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Transition metal oxides@carbon(C) nanocomposites with hierarchical three-dimensional (3D) core-shell nanoarchitectures, large surface area and high electrical conductivity as anode materials for lithium ion batteries (LIBs) are very desirable. Herein, we developed a simple and feasible route to fabricate novel hierarchical 3D ball-in-ball ZnO/ZnFe 2 O 4 @C nanospheres with well-defined hollow microstructures via one-step carbonization of Zn/Fe-metal organic frameworks for the first time. The as-prepared hierarchical 3D ball-in-ball ZnO/ZnFe 2 O 4 @C nanospheres were carefully characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, X-ray powder diffraction, thermogravimetric analysis, N 2 adsorption/desorption isotherm, transmission electron microscopy and electrochemical techniques. The results showed ultrafine ZnO and ZnFe 2 O 4 nanocrystals were uniformly encapsulated by few carbon layers which was derived from in-situ carbonization of the organic ligands. Benefiting from their special hollow nanoarchitectures, ultrafine ZnO and ZnFe 2 O 4 nanocrystals encapsulated by a few carbon layers, large specific surface area and high electrical conductivity, the hierarchical 3D ball-in-ball ZnO/ZnFe 2 O 4 @C nanospheres presented high reversible capacities of 1283 and 1100 mA h g −1 after first 100 cycles and the following 100 cycles at current density of 100 and 200 mA g −1 , respectively. A high specific capacity of 155 mA h g −1 was obtained at relatively large current rates of 20 A g −1 . [ABSTRACT FROM AUTHOR]

Porous MnO@C core-shell nanowires were prepared via a simple and facile method. The morphologies, the phase purity, the mass contents, and the BET surface area of the composite were characterized by SEM, XRD, TGA, and N2 adsorption test, respectively. When the composite served as an anode for lithium-ion batteries, it showed superior electrochemical performances. The MnO@C composite presented a reversible capacity of 448.1 mAh g−1 after 100 cycles at the current rate of 200 mA g−1. [ABSTRACT FROM AUTHOR]

Inferior specific capacity and sluggish redox kinetics are the most stubborn problems lithium-ion and lithium-sulfur batteries (LIBs and LSBs) are facing, respectively. Here we report a facile fabrication of self-supported hollow Co 3 O 4 @carbon nanotubes on carbon cloth (H-Co 3 O 4 @CNT/CC) through a mild pyrolysis-oxidation process. The additive- and binder-free H-Co 3 O 4 @CNT/CC shows excellent electrochemical performances as both LIBs and LSBs electrodes. As a robust integrated anode for LIBs, the areal capacities are 2.72 mAh cm−2 at the current density of 0.5 C over 1000 cycles. While as a durable cathode host for LSBs, favorable areal capacities of 2.37 mAh cm−2 are maintained with a low capacity decay of 0.11 % per cycle at the sulfur loading of 6 mg cm−2 and current density of 1 C after 400 cycles. Electrochemical technology, ex situ Raman spectroscopy and DFT calculations are performed to comprehensively analyze H-Co 3 O 4 @CNT/CC via thermodynamics and kinetics. It is demonstrated that the hierarchically hollow interior structure, strong adsorb ability of Co 3 O 4 toward polysulfides and three-dimensional (3D) inter-connected conductive carbon framework are responsible for the high areal capacity, fast redox kinetics and cycling durability. [Display omitted] • The integrated electrode possesses the merits of hollow nanostructured Co 3 O 4 and 3D inter-connected conductive network. • Electrochemical technology and DFT calculations are performed to comprehensively analyze H-Co 3 O 4 @CNT/CC. • H-Co 3 O 4 @CNT/CC delivers high areal capacities of 2.72 mAh cm-2 after 1000 cycles at 0.5 C as anode. [ABSTRACT FROM AUTHOR]

