MoS₂-graphene composite electrode for high energy hybrid Li-ion capacitors

A hybrid Li-ion capacitor represents an emerging class of devices, which results from the coupling of high energy density battery-type electrode materials at one side and high-power EDLC electrode at other side. Here, we develop a simple and scalable method including ball-milling, followed by heating process to synthesize MoS₂/graphene composite material. The structural and morphological analyses were carried out by powder X-ray diffraction (PXRD) analysis and scanning electron microscopy (SEM) technique. The composite electrode delivers high specific capacity (725 mAh g⁻¹ at 0.1 A g⁻¹ and 265 mAh g⁻¹ at 5 A g⁻¹). The hybrid device composed of MoS₂/graphene composite electrode as negative electrode and commercial activated carbon as the positive electrode exhibits a high energy density of 117 Wh kg⁻¹ at 200 W kg⁻¹ and a maximum power density of 3.9 kW kg⁻¹ at 79 Wh kg⁻¹. The hybrid device showed a long cycle stable Li storage capacity (62% after 5000 cycles at 1 A g⁻¹).