compensate for the irreversible consumption of metal ions and reduce the potential of anode,thereby elevating the cycle performance as well as open-circuit voltage for full m...Sacrificial pre-metallation strategy could compensate for the irreversible consumption of metal ions and reduce the potential of anode,thereby elevating the cycle performance as well as open-circuit voltage for full metal ion capacitors(MICs).However,suffered from massive-dosage abuse,exorbitant decomposition potential,and side effects of decomposition residue,the wide application of sacrificial approach was restricted.Herein,assisted with density functional theory calculations,strongly coupled interface(M-O-C,M=Li/Na/K)and electron donating group have been put forward to regulate the band gap and highest occupied molecular orbital level of metal oxalate(M_(2)C_(2)O_(4)),reducing polarization phenomenon and Gibbs free energy required for decomposition,which eventually decrease the practical decomposition potential from 4.50 to 3.95 V.Remarkably,full sodium ion capacitors constituted of commercial materials(activated carbon//hard carbon)could deliver a prominent energy density of 118.2 Wh kg^(−1)as well as excellent cycle stability under an ultra-low dosage pre-sodiation reagent of 15-30 wt%(far less than currently 100 wt%).Noteworthily,decomposition mechanism of sacrificial compound and the relative influence on the system of MICs after pre-metallation were initially revealed by in situ differential electrochemical mass spectrometry,offering in-depth insights for comprehending the function of cathode additives.In addition,this breakthrough has been successfully utilized in high performance lithium/potassium ion capacitors with Li_(2)C_(2)O_(4)/K_(2)C_(2)O_(4) as pre-metallation reagent,which will convincingly promote the commercialization of MICs.展开更多
Na_(4)Fe_(3)(PO_(4))_(2)(P_(2)O_(7))(NFPP)is currently drawing increased attention as a sodium-ion batteries(SIBs)cathode due to the cost-effective and NASICON-type structure features.Owing to the sluggish electron an...Na_(4)Fe_(3)(PO_(4))_(2)(P_(2)O_(7))(NFPP)is currently drawing increased attention as a sodium-ion batteries(SIBs)cathode due to the cost-effective and NASICON-type structure features.Owing to the sluggish electron and Na~+conductivities,however,its real implementation is impeded by the grievous capacity decay and inferior rate capability.Herein,multivalent cation substituted microporous Na_(3.9)Fe_(2.9)Al_(0.1)(PO_(4))_(2)(P_(2)O_(7))(NFAPP)with wide operation-temperature is elaborately designed through regulating structure/interface coupled electron/ion transport.Greatly,the derived Na vacancy and charge rearrangement induced by trivalent Al^(3+)substitution lower the ions diffusion barriers,thereby endowing faster electron transport and Na^(+)mobility.More importantly,the existing Al-O-P bonds strengthen the local environment and alleviate the volume vibration during(de)sodiation,enabling highly reversible valence variation and structural evolution.As a result,remarkable cyclability(over 10,000 loops),ultrafast rate capability(200 C),and exceptional all-climate stability(-40-60℃)in half/full cells are demonstrated.Given this,the rational work might provide an actionable strategy to promote the electrochemical property of NFPP,thus unveiling the great application prospect of sodium iron mixed phosphate materials.展开更多
Rationally developing efficient and durable bifunctional catalysts toward oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)is critical for rechargeable zinc-air batteries(ZABs).Herein,a bead-like CoSe_(...Rationally developing efficient and durable bifunctional catalysts toward oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)is critical for rechargeable zinc-air batteries(ZABs).Herein,a bead-like CoSe_(2)@NC@NCNFs bifunctional catalyst was designed and fabricated by confining cubic CoSe_(2)nanoparticles to three-dimensional(3D)porous MOFs-derived nitrogen-doped carbon(NC)and one-dimensional(1D)N-doped carbon nanofibers(NCNFs)through a facile encapsulate strategy.The 1D/3D continuous network structure contributes to the improvement of specific surface area and electronic conductivity,while the strong synergistic effect between CoSe_(2)sites and Co-Nx-C sites can effectively enhance electron/mass transfer and reduce the diffusion resistance.The as-constructed CoSe_(2)@NC@NCNFs catalyst exhibits high catalytic activity and stability toward ORR/OER with a high half-wave potential of 0.80 V(vs.RHE)in ORR and a low overpotential of 280 mV at 10 mA·cm^(−2)in OER.More encouragingly,the rechargeable ZABs with CoSe_(2)@NC@NCNFs cathode deliver high peak power densities(126.8 mW·cm^(−2)),large specific capacities(763.1 mA·h·g^(−1)),and robust charge-discharge cycling stability over 240 cycles.This study provides a facile strategy for designing efficient bifunctional catalysts for rechargeable energy conversion applications.展开更多
