Vanadium Oxide with Molecular-Level Conducting Pathways for High-Rate Sodium-Ion Batteries

Vanadium oxides electrode materials for sodium-ion batteries have gained considerable attention due to their outstanding electrochemical properties, yet they still suffer from slow ion transfer, poor conductivity, and fragile structures. These can be improved by molecule intercalation, where the intercalated molecules pillar the adjacent layers and enlarge the interlayer spacing. Conducting polyaniline (PANI) is a promising intercalation material for vanadium oxide, benefiting from its high electrical conductivity and good electrochemical activity. Intercalating PANI could tune the interlayer structure and improve electrochemical performance, but is limited by poor cycling and rate performance. In this report, an approach of intercalating a short-chain aniline trimer (AT) into vanadium oxide (VO) is developed, enabled by a two-step simple mixing process. The selective insertion mechanism of sodium ions into V₂O₅ is systematically investigated. As a result, the ATVO electrode achieves an outstanding specific capacity of 408 mAh g at 0.1 A g^-1. A capacity retention of 78.7% after 800 cycles at a rate of 1 A g^-1 is reached. This study provides a pathway to intercalate short-chain conducting polymers into vanadium oxide to improve sodium-ion battery electrode materials performance, which paves the way for synthesizing simple, safe, and low-cost sodium-ion storage materials with promising electrochemical performance.