The chemical activation of various precursors is effective for creating additional closed pores in hard carbons for sodium storage.However,the formation mechanism of closed pores under the influence of pore-forming ag...The chemical activation of various precursors is effective for creating additional closed pores in hard carbons for sodium storage.However,the formation mechanism of closed pores under the influence of pore-forming agents is not well understood.Herein,an effective chemical activation followed by a high-temperature self-healing strategy is employed to generate interconnected closed pores in lignin-derived hard carbon(HCs).By systematic experimental design combined with electron paramagnetic res-onance spectroscopy,it can be found that the content of free radicals in the carbon matrix influences the closure of open pores at high temperatures.Excessively high activation temperature(>700 C)leads to a low free radical concentration,making it difficult to achieve self-healing of open pores at high tempera-tures.By activation at 700°C,a balance between pore making and self-healing is achieved in the final hard carbon.A large number of free radicals triggers rapid growth and aggregation of carbon microcrys-tals,blocking pre-formed open micropores and creating additional interconnected closed pores in as-obtained hard carbons.As a result,the optimized carbon anode(LK-700-1300)delivers a high reversible capacity of 330.8 mA h g^(-1) at 0.03 A g^(-1),which is an increase of 86 mA h g^(-1) compared to the pristine lignin-derived carbon anode(L-700-1300),and exhibits a good rate performance(202.1 mA h g^(-1) at 1 A g^(-1)).This work provides a universal and effective guidance for tuning closed pores of hard carbons from otherprecursors.展开更多
N-doped porous carbon has been extensively investigated for broad electrochemical applications.The performance is significantly impacted by the electrochemical double layer(EDL),which is material dependent and hard to...N-doped porous carbon has been extensively investigated for broad electrochemical applications.The performance is significantly impacted by the electrochemical double layer(EDL),which is material dependent and hard to characterize.Limited understanding of doping-derived EDL structure hinders insight into the structure-performance relations and the rational design of high-performance materials.Thus,we analyzed the mass and chemical composition variation of EDL within electrochemical operation by electrochemical quartz crystal microbalance,in-situ X-ray photoelectron spectroscopy,and time-offlight secondary ion mass spectrometry.We found that N-doping triggers specifically adsorbed propylene carbonate solvent in the inner Helmholtz plane(IHP),which prevents ion rearrangement and enhances the migration of cations.However,this specific adsorption accelerated solvent decomposition,rendering rapid performance degradation in practical devices.This work reveals that the surface chemistry of electrodes can cause specific adsorption of solvents and change the EDL structure,which complements the classical EDL theory and provide guidance for practical applications.展开更多
The presence of oxygen functional groups is detrimental to the capacitive performance of porous carbon electrode in organic electrolyte. In this regards, hydrogen thermal reduction has been demonstrated effective appr...The presence of oxygen functional groups is detrimental to the capacitive performance of porous carbon electrode in organic electrolyte. In this regards, hydrogen thermal reduction has been demonstrated effective approach in removing the unstable surface oxygen while maintaining the high porosity of carbon matrix. However, the exact evolution mechanism of various oxygen species during this process, as well as the correlation with electrochemical properties, is still under development. Herein, biomass-based porous carbon is adopted as the model material to trace its structure evolution of oxygen removal under hydrogen thermal reduction process with the temperature range of 400–800 °C. The optimum microstructure with low oxygen content of 0.90% and proper pore size distribution was achieved at 700°C. XPS, TPRMS and Boehm titration results indicate that the oxygen elimination undergoes three distinctive stages(intermolecular dehydration, hydrogenation and decomposition reactions). The optimum microstructure with low oxygen content of 0.90% and proper pore size distribution was achieved at 700 °C. Benefiting from the stable electrochemical interface and the optimized porous structure, the as-obtained HAC-700 exhibit significantly suppressed self-discharge and leak current, with improved cycling stability, which is attributable to the stabilization of electrochemical interface between carbon surface and electrolyte. The result provides insights for rational design of surface chemistry for high-performance carbon electrode towards advanced energy storage.展开更多
The burgeoning global economy during the past decades gives rise to the continuous increase in fossil fuels consumption and rapid growth of CO_(2) emission,which demands an urgent exploration into green and sustainabl...The burgeoning global economy during the past decades gives rise to the continuous increase in fossil fuels consumption and rapid growth of CO_(2) emission,which demands an urgent exploration into green and sustainable devices for energy storage and power management.Supercapacitors based on activated carbon electrodes are promising systems for highly efficient energy harvesting and power supply,but their promotion is hindered by the moderate energy density compared with batteries.Therefore,scalable conversion of CO_(2) into novel carbon nanostructures offers a powerful alternative to tackle both issues:mitigating the greenhouse effect caused by redundant atmospheric CO_(2) and providing carbon materials with enhanced electrochemical performances.In this tutorial review,the techniques,opportunities and barriers in the design and fabrication of advanced carbon materials using CO_(2) as feedstock as well as their impact on the energy-storage performances of supercapacitors are critically examined.In particular,the chemical aspects of various Cv2 conversion reactions are highlighted to establish a detailed understanding for the science and technology involved in the microstructural evolution,surface engineering and porosity control of CO_(2)-converted carbon nanostructures.Finally,the prospects and challenges associated with the industrialization of CO_(2) conversion and their practical application in supercapacitors are also discussed.展开更多
