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1.
Three-dimensional hierarchical Co3O4@C hollow microspheres (Co3O4@C HSs) are successfully fabricated by a facile and scalable method. The Co3O4@C HSs are composed of numerous Co3O4 nanoparticles uniformly coated by a thin layer of carbon. Due to its stable 3D hierarchical hollow structure and uniform carbon coating, the Co3O4@C HSs exhibit excellent electrochemical performance as an anode material for lithium-ion batteries (LIBs). The Co3O4@C HSs electrode delivers a high reversible specific capacity, excellent cycling stability (1672 mAh g?1 after 100 cycles at 0.2 A g?1 and 842.7 mAh g?1 after 600 cycles at 1 A g?1), and prominent rate performance (580.9 mAh g?1 at 5 A g?1). The excellent electrochemical performance makes this 3D hierarchical Co3O4@C HS a potential candidate for the anode materials of the next-generation LIBs. In addition, this simple synthetic strategy should also be applicable for synthesizing other 3D hierarchical metal oxide/C composites for energy storage and conversion.  相似文献   

2.
A Co3O4/vapor-grown carbon fiber (VGCF) hybrid material is prepared by a facile approach, namely, via liquid-phase carbonate precipitation followed by thermal decomposition of the precipitate at 380 °C for 2 h in argon gas flow. The material is characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Brunauer-Emmett-Teller specific surface area analysis, and carbon elemental analysis. The Co3O4 in the hybrid material exhibits the morphology of porous submicron secondary particles which are self assembled from enormous cubic-phase crystalline Co3O4 nanograins. The electrochemical performance of the hybrid as a high-capacity conversion-type anode material for lithium-ion batteries is investigated by cyclic voltammetry, electrochemical impedance spectroscopy, and galvanostatic discharge/charge methods. The hybrid material demonstrates high specific capacity, good rate capability, and good long-term cyclability, which are far superior to those of the pristine Co3O4 material prepared under similar conditions. For example, the reversible charge capacities of the hybrid can reach 1100–1150 mAh g?1 at a lower current density of 0.1 or 0.2 A g?1 and remain 600 mAh g?1 at the high current density of 5 A g?1. After 300 cycles at 0.5 A g?1, a high charge capacity of 850 mAh g?1 is retained. The enhanced electrochemical performance is attributed to the incorporated VGCFs as well as the porous structure and the smaller nanograins of the Co3O4 active material.  相似文献   

3.
A simple sucrose-assisted combustion and subsequent high-temperature calcination route have been employed to prepare hierarchical porous ZnMn2O4 nanostructure. When used as an electrode for supercapacitor, the ZnMn2O4 electrode displays a high specific capacitance of 411.75 F g?1 at a current density of 1 A g?1, remarkable capacitance retention rate of 64.28 % at current density of 32 A g?1 compared with 1 A g?1, as well as excellent cycle stability (reversible capacity retention of 88.32 % after 4000 cycles). The outstanding electrochemical performances are mainly attributed to its hierarchical porous architecture, which provides large reaction surface area, fast ion and electron transfer, and good structure stability. All these impressive results demonstrate that ZnMn2O4 shows promise for its application in supercapacitors.  相似文献   

4.
A dandelion-like mesoporous Co3O4 was fabricated and employed as anode materials of lithium ion batteries (LIBs). The architecture and electrochemical performance of dandelion-like mesoporous Co3O4 were investigated through structure characterization and galvanostatic charge/discharge test. The as-prepared dandelion-like mesoporous Co3O4 consisted of well-distributed nanoneedles (about 40 nm in width and about 5 μm in length) with rich micropores. Electrochemical experiments illustrated that the as-prepared dandelion-like mesoporous Co3O4 as anode materials of LIBs exhibited high reversible specific capacity of 1430.0 mA h g?1 and 1013.4 mA h g?1 at the current density of 0.2 A g?1 for the first and 100th cycle, respectively. The outstanding lithium storage properties of the as-prepared dandelion-like mesoporous Co3O4 might be attributed to its dandelion-like mesoporous nanostructure together with an open space between adjacent nanoneedle networks promoting the intercalation/deintercalation of lithium ions and the charge transfer on the electrode. The enhanced capacity as well as its high-rate capability made the as-prepared dandelion-like mesoporous Co3O4 to be a good candidate as a high-performance anode material for LIBs.  相似文献   

