Preparation–Morphology–Performance Relationships in Cobalt Aerogels as Supercapacitors

Abstract

The ability to direct the morphology of cobalt sol-gel materials by using the simple synthetic parameters in epoxide-driven polycondensations has been dramatically demonstrated, and the influence of such morphological differences upon the supercapacity of the materials has been explored. Precursor salt, epoxide, and solvent all influence the speed of the sol-gel transition and the size and shape of the features observed in the as-prepared materials, thereby leading to highly varied microstructures including spheres, sponge-like networks, and plate assemblies of varied size. These morphological features of the as-prepared cobalt aerogels were observed for the first time by high resolution scanning electron microscopy (HRSEM). The as-prepared aerogel materials were identified by powder X-ray diffraction and thermogravimetry as weakly crystalline or amorphous cobalt basic salts with the general formula Co(OH)(2-n)X(n) where X = Cl or NO3 according to the precursor salt used in the synthesis. For all samples, the morphology was preserved through mild calcining to afford spinel phase Co3O4 in a variety of microstructures. Wide-ranging specific surface areas were determined for the as-prepared and calcined phases by physisorption analysis in agreement with the morphologies observed by HRSEM. The Co3O4 aerogels were evaluated for their supercapacitive performance by cyclic voltammetry. The various specimens exhibit capacitances ranging from 110 to 550 F g(-1) depending upon the attributes of the particular aerogel material, and the best specimen was found to have good cycle stability. These results highlight the epoxide-driven sol-gel condensation as a versatile preparative route that provides wide scope in materials' properties and enables the analysis of structure-performance relationships in metal oxide materials.

Regulating Lithium Nucleation and Deposition via MOF‐Derived Co@C‐Modified Carbon Cloth for Stable Li Metal Anode

“…Second, the well‐defined array structure can increase the active surface area to enhance electrolyte absorption capacity during circulation and promote uniform distribution of Li ionic flux, thereby settling uncontrolled Li dendrite growth and following ameliorating lifespan. In addition, most electrode materials are typically prepared in powder form, which will inevitably reduce the active surface area and increase the “dead mass” of electrodes, as the post‐coating process is required for the electrode preparation with polymeric binder 24–26. In contrast, herein, a free‐standing and binder‐free host of Li metal anode can be obtained by directly growing well‐aligned nanoarrays on carbon cloth, completely eliminating the using of binder.…”

“…In addition, most electrode materials are typically prepared in powder form, which will inevitably reduce the active surface area and increase the "dead mass" of electrodes, as the post-coating process is required for the electrode preparation with polymeric binder. [24][25][26] In contrast, herein, a free-standing and binder-free host of Li metal anode can be obtained by directly growing wellaligned nanoarrays on carbon cloth, completely eliminating the using of binder. Figure 1a displays the schematic of synthetic strategy and architecture for the CC@CN-Co framework.…”

Synthesis of ZnO‐CuO Nanocomposite Aerogels by the Sol‐Gel Route

“…The epoxide addition sol-gel process has been demonstrated to be a relatively simple, inexpensive, and successful route to synthesize nontemplated monolithic metal oxide aerogels and xerogels [6][7][8][9][10][11][12][13][14] as well as nanocomposites [15][16][17][18][19]. Furthermore, variation of its processing parameters allows for control over the structure and properties of the resultant product [18,[20][21][22]. In this technique, metal oxide aerogels are synthesized using hydrated inorganic metal salts as metal precursors and epoxides as gelation initiators in aqueous or alcoholic media [5,10].…”

Recent Advance in Co3O4 and Co3O4-Containing Electrode Materials for High-Performance Supercapacitors

“…The results showed that the resistance of obtained Co3O4 polycrystalline decreased in spinel-type, whereas the capacity increased with an increase in Ni doping levels. Peterson et al [48] prepared Co3O4 with different morphologies via the sol-gel method and compared the performance of sphere-like, sponge-like, network-like, and plate-like…”