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We designed the hollow ZnCoO microsphere with meshy surface by means of ormaldehyde bubble-induced method. To avoid the occurring of the side reaction on the interface caused by its high specific surface area, three-dimensional (3D) polypyrrole/sodium alginate (PPy/SA) composite via the situ polymerization of pyrrole in an aqueous solution of SA was used as the coating layer of ZnCoO to form lychee-shaped ZnCoO@PPy/SA microsphere. The PPy/SA was found to have a more favorable conductivity and mechanical strength than PPy. As anode material for lithium-ion battery, ZnCoO@PPy/SA possesses numerous merits compared with ZnCoO and ZnCoO@PPy. The more outstanding electrochemical performance of ZnCoO@PPy/SA electrode with higher reversible capacity, more excellent long-term cycling stability and better rate capability can be attributed to the porous hollow structure and PPy/SA coating, which not only reduce the path length for Li ions but also accommodate the volume expansion. Such structured composite electrode may have great potential for the application in lithium-ion batteries. [ABSTRACT FROM AUTHOR]

Here, a supramolecular self-assembly hydrogel was designed for SnO-based anode through electrostatic interaction and ionic bonding between poly(allylamine hydrochloride) (PAH) chain and gelator phytic acid. Microrheology measurement was employed to investigate the self-sorting mechanism of the hierarchical nanostructured PAH. Results confirmed that ionically cross-link PAH improves the structural integrity of SnO nanospheres due to the reversible ionic bonding and thus increases the lifetime of the electrodes obviously. Besides, multi-walled carbon nanotubes (MWCNTs) were applied to improve the electrochemical performance of hollow SnO nanospheres due to their high conductivity. Results confirmed that the conductive network constructed by MWCNTs reduces the polarization of the composites while increases the specific capacity of the electrodes. Attributed to the synergistic effect of PAH-60 and MWCNTs, the composite electrodes show excellent electrochemical performance with a reversible capacity of 574 mAh g after 100 cycles at 100 mA g, a discharge capacity of 321 mAh g at 2000 mA g and a spring-back capacity of 506 mAh g at 200 mA g. Additionally, the prepared composite electrodes were observed to have a complete network structure after rate capability test, demonstrating a superior structural stability. [ABSTRACT FROM AUTHOR]

A novel MWCNT/long nanotubular TiO(B) loaded with SnO nanocrystals (SnONC/TiO(B)NT/MWCNT) ternary composite has been prepared by two-step hydrothermal method and used as the anode material for the first time. In this work, the mechanical stirring improved the diffusion and surface reaction rates of reactants and promoted the appearance of longer intermediate TiO(B) nanosheets, leading to the formation of TiO(B) nanotubes with a length of ~9 μm. Among the SnONC/TiO(B)NT/MWCNT composite, the wrapping and mechanical supporting functions of TiO(B) nanotubes can effectively avoid the pulverization and aggregation of SnO nanocrystals (SnONC) in lithium-ion charging and discharging process. Moreover, the synergistic effects of nanotubular TiO(B) coating layer and three-dimensional interconnected network structure composed of TiO(B) nanotubes and MWCNT were taken to mitigate volume expansion of SnONC and improve the transport of lithium ion and electron in the network. Tested as anode materials, the SnONC/TiO(B)NT/MWCNT composite maintained 211 mAh g at 3000 mA g after three testing processes with alternative current density of 200 and 3000 mA g and could rebound to 338 mAh g at a current density of 200 mA g, indicating an effective way to optimize electrochemical properties of SnO as anode material. [ABSTRACT FROM AUTHOR]

A novel nano-Sn particle/poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)/poly(vinyl alcohol) core-shell hierarchical composite (nano-Sn/PEDOT:PSS/PVA CSHC) was fabricated for the first time and evaluated as a high-performance anode material in lithium ion batteries (LIBs). The core-shell hierarchical structure of the composite was revealed by field-emission scanning electron microscope and transmission electron microscope; the components of the composite were investigated by X-ray diffraction and fourier transform infrared spectroscopy; the nano-Sn particle content in the composite was obtained by thermogravimetric analysis and the electrochemical performance was studied by galvanostatic charge/discharge cycling tests and electrochemical impedance spectroscopy. When used as LIB anode material, the nano-Sn/PEDOT:PSS/PVA CSHC electrode exhibited high reversible capacity (568 mA h g after 100 charge/discharge cycles at a current density of 100 mA g), superior cycling stability (capacity retention of 66.0 % after 100 cycles), good rate performance (143 mA h g at 1500 mA g) and low charge transfer resistance compared to pristine nano-Sn particle and nano-Sn/PEDOT:PSS composite electrodes. The improved electrochemical performance can be attributed to the core-shell hierarchical structure. The results show that the nano-Sn/PEDOT:PSS/PVA CSHC is a promising anode candidate for next-generation LIBs. [ABSTRACT FROM AUTHOR]

