Lithium sulfur(Li-S)batteries are the promising power sources,but their commercialization is significantly impeded by poor energy-storage functions at high sulfur loading.Here we report that such an issue can be effec...Lithium sulfur(Li-S)batteries are the promising power sources,but their commercialization is significantly impeded by poor energy-storage functions at high sulfur loading.Here we report that such an issue can be effectively addressed by using a mussel-inspired binder comprised of chitosan grafted with catecholic moiety for sulfur cathodes.The resulting sulfur cathodes possess a high loading up to 12.2 mg cm-2 but also exhibit one of the best electrochemical properties among their counterparts.The excellent performances are attributed to the strong adhesion of the binder to sulfur particles,conducting agent,current collector,and polysulfide.The versatile adhesion effectively increases the sulfur loading,depresses the shuttle effect,and alleviates mechanical pulverization during cycling processes.The present investigation offers a new insight into high performance sulfur cathodes through a bio-adhesion viewpoint.展开更多
Mesoporous LiFePO4/C composites containing 80 wt% of highly dispersed LiFePO4 nanoparticles(4-6 nm) were fabricated using bimodal mesoporous carbon(BMC) as continuous conductive networks. The unique pore structure of ...Mesoporous LiFePO4/C composites containing 80 wt% of highly dispersed LiFePO4 nanoparticles(4-6 nm) were fabricated using bimodal mesoporous carbon(BMC) as continuous conductive networks. The unique pore structure of BMC not only promises good particle connectivity for LiFePO4, but also acts as a rigid nano-confinement support that controls the particle size. Furthermore, the capacities were investigated respectively based on the weight of LiFePO4 and the whole composite. When calculated based on the weight of the whole composite, it is 120 mAh·g-1at 0.1 C of the high loading electrode and 42 mAh·g-1at 10 C of the low loading electrode. The electrochemical performance shows that high LiFePO4 loading benefits large tap density and contributes to the energy storage at low rates, while the electrode with low content of LiFePO4 displays superior high rate performance, which can mainly be due to the small particle size, good dispersion and high utilization of the active material, thus leading to a fast ion and electron diffusion.展开更多
The pursuit of high energy density has promoted the development of high-performance lithium metal batteries(LMBs).However,the underestimated but non-negligible dendrites of Li anode have been observed to shorten batte...The pursuit of high energy density has promoted the development of high-performance lithium metal batteries(LMBs).However,the underestimated but non-negligible dendrites of Li anode have been observed to shorten battery lifespan.Herein,a composite separator(TiO_(2-x)@PP),in which TiO_(2)with electron-localized oxygen vacancies(TiO_(2-x))is coated on a commercial PP separator,is fabricated to homogenize lithium ion transport and stabilize the lithium anode interface.With the utilization of TiO_(2-x)@PP separators,the symmetric lithium metal battery displays enhanced cycle stability over 800 h under a high current density of 8 m A cm^(-2).Moreover,the LMBs assembled with high-loading LiFePO_(4)(9.24 mg cm^(-2))deliver a stable cycling performance over 900 cycles at a rate of 0.5 C.Comprehensive theoretical studies based on density functional theory(DFT)further unveil the mechanism.The favorable TiO_(2-x)is beneficial for facilitating fast Li+migration and impeding anions transfer.In addressing the Li dendrite issues,the use of TiO_(2-x)@PP separator potentially provides a facile and attractive strategy for designing well-performing LMBs,which are expected to meet the application requirements of rechargeable batteries.展开更多
Lithium-sulfur(Li-S) batteries are one of the most promising rechargeable storage devices due to the high theoretical energy density.However,the low areal sulfur loading impedes their commercial development.Herein,a 3...Lithium-sulfur(Li-S) batteries are one of the most promising rechargeable storage devices due to the high theoretical energy density.However,the low areal sulfur loading impedes their commercial development.Herein,a 3 D free-standing sulfur cathode scaffold is rationally designed and fabricated by coaxially coating polar Ti_3 C_2 T_x flakes on sulfur-impregnated carbon cloth(Ti_3 C_2 T_x@S/CC) to achieve high loading and high energy density Li-S batteries,in which,the flexible CC substrate with highly porous structure can accommodate large amounts of sulfur and ensure fast electron transfer,while the outer-coated Ti_3 C_2 T_x can serve as a polar and conductive protective layer to further promote the conductivity of the whole electrode,achieve physical blocking and chemical anchoring of lithium-polysulfides as well as catalyze their conversion.Due to these advantages,at a sulfur loading of 4 mg cm^(-2),Li-S cells with Ti_3 C_2 T_x@S/CC cathodes can deliver outstanding cycling stability(746.1 mAh g^(-1) after 200 cycles at1 C),superb rate performance(866.8 mAh g^(-1) up to 2 C) and a high specific energy density(564.2 Wh kg^(-1) after 100 cycles at 0.5 C).More significantly,they also show the commercial potential that can compete with current lithium-ion batteries due to the high areal capacity of 6.7 mAh cm^(-2) at the increased loading of 8 mg cm^(-2).展开更多
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...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.展开更多
Electrochemical carbon dioxide reduction reaction(CO_(2)RR)provides an attractive approach to carbon capture and utilization for the production high-value-added products.However,CO_(2)RR still suffers from poor select...Electrochemical carbon dioxide reduction reaction(CO_(2)RR)provides an attractive approach to carbon capture and utilization for the production high-value-added products.However,CO_(2)RR still suffers from poor selectivity and low current density due to its sluggish kinetics and multitudinous reaction pathways.Single-atom catalysts(SACs)demonstrate outstanding activity,excellent selectivity,and remarkable atom utilization efficiency,which give impetus to the search for electrocatalytic processes aiming at high selectivity.There appears significant activity in the development of efficient SACs for CO_(2)RR,while the density of the atomic sites remains a considerable barrier to be overcome.To construct high-metal-loading SACs,aggregation must be prevented,and thus novel strategies are required.The key to creating high-density atomically dispersed sites is designing enough anchoring sites,normally defects,to stabilize the highly mobile separated metal atoms.In this review,we summarized the advances in developing high-loading SACs through defect engineering,with a focus on the synthesis strategies to achieve high atomic site loading.Finally,the future opportunities and challenges for CO_(2)RR in the area of high-loading single-atom electrocatalysts are also discussed.展开更多
