Enhancing the adsorption and catalytic conversion of polysulfides by nitrogen doped carbon micro-flowers embedded with Mo2C nanoparticles

摘要

Synthesis of hybrid architectures for sulfur host materials has been certificated as an efficient way to enhance the performances of lithium-sulfur (LieS) batteries owing to the generated synergetic effects from each component. However, it remains challenging to construct hybrid nanostructures with reasonable structure and rational composition to achieve high-performance of LieS batteries. Here, a coordinated nanostructure constituted of the Mo2C nanoparticles embedded in the micro-flowered high content N-doped (11.73 at.%) carbon substrate (Mo2C@NC) is synthesized via using protonated g-C3N4 as the template, which is used as the sulfur host for LieS batteries. Owing to the physical entrapment from the porous carbon substrate with special micro-flower morphology, and the synergistic chemisorption from pyridine N sites and polar Mo2C nanoparticles, the as-prepared Mo2C@NC can afford a high content of sulfur loading and enables fast/reliable sulfur electrochemistry. Given these, the Mo2C@NC based cathode with a high sulfur content of 76% delivers a high initial discharge capacity of 1403.7 mAh g(-1) at 0.1 C. Even at a high rate of 2.0 C, it still shows desirable electrochemical performances with an initial capacity of 910.6 mAh g(-1) and superb cycling stability with an average capacity decay rate of only 0.001% per cycle over 500 cycles. Moreover, upon a high sulfur loading of 5.5 mg cm(-2), the Mo2C@NC/S cathode can still maintain decent sulfur related electrochemistry and achieves a high areal capacity of 5.56 mAh cm(-2) with excellent stability. It is expected this work provides a new perspective to the rational design of conductive and polar material that suitable for high-efficiency and long-lasting LieS batteries.

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