Enhancing sodium-ion storage performance of MoO2/N-doped carbon through interfacial Mo-N-C bond

Abstract

Na-ion batteries (SIBs) have attracted considerable attention as promising alternatives to commercial Li-ion batteries (LIBs) due to comparable redox potential, and natural abundance of Na. However, it remains challenging to explore suitable anodes for SIBs. Herein, a MoO2/N-doped carbon (MoO2/N-C) composite composed of MoO2 nanocrystals embedded within carbon matrix with a Mo-N-C chemical bond is prepared by a simple yet effective carbonization-induced topochemical transformation route. Na-ion half-cells using MoO2/N-C exhibit excellent cycling stability over 5000 cycles at 5 A g−1 and superior rate capability. Physicochemical characterizations and first principles density functional theory (DFT) simulations reveal that the formation of chemical bond at the interface between MoO2 and N-doped carbon plays an important role in the excellent charge storage properties of MoO2/N-C. More importantly, the interfacial coupling can efficiently promote interface charge transfer. Benefiting from this, Na-ion capacitors (SICs) constructed with the MoO2/N-C anode and activated carbon cathode can deliver an impressive energy density of 15 W h kg−1 at a power density of 1760 W kg−1, together with a capacitance retention of 92.4% over 1000 cycles at 10 A g−1. The proposed strategy in this paper based on interfacial chemical bond may hold pro mises for the design of high-performance electrodes for energy storage devices.