Starch,as a typical polysaccharide with natural spherical morphology,is not only a preferred precursor for preparing carbon materials but also a model polymer for investigating thermochemical evolution mechanisms.Howe...Starch,as a typical polysaccharide with natural spherical morphology,is not only a preferred precursor for preparing carbon materials but also a model polymer for investigating thermochemical evolution mechanisms.However,starch usually suffers from severe foaming and low carbon yield during direct pyrolysis.Herein,we report a simple and eco-friendly dry strategy,by maleic anhydride initiating the esterification of starch,to design carbon microspheres against the starch foaming.Moreover,the infuence of ester grafting on the pyrolytic behavior of starch is also focused.The formation of ester groups in precursor guarantees the structural stability of starch-based intermediate because it can promote the accumulation of unsaturated species and accelerate the water elimination during pyrolysis.Meanwhile,the esterification and dehydration reactions greatly deplete the primary hydroxyl groups in the starch molecules and thus the rapid levoglucosan release is inhibited,which well keeps the spherical morphology of starch and ensures the high carbon yield.In further exploration as anode materials for Lithium-ion batteries,the obtained carbon microspheres exhibit good cyclability and rate performance with a reversible capacity of 444 m Ah g^(-1)at 50 m A g^(-1).This work provides theoretical fundamentals for the controllable thermal transformation of biomass towards wide applications.展开更多
Hard carbons are widely investigated as potential anodes for lithium and sodium ion batteries owing to their internally well-tailored textures(closed pores and defects) and large microcrystalline interlayer spacing. T...Hard carbons are widely investigated as potential anodes for lithium and sodium ion batteries owing to their internally well-tailored textures(closed pores and defects) and large microcrystalline interlayer spacing. The renewable biomass is a green and economically attractive carbon source to produce hard carbons. However, the chemical and structural complexity of biomass has plagued the understanding of evolution mechanism from organic precursors to hard carbons and the structure-property relationship.This makes it difficult to finely tune the microstructure of biomass-derived hard carbons, thus greatly restricting their high-performance applications. Most recently, the optimal utilization and controllable conversion of biomass-derived biopolymers(such as starch, cellulose and lignin) at the molecular level have become a burgeoning area of research to develop hard carbons for advanced batteries.Considering the principal source of carbonaceous materials is from biomass pyrolysis, we firstly overview the chemical structures and pyrolysis behaviors of three main biopolymers. Then, the controllable preparation of hard carbons using various physicochemical properties of biopolymers at the molecular level is systematically discussed. Furthermore, we highlight present challenges and further opportunities in this field. The Review will guide future research works on the design of sustainable hard carbons and the optimization of battery performance.展开更多
The incorporation of boron into carbon material can significantly enhance its capacity performances.However,the origin of the promotion effect of boron doping on electrochemical performances is still unclear,in part d...The incorporation of boron into carbon material can significantly enhance its capacity performances.However,the origin of the promotion effect of boron doping on electrochemical performances is still unclear,in part due to the inadequate exposure of boron configurations resulting from the complexity of traditional carbon materials.To overcome this issue,herein,a series of boron-doped graphene with highly-exposed boron configurations are prepared by tuning annealing temperature.Then the correlation between boron configurations and the electrochemical performances is investigated.The combination of density-functional theory(DFT)computation and NH3-TPD/Py-FTIR indicates that the BCO_(2)configuration formed on the surface of graphene is easier to accept lone-pair electrons than BC_(2)O and BC_(3)configurations due to the stronger Lewis acidity.Such an electronic structure can effectively reduce the number of unstable electron donors and stabilize the electrochemical interface,which is proved by NMR,and critical for improving the electrochemical performances.Further experiments confirm that the optimized BG800 with the largest amount of BCO_(2)configuration presents ultralow leak current,improved cyclic stability,and better rate performance in SBPBF4/PC.This work would provide an insight into the design of high-performance boron-doped carbon materials towards energy storage.展开更多