Although lithium-sulfur(Li-S)batteries with high specific energy exhibit great potential for next-generation energy-storage systems,their practical applications are limited by the growth of Li dendrites and lithium po...Although lithium-sulfur(Li-S)batteries with high specific energy exhibit great potential for next-generation energy-storage systems,their practical applications are limited by the growth of Li dendrites and lithium polysulfides(LiPSs)shuttling.Herein,a highly porous red phosphorus sponge(HPPS)with well distributed pore structure was efficiently prepared via a facile and largescale hydrothermal process for polysulfides adsorption and dendrite suppression.As experimental demonstrated,the porous red phosphorus modified separator with increased active site greatly promotes the chemisorption of LiPSs to efficiently immobilize the active sulfur within the cathode section,while Li metal anode activated by Li_(3)P interlayer with abundant ionically conductive channels significantly eliminates the barrier for uniform Li^(+)permeation across the interlayer,contributing to the enhanced stability for both S cathode and Li anode.Mediated by the HPPS,long-term stability of 1,200 h with minor voltage hysteresis is achieved in symmetric cells with Li_(3)P@Li electrode while Li-S half-cell based on HPPS modified separator delivers an outperformed reversibility of 783.0 mAh·g^(−1)after 300 cycles as well as high-rate performance of 694.5 mAh·g^(−1)at 3 C,which further boosts the HPPS tuned full cells in practical S loading(3 mg·cm^(−2))and thin Li3P@Li electrode(100μm)with a capacity retention of 71.8%after 200 cycles at 0.5 C.This work provides a cost-effective and metal free mediator for simultaneously alleviating the fundamental issues of both S cathode and Li anode towards high energy density and long cycle life Li-S full batteries.展开更多
The severe dendrite growth on zinc anode in alkaline electrolyte brings great challenge to the development of zinc-based batteries.It is a simple and effective strategy to inhibit zinc dendrite formation by introducin...The severe dendrite growth on zinc anode in alkaline electrolyte brings great challenge to the development of zinc-based batteries.It is a simple and effective strategy to inhibit zinc dendrite formation by introducing additives into the electrolyte.In this study,N,S-doped carbon dots(TU-CQDs)were synthesized and used as additives to regulate zinc deposition in a typical KOH electrolyte.The experimental and three-dimensional transient nucleation model disclosed that the special functional groups of carbon dots can change the electrode surface state and the coordination behaviors of zinc species in the electrolyte.Therefore,TU-CQDs can not only inhibit the hydrogen evolution reaction,but also achieve uniform zinc deposition.The in-situ synchrotron radiation X-ray imaging elucidated that TU-CQDs can effectively inhibit the dendrite growth and improve the reversibility of zinc plating/stripping process.This work provides a feasible route for regulating the reversibility of zinc metal anode in alkaline electrolyte.展开更多
Titanium oxides have been considered promising anode materials for lithium-ion batteries(LIBs).However,the poor conductivity and low specific capacity of bulk titanium oxides limit their application.In this study,a ca...Titanium oxides have been considered promising anode materials for lithium-ion batteries(LIBs).However,the poor conductivity and low specific capacity of bulk titanium oxides limit their application.In this study,a carbon dot-modified TiO_(2)@SiO_(2)aerogel was successfully fabricated through a facile ambient pressure drying strategy and used as an anode material of LIBs.Benefiting from the crosslinking of carbon dots and the surface modification of SiO_(2),the as-prepared hierarchical aerogel exhibited a high initial discharge capacity of 974 mAh g^(−1)and maintained a capacity of 299 mAh g^(−1)after 100 cycles at 0.1 A g^(−1).It also retained a discharge capacity of 111 mAh g^(−1)with a CE of 99.9%at 3 A g^(−1).The carbon dot-modified cross-linking skeleton contributes to the structural integrity of the TiO_(2)@SiO_(2)aerogel during repeated insertion/extraction of lithium ions,guaranteeing outstanding cycling and high-rate performance.This ambient pressure drying strategy provides a facile and feasible way to produce high-performance aerogel anode materials for lithium-ion storage.展开更多
