Manganese and Cobalt Heterostructures in Carbon Aerogels for the Improved Electrochemical Performance of Supercapacitors

The structural characteristics of electrodes are very important for supercapacitors (SCs) to improve their performance. Introducing transition metals in carbon aerogels (CAs) is an effective way to boost the application of supercapacitors. We develop a simple method to introduce two kinds of transition metals in a CA in one synthesis step, denoted MnCo/CA. There are small-sized Co nanocrystals and MnO₂ generated in situ, which not only produce abundant heterointerfaces but also enhance the specific surface area of the CA. Thanks to hierarchical porous structures and various MnO₂/Co/C heterostructure interfaces, the obtained MnCo/CA nanomaterials exhibit an excellent capacitance of 395.9 ± 5.0% F/g under 1.0 A/g, an outstanding rate capacity of 130.8 ± 3.0% F/g under 25.0 A/g, and a superior cycle life of 74.0% after 5000 cycles. Noticeably, benefiting from synergistic effects among metallic cobalt, manganese oxide, and CA, the MnCo/CA//MnCo/CA double-electrode supercapacitor presents a large voltage window (2.5 V) and then reaches a higher energy density of 63.1 ± 1.0% Wh/kg at 312.5 ± 5.0% W/kg. This research emphasizes the synergy effect between metal/metal and metal/carbon in CAs, which offers a simple way for advanced SC electrode materials.