Search

Metal oxide nanoparticles as the electrochemically active second phase were incorporated into the paper-like flexible graphene-based hybrid electrodes. Its size and dispersion are crucial factors for determining the rate capability and cycling stability of the flexible hybrid paper electrode. Herein, we employ in-situ formed ultrafine monodisperse TiO 2 quantum dots (QDs, ∼4.0 nm) as the electrochemically active second phase, which are uniformly incorporated into the flexible hybrid paper via a simple mixed solvothermal reaction together with a vacuum filtration, aiming at achieving a high-rate and long-cycle flexible TiO 2 -based anode in lithium ion batteries (LIBs). By combining the advantages of both ultrafine TiO 2 -QDs and three-dimensional (3D) conductive networks, the as-fabricated TiO 2 -QDs-reduced graphene oxide (TiO 2 -QDs-RGO) hybrid paper electrode shows high reversible capacity of 201 mA h g −1 after 100 cycles at 0.1 A g −1 and superior rate capability as well as long cycle life of 1500 cycles with ∼80.6% capacity retention at 2.0 A g −1 . Detailed electrochemical analysis shows that the improved capability and cyclability of the hybrid paper electrode results from the integrated intercalation-based and interfacial lithium storage behaviors as well as the 3D fast electron/ion transfer of materials, which is ascribed to the ultra-small size of TiO 2 -QDs and the 3D self-standing conductive networks of the hybrid paper electrode. The results demonstrate the distinct advantages of our material design strategy, and also might pave the way for further studies of other flexible metal oxide/graphene hybrid paper electrodes for fast and long-life flexible anodes in LIBs. [ABSTRACT FROM AUTHOR]

Hybrid hollow urchin-like cobalt and copper silicate constructed by nanotubes encapsulated in graphene nanosheets composites were successfully prepared using graphene oxide as carrier and silica spheres as template, which were done through a well-known Stȍber process and a hydrothermal method. In fact, the synthesis of hybrid urchin-like silicate constructed by nanotubes through onestep hydrothermal reaction has rarely been reported.The electrochemical performances of the composites as lithium-ion battery anode materials were studiedfor the first time. As novel anode materials of Li-ion batteries, the special hollow urchin-like structure not only could facilitate the Li + diffusion and electron transport but alsocouldaccommodate the volume variation during the conversion reactions. In addition, the introduction of graphene can make the electrical conductivity better. Graphene wrapped hollow urchin-like silicate compositespossesses superior electrochemical cycling properties. The first discharge capacity is1955.2mAh/g with a current density of 300 mA/g. The unique well-designed configuration presents a beneficial method to synthesize efficient and high performance electrode materials for advanced power applications. [ABSTRACT FROM AUTHOR]

Transition metal oxides are expected to replace commercial graphite for the next generation of secondary battery anode materials. However, the capacity decreases rapidly due to poor conductivity and volume expansion during operation. In this study, we first designed a yolk-shell structured ZnCo 2 O 4 sphere, and then combined it with reduced graphene oxide through an electrostatic interaction process. The prepared ZnCo 2 O 4 /RGO showed enhanced lithium/sodium storage performance. Specifically, it can provide 997.2 mA h g−1 (for LIBs, 500 cycles) and 280 mA h g−1 (for SIBs,1000 cycles) reversible capacities at 1.0 A g−1 current density, respectively. These superior properties are derived from their unique structure. On the one hand, the gap between the yolk and shells not only provides a shorter Li+/Na+ diffusion distance, but also the electrolyte can be in sufficient contact with the anode material to induce a rapid surface reaction; on the other hand, the introduction of graphene can effectively buffer the large volume expansion of the cycle and maintain the structural integrity of the electrode material. [ABSTRACT FROM AUTHOR]

Polyaniline (PANI) is one of the most attractive materials for pseudocapacitors. To enhance the electrolyte diffusion and improve the electrochemical performance of the electrode, the well-designed morphology of PANI is required. Incorporating carbon materials is also benefic on enhancing the cycling stability as well as the mechanical and electrochemical properties of PANI. In this study, a simple solution method is applied to synthesize the particle-deposited tube-like PANI. Due to the well-defined structure, a specific capacitance (C F ) of 437.8 F/g is achieved at the current density of 4 A/g. Furthermore, the self-synthesized graphene oxide (GO) is simply mixed with the particle-deposited tube-like PANI to make a more efficient electrocapacitive material. An enhanced C F value of 475.0 F/g is achieved for the optimized PANI/GO electrode, owing to the synergic effects of the pseudo-capacitance from PANI and the functional groups of GO, as well as the electrochemical double-layered capacitance from GO. After conducting 2000 cycles repeated charge/discharge process, the C F retention of 90% and the average Coulombic efficiency of higher than 90% are also attained for the optimized PANI/GO electrode. [ABSTRACT FROM AUTHOR]