## 3 Results and Discussion
This movement of redox peaks is ascribed to the rate of intercalation of electrolytic ions on the surface of the active material and indicates the quasi-reversible features of redox reactions for both electrodes [24; 25]. In measuring CV from a low scan rate to a higher one (Figure 6a,b), no obvious change was recognized in the appearance, reflecting that both electrode materials are capable of providing excellent rate performance. Moreover, a linear path of the current with respect to scan rate implicates higher prosperity intercalation of OH\({}^{-}\) ions on the surface of active material. Optimized performance electrode material for energy storage was indorsed by comparing the CV of CCS-EG and CCS-glycerol at one fixed scan rate of 50 mV/s. As seen in Figure 6c CV, the profile of CuCo2S4 prepared with water and glycerol has an optimal area under the curve and archives a higher current, reflecting  
Figure 5: TEM analysis of CuCo2S4: (**a**) flakes-like CCS-EG; and (**b**) bricks-like CCS-glycerol. richer energy performance than the CCS-EG. This was further proved by estimating the specific capacitance and rate capability of the CCS-EG and CCS-glycerol by analyzing the charge-discharge mechanism at various current densities (5 mA/cm\({}^{2}\) to 15 mA/cm\({}^{2}\)). A comparative GCD profile at a current density of 5 mA/cm\({}^{2}\) for CCS-EG and CCS-glycerol is represented in Figure 6d. Obviously, CCS-glycerol reflects a richer discharge period (797 s) than CCS-EG (442 s), suggesting that it has a predominant charge storage capacity. Measuring GCD over a different current density enables the discovery of the rate capability of the active material. The GCD profiles at different current densities for CCS-EG and CCS-glycerol were represented in Figure 6e,f, respectively. The specific capacity (\(C_{s}\), F/g)/areal capacity (\(C_{A}\), nF/cm\({}^{2}\)) of each electrode was estimated at each current density using the discharge time (\(t_{d}\)), a mass of active material (m)/area of the electrode (1 cm\({}^{2}\)), and a voltage range (\(\Delta V\)) as [19] following:  
\[C_{s}=\frac{I\times t_{d}}{m\times\Delta V}, \tag{2}\]  
\[C_{A}=\frac{I\times t_{d}}{A\times\Delta V}. \tag{3}\]  
The CCS-EG electrode delivers the specific (areal) capacitance for 5, 7, 9, 11, 13, and 15 mA/cm\({}^{2}\) at 986.6 (3157), 931.2 (2980), 900 (2880), 869.2 (2781.4), 824.1 (2637.1), and 803.57 (2571.4) F/g (F/cm\({}^{2}\)), respectively. Compared to this, CCS-glycerol enables higher values of specific (areal) capacitance; the values for this electrode are 1459.7 (5692.8), 1400 (5460), 1345.05 (5245.7), 1277.3 (4981.4), 1185.7 (4624.3), and 1109.9 (4328.6), respectively. The CCS-EG electrode was found to be richer in rate capability than CCS-glycerol, which gives 81.4% of the initial capacity, even over the three-fold increase in the current density, i.e., from 5 mA/cm\({}^{2}\) to 15 mA/cm\({}^{2}\), while the later electrode retains 76.03%. This reflects that the diffusion rate of electrolytic ions on the surface of CCS-EG does not much vary with the current density, as in the case of CCS-glycerol. The GCD curves of both electrodes are almost symmetric in shape, suggesting a high level of coulombic efficiency. Moreover, distinct plateaus of GCD profiles give evidence of the large Faradaic redox reactions at the electrode-electrolyte interface, similar to that noted from CV curves [24]. Furthermore, in the case of both electrodes, the discharge time (t\({}_{\text{d}}\)) estimated at the respective current density advances the charging time (t\({}_{\text{c}}\)), indicating that both electrodes enable higher levels (above 100%) of coulombic efficiency. The predominant capacitive performance of CCS-glycerol reflects the rational design with spongy mud-like bricks and rectangular prisms, enabling larger interface coupling, abundant electroactive points, and a free path for ion insertion and desertion.