11pt, fleqn, a4paper, ]LegrandOrangeBook The design of high-performance and cost-effective electrode materials for supercapacitors is attracting growing interest. Current research efforts focus predominantly on surface-level modifications such as foreign metal/anion doping to augment active sites and structural porosity, while intrinsic material engineering via compositional and crystallographic tailoring remains underexplored, despite its potential to fundamentally tune charge storage mechanisms. Here, based on the excellent properties of bimetallic bases (Mn and Co), we have synthesized a series of Co-doped Mn-based compounds with adjustable morphology and crystal phase by a simple hydrothermal method, in which the supercapacitor performance exhibits a trend of initial enhancement followed by degradation with the addition of Co 2+. Particularly, the sample of doping 60 mol% Co 2+ concentration exhibits exceptional charge storage characteristics, delivering the specific capacitance of 308 F·g -1 at 0.2 A·g -1, attributed to the optimal synergistic effects originating from the maximum ratio of Co 3+/Co 2+, which would offer an effective approach to enhance the electrochemical properties of transition metal oxides by systematically investigating the composition-structure-performance relationships.