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Fe 2 O 3 nanorods are synthesized by combustion method using alcohol as both solvent and fuel, which is a facile and effective strategy for the large-scale and inexpensive fabrication. The Fe 2 O 3 nanorods are with the well distributed diameters of 20–30 nm and length ranging from 80 to 100 nm. As an anode material for lithium-ion batteries, the Fe 2 O 3 nanorod electrode delivers a high discharge capacity of 761.7 mA h g −1 after 60 cycles at 500 mA g −1 , and 727.2 mA h g −1 at a high current density of 2000 mA g −1 . The good electrochemical performance is attributed to the sufficient contact of active material and electrolyte, large surface area, and short diffusion length of Li + .

Novel Li1.2Mn0.5Co0.25Ni0.05O2 microcube is prepared through a simple binary template method. After calcined at 800 °C, lithium and nickel are permeated into the cathode material and a well-crystallized Li-rich layered oxide is obtained. Furthermore, hollow circle cube architecture is formed due to the decomposing of the carbonate. As a cathode material for lithium ion batteries (LIBs), the oxide with such architecture can deliver high initial discharge capacity of 272.9 mAh g−1 at a current density of 20 mA g−1. High reversible discharge capacities of 208 mAh g−1 and 110 mAh g−1 are obtained at a current density of 200 mA g−1 and 2000 mA g−1, respectively. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) are performed to further study the hollow Li1.2Mn0.5Co0.25Ni0.05O2 microcube. It is remarkable that such architecture makes the Li-rich layered oxide Li1.2Mn0.5Co0.25Ni0.05O2 a promising cathode material for LIBs.

CoFe2O4 flower-like microspheres are prepared via a surfactant- and template-free method, involving the controlled hytrothermal synthesis firstly and a subsequent thermal decomposition treatment. The microspheres with diameters of 3–4 μm are characterized by the assembly of numerous porous and inter-connected lamella structures. Lithium-ion batteries electrodes based on the as-prepared CoFe2O4 microspheres show a high specific capacity of 733.5 mAh g−1 after 50 cycles at a current density of 200 mA g−1 and a good cyclic stability, as well as excellent rate capability. The enhanced electrochemical performance can be attributed to the hierarchical microsphere structure with high sufficient interfacial contact area between the microspheres and electrolyte, the short diffusion distance of Li+, better accommodation of structural stress and volume change with the lithiation/delithiation process. It is suggested that the CoFe2O4 microsphere is one of the most promising candidates for high-performance lithium-ion batteries.

Surface modified-LiV 3 O 8 cathode materials with Al 2 O 3 are successfully synthesized via a facile thermolysis process. The 0.5 wt.% Al 2 O 3 -coated LiV 3 O 8 exhibits an enhanced cyclic stability at various charge–discharge current densities. At a current density of 100 mA g −1 , it delivers an initial specific discharge capacity of 283.1 mAh g −1 between 2.0 and 4.0 V. Moreover, high capacities of 139.4 and 118.5 mAh g −1 are obtained at the 100th cycle at current densities of 2000 and 3000 mA g −1 , respectively. The improved electrochemical performance is attributed to the Al 2 O 3 coating, which can hinder the irreversible phase transformation and act as a protective layer to prevent the active material from direct contact with electrolyte. Furthermore, the formation of a Li–V–Al–O solid solution at the LiV 3 O 8 /Al 2 O 3 interface provides a fast Li + diffusion path which is of benefit to the electrochemical behaviors.

LiVO3 materials are synthesized by combustion method with oxalic acid as fuel. Owing to its relatively low crystallization and small particle size, the LiVO3 calcined at 450 °C for 2 h displays optimal electrochemical performances, delivering a high discharge capacity of 298.4 mAh g−1 and 262.5 mAh g−1 between 1.0 and 3.5 V at a current density of 50 mA g−1 and 500 mA g−1 respectively, and exhibiting good cyclic stability. In this work, the chemical diffusion coefficient of Li+ (DLi+) in the LiVO3 electrode is determined by electrochemical impedance spectroscopy (EIS) and galvanostatic intermittent titration technique (GITT). The value calculated by EIS is in the range of 10−9–10−8 cm2 s−1, while it calculated by GITT is 10−9.5–10−8 cm2 s−1.

