Enhanced redox activity in microwave-synthesized Ce–Co LDH electrodes for solid state supercapacitor devices

Abstract

A novel layered double hydroxide (LDH) electrode material composed of cerium hydroxide (Ce(OH)₃) and cobalt hydroxide (Co(OH)₂) was developed to address the low energy density problem of conventional supercapacitor electrodes. The LDH was synthesized via a microwave-assisted co-precipitation technique, offering a rapid and eco-friendly route. Structural, morphological, and surface analyses confirmed the formation of well-defined nanosheet-like interconnected structures with favorable characteristics. Notably, the material exhibited a high specific surface area of 155.8 m² g⁻¹, conducive to enhanced electrochemical performance. X-ray photoelectron spectroscopy depicted the coexistence of Ce³⁺/Ce⁴⁺ and Co²⁺/Co³⁺ oxidation states, signifying a high density of electroactive sites. Electrochemical characterization in a three-electrode setup revealed a remarkable specific capacity of 688 C g⁻¹ at 1 A g⁻¹, compared to the pristine Ce(OH)₃ (445 C g⁻¹). A symmetric supercapacitor was assembled using the composite electrodes, delivering an energy density of 35 Wh kg⁻¹ and a power density of 2250 W kg⁻¹ along with excellent cyclic stability. The composite also demonstrated superior rate capability and long-term cycling stability, retaining 96 % of its capacitance after 10,000 charge–discharge cycles. The device maintained robust performance at elevated current densities and successfully powered a commercial LED for over 100 s, underscoring its practical applicability.