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Transition metal oxides (TMOs) as anode materials have potential for lithium-ion batteries (LIBs). However, the poor rate capacity and cycle stability restrict its application. Herein, we demonstrate a facile one-step hydrothermal method to construct a three-dimensional porous conductive network structure, which consists of thin-layered graphene, ultrafine Co

Due to the intrinsic low electrical conductivity and large volume expansion of the CoFe

Transition metal oxides (TMOs) as anode materials have potential for lithium-ion batteries (LIBs). However, the poor rate capacity and cycle stability restrict its application. Herein, we demonstrate a facile one-step hydrothermal method to construct a three-dimensional porous conductive network structure, which consists of thin-layered graphene, ultrafine Co3O4-CoO nanoparticles and nitrogen-doped carbon. This unique structure can effectively prevent particle agglomeration and cracking caused by volume expansion, provide fast passage for lithium ion/electron transport during cycling and improve the electrical conductivity of the electrode. Moreover, the electrochemical kinetic analysis proves that this is a process dominated by pseudocapacitive behavior. Consequently, the N-C@Co3O4-CoO@GO hybrid electrode delivers an ultrahigh capacity of 1 273.1 mA h g-1 at 0.1 A g-1 and superior rate performance (725.1 mA h g-1 at 5 A g-1). Additionally, it exhibits a high reversible cycling capacity of 787.4 mA h g-1 at 1 A g-1 over 600 cycles and even maintains excellent cycling stability for a ultra-long cycles at 5 A g-1. This work provides a feasible strategy for fabricating the N-C@Co3O4-CoO@GO composite as a promising high-performance TMOs anode for LIBs.

Due to the intrinsic low electrical conductivity and large volume expansion of the CoFe2O4 based active materials, designing more novel structures is still one of the most important challenges for its lithium ion battery application. In this work, the CoFe2O4/reduced graphene oxide/carbon (CFO/rGO/C) composite with integrated multi-layer structure has been synthesized through a facial two-step hydrothermal method. Benefiting from the introduction of the graphene network and amorphous carbon coating layer, as well as the accompanying synergistic effect, this composite can exhibit fast and reversible lithium intercalation/deintercalation reactions. With the aid of a surface-induced capacitive process, the CFO/rGO/C composite delivers a superior specific capacity (945 mA h g-1 at 0.1 A g-1) and excellent long-term cyclic stability (421 mA h g-1 at 4 A g-1 with closely 100% Coulombic efficiency after 2000 cycles). Significantly, at a high current density of 1 A g-1, the reversible capacity exhibits a rapid increasing after 100 cycles and finally shows an ultra-high-capacity of 1430 mA h g-1 over 500 cycles. This method could be generalized to the preparation of other similar transition metal oxide-based materials for the development of high-performance energy storage systems.

To overcome inferior rate capability and cycle stability of MnO-based anode materials for lithium-ion batteries (LIBs), we reported a novel 3D porous MnO@GS/CNT composite, consisting of MnO nanoparticles homogeneously distributed on the conductive interconnected framework based on 2D graphene sheets (GS) and 1D carbon nanotubes (CNTs). The distinctive architecture offers highly interpenetrated network along with efficient porous channels for fast electron transfer and ionic diffusion as well as abundant stress buffer space to accommodate the volume expansion of the MnO nanoparticles. The MnO@GS/CNT anode exhibits an ultrahigh capacity of 1115 mAh g-1 at 0.2 A g-1 after 150 cycles and outstanding rate capacity of 306 mAh g-1 at 10.0 A g-1. Moreover, a stable capacity of 405 mAh g-1 after 3200 cycles can still be achieved, even at a large current density of 5.0 A g-1. When coupled with LiMn2O4 (LMO) cathode, the LMO [Formula: see text] MnO@GS/CNT full cell characterizes an excellent cycling stability and rate capability, indicating the promising application of MnO@GS/CNT anode in the next-generation LIBs.

A novel Ag@GQD (graphene quantum dot) hybrid fabricated by a facile two-step strategy is presented: the GQDs are prepared by citrate acid and AgNO3 is reduced. Catalytic studies showed that the Ag@GQD hybrid exhibited excellent photothermal effect and catalytic performance for 4-nitrophenol (4-NP) reduction, suggesting that the GQDs enhanced the catalytic activity via a synergistic effect and the Ag NPs boosted the catalytic efficiency through SPR-mediated photothermal local heating.