Preparation of Li4Ti5O12 Yolk–Shell Powders by Spray Pyrolysis and their Electrochemical Properties

We have reported for the first time the preparation of yolk–shell‐structured Li₄Ti₅O₁₂ powders for use as anode materials in lithium‐ion batteries. One Li₄Ti₅O₁₂ yolk–shell‐particle powder is directly formed from each droplet containing lithium, titanium, and carbon components inside the hot wall reactor maintained at 900 °C. The precursor Li₄Ti₅O₁₂ yolk–shell‐particle powders, which are directly prepared by spray pyrolysis, have initial discharge and charge capacities of 155 and 122 mA h g^?1, respectively, at a current density of 175 mA g^?1. Post‐treatment of the yolk–shell‐particle powders at temperatures of 700 and 800 °C improves the initial discharge and charge capacities. The initial discharge capacities of the Li₄Ti₅O₁₂ powders with a yolk–shell structure and a dense structure post‐treated at 800 °C are 189 and 168 mA h g^?1, respectively. After 100 cycles, the corresponding capacities are 172 and 152 mA h g^?1, respectively (retentions of 91 and 90 %).     

Low‐temperature Synthesis of Peony‐like Spinel Li4Ti5O12 as a High‐performance Anode Material for Lithium Ion Batteries

Peony‐like spinel Li₄Ti₅O₁₂ was synthesized via calcination of precursor at the temperature of 400°C, and the precursor was prepared through a hydrothermal process in which the reaction of hydrous titanium oxide with lithium hydroxide was conducted at 180°C. The as‐prepared product was investigated by SEM, TEM and XRD, respectively. As anode material for lithium ion battery, the Li₄Ti₅O₁₂ obtained was also characterized by galvanostatic tests and cyclic voltammetry measurements. It is found that the peony‐like Li₄Ti₅O₁₂ exhibited high rate capability of 119.7 mAh·g⁻¹ at 10 C and good capacity retention of 113.8 mAh·g⁻¹ after 100 cycles at 5 C, and these results indicate the peony‐like Li₄Ti₅O₁₂ has promising applications for lithium ion batteries with high performance.     

Li4Ti5O12 Nanoparticles Prepared with Gel-hydrothermal Process as a High Performance Anode Material for Li-ion Batteries

Li₄Ti₅O₁₂ (LTO) nanoparticles were prepared by gel‐hydrothermal process and subsequent calcination treatment. Calcination treatment led to structural water removal, decomposition of organics and primary formation of LTO. The formation temperature of spinel LTO nanoparticles was lower than that of bulk materials counterpart prepared by solid‐state reaction or by sol‐gel processing. Based on the thermal gravimetric analysis (TG) and differential thermal gravimetric (DTG), samples calcined at different temperatures (350, 500 and 700°C) were characterized by X‐ray diffraction (XRD), field emitting scanning electron microscopy (FESEM), transmission electron microscopy (TEM), cyclic voltammogram and charge‐discharge cycling tests. A phase transition during the calcination process was observed from the XRD patterns. And the sample calcined at 500°C had a distribution of diameters around 20 nm and exhibited large capacity and good high rate capability. The well reversible cyclic voltammetric results of both electrodes indicated enhanced electrochemical kinetics for lithium insertion. It was found that the Li₄Ti₅O₁₂ anode material prepared through gel‐hydrothermal process, when being cycled at 8 C, could preserve 76.6% of the capacity at 0.3 C. Meanwhile, the discharge capacity can reach up to 160.3 mAh·g^?1 even after 100 cycles at 1 C, close to the theoretical capacity of 175 mAh·g^?1. The gel‐hydrothermal method seemed to be a promising method to synthesize LTO nanoparticles with good application in lithium ion batteries and electrochemical cells.     

