Cha Wangsoo, Kim In Young, Lee Jang Mee, Kim Sungho, Ramadass Kavitha, Gopalakrishnan Kothandam, Premkumar Selvarajan, Umapathy Siva, Vinu Ajayan
Global Innovative Center for Advanced Nanomaterials (GICAN), School of Engineering Faculty of Engineering and Built Environment , The University of Newcastle , Callaghan , New South Wales 2308 , Australia.
Department of Inorganic and Physical Chemistry , Indian Institute of Science, Bangalore , Bangalore 560012 , India.
ACS Appl Mater Interfaces. 2019 Jul 31;11(30):27192-27199. doi: 10.1021/acsami.9b07657. Epub 2019 Jul 15.
Mesoporous carbon nitride (MCN) with well-ordered porous structures is a promising anode material for secondary ion batteries owing to their unique physico- and electrochemical properties. However, the practical application of these MCNs in sodium-ion batteries (SIBs) is still limited because of their confined interlayer distance, which results in restricted accommodation of Na ions inside the lattice. Here, we report on the synthesis of highly ordered sulfur-doped MCN (S-MCN) through a hard template approach by employing dithiooxamide (DTO) as a single molecular precursor containing carbon, nitrogen, and sulfur elements. The interlayer distance of carbon nitride is significantly expanded upon the introduction of larger S ions on the MCN lattice, which enables high capability of Na ion accommodation. We also demonstrate through the first-principles density functional theory calculation that the present S-MCN is highly optimized not only for the chemical structure but also for uptaking abundant Na ions with high adsorption energy. The specific discharge capacity of SIBs appears to be remarkably enhanced for S-MCN (304.2 mA h g) compared to the nonporous S-CN (167.9 mA h g) and g-CN (5.4 mA h g), highlighting the pivotal roles of the highly ordered mesoporous structure and S-doping in enhancing the electrochemical functionality of carbon nitride as an anode material for SIBs.
具有有序多孔结构的介孔碳氮化物（MCN）因其独特的物理和电化学性质，是一种很有前景的二次离子电池负极材料。然而，这些MCN在钠离子电池（SIBs）中的实际应用仍然有限，因为它们的层间距受限，导致晶格内钠离子的容纳受限。在此，我们报道了通过硬模板法，以二硫代草酰胺（DTO）作为含碳、氮和硫元素的单一分子前驱体，合成高度有序的硫掺杂MCN（S-MCN）。在MCN晶格上引入较大的S离子后，碳氮化物的层间距显著扩大，这使得钠离子具有高容纳能力。我们还通过第一性原理密度泛函理论计算表明，目前的S-MCN不仅在化学结构上得到了高度优化，而且对于以高吸附能吸收大量钠离子也进行了高度优化。与无孔S-CN（167.9 mA h g）和g-CN（5.4 mA h g）相比，S-MCN的SIBs比放电容量显著提高（304.2 mA h g），突出了高度有序的介孔结构和S掺杂在增强碳氮化物作为SIBs负极材料的电化学功能方面的关键作用。
