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Aqueous lithium‐ion batteries (ALIBs) have attracted extensive interest since the safety problems of traditional lithium‐ion batteries are waived. Although the energy density of ALIBs is improved, their rate capability and power density are still poor due to the slow Li+ diffusivity of the existing anode materials, and their cyclic stability is also poor. Here, W7Nb4O31 nanorods with very fast‐ and stable‐charging capability are explored as a new anode material for ALIBs for the first time. This material owns different tetragonal tungsten bronze (TTB) structures together with 4 × 4 ReO3‐type blocks confined by TTB matrices, allowing abundant pentagonal and quadrangular tunnels for Li+ transport. These large‐sized tunnels combine with the large interlayer spacing (≈3.95 Å) not only lead to extremely fast Li+ diffusivity but also small unit‐cell volume variations (maximum 2.1%) during lithiation/delithiation, thereby enabling the LiMn2O4//W7Nb4O31 full cell to possess excellent rate capability with a 50C versus 1C capacity ratio of 68.3%, ultrahigh power density of 9854 W kg–1, and superior cyclic stability with capacity retention of 89.7/66.7/72.0% at 1C/5C/50C over 1000/10 000/10 000 cycles. This comprehensive study demonstrates that the W7Nb4O31 nanorods are highly promising for fast‐ and stable‐charging ALIBs. [ABSTRACT FROM AUTHOR]

Ultra‐long‐life (at least 10 000 cycles) lithium‐ion batteries are very effective for stationary energy‐storage applications. However, even "zero‐strain" materials with small unit‐cell‐volume changes of <1% cannot last for ultra‐long cycles due to gradually accumulated intracrystal strain/stress. Here, Li[Li0.2Cr0.4Ti1.4]O4 is explored as the first absolutely‐zero‐expansion material with unit‐cell‐volume variations of zero during Li+ storage. Its absolutely‐zero‐expansion mechanism is intensively studied, revealing that 16c‐octahedron shrinkage fully offsets 16d‐octahedron expansion through reversible O2− movement. It delivers better cycling stability than, as far as we know, all electrochemical energy‐storage materials previously reported. Its capacity retention at 10 C and 1.0 mg cm−2 after 17 000 cycles reaches 91.5%. When the active‐material loading significantly increases to 6.4 mg cm−2, its capacity retention at 5 C after 500 cycles reaches 95.7%. At an elevated temperature of 45 °C, it not only keeps excellent cycling stability but also exhibits significantly enhanced rate capability. Therefore, Li[Li0.2Cr0.4Ti1.4]O4 is especially suitable for stationary energy storage. [ABSTRACT FROM AUTHOR]

Two-dimensional molybdenum disulfide (MoS2) is considered as a highly promising anode material for lithium-ion batteries (LIBs) due to its unique layer structure, large plane spacing, and high theoretical specific capacity; however, the overlap of MoS2 nanosheets and inherently low electrical conductivity lead to rapid capacity decay, resulting in poor cycling stability and low multiplicative performance. This severely limits its practical application in LIBs. To overcome the above problems, composite fibers with a core//sheath structure have been designed and fabricated. The sheath moiety of MoS2 nanosheets is uniformly anchored by the hydrothermal treatment of the axial of carbon nanofibers derived from an electrospinning method (CNFs//MoS2). The quantity of the MoS2 nanosheets on the CNFs substrates can be tuned by controlling the amount of utilized thiourea precursor. The influence of the MoS2 nanosheets on the electrochemical properties of the composite fibers has been investigated. The synergistic effect between MoS2 and carbon nanofibers can enhance their electrical conductivity and ionic reversibility as an anode for LIBs. The composite fibers deliver a high reversible capacity of 866.5 mA h g−1 after 200 cycles at a current density of 0.5 A g−1 and maintain a capacity of 703.3 mA h g−1 after a long cycle of 500 charge–discharge processes at 1 A g−1. [ABSTRACT FROM AUTHOR]

