Layered molybdenum disulfide （MoS2） has received much attention as one of the most promising energy-storage and conversion materials for Li/Na ion batteries. Here, a simple and effective approach is proposed for the...Layered molybdenum disulfide （MoS2） has received much attention as one of the most promising energy-storage and conversion materials for Li/Na ion batteries. Here, a simple and effective approach is proposed for the rational design and preparation of hierarchical three-d imensional （3D） amorphous N-doped carbon nanotube@MoS2 nanosheets （3D-ANCNT@MoS2） via a simple hydrothermal method, followed by an annealing process. With such a unique nanoarchitecture, ultrathin MoS2 nanosheets grown on the external surfaces of polypyrrole-derived ANCNTs are assembled to form a hierarchical 3D nanoarchitecture, where the adopted ANCNTs serve not only as the template and continuous conductive matrix, but can also prevent MoS2 from aggregating and restacking, and help to buffer the volumetric expansion of MoS2 during cycling. More importantly, when evaluated as an anode material for lithium-ion batteries, the 3D-ANCNT@MoS2 composite exhibits excellent cycling stability, superior rate performance, and reversible specific capacity as high as 893.4 mAh·g^-1 at 0.2 A·g^-1 after 200 cycles in a half battery, and 669.4 mAh·g^-1 at 0.2 A·g^-1 after 100 cycles in the 3D-ANCNT@Mo2//LiCoO2 full battery. With respect to sodium-ion batteries, the outstanding reversible capacity, excellent rate behavior, and good cycling performance of 3D-ANCNT@MoS2 composites are also achieved.展开更多
Sodium-ion batteries (SIBs) have been attracting considerable attention as a promising candidate for large-scale energy storage because of the abundance and low-cost of sodium resources. However, lack of appropriate a...Sodium-ion batteries (SIBs) have been attracting considerable attention as a promising candidate for large-scale energy storage because of the abundance and low-cost of sodium resources. However, lack of appropriate anode materials impedes further applications. Herein, a novel self-template strategy is designed to synthesize uniform flowerlike N-doped hierarchical porous carbon networks (NHPCN) with high content of N (15.31 at.%) assembled by ultrathin nanosheets via a self-synthesized single precursor and subsequent thermal annealing. Relying on the synergetic coordination of benzimidazole and 2-methylimidazole with metal ions to produce a flowerlike network, a self-formed single precursor can be harvested. Due to the structural and compositional advantages, including the high N doping, the expanded interlayer spacing, the ultrathin two-dimensional nano-sized subunits, and the three-dimensional porous network structure, these unique NHPCN flowers deliver ultrahigh reversible capacities of 453.7 mAh·g^−1 at 0.1 A·g^−1 and 242.5 mAh·g^−1 at 1 A·g^−1 for 2,500 cycles with exceptional rate capability of 5 A·g^−1 with reversible capacities of 201.2 mAh·g^−1. The greatly improved sodium storage performance of NHPCN confirms the importance of reasonable engineering and synthesis of hierarchical carbon with unique structures.展开更多
MXene is a rising star of two-dimensional(2D)materials for energy relative applications,however,the traditional synthesis of MXene etched by hazard HF acid or LiF+HCl mixed solution is highly dangerous with the risk o...MXene is a rising star of two-dimensional(2D)materials for energy relative applications,however,the traditional synthesis of MXene etched by hazard HF acid or LiF+HCl mixed solution is highly dangerous with the risk of splashing or pouring liquid solutions.In this work,we developed a water-free ionothermal synthesis of 2D Ti3C2 MXene via etching pristine Ti3AlC2 MAX in low-cost choline chloride and oxalic acid based deep eutectic solvents(DES)with the presence of NH4F,thus it was highly safe and convenient to operate solid precursor and product materials at room temperature.Benefited from the low vapor pressure and