Synthesis of Mesoporous Lithium Titanate Thin Films and Monoliths as an Anode Material for High‐Rate Lithium‐Ion Batteries

Mesoporous Li₄Ti₅O₁₂ (LTO) thin film is an important anode material for lithium‐ion batteries (LIBs). Mesoporous films could be prepared by self‐assembly processes. A molten‐salt‐assisted self‐assembly (MASA) process is used to prepare mesoporous thin films of LTOs. Clear solutions of CTAB, P123, LiNO₃, HNO₃, and Ti(OC₄H₉)₄ in ethanol form gel‐like meso‐ordered films upon either spin or spray coating. In the assembly process, the CTAB/P123 molar ratio of 14 is required to accommodate enough salt species in the mesophase, in which the Li^I/P123 ratio can be varied between molar ratios of 28 and 72. Calcination of the meso‐ordered films produces transparent mesoporous spinel LTO films that are abbreviated as Cxx‐yyy‐zzz or CAxx‐yyy‐zzz (C=calcined, CA=calcined–annealed, xx=Li^I/P123 molar ratio, and yyy=calcination and zzz=annealing temperatures in Celsius) herein. All samples were characterized by using XRD, TEM, N₂‐sorption, and Raman techniques and it was found that, at all compositions, the LTO spinel phase formed with or without an anatase phase as an impurity. Electrochemical characterization of the films shows excellent performance at different current rates. The CA40‐350‐450 sample performs best among all samples tested, yielding an average discharge capacity of (176±1) mA h g^?1 at C/2 and (139±4) mA h g^?1 at 50 C and keeping 92 % of its initial discharge capacity upon 50 cycles at C/2.     

Steady-state polarization measurements of lithium insertion electrodes for high-power lithium-ion batteries

Steady-state polarization measurements of lithium titanium oxide (LTO; Li[Li_1/3Ti_5/3]O₄) were carried out using the 0-V lithium-ion cells consisting of two identical LTO-electrodes with a parallel-plate symmetrical electrode configuration. The sinusoidal voltage with the peak amplitude of 1.0 V was imposed at 0.1 Hz upon the 0-V cells and the current response was measured as a function of time. The steady-state polarization, obtained by plotting the current versus applied voltage, was linear in current up to approximately 60 mA cm^?2 or 4 A g^?1 based on the LTO weight and suggested the resistance polarization only for the lithium insertion electrode of the LTO. The method was also applied to lithium aluminum manganese oxide (LAMO; Li[Li_0.1Al_0.1Mn_1.8]O₄) and the resistance polarization of the LAMO-electrode was determined for currents up to approximately 25 mA cm^?2 or 2 A g^?1 based on the LAMO weight. The validity of the results was examined for the polarization measurements of the 2.5-V lithium-ion battery consisting of LTO and LAMO, and the significance of the polarization measurements of lithium insertion electrodes for high-power applications was discussed.     

Template‐Free Synthesis of Hierarchical Vanadium‐Glycolate Hollow Microspheres and Their Conversion to V2O5 with Improved Lithium Storage Capability

Nanosheet‐assembled hierarchical V₂O₅ hollow microspheres are successfully obtained from V‐glycolate precursor hollow microspheres, which in turn are synthesized by a simple template‐free solvothermal method. The structural evolution of the V‐glycolate hollow microspheres has been studied and explained by the inside‐out Ostwald‐ripening mechanism. The surface morphologies of the hollow microspheres can be controlled by varying the mixture solution and the solvothermal reaction time. After calcination in air, hierarchical V₂O₅ hollow microspheres with a high surface area of 70 m² g^?1 can be obtained and the structure is well preserved. When evaluated as cathode materials for lithium‐ion batteries, the as‐prepared hierarchical V₂O₅ hollow spheres deliver a specific discharge capacity of 144 mA h g^?1 at a current density of 100 mA g^?1, which is very close to the theoretical capacity (147 mA h g^?1) for one Li⁺ insertion per V₂O₅. In addition, excellent rate capability and cycling stability are observed, suggesting their promising use in lithium‐ion batteries.     

A Porous Mooncake-Shaped Li4Ti5O12 Anode Material Modified by SmF3 and Its Electrochemical Performance in Lithium Ion Batteries

