Cobalt Nanorods as Transition Metal Electrode Materials for Asymmetric Supercapacitor Applications

Abstract

A porous cobalt nanorods (Co-NRs) structure is successfully synthesized via annealing of Co­(OH)2 nanorods at 350 °C with the presence of ethanol glycol (EG). The Co-NRs@Ni foam electrode displayed an ultrahigh specific capacitance of 3142.8 F g–1 at a current density of 1 mA cm–2; high-rate capability behavior can be proved by 87% of initial capacitance maintenance at 20 mA cm–2 and an excellent cycling life with a retention of 124.5% after 20,000 galvanostatic charge–discharge (GCD) cycles. The excellent electrochemical behavior of the Co-NRs@Ni foam electrode can be ascribed to the hierarchical porous nanorod structure, which can offer high electrical conductivity, enhance the electrolyte ions diffusion pathways, and abound electrochemical active sites. Its asymmetric supercapacitor device Co-NRs∥AC showed a specific energy density of 143.94 Wh kg–1, with a power density of 791.5 W kg–1 at a current density of 1 A g–1. Furthermore, an excellent cycling life behavior by retaining 95.88% of its initial capacitance throughout 20,000 GCD cycles was achieved. The exceptional electrochemical behavior of the Co-NRs@Ni foam electrode displays its great potential in applications as a promising electrode material candidate for energy conversion and storage equipment.

Highly Efficient Recovery and Recycling of Cobalt from Spent Lithium-Ion Batteries Using an N-Methylurea–Acetamide Nonionic Deep Eutectic Solvent

“…These showed a broad pattern indicating the amorphous nature of the extracted cobalt powder (Figure S2-B1). After annealing at 120 °C for 12 h, the peaks were well resolved (Figure S2-B2), denoting the presence of oxyhydroxides of cobalt, 33 as indicated from the peaks around 38.9, 50.6, 62, and 69.2 corresponding to the lattice faces of (012), ( 015), (107), and (113), respectively. Xray photoelectron spectroscopy of the precipitated cobalt powder indicates the presence of Co with the peaks at 781.2, 782.6, and 786.6 upon deconvoluting the band at 781 eV (Figure S2-C).…”

Fly ash electrodes fabricated by an acid-assisted subcritical water extraction method for supercapacitor applications

“…The well-known material for SCs mainly consists of transition metals (e.g., Ni, Co, and Mn) as reported elsewhere. [5][6][7] However, the extraction processes from their ores cause large quantities of waste and potentially damage our environment. 8 The alternative resource of SC materials is a must to develop especially with the spike in the price of such metals.…”