On the base of controllable variable stiffness property,variable stiffness composites were the main components of functional materials in aerospace.However,the relatively low mechanical strength,stiffness range,and re...On the base of controllable variable stiffness property,variable stiffness composites were the main components of functional materials in aerospace.However,the relatively low mechanical strength,stiffness range,and response rate restricted the application of variable stiffness composite.In this work,the novel variable stiffness composite system with characteristics of repeatable high load bearing and response rate was successfully prepared via the double-layer anisotropic structure to solve the bottlenecks of variable stiffness composites.The novel variable stiffness composite systems were composed of variable stiffness layer of polycaprolactone(PCL)and the driven layer of silicone elastomer with alcohol,which continuously changed Young’s modulus from 0.1 to 7.263 MPa(72.63 times variation)in 200 s and maintained maximum weight of 11.52 times its own weight(8.5 g).Attributed to the relatively high variable stiffness range and load bearing value of variable stiffness composite system,the repeatable response process led to the efficient high load driven as“muscle”and diversified precise grab of objects with different shapes as“gripper”,owning widespread application prospects in the field of bionics.展开更多
High loading cathode with high active material proportion is a practical demand but far below the desirable value to achieve high energy density lithium-ion batteries(LIBs).Normally,the Li^(+)/electron transport betwe...High loading cathode with high active material proportion is a practical demand but far below the desirable value to achieve high energy density lithium-ion batteries(LIBs).Normally,the Li^(+)/electron transport between active materials and electrolyte/c arbon,however,it is poor and areal resistance is extremely high for a high loading/thick cathode.In this manuscript,taking high-voltage lithium cobalt oxide LiCoO_(2)(LCO)as an example,we design a facile liquid metal welding method enabled by a low melting-point indium-tin oxide In_(2)O_(3)/SnO_(2)(ITO)during a thermal treatment process,the strongly adhesion active particles show robust mechanical property for the free-standing LCO cathode with a pellet architecture.We also demonstrate that the O_(2)atmosphere plays a critical role on the interfacial property,that is preventing the layered structure to rock-salt Co_(3)O_(4)as well as further enhancing the interfacial mechanical integration.As expected,the LCO-ITO free-standing cathode not only shows robust mechanical property with densely packed configuration but also provides a fast Li^(+)/electron pathway at the interface.Consequently,the LCO-ITO composite cathode exhibits excellent electrochemical cycling performance in both liquid and solid-state cells.For example,even at a high active material mass of 56 mg·cm^(-2),the LCO cathode still delivers a specific capacity of 151 mAh·g^(-1)and maintains132.5 mAh·g^(-1)(corresponding to 7.4 mAh·cm^(-2))after 80cycles.The LCO-ITO-O_(2)cathode is also applicable to a solidstate cell,which exhibits a high capacity of 100.4 mAh·g^(-1)after 200 cycles of long-term cycling.The excellent electrochemical of the LCO-ITO-O_(2)reveals the successful engineering mechanical architecture and interfacial carriers transport,which may be expected as an alternative approach to achieve high energy density LIBs.展开更多
The practical application of lithium-sulfur(Li-S)batteries is greatly hindered by soluble polysulfides shuttling and sluggish sulfur redox kinetics.Rational design of multifunctional hybrid materials with superior ele...The practical application of lithium-sulfur(Li-S)batteries is greatly hindered by soluble polysulfides shuttling and sluggish sulfur redox kinetics.Rational design of multifunctional hybrid materials with superior electronic conductivity and high electrocatalytic activity,e.g.,heterostructures,is a promising strategy to solve the above obstacles.Herein,a binary metal sulfide MnS-MoS_(2) heterojunction electrocatalyst is first designed for the construction of high-sulfur-loaded and durable Li-S batteries.The MnS-MoS_(2) p-n heterojunction shows a unique structure of MoS_(2) nanosheets decorated with ample MnS nanodots,which contributes to the formation of a strong built-in electric field at the two-phase interface.The MnS-MoS_(2) hybrid host shows strong soluble polysulfide affinity,enhanced electronic conductivity,and exceptional catalytic effect on sulfur reduction.Benefiting from the synergistic effect,the as-derived S/MnS-MoS_(2) cathode delivers a superb rate capability(643 m A h g^(-1)at 6 C)and a durable cyclability(0.048%decay per cycle over 1000 cycles).More impressively,an areal capacity of 9.9 m A h cm^(-2)can be achieved even under an extremely high sulfur loading of 14.7 mg cm^(-2)and a low electrolyte to sulfur ratio of 2.9μL mg^(-1).This work provides an in-depth understanding of the interfacial catalytic effect of binary metal compound heterojunctions on sulfur reaction kinetics.展开更多
Drug delivery via intra-articular(IA)injection has proved to be effective in osteoarthritis(OA)therapy,limited by the drug efficiency and short retention time of the drug delivery systems(DDSs).Herein,a series of modi...Drug delivery via intra-articular(IA)injection has proved to be effective in osteoarthritis(OA)therapy,limited by the drug efficiency and short retention time of the drug delivery systems(DDSs).Herein,a series of modified cross-linked dextran(Sephadex,S0)was fabricated by respectively grafting with linear alkyl chains,branched alkyl chains or aromatic chain,and acted as DDSs after ibuprofen(Ibu)loading for OA therapy.This DDSs expressed sustained drug release,excellent anti-inflammatory and chondroprotective effects both in IL-1βinduced chondrocytes and OA joints.Specifically,the introduction of a longer hydrophobic chain,particularly an aromatic chain,distinctly improved the hydrophobicity of S0,increased Ibu loading efficiency,and further led to significantly improving OA therapeutic effects.Therefore,hydrophobic microspheres with greatly improved drug loading ratio and prolonged degradation rates show great potential to act as DDSs for OA therapy.展开更多