solvating properties of DES,the prepared Ti3C2(denoted as DES-Ti3C2)possessed a high purity up to 98% compared with 95% for HF etched Ti3C2(denoted as HF-Ti3C2).Notably,an expanded interlayer spacing of 1.35 nm could be achieved due to the intercalation of choline cations in DES-Ti3C2,larger than that of HF-Ti3C2(0.98 nm).As a result,the DES-Ti3C2 anodes exhibited enhanced lithium storage performance,such as high reversible capacity of 208 m Ah g-1at 0.5 A g-1,and long cycle life over 400 times,outperforming most reported pure MXene anodes.The ionothermal synthesis of MXene developed here may pave a new way to safely prepare other MXene for various energy relating applications.展开更多
Carbonaceous materials have been regarded as highly promising anode candidates for potassium storage with their cost-effectiveness and environmental benignity.However,low specific capacity and difficulty in large-scal...Carbonaceous materials have been regarded as highly promising anode candidates for potassium storage with their cost-effectiveness and environmental benignity.However,low specific capacity and difficulty in large-scale synthesis largely hinder their further development.Herein,a thermal-induced potassium–carbon alloy phase(K_(x)C_(y))with the expanded interlayer spacing strategy is first put forward.Through in situ high-temperature X-ray diffraction,a K_(2)C_(2) phase is evoked by thermal energy during the in-situ carbonization process of carbon quantum dots intermediate derived from potassium-containing precursors,whereas no lithium or sodium–carbon alloy phase is observed from lithium/sodium-containing precursors.The asobtained ultra-thin carbon nanosheets achieve adjustable layer spacing,preparation in bulk,delivering reversible potassium storage of 403.4 mAh g^(−1) at 100 mA g^(−1) and 161.2 mAh g^(−1) even at 5.0 A g^(−1),which is one of the most impressive K-storage performances reported so far with great potential application.Furthermore,the assembled potassium-ion hybrid capacitor by combining the impressive CFMs-900 anode with the three-dimensional framework-activated carbon delivers a high energy-power density of 251.7 Wh kg^(−1) at 250Wkg^(−1) with long-term stability.This study opens a scalable avenue to realize the expanded interlayer spacing,which can be extended to other multicarboxyl potassium salts and can provide approach for the design of high-performance carbon anode materials for potassium storage.展开更多
Two-dimensional(2D)MoS_(2) nanomaterials have been extensively studied due to their special structure and high theoretical capacity,but it is still a huge challenge to improve its cycle stability and achieve superior ...Two-dimensional(2D)MoS_(2) nanomaterials have been extensively studied due to their special structure and high theoretical capacity,but it is still a huge challenge to improve its cycle stability and achieve superior fast charge and discharge performance.Herein,a facile one-step hydrothermal method is proposed to synthetize an ordered and self-assembled MoS_(2) nanoflower(MoS_(2)/C NF)with expanded interlayer spacing via embedding a carbon layer into the interlayer.The carbon layer in the MoS_(2) interlayer can speed the transfer of electrons,while the nanoflower structure promotes the ions transport and improves the structural stability during the charging/discharging process.Therefore,MoS_(2)/C NF electrode exhibits exceptional rate performance(318.2 and 302.3 mA·h·g^(-1) at 5.0 and 10.0 A·g^(-1),respectively)and extraordinary cycle durability(98.8%retention after 300 cycles at a current density of 1.0 A·g^(-1)).This work provides a simple and feasible method for constructing high-performance anode composites for sodium ion batteries with excellent cycle durability and fast charge/discharge ability.展开更多
