Optimized Lithography-Free Fabrication of Sub-100 nm Nb₂O₅ Nanotube Films as Negative Supercapacitor Electrodes: Tuned Oxygen Vacancies and Cationic Intercalation

Abstract

The direct growth of sub-100 nm thin-film metal oxides has witnessed a sustained interest as a superlative approach for the fabrication of smart energy storage platforms. Herein, sub-100 nm Zr-doped orthorhombic Nb 2 O 5 nanotube films are synthesized directly on the Nb-Zr substrate and tested as negative supercapacitor electrode materials. To boost the pseudocapacitive performance of the fabricated films, supplement Nb 4+ active sites (defects) are subtly induced into the metal oxide lattice, resulting in 13% improvement in the diffusion current at 100 m V/s over that of the defect-free counterpart. The defective sub-100 nm film (H-NbZr) exhibits areal and volumetric capacitances of 6.8 mF/cm 2 and 758.3 F/cm 3 , respectively. The presence of oxygen-deficient states enhances the intrinsic conductivity of the thin film, resulting in a reduction in the band gap energy from 3.25 to 2.5 eV. The assembled supercapacitor device made of nitrogen-doped activated carbon (N-AC) and H-NbZr (N-AC//H-NbZr) is able to retain 93, 83, 78, and 66% of its first cycle capacitance after 1000, 2000, 3000, and 4500 successive charge/discharge cycles, respectively. An eminent energy record of approximately 0.77 μW h/cm 2 at a power of 0.9 mW/cm 2 is achieved at 1 mA/cm 2 with superb capability.

Optimized Fabrication of Bimetallic ZnCo Metal–Organic Framework at NiCo-Layered Double Hydroxides for Multiple Storage and Capability Synergy All-Solid-State Supercapacitors

“…Basically, at low current density, the ions have enough time to diffuse to the electrode surface. 69,81 Finally, this study opens the door for demonstrating ZnCo-MOF@NiCo-LDH film composite for application in all-solidstate devices. Designing more stable negative electrodes rather than activated carbon is expected to be full of promise especially when it comes to harsh conditions.…”

“…To this end, the EIS results illustrate the higher retention performance at low scan rate, and current density. Basically, at low current density, the ions have enough time to diffuse to the electrode surface. , …”

“…Finally, this study opens the door for demonstrating ZnCo-MOF@NiCo-LDH film composite for application in all-solid-state devices. Designing more stable negative electrodes rather than activated carbon is expected to be full of promise especially when it comes to harsh conditions. , This is basically because of the severe surface oxidation of carbon materials that occurs upon performing the stability at high current densities.…”

Binder-free Mn–V–Sn oxyhydroxide decorated with metallic Sn as an earth-abundant supercapattery electrode for intensified energy storage

“…Eqn ( 10)-( 15) describe the cooperative contribution from the faradaic redox reaction of Ni, V, and Sn and the pseudo-capacitive behaviour of Mn of the SMVS ternary metal oxyhydroxide composite. 35,39,85 For Mn 2+ /Mn 3+ : Mn(OH) 2 + OH À 4 MnOOH + H 2 O + e (10) For Mn 3+ /Mn 4+ : MnOOH + OH À 4 4 MnO 2 + H 2 O + e (11)…”

“…[7][8][9] Supercapacitors enjoy unique properties, over conventional capacitors and batteries, including their low fabrication cost, ease of fabrication, generation of less thermochemical heat, and simpler charge storage mechanisms, along with high power density and coulombic efficiency. [10][11][12][13][14] However, their limited energy densities pose the biggest obstacle to their widespread use in the energy storage sector. As a result, developing supercapacitors with high energy density while maintaining their power density and cycling stability has become a critical challenge.…”