Asymmetric Supercapacitor Constructed with Porous Carbon Generated from Rice Straw as the Negative Electrode and Ternary-Metal Oxides as the Positive Electrode

Abstract

In this work, we have developed efficient porous carbon materials (anode) from the agricultural waste of rice straw (RS) using potassium carbonate (K2CO3) and ferric nitrate (Fe(NO3)3 as an activating agent to enhance graphitization, which is denoted as KFeRS. Besides, the cathode materials of triple functional Co, Mn, and Ni oxides were prepared via the oxalate co-precipitation method. As a result, the fabricated asymmetric supercapacitor of CoMn2NiOx//KFeRS-0.12M achieves a maximum energy density of 80.08 Wh/kg and a power density of 720 W/kg at 0.2 Ag-1 and the energy density of 30.01 Wh/kg with a power density of 5400 W/kg at 1.0 Ag-1. This research also exhibits the potential of converting agricultural waste into high-efficiency energy storage materials by offering a low-cost and eco-friendly strategy for supercapacitor application. The green preparation method is expected to achieve large-scale industrial production, meet energy storage needs, and drive the global energy structure toward sustainability and environmental protection.

Keywords: Co-precipitation method, Rice straw, Sustainable energy, Aqueous electrolyte, Asymmetric supercapacitor