通过静电纺丝技术制备了纳米级Sb@CN纤维复合材料,是一种潜在的钾离子电池电极材料.研究结果表明,多孔纳米纤维框架结构与均匀分布的Sb纳米组分之间的协同作用可以有效加速离子迁移速率,并缓解K+嵌入过程中引起的体积膨胀,从而使Sb@CN...通过静电纺丝技术制备了纳米级Sb@CN纤维复合材料,是一种潜在的钾离子电池电极材料.研究结果表明,多孔纳米纤维框架结构与均匀分布的Sb纳米组分之间的协同作用可以有效加速离子迁移速率,并缓解K+嵌入过程中引起的体积膨胀,从而使Sb@CN纳米纤维电极表现出优异的钾储存性能.尤其是其长循环稳定性,在5000 m A g–1电流密度下, 1000次循环后,仍可获得212.7 m Ah g–1的可逆容量,此高循环稳定性是目前高性能钾离子电池应用的关键指标.展开更多
共价硫碳材料优异的储能性能逐渐引起人们的极大关注,然而,在电化学钠储存过程中,化学键的演变机制尚不清楚.本文以苯基磷酸作为碳源和催化剂,硫酸钠为硫源和模板,通过高温热处理,成功制备了具有大量共价键的硫碳材料(HCSC),其中硫主要...共价硫碳材料优异的储能性能逐渐引起人们的极大关注,然而,在电化学钠储存过程中,化学键的演变机制尚不清楚.本文以苯基磷酸作为碳源和催化剂,硫酸钠为硫源和模板,通过高温热处理,成功制备了具有大量共价键的硫碳材料(HCSC),其中硫主要以C–S–C和C–S–S–C的短链形式存在.值得注意的是,在储钠过程中,当循环电压低于0.6 V时,大多数桥键会发生电化学裂解,导致在接下来的CV测试中出现了两个可见的氧化还原峰.原位和非原位测试表明,在还原过程中形成了S^2-,同时碳骨架也发生了不可逆的异构化.因此,在接下来的循环过程中(0.01–3.0 V),裂解硫和异构化碳可以共同参与钠的存储.同样,应用于Na-S电池系统中,电压窗口为0.6–2.8 V,在宽电压窗口活化的HCSC也表现出较高的可逆容量(770 mA h g^-1at 300 mA g^-1).这一发现揭示了硫碳桥联化合物的储能机理,也为其他电极材料的表界面化学提供了新的启示.展开更多
基金supported by the National Key Research and Development Program of China(No.2019YFC1907801)National Natural Science Foundation of China(No.52174286)+1 种基金the Science and Technology Innovation Program of Hunan Province(2021RC3014)Innovation-Driven Project of Central South University(No.2020CX007)。
文摘Efficient bifunctional catalysts for oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)are vital for rechargeable Zn-air batteries(ZABs).Herein,an oxygen-respirable sponge-like Co@C–O–Cs catalyst with oxygen-rich active sites was designed and constructed for both ORR and OER by a facile carbon dot-assisted strategy.The aerophilic triphase interface of Co@C–O–Cs cathode efficiently boosts oxygen diffusion and transfer.The theoretical calculations and experimental studies revealed that the Co–C–COC active sites can redistribute the local charge density and lower the reaction energy barrier.The Co@C–O–Cs catalyst displays superior bifunctional catalytic activities with a half-wave potential of 0.82 V for ORR and an ultralow overpotential of 294 mV at 10 mA cm^(−2) for OER.Moreover,it can drive the liquid ZABs with high peak power density(106.4 mW cm^(−2)),specific capacity(720.7 mAh g^(−1)),outstanding long-term cycle stability(over 750 cycles at 10 mA cm^(−2)),and exhibits excellent feasibility in flexible all-solid-state ZABs.These findings provide new insights into the rational design of efficient bifunctional oxygen catalysts in rechargeable metal-air batteries.
基金financially supported by National Natural Science Foundation of China(21601057)Hunan Provincial Natural Science Foundation of China(2018JJ3116)Excellent Youth Fund of Hunan Provincial Education Department(18B298)
文摘Carbon quantum dots(CQDs)as a new class of emerging materials have gradually drawn researchers’concern in recent years.In this work,the graphitic CQDs are prepared through a scalable approach,achieving a high yield with more than 50%.The obtained CQDs are further used as structure-directing and conductive agents to synthesize novel N,S-CQDs/NiCo2S4 composite cathode materials,manifesting the enhanced electrochemical properties resulted from the synergistic effect of highly conductive N,S-codoped CQDs offering fast electronic transport and unique micro-/nanostructured NiCo2S4 microspheres with Faradaic redox characteristic contributing large capacity.Moreover,the nitrogen-doped reduced graphene oxide(N-rGO)/Fe2O3 composite anode materials exhibit ultrahigh specific capacity as well as significantly improved rate property and cycle performance originating from the high-capacity prism-like Fe2O3 hexahedrons tightly wrapped by highly conductive N-rGO.A novel alkaline aqueous battery assembled by these materials displays a specific energy(50.2 Wh kg^−1),ultrahigh specific power(9.7 kW kg^−1)and excellent cycling performance with 91.5%of capacity retention at 3 A g^−1 for 5000 cycles.The present research offers a valuable guidance for the exploitation of advanced energy storage devices by the rational design and selection of battery/capacitive composite materials.
