Scalable production of engineered bi-functional MnCO3 materials derived from low-grade resources for supercapacitive and OER application

Abstract

Manganese-based electrode materials represent a burgeoning area of research, as manganese is earth-abundant, exhibits variable oxidation state and inexpensive. Additionally, it's conductivity, structural stability, purity, and facile bulk production from indigenous and affordable resources can pave a pathway for the development of sustainable multifunctional energy platforms. Herein, we propose the development of manganese carbonate (rMC) as bifunctional electroactive material from LGMOs using both inorganic and organic lixiviant. In the current process, manganese is selectively leached into the solution (>90 %) while passivating iron and other impurities. The processed leached liquor is further utilized to recover rMC via a single step facile chemical precipitation method. As obtained rMC is utilized as electroactive material for both supercapacitor and oxygen evolution reactions (OER) application. At 1 A g⁻¹, rMC showed high discharge specific capacitance of 194 F g⁻¹. It also showed a capacitance retention of 90.7 % for 5000 GCD cycles at 5 A g^-1. Further, a symmetric supercapacitor device was fabricated to establish the efficiency of rMC being used for practical applications. It showed discharge specific capacitance of 77 F g⁻¹ at 0.3 A g⁻¹. In terms of OER, rMC exhibits Tafel slope of 151 mV dec⁻¹ at 10 mA cm⁻². The present study shows the applicability of the low-grade resources to generate value added electrochemical bifunctional material for both supercapacitor and OER applications.