New Spinel Cobalt Oxides, Potential Conductive Additives for the Positive Electrode of Ni−MH Batteries

Abstract

Temperature plays a key role in the formation of the cobalt-based conductive network at the positive electrode of alkaline batteries during the first charge. Electrodes pasted with CoO were oxidized in various concentrated alkaline media, in order to understand the phenomena involved. In these conditions, the experiments show the formation of a Co 3 O 4 type phase with defects. The presence of lithium in the electrolyte is proven to play an important role in the conductivity of the synthesized phases. Especially in 2.5 M LiOH, a pure phase is isolated that has a spinel structure close to Co 3 O 4 but containing H and Li. This phase is shown to be a good conductor and is also observed in (KOH, NaOH, LiOH) ternary industrial electrolyte. It could hence take part to the improvement of the properties of nickel electrodes observed when the beginning of the first charge is performed at high temperature.

Quantifying the Role of Nanotubes in Nano:Nano Composite Supercapacitor Electrodes

“…[23] However, we note that some hydroxides/oxides such as CoOOH are known to display enhanced conductivity in the presence of electrolytes. [24] As a result, the effective conductivity of our SC electrodes (in the presence of electrolyte) is probably somewhat higher than these dry values.…”

Bi2O3 modified cobalt hydroxide as an electrode for alkaline batteries

“…7b and c. In cobalt [26]. Several studies concerning relationship between the insertion/substitution of Co by other transition elements and the structural/conductivity properties of Co oxides have been previously reported [27]. Pralong et al show that, highly conducting phase of Co x 4+ Co 1−x 3+ OOH 1−x phase is formed in the presence of Bi [14].…”

The effect of cobalt on the electrochemical performances of Ni–Al layered double hydroxides used in Ni–M(H) battery

“…9). This may mean that Co 4 Al LDH in both the surface coating and mechanically mixing plays the role of the conductive agent during the electrode charging and discharging, just like metallic cobalt, Co(OH) 2 [42], CoO [43], spinel Co 3 O 4 [44], Na 0.6-CoO 2 [45] in the nickel hydroxide electrodes; however, in the Ni 3-CoAl LDH electrode, Co 3+ ions cannot act as electronic conductor like CoOOH between grains of active materials and the current collector, thus lower the usability of active materials. Fig.…”