Regenerative electrochemical ion pumping cell based on semi-solid electrodes for sustainable Li recovery

Abstract

Demand of lithium is expected to increase drastically in coming years driven by the market penetration of electric vehicles powered by Li-ion batteries, which will require faster and more efficient Li extraction technologies than conventional ones (evaporation in brines). The Electrochemical Ion Pumping Cell (EIPC) technology based on the use of Faradaic materials is one of the most promising approaches. However, its relatively short lifespan prevents its commercial deployment. Herein, a new EIPC concept based on the use of semi-solid electrodes is proposed for the first time, which takes advantage of the rheological characteristics of semi-solid electrodes that enable simple and cheap regeneration of the Regenerative Electrochemical Ion Pumping Cell (REIPC) systems after reaching its end-of-life. A proof-of-concept for REIPC is accomplished by simple replacement of the semi-solid electrode demonstrating a remarkable electrochemical performance (e.g. 99.87%cycle−1, 99.98%h−1, 3–4 mAh cm−2) along with a competitive ion separation (e.g. 16.2 mgLi·gNiHCF−1, 4 gLi m−2 and 15.6 Wh·mol−1). The use of semi-solid electrode offers other unique features such as a significant cost reduction of 95% for every regeneration regarding conventional EIPC, proving that REIPC concept successfully addresses the issues associated to the sustainability and recyclability of the conventional EIPC's for lithium capturing.