Sn catalyst for efficient reversible conversion between MoSe2 and Mo/Na2Se for high-performance energy storage

Abstract

Owing to incomplete reversible conversion reaction and sluggish ions diffusion kinetics for the anodes, transition metal selenides can hardly exert excellent capacity in sodium/potassium storage. Notably, the reversible conversion of M/Na2Se (K2Se) to MSe during charging process plays a key role in improving electrochemical performance. Herein, conventional MoSe2 was selected and vertically in situ grown on graphene (GN) substrate directly via Mo-C bonds to enhance the electrical conductivity of MoSe2 and facilitate the kinetics of electrochemical reaction during discharging process. In the following charging reaction, benefiting from the incorporating of catalyst of Sn, the discharging products of Mo/Na2Se (K2Se) could realize efficient conversion of Mo/Na2Se (K2Se) → MoSe2, contributing the reversible reaction of sodium/potassium storage. The diffraction spectrum and photoelectron spectrum verify the catalytic effect of Sn. The experimental evidence confirms that the MoSe2@GN with Sn catalyst anode delivers ultrastable reversible capacities of 444.8 mAh g−1 at 0.2 A g−1 for sodium ion batteries (SIBs), 248 mAh g−1 at 0.1 A g−1 for potassium ion batteries (PIBs) over 200 cycles and even tested at high current densities, the outstanding performance can be reached. Moreover, the anode exhibits promising practical potential inspired by the remarkable energy storage property in sodium and potassium ion full cells.