Layer-by-layer WS2-Cr heterojunction as a positive working electrode material for high-performance supercapattery applications

This study investigates the impact on the electrochemical performance of pristine sputtered WS2 through the strategic integration of a highly conductive chromium interfacial layer. This study involves the fabrication of two different samples via magnetron sputtering: type I, WS2-sputtered and type II, WS2/Cr (sputtering of Cr as an interfacial layer between sputtered-WS2 and NF). Afterward, structural, topographic and elemental composition of as-synthesized samples were inspected via XRD, SEM, Raman, and EDX. Following this, the energy storage performance were evaluated by employing CV, GCD, and EIS in three and two electrode assembly sequentially. In three electrode testing WS2 and WS2/Cr exhibited the specific capacity (Qs) of 661.79 C g- 1 and 1600 C g- 1 at 3 mV s-1 along with the capacity retention of 61.37 % (WS2) and 83.04 % (WS2/Cr), respectively. Similarly, through GCD WS2 shows the Qs of 637.34 C g- 1 at 0.8 A/g conversely, WS2/Cr exhibited the Qs of 1220 C g- 1 at 1.3 A g-1. Besides, the WS2/Cr demonstrated long-term longevity (capacity retention of 83.13 %) after 5000 GCD cycles. Based on exclusive electrochemical performance of type II of two samples, an asymmetric battery-type hybrid supercapacitor (WS2/Cr//AC) was fabricated by incorporating WS2/Cr and activated carbon (AC) as working and counter electrodes. WS2/Cr//AC revealed the Qs of 352 C g- 1 (785 F g-1) at 0.7 A/g. Besides, it deliberately delivered 81 Wh kg- 1 and 1750 W kg- 1 energy and power. The device exhibits excellent cyclic stability by maintaining its capacity after 5000 GCD cycles and illustrated 87.30 % capacity retention. Following that, semi-empirical approach was applied to quantify the capacitive and diffusive currents' contribution in overall device's performance. The results highlight that WS2/Cr hold colossal potential to fill the proficiency gap between presently keep-going devices and stern demands of future energy storage applications.