Coupling Manipulation of Interfacial Chemistry and Coordination Structure in Vanadium Oxides Enables Rapid Magnesium Ion Diffusion Kinetics.

Abstract

Rechargeable magnesium batteries (RMBs) are a highly promising energy storage system due to their high volumetric capacity and intrinsic safety. However, the practical development of RMBs is hindered by the sluggish Mg2+ diffusion kinetics, including at the cathode-electrolyte interface (CEI) and within the cathode bulk. Herein, we propose an efficient strategy to manipulate the interfacial chemistry and coordination structure in oligolayered V2O5 (L-V2O5) for achieving rapid Mg2+ diffusion kinetics. In terms of the interfacial chemistry, the specific exposed crystal planes in L-V2O5 possess strong electron donating ability, which helps to promote the degradation dynamics of C-F/C-S bonds in the electrolyte, thereby establishing the inorganic-organic interlocking CEI layer for rapid Mg2+ diffusion. In terms of the coordination structure, the straightened V-O structure in L-V2O5 provides efficient ions diffusion path for accelerating Mg2+ diffusion in the cathode. As a result, the L-V2O5 delivers a high reversible capacity (355.3 mA h g-1 at 0.1 A g-1) and an excellent rate capability (161 mAh g-1 at 1 A g-1). Impressively, the interdigital micro-RMBs is firstly assembled, exhibiting excellent flexibility and practicability. This work gives deeper insights into the interface and interior ions diffusion for developing high-kinetics RMBs.