Closed pores formed in hard carbons play an essential role in sodium storage at plateau region.However,the effect of different structural features on the diffusion of sodium ions into closed pores remains unclear.Here...Closed pores formed in hard carbons play an essential role in sodium storage at plateau region.However,the effect of different structural features on the diffusion of sodium ions into closed pores remains unclear.Herein,a precursor reconstruction strategy is conducted to regulate carbon microstructures including interlayer spacing,defect concentration,and closed pore volume by changing the ratio of aromatic and polysaccharide components.Aromatic structure parts tend to develop disordered carbons with fewer defects,larger interlayer spacing,and smaller closed pore volume,while polysaccharide components prefer to form disordered carbons with more defects,smaller interlayer spacing,and larger closed pore volume.Through the correlation analysis of microstructure features and the sodium storage capacity below 0.1 V.It finds that the intercalation capacity is proportional to the ratio of pseudo-graphitic domains,whereas the pore filling capacity appeared at lower potential gradually decreases with the increasing defect concentration due to homo-ionic repulsion effect,without linear correlation with shortrange microcrystalline and closed pore volume.The optimized sample with suitable interlayer spacing and defect concentration exhibits a high plateau capacity of 241.7 m Ah/g.This work provides insights into the exploitation of closed pore sodium storage performance.展开更多
Compared with conventional graphite anode,hard carbons have the potential to make reversible lithium storage below 0 V accessible due to the formation of dendrites is slow.However,under certain conditions of high curr...Compared with conventional graphite anode,hard carbons have the potential to make reversible lithium storage below 0 V accessible due to the formation of dendrites is slow.However,under certain conditions of high currents and lithiation depths,the irreversible plated lithium occurs and then results in the capacity losses.Herein,we systematically explore the true reversibility of hard carbon anodes below 0 V.We identify the lithiation boundary parameters that control the reversible capacity of hard carbon anodes.When the boundary capacity is controlled below 400 mAh g−1 with current density below 50 mA g−1,no lithium dendrites are observed during the lithiation process.Compared with the discharge cut-off voltage to 0 V,this boundary provides a nearly twice reversible capacity with the capacity retention of 80%after 172 cycles.The results of characterization and finite element model reveal that the large reversible capacity below 0 V of hard carbon anodes is mainly benefited from the dual effect of lithium intercalation and reversible lithium film.After the lithium intercalation,the over-lithiation induces the quick growth of lithium dendrites,worsening the electrochemical irreversibility.This work enables insights of the potentially low-voltage performance of hard carbons in lithium-ion batteries.展开更多
Stable aqueous carbon inks,with graphene sheets(GSs)and carbon black(CB)as conductive fillers,are prepared by a simple one-pot ball-milling method.The asprepared composite ink with 10 wt%GSs shows optimized rheologica...Stable aqueous carbon inks,with graphene sheets(GSs)and carbon black(CB)as conductive fillers,are prepared by a simple one-pot ball-milling method.The asprepared composite ink with 10 wt%GSs shows optimized rheological properties(viscosity and thixotropy)for screen printing.The as-printed coatings based on the above ink are uniform and dense on a polyimide substrate,and exhibit a sandwich-type conductive three dimensional network at the microscale.The resistivity of the typical composite coating is as low as 0.23±0.01Ωcm(92±4Ωsq^-1,25μm),which is 30%as that of a pure CB coating(0.77±0.01Ωcm).It is noteworthy that the resistivity decreases to 0.18±0.01Ωcm(72±4Ωsq^-1,25μm)after a further rolling compression.The coating exhibits good mechanical flexibility,and the resistance slightly increases by 12%after 3000 bending cycles.With the CB/GSs composite coatings as a flexible conductor,fascinating luminescent bookmarks and membrane switches were fabricated,demonstrating the tremendous potential of these coatings in the commercial production of flexible electronics and devices.展开更多
Lithium-(Li-)ion batteries have revolutionized our daily life towards wireless and clean style,and the demand for batteries with higher energy density and better safety is highly required.The next-generation batteries...Lithium-(Li-)ion batteries have revolutionized our daily life towards wireless and clean style,and the demand for batteries with higher energy density and better safety is highly required.The next-generation batteries with innovatory chemistry,material,and engineering breakthroughs are in strong pursuit currently.Herein,the key historical developments of practical electrode materials in Li-ion batteries are summarized as the cornerstone for the innovation of next-generation batteries.In addition,the emerging electrode materials for next-generation batteries are discussed as the revolving challenges and potential strategies.Finally,the future scenario of high-energy-density rechargeable batteries is presented.The combination of theory and experiment under multiscale is highlighted to promote the development of emerging electrode materials.展开更多