Controlled integration of ultrafine metal nanoparticles (MNPs) and metal- organic frameworks (MOFs) has drawn much attention due to their unique physical and chemical properties. However, the development of a one-...Controlled integration of ultrafine metal nanoparticles (MNPs) and metal- organic frameworks (MOFs) has drawn much attention due to their unique physical and chemical properties. However, the development of a one-step strategy for preparing ultrafine MNPs within MOFs still remains a great challenge. Herein, a facile synthetic approach toward the abovementioned composites was developed. In contrast to the conventional approach, these hybrids were prepared by the direct mixing of metal and MOF precursors in the reaction solution assisted by microwave irradiation. Impressively, the Au/MOF-199 composite with uniformly distributed ultrafine Au nanoparticles could be fabricated in only two minutes, and the Au loading could be increased up to a level of 5.13%. The multifunctional Au/MOF-199 catalysts exhibited high turnover numbers (TONs) and turnover frequencies (TOFs) in the three-component coupling reaction of formaldehyde, phenylacetylene, and piperidine (AB-coupling). Owing to the confinement effect of MOF-199, the 5.13%Au/MOF-199 catalyst could be recycled for five runs without serious loss of activity, with no obvious aggregation of Au NPs detected.展开更多
Three-dimensionally(3D) ordered mesoporous carbon sphere arrays(OMCS) are explored to support high loading(60 wt%) Pt nanoparticles as electrocatalysts for the methanol oxidation reaction(MOR).The OMCS has a u...Three-dimensionally(3D) ordered mesoporous carbon sphere arrays(OMCS) are explored to support high loading(60 wt%) Pt nanoparticles as electrocatalysts for the methanol oxidation reaction(MOR).The OMCS has a unique hierarchical nanostructure with ordered large mesopores and macropores that can facilitate high dispersion of the Pt nanoparticles and fast mass transport during the reactions. The prepared Pt/OMCS exhibits uniformly dispersed Pt nanoparticles with an average size of- 2.0 nm on the mesoporous walls of the carbon spheres. The Pt/OMCS catalyst shows significantly enhanced specific electrochemically active surface area(ECSA)(73.5 m^2g^-1) and electrocatalytic activity(0.69 mA cm^-2)for the MOR compared with the commercial 60 wt% Pt/C catalyst.展开更多
Lithium–sulfur(Li–S)batteries have been recognized as promising substitutes for current energy-storage technologies owing to their exceptional advantages in very high-energy density and excellent material sustainabi...Lithium–sulfur(Li–S)batteries have been recognized as promising substitutes for current energy-storage technologies owing to their exceptional advantages in very high-energy density and excellent material sustainability.The cathode with high sulfur areal loading is vital for the practical applications of Li–S batteries with very high energy density.However,the high sulfur loading in an electrode results in poor rate and cycling performances of batteries in most cases.Herein,we used diameters of 5.0(D5)and 13.0(D13)mm to probe the effect of electrodes with different sizes on the rate and cycling performances under a high sulfur loading(4.5 mg cm^-2).The cell with D5 sulfur cathode exhibits better rate and cycling performances comparing with a large(D13)cathode.Both the high concentration of lithium polysulfides and corrosion of lithium metal anode impede rapid kinetics of sulfur redox reactions,which results in inferior battery performance of the Li–S cell with large diameter cathode.This work highlights the importance of rational matching of the large sulfur cathode with a high areal sulfur loading,carbon modified separators,organic electrolyte,and Li metal anode in a pouch cell,wherein the sulfur redox kinetics and lithium metal protection should be carefully considered under the flooded lithium polysulfide conditions in a working Li–S battery.展开更多
The lithium-sulfur battery is the subject of much recent attention due to the high theoretical energy density,but practical applications are challenged by fast decay owing to polysulfide shuttle and electrode architec...The lithium-sulfur battery is the subject of much recent attention due to the high theoretical energy density,but practical applications are challenged by fast decay owing to polysulfide shuttle and electrode architecture degradation.A comprehensive study of the sulfur host microstructure design and the cell architecture construction based on the MXene phase(Ti3C2Tx nanosheets) is performed,aiming at realize stable cycling performance of Li-S battery with high sulfur areal loading.The interwoven KB@Ti3C2Tx composite formed by self-assembly of MXene and Ktej en black,not only provides superior conductivity and maintains the electrode integrality bearing the volume expansion/shrinkage when used as the sulfur host,but also functions as an interlayer on separator to further retard the polysulfide cross-diffusion that possibly escaped from the cathode.The KB@Ti3C2Tx interlayer is only 0.28 mg cm-2 in areal loading and 3 μm in thickness,which accounts a little contribution to the thick sulfur electrode;thus,the impacts on the energy density is minimal.By coupling the robust KB@Ti3C2Tx cathode and the effective KB@Ti3C2Tx modified separator,a stable Li-S battery with high sulfur areal loading(5.6 mg cm-2) and high areal capacity(6.4 mAh cm-2) at relatively lean electrolyte is achieved.展开更多
To improve performance of membrane electrode assembly(MEA)at large current density region,efficient mass transfer at the cathode is desired,for which a feasible strategy is to lower catalyst layer thickness by constru...To improve performance of membrane electrode assembly(MEA)at large current density region,efficient mass transfer at the cathode is desired,for which a feasible strategy is to lower catalyst layer thickness by constructing high loading Pt-alloy catalysts on carbon.But the high loading may induce unwanted par-ticle aggregation.In this work,H-PtNi/C with 33%(mass)Pt loading on carbon and monodisperse distri-bution of 3.55 nm PtNi nanoparticles,was prepared by a bimodal-pore route.In electrocatalytic oxygen reduction reaction(ORR),H-PtNi/C displays an activity inferior to the low Pt loading catalyst L-PtNi/C(13.3%(mass))in the half-cell.While in H_(2)-0_(2) MEA,H-PtNi/C delivers the peak power density of 1.51 W·cm^(-2) and the mass transfer limiting current density of 4.4 A·cm^(-2),being 21%and 16%higher than those of L-PtNi/C(1.25 W·cm^(-2),3.8 A·cm^(-2))respectively,which can be ascribed to enhanced mass trans-fer brought by the thinner catalyst layer in the former.In addition,the same method can be used to pre-pare PtFe alloy catalyst with a high-Pt loading of 36%(mass).This work may lead to a range of catalyst materials for the large current density applications,such as fuel cell vehicles.展开更多
