Flexible yolk-shelled NiCo₂S₄ hollow spheres/reduced graphene oxide (RGO) hybrid lamellar films were successfully fabricated by developing a facile strategy of vacuum filtration. After constructing the sandwich-like structures, the NiCo₂S₄ hollow spheres were inserted in-between the RGO nanosheets, which effectively prevented the self-restacking of RGO nanosheets and increased the interlayer spacing, leading to fast ion penetration and diffusion. The as-prepared NiCo₂S₄/2RGO hybrid lamellar films with excellent conductivity delivered an appreciable capacitance of 1000.5 F g⁻¹ at 1 A g⁻¹. Moreover, an asymmetric supercapacitor (ASC) was successfully synthesized utilizing activated carbon (AC) and NiCo₂S₄/2RGO hybrid lamellar films as the negative electrode and positive electrode, which manifested a high energy density (15.4 W h kg⁻¹) and power density (2227.3 W kg⁻¹) coupled with remarkable cycling stability (80.5% retention over 5000 cycles). After charging, two ASC devices connected in series were capable of lighting two red LEDs connected in parallel for at least 2.0 minutes.

中文翻译：

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灵活的蛋黄壳NiCo ₂ S ₄空心球/ RGO薄膜电极，用于高效的超级电容储能†

通过开发一种简便的真空过滤策略，成功地制备了柔性的蛋黄壳NiCo ₂ S ₄空心球/氧化石墨烯（RGO）杂化层状薄膜。在构造了三明治状结构之后，将NiCo ₂ S ₄空心球插入RGO纳米片之间，这有效地防止了RGO纳米片的自重堆积并增加了层间间距，从而导致离子快速渗透和扩散。制备的具有优异导电性的NiCo ₂ S ₄ / 2RGO混合层状薄膜在1 A g ^-1时可提供1000.5 F g ^-1的可观电容。此外，利用活性炭和NiCo ₂ S ₄ / 2RGO混合层状薄膜作为负电极和正电极成功地合成了不对称超级电容器（ASC），表现出高能量密度（15.4 W h kg ^-1）和功率密度（2227.3 W kg ^-1）和出色的循环稳定性（5000个循环中80.5％的保留率）。充电后，两个串联的ASC设备能够点亮两个并联的红色LED至少2.0分钟。