22 / 2021-06-25 17:09:51

3D nanoflower-like MoSe2 encapsulated with hierarchically anisotropic carbon architecture: a new and free-standing anode with ultra-high areal capacitance for asymmetric supercapacitors

Wood, Carbon materials, MoSe2, MnO2, Supercapacitor

Wood is a green sustainable material with high abundance, and its free-standing carbon counterpart (carbonized wood) has been verified as a good substrate for applications of energy storage and catalysts. Herein, a novel anode material with a delicate composite structure, which is assembled by growing 3D MoSe₂ nanoflowers onto the hierarchically anisotropic carbon architecture derived from natural wood (3D MoSe₂ NFs@CDW), is designed and fabricated via a mild and simple combined method of ultrasound-assisted assembly and carbonization for the first time. Removing lignin composition (i.e., delignification process) enhances the porosity of wood and facilitates the permeation of chemical modifiers, resulting the self-assembly of MoSe₂ NFs along plentiful straight channels of wood and promote the migration of electrolyte ions. The structural superiority and synergistic effects from electrical double-layer capacitance and pseudocapacitance endow the free-standing anode with an ultra-high areal capacitance of 1043 mF cm^-2 at 1 mA cm^-2 and high cycling stability. Moreover, to verify the practical application of 3D MoSe₂ NFs@CDW anode in supercapacitor device, a common cathode (MnO₂@CDW) composed of CDW and MnO₂ is synthesized via a classic hydrothermal method, namely using CDW as a reducing agent to reduce potassium permanganate (KMnO₄) to MnO₂. As results, the asymmetric supercapacitor device consisting of this anode and a common MnO₂-based cathode yields a quite large energy density of 147 μW h cm^-2 at the power density of 2 mW cm^-2, which is higher than or comparable to that of some Li-ion batteries. These results suggest the huge application potential of this new anode for supercapacitors.