High-performance sodium-ion hybrid capacitors based on an interlayer-expanded MoS₂/rGO composite: surpassing the performance of lithium-ion capacitors in a uniform system

Hybrid supercapacitors (HSCs) are novel, promising devices having features of both batteries and supercapacitors. Herein, we report HSCs (Li-HSC and Na-HSC in a uniform system) based on an interlayer-expanded MoS₂/rGO composite that show ultrahigh energy density and power density as well as superior cycle stability. The 3D network-structured interlayer-expanded MoS₂/rGO nanocomposite (3D-IEMoS₂@G) was synthesized and employed as the anode. Because the 3D architecture of the graphene skeleton frame delivered sufficient charges and the highly interlayer-expanded MoS₂ achieved fast ion diffusion, the as-prepared composite exhibited excellent performance as the anode material for both LIBs and SIBs (1600 mAh g^{− 1} at 100 mA g⁻¹ for the LIB; 580 mAh g⁻¹ at 100 mAh g⁻¹ and 320 mAh g⁻¹ at a high current density of 10 A g⁻¹). When paired with nitrogen-doped hierarchically porous 3D graphene (N-3DG), the obtained Na-HSC surpassed Li-HSC in a uniform system, showing an excellent performance of 140 Wh kg^{− 1} at 630 W kg^{− 1}, 43 Wh kg^{− 1} at an ultrahigh power density of 103 kW kg^{− 1} (charge finished within 1.5 s) and no distinct capacity attenuation after over 10000 cycles. Thus, a quantitative kinetic analysis was performed to understand the synergistic effect of the two electrodes and the resulting effect of ions in the hybrid supercapacitors and to further pave a general path for fabricating high-performance HSCs.