In an attempt to overcome the drawbacks of high-capacity layered lithium-rich cathodes xLi2MnO3·(1–x)LiMO2(0<x<1,M=Mn,Ni,and Co),the spinel clothed layered heterostructured materials,x’Li4Mn5O12·(1–...In an attempt to overcome the drawbacks of high-capacity layered lithium-rich cathodes xLi2MnO3·(1–x)LiMO2(0<x<1,M=Mn,Ni,and Co),the spinel clothed layered heterostructured materials,x’Li4Mn5O12·(1–x’)Li[Li0.2Mn0.55Ni0.15Co0.1]O2(x’=0.01,0.03,0.05)have been proposed and synthesized as high-performance cathode materials for high-energy and high-power Li-ion batteries.Based on the characterizations of X-ray diffraction(XRD),transmission electron microscopy(TEM),Raman scattering spectroscopy,it is indicated that ultrathin 3 V spinel Li4Mn5O12 has been successfully clothed on the layered lithium-rich cathode.Electrochemical tests demonstrate the sample 0.01Li4Mn5O12·0.99 Li[Li0.2Mn0.55Ni0.15Co0.1]O2 with an ultrathin clothing layer of spinel phase,exhibits the highest reversible capacity of 289.4 mAh g^(-1) and maintains 259.8 mAh g^(-1) after 80 cycles at 0.1 C rate.Meanwhile,it delivers outstanding rate discharge capacities of 229.4 mAh g^(-1) at 1 C,216.8 mAh g^(-1) at 2 C and 184.4 mAh g^(-1) at 5 C as well as alleviated voltage fade.It is believed the ultrathin clothing spinel layer plays a vital role in the modification of the materials kinetics,and structural and electrochemical stability of the heterostructured cathode.展开更多
A series of water-based conductive carbon pastes were prepared by wet ball milling, followed by vacuum defoaming using isopropyl alcohol, propylene glycol or glycerin as co-solvents. Screen printing was then used to p...A series of water-based conductive carbon pastes were prepared by wet ball milling, followed by vacuum defoaming using isopropyl alcohol, propylene glycol or glycerin as co-solvents. Screen printing was then used to prepare conductive patterns. To determine the influence of co-solvent hydroxyl group number on the properties of water-based conductive carbon pastes, the rheological properties of the pastes and the surface morphologies and conductivities of the printed patterns were characterized. The results show that paste viscosity increased with the number of hydroxyl groups and the latter also affected thixotropy. In addition, the boiling points and surface tensions of the co-solvents increased consistently with hydroxyl group number, affecting the hydrodynamic flow. The conductive carbon paste created using propylene glycol as a co-solvent was the best for screen printing because of its weak coffee-ring effect and appro- priate rheological properties, resulting in a smooth coating surface and uniform deposition of the fillers. The resistivity of the pattern printed using paste PG, containing the closest packing of conductive carbon black particles, was 0.44 Ω cm.展开更多
Redox-active organic electrode materials are highly desirable in realizing next-generation all-in-one bendable electronic systems.Herein,a novel flexible supercapacitors(SCs)electrode is fabricated from poly(anthraqui...Redox-active organic electrode materials are highly desirable in realizing next-generation all-in-one bendable electronic systems.Herein,a novel flexible supercapacitors(SCs)electrode is fabricated from poly(anthraquinonyl sulfide)(PAQS)and single-walled carbon nanotubes(SWCNTs)suspension by a simple vacuum filtration and named as PAQS-SWCNTs.The PAQS-SWCNTs electrode offered an initial capacitance of 223 F·g^-1 and outstanding capacitance retention up to 78.4%after 3×10^4 charge-discharge cycles at 0.5 A·g^-1 current density.In a high potential range(0-3 V)and aprotic electrolyte,the PAQS-SWCNTs electrodes in coin cell exhibited an outstanding energy density of 69 Wh·kg^-1 at a power density of 90.6 W·kg^-1,whereas in the fabricated flexible SCs it retained 63.2 Wh·kg^-1.The PAQS-SWCNTs electrodes also showed extraordinary performance at a higher current density(20 A·g^-1)and maintained a specific capacitance of 55 and 47 F·g^-1 for coin and flexible SCs,respectively.Moreover,the flexible SC is further verified to be able to illuminate up multiple LEDs.These futuristic findings showed that the SCs assembled with flexible PAQS-SWCNTs electrodes have potential application in energy-storage devices and make them highly appealing for future redox supercapacitors.展开更多
基金supported by the National Natural Science Foundation of China (22379157,22179139)the Key Research and Development (R&D) Projects of Shanxi Province(202102040201003)+1 种基金the Research Program of Shanxi Province(202203021211203)the ICC CAS (SCJC-XCL-2023-10 and SCJC-XCL-2023-13)
文摘The chemical activation of various precursors is effective for creating additional closed pores in hard carbons for sodium storage.However,the formation mechanism of closed pores under the influence of pore-forming agents is not well understood.Herein,an effective chemical activation followed by a high-temperature self-healing strategy is employed to generate interconnected closed pores in lignin-derived hard carbon(HCs).By systematic experimental design combined with electron paramagnetic res-onance spectroscopy,it can be found that the content of free radicals in the carbon matrix influences the closure of open pores at high temperatures.Excessively high activation temperature(>700 C)leads to a low free radical concentration,making it difficult to achieve self-healing of open pores at high tempera-tures.By activation at 700°C,a balance between pore making and self-healing is achieved in the final hard carbon.A large number of free radicals triggers rapid growth and aggregation of carbon microcrys-tals,blocking pre-formed open micropores and creating additional interconnected closed pores in as-obtained hard carbons.As a result,the optimized carbon anode(LK-700-1300)delivers a high reversible capacity of 330.8 mA h g^(-1) at 0.03 A g^(-1),which is an increase of 86 mA h g^(-1) compared to the pristine lignin-derived carbon anode(L-700-1300),and exhibits a good rate performance(202.1 mA h g^(-1) at 1 A g^(-1)).This work provides a universal and effective guidance for tuning closed pores of hard carbons from otherprecursors.
