Enhanced cycling stability and rate capability of a graphene-supported commercialized Vat Blue 4 anode for advanced Li-ion batteries.

Commercialized Vat Blue 4 (VB4) has attracted more attention as a promising anode for large-scale applications in Li-ion batteries (LIBs) due to its high electrochemical activity, low price, and large-scale production. However, its moderate solubility results in severe capacity decay and low utilization of active components. Herein, we present a graphene-supported VB4 composite (VB4/rGO) prepared by a facile sonication and hydrothermal process for long cycling stability and high-rate capability. This design can significantly enhance the Li-storage properties, including high capacity (1045 mA h g at 0.1 A g), long cycling stability (537 mA h g even over 1000 cycles at 1 A g), and rate capability (315 mA h g at 5 A g). Strong π-π interaction derived from the aromatic rings within the π-conjugated system (graphene and VB4) and spatial confinement in-between graphene sheets both can suppress the high solubility of VB4 for superior capacity retention. Moreover, conductive graphene and channels in-between nanosheets can simultaneously facilitate the electron and Li transfer. This work demonstrates a simple and effective method to improve the electrochemical performance of commercialized Vat dyes and provides a low-cost and large-scale strategy to develop their practical application in the energy storage field.