Reasonably designing and synthesizing advanced electrode materials is significant to enhance the electrochemical performance of lithium ion batteries (LIBs). Herein, a metal–organic framework (MOF, Mil-125) was used as a precursor and template to successfully synthesize the porous mooncake-shaped Li₄Ti₅O₁₂ (LTO) anode material assembled from nanoparticles. Even more critical, SmF₃ was used to modify the prepared porous mooncake-shaped LTO material. The SmF₃-modified LTO maintained a porous mooncake-shaped structure with a large specific surface area, and the SmF₃ nanoparticles were observed to be attach on the surface of the LTO material. It has been proven that the SmF₃ modification can further facilitate the transition from Ti⁴⁺ to Ti³⁺, reduce the polarization of electrode, decrease charge transfer impedance (R_ct) and solid electrolyte interface impedance (R_sei), and increase the lithium ion diffusion coefficient (D_Li), thereby enhancing the electrochemical performance of LTO. Therefore, the porous mooncake-shaped LTO modified using 2 wt % SmF₃ displays a large specific discharge capacity of 143.8 mAh g⁻¹ with an increment of 79.16 % compared to pure LTO at a high rate of 10 C (1 C=170 mAh g⁻¹), and shows a high retention rate of 96.4 % after 500 cycles at 5 C-rate.     

One‐Step Pyro‐Synthesis of a Nanostructured Mn3O4/C Electrode with Long Cycle Stability for Rechargeable Lithium‐Ion Batteries

A nanostructured Mn₃O₄/C electrode was prepared by a one‐step polyol‐assisted pyro‐synthesis without any post‐heat treatments. The as‐prepared Mn₃O₄/C revealed nanostructured morphology comprised of secondary aggregates formed from carbon‐coated primary particles of average diameters ranging between 20 and 40 nm, as evidenced from the electron microscopy studies. The N₂ adsorption studies reveal a hierarchical porous feature in the nanostructured electrode. The nanostructured morphology appears to be related to the present rapid combustion strategy. The nanostructured porous Mn₃O₄/C electrode demonstrated impressive electrode properties with reversible capacities of 666 mAh g^?1 at a current density of 33 mA g^?1, good capacity retentions (1141 mAh g^?1 with 100 % Coulombic efficiencies at the 100^th cycle), and rate capabilities (307 and 202 mAh g^?1 at 528 and 1056 mA g^?1, respectively) when tested as an anode for lithium‐ion battery applications.     

Cu3V2O8 Nanoparticles as Intercalation‐Type Anode Material for Lithium‐Ion Batteries

Cu₃V₂O₈ nanoparticles with particle sizes of 40–50 nm have been prepared by the co‐precipitation method. The Cu₃V₂O₈ electrode delivers a discharge capacity of 462 mA h g^?1 for the first 10 cycles and then the specific capacity, surprisingly, increases to 773 mA h g^?1 after 50 cycles, possibly as a result of extra lithium interfacial storage through the reversible formation/decomposition of a solid electrolyte interface (SEI) film. In addition, the electrode shows good rate capability with discharge capacities of 218 mA h g^?1 under current densities of 1000 mA g^?1. Moreover, the lithium storage mechanism for Cu₃V₂O₈ nanoparticles is explained on the basis of ex situ X‐ray diffraction data and high‐resolution transmission electron microscopy analyses at different charge/discharge depths. It was evidenced that Cu₃V₂O₈ decomposes into copper metal and Li₃VO₄ on being initially discharged to 0.01 V, and the Li₃VO₄ is then likely to act as the host for lithium ions in subsequent cycles by means of the intercalation mechanism. Such an “in situ” compositing phenomenon during the electrochemical processes is novel and provides a very useful insight into the design of new anode materials for application in lithium‐ion batteries.     

Preparation and electrochemical performance of monodisperse Li4Ti5O12 hollow spheres

Monodisperse Li₄Ti₅O₁₂ hollow spheres were prepared by using carbon spheres as templates. Scanning electron microscopy images show hollow spheres that have an average outer diameter of 1.0 μm and an average wall thickness of 60 nm. Compared with Li₄Ti₅O₁₂ solids, the hollow spherical Li₄Ti₅O₁₂ exhibit an excellent rate capability and capacity retention and can be charged/discharged at 10 C (1.7 A g⁻¹) with a specific capacity of 100 mA h g⁻¹, and after 200 charge and discharge cycles at 2 C, their specific capacity remain very stable at 150 mA h g⁻¹. It is believed that the hollow structure has a relatively large contact surface between Li₄Ti₅O₁₂ and liquid electrolyte, resulting in a better electrochemical performance at high charge/discharge rate.     

