## 3 Results and Discussion  
### Characterization of the Prepared Nanopowder  
The thermal stability of the obtained powder was studied by means of a synchronous thermal analysis (Figure 1). As can be seen from the corresponding thermograms, the material undergoes 3 stages of mass loss in the investigated temperature range in the intervals 25-220, 220-410, and 410-860 \({}^{\circ}\)C. In the 1 st stage, the value of mass loss is about 6%, which is associated with the removal of residual solvent and sorbed atmospheric gases. The 2 nd stage shows a more intense mass reduction (\(\Delta\)m = 20.5%), accompanied by a more complex set of thermal effects. As can be seen from the DSC curve, in this case, there is a combination of endothermic effects in the region of 225-370 \({}^{\circ}\)C with a narrower exo-effect and a maximum at 265 \({}^{\circ}\)C. This behavior is characteristic of the carbonate hydroxide hydrate of cobalt of the composition Co(CO\({}_{3}\))\({}_{0.5}\)(OH)\(\cdot\)0.11H\({}_{2}\)O [55] and may be associated with the oxidation process Co\({}^{2+}\)\(\rightarrow\) Co\({}^{3+}\) as well as with crystallization of the corresponding oxide. The simultaneous presence of intense mass loss and thermal effects with energy absorption indicates active decomposition of the substance in a given temperature interval. This process continues even at further temperature increases, but its rate decreases significantly. The value of \(\Delta\)m at the third stage is about 5.5%, and at its final stage, an acceleration of the mass reduction process is observed, accompanied by an endothermic effect with a minimum around 838 \({}^{\circ}\)C associated with the decomposition of NiCo\({}_{2}\)O\({}_{4}\) oxide formed in the temperature range of 400-500 \({}^{\circ}\)C. The powder mass stabilizes with a further increase in temperature. Thus, the total mass loss in the investigated temperature range was about 32%. Taking into account the results of the analysis, the thermal stability of the powder under study is limited to a temperature of about 200 \({}^{\circ}\)C.  
The crystalline structure of the obtained powder was studied using X-ray powder diffraction analysis (XRD) (Figure 2). As can be seen from the overview diffractogram, the powder is characterized by a fairly low degree of crystallinity, which, as we noted earlier, is preferable for supercapacitor electrodes, contributing to a more effective penetration of charged particles deep into the material and interaction with a greater number of active centers on its surface. Nevertheless, the analysis results allow us to observe the simultaneous presence of a set of reflexes characteristic of nickel-cobalt carbonate hydroxide hydrate of composition M(CO\({}_{3}\))\({}_{0.5}\)(OH)\(\cdot\)0.11H\({}_{2}\)O (where M is Ni\({}^{2+}\) and Co\({}^{2+}\)) (JCPDS card no. 48-0083) [56; 57] and a signal at 2\(\theta\) = 12.2\({}^{\circ}\), probably related to (003) planes of the hydrolcite-like nickel-cobalt layered double hydroxides phase (JCPDS card no. 33-0429) [53; 58] on the XRD pattern. The main component in the composite thus formed is nickel-cobalt carbonate hydroxide hydrate, so in the first place, the following chemical interactions took place in the hydrothermal synthesis stage [56]:  
\[\mathrm{H_{2}O}+\mathrm{CO(NH_{2})_{2}}\rightarrow\mathrm{CO_{2}}+2\mathrm{NH_{ 3}} \tag{3}\]  
\[\mathrm{H_{2}O}+\mathrm{CO_{2}}\rightarrow\mathrm{2H^{+}}+\mathrm{CO_{3}}^{2-} \tag{4}\]  
\[0.11\mathrm{H_{2}O}+\mathrm{M^{2+}}+\mathrm{OH^{-}}+0.5\mathrm{CO_{3}}^{2-} \rightarrow\mathrm{M(CO_{3})_{0.5}(OH)}\cdot 0.11\mathrm{H_{2}O} \tag{5}\]  
The average crystallite size for the obtained M(CO\({}_{3}\))\({}_{0.5}\)(OH)\(\cdot\)0.11H\({}_{2}\)O, according to the analysis of XRD data, was 26 \(\pm\) 3 nm. Figure 1: Results of synchronous (TGA/DSC) thermal analysis of the obtained powder. FTIR spectroscopy was employed to study the set of functional groups in the synthesized sample composition (Figure 3).