5.
ZnCo2O4 nanoflakes were directly grown on Ni foam via a two-step facile strategy, involving cathodic electrolytic electrodeposition (ELD) method and followed by a thermal annealing treatment step. The results of physical characterizations exhibit that the mesoporous ZnCo2O4 nanoflakes have large electroactive surface areas (138.8 m2 g?1) and acceptable physical stability with the Ni foam, providing fast electron and ion transport sites. The ZnCo2O4 nanoflakes on Ni foam were directly used as integrated electrodes for supercapacitors and their electrochemical properties were measured in 2 M KOH aqueous solution. The ZnCo2O4 nanoflake electrode exhibits a high capacitance of 1781.7 F g?1 at a current density of 5 A g?1 and good rate capability (62% capacity retention at 50 A g?1). Also, an excellent cycling ability at various current densities from 5 to 50 A g?1 was obtained and 92% of the initial capacitance maintained after 4000 cycles. The results demonstrate that the proposed synthesis route is cost-effective and facile and can be developed for preparation of electrode materials in other electrochemical supercapacitors.  相似文献   

6.
One-dimensional Co2+-doped Li4Ti5O12 nanofibers with a diameter of approximately 500 nm have been synthesized via a one-step controllable electrospinning method. The Co2+-doped Li4Ti5O12 nanofibers were systematically characterized by XRD, ICP, TEM, SEM, BET, EDS mapping, and XPS. Based on the cubic spinel structure and one-dimensional effect of Li4Ti5O12, Co2+-doped Li4Ti5O12 nanofibers exhibit the enlarged lattice volume, reduced particle size and enhanced electrical conductivity. More importantly, Co2+-doped Li4Ti5O12 nanofibers as a lithium ion battery anode electrode performs superior electrochemical performance than undoped Li4Ti5O12 electrode in terms of electrochemical measurements. Particularly, the reversible capacity of Co2+-doped Li4Ti5O12 electrode reaches up to 140.1 mAh g?1 and still maintains 136.5 mAh g?1 after 200 cycles at a current rate of 5 C. Therefore, one-dimensional Co2+-doped Li4Ti5O12 nanofiber electrodes, showing high reversible capacity and remarkable recycling property, could be a potential candidate as an anode material.  相似文献   

7.
To suppress the capacity fade of Li-rich Li1.2Ni0.13Co0.13Mn0.54O2 material as cathode materials for lithium-ion battery, we introduce a LiF coating layer on the surface to improve the cycling performance of Li1.2Ni0.13Co0.13Mn0.54O2 material. The modified sample shows a capacity of 163.2 mAh g?1 with a capacity retention of 95% after 100 cycles at a current density of 250 mA g?1, while the pristine sample only delivers a capacity of 129.9 mAh g?1 with a capacity retention of 82%. Compared with the pristine material, the LiF-modified sample exhibits an obvious enhancement in the electrochemical performance, which will be very beneficial for this material to be commercialized on the new energy vehicles and other related areas.  相似文献   

8.
Yuan Xia  Hui Wang 《Ionics》2016,22(2):159-166
Different particle sizes of dodecahedron precursors are synthesized by controlling the polarity of the solution. Through the results of scanning electron microscope (SEM) images, it can be found that different particle sizes of precursors present obvious edge angles and their morphology can be well retained after annealing. X-ray diffraction (XRD) measurements suggest that the annealed polyhedral products are pure single-phase NiCo2O4. When tested as lithium-ion battery anode, 0.5 μm NiCo2O4 polyhedra exhibits a specific capacity of 1050 mAh g?1 at 0.1 C at the 60th cycle, which was higher than theoretical capacity of single metal oxide (NiO 718 mAh g?1 and Co3O4 890 mAh g?1). It also exhibits the highest rate capability with an average discharge capacity of 890, 700, 490, 330, and 300 mAh g?1 at 0.5, 2, 4, 8, and 10 C, respectively. Those advantages are attributed to that small-sized particle with great surface areas decrease the actual current density at the surface and inner of the prepared electrode.  相似文献   

