High areal capacitance of Fe₃O₄‐decorated carbon nanotubes for supercapacitor electrodes

Abstract

A conceptually new approach has been developed for the fabrication of magnetite (Fe 3 O 4 )-decorated carbon nanotubes (M-CNTs) for negative electrodes of electrochemical supercapacitors. M-CNTs were prepared by an ultrasonic-assisted chemical synthesis method, which involved dispersion of functionalized CNTs in water, Fe 3 O 4 formation on the CNTs surface, and particle extraction through liquid-liquid interface (PELLI). Palmitic acid was found to be an efficient new extractor for PELLI. The slurries produced after drying and redispersing M-CNTs and slurries obtained using PELLI were used for electrode fabrication. The electrodes prepared using PELLI showed superior performance due to reduced particle agglomeration. Testing results provided an insight into the influence of Fe 3 O 4 /CNTs mass ratio on the capacitance and capacitance retention at high charge-discharge rates. A capacitance of 5.82 F cm −2 (145.4 F g −1 ) was achieved in Na 2 SO 4 electrolyte using electrodes with high active mass of 40 mg cm −2 and ratio of active mass to current collector mass of 0.6. Good electrochemical performance was achieved at low impedance.The capacitance of the negative M-CNTs electrodes was comparable with capacitance of advanced positive MnO 2 -CNTs electrodes, which was beneficial for the fabrication of asymmetric devices. The asymmetric device has been fabricated, which showed promising performance in a voltage window of 1.6 V. K E Y W O R D Sasymmetric device, capacitance, carbon nanotube, composite, magnetite, supercapacitor

Coupling PEDOT on Mesoporous Vanadium Nitride Arrays for Advanced Flexible All‐Solid‐State Supercapacitors

“…where C s (F g −1 ), I (A), v (mV s −1 ), ΔV (V), and m (g) are the specific capacitance, response current, the scan rate, working potential window, and mass of the active material, respectively. Meanwhile, the GCD measurements were performed at current densities of 1-15 A g −1 , and the specific capacitance of all samples could be acquired by GCD curves according to the following equation [50] s…”

Reversible (De)Intercalation of Hydrated Zn2+ in Mg2+‐Stabilized V2O5 Nanobelts with High Areal Capacity

“…[1] Although lithium-ion batteries have achieved great success in the field of portable electronics, have been focused on most of the recent researches, while other important parameters such as volumetric and areal capacities (mAh cm −3 or mAh cm −2 ) are ignored. [10] In practical, high areal energy is crucial for applications like hybrid electric vehicles and electric vehicles that require high mass loading of electrode materials. However, recently reported zinc-ion battery cathode usually operates at rather low mass loading (0.5-2 mg cm −2 ), which is far from the standard of commercialization standard and leads to a low areal capacity below 1 mAh cm −2 .…”

Origins of Boosted Charge Storage on Heteroatom‐Doped Carbons

“…Raman spectra in Figure b also provide useful information on the degree of graphitization, where the D and G bands are related to the defects and crystallinity, respectively. The ratio of the D and G peaks intensity has the maximum value of 0.997 for NPOC‐900‐0.5 (0.98 for NPOC‐800‐0.5, and 0.96 for NPOC‐1000‐0.5), implying that the appropriate calcination temperature induces significant defects, which are favorable for the capacitive performances . The XPS spectra of the NPOC‐X‐0.5 (X=800, 900, or 1000) show the existence of C, N, O, P elements, confirming the successful synthesis of NPOC (Figure c; Supporting Information, Figure S4).…”