Single-layer MnO 2 nanosheets: From controllable synthesis to free-standing film for flexible supercapacitors

Abstract Supercapacitors, as one type of significant power source and energy storage unit, have attracted more and more attention. However, designing well-organized electrode structures to endow the flexible supercapacitors with excellent performances still remains a challenge. Here, the ultrathin MnO 2 nanosheets with a thickness of 0.9 nm were produced and used for ideal building blocks of 2D architectures. The free-standing film were prepared by vacuum-assisted filtration and the following mild thermal treatment, which were used directly as a binder-free electrode for flexible supercapacitors. Such unique lamellar structure were favorable for electron transfer from MnO 2 to rGO. As a consequence, a high specific capacitance of 98 F g −1 at 50 A g −1 is achieved. Remarkably, the capacitance retention after 6000 cycles is more than 95%.