9.
The layered Li1.2Mn0.54Ni0.13Co0.13O2 lithium-rich manganese-based solid solution cathode material has been synthesized by a simple solid-state method. The as-prepared material has a typical layered structure with R-3m and C2/m space group. The synthesized Li1.2Mn0.54Ni0.13Co0.13O2 has an irregular shape with the size range from 200 to 500 nm, and the primary particle of Li1.2Mn0.54Ni0.13Co0.13O2 has regular sphere morphology with a diameter of 320 nm. Electrochemical performances also have been investigated. The results show that the cathode material Li1.2Mn0.54Ni0.13Co0.13O2 prepared at 900 °C for 12 h has a good electrochemical performance, which can deliver a high initial discharge capacity of 233.5, 214.2, 199.3, and 168.1 mAh g?1 at 0.1, 0.2, 0.5, and 1 C, respectively. After 50 cycles, the capacity retains 178.0, 166.3, 162.1, and 155.9 mAh g?1 at 0.1, 0.2, 0.5, and 1 C, respectively. The results indicate that the simple method has a great potential in synthesizing manganese-based cathode materials for Li-ion batteries.  相似文献   

10.
Lithium-rich cathode material Li[Li0.2Ni0.13Co0.13Mn0.54]O2 doped with trace Mo is successfully synthesized by a sol-gel method. The X-ray diffraction patterns show that trace Mo substitution increases the inter-layer space of the material, of which is benefiting to lithium ion insertion/extraction among the electrode materials. The (CV) tests demonstrate the decrease of polarization, and on the other hand, the lithium ion diffusion coefficient (D Li) of the modified material turns out to be larger, which indicates a faster electrochemical process. As a result, the Mo doped material possesses high rate performance and good cycling stability, and the initial discharge capacity reaches 149.3 mAh g?1 at a current density of 5.0 °C, and the residual capacity is 144.0 mAh g?1 after 50 cycles with capacity retention of 96.5 % in the potential range of 2.0–4.8 V at room temperature.  相似文献   

11.
Yttrium fluoride YF3 layer with different coating contents is successfully covered on the surface of Li1.2Mn0.54Ni0.13Co0.13O2 via a common wet chemical approach. The XRD, SEM, TEM, and charge-discharge tests are applied to investigate the influence of YF3 layer on the micro-structural, morphology, and electrochemical properties of Li1.2Mn0.54Ni0.13Co0.13O2. And the electrochemical test results demonstrate that the YF3-coated LMNCO samples exhibit the improved electrochemical properties. The 2wt.%YF3-coated LMNCO delivers a discharge capacity of 116.6 mAh g?1 at 5 C rate, much larger than that (95.6 mAh g?1) of the pristine one. Besides, the electrochemical impedance spectroscopy (EIS) and cyclic voltammetric results indicate that the YF3 coating layer can promote the optimization formation of SEI film and reversibility of the electrochemical redox.  相似文献   

12.
LiNi0.5Co0.2Mn0.3O2 particles of uniform size were prepared through carbonate co-precipitation method with acacia gum. The precursor of carbonate mixture was calcined at 800 °C, and a well-crystallized Ni-rich layered oxide was got. The phase structure and morphology were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The micro-sized particles delivered high initial discharge capacity of 164.3 mA h g?1 at 0.5 C (1 C?=?200 mA g?1) between 2.5 and 4.3 V with capacity retention of 87.5 % after 100 cycles. High reversible discharge capacities of 172.4 and 131.4 mA h g?1 were obtained at current density of 0.1 and 5 C, respectively. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were performed to further study the LiNi0.5Co0.2Mn0.3O2 particles. Anyway, the excellent electrochemical performances of LiNi0.5Co0.2Mn0.3O2 sample should be attributed to the use of acacia gum.  相似文献   

