Dimensional effects on the electronic conductivity and rheological behaviors of LiFePO4 catholytes for rechargeable lithium slurry flow battery

Rechargeable lithium slurry flow battery represents a promising energy storage technology that combines high energy, affordable price, long life, easy maintenance and improved safety. Catholyte is a key component of lithium slurry flow battery, and its charge transport properties and rheological behaviors show a major influence on the electrochemical storage performances of lithium slurry battery. Herein, catholytes based on LiFePO4 cathode particles with different low-dimensional nanostructures (i.e., 0D nanoparticles, 1D nanorods and 2D nanosheets) were prepared to study the dimensional impacts on the electronic conductivity and rheological behaviors of the catholytes. Highest electronic conductivities of the three catholytes were measured at a LiFePO4 mass content of 20 wt.% regardless of particle dimension. The catholytes prepared by 2D nanosheets showed the maximum static viscosity and yield stress because of their smaller sizes. Furthermore, it also demonstrated much improved electrochemical storage performance in a lithium slurry flow battery, by reversibly outputting a discharge specific capacity of >150 mAh g−1 in an intermittent test and stably operating for over 70 h in a continuous flow model. This work sheds lights on reasonable design of catholytes towards practical realization of high-performance lithium slurry flow batteries.