Electrospun Li<Subscript>4</Subscript>Ti<Subscript>5</Subscript>O<Subscript>12</Subscript>/Li<Subscript>2</Subscript>TiO<Subscript>3</Subscript> composite nanofibers for enhanced high-rate lithium ion batteries

Li₄Ti₅O₁₂/Li₂TiO₃ composite nanofibers with the mean diameter of ca. 60 nm have been synthesized via facile electrospinning. When the molar ratio of Li to Ti is 4.8:5, the Li₄Ti₅O₁₂/Li₂TiO₃ composite nanofibers exhibit initial discharge capacity of 216.07 mAh g^?1 at 0.1 C, rate capability of 151 mAh g^?1 after being cycled at 20 C, and cycling stability of 122.93 mAh g^?1 after 1000 cycles at 20 C. Compared with pure Li₄Ti₅O₁₂ nanofibers and Li₂TiO₃ nanofibers, Li₄Ti₅O₁₂/Li₂TiO₃ composite nanofibers show better performance when used as anode materials for lithium ion batteries. The enhanced electrochemical performances are explained by the incorporation of appropriate Li₂TiO₃ which could strengthen the structure stability of the hosted materials and has fast Li⁺-conductor characteristics, and the nanostructure of nanofibers which could offer high specific area between the active materials and electrolyte and shorten diffusion paths for ionic transport and electronic conduction. Our new findings provide an effective synthetic way to produce high-performance Li₄Ti₅O₁₂ anodes for lithium rechargeable batteries.     

Graphitized carbon and graphene modified Fe2O3/Li4Ti5O12 as anode material for lithium ion batteries

Graphitized carbon (GC) and graphene (GE) modified Fe₂O₃/Li₄Ti₅O₁₂ (LTO) composites have been synthesized via a solid‐state reaction, respectively. The structure, morphology and electrochemical performance of the materials have also been characterized with X‐ray diffraction (XRD), scanning electron microscope (SEM) with an energy dispersive spectroscopy (EDS) system, X‐ray photoelectron spectrometer (XPS), Fourier transform infrared spectroscopy (FTIR) and electrochemical measurements. The discharge capacities of Fe₂O₃/LTO, GC/Fe₂O₃/LTO and GE/Fe₂O₃/LTO are 100.2 mAh g^?1, 207.5 mAh g^?1 and 238.9 mAh g^?1 after 100 cycles at the current density of 176 mA g^?1. The cyclic stability and rate capability are in the order of GE/Fe₂O₃/LTO > GC/Fe₂O₃/LTO > Fe₂O₃/LTO because of the synergistic effect between GC (GE) and Fe₂O₃/LTO. Copyright © 2016 John Wiley & Sons, Ltd.     

CNT@Fe3O4@C Coaxial Nanocables: One‐Pot,Additive‐Free Synthesis and Remarkable Lithium Storage Behavior

By using carbon nanotubes (CNTs) as a shape template and glucose as a carbon precursor and structure‐directing agent, CNT@Fe₃O₄@C porous core/sheath coaxial nanocables have been synthesized by a simple one‐pot hydrothermal process. Neither a surfactant/ligand nor a CNT pretreatment is needed in the synthetic process. A possible growth mechanism governing the formation of this nanostructure is discussed. When used as an anode material of lithium‐ion batteries, the CNT@Fe₃O₄@C nanocables show significantly enhanced cycling performance, high rate capability, and high Coulombic efficiency compared with pure Fe₂O₃ particles and Fe₃O₄/CNT composites. The CNT@Fe₃O₄@C nanocables deliver a reversible capacity of 1290 mA h g^?1 after 80 cycles at a current density of 200 mA g^?1, and maintain a reversible capacity of 690 mA h g^?1 after 200 cycles at a current density of 2000 mA g^?1. The improved lithium storage behavior can be attributed to the synergistic effect of the high electronic conductivity support and the inner CNT/outer carbon buffering matrix.     

One‐Pot Fabrication of Hierarchical Nanosheet‐Based TiO2–Carbon Hollow Microspheres for Anode Materials of High‐Rate Lithium‐Ion Batteries

Hierarchical and hollow nanostructures have recently attracted considerable attention because of their fantastic architectures and tunable property for facile lithium ion insertion and good cycling stability. In this study, a one‐pot and unusual carving protocol is demonstrated for engineering hollow structures with a porous shell. Hierarchical TiO₂ hollow spheres with nanosheet‐assembled shells (TiO₂ NHS) were synthesized by the sequestration between the titanium source and 2,2′‐bipyridine‐5,5′‐dicarboxylic acid, and kinetically controlled etching in trifluoroacetic acid medium. In addition, annealing such porous nanostructures presents the advantage of imparting carbon‐doped functional performance to its counterpart under different atmospheres. Such highly porous structures endow very large specifics surface area of 404 m² g^?1 and 336 m² g^?1 for the as‐prepared and calcination under nitrogen gas. C/TiO₂ NHS has high capacity of 204 mA h g^?1 at 1 C and a reversible capacity of 105 mA h g^?1 at a high rate of 20 C, and exhibits good cycling stability and superior rate capability as an anode material for lithium‐ion batteries.     