基金financially supported by National Key Research and Development Program of China(2018YFC1901605)the National Postdoctoral Program for Innovative Talents(BX201600192)+1 种基金Hunan Provincial Science and Technology Plan(2017TP1001)Innovation Mover Program of Central South University(GCX20190893Y)。
文摘The lack of methods to modulate intrinsic textures of carbon cathode has seriously hindered the revelation of in-depth relationship between inherent natures and capacitive behaviors,limiting the advancement of lithium ion capacitors(LICs).Here,an orientateddesigned pore size distribution(range from 0.5 to 200 nm)and graphitization engineering strategy of carbon materials through regulating molar ratios of Zn/Co ions has been proposed,which provides an effective platform to deeply evaluate the capacitive behaviors of carbon cathode.Significantly,after the systematical analysis cooperating with experimental result and density functional theory calculation,it is uncovered that the size of solvated PF6-ion is about 1.5 nm.Moreover,the capacitive behaviors of carbon cathode could be enhanced attributed to the controlled pore size of 1.5-3 nm.Triggered with synergistic effect of graphitization and appropriate pore size distribution,optimized carbon cathode(Zn90Co10-APC)displays excellent capacitive performances with a reversible specific capacity of^50 mAh g-1at a current density of 5 A g-1.Furthermore,the assembly pre-lithiated graphite(PLG)//Zn90Co10-APC LIC could deliver a large energy density of 108 Wh kg-1 and a high power density of 150,000 W kg-1 as well as excellent long-term ability with 10,000 cycles.This elaborate work might shed light on the intensive understanding of the improved capacitive behavior in LiPF<sub>6 electrolyte and provide a feasible principle for elaborate fabrication of carbon cathodes for LIC systems.
基金supported by the National Natural Science Foundation of China(52004338,51622406,21673298)Scientific Research Fund of Hunan Provincial Education Department(21B0017).
文摘Exploring new materials with high stability and capacity is full of challenges in sustainable energy conversion and storage systems.Metal-organic frameworks(MOFs),as a new type of porous material,show the advantages of large specific surface area,high porosity,low density,and adjustable pore size,exhibiting a broad application prospect in the field of electrocatalytic reactions,batteries,particularly in the field of supercapacitors.This comprehensive review outlines the recent progress in synthetic methods and electrochemical performances of MOF materials,as well as their applications in supercapacitors.Additionally,the superiorities of MOFs-related materials are highlighted,while major challenges or opportunities for future research on them for electrochemical supercapacitors have been discussed and displayed,along with extensive experimental experiences.
基金financially supported by the National Natural Science Foundation of China(52074359,51904342,U19A2019)the Hunan Provincial Science and Technology Plan(2020JJ3048)+2 种基金the Science and Technology Innovation Program of Hunan Province(2020RC4005,2019RS1004)the science and technology plan key project of Hunan Province(2020GK2100)the Innovation Mover Program of Central South University(2020CX007)。
文摘All-solid-state lithium batteries(ASSLBs)are recognized as high energy density batteries system without safety issues within the next generation of batteries.The development of solid electrolytes is the crucial step of ASSLBs.The composite electrolyte has stable physical and electrochemical characteristics,and its comprehensive performance surpasses the individual solid electrolyte,bringing unique vitality to the solid electrolyte.However,their intrinsic weakness limits the development of composite electrolytes.In this review,we provide a comprehensive and in-depth understanding of the challenges and opportunities of composite electrolytes,with special focus on mechanisms of ion transport,nanostructure design towards high ionic conductivity,interfacial issues within electrolytes and electrodes.Furthermore,future development is prospected,which can shed light on researchers in this field and accelerate the industrial production of composite electrolytes.
基金financially supported by the National Key Research and Development Program of China (2018YFC1901605)the National Natural Science Foundation of China (52004338)+2 种基金the Hunan Provincial Natural Science Foundation of China (2020JJ5696)the Guangdong Provincial Department of Natural Resources (2020-011)the Fundamental Research Funds for the Central Universities of Central South University (2020zzts058)。
文摘High-performance lithium ion capacitors(LICs) have been seriously hindered by the very low capacity and unclear capacitive mechanism of carbon cathode.Herein,after the combination of experimental results and theoretical calculations,it is found that the critical pore size of 0.8 nm for PF_6~-ion adsorption decreases strong interactive repulsion of electrons and largely reduces adsorption energy barrier,which greatly improves the charge accommodation capacity in electrical double-layer behavior.Most importantly,the chemical-bond evolution process of C=O group has been firstly revealed by X-ray photoelectron spectroscopy(XPS),indicating that the introduction of C=O group can provide abundant redox active sites for PF_6~-ion adsorption accompanied with enhanced pseudocapacitive capacity.Attributed to the synergistic effect of dual capacitive mechanism,porous carbon sheet(PCS) cathode shows a reversible specific capacity of 53.6 mAh g^(-1) even at a high current density of 50 A g^(-1).Significantly,the quasisolid-state LIC manifests state-of-the-art electrochemical performances with an integrated maximum energy density of 163 Wh kg^(-1) and an outstanding power density of 15,000 W kg^(-1).This elaborate work promotes better fundamental understanding about capacitive mechanism of PF_6~-ion and offers a rational dual-capacitive strategy for the design of advanced carbon cathodes.