Rechargeable aqueous zinc-ion batteries(AZIBs)have their unique advantages of cost efficiency,high safety,and environmental friendliness.However,challenges facing the cathode materials include whether they can remain ...Rechargeable aqueous zinc-ion batteries(AZIBs)have their unique advantages of cost efficiency,high safety,and environmental friendliness.However,challenges facing the cathode materials include whether they can remain chemically stable in aqueous electrolyte and provide a robust structure for the storage of Zn2+.Here,we report on H11Al2V6O23.2@graphene(HAVO@G)with exceptionally large layer spacing of(001)plane(13.36?).The graphene-wrapped structure can keep the structure stable during discharge/charge process,thereby promoting the inhibition of the dissolution of elements in the aqueous electrolyte.While used as cathode for AZIBs,HAVO@G electrode delivers ideal rate performance(reversible capacity of 305.4,276.6,230.0,201.7,180.6 mAh g?1 at current densities between 1 and 10 A g?1).Remarkably,the electrode exhibits excellent and stable cycling stability even at a high loading mass of^15.7 mg cm?2,with an ideal reversible capacity of 131.7 mAh g?1 after 400 cycles at 2 A g?1.展开更多
Based on the pressure regulation circuit adopting electro-hydraulic proportional relief valve to control tension, a new type of electro-hydraulic compound control circuit with throttle control unit is presented, which...Based on the pressure regulation circuit adopting electro-hydraulic proportional relief valve to control tension, a new type of electro-hydraulic compound control circuit with throttle control unit is presented, which can obtain optimal dynamic damping ratio through real-time altering pressure-flow gain of the throttle control unit, improve the dynamic characteristic of tension follow-up control for the tension system with high inertia loads. Moreover, the characteristic when the cable linear velocity variation causes change of tension is investigated, and a compound control strategy is proposed. The theoretical analysis and experimental results show that the electro-hydraulic compound control circuit is effective and the characteristic of the compound control strategy is satisfactory.展开更多
Flexible supercapacitor electrodes with high mass loading are crucial for obtaining favorable electrochemical performance but still challenging due to sluggish electron and ion transport.Herein,rationally designed CNT...Flexible supercapacitor electrodes with high mass loading are crucial for obtaining favorable electrochemical performance but still challenging due to sluggish electron and ion transport.Herein,rationally designed CNT/MnO2/graphene-grafted carbon cloth electrodes are prepared by a“graft-deposit-coat”strategy.Due to the large surface area and good conductivity,graphene grafted on carbon cloth offers additional surface areas for the uniform deposition of MnO2(9.1 mg cm?2)and facilitates charge transfer.Meanwhile,the nanostructured MnO2 provides abundant electroactive sites and short ion transport distance,and CNT coated on MnO2 acts as interconnected conductive“highways”to accelerate the electron transport,significantly improving redox reaction kinetics.Benefiting from high mass loading of electroactive materials,favorable conductivity,and a porous structure,the electrode achieves large areal capacitances without compromising rate capability.The assembled asymmetric supercapacitor demonstrates a wide working voltage(2.2 V)and high energy density of 10.18 mWh cm?3.展开更多
The response of three-dimensional sample of Al, containing vacancy complex, under shear loading was simulated. The molecular dynamics method was used and interaction between atoms was described on the base of pseudopo...The response of three-dimensional sample of Al, containing vacancy complex, under shear loading was simulated. The molecular dynamics method was used and interaction between atoms was described on the base of pseudopotential theory Solitary waves were generated in the sample under mechanical loading. Their interaction with the vacancy complexes was shown to be able to initiate hot spot in that local region of the complexes. Some parameters of the hot spot as well as solitary waves were calculated. The initiation of the hot spot is accompanied with sufficient local structural relaxation.展开更多
Lithium-sulfur batteries(LSBs)are promising alternative energy storage devices to the commercial lithium-ion batteries.However,the LSBs have several limitations including the low electronic conductivity of sulfur(5...Lithium-sulfur batteries(LSBs)are promising alternative energy storage devices to the commercial lithium-ion batteries.However,the LSBs have several limitations including the low electronic conductivity of sulfur(5×10^-30S cm^-1),associated lithium polysulfides(PSs),and their migration from the cathode to the anode.In this study,a separator coated with a Ketjen black(KB)/Nafion composite was used in an LSB with a sulfur loading up to 7.88 mg cm^-2to mitigate the PS migration.A minimum specific capacity(Cs)loss of 0.06%was obtained at 0.2 C-rate at a high sulfur loading of 4.39 mg cm^-2.Furthermore,an initial areal capacity up to 6.70 mAh cm^-2 was obtained at a sulfur loading of 7.88 mg cm^-2.The low Cs loss and high areal capacity associated with the high sulfur loading are attributed to the large surface area of the KB and sulfonate group(SO3^-)of Nafion,respectively,which could physically and chemically trap the PSs.展开更多
基金supported by the National Natural Science Foundation of China(51473041)the Foundation for Innovative Research Groups of the National Natural Science Foundation of China(51521003)+2 种基金China Postdoctoral Science Foundation(no.2017M621262)Fundamental Research Funds for the Central Universities(No.HIT.NSRIF.201831)Postdoctoral Foundation of Hei long Jiang Province(LBH-Z17065)。
文摘Lithium sulfur(Li-S)batteries are the promising power sources,but their commercialization is significantly impeded by poor energy-storage functions at high sulfur loading.Here we report that such an issue can be effectively addressed by using a mussel-inspired binder comprised of chitosan grafted with catecholic moiety for sulfur cathodes.The resulting sulfur cathodes possess a high loading up to 12.2 mg cm-2 but also exhibit one of the best electrochemical properties among their counterparts.The excellent performances are attributed to the strong adhesion of the binder to sulfur particles,conducting agent,current collector,and polysulfide.The versatile adhesion effectively increases the sulfur loading,depresses the shuttle effect,and alleviates mechanical pulverization during cycling processes.The present investigation offers a new insight into high performance sulfur cathodes through a bio-adhesion viewpoint.
