Interfacial Bonding Behavior and Lithium Extraction Performance of Electrochemically Switched Ion Exchange Composite Film

Abstract

Purposes Electrochemically switched ion exchange (ESIX) is a novel technology for selective ion separation and recovery, which can be utilized for lithium extraction from salt lakes. In particular, the interfacial bonding behavior between the current collector and the electroactive composite film has an important influence on the electrochemical performance of the composite film. Methods Titanium and carbon-based composite film electrodes were prepared by using titanium plate and graphite plate as current collectors, respectively, with LiMn2O4 as electroactive Li-ion exchange material. The interfacial bonding behavior between the current collector and the composite film was discussed by adhesion test, and the electrochemical performance of different composite film electrodes were analyzed by cyclic voltammetry, AC impedance, and galvanostatic charge-discharge tests. Findings The results show that the adhesion strength between graphite plate and composite film (1.33 N/cm) is about twice that between titanium plate and composite film (0.71 N/cm), and the carbon-based composite film electrode exhibits better electrochemical performance. In addition, the carbon-based composite film electrode has better lithium extraction performance during 10 consecutive ESIX processes. The above results are attributed to the more sufficient adhesion between the graphite plate and the composite film, which leads to better interfacial conductivity, thereby enhancing the electroactivity and cycle stability of the composite film electrode. However, the oxide film formed on the surface of the titanium plate after multiple redox will produce a large interface resistance, thus weakening the conductivity of the titanium plate.

Keywords

• current collector
• titanium plate
• graphite plate
• limn2o4
• electrochemically switched ion exchange