基金supported by National Postdoctoral Program for Innovative Talents (BX201600192)the National Natural Science Foundation of China (51904342,21673298)+2 种基金China Postdoctoral Science Foundation (2017M6203552)National Key Research and Development Program of China (2017YFB0102000,2018YFB0104200)Hunan Provincial Science and Technology Plan (2017TP1001)。
文摘Carbon-based materials have attracted much interest as one of the promising anodes for sodium-ion batteries. However, low utilization of electrolyte and slow ion-transfer rate during electrochemical process hinder the further application of traditional bulk carbon. In order to enhance the diffusion kinetics and maintain the reversibility, hierarchical hollow carbon microbox was successfully prepared through a tunable bottom-up self-template routine for sodium-ion batteries. During annealing process, the morphology construction and activation happened synchronously. Based on that, a range of cross-linked porous nanosheet and hollow microbox were attained by manipulating reactant condition. The generation of texture and physical property are analyzed and are established linkages related to the electrochemical behavior. As results depicted in kinetic exploration and simulation based on cyclic voltammetry, the surfacecontrolled electrochemical behavior gradually turns to be the diffusion-controlled behavior as the hollow microbox evolves to porous nanosheet. The probable reason is that the rational microstructure/texture design leads to the accelerated diffusion kinetic procedure and the reduced concentration difference polarization. Sodium storage mechanism was deduced as reversible binding of Na-ions with local defects,including vacancies on sp2 graphitic layers, at the edges of flakes and other structural defects instead of intercalation. Bestowed by the morphology design, the broad pore width distribution, abundant defects/active sites and surface functionality, hollow microbox electrode delivers great electrochemical performances. This work is expected to propose a novel and effective strategy to prepare tunable hierarchical hollow carbon microbox and induce the fast kinetic of carbon anode material.
基金financially supported by the National Natural Science Foundation of China (51904342, 52074359, U21A20284)Hunan Provincial Science and Technology Plan (2020JJ3048)the Science and Technology Innovation Program of Hunan Province (2021RC3014, 2020RC4005, 2019RS1004)
文摘The application of Sb_(2)S_(3)with marvelous theoretical capacity for alkali metal-ion batteries is seriously limited by its poor electrical conductivity and low initial coulombic efficiency(ICE).In this work,natural stibnite modified by carbon dots(Sb_(2)S_(3)@xCDs)is elaborately designed with high ICE.Greatly,chemical processes of local oxidation–partial reduction–deep coupling for stibnite reduction of CDs are clearly demonstrated,confirmed with in situ high-temperature X-ray diffraction.More impressively,the ICE for lithium-ion batteries(LIBs)is enhanced to 85%,through the effect of oxygen-rich carbon matrix on C–S bonds which inhibit the conversion of sulfur to sulfite,well supported by X-ray photoelectron spectroscopy characterization of solid electrolyte interphase layers helped with density functional theory calculations.Not than less,it is found that Sb–O–C bonds existed in the interface effectively promote the electronic conductivity and expedite ion transmission by reducing the bandgap and restraining the slip of the dislocation.As a result,the optimal sample delivers a tremendous reversible capacity of 660 mAh g^(−1)in LIBs at a high current rate of 5 A g^(−1).This work provides a new methodology for enhancing the electrochemical energy storage performance of metal sulfides,especially for improving the ICE.
基金financially supported by the Science and Technology Foundation of Guizhou Province(QKHZC[2020]2Y037)the Science and Technology Innovation Program of Hunan Province(2020RC4005,2019RS1004)the Innovation Mover Program of Central South University(2020CX007)。
文摘P2-type Mn-based layered oxides are viewed as promising cathode materials for sodium ion battery by virtue of their high theoretical capacity.Considering that pure Na_(2/3)MnO_(2)suffers from poor cycling performances,Cu-substitution strategy is proposed to effectively alleviate this issue.However,the structural evolution mechanism of the Cu-containing samples still remains unclear.Herein,we propose that CuSubstitution P2-type Na_(0.66)Mn_(1-x)Cu_(x)O_(2)with enlarged lattice parameters are conducive to improving the interlayer structure stability through mitigating TMO_(2)slabs distortion.Proved by synchrotron XAS spectra and ex/in situ XRD,the expansion/contraction of MnO_6 octahedron is dramatically reduced with the increased Cu content,showing the facilitated Na ion diffusion.Furthermore,when the ratio of Cu to Mn reaches 1:4,the phase transition from P2 to P'2 type at the end of discharge can be suppressed,resulting in the improved interlayer skeleton stability.The Cu-containing samples with stable interlayer structure exhibit high capacity retention and outstanding rate performances(a capacity of 79.9 m Ah g^(-1)at 5C).This Cu-substitution strategy provides a promising approach to designing highly stable cathodes.