基金supported by the National Natural Science Foundation of China (NSFC 21103184)the Ph.D.Programs Foundation (20100041110017) of Ministry of Education of Chinathe Fundamental Research Funds for the Central Universities
文摘Mesoporous LiFePO4/C composites containing 80 wt% of highly dispersed LiFePO4 nanoparticles(4-6 nm) were fabricated using bimodal mesoporous carbon(BMC) as continuous conductive networks. The unique pore structure of BMC not only promises good particle connectivity for LiFePO4, but also acts as a rigid nano-confinement support that controls the particle size. Furthermore, the capacities were investigated respectively based on the weight of LiFePO4 and the whole composite. When calculated based on the weight of the whole composite, it is 120 mAh·g-1at 0.1 C of the high loading electrode and 42 mAh·g-1at 10 C of the low loading electrode. The electrochemical performance shows that high LiFePO4 loading benefits large tap density and contributes to the energy storage at low rates, while the electrode with low content of LiFePO4 displays superior high rate performance, which can mainly be due to the small particle size, good dispersion and high utilization of the active material, thus leading to a fast ion and electron diffusion.
基金financial support provided by the National Natural Science Foundation of China(52064049)the Key National Natural Science Foundation of Yunnan Province(2018FA028 and 2019FY003023)+1 种基金the International Joint Research Center for Advanced Energy Materials of Yunnan Province(202003AE140001)the Key Laboratory of Solid State Ions for Green Energy of Yunnan University(2019),the Analysis and Measurements Center of Yunnan University for the sample testing service,and the Postgraduate Research and Innovation Foundation of Yunnan University(2021Y348)。
文摘The pursuit of high energy density has promoted the development of high-performance lithium metal batteries(LMBs).However,the underestimated but non-negligible dendrites of Li anode have been observed to shorten battery lifespan.Herein,a composite separator(TiO_(2-x)@PP),in which TiO_(2)with electron-localized oxygen vacancies(TiO_(2-x))is coated on a commercial PP separator,is fabricated to homogenize lithium ion transport and stabilize the lithium anode interface.With the utilization of TiO_(2-x)@PP separators,the symmetric lithium metal battery displays enhanced cycle stability over 800 h under a high current density of 8 m A cm^(-2).Moreover,the LMBs assembled with high-loading LiFePO_(4)(9.24 mg cm^(-2))deliver a stable cycling performance over 900 cycles at a rate of 0.5 C.Comprehensive theoretical studies based on density functional theory(DFT)further unveil the mechanism.The favorable TiO_(2-x)is beneficial for facilitating fast Li+migration and impeding anions transfer.In addressing the Li dendrite issues,the use of TiO_(2-x)@PP separator potentially provides a facile and attractive strategy for designing well-performing LMBs,which are expected to meet the application requirements of rechargeable batteries.
基金supported by the National Natural Science Foundation of China (51772069)。
文摘Lithium-sulfur(Li-S) batteries are one of the most promising rechargeable storage devices due to the high theoretical energy density.However,the low areal sulfur loading impedes their commercial development.Herein,a 3 D free-standing sulfur cathode scaffold is rationally designed and fabricated by coaxially coating polar Ti_3 C_2 T_x flakes on sulfur-impregnated carbon cloth(Ti_3 C_2 T_x@S/CC) to achieve high loading and high energy density Li-S batteries,in which,the flexible CC substrate with highly porous structure can accommodate large amounts of sulfur and ensure fast electron transfer,while the outer-coated Ti_3 C_2 T_x can serve as a polar and conductive protective layer to further promote the conductivity of the whole electrode,achieve physical blocking and chemical anchoring of lithium-polysulfides as well as catalyze their conversion.Due to these advantages,at a sulfur loading of 4 mg cm^(-2),Li-S cells with Ti_3 C_2 T_x@S/CC cathodes can deliver outstanding cycling stability(746.1 mAh g^(-1) after 200 cycles at1 C),superb rate performance(866.8 mAh g^(-1) up to 2 C) and a high specific energy density(564.2 Wh kg^(-1) after 100 cycles at 0.5 C).More significantly,they also show the commercial potential that can compete with current lithium-ion batteries due to the high areal capacity of 6.7 mAh cm^(-2) at the increased loading of 8 mg cm^(-2).
基金Korea Institute of Energy Technology Evaluation and Planning,Grant/Award Number:20214000000320Samsung Research Funding&Incubation Center of Samsung Electronics,Grant/Award Number:SRFC-MA1901-06。
文摘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.
基金This project was supported by the National Natural Science Foundation of China(U19A2017,22272206,51976143)Natural Science Foundation of Hunan Province(S2021JJMSXM3153).
文摘Electrochemical carbon dioxide reduction reaction(CO_(2)RR)provides an attractive approach to carbon capture and utilization for the production high-value-added products.However,CO_(2)RR still suffers from poor selectivity and low current density due to its sluggish kinetics and multitudinous reaction pathways.Single-atom catalysts(SACs)demonstrate outstanding activity,excellent selectivity,and remarkable atom utilization efficiency,which give impetus to the search for electrocatalytic processes aiming at high selectivity.There appears significant activity in the development of efficient SACs for CO_(2)RR,while the density of the atomic sites remains a considerable barrier to be overcome.To construct high-metal-loading SACs,aggregation must be prevented,and thus novel strategies are required.The key to creating high-density atomically dispersed sites is designing enough anchoring sites,normally defects,to stabilize the highly mobile separated metal atoms.In this review,we summarized the advances in developing high-loading SACs through defect engineering,with a focus on the synthesis strategies to achieve high atomic site loading.Finally,the future opportunities and challenges for CO_(2)RR in the area of high-loading single-atom electrocatalysts are also discussed.
