Ever-increasing pseudocapacitance in RGO-MnO-RGO sandwich nanostructures for ultrahigh-rate lithium storage
Lithium ion batteries have attained great success in commercialization owing to their high energy density. However, the relatively delaying discharge/ charge severely hinders their high power applications due to intrinsically diffusion- controlled lithium storage of the electrode. This study demonstrates an ever-increasing surface redox capacitive lithium storage originating from an unique microstructure evolution during cycling in a novel RGO-MnO-RGO sandwich nanostructure. Such surface pseudocapacitance is dynamically in equilibrium with diffusion-controlled lithium storage, thereby achieving an unprecedented rate capability (331.9 mAh g−1 at 40 A g−1, 379 mAh g−1 after 4000 cycles at 15 A g−1) with outstanding cycle stability. The dynamic combination of surface and diffusion lithium storage of electrodes might open up possibilities for designing high-power lithium ion batteries.