As an alternative for lithium-ion batteries(LIBs),sodium-ion batteries(SIBs)have lately received tremendous interest due to their abundant reserves as well as low cost.Nevertheless,the lack of suitable anode materials...As an alternative for lithium-ion batteries(LIBs),sodium-ion batteries(SIBs)have lately received tremendous interest due to their abundant reserves as well as low cost.Nevertheless,the lack of suitable anode materials severely hinders the application of sodium-ion batteries.TiS_(2)is elected as a representative material owing to its unique layered structure.But it always suffers from capacity fade due to poor electrochemical kinetics and structural stability.In this work,we fabricate a pre-potassiated TiS_(2)as a host material for sodium storage by an electrochemical pre-potassiation strategy.The intercalation/extraction mechanism,structural changes and reaction kinetics are completely investigated to reveal the outstanding electrochemical property of pre-potassiated TiS_(2)electrode.It turns out that the large interlayer space of pre-potassiated TiS_(2)is conducive to the diffusion of sodium ions,inducing the reduction of entropic barrier for the electrochemical reactions.In addition,the pre-potassiated host structure is still firmly maintained upon repeated cycles.Therefore,the pre-potassiated TiS_(2)presents superior rate capability(165.9 mA h g^(−1) at 1 C and 132.1 mA h g^(−1) at 20 C)and long-term cycling stability(85.3%capacity retention at 5 C after 500 cycles)for SIBs.This research provides an avenue to construct long-life sodium energy storage systems based on pre-potassiated TiS_(2).展开更多
Layered structure MoS_(2) nanosheets have shown great potential for energy storage applications.However,the methodology for elaborately controllable growth of MoS_(2) onto carbonaceous matrix for promoting the electro...Layered structure MoS_(2) nanosheets have shown great potential for energy storage applications.However,the methodology for elaborately controllable growth of MoS_(2) onto carbonaceous matrix for promoting the electrochemical performance is highly desirable.Herein,a high-effective,all-in-one in-situ conversion growth strategy has been proposed to construct a stable sandwich-type nanostructure.The formation of the optimized C-MoS_(2)/NCNTs product undergoes a dissolution-recrystallization process,in which ultra-thin carbon layer-coated MoS_(2) nanosheets densely assembled onto the surface of polyimide(PI)derived N-doped carbon nanotubes(CNTs).Theoretical simulation reveals that MoS_(2) nanosheets possessing an expanded interlayer spacing of 0.92 nm can greatly reduce the barrier energy of Na ions mitigation.Ac-cordingly,the as-made C-MoS_(2)/NCNTs anode delivers superior cycling stability(82%capacity retention after 400 cycles at 1 A g^(−1))and rate performance(348 mAh g^(−1) at 2 A g^(−1)).The results demonstrate that the expanded MoS_(2) interlayer distance,ultrathin outer carbon coating,and N-doped CNTs matrix together accounts for the outstanding sodium storage capability for the C-MoS_(2)/NCNTs electrode.展开更多
MXenes obtained significant attention in the field of energy storage devices due to their characteristic layered structure,modifiable surface functional groups,large electrochemically active surface,and regulable inte...MXenes obtained significant attention in the field of energy storage devices due to their characteristic layered structure,modifiable surface functional groups,large electrochemically active surface,and regulable interlayer spacing.Nonetheless,the self-restacking and sluggish ions diffusion kinetics performance of MXenes during the alkali metal ions insertion/extraction process severely impedes their cycle stability and rate capability.This paper proposes an aniline molecule welding strategy for welding p-phenylenediamine(PPDA)into the interlayers of Ti_(2)C through a dehydration condensation reaction.The welded PPDA molecules can contribute pillar effect to the layered structure of Ti_(2)C.The pillar effect effectively maintains the structural stability during the sodium ions insertion/extraction process and effectively expands the interlayer spacing of Ti_(2)C from 1.16 to 1.38 