基金the project of the National Key Research and Development Program of China(2018YFA0703300)the National Natural Science Foundation of China(52105302,52175271,52021003,and 91848204)+1 种基金the team of Innovation and entrepreneurship of Jilin Province(20210509047RQ,20210508057RQ)the Program for JLU Science and Technology Innovative Research Team(2017TD-04).
文摘On the base of controllable variable stiffness property,variable stiffness composites were the main components of functional materials in aerospace.However,the relatively low mechanical strength,stiffness range,and response rate restricted the application of variable stiffness composite.In this work,the novel variable stiffness composite system with characteristics of repeatable high load bearing and response rate was successfully prepared via the double-layer anisotropic structure to solve the bottlenecks of variable stiffness composites.The novel variable stiffness composite systems were composed of variable stiffness layer of polycaprolactone(PCL)and the driven layer of silicone elastomer with alcohol,which continuously changed Young’s modulus from 0.1 to 7.263 MPa(72.63 times variation)in 200 s and maintained maximum weight of 11.52 times its own weight(8.5 g).Attributed to the relatively high variable stiffness range and load bearing value of variable stiffness composite system,the repeatable response process led to the efficient high load driven as“muscle”and diversified precise grab of objects with different shapes as“gripper”,owning widespread application prospects in the field of bionics.
基金financially supported by the National Natural Science Foundation of China(Nos.22209075,51902165)the Natural Science Foundation of Jiangsu Province(No.BK20200800)。
文摘High loading cathode with high active material proportion is a practical demand but far below the desirable value to achieve high energy density lithium-ion batteries(LIBs).Normally,the Li^(+)/electron transport between active materials and electrolyte/c arbon,however,it is poor and areal resistance is extremely high for a high loading/thick cathode.In this manuscript,taking high-voltage lithium cobalt oxide LiCoO_(2)(LCO)as an example,we design a facile liquid metal welding method enabled by a low melting-point indium-tin oxide In_(2)O_(3)/SnO_(2)(ITO)during a thermal treatment process,the strongly adhesion active particles show robust mechanical property for the free-standing LCO cathode with a pellet architecture.We also demonstrate that the O_(2)atmosphere plays a critical role on the interfacial property,that is preventing the layered structure to rock-salt Co_(3)O_(4)as well as further enhancing the interfacial mechanical integration.As expected,the LCO-ITO free-standing cathode not only shows robust mechanical property with densely packed configuration but also provides a fast Li^(+)/electron pathway at the interface.Consequently,the LCO-ITO composite cathode exhibits excellent electrochemical cycling performance in both liquid and solid-state cells.For example,even at a high active material mass of 56 mg·cm^(-2),the LCO cathode still delivers a specific capacity of 151 mAh·g^(-1)and maintains132.5 mAh·g^(-1)(corresponding to 7.4 mAh·cm^(-2))after 80cycles.The LCO-ITO-O_(2)cathode is also applicable to a solidstate cell,which exhibits a high capacity of 100.4 mAh·g^(-1)after 200 cycles of long-term cycling.The excellent electrochemical of the LCO-ITO-O_(2)reveals the successful engineering mechanical architecture and interfacial carriers transport,which may be expected as an alternative approach to achieve high energy density LIBs.
基金financial support from the National Natural Science Foundation of China (NSFC,21875155,22032004)the support of the National Key Research and Development Program of China (2021YFA1201502)the support of the Nanqiang Young Top-notch Talent Fellowship in Xiamen University。
文摘The practical application of lithium-sulfur(Li-S)batteries is greatly hindered by soluble polysulfides shuttling and sluggish sulfur redox kinetics.Rational design of multifunctional hybrid materials with superior electronic conductivity and high electrocatalytic activity,e.g.,heterostructures,is a promising strategy to solve the above obstacles.Herein,a binary metal sulfide MnS-MoS_(2) heterojunction electrocatalyst is first designed for the construction of high-sulfur-loaded and durable Li-S batteries.The MnS-MoS_(2) p-n heterojunction shows a unique structure of MoS_(2) nanosheets decorated with ample MnS nanodots,which contributes to the formation of a strong built-in electric field at the two-phase interface.The MnS-MoS_(2) hybrid host shows strong soluble polysulfide affinity,enhanced electronic conductivity,and exceptional catalytic effect on sulfur reduction.Benefiting from the synergistic effect,the as-derived S/MnS-MoS_(2) cathode delivers a superb rate capability(643 m A h g^(-1)at 6 C)and a durable cyclability(0.048%decay per cycle over 1000 cycles).More impressively,an areal capacity of 9.9 m A h cm^(-2)can be achieved even under an extremely high sulfur loading of 14.7 mg cm^(-2)and a low electrolyte to sulfur ratio of 2.9μL mg^(-1).This work provides an in-depth understanding of the interfacial catalytic effect of binary metal compound heterojunctions on sulfur reaction kinetics.
基金supported by National Natural Science Foundation of China(Grant No.82160430)Natural Science Foundation of Guangxi(Grant No.2020GXNSFAA159134 and 2019GXNSFAA185060)+1 种基金Guangxi Science and Technology Base and Talent Special Project(Grant No.GuikeAD19254003 and GuikeAD21075002)Nanning Qingxiu District Science and Technology Major Special Project(Grant No.2020013).
文摘Drug delivery via intra-articular(IA)injection has proved to be effective in osteoarthritis(OA)therapy,limited by the drug efficiency and short retention time of the drug delivery systems(DDSs).Herein,a series of modified cross-linked dextran(Sephadex,S0)was fabricated by respectively grafting with linear alkyl chains,branched alkyl chains or aromatic chain,and acted as DDSs after ibuprofen(Ibu)loading for OA therapy.This DDSs expressed sustained drug release,excellent anti-inflammatory and chondroprotective effects both in IL-1βinduced chondrocytes and OA joints.Specifically,the introduction of a longer hydrophobic chain,particularly an aromatic chain,distinctly improved the hydrophobicity of S0,increased Ibu loading efficiency,and further led to significantly improving OA therapeutic effects.Therefore,hydrophobic microspheres with greatly improved drug loading ratio and prolonged degradation rates show great potential to act as DDSs for OA therapy.
