Advanced anode materials with stable and fast K-ion storage behavior are of great significance for potassium-ion batteries (PIBs) toward large-scale applications, while it still remains a big challenging due to their intrinsic poor conductivity and large volume variation during cycles. Herein, we develop an internal interfacial engineering by encapsulating core-shell NiS₂@C nanoparticles within MOF-derived hollow carbon shell for superior PIB anodes. As-prepared yolk-shell NiS₂@C@C composite integrates the structure superiority of abundant interior void space, outer protective carbon shell and internal conductive carbon layer. Comprehensive experimental and theoretical methods illuminate that internal NiS₂/C interface is conductive to boost charge transport kinetics, enhance pseudocapacitive behavior, and mitigate mechanical stress in outer carbon shell. As a result, it manifests an ultrahigh capacity of 481 mA h g⁻¹ at 0.2 A g⁻¹, and guarantees the rate capability of 306 mA h g⁻¹ at 20 A g⁻¹. Moreover, it presents excellent cycle stability (358 mA h g⁻¹ after 1600 cycles at 1 A g⁻¹), which is extremely competitive among the best reported conversion anodes for PIBs.

具有稳定和快速钾离子存储行为的先进负极材料对于钾离子电池（PIB）的大规模应用具有重要意义，但由于其固有的导电性差和循环过程中体积变化大，这仍然是一个巨大的挑战。在此，我们通过将核-壳 NiS ₂ @C 纳米粒子封装在 MOF 衍生的中空碳壳中来开发内部界面工程，以获得优异的 PIB 阳极。所制备的蛋黄壳NiS ₂ @C@C复合材料综合了丰富的内部空隙空间、外部保护碳壳和内部导电碳层的结构优势。综合实验和理论方法阐明了内部 NiS ₂/C 界面有助于提高电荷传输动力学、增强赝电容行为并减轻碳外壳中的机械应力。因此，它在0.2 A g ^{-1时表现出481 mA hg -1}的超高容量，并保证在20 A g ^{-1时具有306 mA hg -1}的倍率能力。此外，它还具有出色的循环稳定性（在 1 A g ^-1下循环 1600 次后为358 mA hg ^-1），这在已报道的最佳 PIB 转化阳极中极具竞争力。