Manganese and Cobalt\nHeterostructures in Carbon Aerogels\nfor the Improved Electrochemical Performance of Supercapacitors

The structural characteristics of electrodes are very\nimportant\nfor supercapacitors (SCs) to improve their performance. Introducing\ntransition metals in carbon aerogels (CAs) is an effective way to\nboost the application of supercapacitors. We develop a simple method\nto introduce two kinds of transition metals in a CA in one synthesis\nstep, denoted MnCo/CA. There are small-sized Co nanocrystals and MnO<sub>2</sub> generated in situ, which not only produce abundant heterointerfaces\nbut also enhance the specific surface area of the CA. Thanks to hierarchical\nporous structures and various MnO<sub>2</sub>/Co/C heterostructure\ninterfaces, the obtained MnCo/CA nanomaterials exhibit an excellent\ncapacitance of 395.9 ± 5.0% F/g under 1.0 A/g, an outstanding\nrate capacity of 130.8 ± 3.0% F/g under 25.0 A/g, and a superior\ncycle life of 74.0% after 5000 cycles. Noticeably, benefiting from\nsynergistic effects among metallic cobalt, manganese oxide, and CA,\nthe MnCo/CA//MnCo/CA double-electrode supercapacitor presents a large\nvoltage window (2.5 V) and then reaches a higher energy density of\n63.1 ± 1.0% Wh/kg at 312.5 ± 5.0% W/kg. This research emphasizes\nthe synergy effect between metal/metal and metal/carbon in CAs, which\noffers a simple way for advanced SC electrode materials.