基金The authors acknowledge the financial support from the National Natural Science Foundation of China (Nos. 21573286, 21173269, and 21572688), Ministry ofScience and Technology of China (Nos. 2011BAK15B05 and 2015AA034603), Specialized Research Fund for the Doctoral Program of Higher Education (No. 20130007110003), and Science Foundation of China University of Petroleum, Beijing (No. 2462015YQ0304).
文摘Controlled integration of ultrafine metal nanoparticles (MNPs) and metal- organic frameworks (MOFs) has drawn much attention due to their unique physical and chemical properties. However, the development of a one-step strategy for preparing ultrafine MNPs within MOFs still remains a great challenge. Herein, a facile synthetic approach toward the abovementioned composites was developed. In contrast to the conventional approach, these hybrids were prepared by the direct mixing of metal and MOF precursors in the reaction solution assisted by microwave irradiation. Impressively, the Au/MOF-199 composite with uniformly distributed ultrafine Au nanoparticles could be fabricated in only two minutes, and the Au loading could be increased up to a level of 5.13%. The multifunctional Au/MOF-199 catalysts exhibited high turnover numbers (TONs) and turnover frequencies (TOFs) in the three-component coupling reaction of formaldehyde, phenylacetylene, and piperidine (AB-coupling). Owing to the confinement effect of MOF-199, the 5.13%Au/MOF-199 catalyst could be recycled for five runs without serious loss of activity, with no obvious aggregation of Au NPs detected.
基金financial support from the National Natural Science Foundation of China (No. 51172014)the National 973 Program of China (No. 2009CB219903)the Scientific Innovation Grant for Excellent Young Scientists of Hebei University of Technology (No. 2015001)
文摘Three-dimensionally(3D) ordered mesoporous carbon sphere arrays(OMCS) are explored to support high loading(60 wt%) Pt nanoparticles as electrocatalysts for the methanol oxidation reaction(MOR).The OMCS has a unique hierarchical nanostructure with ordered large mesopores and macropores that can facilitate high dispersion of the Pt nanoparticles and fast mass transport during the reactions. The prepared Pt/OMCS exhibits uniformly dispersed Pt nanoparticles with an average size of- 2.0 nm on the mesoporous walls of the carbon spheres. The Pt/OMCS catalyst shows significantly enhanced specific electrochemically active surface area(ECSA)(73.5 m^2g^-1) and electrocatalytic activity(0.69 mA cm^-2)for the MOR compared with the commercial 60 wt% Pt/C catalyst.
基金supported by the National Key Research and Development Program(2016YFA0202500 and 2016YFA0200102)the National Natural Science Foundation of China(21776019,21805162,51772069,and U1801257)+1 种基金China Postdoctoral Science Foundation(2018M630165)Beijing Key Research and Development Plan(Z181100004518001)
文摘Lithium–sulfur(Li–S)batteries have been recognized as promising substitutes for current energy-storage technologies owing to their exceptional advantages in very high-energy density and excellent material sustainability.The cathode with high sulfur areal loading is vital for the practical applications of Li–S batteries with very high energy density.However,the high sulfur loading in an electrode results in poor rate and cycling performances of batteries in most cases.Herein,we used diameters of 5.0(D5)and 13.0(D13)mm to probe the effect of electrodes with different sizes on the rate and cycling performances under a high sulfur loading(4.5 mg cm^-2).The cell with D5 sulfur cathode exhibits better rate and cycling performances comparing with a large(D13)cathode.Both the high concentration of lithium polysulfides and corrosion of lithium metal anode impede rapid kinetics of sulfur redox reactions,which results in inferior battery performance of the Li–S cell with large diameter cathode.This work highlights the importance of rational matching of the large sulfur cathode with a high areal sulfur loading,carbon modified separators,organic electrolyte,and Li metal anode in a pouch cell,wherein the sulfur redox kinetics and lithium metal protection should be carefully considered under the flooded lithium polysulfide conditions in a working Li–S battery.
基金financially supported by National Key Research and Development Program(No.2019YFA0210600)the Major Technological Innovation Project of Hubei Science and Technology Department(No.2019AAA164)+1 种基金the National Natural Science Foundation of China(No.51972107)the Innovative Research Groups of Hunan Province(No.2019JJ10001)。
文摘The lithium-sulfur battery is the subject of much recent attention due to the high theoretical energy density,but practical applications are challenged by fast decay owing to polysulfide shuttle and electrode architecture degradation.A comprehensive study of the sulfur host microstructure design and the cell architecture construction based on the MXene phase(Ti3C2Tx nanosheets) is performed,aiming at realize stable cycling performance of Li-S battery with high sulfur areal loading.The interwoven KB@Ti3C2Tx composite formed by self-assembly of MXene and Ktej en black,not only provides superior conductivity and maintains the electrode integrality bearing the volume expansion/shrinkage when used as the sulfur host,but also functions as an interlayer on separator to further retard the polysulfide cross-diffusion that possibly escaped from the cathode.The KB@Ti3C2Tx interlayer is only 0.28 mg cm-2 in areal loading and 3 μm in thickness,which accounts a little contribution to the thick sulfur electrode;thus,the impacts on the energy density is minimal.By coupling the robust KB@Ti3C2Tx cathode and the effective KB@Ti3C2Tx modified separator,a stable Li-S battery with high sulfur areal loading(5.6 mg cm-2) and high areal capacity(6.4 mAh cm-2) at relatively lean electrolyte is achieved.
