Flexible Aqueous Lithium-Ion Battery with High Safety and Large Volumetric Energy Density

Abstract

A flexible and wearable aqueous lithium-ion battery is introduced based on spinel Li1.1Mn2O4cathode and a carbon-coated NASICON-type LiTi2(PO4)3anode (NASICON=sodium-ion super ionic conductor). Energy densities of 63 Wh kg−1or 124 mWh cm−3and power densities of 3 275 W kg−1or 11.1 W cm−3can be obtained, which are seven times larger than the largest reported till now. The full cell can keep its capacity without significant loss under different bending states, which shows excellent flexibility. Furthermore, two such flexible cells in series with an operation voltage of 4 V can be compatible with current nonaqueous Li-ion batteries. Therefore, such a flexible cell can potentially be put into practical applications for wearable electronics. In addition, a self-chargeable unit is realized by integrating a single flexible aqueous Li-ion battery with a commercial flexible solar cell, which may facilitate the long-time outdoor operation of flexible and wearable electronic devices.