CuO-integrated WS2 electrodes on stainless steel for efficient energy storage applications

Abstract This study presents a unique hierarchical architecture in which the synergistic effect between the high-capacity CuO framework and conductive WS 2 nanosheets is effectively utilized. In contrast to traditional electrode systems, the binder-free heterostructure directly grown on the stainless steel substrate offers faster ion-transport channels and improved mechanical stability during repeated redox reactions. XRD and Raman spectroscopy analyses verify the successful formation of the desired molecular phases. Electrochemical measurements performed in a 1 M LiCl electrolyte with a three-electrode system reveal enhanced charge-storage performance for the hybrid structure. Notably, the CuO@WS₂/SS electrode delivers a specific capacitance of 665 F g⁻ 1 at 10 mV s⁻ 1 , which is substantially higher than that of pristine WS 2 /SS (385 F g −1 ). Kinetic analysis based on the power-law relationship indicates that charge storage in the CuO@WS 2 /SS composite electrode arises from both diffusion-driven and surface-controlled mechanisms. The incorporation of CuO markedly increases the capacitive contribution, reaching 66% at 70 mV s −1 and 80% at 300 mV s −1 , compared with the pristine WS 2 /SS electrode. To evaluate practical applicability, a symmetric supercapacitor (SSC) device is assembled by using the CuO@WS 2 /SS electrodes with a 1 M LiCl aqueous electrolyte. The device exhibits an impressive operating potential window of 1.5 V and demonstrates exceptional long-term stability with 94.6% capacitance retention after 10,000 continuous charge–discharge cycles. Furthermore, the SSC device delivers a maximum energy density of 30.8 Wh kg −1 at a power density of 1155 W kg −1 (at a specific current of 1 A g −1 ). Even at a high power density of 4696 W kg −1 (at 5 A g −1 ), it maintains a significant energy density of 9.3 Wh kg −1 . These results highlight the potential of transition metal chalcogenide/oxide heterostructures for high-performance and durable energy storage solutions.