13.
A flexible Co3O4 hollow microsphere/graphene/carbon nanotube hybrid film is successfully prepared through a facile filtration strategy and a subsequent thermally treated process. The composition, morphology, and structure of the as-prepared film are characterized by X-ray diffraction, X-ray photoelectron spectrometer, scanning electron microscopy, and transmission electron microscopy. Based on the morphology characterizations on the hybrid film, the Co3O4 hollow microspheres are uniformly and closely attached on three-dimensional (3D) graphene/carbon nanotubes (GR/CNTs) network, which decreases the agglomeration of Co3O4 microspheres effectively. In this hybrid film, the 3D GR/CNT network which enhances conductance as well as prevents aggregation is a benefit to help Co3O4 to exert its lithium storage capabilities sufficiently. When used as a binder-free anode material for lithium-ion batteries, the hybrid film delivers excellent electrochemical properties involving reversible capacity (863 mAh g?1 at a current density of 100 mA g?1) and rate performance (185 mAh g?1 at a current density of 1600 mA g?1).  相似文献   

14.
The LaF3-coated Li[Li0.2Mn0.54Ni0.13Co0.13]O2 nanoparticles were synthesized via co-precipitation method followed by simple chemical deposition process. The crystal structure, particle morphology, and electrochemical properties of the bare and coated materials were studied by XRD, SEM, TEM, charge–discharge tests. The results showed that the surface coating on Li[Li0.2Mn0.54Ni0.13Co0.13]O2 nanoparticles were amorphous LaF3 layer with a thickness of about 10–30 nm. After the surface modification with LaF3 films, the coating layer served as a protective layer to suppress the side reaction between the positive electrode and electrolyte, and the Li[Li0.2Mn0.54Ni0.13Co0.13]O2 oxide demonstrated the improved electrochemical properties. The LaF3-coated Li[Li0.2Mn0.54Ni0.13Co0.13]O2 electrode delivered the capacities of 270.5, 247.9, 197.1, 170.0, 142.7, and 109.5 mAh g?1 at current rates of 0.1, 0.2, 0.5, 1, 2, and 5 C rate, respectively. Besides, the capacity retention was increased from 85.1 to 94.8 % after 100 cycles at 0.5 C rate. It implied surface modification with LaF3 played an important role to improve the cyclic stability and rate capacity of the Li-rich nickel manganese oxides.  相似文献   

15.
A novel hydrothermal emulsion method is proposed to synthesize mesoporous NiMoO4 nanosphere electrode material. The size of sphere-shaped NiMoO4 nanostructure is controlled by the mass ratio of water and oil phases. Nickel acetate tetrahydrate and ammonium heptamolybdate were used as nickel and molybdate precursors, respectively. The resultant mesoporous NiMoO4 nanospheres were characterized by X-ray diffraction, N2 adsorption and desorption, scanning electron microscopy, and transmission electron microscopy. The electrochemical performances were evaluated by cyclic voltammetry (CV), cyclic chronopotentiometry (CP), and electrochemical impedance spectroscopy (EIS) in 6 M KOH solution. The typical mesoporous NiMoO4 nanospheres exhibit the large specific surface area of 113 m2 g?1 and high specific capacitance of 1443 F g?1 at 1 A g?1, an outstanding cyclic stability with a capacitance retention of 90 % after 3000 cycles of charge-discharge at a current density of 10 A g?1, and a low resistance.  相似文献   

16.
Guoqiang Liu  Lei Wen  Yue Li  Yulong Kou 《Ionics》2015,21(4):1011-1016
The pure phase P2-Na2/3Ni1/3Mn2/3O2 was synthesized by a solid reaction process. The optimum calcination temperature was 850 °C. The as-prepared product delivered a capacity of 158 mAh g?1 in the voltage range of 2–4.5 V, and there was a phase transition from P2 to O2 at about 4.2 V in the charge process. The P2 phase exhibited excellent intercalation behavior of Na ions. The reversible capacity is about 88.5 mAh g?1 at 0.1 C in the voltage range of 2–4 V at room temperature. At an elevated temperature of 55 °C, it could remain as an excellent capacity retention at low current rates. The P2-Na2/3Ni1/3Mn2/3O2 is a potential cathode material for sodium-ion batteries.  相似文献   

