Li2S is one of the most promising cathode materials for Li‐ion batteries because of its high theoretical capacity and compatibility with Li‐metal‐free anode materials. However, the poor conductivity and electrochemical reactivity lead to low initial capacity and severe capacity decay. In this communication, a nitrogen and phosphorus codoped carbon (N,P–C) framework derived from phytic acid doped polyaniline hydrogel is designed to support Li2S nanoparticles as a binder‐free cathode for Li–S battery. The porous 3D architecture of N and P codoped carbon provides continuous electron pathways and hierarchically porous channels for Li ion transport. Phosphorus doping can also suppress the shuttle effect through strong interaction between sulfur and the carbon framework, resulting in high Coulombic efficiency. Meanwhile, P doping in the carbon framework plays an important role in improving the reaction kinetics, as it may help catalyze the redox reactions of sulfur species to reduce electrochemical polarization, and enhance the ionic conductivity of Li2S. As a result, the Li2S/N,P–C composite electrode delivers a stable capacity of 700 mA h g−1 with average Coulombic efficiency of 99.4% over 100 cycles at 0.1C and an areal capacity as high as 2 mA h cm−2 at 0.5C.
Lithium-sulfur batteries are considered as a promising candidate for high energy density storage applications. However, their specific capacity and cyclic stability are hindered by poor conductivity of sulfur and the dissolution of redox intermediates. Here, we design polypyrrole-MnO coaxial nanotubes to encapsulate sulfur, in which MnO restrains the shuttle effect of polysulfides greatly through chemisorption and polypyrrole serves as conductive frameworks. The polypyrrole-MnO nanotubes are synthesized through in situ polymerization of pyrrole using MnO nanowires as both template and oxidization initiator. A stable Coulombic efficiency of ∼98.6% and a decay rate of 0.07% per cycle along with 500 cycles at 1C-rate are achieved for S/PPy-MnO ternary electrodes with 70 wt % of S and 5 wt % of MnO. The excellent trapping ability of MnO to polysulfides and tubular structure of polypyrrole with good flexibility and conductivity are responsible for the significantly improved cyclic stability and rate capability.
In this work, hierarchically porous NiO/C microspheres were successfully synthesized via a facile biotemplating method using natural porous lotus pollen grains as both the carbon source and the template. The as-prepared hierarchically porous NiO/C microspheres exhibited a large specific surface area and multiple pore size distribution, which could effectively increase the electrochemical reaction area and allow better penetration of the electrolyte. The Raman results also confirmed that the pollen grains have been well carbonized, which could provide good electronic conductivity. The specific capacities of the porous NiO/C microspheres after every 10 cycles at 0.1, 0.5, 1, and 3 A g À1 are about 698, 608, 454 and 352 mAh g À1 . As an anode material in a Li ion half-cell, these unique hybrid hierarchically porous NiO/C microspheres exhibited fascinating electrochemical performance.
Porous Pt nanostructure decorated sulfur microparticles (Pt@S) are fabricated using sulfur as the template. The Pt@S electrode shows a higher volumetric specific capacity of 520 mA h cm(-3) and improved cyclability with only 15% capacity fading after 80 cycles at 0.1 C (167.5 mA g(-1)).
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