One-dimension MnCo 2 O 4 nanowire arrays are synthesized on nickel foam by a facile hydrothermal method. The MnCo 2 O 4 nanowires are highly crystalline with an average diameter of 70 nm and exhibit excellent properties for electrochemical energy storage. Impressively, the MnCo 2 O 4 nanowire array exhibits noticeable pseudocapacitive performance with a high capacitance of 349.8 F g −1 at 1 A g −1 and 328.9 F g −1 at 20 A g −1 as well as excellent cycling stability. As an anode material for Li-ion batteries, the MnCo 2 O 4 nanowire array delivers an initial specific discharge capacity of 1288.6 mAh g −1 at 100 mA g −1 , with reversible capacity retention of 92.7% after 50 cycles. The outstanding electrochemical performances are mainly attributed to its nanowire array architecture which provides large reaction surface area, fast ion and electron transfer and good structure stability.

Cube-like and plate-like Li[Li 0.2 Mn 0.54 Ni 0.13 Co 0.13 ]O 2 particles are obtained after treated in LiCl and KCl molten salts at 800 °C, respectively, comparing to the ball-like original particles calcined in air. The oxide treated in KCl molten salt with large specific area of 17.05 m 2 g −1 delivers high discharge capacities of 254.1 mAh g −1 and 168.5 mAh g −1 at current densities of 200 mA g −1 and 2000 mA g −1 , respectively. In addition, enhanced cycle stability with capacity retention of 94.9% after 80 cycles at charge–discharge current densities of 200 mA g −1 is obtained for the oxide treated in LiCl molten salt with sacrifice of a little capacity. Such electrochemical performance change is proved to be independent of Li + diffusion coefficient. It appears that the treatment in molten salts can effectively reform the electrochemical performances of Li[Li 0.2 Mn 0.54 Ni 0.13 Co 0.13 ]O 2 cathode materials for various applications.

Macroporous Li1.2Mn0.54Ni0.13Co0.13O2 cathode materials with high crystallinity and hexagonal ordering are synthesized by aerogel template followed by solid state reaction. High discharge capacities of 244.0 mA h g−1 and 153.9 mA h g−1 are obtained for the Li-rich layered oxide synthesized at 800 °C at current densities of 200 mA g−1 and 2000 mA g−1 between 2.0 V and 4.8 V. Increasing the synthesis temperature to 900 °C, the macroporous Li1.2Mn0.54Ni0.13Co0.13O2 delivers a high discharge capacity of 220.2 mA h g−1 at a current density of 200 mA g−1 with a capacity retention of 89.1% after 50 cycles, 129.8 mA h g−1 at a current density of 2000 mA g−1 and almost no capacity fading after 120 cycles. The diffusion coefficients of Li+ in the Li-rich layered oxide determined by galvanostatic intermittent titration technique are in the range of 5.0 × 10−18−8.0 × 10−14 cm2 s−1. Electrochemical impedance spectroscopy indicates that the macroporous structure with good particle contact of the layered oxide can improve its rate capability and cyclic stability.

Li-rich layered oxide Li[Li0.2Mn0.54Ni0.13Co0.13]O2 is synthesized by combustion reaction using alcohol as both solvent and fuel. X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) show that the oxide synthesized at 800 °C exhibits perfect crystallinity and lattice ordering, and has particle sizes of 50–150 nm. The layered oxide delivers an initial discharge capacity of 290.1 mAh g−1 at a current density of 20 mA g−1 after activation, and exhibits improved rate capability with high discharge capacities of 238.6 and 165.0 mAh g−1 at current densities of 200 and 2000 mA g−1 in the voltage range of 2.0–4.8 V, respectively. Low Li-ion diffusion coefficient of 1.07 × 10−14−1.01 × 10−16 cm2 s−1 is calculated by galvanostatic intermittent titration technique (GITT) during the initial discharge process, indicating that the improved rate capability is mainly attributed to the small particle sizes of the Li-rich oxide.

A unique cobalt nanomountain array supported Si film was successfully fabricated by the combination of electrodeposition and radiofrequency magnetron sputtering. The nanostructured Si film with a proper thickness shows excellent cyclic performance with a high discharge capacity of 1917.8 mAh g −1 after 100 cycles at 0.1 C, also presents high rate capability with revisable capacities of 1953.3 mAh g −1 at 0.5 C and 1166.1 mAh g −1 at 3 C. The improved electrochemical performance can be attributed to the strengthening adhesion of the Si film to the cobalt nanomountain arrays and the formation of an island structure within the film, which provide good mechanical support and electron conducting pathway. The well-designed nanostructured Si electrode is a promising material for application of lithium ion batteries.

