Spindle-like Mesoporous α-Fe(2)O(3) Anode Material Prepared from MOF Template for High-Rate Lithium Batteries

Spindle-like porous α-Fe(2)O(3) was prepared from an iron-based metal organic framework (MOF) template. When tested as anode material for lithium batteries (LBs), this spindle-like porous α-Fe(2)O(3) shows greatly enhanced performance of Li storage. The particle with a length and width of ～0.8 and ～0.4 μm, respectively, was composed of clustered Fe(2)O(3) nanoparticles with sizes of <20 nm. The capacity of the porous α-Fe(2)O(3) retained 911 mAh g(-1) after 50 cycles at a rate of 0.2 C. Even when cycled at 10 C, comparable capacity of 424 mAh g(-1) could be achieved.     

锂离子电池正极材料LiMn_2O_4制备新工艺

采用球磨湿混和旋转合成相结合的新工艺来制备锂离子电池正极材料ＬｉＭｎ２Ｏ４,并对制备的材料进行了粒度、化学成分以及电化学性能测试．制备的ＬｉＭｎ２Ｏ４为正尖晶石结构,而且物质纯净．同一批次制备的材料化学成分均匀,粉末粒度分布范围窄,中粒径为１０．６７μｍ,首次充电容量为１２４ｍＡｈ／ｇ,放电容量为１１５ｍＡｈ／ｇ．循环次数达３０次时,放电容量还大于１００ｍＡｈ／ｇ,循环稳定性良好．球磨湿混工艺能将原料混合均匀,并能有效地使原料粒度细化而且粒度均匀．旋转合成工艺能使反应物和反应产物的温度均匀、粒度均匀、晶型结构与成分均匀．球磨湿混和旋转合成相结合的固相合成新工艺能制备出电化学性能性能良好的ＬｉＭｎ２Ｏ４     

Hierarchical three-dimensional ZnCo₂O₄ nanowire arrays/carbon cloth anodes for a novel class of high-performance flexible lithium-ion batteries

Flexible electronics is an emerging and promising technology for next generation of optoelectronic devices. Herein, hierarchical three-dimensional ZnCo(2)O(4) nanowire arrays/carbon cloth composites were synthesized as high performance binder-free anodes for Li-ion battery with the features of high reversible capacity of 1300-1400 mAh g(-1) and excellent cycling ability even after 160 cycles with a capacity of 1200 mAh g(-1). Highly flexible full batteries were also fabricated, exhibiting high flexibility, excellent electrical stability, and superior electrochemical performances.     

Large reversible Li storage of graphene nanosheet families for use in rechargeable lithium ion batteries

The lithium storage properties of graphene nanosheet (GNS) materials as high capacity anode materials for rechargeable lithium secondary batteries (LIB) were investigated. Graphite is a practical anode material used for LIB, because of its capability for reversible lithium ion intercalation in the layered crystals, and the structural similarities of GNS to graphite may provide another type of intercalation anode compound. While the accommodation of lithium in these layered compounds is influenced by the layer spacing between the graphene nanosheets, control of the intergraphene sheet distance through interacting molecules such as carbon nanotubes (CNT) or fullerenes (C60) might be crucial for enhancement of the storage capacity. The specific capacity of GNS was found to be 540 mAh/g, which is much larger than that of graphite, and this was increased up to 730 mAh/g and 784 mAh/g, respectively, by the incorporation of macromolecules of CNT and C60 to the GNS.     

Fe(3)O(4) nanobelts: one-pot and template-free synthesis, magnetic property, and application for lithium storage