nm,thereby enhancing ions diffusion kinetics performance and improving the long-term cycle stability.The Ti_(2)C-PPDA demonstrates outstanding Na+storage capability,exhibiting a specific capacity of 100.2 mAh·g^(-1)at a current density of 0.1 A·g^(-1)over 960 cycles and delivering a remarkable rate capability 81.2 mAh·g^(-1)at a current density of 5 A·g^(-1).The study demonstrates that expanding interlayer spacing is a promising strategy to enhance the Na+storage capacity and improve long-term cycling stability,which provides significant guidance for the design of two-dimensional Na+storage materials with high-rate capability and cycle stability.展开更多
VS2 with natural layered structure and metallic conductivity is a prospective candidate for sodium-ion batteries(SIBs)and potassium-ion batteries(PIBs).However,due to large radius of Na+and K+,the limited interlayer s...VS2 with natural layered structure and metallic conductivity is a prospective candidate for sodium-ion batteries(SIBs)and potassium-ion batteries(PIBs).However,due to large radius of Na+and K+,the limited interlayer spacing(0.57 nm)of VS2 generally determines high ion diffusion barrier and large volume variation,resulting in unsatisfactory electrochemical performance of SIBs and PIBs.In this work,flower-like VS_(2)/N-doped carbon(VS_(2)/N-C)with expanded(001)plane is grown on reduced graphene oxide(rGO)via a solvothermal and subsequently carbonization strategy.In the VS_(2)/N-C@rGO nanohybrids,the ultrathin VS2"petals"are alternately intercalated by the N-doped porous carbon monolayers to achieve an expanded interlayer spacing(1.02 nm),which can effectively reduce ions diffusion barrier,expose abundant active sites for Na+/K+intercalation,and tolerate large volume variation.The N-C and rGO carbonous materials can significantly promote the electrical conductivity and structural stability.Benefited from the synergistic effect,the VS2/N-C@rGO electrode exhibits large reversible capacity(Na+:407 mAh·g^(-1) at 1 A·g^(-1);K^(+):334 mAh·g^(-1) at 0.2 A·g^(-1)),high rate capacity(Na+:273 mAh·g^(-1) at 8 A·g^(-1);K+:186 mAh·g^(-1) at 5 A·g^(-1)),and remarkable cycling stability(Na+:316 mAh·g^(-1) at 2 A·g^(-1) after 1,400 cycles;K^(+):216 mAh·g^(-1) at 1 A·g^(-1) after 500 cycles).展开更多
MoS2 is considered as an ideal electrode material in the field of energy storage due to high theoretical specific capacity and unique layered structure.However,limited interlayer distance and poor intrinsic electrical...MoS2 is considered as an ideal electrode material in the field of energy storage due to high theoretical specific capacity and unique layered structure.However,limited interlayer distance and poor intrinsic electrical conductivity restrict its potential realworld application.Herein,an alternately intercalated structure of MoS2 monolayer and N-doped porous carbon(NC)layer is grown on reduced graphene oxide(rGO)via a chemical intercalated strategy.The expanded interlayer distance of MoS2(0.96 nm),enlarged by the intercalation of N-doped porous carbon layers,can enhance ion diffusion mobility,provide additional reactive sites for ion storage and maintain the stability of electrode structure.In addition,the hierarchical structures between rGO substrate and intercalated N-doped carbon layers construct a three-dimensional(3D)conductive network,which can significantly improve the electrical conductivity and the structural stability.As a result,the rGO-supported MoS2/NC electrode exhibits an ultrahigh reversible capacity and remarkable long cycling stability for sodium-ion batteries(SIBs)and potassium-ion(PIBs).Meanwhile,the as-obtained MoS2/NC@rGO electrode also delivers a superior cycle performance of 250 mAh·g−1 after 160 cycles at 0.5 A·g−1 when employed as an anode for sodium-ion full cells.展开更多
基金This work was supported by the National Natural Science Foundation of China （No. 51672213） and the Natural Science Foundation of Shaanxi Province （Nos. 2017ZDCXL-GY-08-01 and 2017JM2025）.
