Rationally Designed Nanomaterials for Highly Efficient and Robust Electrochemical Lithium Recovery

Lithium-ion batteries (LIBs), which have changed our everyday lives by enabling the use of mobile devices, are now impacting the fields of transportation and large-scale energy storage. LIBs in these applications are needed in a few orders of magnitude larger than in the mobile electronics, and the demand for lithium in the global market is increasing dramatically. For this reason, there have been significant efforts to develop methods for separation and extraction of lithium from various sources, including LIB wastes, in order to diversify and secure the supply of lithium resources. One example is electrochemical lithium recovery process developed around a decade ago. By using spinel- or olivine-structured LIB cathode materials, lithium ion could be extracted with a high selectivity. In addition, chloride-capturing electrode with fast kinetics led to successful constitution and operation of the electrochemical system. Meanwhile, there have been rooms for further understanding on the behaviors of the electrode materials under the recovery conditions, which is often challenging as there are species other than lithium being present in large amounts while the lithium concentration could be very low. Herein, our recent works on comprehensive analysis of electrode materials for lithium recovery will be introduced, and based on the obtained understandings, the rationally designed electrode materials with high efficiency and durability will be presented. Simple but intuitive strategies in designing lithium-selective oxide and chloride-capturing organic/inorganic composite led to substantial improvements in the utilization rate of the active components and long-term stability of the electrochemical system.