In this study, a facile method is developed for preparing porous microspheres of lithium titanate (Li4Ti5O12 [LTO]) nanocrystals for use as anode materials of lithium-ion batteries (LIBs). Spray drying combined with solid-state calcination have been applied for the preparation. A sol of TiO2 nanoparticles of several nanometers has been obtained through the quaternary-ammonium-hydroxide-assisted sol–gel process. TiO2 sol is used as a precursor for LTO to ensure a stable mixture of a TiO2 sol with the LiOH aqueous solution, which is crucial for spray drying. Microspheres of 0.5 and 3 μm consisting of LTO nanocrystals of approximately 200 nm are obtained by calcining the spray drying samples. The phase, composition, microstructure, porosity, and electrochemical properties of the obtained samples are investigated. When used as an anode material for LIBs, LTO microspheres exhibit a reversible capacity of 174.7 mAhg−1 at 0.1 C and an excellent cycling stability with capacity retention of 98.6% after 100 cycles at 1 C rate. Furthermore, a remarkable rate capacity of 57.8% is retained at 20 C (vs 0.1 C). [ABSTRACT FROM AUTHOR]

Capacity decay of an intercalating Li+‐storage material is mainly due to the its particle microcracks from stress‐causing volume change. To extend its cycle life, its unit‐cell‐volume change has to be minimized as much as possible. Here, based on a γ‐Li3VO4 model material, the authors explore selective doping as a general strategy to controllably tailor its maximum unit‐cell‐volume change, then clarify the relationship between its crystal‐structure openness and maximum unit‐cell‐volume change, and finally demonstrate the superiority of "zero‐strain" materials within 25–60 °C (especially at 60 °C). With increasing the large‐sized Ge4+ dopant, the unit‐cell volume of γ‐Li3+xGexV1−xO4 becomes larger and its crystal structure becomes looser, resulting in the decrease of its maximum unit‐cell‐volume change. In contrast, the doping with small‐sized Si4+ shows a reverse trend. The tailoring reveals that γ‐Li3.09Ge0.09V0.91O4 owns the smallest maximum unit‐cell‐volume change of 0.016% in the research field of intercalating Li+‐storage materials. Consequently, γ‐Li3.09Ge0.09V0.91O4 nanowires exhibit excellent cycling stability at 25/60 °C with 94.8%/111.5% capacity‐retention percentages after 1800/1500 cycles at 2 A g−1. This material further shows large reversible capacities, proper working potentials, and high rate capability at both temperatures, fully demonstrating its great application potential in long‐life lithium‐ion batteries. [ABSTRACT FROM AUTHOR]

The application of Fe3O4 as anode material for lithium‐ion batteries is hindered by the capacity fade owing to its enormous volume expansion and the inherent low conductivity. Herein, carbon‐encapsulated Fe3O4 nanospheres anchored on carbon nanotubes (Fe3O4/CNTs@C) have been successfully fabricated. The obtained Fe3O4/CNTs@C composites show that numerous Fe3O4 nanospheres are held and connected by the CNT network, forming a composite of porous three‐dimensional structure. The unique structure improves the conductivity and structural stability of the Fe3O4/CNTs@C composite. The encapsulation with carbon enhances the contact between Fe3O4 nanospheres and carbon nanotubes and shortens the ion‐transport path. As a result, the Fe3O4/CNTs@C delivers a high capacity of 612 mA h g−1 at 1 A g−1, even after 200 cycles, and shows a superior rate performance of 523 mA h g−1 at 5 A g−1. This work provides a preparation strategy that could be easily applied to other functional materials for energy storage and/or catalysis. [ABSTRACT FROM AUTHOR]

Three-dimensional reduced graphene oxide (RGO) matrix decorated with nanoflowers of layered MoS2 (denoted as 3D MoS2/RGO) have been synthesized via a facile one-pot stepwise hydrothermal method. Graphene oxide (GO) is used as precursor of RGO and a 3D GO network is formed in the first-step of hydrothermal treatment. At the second stage of hydrothermal treatment, nanoflowers of layered MoS2 form and anchor on the surface of previously formed 3D RGO network. In this preparation, thiourea not only induces the formation of the 3D architecture at a relatively low temperature, but also works as sulfur precursor of MoS2. The synthesized composites have been investigated with XRD, SEM, TEM, Raman spectra, TGA, N2 sorption technique and electrochemical measurements. In comparison with normal MoS2/RGO composites, the 3D MoS2/RGO composite shows improved electrochemical performance as anode material for lithium-ion batteries. A high reversible capacity of 930 mAh ⋅ g − 1 after 130 cycles under a current density of 200 mA ⋅ g − 1 as well as good rate capability and superior cyclic stability have been observed. The superior electrochemical performance of the 3D MoS2/RGO composite as anode active material for lithium-ion battery is ascribed to its robust 3D structures, enhanced surface area and the synergistic effect between graphene matrix and the MoS2 nanoflowers subunit. MoS2 nanoflowers anchored onto three-dimensional reduced graphene oxide (RGO) matrix (denoted as 3D MoS2/RGO) have been successfully fabricated by a facile one-pot stepwise hydrothermal method. The as-synthesized 3D MoS2/RGO composites exhibited improved cycling stability and outstanding rate capacity as anode active material for lithium-ion batteries. [ABSTRACT FROM AUTHOR]