In this work, we demonstrated an accessible and facile method to prepare hierarchically porous carbon (HPC)/Co 3 O 4 nanocomposites (HPCC). Biomaterials-derived HPC was used as the appropriate carrier to load Co 3 O 4 nanoparticles due to its hierarchically porous structure and high surface area of 163 m 2 g −1 . The HPCC nanocomposites were used as an anode material for lithium-ion batteries (LIBs) and showed good electrochemical performance, delivering an initial discharge of 1566 and charge capacity of 1314 mA h g −1 with a initial coulombic efficiency of 83.9%. Additionally, it could still maintain a high reversible capacity of 1215 mA h g −1 after 100 cycles at a specific current of 100 mA g −1 , which is much better than that of HPC, and Co 3 O 4 and some Co 3 O 4 -based nanocomposites. The good electrochemical performance was mainly attributed to the good distribution of small Co 3 O 4 on HPC, the high surface area and hierarchical pores of HPC to effectively load a number of small Co 3 O 4 , alleviate the severe volume expansion during cycling and improve the electrical conductivity of nanocomposites, and the synergistic effects from the HPC and Co 3 O 4 . Therefore, the HPCC nanocomposites were expected to be an advanced anode material for LIBs. [ABSTRACT FROM AUTHOR]

Hollow nitrogen (N)-doped Fe 3 O 4 /carbon (C) nanocages with hierarchical porosities have been successfully synthesized by carbonizing polydopamine (PDA)-coated Prussian blue (PB). Scanning electron microscopy, transmission electron microscopy, X-ray powder diffraction, X-ray photoelectron spectroscopy and N 2 adsorption/desorption isotherms were employed to characterize the hollow N-doped Fe 3 O 4 /C superstructures. Owing to their well-defined hierarchical porous structure and high electric conductivity originated from N-doped carbon matrix, the unique hollow nanocages as anode materials for Lithium ion batteries (LIBs) exhibited a specific capacity of 878.7 mA h g −1 after 200 cycles at the specific current of 200 mA g −1 , which is much better than that of N-doped Fe 3 O 4 /C derived from pure PB (merely 547 mA h g −1 ). The novel construction with hollow interior nanoarchitecture, hierarchical porosity, high electrical conductivity, N-doped carbon, and the Fe 3 O 4 nanoparticles incorporated into porous interconnected carbon framework make the special nanocomposites be very promising Fe 3 O 4 -based anode materials. [ABSTRACT FROM AUTHOR]

The search of advanced anodes has been an important way to satisfy the ever-growing demands on high rate performance lithium-ion batteries (LIBs). It was observed that the capacity of Fe 3 C as an anode is larger than its theoretical one, which might be attributed to the pseudocapacity on the interface between the carbide and electrolyte. In this work, a novel carbon sphere doped with Fe 3 C nanoparticles was fabricated and tested as the anode in LIBs. In the first place, iron precursors were embedded in the cross-link polymer resorcinol-formaldehyde (RF) spheres via a facile hydrothermal reaction, in which RF served as the carbon source and ethanol as a dispersant agent. Consequently, the hydrothermal products were carbonized successively at 700 °C under inert atmosphere to obtain porous carbon spheres doped with Fe 3 C. When the composite severed as an anode in LIBs, its discharge capacity increased to the largest during the first 250-400 cycles, then dropped down to a similar level of that after 1000 cycles at different current rates. The discharge capacity of the composite increased from ∼300 mAh g −1 to ∼540 mAh g −1 at the current of 100 mA g −1 during the initial hundreds cycles, and even a discharge capacity of ∼230 mAh g −1 at the current of 2000 mA g −1 . Moreover, it was observed that a discharge plateau gradually appeared between 0.7∼1.1 V during the first hundreds of cycles. The electrochemical behaviors of the anode before 1000 discharge/charge cycles were compared with that after 1000 discharge/charge cycles by cyclic voltammetry and electrochemical impedance spectroscopy to find out the differences between their features. The high rate performance of LIBs might result from the decomposition of electrolyte and the pseudocapacity behavior presented on the interfacial (surface) lithium storage of the active materials. [ABSTRACT FROM AUTHOR]