基金financially supported by the National Natural Science Foundation of China(U21A20284)the National Key Research and Development Program of China(2019YFC1907805)the Fundamental Research Funds for the Central Universities of Central South University(2021zzts0072)。
文摘Spinel LiMn_(2)O_(4)is recognized as one of the most competitive cathode candidates for lithium-ion batteries ascribed to environmentally benign and rich sources.However,the wholesale application of LiMn_(2)O_(4)is predominately plagued by its severe capacity degradation,mainly associated with the innate Jahn-Teller effect.Herein,single-crystalline LiMn_(2)O_(4)with Eu^(3+) doping is rationally designed to mitigate the detrimental Jahn-Teller distortion by tuning the chemical environment of MnO_(6) octahedra and accommodating localized electron,based on the unique aspheric flexible 4f electron orbit of rare-earth metal ions.Notably,the stretching of MnO_(6) octahedron stemmed from the Jahn-Teller effect in Eu-doped LiMn_(2)O_(4)is effectively suppressed,confirmed by theoretical calculation.Meanwhile,the structural stability of the material has been significantly enhanced due to the robust Mn–O band coherency and weakened phase transition,proved by synchrotron radiation absorption spectrum and operando X-ray diffraction.The corresponding active cathode manifests superior long-cycle stability after 300 loops at 2C and displays only a 0.011%capacity drop per cycle even at 5C.Given this,this modification tactic sheds new light on achieving superior long-cycle performances by suppressing distortion in various cathode materials.
基金National Natural Science Foundation of China,Grant/Award Numbers:52004338,51904342,52074359Guangdong Provincial Department of Natural Resources,Grant/Award Number:2020-011Hunan Provincial Natural Science Foundation,Grant/Award Number:2020JJ5696。
文摘Carbonaceous materials have been regarded as highly promising anode candidates for potassium storage with their cost-effectiveness and environmental benignity.However,low specific capacity and difficulty in large-scale synthesis largely hinder their further development.Herein,a thermal-induced potassium–carbon alloy phase(K_(x)C_(y))with the expanded interlayer spacing strategy is first put forward.Through in situ high-temperature X-ray diffraction,a K_(2)C_(2) phase is evoked by thermal energy during the in-situ carbonization process of carbon quantum dots intermediate derived from potassium-containing precursors,whereas no lithium or sodium–carbon alloy phase is observed from lithium/sodium-containing precursors.The asobtained ultra-thin carbon nanosheets achieve adjustable layer spacing,preparation in bulk,delivering reversible potassium storage of 403.4 mAh g^(−1) at 100 mA g^(−1) and 161.2 mAh g^(−1) even at 5.0 A g^(−1),which is one of the most impressive K-storage performances reported so far with great potential application.Furthermore,the assembled potassium-ion hybrid capacitor by combining the impressive CFMs-900 anode with the three-dimensional framework-activated carbon delivers a high energy-power density of 251.7 Wh kg^(−1) at 250Wkg^(−1) with long-term stability.This study opens a scalable avenue to realize the expanded interlayer spacing,which can be extended to other multicarboxyl potassium salts and can provide approach for the design of high-performance carbon anode materials for potassium storage.
基金supported by the National Natural Science Foundation of China(52004338)the Hunan Provincial Natural Science Foundation of China(2020JJ5696)+2 种基金the Science,and Technology Innovation Program of Hunan Province(2020RC4005,2019RS1004)Guangdong Provincial Department of Natural Resources(2020-011)supported in part by the High Performance Computing Center of Central South University.
文摘Sacrificial pre-metallation strategy could compensate for the irreversible consumption of metal ions and reduce the potential of anode,thereby elevating the cycle performance as well as open-circuit voltage for full metal ion capacitors(MICs).However,suffered from massive-dosage abuse,exorbitant decomposition potential,and side effects of decomposition residue,the wide application of sacrificial approach was restricted.Herein,assisted with density functional theory calculations,strongly coupled interface(M-O-C,M=Li/Na/K)and electron donating group have been put forward to regulate the band gap and highest occupied molecular orbital level of metal oxalate(M_(2)C_(2)O_(4)),reducing polarization phenomenon and Gibbs free energy required for decomposition,which eventually decrease the practical decomposition potential from 4.50 to 3.95 V.Remarkably,full sodium ion capacitors constituted of commercial materials(activated carbon//hard carbon)could deliver a prominent energy density of 118.2 Wh kg^(−1)as well as excellent cycle stability under an ultra-low dosage pre-sodiation reagent of 15-30 wt%(far less than currently 100 wt%).Noteworthily,decomposition mechanism of sacrificial compound and the relative influence on the system of MICs after pre-metallation were initially revealed by in situ differential electrochemical mass spectrometry,offering in-depth insights for comprehending the function of cathode additives.In addition,this breakthrough has been successfully utilized in high performance lithium/potassium ion capacitors with Li_(2)C_(2)O_(4)/K_(2)C_(2)O_(4) as pre-metallation reagent,which will convincingly promote the commercialization of MICs.