In order to optimize the electrode system of lithium-ion batteries (LIBs) for problems like lithium-ion diffusion, electron transport, and large volume change during cycling processes, a novel three-dimensional (3D) hybrid FeO nanotube array anode coated by polypyrrole (FeO@PPy) is synthesized via a sacrificial template-accelerated hydrolysis method followed by a chemical vapor-phase polymerization process. In the hollow core-shell nanostructures, the conducting PPy layer could not only facilitate the electron transport, but also force the core to expand inward into the hollow space, which allows for free volume expansion of the FeO without mechanical breaking. Besides, the static outer surface is contributed to form a stable solid electrolyte interface film. As a result, the integration of 3D hybrid nanostructure electrode is capable of retaining a high capacity of 665 mA h g after 150 cycles with a coulombic efficiency of above 97 %, revealing better cycling properties compared with bare FeO nanotube arrays' anode. This nanoengineering strategy is proven to be an ideal candidate for the development of high-performance anode for LIBs. [ABSTRACT FROM AUTHOR]

Nanostructured hollow Sn-Cu multi-phase composite nanoparticles anode that contains Sn and CuSn was synthesized via galvanic replacement reaction using Sn nanoparticles as a sacrificial template. The sacrificial oxidation of Sn and simultaneous reduction of Cu on the surface because of the redox potential difference is proposed to account for the formation of hollow Sn-Cu nanostructures. The structural evolution of the Sn-Cu hollow nanoparticle, in the process of galvanic replacement and structure, composition changes during charge/discharge processes were studied based on scanning electron microscope, X-ray powder diffraction, transmission electron microscopy, and energy dispersive X-ray spectroscopy investigations. The electrochemical properties of the samples were evaluated by galvanostatic discharge-charge cycling, cyclic voltammetry, and electrochemical impedance spectroscopy. Compared with solid Sn-Cu nanoparticles, hollow Sn-Cu nanoparticles showed better capacity retention. The improved electrochemical performance may be attributed to the stable hollow structure and the combination of CuSn. The facile solution-based process and excellent cycling stability show great potential of the multi-phase Sn-Cu hollow composite nanoparticles as an anode material for lithium-ion batteries. [ABSTRACT FROM AUTHOR]

The novel Sn-Cu nanotubes enveloped in three-dimensional (3D) hierarchical polyaniline (PANI) hydrogel (Sn-Cu/PANI) were successfully prepared as a high performance anode for lithium-ion battery. The binder-free electrode exhibits reversible capacity of 548 mA h g −1 after 500 cycles and admirable rate capacity even up to 5000 mA g −1 . The exceptional electrochemical performance of Sn-Cu/PANI hydrogel could be attributed to the unique structure: (1) The inactive Cu matrix in binary Sn-Cu compounds and the tubular construction conduce to relieve the volume swing; The high porosity originated from galvanic replacement reaction accelerates ions transmission, which contributes to rapid charging and discharging. (2) The 3D porous PANI framework offers a continuous electron and lithium ions transport network among the whole electrode; the hierarchical PANI serves as mechanical support to accommodate the stress related to the large volume change of Sn-Cu nanotubes, thus reducing the risk of electrode pulverization. [ABSTRACT FROM AUTHOR]

Multilayer Zn-doped SnO 2 nanospheres are successfully synthesized by using Sn/Zn bimetal-organic nanoparticles as precursor. These multilayer spheres are found to be very suitable for solving the critical volume expansion problem and mass transfer property due to its high surface area, small crystal size and hollow structure, which is critical for high capacity metal oxide electrodes for lithium-ion batteries. Moreover, the covalently interconnected three-dimensional graphene foams encapsulated these multilayer spheres are successfully obtained through self-assembly effect and chemical cross-linking of graphene oxide nanosheets. The graphene network could further greatly improve the cycling stability and rate capability of the Zn-doped SnO 2 spheres electrode due to its flexible buffering matrix and high electric conduction. As a result, the graphene encapsulating multilayer Zn-doped SnO 2 spheres anodes exhibit excellent rate capacity and a high reversible capacity of 446 mA h g −1 even after 1000 cycles at the current density of 1 A g −1 . These excellent electrochemical performances are ascribed to its large specific surface area, fast electron/ion transfer, and stable electrode structure. Furthermore, this strategy using covalently interconnected 3D graphene foams encapsulate the Zn-doped SnO 2 spheres not only develops a high performance anode material with long cycle life but also holds great promise for binder-free lithium ion batteries. [ABSTRACT FROM AUTHOR]

A novel reversible interaction in polymeric nanoparticles is used to induce hollow Sn 4+ -MOPs. Then ultrafine Sn nanoparticles uniformly embedded in shell of N-doped hollow carbon spheres is successfully synthesized by pyrolysis of the Sn 4+ -MOPs precursor. In this architecture, the N-doped carbon shells can effectively avoid the direct exposure of embedded Sn nanoparticles to the electrolyte and efficiently accommodate the volume change of Sn nanoparticles. Furthermore, the hollow structure of carbon sphere can prevent Sn nanoparticles aggregation over repeated cycling and shorten the diffusion path of both electrons and ions. As a consequence, this N-doped hollow Sn/C anode delivers a reversible capacity of 606 mA h g −1 at a current density of 0.2 A g −1 after 250 cycles and a reversible capacity of 221 mA h g −1 even at a much higher current density of 10 A g −1 , which are much better than those of pure Sn nanoparticles. The desirable cyclic stability and rate capability were attributed to the unique architecture that provided fast pathway for electron transport and simultaneously solved the major issues of Sn-based anodes, such as pulverization, aggregation and loss of electrical contact. [ABSTRACT FROM AUTHOR]