Supercritical Carbon Dioxide Assisted Deposition of Fe3O4 Nanoparticles on Hierarchical Porous Carbon and Their Lithium‐Storage Performance

A composite of highly dispersed Fe₃O₄ nanoparticles (NPs) anchored in three‐dimensional hierarchical porous carbon networks (Fe₃O₄/3DHPC) as an anode material for lithium‐ion batteries (LIBs) was prepared by means of a deposition technique assisted by a supercritical carbon dioxide (scCO₂)‐expanded ethanol solution. The as‐synthesized Fe₃O₄/3DHPC composite exhibits a bimodal porous 3D architecture with mutually connected 3.7 nm mesopores defined in the macroporous wall on which a layer of small and uniform Fe₃O₄ NPs was closely coated. As an anode material for LIBs, the Fe₃O₄/3DHPC composite with 79 wt % Fe₃O₄ (Fe₃O₄/3DHPC‐79) delivered a high reversible capacity of 1462 mA h g^?1 after 100 cycles at a current density of 100 mA g^?1, and maintained good high‐rate performance (728, 507, and 239 mA h g^?1 at 1, 2, and 5 C, respectively). Moreover, it showed excellent long‐term cycling performance at high current densities, 1 and 2 A g^?1. The enhanced lithium‐storage behavior can be attributed to the synergistic effect of the porous support and the homogeneous Fe₃O₄ NPs. More importantly, this straightforward, highly efficient, and green synthetic route will definitely enrich the methodologies for the fabrication of carbon‐based transition‐metal oxide composites, and provide great potential materials for additional applications in supercapacitors, sensors, and catalyses.     

Two‐Dimensional Cobalt‐/Nickel‐Based Oxide Nanosheets for High‐Performance Sodium and Lithium Storage

Two‐dimensional (2D) nanomaterials are one of the most promising types of candidates for energy‐storage applications due to confined thicknesses and high surface areas, which would play an essential role in enhanced reaction kinetics. Herein, a universal process that can be extended for scale up is developed to synthesise ultrathin cobalt‐/nickel‐based hydroxides and oxides. The sodium and lithium storage capabilities of Co₃O₄ nanosheets are evaluated in detail. For sodium storage, the Co₃O₄ nanosheets exhibit excellent rate capability (e.g., 179 mA h g^?1 at 7.0 A g^?1 and 150 mA h g^?1 at 10.0 A g^?1) and promising cycling performance (404 mA h g^?1 after 100 cycles at 0.1 A g^?1). Meanwhile, very impressive lithium storage performance is also achieved, which is maintained at 1029 mA h g^?1 after 100 cycles at 0.2 A g^?1. NiO and NiCo₂O₄ nanosheets are also successfully prepared through the same synthetic approach, and both deliver very encouraging lithium storage performances. In addition to rechargeable batteries, 2D cobalt‐/nickel‐based hydroxides and oxides are also anticipated to have great potential applications in supercapacitors, electrocatalysis and other energy‐storage‐/‐conversion‐related fields.     

Electochemical characteristics of LiMn<Subscript>2</Subscript>O<Subscript>4</Subscript>/Li<Subscript>4</Subscript>Ti<Subscript>5</Subscript>O<Subscript>12</Subscript> battery with conducting polymeric binder

Lithium-ion battery based on LiMn₂O₄/Li₄Ti₅O₁₂ materials was assembled for the first time. The cathode and anode of this battery are prepared with the aqueous combined binder poly-3,4-ethylenedioxythiophene: polystyrene sulfonate/carboxymethylcellulose (without polyvinylidene fluoride). The capacity of the LiMn₂O₄/Li₄Ti₅O₁₂ battery was found to be 75 mA h g^–1 at 0.1 C and 55 mA h g^–1 at 1 C. A 95% capacity was retained after 100 charge-discharge cycles. The batteries demonstrated a high Coulombic efficiency close to 100%. Scanning electron microscopy demonstrated that using the conducting binder poly-3,4-ethylenedioxythiophene: polystyrene sulfonate/carboxymethylcellulose provides formation of dense compact layers of electrode materials with good adhesion to the substrate. The electrode structure remains maintained after 100 charge-discharge cycles.     