17.
The Li-rich cathode material Li[Li0.2Mn0.54Ni0.13Co0.13]O2 had been successfully synthesized by a carbonate coprecipitation method. The effects of substituting traces of Al element for different transitional metal elements on the crystal structure and surface morphology had been investigated by X-ray diffraction (XRD) and field emission scanning electron microscopy. The results revealed that all the materials showed similar XRD patterns and surface morphology. It was demonstrated that LNCMAl1 exhibited the superior electrochemical performance. The discharge capacity was 265.2 mAh g?1 at 0.1 C and still maintained a discharge capacity of 135.6 mAh g?1 at 5.0 C. The capacity retention could still be 58.2 and 66.8% after 50 cycles at 1.0 and 2.0 C, respectively. Electrochemical impedance spectra results proved that the remarkably improved rate capability and cycling performance could be ascribed to the low charge transfer resistance and enhanced reaction kinetics.  相似文献   

18.
Al-doped ZnO (AZO) was sputtered on the surface of LiNi1/3Co1/3Mn1/3O2 (NCM) thin film electrode via radio frequency magnetron sputtering, which was demonstrated to be a useful approach to enhance electrochemical performance of thin film electrode. The structure and morphology of the prepared electrodes were characterized by X-ray diffraction, scanning electron microscopy, energy dispersive spectrometer, and transmission electron microscopy techniques. The results clearly demonstrated that NCM thin film showed a strong (104) preferred orientation and AZO was uniformly covered on the surface of NCM electrode. After 200 cycles at 50 μA μm?1 cm?2, the NCM/AZO-60s electrode delivered highest discharge capacity (78.1 μAh μm?1 cm?2) compared with that of the NCM/AZO-120s electrode (62.4 μAh μm?1 cm?2) and the bare NCM electrode (22.3 μAh μm?1 cm?2). In addition, the rate capability of the NCM/AZO-60s electrode was superior to the NCM/AZO-120s and bare NCM electrodes. The improved electrochemical performance can be ascribed to the appropriate thickness of the AZO coating layer, which not only acted as HF scavenger to keep a stable electrode/electrolyte interface but also reduced the charge transfer resistance during cycling.  相似文献   

19.
Layered lithium-enriched nickel manganese oxides Li1.2Ni0.2Mn0.6O2 have been synthesized and coated by fast ionic conductor Li3VO4 with varying amounts (1, 3, and 5 wt%) in this paper. The effect of Li3VO4 on the physical and electrochemical properties of Li1.2Ni0.2Mn0.6O2 has been discussed through the characterizations of X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscope (TEM), discharge, cyclic performance, rate capability, and electrochemical impedance spectroscopy (EIS). The discharge capacity and coulomb efficiency of Li1.2Ni0.2Mn0.6O2 in the first cycle have been improved after Li3VO4 coating. And, the 3 wt% Li3VO4-coated Li1.2Ni0.2Mn0.6O2 shows the best discharge capacity (246.8 mAh g?1), capacity retention (97.3 % for 50 cycles), and rate capability (90.4 mAh g?1 at 10 C). Electrochemical impedance spectroscopy (EIS) results show that the R ct of Li1.2Ni0.2Mn0.6O2 electrode decreases after Li3VO4 coating, which is due to high lithium ion diffusion coefficient of Li3VO4, is responsible for superior rate capability.  相似文献   

20.
Nanocrystalline Li2TiO3 was successfully synthesized using solid-state reaction method. The microstructural and electrochemical properties of the prepared material are systematically characterized. The X-ray diffraction pattern of the prepared material exhibits predominant (002) orientation related to the monoclinic structure with C2/c space group. HRTEM images and SAED analysis reveal the well-developed nanostructured particles with average size of ~40 nm. The electrochemical properties of the prepared sample are carried out using cyclic voltammetry (CV) and chronopotentiometry (CP) using Pt//Li2TiO3 cell in 1 mol L?1 Li2SO4 aqueous electrolyte. The Li2TiO3 electrode exhibits a specific discharge capacity of 122 mAh g?1; it can be used as anode in Li battery within the potential window 0.0–1.0 V, while investigated as a supercapacitor electrode, it delivers a specific capacitance of 317 F g?1 at a current density of 1 mA g?1 within the potential range ?0.4 to +0.4 V. The demonstration of both anodic and supercapacitor behavior concludes that the nanocrystalline Li2TiO3 is a suitable electrode material for supercapattery application.  相似文献   

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