MgO-coated Li[Li 0.2 Mn 0.54 Ni 0.13 Co 0.13 ]O 2 was synthesized via melting impregnation method followed by a solid state reaction. Transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) show that the MgO layer is well coated on the surface of the layered oxide particles. Although the initial discharge capacity of Li[Li 0.2 Mn 0.54 Ni 0.13 Co 0.13 ]O 2 with proper MgO modification decreases compared to the bare one, the 2 wt.% MgO coated cathode exhibits the excellent cycling stability with capacity retention of 96.4% at a current density of 200 mA g −1 after 100 cycles at room temperature and 94.3% after 50 cycles at 60 °C. Electrochemical impedance spectroscopy (EIS) shows that the thin MgO layer mainly reduces the charge transfer resistance and stabilizes the surface structure of active material during cycling. Melting impregnation method is promising for MgO coating to improving the cycling stability of Li-rich layered oxide cathode for Li-ion batteries.

Well-formed Li 1.131 Mn 0.504 Ni 0.243 Co 0.122 O 2 cathode materials are synthesized via freeze drying followed by a solid state reaction at temperatures of 750–900 °C. Among these oxides, the one synthesized at 800 °C delivers the highest initial discharge capacity of 246.5 mAh g −1 at 0.1 C (1 C = 200 mA g −1 ) between 2.5 V and 4.8 V. Enhancing the discharge rate to 1 C, initial capacity of 197.8 mAh g −1 is obtained, and 78.8% capacity is retained after 50 cycles. Furthermore, the diffusion coefficients of Li + in the lithium-rich layered oxide are about 10 −14 cm 2 s −1 and 10 −15 cm 2 s −1 for the initial charge platform at 3.90 V and 4.55 V, respectively, determined by galvanostatic intermittent titration technique (GITT). The Li 1.131 Mn 0.504 Ni 0.243 Co 0.122 O 2 prepared by freeze drying is a promising cathode material for lithium ion batteries.

CaF 2 -coated LiMn 1/3 Ni 1/3 Co 1/3 O 2 cathode material is prepared via a wet chemical process followed by a solid state reaction. High-resolution transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) show that the well coated CaF 2 layer has a thickness of 4–8 nm, and no interaction of chemical bonding is observed. The CaF 2 -coated LiMn 1/3 Ni 1/3 Co 1/3 O 2 exhibits discharge capacity retention of 98.1% at 0.1 C after 50 cycles and high initial discharge capacity of 146.3 mAh g −1 at 5 C. Furthermore, even at an elevated charge–discharge rate of 5 C, capacity retention maintains above 85%. Electrochemical impedance spectroscopy (EIS) shows that the CaF 2 coating can stabilize the surface structure and reduce the charge transfer resistance. The CaF 2 modification has a promising application in improving the performance of layered oxide cathode materials for Li-ion batteries.

We report a silicon/graphene-sheet hybrid film prepared by combining electrophoretic deposition and radiofrequency magnetron deposition methods. The constructed hybrid film shows rough morphology with wrinkles and scrolling edges. As anode material for lithium ion batteries, the silicon/graphene-sheet hybrid film exhibits enhanced electrochemical performances with weaker polarization, higher capacity, better rate capability and cycling performance as compared to the bare silicon film. The silicon/graphene-sheet hybrid film delivers a high initial reversible capacity of 2204 mAh g−1 and quite good cycling life (capacity maintenance is 87.7%) after 150 cycles. The graphene-sheet in the hybrid film is responsible for the improvement of the electrochemical properties. The introduction of the graphene-sheet film not only enhances the adhesion between silicon and the current collector, but also alleviates the structure degradation caused by volume expansion and the shrinkage of silicon film during lithium-ion insertion/extraction, resulting in improved electrochemical performances. Keywords: Silicon, Graphene, Lithium ion battery, Magnetron sputtering

A three-dimensional (3D) porous nano-Ni supported Si composite film is successfully fabricated by the combination of hydrogen bubble template electrodeposition of porous nano-Ni film and radiofrequency magnetron sputtering amorphous silicon. As anode for lithium-ion batteries, the 3D porous Ni/Si composite film shows noticeable electrochemical performance with high capacity of 2444 mAh g −1 at a current density of 0.84 A g −1 , superior capacity retention of 83% after 100 cycles, as well as excellent rate capability with 1420 and 1273 mAh g −1 at charge–discharge current densities of 4.2 A g −1 and 8.4 A g −1 after 100 cycles, respectively. The enhanced electrochemical performance is mainly attributed to the highly porous conductive architecture, which provides good mechanical support and electron conducting pathway for active silicon and alleviates the structure degradation caused by volume expansion during the cycling process.

