“…Keeping in mind that CoOOH is much more soluble than Co 3 O 4 in acid media, this was nicely achieved by HCl treatments, as indicated by the absence of both the XRD peak shoulder (Figure c) and the diffuse infrared band (Figure c). The air-annealing of CoOOH at about 300 °C is well-known to give Co 3 O 4 , , but in our case we prefer the HCl treatment to preserve the low-temperature texture. 1 XRD patterns (Cr Kα, λ = 2.2897 Å) for the precipitates obtained at 25 °C (a), 100 °C (b), and after HCl leaching of the powder precipitated at 100 °C, labeled as Co 3 O 4 -AP (c).…”
Oxidative precipitation in an aqueous medium of highly self-compacted crystallized Co3O4 dense
nanoparticles (4−5 nm) leads to the formation of porous micrometric agglomerates exhibiting a well-defined porosity distribution. Postannealing of these powders induces drastic reorganizations first because
of the fast removal of trapped water and then because of the particles sintering, resulting in larger inter-particle voids. Electrochemical behavior of this nanometric material precipitated at moderate temperature
is found to be extremely dependent on the way the mixing with the SP conducting carbon is performed;
the better performances being obtained by a soft mixing in an organic solvent. This textural effect provides
a stable capacity over the first cycles (800 mA·h/g) and reveals a first cycle capacity loss of the same
extent as for bulk Co3O4, implying that the nanotexturation undergone by bulk oxide particles during
their first formatting cycle is not responsible for the corresponding initial loss. Through chemical analysis
of the electrolyte we found that the long-term capacity fading of our materials can be mainly attributed
to the dissolution of the active material within the organic electrolyte.
“…Keeping in mind that CoOOH is much more soluble than Co 3 O 4 in acid media, this was nicely achieved by HCl treatments, as indicated by the absence of both the XRD peak shoulder (Figure c) and the diffuse infrared band (Figure c). The air-annealing of CoOOH at about 300 °C is well-known to give Co 3 O 4 , , but in our case we prefer the HCl treatment to preserve the low-temperature texture. 1 XRD patterns (Cr Kα, λ = 2.2897 Å) for the precipitates obtained at 25 °C (a), 100 °C (b), and after HCl leaching of the powder precipitated at 100 °C, labeled as Co 3 O 4 -AP (c).…”
Oxidative precipitation in an aqueous medium of highly self-compacted crystallized Co3O4 dense
nanoparticles (4−5 nm) leads to the formation of porous micrometric agglomerates exhibiting a well-defined porosity distribution. Postannealing of these powders induces drastic reorganizations first because
of the fast removal of trapped water and then because of the particles sintering, resulting in larger inter-particle voids. Electrochemical behavior of this nanometric material precipitated at moderate temperature
is found to be extremely dependent on the way the mixing with the SP conducting carbon is performed;
the better performances being obtained by a soft mixing in an organic solvent. This textural effect provides
a stable capacity over the first cycles (800 mA·h/g) and reveals a first cycle capacity loss of the same
extent as for bulk Co3O4, implying that the nanotexturation undergone by bulk oxide particles during
their first formatting cycle is not responsible for the corresponding initial loss. Through chemical analysis
of the electrolyte we found that the long-term capacity fading of our materials can be mainly attributed
to the dissolution of the active material within the organic electrolyte.
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