## 3 Results and Discussion
Due to this, the rate of the redox reactions is heavier than that of the CCS-EG electrode; hence, CCS-glycerol gives a higher capacitive performance. Moreover, the capacitive performance of both electrodes prepared in this case overrides the capacitance values of many of the Cu-Co-based bimetallic sulfide electrodes studied previously. The electrochemical performance of the CuCo\({}_{2}\)S\({}_{4}\)-based electrodes with different architectures is summarized in Table 1.  
An electrode surface that allows diffusion of K\({}^{+}\) ions from an electrolyte with a higher rate has a superior charge-storing capability. Therefore, to discover which electrode has the greater ability of K\({}^{+}\) diffusion, the diffusion coefficient of CCS-EG and CCS-glycerol have been evaluated using the CV profiles of both electrodes at different scan rates. The Randles-Sevcik equation was used to evaluate the diffusion coefficient values, which is as follows [26]:  
\[i_{p}=0.4463\times n\times F\times C\times A\times\sqrt{\frac{nFvD}{RT}}. \tag{4}\]  
Considering constant factors in the above equation (F--Faraday constant; R--molar gas constant; and T--temperature), this equation can be presented as follows:  
\[\frac{i_{p}}{v^{\
icefrac{{1}}{{2}}}}=2.69\times 10^{5}\times A\times C\times D^{ \
icefrac{{1}}{{2}}}\times n^{\
icefrac{{1}}{{2}}}. \tag{5}\]Figure 6: Electrochemical analysis: (**a**) CV at different scan rates for CCS-EG; (**b**) CV at different scan rates for CCS-glycerol; (**c**) comparative CV at 50 mVs\({}^{-1}\) of CCS-EG and CCS-glycerol; (**d**) comparative GCD at 5 mA cm\({}^{-2}\) of CCS-EG and CCS-glycerol; (**e**) GCD curves at different current density of CCS-EG; and (**f**) GCD curves at different current density of CCS-glycerol. Placing the values of \(i_{p}\)--the peak (reduction and oxidation) current value; A--area of the electrode (1 cm\({}^{2}\)); \(v\)--respective scan rate of the CV curve; C--concentration of electrolyte; and n--number of electrons; the diffusion coefficient can be estimated. The slope value noted through the linear fitting of the plot \(i_{p}\) vs. \(v^{1/2}\) will equalize the left side, i.e., \(\left(\frac{i_{p}}{v^{\prime 2}}\right)\) in the above equation. The plot of the \(i_{p}\) vs. \(v^{1/2}\) with linear fitting over peak points of reduction and oxidation for CCS-EG and CCS-glycerol is represented in Figure 7a. Considering slope values, the estimated value of the diffusion coefficient (reduction and oxidation) for CCS-glycerol is higher than that of the CCS-EG. CCS-EG has a diffusion coefficient of 2.81 \(\times\) 10\({}^{-4}\) cm\({}^{2}\)s\({}^{-1}\) for reduction and 2.46 \(\times\) 10\({}^{-4}\) cm\({}^{2}\)s\({}^{-1}\) for oxidation, respectively, whereas CCS-glycerol exhibits a diffusion coefficient of 2.96 \(\times\) 10\({}^{-4}\) cm\({}^{2}\)s\({}^{-1}\) (reduction) and 2.73 \(\times\) 10\({}^{-4}\) cm\({}^{2}\)s\({}^{-1}\) (oxidation), respectively. To analyze the governing of the charge-storage process (diffusion-controlled intercalation activity or surface-encouraged capacitive process) in the case of both electrodes, the power law relationship was utilized [27]:  
Figure 2:0  
Here, a is the constant, while \(b\) is the power law exponent, and \(i\) represents the value of peak current which follows the scan rate \(v\). The intercept and slope obtained through the linear fitting of plot log \(i\) vs. log \(v\) gives the values of a and b, respectively. The value of b recognizes that the charge storage is governed by diffusion-controlled intercalation activity or surface-encouraged capacitive process. Tending slope (b) toward 0.5 acknowledges that charge storage is from diffusion-controlled intercalation activity, and if it reaches 1.0, then the mechanism is governed by a surface-encouraged capacitive process [28]. The plot of log \(I\) vs. log \(v\) with linear fitting for both electrodes is represented in Figure 7b.