Heterointerface synergistic Na+ storage fundamental mechanism for CoSeO3 playing as anode for sodium ion batteries/capacitors

Abstract

The transition metal selenite CoSeO3 single crystal nanoparticles with primary particle size distribution ranging from 80 to 200 nm is systematically investigated as anode material for sodium ion batteries (SIBs)/capacitors (SICs). It achieves stable Na+ storage capacity of 280 mAh g−1 at a high current density of 10 A g−1 in CoSeO3||Na SIBs. Furthermore, the corresponding CoSeO3||Activated carbon (AC) SICs also presents a high energy density of 51 Wh kg−1 at a power density of 2 kW kg−1, along with 72% energy retention after 3000 cycles at 1 A g−1. Combining advanced microscopy (HRTEM, SEM), density functional theory (DFT) calculations and surface science (XPS), it is demonstrated that the CoSeO3 in-situ transform into binary oxides CoO/SeO2 and form heterointerfaces during the initial discharge/charge cycle. The coupled heterointerfaces between CoO and SeO2 could construct strong internal electric field, accelerating the electron/Na+ diffusion kinetics during the subsequent charge–discharge process and boosting Na+ pseudocapacitance storage. The finding of heterointerfaces synergistic sodium-ion storage fundamental mechanism of transition metal selenite might provide inspiration for the development of new anode material for sodium-based storage devices.