Organic-Inorganic Superlattices of Vanadium Oxide@Polyaniline for High-Performance Magnesium-Ion Batteries

Abstract

Rechargeable magnesium batteries (RMBs) have attracted significant attention owing to the high energy density and economic viability. However, the lack of suitable cathode materials, owing to the high polarizability of divalent Mg-ion and slow Mg-ion diffusion, hinders the development of RMBs. V₂ O₅ is a promising RMBs cathode material, but its limited interlayer spacing is unfavorable for the rapid diffusion of Mg²⁺ , demonstrating unsatisfactory electrochemical performance. In this study, the superlattices of V₂ O₅ and polyaniline (PANI) with expanded interlayer spacing are assembled as the cathode material for RMBs. The intercalation of PANI in the interlayer region of V₂ O₅ significantly improves the reversible capacities, Mg²⁺ diffusion kinetics, and cycling performance of the PVO cathode. Furthermore, RMBs with PVO as the cathode and Mg metal as the anode deliver high specific capacities. The introduced polyaniline layer not only expands the interlayer spacing of V₂ O₅ , but also increases the electrical conductivity. Moreover, ex situ XRD characterization indicates that PVO does not undergo obvious phase transformation with the continuous insertion of Mg²⁺ , which may be ascribed to the π-conjugated chains of PANI that give flexibility to the structure to improve cycling stability. This study demonstrates that designing organic-inorganic superlattices is an efficient strategy for developing high-performance cathode materials for RMBs.

Keywords: 2D materials; batteries; magnesium; polymers; vanadium.