In Situ Construction of “Anchor‐Like” Structures in FeNCN for Long Cyclic Life in Sodium‐Ion Batteries

Abstract

Iron carbodiimide ( FeNCN) is a high-reactivity anode material for sodiumion batteries. However, strict synthesis technology and poor electrochemical stability limit its application. FeNCN polyhedrons are prepared using a facile one-step pyrolysis process. In these polyhedrons, many "anchor-like" structures are in situ constructed with FeC bonds. These FeC bonds connect the FeNCN polyhedrons closely. The FeNCN polyhedrons with "anchor-like" structures exhibit good electrochemical stability, that is, high capacity retention of 79.9% (408 mAh g −1 ) at 0.5 A g −1 after 300 cycles. Further analysis suggests that the FeC bond plays an important role to improve the structural stability of FeNCN polyhedrons. The "anchor-like" structures with FeC bonds can hold FeNCN polyhedrons closely when Na + intercalates, avoiding structural breakage with obvious capacity loss. This work provides a novel synthesis technology of FeNCN and helps related researcher to deepen the understanding of this material, as well as provide inspirations as to improving the electrochemical stability of related materials.

Realizing Fast Charge Diffusion in Oriented Iron Carbodiimide Structure for High-Rate Sodium-Ion Storage Performance

“…In recent years, several studies on carbodiimides materials used in battery systems have been successfully carried out, − ,− exhibiting great potential application in energy storage fields. Nevertheless, many of these studies include strict preparation conditions (Schlenk technique) ,, or multistep (both liquid and solid reactions) , synthesis techniques, bringing forward difficulties for further structural design of metal carbodiimide materials.…”

New Insight into the Mechanism of Simultaneous Determination of Ascorbic Acid, Dopamine, and Uric Acid with Graphene Encapsulated CoFe Alloys Electrochemical Sensor

“…[26] For CoFe@G, the binding energy at 283.9, 284.7, 285.5, 286.2, and 288.6 eV were attribut able to metal-carbon group (M-C), sp 2 C, sp 3 C, CO and CO in CoFe@G (Figure 3b). [34,[36][37][38][39][40] It is worth noting that the newly emerging M-C bond in CoFe@G will play a critical role in accelerating electron transfer during elec trochemical process. [41] Fe 2p spectrum in Figure 3c illus trates the characteristic peaks of Fe 0 at 708.9/720.5 eV (2p 3/2 /2p 1/2 ), remaining peaks located at 711.7/724.7 eV (Fe 2p 3/2 /2p 1/2 ) with satellite peaks at 715.6 and 729.5 eV implies the Fe 3+ which is attributed to surface oxidation.…”

Metal Cyanamides/Carbodiimides: Structure, Synthesis and Electrochemical Energy Storage Performance

“…(1) [21][22][23]45] 。部分金属阳离子不能直接取代 [36,[47][48][49] 。黄课题组 [48] 开发了一种在有机体系中 合成金属氰胺化合物的通用策略，以甲苯/乙醇溶 剂为反应介质，油胺、十六烷胺、十八烷胺等伯胺 作为表面活性剂，实现了金属氰胺化合物的尺寸 和形貌可控合成， 制备出 Ag2NCN 纳米棒、 ZnNCN 纳米棒和 PbNCN 纳米颗粒。 制备的 Ag2NCN 纳米 棒具有更好的结晶性和更高的比表面积，与在水 溶液中沉淀得到的 Ag2NCN 微米晶相比，其光催 化性能显著增强。之后，黄课题组 [36,47] 通过无水 乙醇溶解氰胺与金属卤化物，形成均相反应体系， 加入有机强碱苄胺， 调控反应过程， 制备了尺寸小 于 10 nm 且单分散的 CdNCN、 MnNCN 纳米颗粒。 Koziej 等 [49] [19,51] Fig. 3 Electrochemical performance and charge storage mechanism of FeNCN and CoNCN anode materials for lithium-ion batteries [19,51] Eguia-Barrio [18] 和 Sougrati 等 [19] 分别独立报道了金 属氰胺化合物在电化学储能领域的应用，主要研 究了 MNCN (M=Cu、Zn、Mn、Fe、Co 和 Ni)作为 锂钠离子电池电极材料的电化学性能，开启了一 类新型负极材料的研究热潮 [16,[50][51][52][53][54][55][56][57][58][59][60][61] [53] Fig. 4 Electrochemical performance and charge storage mechanism of Cr2(NCN)3 anode material for lithium-ion battery [53] (3)…”

“…FeNCN，也可以用于钠离子电池的负极材料 [18][19] 。 Sougrati 等首先报道的 FeNCN 负极，展现出 400 mAh/g 的高比容量，200 圈循环后仍保持 86%，比 容量和循环稳定性均远高于 FeO，同时还具有较 高的倍率性能。最近， Cao 课题组 [56] 通过高温热解 草酸铁铵和尿素的混合物制备了 FeNCN 独特的锚 状结构。由于界面 Fe-C 键的形成，在进行多次电 化学循环的转化反应时， Fe-C 键可以在 FeNCN 被 还原时抑制 Fe 纳米晶迁移，增强其循环稳定性。 300 圈循环后，容量保持率为 79.9%，相 对无界面 键合的对比样品， 稳定性显著提高， 且比容量提升 了近 20%。通过进一步控制热解条件，Cao 课题组 [60] 制备了在碳衬底表面牢固负载的 FeNCN 晶粒。 由于 FeNCN 的准层状六方结构，FeNCN 晶粒沿…”