基金supported by the National Natural Science Foundation of China(52325405,52261135632,and U21A20284)the Science and Technology Foundation of Guizhou Province(QKHZC[2020]2Y037)+1 种基金the Fundamental Research Funds for the Central Universities of Central South University(2023XQLH070,2023XQLH069)the U19 station in the National Synchrotron Radiation Laboratory(NSRL)。
文摘Na_(4)Fe_(3)(PO_(4))_(2)(P_(2)O_(7))(NFPP)is currently drawing increased attention as a sodium-ion batteries(SIBs)cathode due to the cost-effective and NASICON-type structure features.Owing to the sluggish electron and Na~+conductivities,however,its real implementation is impeded by the grievous capacity decay and inferior rate capability.Herein,multivalent cation substituted microporous Na_(3.9)Fe_(2.9)Al_(0.1)(PO_(4))_(2)(P_(2)O_(7))(NFAPP)with wide operation-temperature is elaborately designed through regulating structure/interface coupled electron/ion transport.Greatly,the derived Na vacancy and charge rearrangement induced by trivalent Al^(3+)substitution lower the ions diffusion barriers,thereby endowing faster electron transport and Na^(+)mobility.More importantly,the existing Al-O-P bonds strengthen the local environment and alleviate the volume vibration during(de)sodiation,enabling highly reversible valence variation and structural evolution.As a result,remarkable cyclability(over 10,000 loops),ultrafast rate capability(200 C),and exceptional all-climate stability(-40-60℃)in half/full cells are demonstrated.Given this,the rational work might provide an actionable strategy to promote the electrochemical property of NFPP,thus unveiling the great application prospect of sodium iron mixed phosphate materials.
基金supported by the National Natural Science Foundation of China(Nos.52174286,22105190)Natural Science Foundation of Hunan Province in China(2023JJ10068)Innovation-Driven Project of Central South University(No.2020CX007).
文摘Rationally developing efficient and durable bifunctional catalysts toward oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)is critical for rechargeable zinc-air batteries(ZABs).Herein,a bead-like CoSe_(2)@NC@NCNFs bifunctional catalyst was designed and fabricated by confining cubic CoSe_(2)nanoparticles to three-dimensional(3D)porous MOFs-derived nitrogen-doped carbon(NC)and one-dimensional(1D)N-doped carbon nanofibers(NCNFs)through a facile encapsulate strategy.The 1D/3D continuous network structure contributes to the improvement of specific surface area and electronic conductivity,while the strong synergistic effect between CoSe_(2)sites and Co-Nx-C sites can effectively enhance electron/mass transfer and reduce the diffusion resistance.The as-constructed CoSe_(2)@NC@NCNFs catalyst exhibits high catalytic activity and stability toward ORR/OER with a high half-wave potential of 0.80 V(vs.RHE)in ORR and a low overpotential of 280 mV at 10 mA·cm^(−2)in OER.More encouragingly,the rechargeable ZABs with CoSe_(2)@NC@NCNFs cathode deliver high peak power densities(126.8 mW·cm^(−2)),large specific capacities(763.1 mA·h·g^(−1)),and robust charge-discharge cycling stability over 240 cycles.This study provides a facile strategy for designing efficient bifunctional catalysts for rechargeable energy conversion applications.
基金supported by the National Natural Science Foundation of China(Nos.52074359,51904342,and U21A20284)the Hunan Provincial Science and Technology Plan(No.2020JJ3048)the Science and Technology Innovation Program of Hunan Province(Nos.2021RC3014,2020RC4005,and 2019RS1004).
文摘Although lithium-sulfur(Li-S)batteries with high specific energy exhibit great potential for next-generation energy-storage systems,their practical applications are limited by the growth of Li dendrites and lithium polysulfides(LiPSs)shuttling.Herein,a highly porous red phosphorus sponge(HPPS)with well distributed pore structure was efficiently prepared via a facile and largescale hydrothermal process for polysulfides adsorption and dendrite suppression.As experimental demonstrated,the porous red phosphorus modified separator with increased active site greatly promotes the chemisorption of LiPSs to efficiently immobilize the active sulfur within the cathode section,while Li metal anode activated by Li_(3)P interlayer with abundant ionically conductive channels significantly eliminates the barrier for uniform Li^(+)permeation across the interlayer,contributing to the enhanced stability for both S cathode and Li anode.Mediated by the HPPS,long-term stability of 1,200 h with minor voltage hysteresis is achieved in symmetric cells with Li_(3)P@Li electrode while Li-S half-cell based on HPPS modified separator delivers an outperformed reversibility of 783.0 mAh·g^(−1)after 300 cycles as well as high-rate performance of 694.5 mAh·g^(−1)at 3 C,which further boosts the HPPS tuned full cells in practical S loading(3 mg·cm^(−2))and thin Li3P@Li electrode(100μm)with a capacity retention of 71.8%after 200 cycles at 0.5 C.This work provides a cost-effective and metal free mediator for simultaneously alleviating the fundamental issues of both S cathode and Li anode towards high energy density and long cycle life Li-S full batteries.
