Slurry electrodes employ a suspension of solid electronically conductive particles capable of supporting electronic charge transport through particle contact at high loading. Despite their operational flexibility, this reliance on particle contact for electron transport has historically kneecapped their use at scale - their low conductivity becomes inherently limiting in high rate applications. The intuitive solution to increase loading of electronically conductive particles does indeed increase conductivity and performance, but the same particle interactions that lead to improved electronic transport are also responsible for increased viscosity of the suspension -- leading to higher parasitic pumping losses at scale. Contemporary design of slurry electrode has continually grappled with this: that there is an inevitable tradeoff between favorable electrochemical properties and favorable viscoelastic properties.
In reality, this tradeoff between electrochemical performance and viscoelastic performance has been confounded by the unintuitive relationship between electronic conductivity of the electrode and electrochemical performance; electrochemical systems do not behave according to ideal circuit laws and instead are governed by complex coupled relationships between capacitance, reaction kinetics, mass transport, and of course electron transport, as defined by porous electrode theory. Similarly, viscoelastic properties of the colloid remain an unintuitive function of particle dispersive and electrostatic forces defined by colloidal theory that may be orthogonal to electrochemical properties. In this work, we explore what electrode properties lead to this orthogonality, and how exploiting multiple particle types with varying properties can enable design of slurry electrodes bearing both markedly higher electrochemical performance and lower viscosity -- unburdened by the tradeoff previously caging the slurry electrode design space.