Boosting the Electrochemical Performance of Mn-doped CuCo ₂ O ₄ /CuO Heterostructures for All-Solid-State Asymmetric Battery-type Supercapacitors

The introduction of Manganese (Mn) ions (2+ ⇋ 3+ ⇋ 4+) to transition metal oxides proved to be a potential strategy to tailor the redox behavior of these materials for energy storage. We fabricate a lower electronegative element (i.e., Mn) doped copper cobaltite and copper oxide (CuCo ₂ O ₄ /CuO; CCO) heterostructures electrodes through the hydrothermal synthesis route. The ensued electrodes have a more than 2-fold improvement in specific capacity (382.9 C g ⁻¹ ) than the undoped CCO electrode (120.8 C g ⁻¹ ) at 1 A g ⁻¹ . The all-solid-state asymmetric supercapacitor (ASC) practical device is constructed with higher Mn-doped CCO heterostructures as the positive electrode and activated carbon (AC) as the negative electrode. With a voltage window of 1.5 V, the fabricated ASC device has a high specific energy of 52.6 Wh kg ⁻¹ and specific power of 774.3 W kg ⁻¹ . The long-term cyclic stability of 92% capacity retention after 5000 cycles at the current density of 4 A g ⁻¹ . Additionally, two ASC devices are series-connected that can power up a red light-emitting diode (LED) display for more than 150 s, demonstrating the device’s efficient power delivery.