Nano-silicon(nano-Si)and its composites have been regarded as the most promising negative electrode materials for producing the next-generation Li-ion batteries(LIBs),due to their ultrahigh theoretical capacity.Howeve...Nano-silicon(nano-Si)and its composites have been regarded as the most promising negative electrode materials for producing the next-generation Li-ion batteries(LIBs),due to their ultrahigh theoretical capacity.However,the commercial applications of nano Si-based negative electrode materials are constrained by the low cycling stability and high costs.The molten salt electrolysis of SiO_(2)is proven to be suitable to produce nano-Si with the advantages of in-situ microstructure control possibilities,cheap affordability and scale-up process capability.Therefore,an economical approach for electrolysis,with a SiO_(2)/graphite porous electrode as cathode,is adopted to produce nano-Si/graphite composite negative electrode materials(SGNM)in this study.The electrolytic product of the optimized porous electrode is taken as the negative electrode materials for LIBs,and it offers a capacity of 733.2 mAh·g^(-1)and an initial coulombic efficiency of 86.8%in a coin-type cell.Moreover,the capacity of the SGNM retained 74.1%of the initial discharging capacity after 50 cycles at 0.2C,which is significantly higher than that of the simple mixture of silicon and graphite obtained from the formation of silicon carbide(SiC)between nano-Si and graphite particles.Notably,this new approach can be applied to a large-scale production.展开更多
We reported the effects of annealing temperatures on microstructure and electrochemical properties of perovskite-type oxide LaFeO3 prepared by stearic acid combustion method. X-Ray diffraction(XRD) patterns show tha...We reported the effects of annealing temperatures on microstructure and electrochemical properties of perovskite-type oxide LaFeO3 prepared by stearic acid combustion method. X-Ray diffraction(XRD) patterns show that the annealed LaFeO3 powder has orthorhombic structure. Scanning electron microscopy(SEM) and transmission electron microscopy(TEM) images show the presence of homogeneously dispersed, less aggregated, and small crystals(30--40 nm) at annealing temperatures of 500 and 600 ℃. However, as the annealing temperature was increased to 700 and 800 ℃, the crystals began to combine with each other and grew into further larger crystals(90--100 nm). The electrochemical performance of the annealed oxides was measured at 60 ℃ using chronopotentiometry, potentiodynamic polarization, and cyclic voltammetry. As the annealing temperature increased, the discharge capacity and anti-corrosion ability of the oxide electrode first increased and then decreased, reaching the optimum values at 600 ℃, with a maximum discharge capacity of 563 mA-h/g. The better electrochemical performance of LaFeO3 annealed at 600℃ could be ascribed to their smaller and more homogeneous crysals.展开更多
A novel hollow carbon derived from biomass lotus-root has been prepared by a one-step carbonization method.The carbon anode obtained at 900℃ showed the best electrochemical performance,corresponding to a high specifi...A novel hollow carbon derived from biomass lotus-root has been prepared by a one-step carbonization method.The carbon anode obtained at 900℃ showed the best electrochemical performance,corresponding to a high specific capacity of 445 mA·h/g at 0.1 C,as well as excellent cycling stability after 500 cycles.Further investigation exhibits that the lithium storage of hollow carbon involves Li^(+) adsorption in the defect sites and Li^(+) insertion.The results showed that the intrinsic structure of lotus root can inspire us to prepare biomass carbon with a hollow structure as an excellent anode for lithium-ion batteries.展开更多
Vanadium nitride(VN)-based materials have been investigated as negative electrode materials for supercapacitors(SCs)owing to their high theoretical capacitances and suitable negative potential windows.However,viable V...Vanadium nitride(VN)-based materials have been investigated as negative electrode materials for supercapacitors(SCs)owing to their high theoretical capacitances and suitable negative potential windows.However,viable VNbased negative electrode materials suffer from irreversible electrochemical oxidation of the soluble vanadium species,leading to rapid capacitance fading when operated in aqueous electrolytes.Developing a versatile approach to enhance the stability of VN in aqueous electrolytes is still a challenge.Here,an interface engineering strategy is developed to intentionally introduce surface nanolayers of vanadium oxides(VO_(x))as a reactive template on the VN surface to formulate welldesigned polypyrrole@VNO(Ppy@VNO)core-shell nanowires(NWs)incorporated into a 3D porous N-doped graphene(NG)hybrid aerogel as a durable negative electrode for SCs.Experimental and theoretical investigations reveal that the in-situ constructed Ppy@VNO core-shell host can offer more efficient pathways for rapid electron/ion transport and accessible electroactive sites.Most importantly,a reversible surface redox reaction is realized through the transformation of the valence state of V,and a long cyclic stability is achieved.The Ppy@VNO/NG hybrid aerogel can deliver a high specific capacitance of 650 F g^(-1) at 1 A g^(-1) with approximately 70.7%capacitance retention(up to the twenty-fold current density),and an excellent cycling stability without any capacitance decay after 10,000 cycles at both low and high current densities(1 and 10 A g^(-1),respectively).This work paves the way for the development of advanced electrode materials for SCs.展开更多
基金This work was financially supported by the National Key Research and Development Program of China(No.2016YFB0301305)the Talent Plan Project of Beijing(No.2018000097607G378)the National Natural Science Foundation of China(U166420031).
