钠离子电池(SIBs)的阳极材料一直备受研究关注,但缓慢的动力学行为和较大的体积变化限制了其在实际应用中的推广。为了克服这些问题,本研究利用金属有机框架和MoS_(2)的优异性能,设计并制备了具有稳定骨架结构的复合材料。以Co-ZIF为前...钠离子电池(SIBs)的阳极材料一直备受研究关注,但缓慢的动力学行为和较大的体积变化限制了其在实际应用中的推广。为了克服这些问题,本研究利用金属有机框架和MoS_(2)的优异性能,设计并制备了具有稳定骨架结构的复合材料。以Co-ZIF为前驱体,添加Mo源材料,在高温硫化烧结的过程中,构建了花状的Co_(9)S_(8)/MoS_(2)/C复合材料,探究其在不同温度条件下的结构和电化学性能。此外,通过密度泛函理论(DFT)分析了Co9S8(001)/MoS2异质结对扩散动力学的影响。结果表明,电子结构在异质结构的界面处发生了重塑,Co_(9)S_(8)/MoS_(2)表现出典型的金属性和显著增强的电子导电性。在所有样品中,700℃合成的阳极材料Co_(9)S_(8)/MoS_(2)/C具有更稳定的结构和优异的电化学性能。当电流密度从4000恢复到40 mA g^(-1)时,Co_(9)S_(8)/MoS_(2)/C-700的放电容量可以从368 mAh g^(-1)完全恢复到571 mAh g^(-1),并稳定在543 mAh g^(-1)。综上所述,本研究提供了一些关于异质结材料合理制备的思路,有助于设计高性能的金属钠离子电池负极复合材料。展开更多
以四水合钼酸铵、六水合硝酸钴和硫脲为原料,采用一步水热法在钛网(TM)上原位构筑了不同阵列结构Co_(9)S_(8)/MoS_(2)@TM催化电极。通过改变原料中钴、钼、硫的物质的量之比来调控Co_(9)S_(8)/MoS_(2)@TM电极的结构。采用SEM、XRD和XPS...以四水合钼酸铵、六水合硝酸钴和硫脲为原料,采用一步水热法在钛网(TM)上原位构筑了不同阵列结构Co_(9)S_(8)/MoS_(2)@TM催化电极。通过改变原料中钴、钼、硫的物质的量之比来调控Co_(9)S_(8)/MoS_(2)@TM电极的结构。采用SEM、XRD和XPS对Co_(9)S_(8)/MoS_(2)@TM进行物相分析和形貌表征,并在1 mol/L KOH电解液中对Co_(9)S_(8)/MoS_(2)@TM的电催化析氧性能进行了研究。结果表明,钴、钼、硫的物质的量之比为10∶14∶600时,制备的Co_(9)S_(8)/MoS_(2)@TM为3D花瓣状阵列结构,且在10 m A/cm^(2)电流密度下过电势为271 m V,塔菲尔斜率为88.5 m V/dec,具有良好的析氧稳定性和耐久性,展现了优异的电化学性能。展开更多
Transition metal sulfides(TMSs)have been regarded as greatly promising electrode materials for supercapacitors because of abundant redox electroactive sites and outstanding conductivity.Herein,we report a self-support...Transition metal sulfides(TMSs)have been regarded as greatly promising electrode materials for supercapacitors because of abundant redox electroactive sites and outstanding conductivity.Herein,we report a self-supported hierarchical Mn doped Co_(9)S_(8)@Co(OH)_(2) nanosheet arrays on nickel foam(NF)substrate by a one-step metal–organic-framework(MOF)engaged approach and a subsequent sulfurization process.Experimental results reveal that the introduction of manganese endows improved electric conductivity,enlarged electrochemical specific surface area,adjusted electronic structure of Co_(9)S_(8)@Co(OH)_(2) and enhanced interfacial activities as well as facilitated reaction kinetics of electrodes.The optimal Mn doped Co_(9)S_(8)@Co(OH)_(2) electrode exhibits an ultrahigh specific capacitance of 3745 F g^(-1) at 1 A g^(-1)(5.618 F cm^(-2) at 1.5 mA cm^(-2))and sustains 1710 F g^(-1) at 30 A g^(-1)(2.565 F cm^(-2) at 45 mA cm^(-2)),surpassing most reported values on TMSs.Moreover,a battery-type asymmetric supercapacitor(ASC)device is constructed,which delivers high energy density of 50.2 Wh kg^(-1) at power density of 800 W kg^(-1),and outstanding long-term cycling stability(94%capacitance retention after 8000 cycles).The encouraging results might offer an effective strategy to optimize the TMSs for energy-storage devices.展开更多
Designing and fabricating of heterostructured materials with long-term cycling stability and high-rate capacity for the anode of sodium-ion batteries(SIBs)still remain a great challenge.Herein,micro-flower-like MoS_(2...Designing and fabricating of heterostructured materials with long-term cycling stability and high-rate capacity for the anode of sodium-ion batteries(SIBs)still remain a great challenge.Herein,micro-flower-like MoS_(2)-modified Co_(9)S_(8)(Co_(9)S_(8)/MoS_(2))with a three-dimensional(3D)heterostructure was first obtained via a simple solvothermal synthesis followed by a solid sulfidation treatment process.As a material for the anode of SIBs,the Co_(9)S_(8)/MoS_(2)-based