Carbon-coated layered oxide Li 1.048 Mn 0.381 Ni 0.286 Co 0.286 O 2 is prepared by combining a co-precipitation and a direct current magnetron sputtering. TEM images show that the carbon layer is relatively well coated on the surface of oxide particles. The Li 1.048 Mn 0.381 Ni 0.286 Co 0.286 O 2 /C composite delivers an initial discharge capacity of 203.2 mAh g −1 between 2.5 and 4.5 V at 0.1 C, and 94% of the initial discharge capacity can be retained after 100 cycles. Moreover, the carbon-coated oxide exhibits noticeable high-rate capacity of 145 mAh g −1 at 5 C, much higher than the pristine one (103 mAh g −1 at 5 C). The improved discharge capacity and cycle performance are attributed to the carbon coating, which protects the Li-rich cathode material from reacting with the electrolyte and retarding the incrassation of SEI film on the surface of oxide particles.

Li 3 V 2 (PO 4 ) 3 , Li 3 V 2 (PO 4 ) 3 /C and Li 3 V 2 (PO 4 ) 3 /(Ag + C) composites as cathodes for Li ion batteries are synthesized by carbon-thermal reduction (CTR) method and chemical plating reactions. The microstructure and morphology of the compounds are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The Li 3 V 2 (PO 4 ) 3 /(Ag + C) particles are 0.5–1 μm in diameters. As compared to Li 3 V 2 (PO 4 ) 3 , Li 3 V 2 (PO 4 ) 3 /C, the Li 3 V 2 (PO 4 ) 3 /(Ag + C) composite cathode exhibits high discharge capacity, good cycle performance (140.5 mAh g −1 at 50th cycle at 1 C, 97.3% of initial discharge capacity) and rate behavior (120.5 mAh g −1 for initial discharge at 5 C) for the fully delithiated (3.0–4.8 V) state. Electrochemical impedance spectroscopy (EIS) measurements show that the carbon and silver co-modification decreases the charge transfer resistance of Li 3 V 2 (PO 4 ) 3 /(Ag + C) cathode, and improves the conductivity and boosts the electrochemical performance of the electrode.

Highly ordered porous Cu 2 O film is electrodeposited on copper foil through a self-assembled polystyrene sphere template. Compared with the dense Cu 2 O film and the octahedral Cu 2 O powder, the ordered porous Cu 2 O film exhibits an improved electrochemical cycling stability. The capacity of the porous Cu 2 O film can maintain 336 mAh g −1 and 213 mAh g −1 after 50 cycles at the rate of 0.1 C and 5 C, respectively. The reversible capacity holds 63.4% as the discharge–charge rate even increases by 50 times. The enhanced high rate properties of the ordered porous film should be attributed to the sufficient contact surface of Cu 2 O/electrolyte and the short diffusion length of Li + . Moreover, the direct contact between Cu 2 O and current collector and the decreasing inactive interfaces of Cu 2 O/polymer binder are also suggested as being responsible for the enhanced high rate property.

Hierarchical, nanostructured copper oxide spheres were synthesized in a stirred solution of cupric acetate and ammonium hydroxide. Cetyltrimethylammonium bromide (CTAB) was used as a surfactant to modify the surface morphology of CuO spheres. Ordered nano-needle arrays can be formed on the surface of the CuO spheres (instead of disordered nano-leaves) in the presence of CTAB. Each CuO sphere is about 2 μm in diameter and possesses a large number of nano-needles that are about 20–40 nm in width and more than 300 nm in length. The needle-like hierarchical structure can greatly increase the contact area between CuO and electrolyte, which provides more sites for Li+ accommodation, shortens the diffusion length of Li+ and enhances the reactivity of electrode reaction, especially at high rates. After 50 cycles, the reversible capacity of the prepared needle-like CuO can sustain 62.4% and 56.4% of the 2nd cycle at a rate of 0.1C and 1C, respectively.

We report a simple self-assembled synthesis of hierarchical CuO particles with various morphologies such as leaf, shuttle, flower, dandelion, and caddice clew. The morphologies can be easily tailored by adjusting the pH value. The synthesis is based on dehydration and re-crystallization of precursor Cu(OH) 2 nanowires. [Cu(NH 3 ) 4 ] 2+ and OH − in the solutions are considered as the key factors to influence the assembling manner of CuO. The obtained hierarchical CuO particles serve as a good model system for the study as anodes for lithium ion batteries. Various morphologies of CuO particles result in different electrochemical performances of electrodes. Compared to others, dandelion-like and caddice clew-like CuO exhibit reversible discharge capacities of 385 mAh g −1 and 400 mAh g −1 at 0.1 C, 340 mAh g −1 and 374 mAh g −1 at 0.5 C after 50 cycles, respectively. The higher discharge capacities and better cycling performances are attributed to their larger surface area and porosity, leading to better contact between CuO and electrolyte and shorter diffusion length of lithium ions.