We report on the synthesis of Fe(3)O(4) nanobelts with good magnetic properties and lithium storage performances by using a one-pot and template-free hydrothermal method with Na(2)CO(3) and FeCl(2) as the reactants. By controlling the amount of Na(2)CO(3), we obtained pure Fe(3)O(4) nanobelts with widths of 0.1-2?μm, thicknesses of about 10 nm and lengths of 20-30?μm, showing a high aspect ratio. XRD and SAED patterns of the obtained sample demonstrated that the Fe(3)O(4) nanobelts were well crystallized. Nitrogen adsorption/desorption measurements showed that Fe(3)O(4) nanobelts manifested a BET surface area of 25.04?m(2)?g(-1). Further experiments demonstrated that the amount of Na(2)CO(3) played an important role in controlling both the morphologies and crystal structures of the products. The formation mechanism of Fe(3)O(4) nanobelts was also studied. More importantly, we found that the Fe(3)O(4) nanobelts showed magnetic properties with a magnetic saturation value of 77.0?emu?g(-1) and lithium storage performances with a high initial discharge capacity of 1090?mAh?g(-1) at a current rate of 500?mA?g(-1), and a reversible capacity of 404?mAh?g(-1) retained after 60 charge/discharge cycles. These results suggest that the Fe(3)O(4) nanobelts might be promising for magnetic and lithium battery applications.     

Hollow iron oxide nanoparticles for application in lithium ion batteries

Material design in terms of their morphologies other than solid nanoparticles can lead to more advanced properties. At the example of iron oxide, we explored the electrochemical properties of hollow nanoparticles with an application as a cathode and anode. Such nanoparticles contain very high concentration of cation vacancies that can be efficiently utilized for reversible Li ion intercalation without structural change. Cycling in high voltage range results in high capacity (～132 mAh/g at 2.5 V), 99.7% Coulombic efficiency, superior rate performance (133 mAh/g at 3000 mA/g) and excellent stability (no fading at fast rate during more than 500 cycles). Cation vacancies in hollow iron oxide nanoparticles are also found to be responsible for the enhanced capacity in the conversion reactions. We monitored in situ structural transformation of hollow iron oxide nanoparticles by synchrotron X-ray absorption and diffraction techniques that provided us clear understanding of the lithium intercalation processes during electrochemical cycling.     

碳包覆空心Fe3O4纳米粒子作为锂离子电池负极材料的电化学性能研究

以二茂铁为铁源,石油渣油为碳源,通过加压热解和空气氧化制备了碳包覆空心Fe3O4纳米粒子。采用X射线衍射(XRD)、透射电镜(TEM)以及高倍透射电镜(HRTEM)等测试方法对样品的形貌和结构进行表征。采用恒流充放电和交流阻抗方法测试碳包覆空心Fe3O4纳米粒子作为锂离子电池负极材料的电化学性能。在电流密度为0.2mA/cm2时,首次放电比容量高达1294.7mAh/g,30次循环之后其放电比容量为392.1mAh/g;电流密度为1mA/cm2时,首次放电比容量为216.3mAh/g,30次循环之后其放电比容量为113mAh/g。     

Synthesis of nitrogen-doped MnO/graphene nanosheets hybrid material for lithium ion batteries

Nitrogen-doped MnO/graphene nanosheets (N-MnO/GNS) hybrid material was synthesized by a simple hydrothermal method followed by ammonia annealing. The samples were systematically investigated by X-ray diffraction analysis, Raman spectroscopy, X-ray photoelectron spectroscopy, transmission electron microscopy, and atomic force microscopy. N-doped MnO (N-MnO) nanoparticles were homogenously anchored on the thin layers of N-doped GNS (N-GNS) to form an efficient electronic/ionic mixed conducting network. This nanostructured hybrid exhibited a reversible electrochemical lithium storage capacity as high as 772 mAh g(-1) at 100 mA g(-1) after 90 cycles, and an excellent rate capability of 202 mA h g(-1) at a high current density of 5 A g(-1). It is expected that N-MnO/GNS hybrid could be a promising candidate material as a high capacity anode for lithium ion batteries.     

High‐Lithium‐Affinity Chemically Exfoliated 2D Covalent Organic Frameworks

Covalent organic frameworks (COFs) with reversible redox behaviors are potential electrode materials for lithium‐ion batteries (LIBs). However, the sluggish lithium diffusion kinetics, poor electronic conductivity, low reversible capacities, and poor rate performance for most reported COF materials limit their further application. Herein, a new 2D COF (TFPB‐COF) with six unsaturated benzene rings per repeating unit and ordered mesoporous pores (≈2.1 nm) is designed. A chemical stripping strategy is developed to obtain exfoliated few‐layered COF nanosheets (E‐TFPB‐COF), whose restacking is prevented by the in situ formed MnO₂ nanoparticles. Compared with the bulk TFPB‐COF, the exfoliated TFPB‐COF exhibits new active Li‐storage sites associated with conjugated aromatic π electrons by facilitating faster ion/electron kinetics. The E‐TFPB‐COF/MnO₂ and E‐TFPB‐COF electrodes exhibit large reversible capacities of 1359 and 968 mAh g^?1 after 300 cycles with good high‐rate capability.     