electrode with an initial Co/Mo molar ratio of 1/1(denoted as CM55-S)exhibits the best sodium storage performance with a boosted capacity,superior reversibility(424.5 mAh g^(-1)@2 A g^(-1)at the 1600th cycle,401.1 mAh g^(-1)@5 A g^(-1)at the 800th cycle),and an excellent rate capacity(210.1 mAh g^(-1)@20 A g^(-1)).Density functional theory(DFT)calculations confirm that the Co_(9)S_(8)/MoS_(2)heterostructure has a lower energy barrier(0.30 eV)than the pure Co_(9)S_(8)(0.53 eV).It is expected that such a heterostructured material could be an attractive candidate as the material of the anode for SIBs.展开更多
Rational structure design and regulation are of paramount importance for obtaining electrode materials with desirable electrochemical performance.Here,a novel binder-free electrode with the hollow Co_(9)S_(8) core@mul...Rational structure design and regulation are of paramount importance for obtaining electrode materials with desirable electrochemical performance.Here,a novel binder-free electrode with the hollow Co_(9)S_(8) core@multi-shell structure(CS-x@MXene@Bi_(2)O_(3))derived from metal-organic frameworks(MOFs)precursor is well designed by the electrospinning,sulfuration,carbonization,and hydrothermal processes.In this architecture,the concentration of Co_(9)S_(8)(CS-x)is optimized for an ideal flexible substrate,which alleviates the dimensional variation for long cycle life.The unique cores and the MXene flakes engineered by Bi_(2)O_(3) multiple shells can be responsible for the superior characteristics,including a fast electronic pathway,large specific surface area,enhanced electrical conductivity,and improved electrochemical performance.As expected,the obtained CS-2@MXene@Bi_(2)O_(3) binder-free electrode exhibits a high discharge capacitance of 646.1 F g^(–1)(1 A g^(–1)).Two binder-free electrodes can be assembled into a solid-state supercapacitor with desirable energy and power density,and long-term cyclic stability is demonstrated through 5000 cycles.Given these advantages,the CS-2@MXene@Bi_(2)O_(3) is selected as the electrode in a foldable supercapacitor.More importantly,the specific capacitance is reserved after various deformations.Therefore,it is expected that binder-free electrode materials with the unique core@shell structure design could be applied in wearable and portable energy conversion devices.展开更多
文摘钠离子电池(SIBs)的阳极材料一直备受研究关注,但缓慢的动力学行为和较大的体积变化限制了其在实际应用中的推广。为了克服这些问题,本研究利用金属有机框架和MoS_(2)的优异性能,设计并制备了具有稳定骨架结构的复合材料。以Co-ZIF为前驱体,添加Mo源材料,在高温硫化烧结的过程中,构建了花状的Co_(9)S_(8)/MoS_(2)/C复合材料,探究其在不同温度条件下的结构和电化学性能。此外,通过密度泛函理论(DFT)分析了Co9S8(001)/MoS2异质结对扩散动力学的影响。结果表明,电子结构在异质结构的界面处发生了重塑,Co_(9)S_(8)/MoS_(2)表现出典型的金属性和显著增强的电子导电性。在所有样品中,700℃合成的阳极材料Co_(9)S_(8)/MoS_(2)/C具有更稳定的结构和优异的电化学性能。当电流密度从4000恢复到40 mA g^(-1)时,Co_(9)S_(8)/MoS_(2)/C-700的放电容量可以从368 mAh g^(-1)完全恢复到571 mAh g^(-1),并稳定在543 mAh g^(-1)。综上所述,本研究提供了一些关于异质结材料合理制备的思路,有助于设计高性能的金属钠离子电池负极复合材料。
文摘以四水合钼酸铵、六水合硝酸钴和硫脲为原料,采用一步水热法在钛网(TM)上原位构筑了不同阵列结构Co_(9)S_(8)/MoS_(2)@TM催化电极。通过改变原料中钴、钼、硫的物质的量之比来调控Co_(9)S_(8)/MoS_(2)@TM电极的结构。采用SEM、XRD和XPS对Co_(9)S_(8)/MoS_(2)@TM进行物相分析和形貌表征,并在1 mol/L KOH电解液中对Co_(9)S_(8)/MoS_(2)@TM的电催化析氧性能进行了研究。结果表明,钴、钼、硫的物质的量之比为10∶14∶600时,制备的Co_(9)S_(8)/MoS_(2)@TM为3D花瓣状阵列结构,且在10 m A/cm^(2)电流密度下过电势为271 m V,塔菲尔斜率为88.5 m V/dec,具有良好的析氧稳定性和耐久性,展现了优异的电化学性能。
基金financial support from Natural Science Foundation of Zhejiang Province(LY21B030005)National Natural Science Foundation of China(51702287).