文摘Layered molybdenum disulfide （MoS2） has received much attention as one of the most promising energy-storage and conversion materials for Li/Na ion batteries. Here, a simple and effective approach is proposed for the rational design and preparation of hierarchical three-d imensional （3D） amorphous N-doped carbon nanotube@MoS2 nanosheets （3D-ANCNT@MoS2） via a simple hydrothermal method, followed by an annealing process. With such a unique nanoarchitecture, ultrathin MoS2 nanosheets grown on the external surfaces of polypyrrole-derived ANCNTs are assembled to form a hierarchical 3D nanoarchitecture, where the adopted ANCNTs serve not only as the template and continuous conductive matrix, but can also prevent MoS2 from aggregating and restacking, and help to buffer the volumetric expansion of MoS2 during cycling. More importantly, when evaluated as an anode material for lithium-ion batteries, the 3D-ANCNT@MoS2 composite exhibits excellent cycling stability, superior rate performance, and reversible specific capacity as high as 893.4 mAh·g^-1 at 0.2 A·g^-1 after 200 cycles in a half battery, and 669.4 mAh·g^-1 at 0.2 A·g^-1 after 100 cycles in the 3D-ANCNT@Mo2//LiCoO2 full battery. With respect to sodium-ion batteries, the outstanding reversible capacity, excellent rate behavior, and good cycling performance of 3D-ANCNT@MoS2 composites are also achieved.
基金The work was financially supported by the National Natural Science of Foundation of China(No.51672114)the Natural Science Foundation of Jiangsu Province(No.BK20181469)the Zhenjiang Key Research and Development Project(Social Development)(No.SSH20190140049).
文摘Sodium-ion batteries (SIBs) have been attracting considerable attention as a promising candidate for large-scale energy storage because of the abundance and low-cost of sodium resources. However, lack of appropriate anode materials impedes further applications. Herein, a novel self-template strategy is designed to synthesize uniform flowerlike N-doped hierarchical porous carbon networks (NHPCN) with high content of N (15.31 at.%) assembled by ultrathin nanosheets via a self-synthesized single precursor and subsequent thermal annealing. Relying on the synergetic coordination of benzimidazole and 2-methylimidazole with metal ions to produce a flowerlike network, a self-formed single precursor can be harvested. Due to the structural and compositional advantages, including the high N doping, the expanded interlayer spacing, the ultrathin two-dimensional nano-sized subunits, and the three-dimensional porous network structure, these unique NHPCN flowers deliver ultrahigh reversible capacities of 453.7 mAh·g^−1 at 0.1 A·g^−1 and 242.5 mAh·g^−1 at 1 A·g^−1 for 2,500 cycles with exceptional rate capability of 5 A·g^−1 with reversible capacities of 201.2 mAh·g^−1. The greatly improved sodium storage performance of NHPCN confirms the importance of reasonable engineering and synthesis of hierarchical carbon with unique structures.
基金financially supported by the National Natural Science Foundation of China (Nos.21601029, 21601030)the Open Project Program of the State Key Laboratory of Inorganic Synthesis and Preparative Chemistry (Nos.2017-33, 2017-26)the Fundamental Research Funds for the Central Universities of China (No.N180503012)。
文摘MXene is a rising star of two-dimensional(2D)materials for energy relative applications,however,the traditional synthesis of MXene etched by hazard HF acid or LiF+HCl mixed solution is highly dangerous with the risk of splashing or pouring liquid solutions.In this work,we developed a water-free ionothermal synthesis of 2D Ti3C2 MXene via etching pristine Ti3AlC2 MAX in low-cost choline chloride and oxalic acid based deep eutectic solvents(DES)with the presence of NH4F,thus it was highly safe and convenient to operate solid precursor and product materials at room temperature.Benefited from the low vapor pressure and solvating properties of DES,the prepared Ti3C2(denoted as DES-Ti3C2)possessed a high purity up to 98% compared with 95% for HF etched Ti3C2(denoted as HF-Ti3C2).Notably,an expanded interlayer spacing of 1.35 nm could be achieved due to the intercalation of choline cations in DES-Ti3C2,larger than that of HF-Ti3C2(0.98 nm).As a result,the DES-Ti3C2 anodes exhibited enhanced lithium storage performance,such as high reversible capacity of 208 m Ah g-1at 0.5 A g-1,and long cycle life over 400 times,outperforming most reported pure MXene anodes.The ionothermal synthesis of MXene developed here may pave a new way to safely prepare other MXene for various energy relating applications.