锂离子电池多孔硅/碳复合负极材料的研究

以商业化多晶硅粉为原料, 采用金属银催化剂诱导化学腐蚀的方法制得三维多孔硅材料。通过优化腐蚀条件, 得到孔径约为130 nm, 比表面为4.85 m²/g的多孔硅材料。将多孔硅和PAN溶液混合球磨并经高温烧结后在多孔硅表面包覆上一层致密的无定形碳膜, 从而制得多孔硅/碳复合材料作为锂离子电池的负极材料。3D多孔硅结构可以缓解电化学嵌/脱锂过程中材料的体积效应, 无定形碳膜层可有效改善复合材料的导电性能。电化学性能测试表明, 该多孔硅/碳复合负极材料电池在0.4 A/g的恒电流下, 首次放电容量3345 mAh/g, 首次循环库伦效率85.8%, 循环55次后容量仍保持有1645 mAh/g。并且在4 A/g的倍率下, 容量仍维持有1174 mAh/g。该方法原料成本低廉, 可规模化生产。     

Nitrogen-doped multiwall carbon nanotubes for lithium storage with extremely high capacity

The increasing demands on high performance energy storage systems have raised a new class of devices, so-called lithium ion capacitors (LICs). As its name says, LIC is an intermediate system between lithium ion batteries and supercapacitors, designed for taking advantages of both types of energy storage systems. Herein, as a quest to improve the Li storage capability compared to that of other existing carbon nanomaterials, we have developed extrinsically defective multiwall carbon nanotubes by nitrogen-doping. Nitrogen-doped carbon nanotubes contain wall defects through which lithium ions can diffuse so as to occupy a large portion of the interwall space as storage regions. Furthermore, when integrated with 3 nm nickel oxide nanoparticles for a further capacity boost, nitrogen doping enables unprecedented cell performance by engaging anomalous electrochemical phenomena such as nanoparticles division into even smaller ones, their agglomeration-free diffusion between nitrogen-doped sites as well as capacity rise with cycles. The final cells exhibit a capacity as high as 3500 mAh/g, a cycle life of greater than 10,000 times, and a discharge rate capability of 1.5 min while retaining a capacity of 350 mAh/g.     

三维网络结构氧化铜纳米线锂离子电池负极材料的制备和性能研究

通过阳极氧化法和后退火处理在铜箔上合成了三维网络结构氧化铜纳米线,将其作为负极材料制备了无需添加粘结剂的锂离子电池。研究了恒压氧化时间对材料形貌和电化学性能的影响。在1C的倍率下,氧化1000 s制备的CuO纳米线表现出最高的1172 mAh/g首圈放电比容量和594 mAh/g的可逆比容量,500圈循环可逆比容量为607.6 mAh/g,可逆容量保留率为102.3%。交联的三维网络结构CuO纳米线相互支撑,提供稳定的结构,有效缓解了CuO纳米线作为锂离子电池负极材料中的体积膨胀问题,表现出了优异的倍率性能和循环寿命。     

Layered Li0.88[Li0.18Co0.33Mn0.49]O2 nanowires for fast and high capacity Li-Ion storage material

Layered Li0.88[Li0.18Co0.33Mn0.49]O2 nanowires are prepared using Co0.4Mn0.6O2 nanowires and lithium nitrate as precursors at 200 degrees C via a hydrothermal method for fast and high capacity Li-ion storage material. The obtained nanowires exhibit a reversible capacity of 230 mAh/g between 2 and 4.8 V, even at the high current rate of 3600 mA/g.     