基金the National Science Foundation for Excellent Young Scholars of China(21922815)the National Natural Science Foundation of China(22179139)+2 种基金the National Key Research and Development Program of China(2020YFB1505800)the Youth Innovation Promotion Association of CAS(2019178)the“Transformational Technologies for Clean Energy and Demonstration”Strategic Priority Research Program of the CAS(XDA21000000)。
文摘N-doped porous carbon has been extensively investigated for broad electrochemical applications.The performance is significantly impacted by the electrochemical double layer(EDL),which is material dependent and hard to characterize.Limited understanding of doping-derived EDL structure hinders insight into the structure-performance relations and the rational design of high-performance materials.Thus,we analyzed the mass and chemical composition variation of EDL within electrochemical operation by electrochemical quartz crystal microbalance,in-situ X-ray photoelectron spectroscopy,and time-offlight secondary ion mass spectrometry.We found that N-doping triggers specifically adsorbed propylene carbonate solvent in the inner Helmholtz plane(IHP),which prevents ion rearrangement and enhances the migration of cations.However,this specific adsorption accelerated solvent decomposition,rendering rapid performance degradation in practical devices.This work reveals that the surface chemistry of electrodes can cause specific adsorption of solvents and change the EDL structure,which complements the classical EDL theory and provide guidance for practical applications.
基金National Science Foundation for Excellent Young Scholars of China (21922815)Key Research and Development (R&D) Projects of Shanxi Province (201903D121007)+3 种基金Natural Science Foundations of Shanxi Province (201801D221156)DNL Cooperation Fund of CAS (DNL180308)Science and Technology Service Network Initiative of CAS (KFJ-STS-ZDTP-068)Youth Innovation Promotion Association of CAS。
文摘The presence of oxygen functional groups is detrimental to the capacitive performance of porous carbon electrode in organic electrolyte. In this regards, hydrogen thermal reduction has been demonstrated effective approach in removing the unstable surface oxygen while maintaining the high porosity of carbon matrix. However, the exact evolution mechanism of various oxygen species during this process, as well as the correlation with electrochemical properties, is still under development. Herein, biomass-based porous carbon is adopted as the model material to trace its structure evolution of oxygen removal under hydrogen thermal reduction process with the temperature range of 400–800 °C. The optimum microstructure with low oxygen content of 0.90% and proper pore size distribution was achieved at 700°C. XPS, TPRMS and Boehm titration results indicate that the oxygen elimination undergoes three distinctive stages(intermolecular dehydration, hydrogenation and decomposition reactions). The optimum microstructure with low oxygen content of 0.90% and proper pore size distribution was achieved at 700 °C. Benefiting from the stable electrochemical interface and the optimized porous structure, the as-obtained HAC-700 exhibit significantly suppressed self-discharge and leak current, with improved cycling stability, which is attributable to the stabilization of electrochemical interface between carbon surface and electrolyte. The result provides insights for rational design of surface chemistry for high-performance carbon electrode towards advanced energy storage.
基金financially supported by the National Natural Science Foundation of China(No.51907193 and No.51677182)the Dalian National Laboratory(DNL)for Clean Energy Cooperation Fund,CAS(No.DNL201915 and No.DNL201912)+2 种基金the Beijing Municipal Science and Technology Commission(No.Z181100000118006)the Key Research Program of Frontier Sciences,CAS(No.ZDBS-LY-JSC047)the Youth Innovation Promotion Association,CAS(No.2020000022)。
文摘The burgeoning global economy during the past decades gives rise to the continuous increase in fossil fuels consumption and rapid growth of CO_(2) emission,which demands an urgent exploration into green and sustainable devices for energy storage and power management.Supercapacitors based on activated carbon electrodes are promising systems for highly efficient energy harvesting and power supply,but their promotion is hindered by the moderate energy density compared with batteries.Therefore,scalable conversion of CO_(2) into novel carbon nanostructures offers a powerful alternative to tackle both issues:mitigating the greenhouse effect caused by redundant atmospheric CO_(2) and providing carbon materials with enhanced electrochemical performances.In this tutorial review,the techniques,opportunities and barriers in the design and fabrication of advanced carbon materials using CO_(2) as feedstock as well as their impact on the energy-storage performances of supercapacitors are critically examined.In particular,the chemical aspects of various Cv2 conversion reactions are highlighted to establish a detailed understanding for the science and technology involved in the microstructural evolution,surface engineering and porosity control of CO_(2)-converted carbon nanostructures.Finally,the prospects and challenges associated with the industrialization of CO_(2) conversion and their practical application in supercapacitors are also discussed.
