Tuning growth of MoS2 nanowires over NiTiCu nanostructured array for flexible supercapacitive electrodes with enhanced Li-ion storage
Bhanu Ranjan, Gagan Kumar Sharma, Davinder Kaur
Abstract
Rationally engineered three-dimensional (3D) clusters of MoS2 nanowires vertically anchored over a nanostructured NiTiCu shape memory alloy are fabricated using magnetron sputtering for flexible thin film supercapacitive electrodes. The heterostructure MoS2/NiTiCu deposited directly over flexible stainless steel (SS) offers remarkable electrochemical performance along with excellent mechanical stability, arising synergistically from the large specific surface of MoS2 nanowires and a high mechanical strength of NiTiCu@SS. The electrochemical studies in sulfate electrolytes (Li2SO4 and Na2SO4) manifest dominant charge transport efficiency of Li+ into the easily accessible electroactive sites of MoS2. The electrode delivers a superior gravimetric capacitance (379.25 F/g at 0.78 A/g) in addition to outstanding cycling stability (95.9% over 5000 cycles), suggesting high Li+ conductivity, low equivalent series resistance, and good substrate adhesion. Furthermore, the Power law and Dunn's approach reveal that charge storage into the highly porous MoS2 networks occurs mainly through the pseudocapacitive mechanism in Li2SO4 and capacitive processes in Na2SO4. Practically flexing the working electrode over 1000 bending cycles degrades the capacitance by only 17.17%, achieving highly desirable mechanical stability. Significantly, a superior power density of 12.54 kW/kg, while simultaneously achieving a high energy density of 52.67 Wh/kg, presents the electrode's immense potential for high-performance supercapacitor devices in flexible electronics.