A Review of Battery Materials as CDI Electrodes for Desalination

Capacitive deionization: Capacitor and battery materials, applications and future prospects

Recent advances in capacitive deionization: A comprehensive review on electrode materials

Capacitive deionization (CDI) is a newly developed desalination technology with low energy consumption and environmental friendliness. The surface area restricts the desalination capacities of traditional carbon-based CDI electrodes while battery materials emerge as CDI electrodes with high performances due to the larger electrochemical capacities, but suffer limited production of materials. LiMn2O4 is a massively-produced lithium-ion battery material with a stable spinel structure and a high theoretical specific capacity of 148 mAh·g-1, revealing a promising candidate for CDI electrode. Herein, we employed spinel LiMn2O4 as the cathode and activated carbon as the anode in the CDI cell with an anion exchange membrane to limit the movement of cations, thus, the lithium ions released from LiMn2O4 would attract the chloride ions and trigger the desalination process of the other side of the membrane. An ultrahigh deionization capacity of 159.49 mg·g-1 was obtained at 1.0 V with an initial salinity of 20 mM. The desalination capacity of the CDI cell at 1.0 V with 10 mM initial NaCl concentration was 91.04 mg·g-1, higher than that of the system with only carbon electrodes with and without the ion exchange membrane (39.88 mg·g-1 and 7.84 mg·g-1, respectively). In addition, the desalination results and mechanisms were further verified with the simulation of COMSOL Multiphysics.

Capacitive deionization (CDI) is a novel water treatment technology based on the principle of double-electric-layer adsorption, which stores ions in the solution on the surface of electrodes by applying a low potential difference to achieve desalination. CDI has the advantages of low operating voltage (<1.2 V), small equipment footprint, low energy consumption, low cost and environmental friendliness. The performance of CDI is heavily dependent on the electrode materials. Carbon-based materials are widely used in CDI systems because of the large specific surface areas, lower price, and remarkable stability. To improve the CDI performance, extensive research efforts have been made for the modification of carbon-based materials. Defects in carbon-based materials play an important role in electrochemical processes and the introduction of defects is an important method to modify carbon-based materials. However, there is a lack of systematic summary of modification of carbon-based materials through introducing defects in CDI system. Therefore, this study makes the first attempt to review the modification of carbon-based materials of CDI based on defect engineering. The mechanism of enhancing CDI performance of carbon-based materials with the induction of different defects is analyzed and the future research prospects are proposed.

High Rate Li-Ion Batteries with Cation-Disordered Cathodes

Titanium disulfide decorated hollow carbon spheres towards capacitive deionization

Capacitive deionization (CDI) is a low energy desalination technology with long-cycle life, which utilizes high-porosity capacitive electrodes for capturing ions from flowing saline water [1, 2]. Though still suffering from relatively low desalination capacity, one major advantage of CDI technology is its low energy requirement and high rate operation for desalination. In recent years, much effort has been put on improving electrode materials for CDI applications. These studies have mostly focused either on the use of novel electrode materials or on surface modifications (e.g. metal oxide growth, chemical treatment, and thermal treatment) of the existing CDI electrode materials [1, 3, 4]. Although thermal treatment of carbon electrodes for improved charge storage is a well-established approach, the effects of various thermal treatment procedures on the performance of CDI electrodes still remain unexplored. Inherent similarities between the operating principles of supercapacitors and CDI technology might make one to think a similar correlation could be established between thermal treatment and the CDI performance. However, due to major differences in required charge storage mechanisms, a detailed study on various treatment conditions should be conducted to understand which conditions specifically promote better ion adsorption in CDI electrodes. Motivated by this, the effects of different thermal treatment conditions (i.e., temperature and gases) on salt adsorption performances of the activated carbon cloth (ACC) electrodes were investigated. Major discrepancy between stored charge versus salt adsorption capacity (SAC) was observed for different treatment conditions. To better assess these effects, additional BET and Raman tests on the ACC electrodes were also conducted. Results indicated interesting observations regarding charge storage capacity and SAC for different treatment conditions, which highlights the importance of selecting a suitable thermal treatment condition for enhancing the CDI performance of ACC electrodes.

Desalination of brackish water using capacitive deionization (CDI) technology

Activated carbon derived from the date palm leaflets as multifunctional electrodes in capacitive deionization system

The electrochemical performance and mechanism of cobalt (II) fluoride as anode material for lithium and sodium ion batteries

Electrochemomechanical degradation of high-capacity battery electrode materials

Origin of anomalous high-rate Na-ion electrochemistry in layered bismuth telluride anodes

Research progress on the application of carbon-based composites in capacitive deionization technology

Chloride pre-intercalated CoFe-layered double hydroxide as chloride ion capturing electrode for capacitive deionization

Capacitive deionization (CDI) technology is utilized for efficient treatment of industrial wastewater, characterized by low energy consumption and environmental protection. In order to comprehend the correlation between key experimental parameters and the electrosorption capacity (EC) of heavy metals in CDI technology, this paper employs a genetic algorithm (GA) to optimize a backpropagation artificial neural network (BPANN) for predicting the EC of CDI technology for heavy metal ions, with the characteristics of electrode materials converted into numerical characteristics for further analysis. Compared to the BPANN, the optimized GABPANN model demonstrates superior predictive accuracy. It achieves automatic adjustment of the hidden layer structure, neuron count, and transfer functions. Furthermore, the grey relational analysis indicates that the electrode material and the initial pH value of the solution are pivotal in determining the EC of heavy metal ions. This underscores the efficacy of machine learning (ML) algorithms in forecasting the nonlinear dynamics of CDI systems and elucidates the influence of individual parameters on the efficacy of heavy metal removal.