基金supported by the National Science Foundation for Excellent Young Scholars of China(21922815)the Key Research and Development(R&D)Projects of Shanxi Province(201903D121180)the National Key Research and Development(R&D)Program of China。
文摘Starch,as a typical polysaccharide with natural spherical morphology,is not only a preferred precursor for preparing carbon materials but also a model polymer for investigating thermochemical evolution mechanisms.However,starch usually suffers from severe foaming and low carbon yield during direct pyrolysis.Herein,we report a simple and eco-friendly dry strategy,by maleic anhydride initiating the esterification of starch,to design carbon microspheres against the starch foaming.Moreover,the infuence of ester grafting on the pyrolytic behavior of starch is also focused.The formation of ester groups in precursor guarantees the structural stability of starch-based intermediate because it can promote the accumulation of unsaturated species and accelerate the water elimination during pyrolysis.Meanwhile,the esterification and dehydration reactions greatly deplete the primary hydroxyl groups in the starch molecules and thus the rapid levoglucosan release is inhibited,which well keeps the spherical morphology of starch and ensures the high carbon yield.In further exploration as anode materials for Lithium-ion batteries,the obtained carbon microspheres exhibit good cyclability and rate performance with a reversible capacity of 444 m Ah g^(-1)at 50 m A g^(-1).This work provides theoretical fundamentals for the controllable thermal transformation of biomass towards wide applications.
基金the support of this work by the Fundamental Research Program of Shanxi Province(20210302123008,20210302124101)the Youth Innovation Promotion Association of CAS(2019178)+1 种基金the National Science Foundation for Excellent Young Scholars of China(21922815)the National Natural Science Foundation of China(21975275,22179139)。
文摘Hard carbons are widely investigated as potential anodes for lithium and sodium ion batteries owing to their internally well-tailored textures(closed pores and defects) and large microcrystalline interlayer spacing. The renewable biomass is a green and economically attractive carbon source to produce hard carbons. However, the chemical and structural complexity of biomass has plagued the understanding of evolution mechanism from organic precursors to hard carbons and the structure-property relationship.This makes it difficult to finely tune the microstructure of biomass-derived hard carbons, thus greatly restricting their high-performance applications. Most recently, the optimal utilization and controllable conversion of biomass-derived biopolymers(such as starch, cellulose and lignin) at the molecular level have become a burgeoning area of research to develop hard carbons for advanced batteries.Considering the principal source of carbonaceous materials is from biomass pyrolysis, we firstly overview the chemical structures and pyrolysis behaviors of three main biopolymers. Then, the controllable preparation of hard carbons using various physicochemical properties of biopolymers at the molecular level is systematically discussed. Furthermore, we highlight present challenges and further opportunities in this field. The Review will guide future research works on the design of sustainable hard carbons and the optimization of battery performance.
基金the National Science Foundation for Excellent Young Scholars of China(21922815)the Key Research and Development(R&D)Projects of Shanxi Province(201903D121007)+3 种基金the Natural Science Foundations of Shanxi Province(201801D221156)the DNL Cooperation Fund of CAS(DNL180308)the Science and Technology Service Network Initiative of CAS(KFJ-STS-ZDTP-068)the Youth Innovation Promotion Association of CAS。
文摘The incorporation of boron into carbon material can significantly enhance its capacity performances.However,the origin of the promotion effect of boron doping on electrochemical performances is still unclear,in part due to the inadequate exposure of boron configurations resulting from the complexity of traditional carbon materials.To overcome this issue,herein,a series of boron-doped graphene with highly-exposed boron configurations are prepared by tuning annealing temperature.Then the correlation between boron configurations and the electrochemical performances is investigated.The combination of density-functional theory(DFT)computation and NH3-TPD/Py-FTIR indicates that the BCO_(2)configuration formed on the surface of graphene is easier to accept lone-pair electrons than BC_(2)O and BC_(3)configurations due to the stronger Lewis acidity.Such an electronic structure can effectively reduce the number of unstable electron donors and stabilize the electrochemical interface,which is proved by NMR,and critical for improving the electrochemical performances.Further experiments confirm that the optimized BG800 with the largest amount of BCO_(2)configuration presents ultralow leak current,improved cyclic stability,and better rate performance in SBPBF4/PC.This work would provide an insight into the design of high-performance boron-doped carbon materials towards energy storage.