基金National Natural Science Foundation of China,Grant/Award Numbers:52004338,51904342,52074359Guangdong Provincial Department of Natural Resources,Grant/Award Number:2020-011Hunan Provincial Natural Science Foundation,Grant/Award Number:2020JJ5696。
文摘Carbonaceous materials have been regarded as highly promising anode candidates for potassium storage with their cost-effectiveness and environmental benignity.However,low specific capacity and difficulty in large-scale synthesis largely hinder their further development.Herein,a thermal-induced potassium–carbon alloy phase(K_(x)C_(y))with the expanded interlayer spacing strategy is first put forward.Through in situ high-temperature X-ray diffraction,a K_(2)C_(2) phase is evoked by thermal energy during the in-situ carbonization process of carbon quantum dots intermediate derived from potassium-containing precursors,whereas no lithium or sodium–carbon alloy phase is observed from lithium/sodium-containing precursors.The asobtained ultra-thin carbon nanosheets achieve adjustable layer spacing,preparation in bulk,delivering reversible potassium storage of 403.4 mAh g^(−1) at 100 mA g^(−1) and 161.2 mAh g^(−1) even at 5.0 A g^(−1),which is one of the most impressive K-storage performances reported so far with great potential application.Furthermore,the assembled potassium-ion hybrid capacitor by combining the impressive CFMs-900 anode with the three-dimensional framework-activated carbon delivers a high energy-power density of 251.7 Wh kg^(−1) at 250Wkg^(−1) with long-term stability.This study opens a scalable avenue to realize the expanded interlayer spacing,which can be extended to other multicarboxyl potassium salts and can provide approach for the design of high-performance carbon anode materials for potassium storage.
基金National Natural Science Foundation of China(51874142)Pearl River S&T Nova Program of Guangzhou(201806010031)+3 种基金the Fundamental Research Funds for the Central Universities(2019JQ09)Guangdong Innovative and Entrepreneurial Research Team Program(2016ZT06N569)Tip-top Scientific and Technical Innovative Youth Talents of Guangdong Special Support Program(2019TQ05L903)Young Elite Scientists Sponsorship Program by CAST(2019QNRC001).
文摘Two-dimensional(2D)MoS_(2) nanomaterials have been extensively studied due to their special structure and high theoretical capacity,but it is still a huge challenge to improve its cycle stability and achieve superior fast charge and discharge performance.Herein,a facile one-step hydrothermal method is proposed to synthetize an ordered and self-assembled MoS_(2) nanoflower(MoS_(2)/C NF)with expanded interlayer spacing via embedding a carbon layer into the interlayer.The carbon layer in the MoS_(2) interlayer can speed the transfer of electrons,while the nanoflower structure promotes the ions transport and improves the structural stability during the charging/discharging process.Therefore,MoS_(2)/C NF electrode exhibits exceptional rate performance(318.2 and 302.3 mA·h·g^(-1) at 5.0 and 10.0 A·g^(-1),respectively)and extraordinary cycle durability(98.8%retention after 300 cycles at a current density of 1.0 A·g^(-1)).This work provides a simple and feasible method for constructing high-performance anode composites for sodium ion batteries with excellent cycle durability and fast charge/discharge ability.