Three-dimensional graphene membrane cathode for high energy density rechargeable lithium-air batteries in ambient conditions

Lithium-air batteries have attracted significant interest for applications in high energy density mobile power supplies,yet there are considerable challenges to the development of rechargeable Li-air batteries with stable cycling performance under ambient conditions.Here we report a three-dimensional (3D) hydrophobic graphene membrane as a moisture-resistive cathode for high performance Li-air batteries.The 3D graphene membrane features a highly interconnected graphene network for efficient charge transport,a highly porous structure for efficient diffusion of oxygen and electrolyte ions,a large specific surface area for high capacity storage of the insulating discharge product,and a network of highly tortuous hydrophobic channels for O2/H2O selectivity.These channels facilitate O2 ingression while retarding moisture diffusion and ensure excellent charge/discharge cycling stability under ambient conditions.The membrane can thus enable robust Li-air batteries with exceptional performance,including a maximum cathode capacity that exceeds 5,700 mAh/g and excellent recharge cycling behavior (＞2,000 cycles at 140 mAh/g,and ＞100 cycles at 1,400 mAh/g).The graphene membrane air cathode can deliver a lifetime capacity of 100,000-300,000 mAh/g,comparable to that of a typical lithium ion battery cathode.The stable operation of Li-air batteries with significantly improved single charge capacities and lifetime capacities comparable to those of Li-ion batteries may offer an attractive high energy density storage alternative for future mobile power supplies.These batteries may provide much longer battery lives and greatly reduced recharge frequency.     

High Performance Lithium‐Ion Batteries Using Layered 2H‐MoTe2 as Anode

The major challenges faced by candidate electrode materials in lithium‐ion batteries (LIBs) include their low electronic and ionic conductivities. 2D van der Waals materials with good electronic conductivity and weak interlayer interaction have been intensively studied in the electrochemical processes involving ion migrations. In particular, molybdenum ditelluride (MoTe₂) has emerged as a new material for energy storage applications. Though 2H‐MoTe₂ with hexagonal semiconducting phase is expected to facilitate more efficient ion insertion/deinsertion than the monoclinic semi‐metallic phase, its application as an anode in LIB has been elusive. Here, 2H‐MoTe₂, prepared by a solid‐state synthesis route, has been employed as an efficient anode with remarkable Li⁺ storage capacity. The as‐prepared 2H‐MoTe₂ electrodes exhibit an initial specific capacity of 432 mAh g^?1 and retain a high reversible specific capacity of 291 mAh g^?1 after 260 cycles at 1.0 A g^?1. Further, a full‐cell prototype is demonstrated by using 2H‐MoTe₂ anode with lithium cobalt oxide cathode, showing a high energy density of 454 Wh kg^?1 (based on the MoTe₂ mass) and capacity retention of 80% over 100 cycles. Synchrotron‐based in situ X‐ray absorption near‐edge structures have revealed the unique lithium reaction pathway and storage mechanism, which is supported by density functional theory based calculations.     

P2-type Na(x)[Fe(1/2)Mn(1/2)]O2 made from earth-abundant elements for rechargeable Na batteries

Rechargeable lithium batteries have risen to prominence as key devices for green and sustainable energy development. Electric vehicles, which are not equipped with an internal combustion engine, have been launched in the market. Manganese- and iron-based positive-electrode materials, such as LiMn(2)O(4) and LiFePO(4), are used in large-scale batteries for electric vehicles. Manganese and iron are abundant elements in the Earth's crust, but lithium is not. In contrast to lithium, sodium is an attractive charge carrier on the basis of elemental abundance. Recently, some layered materials, where sodium can be electrochemically and reversibly extracted/inserted, have been reported. However, their reversible capacity is typically limited to 100 mAh g(-1). Herein, we report a new electrode material, P2-Na(2/3)[Fe(1/2)Mn(1/2)]O(2), that delivers 190 mAh g(-1) of reversible capacity in the sodium cells with the electrochemically active Fe(3+)/Fe(4+) redox. These results will contribute to the development of rechargeable batteries from the earth-abundant elements operable at room temperature.     

