LaMnO₃-CuO Composites for High-Performance Supercapacitors

The perovskite oxide LaMnO₃ and metal oxide CuO are gaining significant attention as a sustainable energy storage system. LaMnO_3±δ, with oxygen-ion intercalation capability, enables rapid energy storage and is an effective supercapacitor material. Meanwhile, Among the metal oxides, CuO is a promising candidate due to abundant resources, cost-effectiveness, eco-friendliness, and a simple synthesis process for various nanosized dimensions. Several research studies on CuO as a supercapacitor application have been conducted; however, compared to other metal oxides, the C_SP of CuO is low, although it has a high theoretical value (1783 Fg^-1). To address these limitations LaMnO₃-CuO composite samples, named as LMCO (1:0, 0:1, 9:1, 7:3, and 1:1) were prepared via autocombustion method followed by calcination at 1000 ^oC. The X-ray diffraction analysis confirms the presence of individual compounds in the desired ratio. The chemical composition of composites was determined by X-ray photoelectron spectroscopy (XPS). The presence of Mn²⁺, Mn³⁺, and Mn⁴⁺ and Cu²⁺ and Cu¹⁺ oxidation states revealed the presence of both LaMnO₃ and CuO in the composite. The electrochemical performance of the composite electrodes, fabricated on nickel foam and tested in 1M KOH solution, showed that the composites generally exhibited higher specific capacitance than the pure compounds, except for the LMCO (1:1) composites. LMCO(7:3) composites demonstrated a particularly high specific capacitance of approximately 646.8 F/g at a scan rate of 1 mV/s, which decreased with higher CuO content. This composite also achieved a specific capacitance of 517.1 F/g, with an energy density of 25.8 Wh/kg and a power density of 397.6 W/kg at a current density of 1 A/g in a 1M KOH electrolyte. The improved performance of the LaMnO₃-CuO composites could be attributed to reduced internal resistance, facilitated reversible faradic processes at the interface, and high Coulombic efficiency. These findings are significant for developing high-energy supercapacitor devices using this new composite as an electrode material.