High-performance flexible supercapacitors based on C/Na2Ti5O11 nanocomposite electrode materials

Abstract

A new solution method to synthesize Na2Ti5O11 with titanium powder is presented, and the C/Na2Ti5O11 nanocomposite with high specific surface area and tunnel structure as the electrode material has excellent electrochemical performance. The single electrode composed of the C/Na2Ti5O11 nanocomposite based on carbon fiber fabric (CFF) has the highest area capacitance of 1066 mF cm−2 at a current density of 2 mA cm−2, which is superior to other titanates and Na-ion materials for supercapacitors (SCs). By scan-rate dependence cyclic voltammetry analysis, the capacity value shows both capacitive and faradaic intercalation processes, and the intercalation process contributed 81.7% of the total charge storage at the scan rate of 5 mV s−1. The flexible symmetric solid-state SCs (C/Na2Ti5O11/CFF//C/Na2Ti5O11/CFF) based on different C/Na2Ti5O11 mass were fabricated, and 7 mg SCs show the best supercapacitive characteristics with an area capacitance of 309 mF cm−2 and a specific capacitance of 441 F g−1, it has a maximum energy density of 22 Wh kg−1 and power density of 1286 W kg−1. As for practical application, three SCs in series can power 100 green light-emitting diodes (LEDs) to light up for 18 min, which is much longer than our previous work by Wang et al. lighting 100 LEDs for 8 min. Thus, the C/Na2Ti5O11 nanocomposite has promising potential application in energy storage devices.