Single Atoms Induced Electron Transfer and Spin Polarization for High‐Performance Asymmetric Supercapacitors

Features of low cost and high theoretical capacity render transition metal oxides (TMOs) as promising candidates for electrode material of supercapacitors. However, they intrinsically possess drawbacks of low conductivity, high charge transfer resistance, and slow diffusion kinetics. Herein, non‐precious metal single atoms (SAs) were introduced into TMOs to regulate the electronic structure for supercapacitors. For the obtained example CuSAs–Co 3 O 4 , the results of fine characterizations, quasi‐in‐situ techniques, DFT calculations, and magnetic property analyses reveal that the introduction of Cu SAs induces a dually enhanced optimization in electronic structure. On the one hand, electron transfer from Cu to the main reaction sites (Co sites) for increasing the quantity of electrons that can participate in electrochemical reactions. On the other hand, induced spin polarization can facilitate the occupation of Co 3+ (3d 6 ) varies from () to (), representing higher activity. Thus, fast electron conduction, enhanced capacitive reactions, and accelerated ion diffusion can be achieved. Eventually, the capacity of CuSAs–Co 3 O 4 can reach 960.0 C g −1 in 1 A g −1 , and the maximum energy density of the assembled asymmetric supercapacitor device is 72.7 Wh kg −1 at 0.83 kW kg −1 . This work provides significant method guidance and innovative insights on mechanism interpretation for designing the highly desired low‐cost and high‐performance electrode materials.