Embedding the functional nanostructures into a lightweight nanocarbon framework is very promising for developing high performance advanced electrodes for rechargeable batteries. Here, to realize workable capacity, core–shell (FeSe₂/C) nanostructures are embedded into carbon nanotube (CNT) framework via a facile wet‐chemistry approach accompanied by thermally induced selenization. The CNT framework offers 3D continuous routes for electronic/ionic transfer, while macropores provide adequate space for high mass loading of FeSe₂/C. However, the carbon shell not only creates a solid electronic link among CNTs and FeSe₂ but also improves the diffusivity of sodium ions into FeSe₂, as well as acts as a buffer cushion to accommodate the volume variations. These unique structural features of CNT/FeSe₂/C make it an excellent host for sodium storage with a capacity retention of 546 mAh g⁻¹ even after 100 cycles at 100 mA g⁻¹. Moreover, areal and volumetric capacities of 5.06 mAh cm⁻² and 158 mAh cm⁻³ are also achieved at high mass loading 16.9 mg cm⁻², respectively. The high performance of multi‐benefited engineered structure makes it a potential candidate for secondary ion batteries, while its easy synthesis makes it extendable to further complex structures with other morphologies (such as nanorods, nanowires, etc.) to meet the high energy demands.

中文翻译：

---

嵌入碳框架中的核壳FeSe2 / C纳米结构作为钠离子电池的独立阳极

将功能纳米结构嵌入轻量级纳米碳框架对于开发可充电电池的高性能先进电极非常有前途。在这里，为了实现可行的容量，通过一种简便的湿化学方法以及热诱导的硒化作用，将核-壳（FeSe ₂ / C）纳米结构嵌入到碳纳米管（CNT）框架中。CNT框架为电子/离子转移提供了3D连续路线，而大孔为FeSe ₂ / C的高质量负载提供了足够的空间。然而，碳壳不仅在CNT和FeSe ₂之间建立了牢固的电子连接，而且还改善了钠离子在FeSe _2中的扩散性。以及用作缓冲垫以适应体积变化。CNT / FESE的这些独特的结构特征₂ / C使之成为优良的主机存储与钠的546毫安g的容量维持^-1在100mA克即使经过100次循环^-1。此外，分布区和5.06毫安厘米体积容量^-2和158毫安厘米^-3也以高的质量负载16.9毫克厘米实现^-2分别。多受益工程结构的高性能使其成为二次离子电池的潜在候选者，而其易于合成的特性使其可以扩展到具有其他形态（例如纳米棒，纳米线等）的其他复杂结构，以满足高能量需求。