High performance asymmetric supercapacitor device based on lanthanum doped nickel‑tin oxide/reduced graphene oxide composite

Doping is the most promising approach to improve the electrochemical performance of metal oxide-based supercapacitor. Rare-earth element doping is helpful to improve the electrochemical performance of metal oxides due to the presence of unique 4f electronic configuration. Herein, Lanthanum (La) doped Nickel‑tin oxide/reduced graphene oxide (LNSRG) composite was successfully prepared via one-step hydrothermal method. The optimized LNSRG 2 composite exhibited ∼1238 F g⁻¹ specific capacitance at 3 A g⁻¹ current density using 6 M KOH as electrolyte. The effect of electrolyte's pH on the electrochemical performances was investigated using various electrolytes. The asymmetric supercapacitor (ASC) device fabricated with LNSRG 2 as positive electrode material and sonochemically reduced graphene oxide (SRGO) as negative electrode material exhibited energy density of ∼38 W h kg⁻¹ at a power density of ∼870 W kg⁻¹ in the potential window of ∼1.6 V using 1 M Na₂SO₄ as electrolyte. The ASC device retained ∼75 % of its initial capacitance after 10,000 continuous charge-discharge cycles at 15 A g⁻¹ current density. Two ASC devices connected in series was capable of powering a 1.8 V red LED light.