Boosting energy storage performance via electron pathway modulation in hierarchical NiCo oxide-sulphide hybrids

Abstract

This study systematically explored the enhancement of device energy storage capacity through nanostructure engineering aimed at modulating redox sites. For this, a hybrid electrode material was developed by compositing nickel-cobalt derivatives in both oxide and sulfide forms. The hierarchically structured NiCo-O/S electrode was fabricated via a two-step process: initial hydrothermal growth followed by electrodeposition. This design strategy integrates the structural integrity and abundant redox activity of NiCo2O4 with the high electrical conductivity and flexibility of NiCo2S4. Electrochemical evaluations revealed that an NCO-NCS electrode achieves a high specific capacity of 7310 mF/cm2, representing a 7-fold and 3-fold increase compared to NCO NCS alone, respectively. An asymmetric energy storage device was assembled in Swagelok configuration (NCO-NCS//AC), delivering a specific capacity of 374 mF/cm2 and an energy density of 0.117 mWh/cm2. The device retained 78% of its initial capacitance after 20,000 charge-discharge cycles, indicating significant cycling stability. Additionally, machine learning techniques were utilised to predict and forecast the cyclic stability of the device. The predictive performance parameters confirmed that an ML approach effectively captured device's cyclic dynamics. Collectively, these findings substantiate that hierarchical structural design, interfacial engineering, and lattice modulation represent effective strategies for advancing oxide-sulfide hybrid materials in energy storage applications. © 2026 Elsevier B.V.