基金sponsored by NSAF joint Fund(U1830106)Science and Technology Innovation 2025 Major Program of Ningbo(2018B10061)+1 种基金National Natural Science Foundation of China(U1632114,51901205)K.C.Wong Magna Fund in Ningbo University。
文摘As an alternative for lithium-ion batteries(LIBs),sodium-ion batteries(SIBs)have lately received tremendous interest due to their abundant reserves as well as low cost.Nevertheless,the lack of suitable anode materials severely hinders the application of sodium-ion batteries.TiS_(2)is elected as a representative material owing to its unique layered structure.But it always suffers from capacity fade due to poor electrochemical kinetics and structural stability.In this work,we fabricate a pre-potassiated TiS_(2)as a host material for sodium storage by an electrochemical pre-potassiation strategy.The intercalation/extraction mechanism,structural changes and reaction kinetics are completely investigated to reveal the outstanding electrochemical property of pre-potassiated TiS_(2)electrode.It turns out that the large interlayer space of pre-potassiated TiS_(2)is conducive to the diffusion of sodium ions,inducing the reduction of entropic barrier for the electrochemical reactions.In addition,the pre-potassiated host structure is still firmly maintained upon repeated cycles.Therefore,the pre-potassiated TiS_(2)presents superior rate capability(165.9 mA h g^(−1) at 1 C and 132.1 mA h g^(−1) at 20 C)and long-term cycling stability(85.3%capacity retention at 5 C after 500 cycles)for SIBs.This research provides an avenue to construct long-life sodium energy storage systems based on pre-potassiated TiS_(2).
基金financially supported by the Shuguang Program from Shanghai Education Development Foundation and Shanghai Municipal Education Commission (18SG035)State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, Donghua University (KF2015)。
文摘Layered structure MoS_(2) nanosheets have shown great potential for energy storage applications.However,the methodology for elaborately controllable growth of MoS_(2) onto carbonaceous matrix for promoting the electrochemical performance is highly desirable.Herein,a high-effective,all-in-one in-situ conversion growth strategy has been proposed to construct a stable sandwich-type nanostructure.The formation of the optimized C-MoS_(2)/NCNTs product undergoes a dissolution-recrystallization process,in which ultra-thin carbon layer-coated MoS_(2) nanosheets densely assembled onto the surface of polyimide(PI)derived N-doped carbon nanotubes(CNTs).Theoretical simulation reveals that MoS_(2) nanosheets possessing an expanded interlayer spacing of 0.92 nm can greatly reduce the barrier energy of Na ions mitigation.Ac-cordingly,the as-made C-MoS_(2)/NCNTs anode delivers superior cycling stability(82%capacity retention after 400 cycles at 1 A g^(−1))and rate performance(348 mAh g^(−1) at 2 A g^(−1)).The results demonstrate that the expanded MoS_(2) interlayer distance,ultrathin outer carbon coating,and N-doped CNTs matrix together accounts for the outstanding sodium storage capability for the C-MoS_(2)/NCNTs electrode.
基金supported by the National Natural Science Foundation of China(No.52062030)the Key Program of the Natural Science Foundation of Gansu Province(23JRRA789)。
文摘MXenes obtained significant attention in the field of energy storage devices due to their characteristic layered structure,modifiable surface functional groups,large electrochemically active surface,and regulable interlayer spacing.Nonetheless,the self-restacking and sluggish ions diffusion kinetics performance of MXenes during the alkali metal ions insertion/extraction process severely impedes their cycle stability and rate capability.This paper proposes an aniline molecule welding strategy for welding p-phenylenediamine(PPDA)into the interlayers of Ti_(2)C through a dehydration condensation reaction.The welded PPDA molecules can contribute pillar effect to the layered structure of Ti_(2)C.The pillar effect effectively maintains the structural stability during the sodium ions insertion/extraction process and effectively expands the interlayer spacing of Ti_(2)C from 1.16 to 1.38 nm,thereby enhancing ions diffusion kinetics performance and improving the long-term cycle stability.The Ti_(2)C-PPDA demonstrates outstanding Na+storage capability,exhibiting a specific capacity of 100.2 mAh·g^(-1)at a current density of 0.1 A·g^(-1)over 960 cycles and delivering a remarkable rate capability 81.2 mAh·g^(-1)at a current density of 5 A·g^(-1).The study demonstrates that expanding interlayer spacing is a promising strategy to enhance the Na+storage capacity and improve long-term cycling stability,which provides significant guidance for the design of two-dimensional Na+storage materials with high-rate capability and cycle stability.
