UC Berkeley

Capacitive deionization (CDI) is an energy-efficient process for desalination of brackish (low-salinity) waters, and will be able to meet the freshwater demands of agriculture, industry, and potable water. One of the key challenges in widespread adoption of CDI is mechanical reliability of the electrodes manufactured by additive manufacturing processes. Mechanical reliability of electrodes depends on the optimal chemical composition of activated carbon-based electrode material. Traditional materials used for CDI electrodes are known to have adverse environmental effects from solvents such as N-Methyl-2-pyrrolidone (NMP) and Dimethyl sulfoxide (DMSO), and fluorine containing binders such as polyvinylidene difluoride (PVDF). In this paper we present (1) electrodes based on 'green chemistry' with reduced environmental impact, (2) stable chemical composition of electrodes with required mechanical reliability. We present the alternative CDI electrode composition using activated carbon, toluene as solvent, and polyvinyl butyral (PVB) as binder. We also mixed ion-exchange resins to produce composite electrode materials with toluene and PVB, which showed similar salt removal characteristics as composite electrodes with PVDF and NMP. Thus, the new electrode composition is a viable alternative for sustainable additive manufacturing of CDI electrodes with mechanical reliability and reduced environmental impact.