α‐Fe2O3 Nanoparticles Decorated C@MoS2 Nanosheet Arrays with Expanded Spacing of (002) Plane for Ultrafast and High Li/Na‐Ion Storage

MoS₂ nanosheets as a promising 2D nanomaterial have extensive applications in energy storage and conversion, but their electrochemical performance is still unsatisfactory as an anode for efficient Li⁺/Na⁺ storage. In this work, the design and synthesis of vertically grown MoS₂ nanosheet arrays, decorated with graphite carbon and Fe₂O₃ nanoparticles, on flexible carbon fiber cloth (denoted as Fe₂O₃@C@MoS₂/CFC) is reported. When evaluated as an anode for lithium‐ion batteries, the Fe₂O₃@C@MoS₂/CFC electrode manifests an outstanding electrochemical performance with a high discharge capacity of 1541.2 mAh g^?1 at 0.1 A g^?1 and a good capacity retention of 80.1% at 1.0 A g^?1 after 500 cycles. As for sodium‐ion batteries, it retains a high reversible capacity of 889.4 mAh g^?1 at 0.5 A g^?1 over 200 cycles. The superior electrochemical performance mainly results from the unique 3D ordered Fe₂O₃@C@MoS₂ array‐type nanostructures and the synergistic effect between the C@MoS₂ nanosheet arrays and Fe₂O₃ nanoparticles. The Fe₂O₃ nanoparticles act as spacers to steady the structure, and the graphite carbon could be incorporated into MoS₂ nanosheets to improve the conductivity of the whole electrode and strengthen the integration of MoS₂ nanosheets and CFC by the adhesive role, together ensuring high conductivity and mechanical stability.     

Mesoporous SnO2@carbon core-shell nanostructures with superior electrochemical performance for lithium ion batteries

SnO2@carbon nanostructure composites are prepared by a simple hydrothermal method. The composite exhibits unique structure, which consists of a mesoporous SnO2 core assembled of very small nanoparticles and a carbon shell with 10 nm thickness. The mesoporous SnO2@carbon core-shell nanostructures manifest superior electrochemical performance as an anode material for lithium ion batteries. The reversible specific capacity of the composite is about 908 mAh g(-1) for the first cycle and it can retain about 680 mAh g(-1) after 40 charge/discharge cycles at a current density of 0.3 C. Moreover, it shows excellent rate capability even at the high rate of 4.5 C. The enhanced performance was attributed to the mesoporous structure and a suitable carbon coating.     

Ultrahigh Rate Performance of Hollow Antimony Nanoparticles Impregnated in Open Carbon Boxes for Sodium‐Ion Battery under Elevated Temperature

Antimony is a competitive and promising anode material for sodium‐ion batteries (SIBs) due to its high theoretical capacity. However, the poor rate capability and fast capacity fading greatly restrict its practical application. To address the above issues, a facile and eco‐friendly sacrificial template method is developed to synthesize hollow Sb nanoparticles impregnated in open carbon boxes (Sb HPs@OCB). The as‐obtained Sb HPs@OCB composite exhibits excellent sodium storage properties even when operated at an elevated temperature of 50 °C, delivering a robust rate capability of 345 mAh g^?1 at 16 A g^?1 and rendering an outstanding reversible capacity of 187 mAh g^?1 at a high rate of 10 A g^?1 after 300 cycles. Such superior electrochemical performance of the Sb HPs@OCB can be attributed to the comprehensive characteristics of improved kinetics derived from hollow Sb nanoparticles impregnated into 2D carbon nanowalls, the existence of robust Sb? O? C bond, and enhanced pseudocapacitive behavior. All those factors enable Sb HPs@OCB great potential and distinct merit for large‐scale energy storage of SIBs.     

In situ synthesis of SnO2/graphene nanocomposite and their application as anode material for lithium ion battery

SnO₂/graphene nanocomposite was prepared via an in situ chemical synthesis method. The nanocomposite was characterized by X-ray diffraction, filed emission scanning electron microscope and transmission electron microscope, which revealed that tiny SnO₂ nanoparticles could be homogeneously distributed on the graphene matrix. The electrochemical performance of the SnO₂/graphene nanocomposite as anode material was measured by galvanostatic charge/discharge cycling. The SnO₂/graphene nanocomposite showed a reversible capacity of 665 mAh/g after 50 cycles and an excellent cycling performance for lithium ion battery, which was ascribed to the three-dimensional architecture of SnO₂/graphene nanocomposite. These results suggest that SnO₂/graphene nanocomposite would be a promising anode material for lithium ion battery.