Huali Wu

A high-efficiency N/P co-doped graphene/CNT@porous carbon hybrid matrix as a cathode host for high performance lithium–sulfur batteries

Heteroatom-doped carbon hybrids containing sp2-hybridized and sp3-hybridized nanocarbons have attracted immense interest as sulfur hosts due to their unique 3D conductive networks and synergistic effect of physical absorption and chemical interaction on suppressing the dissolution of polysulfides. However, the reported carbon hybrids always require a tedious fabrication process, including multistep chemical vapor deposition and a thermally stable catalyst. Therefore, it is highly desirable to exploit a simple, renewable, and scalable strategy to fabricate 3D heteroatom-doped carbon hybrids. Herein, a N, P-co-doped 3D carbon hybrid was successfully fabricated via a one-pot pyrolysis process. Due to the rapid Li+/e− transport among the 3D interconnected porous frameworks and effectively suppressed polysulfide dissolution by physical confinement and chemical interaction, the assembled Li–S batteries exhibit excellent electrochemical performance. The as-obtained cell delivers an ultrahigh initial discharge capacity of 1446 mA h g−1 at 0.1C as well as an excellent rate capability of 921 mA h g−1 at 1C. Additionally, a reversible and stable discharge capacity of 795 mA h g−1 is maintained after 400 cycles at 1C, corresponding to an extremely low capacity decay of 0.034% per cycle. Such a design strategy is eco-friendly and generally applicable to combine the sp2 nanocarbon with sp3 amorphous carbon, which is crucial to construct 3D interconnected hierarchical porous carbons for advanced energy storage for applications in various fields, such as lithium batteries, catalysis and hydrogen storage.

Enhanced cycling stability and rate capability of Bi2O3-coated Li1.2Mn0.54Ni0.13Co0.13O2 cathode materials for lithium-ion batteries

Li-rich layered oxide of Bi2O3-coated Li1.2Mn0.54Ni0.13Co0.13O2 was fabricated via a combined method of sol–gel and wet chemical coating processes. The crystal structure of Li1.2Mn0.54Ni0.13Co0.13O2 has no obvious change after the coating of 2 wt% Bi2O3. Bi2O3 is homogenously coated on the surface of Li1.2Mn0.54Ni0.13Co0.13O2 particles. The Bi2O3-coated Li1.2Mn0.54Ni0.13Co0.13O2 electrode presents an enhanced cycling stability, better rate performance and lower charge transfer resistance. After the coating of 2 wt% Bi2O3, the initial coulombic efficiency of the material has been improved to 76.9% compared to 72.6% for the bare Li1.2Mn0.54Ni0.13Co0.13O2. After 100 cycles at 0.1C, the Bi2O3-coated Li1.2Mn0.54Ni0.13Co0.13O2 electrode retains a discharge capacity of 182.9 mA h g−1 with capacity retention of 73.5%, which are much higher than those of Li1.2Mn0.54Ni0.13Co0.13O2 (146.9 mA h g−1 and 58.8%). In addition, the Bi2O3-coated Li1.2Mn0.54Ni0.13Co0.13O2 electrode exhibits better rate capability with discharge capacities of 155.8, 124.8 and 89.2 mA h g−1 at 1, 2 and 5C, respectively, superior to that of Li1.2Mn0.54Ni0.13Co0.13O2. The enhanced cycling stability and rate capability should be ascribed to the existence of Bi2O3 on the surface of the active material, which can efficiently restrain the side reactions between the electrode and electrolyte, stabilize the structure of Li1.2Mn0.54Ni0.13Co0.13O2 and improve the lithium ion diffusion.

A sustainable hierarchical carbon derived from cultivated fibroid fungus for high performance lithium–sulfur batteries

Biomass plays an important role in constructing carbon materials, but is always restricted by the non-tunable and non-standard characteristics of its precursors. In this study, we employed a new sustainable microorganism-route to synthesize the fibroid fungus that could be used as the precursor to prepare sulfur host materials for lithium sulfur batteries. The H3PO4-activated fibroid fungus presents a controllable nano- and micro-structure after high temperature carbonization, which can effectively suppress polysulfides dissolution and supply space for sulfur accommodation due to its high specific surface area of 509 m2 g−1 and pore volume of 0.69 m3 g−1. As a result, the assembled lithium sulfur (Li–S) battery shows a high initial specific discharge capacity of 1319 mA h g−1 at 0.1C and maintains a capacity of 663 mA h g−1 after 100 cycles, corresponding to the outstanding reaction kinetics and cycling stability. Our results display an eco-friendly, renewable and controlled synthesis process of porous carbon, which features a promising application in preparing versatile electrodes in energy storage.