Self‐Assembling Synthesis of Free‐standing Nanoporous Graphene–Transition‐Metal Oxide Flexible Electrodes for High‐Performance Lithium‐Ion Batteries and Supercapacitors

The synthesis of nanoporous graphene by a convenient carbon nanofiber assisted self‐assembly approach is reported. Porous structures with large pore volumes, high surface areas, and well‐controlled pore sizes were achieved by employing spherical silica as hard templates with different diameters. Through a general wet‐immersion method, transition‐metal oxide (Fe₃O₄, Co₃O₄, NiO) nanocrystals can be easily loaded into nanoporous graphene papers to form three‐dimensional flexible nanoarchitectures. When directly applied as electrodes in lithium‐ion batteries and supercapacitors, the materials exhibited superior electrochemical performances, including an ultra‐high specific capacity, an extended long cycle life, and a high rate capability. In particular, nanoporous Fe₃O₄–graphene composites can deliver a reversible specific capacity of 1427.5 mAh g^?1 at a high current density of 1000 mA g^?1 as anode materials in lithium‐ion batteries. Furthermore, nanoporous Co₃O₄–graphene composites achieved a high supercapacitance of 424.2 F g^?1. This work demonstrated that the as‐developed freestanding nanoporous graphene papers could have significant potential for energy storage and conversion applications.     

Ab initio Studies on Li4+xTi5O12 Compounds as Anode Materials for Lithium‐Ion Batteries

The structural and electronic properties of Li_4+xTi₅O₁₂ compounds (with 0≤x≤6)—to be used as anode materials for lithium‐ion batteries—are studied by means of first principles calculations. The results suggest that Li₄Ti₅O₁₂ can be lithiated to the state Li_8.5Ti₅O₁₂, which provides a theoretical capacity that is about 1.5 times higher than that of the compound lithiated to Li₇Ti₅O₁₂. Further insertion of lithium species into the Li_8.5Ti₅O₁₂ lattice results in a clear structural distortion. The small lattice expansion observed upon lithium insertion (about 0.4 % for the lithiated material Li_8.5Ti₅O₁₂) and the retained [Li₁Ti₅]^16dO₁₂ framework indicate that the insertion/extraction process is reversible. Furthermore, the predicted intercalation potentials are 1.48 and 0.05 V (vs Li/Li⁺) for the Li₄Ti₅O₁₂/Li₇Ti₅O₁₂ and Li₇Ti₅O₁₂/Li_8.5Ti₅O₁₂ composition ranges, respectively. Electronic‐structure analysis shows that the lithiated states Li_4+xTi₅O₁₂ are metallic, which is indicative of good electronic‐conduction properties.     

Wintersweet‐Flower‐Like CoFe2O4/MWCNTs Hybrid Material for High‐Capacity Reversible Lithium Storage

CoFe₂O₄/multiwalled carbon nanotubes (MWCNTs) hybrid materials were synthesized by a hydrothermal method. Field emission scanning electron microscopy and transmission electron microscopy analysis confirmed the morphology of the as‐prepared hybrid material resembling wintersweet flower “buds on branches”, in which CoFe₂O₄ nanoclusters, consisting of nanocrystals with a size of 5–10 nm, are anchored along carbon nanotubes. When applied as an anode material in lithium ion batteries, the CoFe₂O₄/MWCNTs hybrid material exhibited a high performance for reversible lithium storage. In particular, the hybrid anode material delivered reversible lithium storage capacities of 809, 765, 539, and 359 mA h g^?1 at current densities of 180, 450, 900, and 1800 mA g^?1, respectively. The superior performance of CoFe₂O₄/MWCNTs hybrid materials could be ascribed to the synergistic pinning effect of the wintersweet‐flower‐like nanoarchitecture. This strategy could also be applied to synthesize other metal oxide/CNTs hybrid materials as high‐capacity anode materials for lithium ion batteries.