Promoting Volumetric Desalination Rate and Capacity via Highly Oriented, Densified Graphene Architectures

Abstract

Advancing electrode materials with high adsorption capacity and fast rate is crucial for seawater desalination in capacitive deionization (CDI). Here, we propose a highly oriented, densified graphene (HODG) electrode characterized by its ordered/short ion transport channels, abundant oxygen functional groups, high packing density (1.374 g cm^–3), and large specific surface area (543.72 m² g^–1), facilitating exceptional fast ion diffusion and ultrahigh volumetric desalination capacity. HODG delivers a volumetric capacitance of 308 F cm^–3 at 1 A g^–1, and a record-high volumetric salt adsorption capacity (v-SAC) of 57.70 mg cm^–3 with a rapid rate of 1.92 mg cm^–3 min^–1 at 1.2 V in 1000 mg L^–1 NaCl. Even after 50 cycles of adsorption–desorption, it can still retain 91.36% of its initial desalination capacity. This proposed design strategy offers a new avenue for the rational optimization of graphene architectures, boosting the development of high-performance CDI electrode materials toward practical applications.