A one-step high-temperature solvothermal approach to the synthesis of monolayer or bilayer MoS2 anchored onto reduced graphene oxide (RGO) sheet (denoted as MoS2/RGO) is described. It was found that single-layered or double-layered MoS2 were synthesized directly without an extra exfoliation step and well dispersed on the surface of crumpled RGO sheets with random orientation. The prepared MoS2/RGO composites delivered a high reversible capacity of 900 mAhg − 1 after 200 cycles at a current density of 200 mAg − 1 as well as good rate capability as anode active material for lithium ion batteries. This one-step high-temperature hydrothermal strategy provides a simple, cost-effective and eco-friendly way to the fabrication of exfoliated MoS2 layers deposited onto RGO sheets. Monolayer or bilayer MoS2 anchored onto reduced graphene oxide (RGO) sheet (denoted as MoS2/RGO) has been successfully fabricated by a one-step high-temperature solvothermal approach up to 350∘C. The as-synthesized MoS2/RGO composites delivered a high reversible capacity of 900 mAhg−1 after 200 cycles at a current density of 200 mAg−1 as well as good rate capability as anode active material for lithium ion batteries. [ABSTRACT FROM AUTHOR]

Spinel structured Li4Ti5O12 (LTO) spheres modified with carbon (Carbon/LTO composites) using Chinese yam (CY) as carbon source have been obtained by a hydrothermal method combining with a calcining at 700 °C in N2 atmosphere. The influences of the additions of CY on the morphology, structure, carbon content and also the electrochemical properties of the resulted carbon/LTO composite spheres have been investigated in details. SEM and TEM investigations show that all the composites possess spherical morphology and consist of nanosized Li4Ti5O12 crystals modified with carbon. With the increase of CY additions, the size of Li4Ti5O12 primary crystals decrease gradually, and reach to a turn over point and then the crystal size turn to large ones when the CY content increased further. It has been demonstrated that carbon modification of Li4Ti5O12 with Chinese yam as carbon source could efficiently improve the electrochemical performance of Li4Ti5O12. One of the composite sample named as C/LTO‐10 shows an ultrahigh initial specific capacity of about 211.9 mAh ⋅ g−1 at a current density of 1 C. It shows excellent cycle performance and maintains a specific capacity of 184.5 mAh ⋅ g−1 even after 300 cycles. A specific capacity of 123.5 mAh ⋅ g−1 still could be delivered at a high current density of 30 C, exhibiting also superior rate capability. Composites of Li4Ti5O12 modified with N doped carbon have been prepared with Chinese yam as carbon precursor by using a hydrothermal method and followed by a calcination process at 700 °C. The composites show an ultrahigh initial specific capacity of about 211.9 mAh.g−1 at a current density of 1 C. Even after 300 cycles a specific capacity of 184.5 mAh ⋅ g−1 still could be maintained. A specific capacity of 123.5 mAh ⋅ g−1 were delivered at a high current density of 30 C, exhibiting also superior rate capability. [ABSTRACT FROM AUTHOR]

Ni3S2 nanocrystals wrapped by thin carbon layer and anchored on the sheets of reduced graphene oxide (Ni3S2@C/RGO) have been synthesized by a spray-coagulation assisted hydrothermal method and combined with a calcination process. Cellulose, dissolved in Thiourea/NaOH aqueous solution is chosen as carbon sources and mixed with graphene oxide via a spray-coagulation method using graphene suspension as coagulation bath. The resulted cellulose/graphene suspension is utilized as solvent for dissolving of Ni(NO3)2 and then used as raw materials for hydrothermal preparation of the Ni3S2@C/RGO composites. The structure of the composites has been investigated and their electrochemical properties are evaluated as anode material for lithium-ion batteries. The Ni3S2@C/RGO sample exhibits increasing reversible capacities upon cycles and shows a superior rate performance as well. Such kinds of promising performance have been ascribed to the wrapping effect of carbon layer which confines the dislocation of the polycrystals formed upon cycles and the enhanced conductivity as the integration of RGO conductive substrate. Discharge capacities up to 850 and 630 mAh·g−1 at current densities of 200 and 5000 mA·g−1, respectively, are obtained. The evolution of electrochemical performance of the composites with structure variation of the encapsulated Ni3S2 nanocrystals has been revealed by ex-situ TEM and XRD measurements. [ABSTRACT FROM AUTHOR]