基金financially supported by the National Key Research and Development Program of China (2019YFB1504503)the National Natural Science Foundation of China (21878030 and 21761162015)
文摘To improve performance of membrane electrode assembly(MEA)at large current density region,efficient mass transfer at the cathode is desired,for which a feasible strategy is to lower catalyst layer thickness by constructing high loading Pt-alloy catalysts on carbon.But the high loading may induce unwanted par-ticle aggregation.In this work,H-PtNi/C with 33%(mass)Pt loading on carbon and monodisperse distri-bution of 3.55 nm PtNi nanoparticles,was prepared by a bimodal-pore route.In electrocatalytic oxygen reduction reaction(ORR),H-PtNi/C displays an activity inferior to the low Pt loading catalyst L-PtNi/C(13.3%(mass))in the half-cell.While in H_(2)-0_(2) MEA,H-PtNi/C delivers the peak power density of 1.51 W·cm^(-2) and the mass transfer limiting current density of 4.4 A·cm^(-2),being 21%and 16%higher than those of L-PtNi/C(1.25 W·cm^(-2),3.8 A·cm^(-2))respectively,which can be ascribed to enhanced mass trans-fer brought by the thinner catalyst layer in the former.In addition,the same method can be used to pre-pare PtFe alloy catalyst with a high-Pt loading of 36%(mass).This work may lead to a range of catalyst materials for the large current density applications,such as fuel cell vehicles.
基金supported by National Natural Science Foundation of China(Nos.51972346,51932011,51802356,and 51872334)Innovation-Driven Project of Central South University(No.2018CX004).
文摘Rechargeable aqueous zinc-ion batteries(AZIBs)have their unique advantages of cost efficiency,high safety,and environmental friendliness.However,challenges facing the cathode materials include whether they can remain chemically stable in aqueous electrolyte and provide a robust structure for the storage of Zn2+.Here,we report on H11Al2V6O23.2@graphene(HAVO@G)with exceptionally large layer spacing of(001)plane(13.36?).The graphene-wrapped structure can keep the structure stable during discharge/charge process,thereby promoting the inhibition of the dissolution of elements in the aqueous electrolyte.While used as cathode for AZIBs,HAVO@G electrode delivers ideal rate performance(reversible capacity of 305.4,276.6,230.0,201.7,180.6 mAh g?1 at current densities between 1 and 10 A g?1).Remarkably,the electrode exhibits excellent and stable cycling stability even at a high loading mass of^15.7 mg cm?2,with an ideal reversible capacity of 131.7 mAh g?1 after 400 cycles at 2 A g?1.
基金This project is supported by National Natural Science Foundation of China (No.50475105).
文摘Based on the pressure regulation circuit adopting electro-hydraulic proportional relief valve to control tension, a new type of electro-hydraulic compound control circuit with throttle control unit is presented, which can obtain optimal dynamic damping ratio through real-time altering pressure-flow gain of the throttle control unit, improve the dynamic characteristic of tension follow-up control for the tension system with high inertia loads. Moreover, the characteristic when the cable linear velocity variation causes change of tension is investigated, and a compound control strategy is proposed. The theoretical analysis and experimental results show that the electro-hydraulic compound control circuit is effective and the characteristic of the compound control strategy is satisfactory.
基金supported by the Basic Science Research Program through the National Research Foundation of Korea(NRF)funded by the Ministry of Education(NRF2018R1D1A1B07051249)Nano Material Technology Development Program(NRF-2015M3A7B6027970)of MSIP/NRF and Center for Integrated Smart Sensors funded by the Ministry of Science,ICTFuture Planning,Republic of Korea,as Global Frontier Project(CISS-2012M3A6A6054186).
文摘Flexible supercapacitor electrodes with high mass loading are crucial for obtaining favorable electrochemical performance but still challenging due to sluggish electron and ion transport.Herein,rationally designed CNT/MnO2/graphene-grafted carbon cloth electrodes are prepared by a“graft-deposit-coat”strategy.Due to the large surface area and good conductivity,graphene grafted on carbon cloth offers additional surface areas for the uniform deposition of MnO2(9.1 mg cm?2)and facilitates charge transfer.Meanwhile,the nanostructured MnO2 provides abundant electroactive sites and short ion transport distance,and CNT coated on MnO2 acts as interconnected conductive“highways”to accelerate the electron transport,significantly improving redox reaction kinetics.Benefiting from high mass loading of electroactive materials,favorable conductivity,and a porous structure,the electrode achieves large areal capacitances without compromising rate capability.The assembled asymmetric supercapacitor demonstrates a wide working voltage(2.2 V)and high energy density of 10.18 mWh cm?3.
文摘The response of three-dimensional sample of Al, containing vacancy complex, under shear loading was simulated. The molecular dynamics method was used and interaction between atoms was described on the base of pseudopotential theory Solitary waves were generated in the sample under mechanical loading. Their interaction with the vacancy complexes was shown to be able to initiate hot spot in that local region of the complexes. Some parameters of the hot spot as well as solitary waves were calculated. The initiation of the hot spot is accompanied with sufficient local structural relaxation.
基金the Australian Government and University of Queensland for the research training program scholarship and research facilities used in this study.
文摘Lithium-sulfur batteries(LSBs)are promising alternative energy storage devices to the commercial lithium-ion batteries.However,the LSBs have several limitations including the low electronic conductivity of sulfur(5×10^-30S cm^-1),associated lithium polysulfides(PSs),and their migration from the cathode to the anode.In this study,a separator coated with a Ketjen black(KB)/Nafion composite was used in an LSB with a sulfur loading up to 7.88 mg cm^-2to mitigate the PS migration.A minimum specific capacity(Cs)loss of 0.06%was obtained at 0.2 C-rate at a high sulfur loading of 4.39 mg cm^-2.Furthermore,an initial areal capacity up to 6.70 mAh cm^-2 was obtained at a sulfur loading of 7.88 mg cm^-2.The low Cs loss and high areal capacity associated with the high sulfur loading are attributed to the large surface area of the KB and sulfonate group(SO3^-)of Nafion,respectively,which could physically and chemically trap the PSs.