文摘Nano-silicon(nano-Si)and its composites have been regarded as the most promising negative electrode materials for producing the next-generation Li-ion batteries(LIBs),due to their ultrahigh theoretical capacity.However,the commercial applications of nano Si-based negative electrode materials are constrained by the low cycling stability and high costs.The molten salt electrolysis of SiO_(2)is proven to be suitable to produce nano-Si with the advantages of in-situ microstructure control possibilities,cheap affordability and scale-up process capability.Therefore,an economical approach for electrolysis,with a SiO_(2)/graphite porous electrode as cathode,is adopted to produce nano-Si/graphite composite negative electrode materials(SGNM)in this study.The electrolytic product of the optimized porous electrode is taken as the negative electrode materials for LIBs,and it offers a capacity of 733.2 mAh·g^(-1)and an initial coulombic efficiency of 86.8%in a coin-type cell.Moreover,the capacity of the SGNM retained 74.1%of the initial discharging capacity after 50 cycles at 0.2C,which is significantly higher than that of the simple mixture of silicon and graphite obtained from the formation of silicon carbide(SiC)between nano-Si and graphite particles.Notably,this new approach can be applied to a large-scale production.
基金Supported by the National Natural Science Foundation of China(Nos. 51771164, 51571173 and 51701175).
文摘We reported the effects of annealing temperatures on microstructure and electrochemical properties of perovskite-type oxide LaFeO3 prepared by stearic acid combustion method. X-Ray diffraction(XRD) patterns show that the annealed LaFeO3 powder has orthorhombic structure. Scanning electron microscopy(SEM) and transmission electron microscopy(TEM) images show the presence of homogeneously dispersed, less aggregated, and small crystals(30--40 nm) at annealing temperatures of 500 and 600 ℃. However, as the annealing temperature was increased to 700 and 800 ℃, the crystals began to combine with each other and grew into further larger crystals(90--100 nm). The electrochemical performance of the annealed oxides was measured at 60 ℃ using chronopotentiometry, potentiodynamic polarization, and cyclic voltammetry. As the annealing temperature increased, the discharge capacity and anti-corrosion ability of the oxide electrode first increased and then decreased, reaching the optimum values at 600 ℃, with a maximum discharge capacity of 563 mA-h/g. The better electrochemical performance of LaFeO3 annealed at 600℃ could be ascribed to their smaller and more homogeneous crysals.
基金Magnetic Material Testing Centre of Cjlu and the Testing Centre of Cjlu for XRD,SEM,TEM and other measurements.
文摘A novel hollow carbon derived from biomass lotus-root has been prepared by a one-step carbonization method.The carbon anode obtained at 900℃ showed the best electrochemical performance,corresponding to a high specific capacity of 445 mA·h/g at 0.1 C,as well as excellent cycling stability after 500 cycles.Further investigation exhibits that the lithium storage of hollow carbon involves Li^(+) adsorption in the defect sites and Li^(+) insertion.The results showed that the intrinsic structure of lotus root can inspire us to prepare biomass carbon with a hollow structure as an excellent anode for lithium-ion batteries.
基金financially supported by the National Natural Science Foundation of China (52002059 and 51872204)the Belt&Road Young Scientist Exchanges Project of Science and Technology Commission Foundation of Shanghai (20520741000)+3 种基金Shanghai Belt and Road Joint Laboratory of Advanced Fiber and Lowdimension Materials (Donghua University)(18520750400)the Fundamental Research Funds for the Central Universities (20D110631)DHU Distinguished Young Professor Program (LZA2019001)the Open Research Fund of Shanghai Center for High Performance Fibers and Composites and Center for Civil Aviation Composites of Donghua University
文摘Vanadium nitride(VN)-based materials have been investigated as negative electrode materials for supercapacitors(SCs)owing to their high theoretical capacitances and suitable negative potential windows.However,viable VNbased negative electrode materials suffer from irreversible electrochemical oxidation of the soluble vanadium species,leading to rapid capacitance fading when operated in aqueous electrolytes.Developing a versatile approach to enhance the stability of VN in aqueous electrolytes is still a challenge.Here,an interface engineering strategy is developed to intentionally introduce surface nanolayers of vanadium oxides(VO_(x))as a reactive template on the VN surface to formulate welldesigned polypyrrole@VNO(Ppy@VNO)core-shell nanowires(NWs)incorporated into a 3D porous N-doped graphene(NG)hybrid aerogel as a durable negative electrode for SCs.Experimental and theoretical investigations reveal that the in-situ constructed Ppy@VNO core-shell host can offer more efficient pathways for rapid electron/ion transport and accessible electroactive sites.Most importantly,a reversible surface redox reaction is realized through the transformation of the valence state of V,and a long cyclic stability is achieved.The Ppy@VNO/NG hybrid aerogel can deliver a high specific capacitance of 650 F g^(-1) at 1 A g^(-1) with approximately 70.7%capacitance retention(up to the twenty-fold current density),and an excellent cycling stability without any capacitance decay after 10,000 cycles at both low and high current densities(1 and 10 A g^(-1),respectively).This work paves the way for the development of advanced electrode materials for SCs.