A well-designed strategy is demonstrated to consecutively engineer a homogeneously dispersed cobalt monoxide nanoparticle on reduced graphene oxide as a composite anode (CoO@RGO) and a nanosized lithium cobalt oxide (LiCoO 2 , LCO) cathode material, starting from metallic Co foils and few-layered graphene oxide (GO) aqueous suspension. [Display omitted] Downsizing the electrochemically active materials in both cathodic and anodic electrodes commonly brings about enhanced lithium-ion storage performances. It is particularly meaningful to explore simplified and effective strategies for exploiting nanosized electrode materials in the advanced lithium-ion batteries. In this work, the spontaneous reaction between few-layered graphene oxide (GO) and metallic cobalt (Co) foils in mild hydrothermal condition is for the first time employed to synthesize a reduced graphene oxide (RGO) supported nanosized cobalt monoxide (CoO) anode material (CoO@RGO). Furthermore, the CoO@RGO sample is converted to nanosized lithium cobalt oxide cathode material (LiCoO 2 , LCO) by taking the advantages of the self-templated effect. As a result, both the CoO@RGO anode and the LCO cathode exhibit inspiring lithium-ion storage properties. In half-cells, the CoO@RGO sample maintains a reversible capacity of 740.6 mAh·g−1 after 300 cycles at the current density of 1000 mA·g−1 while the LCO sample delivers a reversible capacity of 109.1 mAh·g−1 after 100 cycles at the current density of 100 mA·g−1. In the CoO@RGO//LCO full-cells, the CoO@RGO sample delivers a reversible capacity of 553.9 mAh·g−1 after 50 cycles at the current density of 200 mA·g−1. The reasons for superior electrochemical behaviors of the samples have been revealed, and the strategy in this work can be considered to be straightforward and effective for engineering both anode and cathode materials for lithium-ion batteries. [ABSTRACT FROM AUTHOR]

The chelation reaction between LS-Na and SnCl 2 under mild hydrothermal condition generates the SnCl 2 @LS sample with a uniform distribution of Sn2+ in the LS domains, which can be further dispersed by GO sheets via a redox coprecipitation reaction. After thermal treatment, the SnCl 2 @LS@GO sample can be converted to the SnO 2 /LSC/RGO composite with improved micro-structure. [Display omitted] Tin dioxide (SnO 2) is widely recognized as a high-performance anode material for lithium-ion batteries. To simultaneously achieve satisfactory electrochemical performances and lower manufacturing costs, engineering nano-sized SnO 2 and further immobilizing SnO 2 with supportive carbon frameworks via eco-friendly and cost-effective approaches are challenging tasks. In this work, biomass sodium lignosulfonate (LS-Na), stannous chloride (SnCl 2) and a small amount of few-layered graphene oxide (GO) are employed as raw materials to engineer a hierarchical carbon framework supported SnO 2 nanocomposite. The spontaneous chelation reaction between LS-Na and SnCl 2 under mild hydrothermal condition generates the corresponding SnCl 2 @LS sample with a uniform distribution of Sn2+ in the LS domains, and the SnCl 2 @LS sample is further dispersed by GO sheets via a redox coprecipitation reaction. After a thermal treatment, the SnCl 2 @LS@GO sample is converted to the final SnO 2 /LSC/RGO sample with an improved microstructure. The SnO 2 /LSC/RGO nanocomposite exhibits excellent lithium-ion storage performances with a high specific capacity of 938.3 mAh/g after 600 cycles at 1000 mA g−1 in half-cells and 517.1 mAh/g after 50 cycles at 200 mA g−1 in full-cells. This work provides a potential strategy of engineering biomass derived high-performance electrode materials for rechargeable batteries. [ABSTRACT FROM AUTHOR]