基金supported by the National Key Research and Development(R&D)Program of China(No.2020YFB1505803)the Youth Innovation Promotion Association of CAS(No.2019178)the Innovation Fund for Basic Research Program supported by ICC CAS(Nos.SCJC-XCL-2023-10,SCJC-XCL-2023-13)。
文摘Closed pores formed in hard carbons play an essential role in sodium storage at plateau region.However,the effect of different structural features on the diffusion of sodium ions into closed pores remains unclear.Herein,a precursor reconstruction strategy is conducted to regulate carbon microstructures including interlayer spacing,defect concentration,and closed pore volume by changing the ratio of aromatic and polysaccharide components.Aromatic structure parts tend to develop disordered carbons with fewer defects,larger interlayer spacing,and smaller closed pore volume,while polysaccharide components prefer to form disordered carbons with more defects,smaller interlayer spacing,and larger closed pore volume.Through the correlation analysis of microstructure features and the sodium storage capacity below 0.1 V.It finds that the intercalation capacity is proportional to the ratio of pseudo-graphitic domains,whereas the pore filling capacity appeared at lower potential gradually decreases with the increasing defect concentration due to homo-ionic repulsion effect,without linear correlation with shortrange microcrystalline and closed pore volume.The optimized sample with suitable interlayer spacing and defect concentration exhibits a high plateau capacity of 241.7 m Ah/g.This work provides insights into the exploitation of closed pore sodium storage performance.
基金This work gratefully acknowledges the support of National Key Research and Development(R&D)Program of China(grant No.2020YFB1505800)National Science Foundation for Excellent Young Scholars of China(grant No.2192285)+2 种基金the Youth Innovation Promotion Association of CAS(grant No.2019178)Research and Development Project of Key Core and Common Technology of Shanxi Province(grant No.2020xxx014)Key Research and Development(R&D)Projects of Shanxi Province(grant No.202102040201003).
文摘Compared with conventional graphite anode,hard carbons have the potential to make reversible lithium storage below 0 V accessible due to the formation of dendrites is slow.However,under certain conditions of high currents and lithiation depths,the irreversible plated lithium occurs and then results in the capacity losses.Herein,we systematically explore the true reversibility of hard carbon anodes below 0 V.We identify the lithiation boundary parameters that control the reversible capacity of hard carbon anodes.When the boundary capacity is controlled below 400 mAh g−1 with current density below 50 mA g−1,no lithium dendrites are observed during the lithiation process.Compared with the discharge cut-off voltage to 0 V,this boundary provides a nearly twice reversible capacity with the capacity retention of 80%after 172 cycles.The results of characterization and finite element model reveal that the large reversible capacity below 0 V of hard carbon anodes is mainly benefited from the dual effect of lithium intercalation and reversible lithium film.After the lithium intercalation,the over-lithiation induces the quick growth of lithium dendrites,worsening the electrochemical irreversibility.This work enables insights of the potentially low-voltage performance of hard carbons in lithium-ion batteries.
基金supported by the Scientific and Technological Key Project of Shanxi Province (MC2016-04 and MC2016-08)Natural Science Foundation of Shanxi Province (201801D221156)+2 种基金DNL Cooperation Fund of CAS (DNL180308)Science and Technology Service Network Initiative of CAS (KFJ-STS-ZDTP-068)Youth Innovation Promotion Association of CAS
文摘Stable aqueous carbon inks,with graphene sheets(GSs)and carbon black(CB)as conductive fillers,are prepared by a simple one-pot ball-milling method.The asprepared composite ink with 10 wt%GSs shows optimized rheological properties(viscosity and thixotropy)for screen printing.The as-printed coatings based on the above ink are uniform and dense on a polyimide substrate,and exhibit a sandwich-type conductive three dimensional network at the microscale.The resistivity of the typical composite coating is as low as 0.23±0.01Ωcm(92±4Ωsq^-1,25μm),which is 30%as that of a pure CB coating(0.77±0.01Ωcm).It is noteworthy that the resistivity decreases to 0.18±0.01Ωcm(72±4Ωsq^-1,25μm)after a further rolling compression.The coating exhibits good mechanical flexibility,and the resistance slightly increases by 12%after 3000 bending cycles.With the CB/GSs composite coatings as a flexible conductor,fascinating luminescent bookmarks and membrane switches were fabricated,demonstrating the tremendous potential of these coatings in the commercial production of flexible electronics and devices.
基金the National Natural Science Foundation of China(21776019,21825501,and U1801257)Energy Material Advances 11 the National Key Research and Development Program(2016YFA0202500)+3 种基金the Beijing Natural Science Foundation(L182021)the Foundation of National Key Laboratory(6142808190201)the Scientific and Technological Key Project of Shanxi Province(20191102003)the Tsinghua University Initiative Scientific Research Program.References。
文摘Lithium-(Li-)ion batteries have revolutionized our daily life towards wireless and clean style,and the demand for batteries with higher energy density and better safety is highly required.The next-generation batteries with innovatory chemistry,material,and engineering breakthroughs are in strong pursuit currently.Herein,the key historical developments of practical electrode materials in Li-ion batteries are summarized as the cornerstone for the innovation of next-generation batteries.In addition,the emerging electrode materials for next-generation batteries are discussed as the revolving challenges and potential strategies.Finally,the future scenario of high-energy-density rechargeable batteries is presented.The combination of theory and experiment under multiscale is highlighted to promote the development of emerging electrode materials.
