Mingzhong Zou

An efficient bifunctional catalyst of Fe/Fe3C carbon nanofibers for rechargeable Li–O2 batteries

Designing an efficient catalyst is essential to improve the electrochemical performance for Li–O2 batteries. In this study, the novel composites of Fe/Fe3C carbon nanofibers (Fe/Fe3C–CNFs) were synthesized via a facile electrospinning method and used as cathode catalysts for Li–O2 batteries. Owing to their favorable structures and desirable bifunctional catalytic activities, the resulting cathodes with a Fe/Fe3C–CNF catalyst exhibited superior electrochemical performance with high specific capacity, good rate capability and cycle stability. It is revealed that the synergistic effect of the fast kinetics of electron transport provided by the CNF support and the high electro-catalytic activity provided by the Fe/Fe3C composites resulted in the excellent performance for Li–O2 batteries. The preliminary result manifests that the composites of Fe/Fe3C–CNFs are promising cathode electrocatalysts for Li–O2 batteries.

An effective integrated design for enhanced cathodes of Ni foam-supported Pt/carbon nanotubes for Li-O2 batteries.

Designing an effective microstructural cathode combined with a highly efficient catalyst is essential for improving the electrochemical performance of Li-O2 batteries (LOBs), especially for long-term cycling. We present a nickel foam-supported composite of Pt nanoparticles (NPs) coated on self-standing carbon nanotubes (CNTs) as a binder-free cathode for LOBs. The assembled LOBs can afford excellent electrochemical performance with a reversible capacity of 4050 mAh/g tested at 20 mA/g and superior cyclability for 80 cycles with a limited capacity of 1500 mAh/g achieved at a high current density of 400 mA/g. The capacity corresponds to a high energy density of ∼3000 Wh/kg. The improved performance should be attributed to the excellent catalytic activity of highly dispersed Pt NPs, facile electron transport via loose CNTs connected to the nickel foam current collector, and fast O2 diffusion through the porous Pt/CNTs networks. In addition, some new insights from impedance analysis have been proposed to explain the enhanced mechanism of LOBs.

Nano-crystalline FeOOH mixed with SWNT matrix as a superior anode material for lithium batteries

Nano-crystalline FeOOH particles (5∼10 nm) have been uniformly mixed with electric matrix of single-walled carbon nanotubes (SWNTs) for forming FeOOH/SWNT composite via a facile ultrasonication method. Directly using the FeOOH/SWNT composite (containing 15 wt% SWNTs) as anode material for lithium battery enhances kinetics of the Li+ insertion/extraction processes, thereby effectively improving reversible capacity and cycle performance, which delivers a high reversible capacity of 758 mAh·g−1 under a current density of 400 mA·g−1 even after 180 cycles, being comparable with previous reports in terms of electrochemical performance for FeOOH anode. The good electrochemical performance should be ascribed to the small particle size and nano-crystalline of FeOOH, as well as the good electronic conductivity of SWNT matrix.

A simple integrated design and manufacture by electrospinning of stabilized lithium battery tin-based anodes

Self-standing papers of N-doped carbon nanofibers loaded with SnCu–SnOx materials have been integratively prepared by electrospinning and directly used as anodes for lithium ion batteries. These anodes afford an excellent electrochemical performance with a reversible capacity of 470 mA h g−1 tested at 200 mA g−1 after 100 cycles.

NiSnO3 nanoparticles/reduced graphene oxide composite with enhanced performance as a lithium-ion battery anode material

NiSnO3 nanoparticles (NPs) were loaded on reduced graphene oxide (RGO) by a facile hydrothermal technique as a anode material for lithium ion batteries (LIBs). It was found that the NiSnO3/RGO anode exhibits improved LIBs performance compared to bare NiSnO3 or RGO. The NiSnO3/RGO anode can maintain a reversible capacity of 792 mA h g−1, tested at 1200 mA g−1 after 60 cycles. When the current density was lowered in a test of rate capacity, the charge capacity was completely restored after high rate cycling at 6000 mA g−1 and maintained 889 mA h g−1 at 200 mA g−1 after 115 cycles. The enhanced LIBs performance of the NiSnO3/RGO nanocomposites can be attributed to the synergistic effects between a highly loaded NiSnO3 NPs and graphene network.

Iron encapsulated in single-walled carbon nanotubes for obtaining the evidence of improved coulombic efficiency and improving the lithium battery performance of ZnO anodes

Cycling coulombic efficiency including the 1st cycle is a crucial factor for nano-carbon based anodes. How to improve their coulombic efficiency and further prove whether the additional reversible capacity produced from the SEI film in the 1st cycle is an obstacle for their possible commercial application in Li ion batteries (LIBs). For this aim, a novel composite of Fe-encapsulated single-walled carbon nanotubes (Fe@SWNTs) with special nano-structure was designed and used as an anode material for LIBs. The resulting Fe@SWNT anode can provide much larger coulombic efficiency of 53.1% in the 1st cycle than 35.6% for pure SWNTs, implying the value increment reached ∼50%. The Fe@SWNTs can exhibit an reversible capacity of 420 mA h g−1 after 300 cycles and excellent rate performance at room temperature, being obviously better than 275 mA h g−1 for a SWNT anode. The origination of this extra improved reversible capacity can be confirmed to be derived from the reversible reaction of SEI film activated by the Fe catalyst. Meanwhile, the Fe@SWNT anodes exhibited superior low-temperature (at 5 and −15 °C) electrochemical performance, which should be associated with an improved effect of the highly conducting Fe at low temperature, and with the activation of catalyst Fe on the reversible capacity. In addition, when Fe@SWNTs were developed as carriers for attaching ZnO, the ZnO/Fe@SWNTs can deliver much better LIB performance than anodes of pure ZnO and ZnO/SWNTs. Thus, catalyst modification supplied a promising route to obtain improved coulombic efficiency and reversible capacity for LIB nano-carbon based anodes.