Abstract
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.
Highlights
Energy storage has attracted unprecedented attention in recent years, and high-performance energy storage devices are under great demand[1]
The total pore volume was estimated from the single-point adsorption (P/P0 = 0.995), the specific surface area (SSA) was calculated by the BrunauerEmmett-Teller (BET) method, the micropore surface area and micropore volume were determined by the tplot method, and the pore size distribution (PSD) was derived from density functional theory (DFT)
The X-ray diffraction (XRD) pattern of the as-prepared 3D-IEMoS2@G is presented in Fig. 1a, which is obviously different from that of pristine 2H-MoS2 (JCPDS Card No 77-1716, Fig. S1 in ESM)
Summary
Energy storage has attracted unprecedented attention in recent years, and high-performance energy storage devices are under great demand[1]. There are two types of dominating electrical energy storage devices: secondary batteries and supercapacitors. Supercapacitors (electronic double layer capacitors (EDLCs)) store energy through a non-Faradic process (electrostatic charge adsorption), which leads to ultrahigh power density (~10 kW kg−1) and cycle stability (more than 10,000 cycles) and low energy density (5–10 Wh kg−1)[4]. Neither of these can currently meet the great demand for devices with both high energy density and high power density for electric vehicles and electronic devices
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