During the charging of a battery cell, electroconvection enhances the growth of non-planar deposits and reduces the life of the battery. We study two mechanisms by which electroconvection can be suppressed without significantly altering bulk electrolyte properties. First, we consider a rigid porous medium adjacent to the ion-selective surface and show that electroconvection can be effectively suppressed when the porous layer occupies most of the thin space charge layer, for a sufficiently small pore size. We also consider a scenario where polymers dissolved in the electrolyte are attracted to the metal electrode due to potential forces of attraction. The potential forces (such as van der Waals forces) acting on the dissolved polymers act as a restoring body force that opposes convective motions that disturb the polymer layer. The flow of particle--laden polymeric fluids has several industrial applications. We use numerical simulations to analyze the rheology of dilute suspensions of spheres and high aspect ratio spheroids (fibers). We study the transient rheology of a suspension of fibers when subjected to steady shear, as well as the rheology of a suspension of spheres in time varying imposed flows. We show that adding particles can reduce the transient extensional stress for large values of the extension rate.