Transition metal sulfides as electrode materials for lithium-ion batteries have attracted significant research attention due to their high theoretical capacity, excellent redox reversibility, and earth abundance. However, this material family still suffers from poor conductivity and experiences huge volume changes. Here, we demonstrate a facile and scalable electrospinning method to prepare Ni₃S₂ and Co₉S₈ nanoparticles embedded in sulfur doped carbon nanofiber networks as a free-standing anode material for lithium ion batteries. Similar to literature findings, the coupling of two different metal sulfides indeed synergistically promoted the electrochemical performance. Embedding them within individual carbon nanofibers not only enhances the intrinsic conductivity, but also provides a highly stable structure, which results in excellent battery performance. Furthermore, the individual carbon nanofibers intertwine with each other to form a free-standing 3D nanofiber network which acts as a freeway network for fast electron transfer and the pores between fibers allow easy penetration of the electrolyte, namely easy lithium ion access to active nanoparticles. When directly applied as the anode in lithium ion batteries, the free-standing nanofiber mat bypassed all slurry making steps and showed excellent cycling stability with a high specific capacity of 528 mA h g⁻¹ after 200 cycles at a current density of 300 mA g⁻¹. Good rate capability was also obtained. Additionally, the charge storage process analysis indicated that the pseudocapacitive behavior of the material is attributed to its good performance. This work introduces a facile strategy to simultaneously and in situ generate Co₉S₈ and Ni₃S₂ nanoparticles within a S-doped carbon fiber matrix via facile electrospinning followed by a one-step heating procedure. It is demonstrated that the free-standing transition bimetallic sulfide nanofibers prepared are very promising for light and small battery applications.

中文翻译：

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直接嵌入Ni3S2 / Co9S8 @ S掺杂的碳纳米纤维网络作为锂离子电池的独立式阳极

过渡金属硫化物作为锂离子电池的电极材料，具有较高的理论容量，优异的氧化还原可逆性和丰富的稀土元素，因此备受关注。但是，该材料系列仍然遭受导电性差的困扰，并且经历了巨大的体积变化。在这里，我们演示了一种方便且可扩展的静电纺丝方法来制备Ni ₃ S ₂和Co ₉ S ₈嵌入硫掺杂碳纳米纤维网络中的纳米颗粒，可作为锂离子电池的独立阳极材料。与文献发现相似，两种不同的金属硫化物的偶联确实协同促进了电化学性能。将它们嵌入单个碳纳米纤维中不仅可以增强固有导电性，而且还可以提供高度稳定的结构，从而获得出色的电池性能。此外，各个碳纳米纤维相互缠绕以形成独立的3D纳米纤维网络，该网络充当快速电子转移的高速公路网络，并且纤维之间的孔使电解质易于渗透，即锂离子易于进入活性纳米颗粒。当直接用作锂离子电池的阳极时，^-1在300毫安g的电流密度200次循环后^-1。还获得了良好的速率能力。此外，电荷存储过程分析表明，该材料的伪电容行为归因于其良好的性能。这项工作引入了一种简便的策略，即通过简便的电纺丝并随后一步加热程序，在S掺杂的碳纤维基质中同时原位生成Co ₉ S ₈和Ni ₃ S ₂纳米颗粒。结果表明，制备的自立过渡双金属硫化物纳米纤维对于轻型和小型电池应用非常有前途。