New-concept batteries based on aqueous li1/na1 mixed-ion electrolytes

Abstract

Rechargeable batteries made from low-cost and abundant materials operating in safe aqueous electrolytes are attractive for large-scale energy storage. Sodium-ion battery is considered as a potential alternative of current lithium-ion battery. As sodium-intercalation compounds suitable for aqueous batteries are limited, we adopt a novel concept of Li1/Na1 mixed-ion electrolytes to create two batteries (LiMn2O4/Na0.22MnO2 and Na0.44MnO2/TiP2O7), which relies on two electrochemical processes. One involves Li1 insertion/ extraction reaction, and the other mainly relates to Na1 extraction/insertion reaction. Two batteries exhibit specific energy of 17 Wh kg21 and 25 Wh kg21 based on the total weight of active electrode materials, respectively. As well, aqueous LiMn2O4/Na0.22MnO2 battery is capable of separating Li1 and Na1 due to its specific mechanism unlike the traditional ''rocking-chair'' lithium-ion batteries. Hence, the Li1/Na1 mixed-ion batteries offer promising applications in energy storage and Li1/Na1 separation.