Puheng Yang

MOF-derived, N-doped porous carbon coated graphene sheets as high-performance anodes for lithium-ion batteries

N-doped porous carbon coated graphene (rGO) sheets (denoted as NPCGS) have been synthesized through a facile pyrolysis of an in situ grown zeolitic imidazolate framework (ZIF) on graphene oxide (GO). When tested as an anode material for lithium-ion batteries, the NPCGS exhibited superior electrochemical performance with a specific capacity of 1040 mA h g−1 after 200 cycles at a discharging current density of 0.5 A g−1 and excellent rate performance. The fascinating electrochemical performance of the NPCGS can be attributed to the synergistic effect of NPC and graphene in terms of N-doping, rich porosity and high electrical conductivity. The novel N-doped porous carbon coated graphene sheet material can be extended for application in sensors, electronic devices, catalysts, hydrogen storage and other systems.

Synthesis, structure and electrochemical properties of lithium-rich cathode material Li1.2Mn0.6Ni0.2O2 microspheres

Lithium-rich Li1.2Mn0.6Ni0.2O2 microspheres with a few mesopores have been successfully obtained. The results show that the Li1.2Mn0.6Ni0.2O2 material exhibits excellent cycling capability and rate performance. The microsphere morphology with a few mesopores could play a significant role in improving electrochemical performance.

Glucose-assisted combustion synthesis of Li1.2Ni0.13Co0.13Mn0.54O2 cathode materials with superior electrochemical performance for lithium-ion batteries

Lithium-rich layered Li1.2Ni0.13Co0.13Mn0.54O2 cathode materials have been successfully fabricated by a glucose-assisted combustion method combined with a calcination treatment. The effect of the amount of glucose fuel on the properties of the prepared materials is investigated by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy and electrochemical measurements. The results show that the nano-sized cathode material obtained at a fuel ratio of φ = 1 exhibits uniform fine well-crystallized particles with the largest specific surface area, leading to excellent cyclic capability and rate performance. It delivers the highest initial discharge capacity of 280.5 mA h g−1 with a capacity retention of 84% after 50 cycles at 0.1C (25 mA g−1). Besides, after cycling at an increasing rate from 0.2C to 3C, the electrode retained 90.3% (230.2 mA h g−1) of the initial discharge capacity when the rate was recovered back to 0.2C.

Investigation of Co3O4 nanorods supported Pd anode catalyst for methanol oxidation in alkaline solution

Abstract A Co 3 O 4 nanorod supported Pd electro-catalyst for the methanol electro-oxidation (MEO) has been fabricated by the combination of hydrothermal synthesis and microwave-assisted polyol reduction processes. The crystallographic property and microstructure have been characterized using XRD, SEM and TEM. The results demonstrate that Pd nanoparticles (PdNPs) with a narrow particle size distribution (3–5 nm) are uniformly deposited onto the surface of Co 3 O 4 nanorods. Electrochemical measurements show that this catalyst having a larger electrochemically active surface area and a more negative onset-potential exhibits enhanced catalytic activity of 504 mA/mg Pd for MEO comparing with the Pd/C catalyst (448 mA/mg Pd). The dependency of log I against log v reveals that MEO on Pd-Co 3 O 4 electrode is under a diffusion control. Electrochemical impedance spectroscopy (EIS) measurement agrees well with the CV results. The minimum charge transfer resistance of MEO on Pd-Co 3 O 4 is observed at −0.05 V, which coincides with the potential of MEO peak.

Rational design of a 3D MoS2/dual-channel graphene framework hybrid as a free-standing electrode for enhanced lithium storage

Integrating high-capacity MoS2 with carbon materials, especially graphene, into a rationally designed structure has been demonstrated an effective strategy to construct anode materials with superior electrochemical performance for application in lithium ion batteries (LIBs). Here, a rationally designed 3D MoS2/dual-channel graphene framework (MoS2/GA–GF) hybrid has been constructed through a two-step method. This dual-channel graphene framework (GA–GF) consists of two types of channels with different graphene types, graphene foam channels improving electron transport and graphene aerogel channels facilitating Li ion diffusion. With this structure, the MoS2/GA–GF hybrid can efficiently improve electron and Li ion transport kinetics and accommodate the MoS2 volume change during cycling. Benefiting from the above merits, the MoS2/GA–GF electrode as a free-standing electrode presents a high initial capacity (1404 mA h g−1) with a high initial coulombic efficiency (81.7%), excellent rate capability (593 mA h g−1 at 5 A g−1) and a superior long-term cycling stability (843 mA h g−1 at 1 A g−1 after 500 cycles) when evaluated as an LIB anode. Therefore, the GA–GF as a support and current collector is expected to be ideal for application in LIBs and other electrochemical energy storage devices.

Synthesis and properties of mesoporous Zn-doped Li1.2Mn0.54Co0.13Ni0.13O2 as cathode materials by a MOFs-assisted solvothermal method

Mesoporous nano-microparticles lithium-rich Zn-doped Li1.2Mn0.54Co0.13Ni0.13O2 cathode materials have been synthesized by utilizing the structural characteristics of metal–organic frameworks. The electrochemical performance is improved by the substitution of an appropriate amount of Zn into the layered Li-rich Li1.2Mn0.54Ni0.13Co0.13O2 cathode material.