High-Performance and Ultraflexible Aqueous Rechargeable Lithium-Ion Batteries Developed by Constructing All Binder-free Electrode Materials

Aqueous rechargeable lithium-ion batteries (ARLIBs) as alternative energy storage devices have attracted tremendous attention because of their low cost and high safety. However, it is still a significant challenge to develop flexible high-performance ARLIBs for powering wearable devices because of the lack of all binder-free electrode materials. In this study, we develop one-step hydro-/solvothermal methods to design binder-free electrodes of LiCoO₂ polygonal-sheeted arrays and rugby ball-shaped NaTi₂(PO₄)₃ on carbon nanotube fibers as the cathode (LCO@CNTF) and the anode (NTP@CNTF). Both the electrodes are prepared at low temperatures without an extra calcination process, which is a great improvement for the growth process. The electrodes deliver remarkable capacity and extraordinary rate performance in a saturated Li₂SO₄ solution. Meanwhile, because of the synergy of LCO@CNTF and NTP@CNTF, an impressive capacity of 45.24 mA h cm^-3 and an admirable energy density of 67.86 mW h cm^-3 are achieved for the assembled quasi-solid-state fiber-shaped flexible ARLIB (FARLIB), which outperform most reported fiber-shaped aqueous rechargeable batteries. More encouragingly, our FARLIB possesses good flexibility, with a 94.74% capacity retention after bending 3000 times. Thus, this work represents a significant step toward developing FARLIBs and provides a new prospect in the design of wearable energy storage devices. © 2020 American Chemical Society.