The redox coprecipitation reaction between the Fe foil, H 3 BTC molecules and GO sheets in mild hydrothermal condition leads to the in situ formation of Fe-BTC MOFs directly on the RGO sheets. The RGO sheets effectively inhibit the severe aggregation of small sized Fe-BTC domains, and the well distributed Fe-BTC domains could prevent the spontaneous restacking of the RGO sheets. [Display omitted] Fe based metal organic framework (MOF) materials are being extensively investigated as a precursor sample for engineering carbon supported iron containing nanoparticles composites. Rational design and engineering Fe-containing MOFs with optimized structures using economic and eco-friendly methods is a challenging task. In this work, 1,3,5-benzenetricarboxylic acid (C 9 H 6 O 6 , trimesic acid, H 3 BTC) and metal Fe are employed to synthesize a MOF sample Fe-BTC in a mild hydrothermal condition. Moreover, with the addition of a small quantity of graphene oxide (GO) as dispersant, a redox coprecipitation reaction has taken place where small Fe-BTC domains well dispersed by reduced graphene oxide (RGO). The Fe-BTC/RGO intermediate sample is finally converted to the hierarchical Fe 3 O 4 @C/RGO composite, which delivers an ultrahigh specific capacity of 1262.61 mAh·g−1 at 200 mA·g−1 after 150 cycles and a superior reversible capacity of 910.65 mAh·g−1 at 1000 mA·g−1 after 300 cycles in half cells. The full cell performance for the Fe 3 O 4 @C/RGO composite have been studied. It is also revealed that the improved structural stability, high pseudocapacitive contribution and enhanced lithium-ion and electron transportation conditions jointly guarantee the outstanding lithium-ion storage performances for the Fe 3 O 4 @C/RGO composite over long-time cycling. The synthesized samples have good potential for wider application. [ABSTRACT FROM AUTHOR]

[Display omitted] • Flexible microspheres consisting of Si nanoparticles, CNTs and amorphous carbon are prepared. • The mass producible spray-drying method is used for building the stable composite microspheres. • The carbon nanotubes and amorphous carbon act as conductive pathway and relieve internal stresses. • The interpenetrating structure improves the performance of Si nanoparticles as anode materials. The huge volumetric expansion (> 300 %) of Si that occurs during the charge–discharge process makes it to have poor cycling ability and weak stable structure. These factors are considered as critical obstacles to the further development of Si as anode for lithium-ion batteries (LIBs). Herein, novel 3D interpenetrating microspheres, i.e., Si@C-CNTs, which consist of silicon nanoparticles interpenetrated with carbon nanotubes (CNTs) and stuck with amorphous carbon (C) have been designed and prepared via a spray-drying assisted approach. As anode of LIBs, Si@C-CNTs microspheres can achieve high silicon loadings of around 86 % and a high initial coulomb efficiency of 80.8 %. The electrodes maintain a reversible specific capacity of 1585.9mAh/g at 500 mA g−1 after 200 cycles, and deliver an excellent rate capability of 756.4 mAh/g at 5 A g−1. The outstanding performance of Si@C-CNTs can be due to their 3D interpenetrating structure and the synergy effect between the CNTs network and amorphous carbon therein. They synergistically act as conductive matrices which significantly improve the conductivity of the composite; they also act binders and reinforcing skeleton which help the composite spheres to have stable structure. Especially, the latter (reinforcing skeleton) alleviates the volumetric effect induced by the expansion and shrinkage of silicon particles during lithiation. The unique architecture provides an ideal model that can be used to design Si-based composite anode for advanced LIBs. [ABSTRACT FROM AUTHOR]

