Effects of conductive additives on the percolation networks and rheological properties of LiMn0.7Fe0.3PO4 suspensions for lithium slurry battery

Abstract In depth understanding the evaluation behaviors of conductive percolation networks and rheological properties is important for developing high performance suspension electrodes. Herein, three kinds of conductive additives, Ketjen Black, multi-walled carbon nanotubes and graphene nanoplatelets, are utilized to systematically investigate the impacts of dimension and content on the rheological and electrochemical properties of LiMn0.7Fe0.3PO4 suspensions. The percolation threshold ranges are found to be 0.5-0.6 wt.%, 0.2-0.3 wt.% and 2.3-2.4 wt.% for KB, MWCNT and GNP-based suspensions, respectively. The inflection points for electronic conductivities of different conductive additives based suspensions are situated at 1.0 wt.%, 0.5 wt.% and 2.5 wt.%, respectively, and the static viscosities and yield stresses of KB and MWNCT-based suspensions possess the same inflection points as that of electronic conductivities. Nevertheless, GNP-based suspensions deliver a distinguishing tendency due to their relatively poor dispersion. Electrochemical characterizations indicate that 1.5 wt.% KB-based suspension delivers superior cycle and rate performances. Especially, the successful application of LMFP suspension to lithium slurry battery was demonstrated by a relatively stable cycle over 230 h. Our findings will be helpful for the development of lithium slurry batteries with robust conductive networks and high energy density.