Using low-cost FePO4·2H2O as iron source,Na2FePO4F/C composite is prepared by alcohol-assisted ball milling and solid-state reaction method.The XRD pattern of Na2FePO4F/C composite demonstrates sharp peaks,indica...Using low-cost FePO4·2H2O as iron source,Na2FePO4F/C composite is prepared by alcohol-assisted ball milling and solid-state reaction method.The XRD pattern of Na2FePO4F/C composite demonstrates sharp peaks,indicating high crystalline and phase purity.The SEM and TEM images reveal that diameter of the spherical-like Na2FePO4F/C particles ranges from 50 to 300 nm,and HRTEM image shows that the surface of Na2FePO4F/C composite is uniformly coated by carbon layer with a average thickness of about 3.6 nm.The carbon coating constrains the growth of the particles and effectively reduces the agglomeration of nanoparticles.Using lithium metal as anode,the composite delivers a discharge capacities of 102.8,96.4 and 90.3 mA·h/g at rates of 0.5C,1C and 2C,respectively.After 100 cycles at 0.5C,a discharge capacity of 98.9 mA·h/g is maintained with capacity retention of 96.2%.The Li+diffusion coefficient(D)of Na2FePO4F/C composite is calculated as 1.71×10^–9 cm^2/s.This study reveals that the simple solid state reaction could be a practical and effective synthetic route for the industrial production of Na2FePO4F/C material.展开更多
Aqueous rechargeable batteries are a possible strategy for large-scale energy storage systems.However,limited choices of anode materials restrict their further application.Here we report phenazine(PNZ)as stable anode ...Aqueous rechargeable batteries are a possible strategy for large-scale energy storage systems.However,limited choices of anode materials restrict their further application.Here we report phenazine(PNZ)as stable anode materials in different alkali-ion(Li+,Na+,K+)electrolyte.A novel full cell is assembled by phenazine anode,Na0.44MnO2 cathode and 10 M NaOH electrolyte to further explore the electrochemical performance of phenazine anode.This battery is able to achieve high capacity(176.7 mAh·g^−1 at 4 C(1.2·Ag^−1)),ultralong cycling life(capacity retention of 80%after 13,000 cycles at 4 C),and excellent rate capacity(92 mAh·g^−1 at 100 C(30 A·g^−1)).The reaction mechanism of PNZ during charge—discharge process is demonstrated by in situ Raman spectroscopy,in situ Fourier transform infrared(FTIR)spectroscopy,X-ray photoelectron spectroscopy(XPS)and density functional theory(DFT)calculations.Furthermore,the system is able to successfully operate at wide temperature range from−20 to 70°C and achieves remarkable electrochemical performance.展开更多
基金Projects(51472211,51502256)supported by the National Natural Science Foundation of ChinaProjects(2016GK4005,2016GK4030)supported by the Strategic New Industry of Hunan Province,ChinaProject(13C925)supported by the Research Foundation of Education Bureau of Hunan Province,China
文摘Using low-cost FePO4·2H2O as iron source,Na2FePO4F/C composite is prepared by alcohol-assisted ball milling and solid-state reaction method.The XRD pattern of Na2FePO4F/C composite demonstrates sharp peaks,indicating high crystalline and phase purity.The SEM and TEM images reveal that diameter of the spherical-like Na2FePO4F/C particles ranges from 50 to 300 nm,and HRTEM image shows that the surface of Na2FePO4F/C composite is uniformly coated by carbon layer with a average thickness of about 3.6 nm.The carbon coating constrains the growth of the particles and effectively reduces the agglomeration of nanoparticles.Using lithium metal as anode,the composite delivers a discharge capacities of 102.8,96.4 and 90.3 mA·h/g at rates of 0.5C,1C and 2C,respectively.After 100 cycles at 0.5C,a discharge capacity of 98.9 mA·h/g is maintained with capacity retention of 96.2%.The Li+diffusion coefficient(D)of Na2FePO4F/C composite is calculated as 1.71×10^–9 cm^2/s.This study reveals that the simple solid state reaction could be a practical and effective synthetic route for the industrial production of Na2FePO4F/C material.
基金This study was supported by the National Key R&D Program of China(Nos.2016YFB0901500 and 2016YFB0101201)the National Natural Science Foundation of China(No.51771094)+1 种基金Ministry of Education of China(Nos.B12015 and IRT13R30)Tianjin High-Tech(No.18JCZDJC31500).
文摘Aqueous rechargeable batteries are a possible strategy for large-scale energy storage systems.However,limited choices of anode materials restrict their further application.Here we report phenazine(PNZ)as stable anode materials in different alkali-ion(Li+,Na+,K+)electrolyte.A novel full cell is assembled by phenazine anode,Na0.44MnO2 cathode and 10 M NaOH electrolyte to further explore the electrochemical performance of phenazine anode.This battery is able to achieve high capacity(176.7 mAh·g^−1 at 4 C(1.2·Ag^−1)),ultralong cycling life(capacity retention of 80%after 13,000 cycles at 4 C),and excellent rate capacity(92 mAh·g^−1 at 100 C(30 A·g^−1)).The reaction mechanism of PNZ during charge—discharge process is demonstrated by in situ Raman spectroscopy,in situ Fourier transform infrared(FTIR)spectroscopy,X-ray photoelectron spectroscopy(XPS)and density functional theory(DFT)calculations.Furthermore,the system is able to successfully operate at wide temperature range from−20 to 70°C and achieves remarkable electrochemical performance.
