Suspensions based on LiFePO4/carbon nanotubes composites with three-dimensional conductive network for lithium-ion semi-solid flow batteries

Lithium-ion semi-solid flow battery (Li-ion SSFB) is extraordinarily promising for the future energy storage owing to the high energy density and the flexibility from its inherent architecture. However, dominated by the percolating conductor network, the high viscosity of the suspensions for Li-ion SSFBs results in large pump dissipations and hinders a high content of the conductive additives in the suspensions, which restricts the further improvement with respect to the electrochemical performance for Li-ion SSFBs. To address this issue, the present study proposes to synthesize active materials together with carbon nanotubes (CNTs) for regulating the inter-action among the dispersed particles in the suspensions to reduce the influence of the percolating network on suspensions' viscosities. Specifically, the LiFePO4 (LFP) is synthesized with 5, 10, and 15 wt% CNTs to generate composites for preparing suspensions for Li-ion SSFBs. The results show that the suspensions based on the LFP/ CNTs composites effectively relieve the contradiction between the flowability and electrochemical performance, owing to the increased zeta potential and the formation of the 3D conductive network for the prepared micro -nano structured composites, where the suspension based on the LFP/CNTs composite with the 15 wt% CNTs to the LFP exhibits the relatively high flowability, fast charge transport, and excellent electrochemical performance.