A hierarchical Fe 3 O 4 @RPC/RGO composite is synthesized based on the redox reaction between the nano-irons from ferric gallate (Fe-GA) derived Fe/RPC and graphene oxide sheets (GO) under mild hydrothermal condition. [Display omitted] Ferric gallate (Fe-GA), an ancient metal–organic framework (MOF) material, has been recently employed as an eco-friendly and cost-effective precursor sample to synthesize a porous carbon confined nano-iron composite (Fe/RPC), and the Fe element in the Fe/RPC sample could be further oxidized to Fe 3 O 4 nanocrystals in a 180 °C hydrothermal condition. On this foundation, this work reports an optimized approach to engineering a hierarchical one-dimensional porous carbon and two-dimensional reduced graphene oxide (RGO) supporting framework with Fe 3 O 4 nanoparticles well dispersed. Under mild hydrothermal condition, the redox reaction between metal iron atoms from Fe/RPC and surface functional radicals from few-layered graphene oxide sheets (GO) is triggered. As a result, reinforced microstructure and improved atomic efficiency have been achieved for the Fe 3 O 4 @RPC/RGO sample. The homogeneously dispersed Fe 3 O 4 nanoparticles with controlled size are anchored on the surface of the larger sized RGO coating layers while the smaller sized RPC domains are embedded between the RGO sheets as spacer. Challenges including spontaneous aggregation of RPC, over exposure of Fe 3 O 4 nanoparticles and excessive restacking of RGO have been significantly inhibited. Furthermore, micro-sized carbon fiber (CF) is chosen as a structural reinforcement additive during electrode fabrication, and the Fe 3 O 4 @RPC/RGO sample delivers a good specific capacity of 1170.5 mAh·g−1 under a current rate of 1000 mA·g−1 for 500 cycles in the half cell form. The reasons for superior electrochemical behaviors have been revealed and the lithium-ion storage performances of the Fe 3 O 4 @RPC/RGO sample in the full cell form have been preliminarily investigated. [ABSTRACT FROM AUTHOR]

Capacity decay of an intercalating Li+‐storage material is mainly due to the its particle microcracks from stress‐causing volume change. To extend its cycle life, its unit‐cell‐volume change has to be minimized as much as possible. Here, based on a γ‐Li3VO4 model material, the authors explore selective doping as a general strategy to controllably tailor its maximum unit‐cell‐volume change, then clarify the relationship between its crystal‐structure openness and maximum unit‐cell‐volume change, and finally demonstrate the superiority of "zero‐strain" materials within 25–60 °C (especially at 60 °C). With increasing the large‐sized Ge4+ dopant, the unit‐cell volume of γ‐Li3+xGexV1−xO4 becomes larger and its crystal structure becomes looser, resulting in the decrease of its maximum unit‐cell‐volume change. In contrast, the doping with small‐sized Si4+ shows a reverse trend. The tailoring reveals that γ‐Li3.09Ge0.09V0.91O4 owns the smallest maximum unit‐cell‐volume change of 0.016% in the research field of intercalating Li+‐storage materials. Consequently, γ‐Li3.09Ge0.09V0.91O4 nanowires exhibit excellent cycling stability at 25/60 °C with 94.8%/111.5% capacity‐retention percentages after 1800/1500 cycles at 2 A g−1. This material further shows large reversible capacities, proper working potentials, and high rate capability at both temperatures, fully demonstrating its great application potential in long‐life lithium‐ion batteries. [ABSTRACT FROM AUTHOR]

A simplified coprecipitation strategy is explored for the synthesis of Zn-doped tin oxide samples, and the Zn-doped tin monoxide nanobelts are further used to successfully engineer hierarchical reduced graphene oxide and carbon nanotube supported Zn-doped tin dioxide composite. [Display omitted] In this work, a rapid coprecipitation reaction is developed to obtain nano-sized Zn-doped tin oxide samples (Zn-SnO-II or Zn-SnO 2 -IV) for the first time by simply mixing tin ion (Sn2+ or Sn4+) and zinc ion (Zn2+) containing salts in a mild aqueous condition. Characterization results illustrate the Zn-SnO-II sample is constituted by an overwhelming quantity of Zn-doped SnO nanobelts and a small quantity of Zn-doped SnO 2 nanoparticles. The redox reaction between the Sn2+ ions from the Zn-SnO-II sample and the surface oxygen-containing functional groups from functionalized carbon nanotube (F-CNT) and graphene oxide (GO) leads to the formation of the final Zn-SnO 2 /CNT@RGO composites. As an anode active material for lithium-ion batteries, the Zn-SnO 2 /CNT@RGO product showed superior electrochemical performance than the controlled Zn-SnO 2 /CNT and Zn-SnO 2 /RGO samples, which had a high gravimetric capacity of 901.3 mAh·g−1 at a high charge and discharge current of 1000 mA·g−1 after 300 cycles and excellent rate capability. The reaction mechanism for the successful synthesis of the Zn-doped tin oxide samples has been proposed, and the insight into the outstanding lithium-ion storage performance for the Zn-SnO 2 /CNT@RGO composite has been revealed. The synthetic processes for both the Zn-doped tin oxides and derived carbon supported composites are straightforward and involve no harsh conditions nor complicated treatment, which have good potential for massive production and application in wider fields. [ABSTRACT FROM AUTHOR]

