Abstract Pyrite FeS2 is a promising alternative to typical intercalation cathodes for rechargeable lithium-ion batteries (LIBs) by virtue of its extremely high theoretical capacity. However, the inferior rate capability and fast capacity degradation caused by the sluggish reaction kinetics and large volume expansion upon lithiation greatly hinder its practical application. Herein, a chemical crosslinking strategy is developed for the synthesis of the yolk-shell pyrite FeS2@porosity-rich sulfur-doped carbon nanonetworks (FeS2@C NNs) as cathode materials for high-performance LIBs. The 3D nanonetwork structure constructed by tight covalent connection of carbon shells can act as highways to facilitate the electron transport kinetics, while the well-orchestrated internal cavities of the yolk-shell nanostructure provide large void space to accommodate the volume expansion of pyrite FeS2. In addition, the porosity-rich characteristic of carbon shells ensures fast pathways for the Li+ diffusion across the shells. As a result, the yolk-shell FeS2@C nanonetworks exhibit excellent high-rate capability (353 mAh g−1 at 10 C) and exceptionally long lifespan of 1000 cycles with a high capacity of 435 mAh g−1 at a large current density of 5 C, which is by far the best of pyrite FeS2-based cathodes for LIBs.

中文翻译：

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纳米网络结构的蛋黄壳FeS2@C作为锂离子电池的高性能正极材料

摘要 黄铁矿 FeS2 因其极高的理论容量而成为可充电锂离子电池（LIBs）典型插层阴极的有前途的替代品。然而，缓慢的反应动力学和锂化时的大体积膨胀导致的较差的倍率性能和快速的容量退化极大地阻碍了其实际应用。在此，开发了一种化学交联策略，用于合成蛋黄-壳黄铁矿 FeS2@富孔硫掺杂碳纳米网络（FeS2@C NNs）作为高性能 LIB 的正极材料。由碳壳紧密共价连接构建的 3D 纳米网络结构可以充当高速公路以促进电子传输动力学，而卵黄-壳纳米结构的精心设计的内腔提供了大的空隙空间来容纳黄铁矿 FeS2 的体积膨胀。此外，碳壳的多孔特性确保了 Li+ 跨壳扩散的快速途径。因此，蛋黄-壳 FeS2@C 纳米网络表现出优异的高倍率能力（10 C 时为 353 mAh g-1）和1000 次循环的超长寿命，在大电流密度下具有 435 mAh g-1 的高容量5 C，这是迄今为止最好的基于黄铁矿 FeS2 的锂离子电池正极。