In the contemporary era, energy demands are ever-growing and a significant number of people are concerned about environmental pollution caused by the burning of fossil fuels. Therefore, it is a striking problem for the researchers to pursue renewable energy and sustainable energy to deal with the environmental and energy crisis. In this work, a novel hybrid hollow porous ZnO/C nanocages with high specific surface areas of 256 m 2 g −1 and high carbon content in weight of about 50% used as anode materials for lithium ion batteries (LIBs) were synthesized by a one-step pyrolysis of hollow metal organic framework material MOF-5 as both precursor and self-sacrificing template under N 2 atmosphere. The hollow porous ZnO/C nanocages released an initial discharge capacity of 1928 mA h g −1 at the current density of 100 mA g −1 and remained a high reversible capacity of 750 mA h g −1 after 100 cycles. According to the results of electrochemical measurements, the hollow porous ZnO/C nanocages also showed a good rate capability of 351 mA h g −1 at a relative large current density of 2 A g −1 . The excellent electrochemical performance was mainly due to the special nanostructures of the fabricated materials. Hence, the as-resulted hollow porous ZnO/C nanocages are promising anode materials for LIBs. [ABSTRACT FROM AUTHOR]

Hollow multicomponent transition metal oxide nanostructures have caused extensive attention due to their enhanced performances in lithium-ion batteries (LIBs). Herein, a hybrid of multicomponent 3NiO·2Ni 3/2 Co 1/2 ZnO 4 nanocomposite with porous hollow dodecahedron nanostructures (3NiO·2Ni 3/2 Co 1/2 ZnO 4 -HD) was fabricated by carbonization of NiCoZn-layered double hydroxides which were derived from multimetallic zeolitic imidazolate frameworks (Zn/Co-ZIFs) as both self-sacrificial template and precursors. The 3NiO·2Ni 3/2 Co 1/2 ZnO 4 -HD nanocomposites were carefully characterized by various techniques including scanning electron microscopy, X-ray powder diffraction, X-ray photoelectron spectroscopy, thermogravimetric analysis, N 2 adsorption/desorption, transmission electron microscopy, Four-Point Probes and electrochemical techniques. When the 3NiO·2Ni 3/2 Co 1/2 ZnO 4 -HD nanocomposites were acted as anode materials for LIBs, a capacity of about 1337 mA h g −1 could be obtained after 100 cycles. The improved electrochemical performances might originate from synergistic effect of multicomponents, enhanced electrical conductivity and porous hollow dodecahedron nanostructures which could effectively alleviate volume deformation in the process of discharge/charge, accelerate mass transfer and increase the active sites for Li + storage. [ABSTRACT FROM AUTHOR]

Novel porous cage-like carbon (C)/nano-Si nanocomposites as anode materials for lithium-ion batteries (LIBs) was prepared based on nano-Si@zeolitic imidazolate frameworks (ZIF-8)-templated method. In this strategy, p-aminobenzoic acid was initially grafted onto nano-Si to form benzoic acid-functionalized nano-Si, and then nano-Si@ZIF-8 was constructed by alternately growing Zn(NO 3 ) 2 ·6H 2 O and 2-methylimidazolate on benzoic acid-functionalized nano-Si under ultrasound. The novel porous cage-like nano-Si/C nanocomposites were fabricated by pyrolyzing the resulted nano-Si@ZIF-8 and washing with HCl to remove off ZnO. Scanning electron microscopy, transmission electron microscopy, X-ray powder diffraction, Raman spectra and N 2 adsorption/desorption isotherms were employed to characterize the porous cage-like nano-Si/C nanocomposites. The resulted nano-Si/C nanocomposites as anode materials for LIBs showed a high reversible capacity of ∼1168 mA h g −1 at 100 mA g −1 after 100 cycles, which was higher than many previously reported Si/C nanocomposites. The porous nanostructure, high specific surface area and good electrical conductivity of the cage-like nano-Si/C nanocomposites contributed together to the good performance for LIBs. It might open up a new way for application of silicon materials. [ABSTRACT FROM AUTHOR]