Lichun Yang

Sandwich-Stacked SnO2/Cu Hybrid Nanosheets as Multichannel Anodes for Lithium Ion Batteries

We have introduced a facile strategy to fabricate sandwich-stacked SnO2/Cu hybrid nanosheets as multichannel anodes for lithium-ion batteries applying rolled-up nanotechnology with the use of carbon black as intersheet spacer. By employing a direct self-rolling and compressing approach, a much higher effective volume efficiency is achieved as compared to rolled-up hollow tubes. Benefiting from the nanogaps formed between each neighboring sheet, electron transport and ion diffusion are facilitated and SnO2/Cu nanosheet overlapping is prevented. As a result, the sandwich-stacked SnO2/Cu hybrid nanosheets exhibit a high reversible capacity of 764 mAh g(-1) at 100 mA g(-1) and a stable cycling performance of ~75% capacity retention at 200 mA g(-1) after 150 cycles, as well as a superior rate capability of ~470 mAh g(-1) at 1 A g(-1). This synthesis approach presents a promising route to design multichannel anodes for high performance Li-ion batteries.

Sandwich-like SnS/Polypyrrole Ultrathin Nanosheets as High-Performance Anode Materials for Li-Ion Batteries.

Sandwich-like SnS/polypyrrole ultrathin nanosheets were synthesized via a pyrrole reduction and in situ polymerization route, in which room-temperature synthesized ZnSn(OH)6 microcubes were used as the tin source. As anode materials for Li-ion batteries, they exhibit an extremely high reversible capacity (about 1000 mA h g(-1) at 0.1C), outstanding rate capability (with reversible capabilities of 878, 805, 747, 652, and 576 mA h g(-1) at 0.2C, 0.5C, 1C, 2C, and 5C, respectively), stable cycling performance, and high capacity retention (a high capacity of 703 mA h g(-1) at 1C after long 500 cycles).

Metal–Organic Framework-Derived NiSb Alloy Embedded in Carbon Hollow Spheres as Superior Lithium-Ion Battery Anodes

The MOFs (metal-organic frameworks) have been extensively used for electrode materials due to their high surface area, permanent porosity, and hollow structure, but the role of antimony on the MOFs is unclear. In this work, we design the hollow spheres Ni-MOFs with SbCl3 to synthesize NiSb⊂CHSs (NiSb-embedded carbon hollow spheres) via simple annealing and galvanic replacement reactions. The NiSb⊂CHSs inherited the advantages of Ni-MOFs with hollow structure, high surface area, and permanent porosity, and the NiSb nanoparticles are coated by the formed carbon particles which could effectively solve the problem of vigorous volume changes during the Li+ insertion/extraction process. The porous and network structure could well provide an extremely reduced pathway for fast Li+ diffusion and electron transport and provide extra free space for alleviating the structural strain. The NiSb⊂CHSs with these features were used as Li-ion batteries for the first time and exhibited excellent cycling performance, high specific capacity, and great rate capability. When coupled with a nanostructure LiMn2O4 cathode, the NiSb⊂CHSs//LiMn2O4 full cell also characterized a high voltage operation of ≈3.5 V, high rate capability (210 mA h g-1 at a current density of 2000 mA g-1), and high Coulombic efficiency of approximate 99%, meeting the requirement for the increasing demand for improved energy devices.

Facile synthesis of Ge@FLG composites by plasma assisted ball milling for lithium ion battery anodes

Efficient production of graphene or its germanium (Ge) composites remains a challenge, although Ge nanoparticles (NPs) wrapped with graphene are suitable for preventing the large volume change of anodes for lithium ion batteries during Li uptake and release processes. This work is the first simple, efficient in situ synthesis of Ge NPs, with an excellent structure, wrapped with few-layer graphene sheets (abbreviated as Ge@FLG) from commercial Ge powders and natural graphite by a one-step ball-milling process assisted by dielectric-barrier discharge plasma. Because of their unique structure, Ge@FLG electrodes exhibit better electrical conductivity, low initial capacity loss, good cycling capability, and rate resilience compared with Ge@C electrodes prepared by conventional milling. This work highlights a new method for the efficient production of Ge@FLG composites and their applications in lithium ion batteries and in other technologies.

Microwave-Assisted Reactant-Protecting Strategy toward Efficient MoS2 Electrocatalysts in Hydrogen Evolution Reaction

The exposure of rich active sites is crucial for MoS2 nanocatalysts in efficient hydrogen evolution reaction (HER). However, the active (010) and (100) planes tend to vanish during preparation because of their high surface energy. Employing the protection by thiourea (TU) reactant, a microwave-assisted reactant-protecting strategy is successfully introduced to fabricate active-site-rich MoS2 (AS-rich MoS2). The bifunctionality of TU, as both a reactant and a capping agent, ensures rich interactions for the effective protection and easy exposure of active sites in MoS2, avoiding the complicated control and fussy procedure related to additional surfactants and templates. The as-obtained AS-rich MoS2 presents the superior HER activity characterized by its high current density (j = 68 mA cm(-2) at -300 mV vs RHE), low Tafel slope (53.5 mV dec(-1)) and low onset overpotential (180 mV), which stems from the rich catalytic sites and the promoted conductivity. This work elucidates a feasible way toward high performance catalysts via interface engineering, shedding some light on the development of emerging nanocatalysts.

