Fabrication of a highly stable Nb2O5@C/CNTs based anolyte for lithium slurry flow batteries

Abstract

Improving the stability of the anolyte and catholyte is crucial for the fabrication of high-performance lithium slurry flow batteries (LSFBs). To achieve an optimal slurry electrode for LSFBs, an anisotropic Nb₂O₅@C/CNTs nanocomposite was synthesized. The effects of active material content on the electrical and rheological behaviors of the slurry were studied systematically. An approximate bell-shaped curve depicts the variation trend of electronic conductivity under different Nb-based active material contents. The high aspect ratio of carbon nanotubes was found to be responsible for the formation of a conductive network in the slurry. The optimal matching point between active materials and KB increased from 8 wt% (Nb₂O₅@C) to 16 wt% (Nb₂O₅@C/CNTs). Under the condition that a KB percolation network was created, the as-prepared Nb₂O₅@C/CNTs anolyte delivers a high specific capacity of 217 mA h g⁻¹ and Coulombic efficiency > 92% in the flow reactor under a static mode. Moreover, the assembled flow reactor could work well under an intermittent flow mode, which indicates the feasibility of the as-prepared anolytes in a flow reactor. The fabrication of the highly stable Nb₂O₅@C/CNTs based anolyte will be helpful for the development of high energy density LSFBs with ultralong cyclability.