Co‐MnO<sub>2</sub> Nanorods for High‐Performance Sodium/Potassium‐Ion Batteries and Highly Conductive Gel‐Type Supercapacitors
Jun Han, Diansen Li, Lei Jiang, Daining Fang
Abstract
Abstract Manganese dioxide (MnO 2 ) is considered as a strong candidate in the field of new‐generation electronic equipment. Herein, Co‐MnO 2 has excellent electrochemical properties in tests as the cathode electrode of sodium‐ion batteries and potassium‐ion batteries. The rate performance remains at 50.2 mAh g −1 at 200 mA g −1 for sodium‐ion batteries. X‐ray diffraction (XRD) is utilized to evaluate the crystal structure transition from Co 0.2 ‐MnO 2 to NaMnO 2 with discharge to 1 V, proving that Co‐doping does indeed facilitate the acceleration of ion transport and support layer spacing to stabilize the structure of MnO 2 . Subsequently, highly conductive (0.0848 S cm −1 ) gel‐type supercapacitors are prepared by combining Co 0.2 ‐MnO 2 , potassium hydroxide (KOH), and poly(vinyl alcohol) (PVA) together. Co 0.2 ‐MnO 2 provides capacitive behavior and strengthens the hydrogen bonds between molecules. KOH acts as an ion crosslinker to enhance hydrogen bond and as electrolyte to transport ions. 5 wt% Co 0.2 ‐MnO 2 @KOH/PVA has superb mechanical endurance, appreciable electrical conductivity, and ideal capacitive behavior. The quasi‐solid‐state supercapacitor demonstrates stabilized longevity (86.5% at 0.2 mA cm −3 after 500 cycles), which can greatly promote the integration of flexible energy storage fabric devices.