Zhigao Luo

Two-dimensional hybrid nanosheets of few layered MoSe2 on reduced graphene oxide as anodes for long-cycle-life lithium-ion batteries

A rational design of two-dimensional (2D) hybrid materials between transition metal dichalcogenides (TMDs) and graphene has received great attention because of their promising applications in the energy field. Herein, we report the synthesis of novel 2D hybrid nanosheets constructed by few layered MoSe2 grown on reduced graphene oxide (rGO). As a proof-of-concept application, the 2D MoSe2/rGO nanosheets exhibit excellent electrochemical performance as anodes for lithium ion batteries, demonstrating outstanding cycling stability (up to 1000 cycles), and high-rate capability.

Nanorod-Nanoflake Interconnected LiMnPO4·Li3V2(PO4)3/C Composite for High-Rate and Long-Life Lithium-Ion Batteries

Olivine-type structured LiMnPO4 has been extensively studied as a high-energy density cathode material for lithium-ion batteries. However, preparation of high-performance LiMnPO4 is still a large obstacle due to its intrinsically sluggish electrochemical kinetics. Recently, making the composites from both active components has been proven to be a good proposal to improve the electrochemical properties of cathode materials. The composite materials can combine the advantages of each phase and improve the comprehensive properties. Herein, a LiMnPO4·Li3V2(PO4)3/C composite with interconnected nanorods and nanoflakes has been synthesized via a one-pot, solid-state reaction in molten hydrocarbon, where the oleic acid functions as a surfactant. With a highly uniform hybrid architecture, conductive carbon coating, and mutual cross-doping, the LiMnPO4·Li3V2(PO4)3/C composite manifests high capacity, good rate capability, and excellent cyclic stability in lithium-ion batteries. The composite electrodes deliver a high reversible capacity of 101.3 mAh g-1 at the rate up to 16 C. After 4000 long-term cycles, the electrodes can still retain 79.39% and 72.74% of its maximum specific discharge capacities at the rates of 4C and 8C, respectively. The results demonstrate that the nanorod-nanoflake interconnected LiMnPO4·Li3V2(PO4)3/C composite is a promising cathode material for high-performance lithium ion batteries.

Metal-organic framework-derived porous shuttle-like vanadium oxides for sodium-ion battery application

Vanadium oxides with a layered structure are promising candidates for both lithium-ion batteries and sodium-ion batteries (SIBs). The self-template approach, which involves a transformation from metal-organic frameworks (MOFs) into porous metal oxides, is a novel and effective way to achieve desirable electrochemical performance. In this study, porous shuttle-like vanadium oxides (i.e., V2O5, V2O3/C) were successfully prepared by using MIL-88B (V) as precursors with a specific calcination process. As a proof-of-concept application, the asprepared porous shuttle-like V2O3/C was used as an anode material for SIBs. The porous shuttle-like V2O3/C, which had an inherent layered structure with metallic behavior, exhibited excellent electrochemical properties. Remarkable rate capacities of 417, 247, 202, 176, 164, and 149 mAh·g−1 were achieved at current densities of 50, 100, 200, 500, 1,000, and 2,000 mA·g−1, respectively. Under cycling at 2 A·g−1, the specific discharge capacity reached 181 mAh·g−1, with a low capacity fading rate of 0.032% per cycle after 1,000 cycles. Density functional theory calculation results indicated that Na ions preferred to occupy the interlamination rather than the inside of each layer in the V2O3. Interestingly, the special layered structure with a skeleton of dumbbell-like V–V bonds and metallic behavior was maintained after the insertion of Na ions, which was beneficial for the cycle performance. We consider that the MOF precursor of MIL-88B (V) can be used to synthesize other porous V-based materials for various applications.

Encapsulation of CoS x Nanocrystals into N/S Co-Doped Honeycomb-Like 3D Porous Carbon for High-Performance Lithium Storage

Abstract A honeycomb‐like 3D N/S co‐doped porous carbon‐coated cobalt sulfide (CoS, Co9S8, and Co1– xS) composite (CS@PC) is successfully prepared using polyacrylonitrile (PAN) as the nitrogen‐containing carbon source through a facile solvothermal method and subsequent in situ conversion. As an anode for lithium‐ion batteries (LIBs), the CS@PC composite exhibits excellent electrochemical performance, including high reversible capacity, good rate capability, and cyclic stability. The composite electrode delivers specific capacities of 781.2 and 466.0 mAh g−1 at 0.1 and 5 A g−1, respectively. When cycled at a current density of 1 A g−1, it displays a high reversible capacity of 717.0 mAh g−1 after 500 cycles. The ability to provide this level of performance is attributed to the unique 3D multi‐level porous architecture with large electrode–electrolyte contact area, bicontinuous electron/ion transport pathways, and attractive structure stability. Such micro‐/nanoscale design and engineering strategies may also be used to explore other nanocomposites to boost their energy storage performance.

Caging Na3V2(PO4)2F3 Microcubes in Cross-Linked Graphene Enabling Ultrafast Sodium Storage and Long-Term Cycling

Abstract Sodium‐ion batteries are widely regarded as a promising supplement for lithium‐ion battery technology. However, it still suffers from some challenges, including low energy/power density and unsatisfactory cycling stability. Here, a cross‐linked graphene‐caged Na3V2(PO4)2F3 microcubes (NVPF@rGO) composite via a one‐pot hydrothermal strategy followed by freeze drying and heat treatment is reported. As a cathode for a sodium‐ion half‐cell, the NVPF@rGO delivers excellent cycling stability and rate capability, as well as good low temperature adaptability. The structural evolution during the repeated Na+ extraction/insertion and Na ions diffusion kinetics in the NVPF@rGO electrode are investigated. Importantly, a practicable sodium‐ion full‐cell is constructed using a NVPF@rGO cathode and a N‐doped carbon anode, which delivers outstanding cycling stability (95.1% capacity retention over 400 cycles at 10 C), as well as an exceptionally high energy density (291 Wh kg−1 at power density of 192 W kg−1). Such micro‐/nanoscale design and engineering strategies, as well as deeper understanding of the ion diffusion kinetics, may also be used to explore other micro‐/nanostructure materials to boost the performance of energy storage devices.