Multifunctional copper sulfide nanoflowers for superior supercapacitors and microwave absorption

Abstract

With the rapid advancement of energy storage and electromagnetic shielding technologies, the development of multifunctional materials combining high-efficiency capacitive performance with superior absorption properties holds significant importance. Copper sulfide compounds, owing to their rich compositional diversity and tunable morphology, demonstrate potential application value in both electrochemical energy storage and electromagnetic wave absorption fields. This study employed a hydrothermal method to synthesize copper sulfide compounds with diverse morphologies. By adjusting the solvent composition (ethylene glycol and water), the material morphology was controlled for application in both two-electrode and three-electrode configurations. The composition and morphology of the copper sulfide compounds were characterized using XRD, SEM, TEM, XPS, FTIR and BET techniques. Cu_xS-40 demonstrated superior electrochemical performance in comparison with other compositions, thus demonstrating its efficacy in this regard. The specific capacitance of the material was found to be 796.6 F g⁻¹ at a given current density of 1 A g⁻¹. At a power density of 903.69 W kg⁻¹, when assembled into a device with activated carbon, Cu_xS-40 retained 100% of its initial value of specific capacitance at 10 A g⁻¹ after 5000 cycles. The experiment demonstrated that two such devices connected in series could effectively illuminate an LED bulb, thus further substantiating the considerable potential of Cu_xS-40 electrodes for applications in energy conservation. The Cu_xS-60 variant within the same series demonstrates exceptional microwave absorption performance, achieving a minimum reflection loss of −43.20 dB at a thickness of 3.0 mm and an effective absorption bandwidth of 5.52 GHz. This work highlights the dual application prospects of copper–sulfur compounds in both energy storage and electromagnetic shielding fields.