基金This work was supported by the National Key R&D Program of China(No.2016YFB0100301)the National Natural Science Foun-dation of China(Nos.21875022,51802020,51802019,U1664255)+1 种基金the Science and Technology Innovation Foundation of Bejjing Institute of Technology Chongqing Innovation Center(No.2020CX5100006)the Young Elite Scientists Sponsorship Program by CAST(No.2018QNRC001).N.L.and L.C.acknowledge the support from Beijing Institute of Technology Research Fund Program for Young Scholars.
文摘In an attempt to overcome the drawbacks of high-capacity layered lithium-rich cathodes xLi2MnO3·(1–x)LiMO2(0<x<1,M=Mn,Ni,and Co),the spinel clothed layered heterostructured materials,x’Li4Mn5O12·(1–x’)Li[Li0.2Mn0.55Ni0.15Co0.1]O2(x’=0.01,0.03,0.05)have been proposed and synthesized as high-performance cathode materials for high-energy and high-power Li-ion batteries.Based on the characterizations of X-ray diffraction(XRD),transmission electron microscopy(TEM),Raman scattering spectroscopy,it is indicated that ultrathin 3 V spinel Li4Mn5O12 has been successfully clothed on the layered lithium-rich cathode.Electrochemical tests demonstrate the sample 0.01Li4Mn5O12·0.99 Li[Li0.2Mn0.55Ni0.15Co0.1]O2 with an ultrathin clothing layer of spinel phase,exhibits the highest reversible capacity of 289.4 mAh g^(-1) and maintains 259.8 mAh g^(-1) after 80 cycles at 0.1 C rate.Meanwhile,it delivers outstanding rate discharge capacities of 229.4 mAh g^(-1) at 1 C,216.8 mAh g^(-1) at 2 C and 184.4 mAh g^(-1) at 5 C as well as alleviated voltage fade.It is believed the ultrathin clothing spinel layer plays a vital role in the modification of the materials kinetics,and structural and electrochemical stability of the heterostructured cathode.
文摘A series of water-based conductive carbon pastes were prepared by wet ball milling, followed by vacuum defoaming using isopropyl alcohol, propylene glycol or glycerin as co-solvents. Screen printing was then used to prepare conductive patterns. To determine the influence of co-solvent hydroxyl group number on the properties of water-based conductive carbon pastes, the rheological properties of the pastes and the surface morphologies and conductivities of the printed patterns were characterized. The results show that paste viscosity increased with the number of hydroxyl groups and the latter also affected thixotropy. In addition, the boiling points and surface tensions of the co-solvents increased consistently with hydroxyl group number, affecting the hydrodynamic flow. The conductive carbon paste created using propylene glycol as a co-solvent was the best for screen printing because of its weak coffee-ring effect and appro- priate rheological properties, resulting in a smooth coating surface and uniform deposition of the fillers. The resistivity of the pattern printed using paste PG, containing the closest packing of conductive carbon black particles, was 0.44 Ω cm.
基金supported by the Ministry of Science and Technology of China(Nos.2016YFF0203803 and 2016YFA020070)the National Natural Science Foundation of China(Nos.51473039 and 21534003)+2 种基金Scientific and Technological Key Project of Shanxi Province(Nos.MC2016-04 and MC2016-08)Natural Science Foundations of Shanxi Province(No.201801D221156)DNL Cooperation Fund of CAS(No.DNL180308)the World Academy of Sciences under the CAS-TWAS PhD President's Fellowship Program.
文摘Redox-active organic electrode materials are highly desirable in realizing next-generation all-in-one bendable electronic systems.Herein,a novel flexible supercapacitors(SCs)electrode is fabricated from poly(anthraquinonyl sulfide)(PAQS)and single-walled carbon nanotubes(SWCNTs)suspension by a simple vacuum filtration and named as PAQS-SWCNTs.The PAQS-SWCNTs electrode offered an initial capacitance of 223 F·g^-1 and outstanding capacitance retention up to 78.4%after 3×10^4 charge-discharge cycles at 0.5 A·g^-1 current density.In a high potential range(0-3 V)and aprotic electrolyte,the PAQS-SWCNTs electrodes in coin cell exhibited an outstanding energy density of 69 Wh·kg^-1 at a power density of 90.6 W·kg^-1,whereas in the fabricated flexible SCs it retained 63.2 Wh·kg^-1.The PAQS-SWCNTs electrodes also showed extraordinary performance at a higher current density(20 A·g^-1)and maintained a specific capacitance of 55 and 47 F·g^-1 for coin and flexible SCs,respectively.Moreover,the flexible SC is further verified to be able to illuminate up multiple LEDs.These futuristic findings showed that the SCs assembled with flexible PAQS-SWCNTs electrodes have potential application in energy-storage devices and make them highly appealing for future redox supercapacitors.