基金The authors are grateful to the National Key Research and Development Project(No.51890863)the National Natural Science Foundation of China(NSFC,Nos.51872172 and 51972197)+2 种基金the Natural Science Foundation of Shandong Province(Nos.ZR2018MEM010 and ZR2019MEM021)Major Research and Development Program for Public Welfare in Shandong(No.2018GGX102021)Young Scholars Program of Shandong University.
文摘VS2 with natural layered structure and metallic conductivity is a prospective candidate for sodium-ion batteries(SIBs)and potassium-ion batteries(PIBs).However,due to large radius of Na+and K+,the limited interlayer spacing(0.57 nm)of VS2 generally determines high ion diffusion barrier and large volume variation,resulting in unsatisfactory electrochemical performance of SIBs and PIBs.In this work,flower-like VS_(2)/N-doped carbon(VS_(2)/N-C)with expanded(001)plane is grown on reduced graphene oxide(rGO)via a solvothermal and subsequently carbonization strategy.In the VS_(2)/N-C@rGO nanohybrids,the ultrathin VS2"petals"are alternately intercalated by the N-doped porous carbon monolayers to achieve an expanded interlayer spacing(1.02 nm),which can effectively reduce ions diffusion barrier,expose abundant active sites for Na+/K+intercalation,and tolerate large volume variation.The N-C and rGO carbonous materials can significantly promote the electrical conductivity and structural stability.Benefited from the synergistic effect,the VS2/N-C@rGO electrode exhibits large reversible capacity(Na+:407 mAh·g^(-1) at 1 A·g^(-1);K^(+):334 mAh·g^(-1) at 0.2 A·g^(-1)),high rate capacity(Na+:273 mAh·g^(-1) at 8 A·g^(-1);K+:186 mAh·g^(-1) at 5 A·g^(-1)),and remarkable cycling stability(Na+:316 mAh·g^(-1) at 2 A·g^(-1) after 1,400 cycles;K^(+):216 mAh·g^(-1) at 1 A·g^(-1) after 500 cycles).
基金The authors are grateful to the National Key Research and Development Project(No.51890863)the National Natural Science Foundation of China(Nos.51872172 and 51972197)+1 种基金Natural Science Foundation of Shandong Province(Nos.ZR2019MEM021 and ZR2020QE067)Young Scholars Program of Shandong University.
文摘MoS2 is considered as an ideal electrode material in the field of energy storage due to high theoretical specific capacity and unique layered structure.However,limited interlayer distance and poor intrinsic electrical conductivity restrict its potential realworld application.Herein,an alternately intercalated structure of MoS2 monolayer and N-doped porous carbon(NC)layer is grown on reduced graphene oxide(rGO)via a chemical intercalated strategy.The expanded interlayer distance of MoS2(0.96 nm),enlarged by the intercalation of N-doped porous carbon layers,can enhance ion diffusion mobility,provide additional reactive sites for ion storage and maintain the stability of electrode structure.In addition,the hierarchical structures between rGO substrate and intercalated N-doped carbon layers construct a three-dimensional(3D)conductive network,which can significantly improve the electrical conductivity and the structural stability.As a result,the rGO-supported MoS2/NC electrode exhibits an ultrahigh reversible capacity and remarkable long cycling stability for sodium-ion batteries(SIBs)and potassium-ion(PIBs).Meanwhile,the as-obtained MoS2/NC@rGO electrode also delivers a superior cycle performance of 250 mAh·g−1 after 160 cycles at 0.5 A·g−1 when employed as an anode for sodium-ion full cells.
