Unraveling the Anion Storage Properties of Manganese-Doped SrTiO 3

Strontium titanate (STO), a cubic perovskite material, has gained recent attention as a supercapacitor active material with its pseudocapacitive energy storage attributed to anion intercalation. However, very few in-depth studies have been conducted to understand the anion storage properties of STO and its metal-doped derivative compounds. In this study, we explored the anion-insertion storage mechanism of Mn-doped strontium titanate (Mn-STO) compared to pristine STO. The polycrystalline Mn-STO, synthesized via solid-state reaction, showed 3-fold times higher electrochemical surface area and exhibited enhanced anion storage compared to pristine STO. Detailed anion kinetics and diffusion studies reveal that the anion storage in Mn-STO is dominated by the bulk diffusion-controlled pseudocapacitive process than in STO. Further, the supercapacitor fabricated with Mn-STO in a 3 M KOH aqueous electrolyte with 0.1 M MnSO additives demonstrated excellent cycling stability, retaining 100% capacitance after 10,000 cycles, highlighting the potential of Mn-STO as an electrode material for supercapacitor applications.