Mesoporous Mo2C/N-doped carbon heteronanowires as high-rate and long-life anode materials for Li-ion batteries

Transition metal carbides are an emerging class of anode materials for Li-ion batteries (LIBs), which have recently drawn attention because of their good conductivity and high capacity after rational nano-engineering. In this work, we have developed Mo2C/N-doped carbon mesoporous heteronanowires (Mo2C/N–C MHNWs) with enhanced capacitive behaviour as high-performance anode materials for LIBs. With the heterostructure, the Mo2C nanocrystallites offer short paths for Li+ diffusion, while the N-doped carbon matrix facilitates fast electron transportation and buffers the volume change of Mo2C during the discharge/charge cycles. When evaluated as anodes for LIBs, the Mo2C/N–C MHNWs exhibited high capacity and high rate capability, as well as a long-term cycle life. In particular, a reversible capacity of 744.6 mA h g−1 was achieved in the first cycle, and 732.9 mA h g−1 was preserved after 700 cycles at a current density of 2 A g−1. The outstanding performance stems from fast kinetics enhanced by the pseudocapacitive effect, which was evidenced in the further analysis based on electrochemical impedance spectra and cyclic voltammetry. Our results elucidate the attractive Li+ storage performance of Mo2C-based nanocomposites, which may shed some light on the development of high-performance materials for energy storage and utilization.

Ilmenite Nanotubes for High Stability and High Rate Sodium-Ion Battery Anodes

To solve the problem of large volume change and low electronic conductivity of earth-abundant ilmenite used in rechargeable Na-ion batteries (SIBs), an anode of tiny ilmenite FeTiO3 nanoparticle embedded carbon nanotubes (FTO⊂CNTs) has been successfully proposed. By introducing a TiO2 shell on metal-organic framework (Fe-MOF) nanorods by sol-gel deposition and subsequent solid-state annealing treatment of these core-shell Fe-MOF@TiO2, such well-defined FTO⊂CNTs are obtained. The achieved FTO⊂CNT electrode has several distinct advantages including a hollow interior in the hybrid nanostructure, fully encapsulated ultrasmall electroactive units, flexible conductive carbon matrix, and stable solid electrolyte interface (SEI) of FTO in cycles. FTO⊂CNT electrodes present an excellent cycle stability (358.8 mA h g-1 after 200 cycles at 100 mA g-1) and remarkable rate capability (201.8 mA h g-1 at 5000 mA g-1) with a high Coulombic efficiency of approximately 99%. In addition, combined with the typical Na3V2(PO4)3 cathode to constitute full SIBs, the assembled FTO⊂CNT//Na3V2(PO4)3 batteries are also demonstrated with superior rate capability and a long cycle life.

Hierarchical MoO2/Mo2C/C Hybrid Nanowires as High-Rate and Long-Life Anodes for Lithium-Ion Batteries

Hierarchical MoO2/Mo2C/C hybrid nanowires (MoO2/Mo2C/C HNWs) have been fabricated through facile calcination of Mo3O10(C6H5NH3)2·2H2O nanowires which serve as both precursors and self-templates. In the MoO2/Mo2C/C HNWs, nanoparticles dispersed in the nanowires are beneficial for Li(+) transportation due to the decreased diffusion paths. Moreover, hybridization with Mo2C and carbon facilitates the electron transfer and increases the structural stability without sacrifice of capacity. As anode materials for lithium-ion batteries, the MoO2/Mo2C/C HNWs exhibit a reversible capacity of 950 mA h g(-1) after 320 cycles at a current density of 200 mA g(-1). Even when cycled at 2000 mA g(-1), they maintained a reversible capacity of 602 mA h g(-1) after 500 cycles. By incorporation of Mo2C and C with MoO2, the MoO2/Mo2C/C HNWs show high-rate capability and long cycle life and can be a promising candidate for lithium-ion battery anodes.

Deformable fibrous carbon supported ultrafine nano-SnO2 as a high volumetric capacity and cyclic durable anode for Li storage

Multidimensional fibrous carbon scaffolds, derived from carbonized filter papers (CFPs), were used to support SnO2 nanocrystals (NCs, with a size of 4–5 nm) to form a free-standing SnO2NC@CFP hybrid anode for Li-ion batteries. The SnO2NC particles are well accreted on the surfaces of 1D carbon fibers and 2D ultrathin carbon sheets while maintaining 3D interconnected pores of the carbon matrices for fast ionic transport. The SnO2NC@CFP hybrid electrode exhibits long-term higher energy density than the commercial graphite anode, and excellent rate capability, mainly due to good dispersion of SnO2 in the multidimensional conductive carbon. In particular, the reversible deformation of the flexible fibrous carbon matrices, as inferred from in situ Raman spectroscopy and SEM image analysis, facilitates stress release from the active SnO2NCs during discharge–charge cycling while maintaining the structural integrity of the self-supported SnO2NC@CFP anode. These demonstrate that the rational combination of the multidimensional architecture of deformable carbon with nanoscale active materials is ideally suited for high-performance Li-ion batteries.

Dynamic Molecular Processes Detected by Microtubular Opto-chemical Sensors Self-Assembled from Prestrained Nanomembranes

Libo Ma , * Shilong Li , Vladimir A. Bolanos Quinones , Lichun ang , Y Wang Xi , Matthew Jorgensen , Stefan Baunack , ongfeng Y Mei , Suwit Kiravittaya , and Oliver G. Schmidt