RGO supported larger FeOOH nanoparticles and smaller SnO 2 quantum dots hierarchical composite is straightforward prepared for long-life and high-rate lithium-ion storage. The synergetic effect between two or more electrochemically active materials usually leads to superior lithium-ion storage performance. This work demonstrates a straightforward and effective approach to synthesize a reduced graphene oxide (RGO) encapsulated larger goethite (FeOOH) nanoparticles and smaller tin dioxide (SnO 2) quantum dots hierarchical composite (SnO 2 @FeOOH/RGO). The synthesized SnO 2 @FeOOH/RGO composite exhibits encouraging lithium-ion storage capability than controlled SnO 2 /RGO and FeOOH/RGO samples with a stable specific capacity of 638 mAh·g−1 under a high current rate of 1000 mA·g−1 for 2000 continual cycles and good rate performance. The redox reaction between reductive metal-atoms or metal-ions and graphene oxide (GO) sheets guarantees an effective immobilization of corresponding nano-sized metal oxide and hydroxide crystals by the RGO framework. Furthermore, the engineered larger FeOOH crystals engage in lithium-ion storage and perform an ideal spacer between the restacked RGO sheets. Therefore, smaller SnO 2 quantum dots' inherent excellent rate capability is extensively promoted due to the improvement of electrolyte diffusion and electron transfer condition. The sample design and fabrication method in this work might be developed for broader applications. [ABSTRACT FROM AUTHOR]

Electrospinning has been used as a convenient technology to produce high-energy and self-standing anodes for lithium-ion batteries (LIBs) by encapsulating silicon nanoparticles (Si/NPs) into carbon nanofibers (CNF). However, the inhomogeneous distribution of Si/NPs in CNF results in low coulombic efficiency, rapid capacity decay and slow kinetics during cycling process which hinder the practical application of this promising composite anode. In this work, a principle of universal design is applied to the manufacture of Si-CNF composites, in this way, a self-standing electrode with homogeneous distribution of Si/NPs in CNF (Si//PCNF-15) is developed by introducing triblock copolymer Pluronic P123 (polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer) as dispersant and pore directing agent. As anode of LIBs, the Si//PCNF-15 exhibits outstanding electrochemical performance and considerable flexibility due to the homogeneous dispersion of Si nanoparticles and high graphitization of the carbon network. As results, a specific capacity of 1074.8 mAh g−1 at 0.3 A g−1 and a rate capacity of 236.1 mAh g−1 at 10 A g−1 have been delivered when it is explored as a self-standing anode for LIBs. This work provides a universal approach for developing self-standing anodes of composite fibers with nanoparticles dispersed homogeneously in CNF. [Display omitted] • Composite fibers of carbon encapsulated Si nanoparticles are got by electrospinning. • P123 surfactant play dual-role as Si dispersant and pore director of carbon nanofibers. • Even dispersion of Si nanoparticles and formation of mesopores are achieved by P123. • The composite is used as self-standing anode for high-performance lithium-ion battery. [ABSTRACT FROM AUTHOR]

Hierarchically structured microspheres consisting of carbon coated porous silicon have been prepared by a spray drying assisted magnesiothermic reduction using gelatin as carbon precursor and SiO 2 as silicon source. Gelatin is deposited on the surface of SiO 2 nanospheres during spray drying, which plays also as binder in assembling SiO 2 nanospheres to form the microspheres. After the magnesiothermic reduction, gelatin is carbonized and deposited in-situ on the surface of nanospheres and porous silicon nanospheres wrapped with a carbon layer are derived. The thickness of carbon coating and the porosity of obtained Si/C composite nanospheres can be modified by tuning the content of gelatin in the suspension. Two desired purposes, i.e. downsizing of Si particles and in-situ carbon coating of the nanoparticles have been achieved by this preparation. The resulted Si/C composite microspheres show superior electrochemical performance and high structure stability as anode materials for Li-ion batteries. An initial reversible capacity of 1638 mAh g−1 and excellent capacity retention of 523 mAh g−1 after 300 cycles can be achieved at a current density of 200 mA g−1. The formation mechanism of the hierarchically structured microspheres and the variation of porosity for the individual Si nanospheres have been investigated and discussed in details. Image 1 [ABSTRACT FROM AUTHOR]