高吡啶氮含量的氮掺杂蜂窝状碳促进对多硫化物的限制以实现高性能锂硫电池

Facilitating polysulfide confinement using N-doped honeycomb-like carbon with high pyridinic-nitrogen content for high-performance Li-S batteries

提高碳材料中氮的掺杂含量,尤其是吡啶氮的含量,已被证明可以显著提升锂硫(Li-S)电池的性能.尽管在碳材料中氮掺杂具有积极作用,但在实际操作中要实现>5 at.%的高氮掺杂含量仍非易事.此外,无法调节碳材料中特定的氮种类也是研究中的一个难题.在本文中,我们通过在氩气气氛下煅烧预先经过磷化处理的泛酸钙,得到了一种三维蜂窝状的氮(N)掺杂介孔碳(PNMC),其N掺杂含量高达8.82 at.%(吡啶N含量为3.49 at.%).磷掺杂不仅有助于提高N掺杂量,还有助于提升对多硫化物的吸附能力.实验证明,在800℃下制备的PNMC组装的硫正极(S/PNMC-800)表现出优异的电化学性能,在1 C下经过300圈循环后仍有556.7 mA h g^(-1)放电比容量.本工作提出了一种调控碳材料中吡啶氮含量的简便方法,为用于锂硫电池的多功能硫载体材料的开发提供启发.

Increasing the amount of the nitrogen dopant,especially pyridinic-N species,in carbonaceous materials has been shown to significantly enhance the performance of lithium-sulfur(Li-S)batteries.Despite the positive impact of N doping on carbonaceous materials,the practical realisation of a high N dopant content of5 at.%remains a significant challenge.Furthermore,to regulate the specific N species in carbonaceous materials is another hurdle.Herein,we obtained a three-dimensional honeycomb-like N-doped mesoporous carbon(PNMC)material with a high N dopant content of 8.82 at.%(pyridinic-N content,3.49 at.%)by calcining calcium pantothenate under an Ar atmosphere after a phosphorisation process.It is believed that the P dopant contributes to the enhancement of not only the N content but also the polysulfide adsorption capability of the N dopant.As expected,the sulfur cathode comprising PNMC prepared at 800℃(S/PNMC-800)exhibited superior electrochemical performance as confirmed by the discharge specific capacity of 556.7 mA h g^(-1)observed after 300 cycles at 1 C.This study proposes a facile regulation technique to dope pyridinic-N species in carbonaceous materials,which may trigger the future inventive development of functional S hosts for use in Li-S batteries.