文摘Transition metal sulfides(TMSs)have been regarded as greatly promising electrode materials for supercapacitors because of abundant redox electroactive sites and outstanding conductivity.Herein,we report a self-supported hierarchical Mn doped Co_(9)S_(8)@Co(OH)_(2) nanosheet arrays on nickel foam(NF)substrate by a one-step metal–organic-framework(MOF)engaged approach and a subsequent sulfurization process.Experimental results reveal that the introduction of manganese endows improved electric conductivity,enlarged electrochemical specific surface area,adjusted electronic structure of Co_(9)S_(8)@Co(OH)_(2) and enhanced interfacial activities as well as facilitated reaction kinetics of electrodes.The optimal Mn doped Co_(9)S_(8)@Co(OH)_(2) electrode exhibits an ultrahigh specific capacitance of 3745 F g^(-1) at 1 A g^(-1)(5.618 F cm^(-2) at 1.5 mA cm^(-2))and sustains 1710 F g^(-1) at 30 A g^(-1)(2.565 F cm^(-2) at 45 mA cm^(-2)),surpassing most reported values on TMSs.Moreover,a battery-type asymmetric supercapacitor(ASC)device is constructed,which delivers high energy density of 50.2 Wh kg^(-1) at power density of 800 W kg^(-1),and outstanding long-term cycling stability(94%capacitance retention after 8000 cycles).The encouraging results might offer an effective strategy to optimize the TMSs for energy-storage devices.
基金supported by ZiQoo Chemical Co.Ltd.,Japan.C.Liu gratefully acknowledges China Scholarship Council(CSC),China.
文摘Designing and fabricating of heterostructured materials with long-term cycling stability and high-rate capacity for the anode of sodium-ion batteries(SIBs)still remain a great challenge.Herein,micro-flower-like MoS_(2)-modified Co_(9)S_(8)(Co_(9)S_(8)/MoS_(2))with a three-dimensional(3D)heterostructure was first obtained via a simple solvothermal synthesis followed by a solid sulfidation treatment process.As a material for the anode of SIBs,the Co_(9)S_(8)/MoS_(2)-based electrode with an initial Co/Mo molar ratio of 1/1(denoted as CM55-S)exhibits the best sodium storage performance with a boosted capacity,superior reversibility(424.5 mAh g^(-1)@2 A g^(-1)at the 1600th cycle,401.1 mAh g^(-1)@5 A g^(-1)at the 800th cycle),and an excellent rate capacity(210.1 mAh g^(-1)@20 A g^(-1)).Density functional theory(DFT)calculations confirm that the Co_(9)S_(8)/MoS_(2)heterostructure has a lower energy barrier(0.30 eV)than the pure Co_(9)S_(8)(0.53 eV).It is expected that such a heterostructured material could be an attractive candidate as the material of the anode for SIBs.
基金support from the National Natural Science Foundation of China(no.52072307)。
文摘Rational structure design and regulation are of paramount importance for obtaining electrode materials with desirable electrochemical performance.Here,a novel binder-free electrode with the hollow Co_(9)S_(8) core@multi-shell structure(CS-x@MXene@Bi_(2)O_(3))derived from metal-organic frameworks(MOFs)precursor is well designed by the electrospinning,sulfuration,carbonization,and hydrothermal processes.In this architecture,the concentration of Co_(9)S_(8)(CS-x)is optimized for an ideal flexible substrate,which alleviates the dimensional variation for long cycle life.The unique cores and the MXene flakes engineered by Bi_(2)O_(3) multiple shells can be responsible for the superior characteristics,including a fast electronic pathway,large specific surface area,enhanced electrical conductivity,and improved electrochemical performance.As expected,the obtained CS-2@MXene@Bi_(2)O_(3) binder-free electrode exhibits a high discharge capacitance of 646.1 F g^(–1)(1 A g^(–1)).Two binder-free electrodes can be assembled into a solid-state supercapacitor with desirable energy and power density,and long-term cyclic stability is demonstrated through 5000 cycles.Given these advantages,the CS-2@MXene@Bi_(2)O_(3) is selected as the electrode in a foldable supercapacitor.More importantly,the specific capacitance is reserved after various deformations.Therefore,it is expected that binder-free electrode materials with the unique core@shell structure design could be applied in wearable and portable energy conversion devices.
