Hierarchical and Self-Supported Vanadium Disulfide Microstructures@Graphite Paper: An Advanced Electrode for Efficient and Durable Asymmetric Capacitive Deionization
Xiaoru Wen, Meiqi Zhao, Zhibo Zhao, Xiangdong Ma, Meidan Ye
Abstract
Two-dimensional transition-metal disulfides (TMDs) have aroused boosting attention for the capacitive deionization (CDI) application because of their amazing chemical and physical superiorities. Nevertheless, besides the unsatisfying desalination capacity, the reported TMD-based CDI electrodes mostly relied on the highly time-consuming and polymer binder-assisted slurry-coating electrode processing. Thus, the exploring of high-performance active materials accompanied by the simplified electrode processing remains a great challenge. Herein, a novel hierarchical and self-supported VS2@graphite paper (GP) electrode consisting of numerous VS2 nanosheets vertically grown on the GP substrate was rationally proposed as an advanced CDI electrode. The superior microstructure framework (i.e., hierarchical pore arrangement, enriched open void spaces, and free binder) enabled the electrode with a high specific surface area, optimized ion diffusion pathway, excellent electric conductivity, and good wettability. Accordingly, the binder-free self-supported VS2@GP electrode demonstrated a remarkable specific capacitance of 241.75 F/g. More importantly, when coupling with the activated carbon for the asymmetrical CDI unit, the constructed VS2@GP electrode delivered an outstanding salt adsorption capacity of 31.19 mg/g, excellent adsorption rate, and great long-term durability, which were significantly improved compared to those of the traditional powder electrode.