In order to mitigate the drastic volumetric expansion and maintain solid electrolyte interphase (SEI) stability of Sn anodes for lithium-ion battery, Sn/Ni@PEO bimetallic nanotube arrays are designed and fabricated. The Sn/Ni nanotube arrays grow directly on Cu foil by electrodeposition and a facile template based solution route, and further modify the surface by uniform PEO coating on the outer surface of the Sn/Ni nanotubes. Owing to the short lithium ion diffusion distance, high contact surface area, and very good structure stability of the nanotube arrays, the Sn/Ni@PEO nanotube arrays exhibit remarkable cyclic stability (approximate 806 mA h g −1 at 0.1 A g −1 after 200 cycles) and high power capability (a reversible capacity of 300 mA h g −1 at 2 A g −1 ). Such excellent electrochemical performance suggests that the Sn/Ni@PEO nanotube arrays can serve as a promising anode for lithium-ion batteries. [ABSTRACT FROM AUTHOR]

A novel polypyrrole (PPy) coated three-dimensional (3D) SnO 2 nanotube arrays (SnO 2 @PPy) is synthesized via a template-assisted method followed by a chemical vapor-phase polymerization process as a high performance anode for lithium-ion batteries. In this new type electrode material, the hollow interiors of SnO 2 are able to provide enough spaces for the accommodation of large volume expansion during the insertion of lithium-ion, making for the improvement of the stability of electrode. Meanwhile, the addition of conductive PPy layer could facilitate the electron transport, prevent the aggregation of active materials and warrant the stability of as-formed solid electrolyte interface (SEI) films. As a result, the integration of 3D hybrid nanostructure electrode is capable of retaining a high capacity of 646 mA h g −1 after 150 cycles with a coulomb efficiency above 98% and a capacity retention of 221 mA h g −1 even at a high current density of 5000 mA g −1 , revealing better cycling and rate properties compared with bare SnO 2 nanotube arrays anode. This nanoengineering strategy can provide a facile and controllable way to synthesize other anode materials for lithium-ion batteries. [ABSTRACT FROM AUTHOR]

Polymethyl methacrylate (PMMA)-coated hollow Sn–Co nanospheres (Sn–Co@PMMA) with superior electrochemical performance had been synthesized via a facile galvanic replacement method followed by an in situ emulsion polymerization route. The properties were investigated in detail and results show that the hollow Sn–Co nanospheres were evenly coated with PMMA. Benefiting from the protection of the PMMA layers, the hollow Sn–Co@PMMA nanocomposite is capable of retaining a high capacity of 590 mAh g −1 after 100 cycles with a coulomb efficiency above 98%, revealing better electrochemical properties compared with hollow Sn–Co anodes. The PMMA coating could help accommodate the mechanical strain caused by volume expansion and stabilize the solid electrolyte interphase (SEI) film formed on the electrode. Such a facile process could be further extended to other anode materials for lithium-ion batteries. [ABSTRACT FROM AUTHOR]

Abstract: Sn hollow nanospheres (HNSs) were prepared by galvanic replacement, employing Ni nanospheres (NSs) as templates. The formation process and electrochemical performance of Sn HNS were studied. The Sn HNS resulted in better stability and electrochemical performance when used as an anode material in lithium-ion batteries. The Sn HNS electrode retained a good reversible capacity of 516.1mAhg−1 after 50 cycles at a current density of 100mAhg−1, which was much higher than that of Sn NS (128mAhg−1). TEM images of the Sn HNSs after 50 cycles indicated that the volume expansion outside the spheres had been alleviated, and the aggregation between the active materials had been prevented. [Copyright &y& Elsevier]

Hollow SnO 2 nanosphere@TiO 2 yolk–shell hierarchical nanospheres (h-SnO 2 @TiO 2 YSHNSs) have been synthesized for the first time and evaluated as a high-performance anode material in lithium-ion batteries (LIBs). The h-SnO 2 @TiO 2 YSHNS anode exhibited high reversible capacity (~520 mA h g −1 at a current density of 100 mA g − 1 after 100 charge/discharge cycles), superior cyclic stability (capacity retention of ~63.3% after 100 cycles) and good rate performance (~172 mA h g −1 at 2400 mA g −1 ) due to the unique hierarchical yolk–shell nanostructure, comprised of a TiO 2 shell surrounding an interspace and the hollow SnO 2 yolk. These results suggest that the h-SnO 2 @TiO 2 YSHNS should be a promising anode candidate for next-generation LIBs. [ABSTRACT FROM AUTHOR]