In situ growth of sulfur-incorporating NiCo-LDH for a high-performance hybrid all-solid-state supercapacitor

Abstract

High-performance energy storage systems are crucial in response to the growing demand for portable electronic devices. The present study focuses on the development and optimization of in situ growth of sulfur (S)-incorporating nickel–cobalt layered double hydroxides (NiCo-LDHs) on Ni-foam through a facile single-step solvothermal approach, adjusting the thiourea molar concentration to improve their electrochemical performance for high-performance supercapacitors. The electrochemical study shows that the optimal amount of sulfur precursor (9% thiourea) improves the charge transport properties of the product (9S-NC), leading to superior charge storage capacity. The 9S-NC nanosheets on the Ni-foam electrode show a high capacitance of 6530 F g⁻¹ at 2 A g⁻¹ (16.3 F cm⁻², 5 mA cm⁻²), which is three times higher than that of the in situ grown NiCo-LDH without sulfur incorporation. The fabricated hybrid supercapacitor (HSC) of 9S-NC//AC demonstrates a wide operating potential window of 1.8 V, delivering a high energy density of 97 W h kg⁻¹ in 2 M KOH aqueous electrolyte and 60 W h kg⁻¹ in solid-state PVA–KOH gel electrolyte, with a power density of 900 W kg⁻¹, surpassing previous reports. It maintains over 80% capacity retention after 10 000 cycles at 10 A g⁻¹, highlighting its excellent cycling stability. The practical application of the HSC device is demonstrated by powering an array of 96 LEDs, a motorized fan, and a calculator. These applications demonstrate that the S-incorporating NiCo-LDH hybrid supercapacitor is a reliable next-generation storage device, underscoring its capability to meet diverse energy demands in practical scenarios.