基金financially supported by the National Key Research and Development Program of China(No.2019YFC1907801)Innovation-Driven Project of Central South University(No.2020CX007).
文摘The severe dendrite growth on zinc anode in alkaline electrolyte brings great challenge to the development of zinc-based batteries.It is a simple and effective strategy to inhibit zinc dendrite formation by introducing additives into the electrolyte.In this study,N,S-doped carbon dots(TU-CQDs)were synthesized and used as additives to regulate zinc deposition in a typical KOH electrolyte.The experimental and three-dimensional transient nucleation model disclosed that the special functional groups of carbon dots can change the electrode surface state and the coordination behaviors of zinc species in the electrolyte.Therefore,TU-CQDs can not only inhibit the hydrogen evolution reaction,but also achieve uniform zinc deposition.The in-situ synchrotron radiation X-ray imaging elucidated that TU-CQDs can effectively inhibit the dendrite growth and improve the reversibility of zinc plating/stripping process.This work provides a feasible route for regulating the reversibility of zinc metal anode in alkaline electrolyte.
基金supported by the National Key Research and Development Project(2019YFC1907801)the Innovation-Driven Project of Central South University(No.2020CX007).
文摘Titanium oxides have been considered promising anode materials for lithium-ion batteries(LIBs).However,the poor conductivity and low specific capacity of bulk titanium oxides limit their application.In this study,a carbon dot-modified TiO_(2)@SiO_(2)aerogel was successfully fabricated through a facile ambient pressure drying strategy and used as an anode material of LIBs.Benefiting from the crosslinking of carbon dots and the surface modification of SiO_(2),the as-prepared hierarchical aerogel exhibited a high initial discharge capacity of 974 mAh g^(−1)and maintained a capacity of 299 mAh g^(−1)after 100 cycles at 0.1 A g^(−1).It also retained a discharge capacity of 111 mAh g^(−1)with a CE of 99.9%at 3 A g^(−1).The carbon dot-modified cross-linking skeleton contributes to the structural integrity of the TiO_(2)@SiO_(2)aerogel during repeated insertion/extraction of lithium ions,guaranteeing outstanding cycling and high-rate performance.This ambient pressure drying strategy provides a facile and feasible way to produce high-performance aerogel anode materials for lithium-ion storage.
基金supported by the National Natural Science Foundation of China(51904342,51622406,and 21673298)the National Postdoctoral Program for Innovative Talents(BX201600192)+4 种基金Central South University Postdoctoral Foundation(140050018)China Postdoctoral Science Foundation(2017 M6203552)the National Key Research and Development Program of China(2017YFB0102000,2018YFB0104200)Hunan Provincial Science and Technology Plan(2017TP1001)the Fundamental Research Funds for the Central Universities of Central South University(2019zzts431,2019zzts433)。
文摘通过静电纺丝技术制备了纳米级Sb@CN纤维复合材料,是一种潜在的钾离子电池电极材料.研究结果表明,多孔纳米纤维框架结构与均匀分布的Sb纳米组分之间的协同作用可以有效加速离子迁移速率,并缓解K+嵌入过程中引起的体积膨胀,从而使Sb@CN纳米纤维电极表现出优异的钾储存性能.尤其是其长循环稳定性,在5000 m A g–1电流密度下, 1000次循环后,仍可获得212.7 m Ah g–1的可逆容量,此高循环稳定性是目前高性能钾离子电池应用的关键指标.
基金supported by the National Key Research and Development Program of China(2017YFB0102003 and2018YFB0104204)the National Natural Science Foundation of China(51622406,21673298 and 21473258)+2 种基金Young Elite Scientists Sponsorship Program By CAST(2017QNRC001)the Project of Innovation Driven Plan in Central South University(2017CX004 and 2018CX005)the Program for Innovative Team(in Science and Technology)in the University of Henan Province of China(17IRTSTHN003)
文摘共价硫碳材料优异的储能性能逐渐引起人们的极大关注,然而,在电化学钠储存过程中,化学键的演变机制尚不清楚.本文以苯基磷酸作为碳源和催化剂,硫酸钠为硫源和模板,通过高温热处理,成功制备了具有大量共价键的硫碳材料(HCSC),其中硫主要以C–S–C和C–S–S–C的短链形式存在.值得注意的是,在储钠过程中,当循环电压低于0.6 V时,大多数桥键会发生电化学裂解,导致在接下来的CV测试中出现了两个可见的氧化还原峰.原位和非原位测试表明,在还原过程中形成了S^2-,同时碳骨架也发生了不可逆的异构化.因此,在接下来的循环过程中(0.01–3.0 V),裂解硫和异构化碳可以共同参与钠的存储.同样,应用于Na-S电池系统中,电压窗口为0.6–2.8 V,在宽电压窗口活化的HCSC也表现出较高的可逆容量(770 mA h g^-1at 300 mA g^-1).这一发现揭示了硫碳桥联化合物的储能机理,也为其他电极材料的表界面化学提供了新的启示.
