Na2Ti3O7 Nanotubes as Anode Materials for Sodium-ion Batteries and Self-powered Systems

Na2Ti3O7 (NTO) is a potential anode material with low discharge voltage for room-temperature sodium-ion batteries. In this work, NTO nanotubes were prepared by a hydrothermal method. XRD, SEM, TEM, and HRTEM studies are performed to investigate the composition, morphology, and structure. As anodes for sodium-ion batteries, NTO nanotubes show a reversible capacity of 126.2 mAh g(-1) at 100 mA g(-1). The discharge capacity can still reach 109 mAh g(-1) even for 2000 cycles. Solid-state sodium-ion batteries containing NTO-nanotube anodes and an Na3Zr2Si2PO12 solid electrolyte display a comparable performance to batteries with a liquid electrolyte. Moreover, the prepared solid-state sodium battery is also demonstrated to store mechanical energy harvested by triboelectric nanogenerators (TENGs). The discharge capacity reaches 121 mAh g(-1) at 5 mA g(-1).