Prussian blue analogue derived 3D hollow LiCoMnO4 nanocube for selective extraction of lithium by pseudo-capacitive deionization

Facing the huge demand of lithium resources in the green energy-oriented international development, the electrochemical lithium extraction technology is becoming one of the most popular way for lithium recovery from salt-lake brine or seawater. In this work, a novel LiCoMnO4 (LCMO) nanocube was facilely obtained by one-pot synthesis in the presence of Mn,Co-based bimetallic Prussian blue analogue (MnCo-PBA) and LiOH. The well-defined LCMO nanocube with unique hollow three-dimensional (3D) configuration was composed of small spinel structural LCMO nanocrystals with the particle size of 150 nm. In contrast with the LCMO block material, the specific surface area of LCMO nanocube increased, and the corresponding electrochemical activity enhanced significantly. As a Li+-selective cathode in capacitive deionization (CDI) device, LCMO nanocube exhibited high selectivity for Li+ extraction with excellent cycling stability. The Li+ adsorption amount achieved 700 μmol g−1, with the separation factor αMg2+Li+ of 88.7 (CMg2+/CLi+ = 30). The LCMO-based pseudo-CDI system was proved to be effective for Li+ extraction from the real salt-lake brine. This study delivered a new strategy for constructing a 3D porous Li+-intercalation material for Li recovery and beyond.