High-rate nano-crystalline Li4Ti5O12 attached on carbon nano-fibers for hybrid supercapacitors

Abstract A lithium titanate (Li4Ti5O12)-based electrode which can operate at unusually high current density (300 C) was developed as negative electrode for hybrid capacitors. The high-rate Li4Ti5O12 electrode has a unique nano-structure consisting of unusually small nano-crystalline Li4Ti5O12 (ca. 5–20 nm) grafted onto carbon nano-fiber anchors (nc-Li4Ti5O12/CNF). This nano-structured nc-Li4Ti5O12/CNF composite are prepared by simple sol–gel method under ultra-centrifugal force (65,000 N) followed by instantaneous annealing at 900 °C for 3 min. A model hybrid capacitor cell consisting of a negative nc-Li4Ti5O12/CNF composite electrode and a positive activated carbon electrode showed high energy density of 40 Wh L−1 and high power density of 7.5 kW L−1 comparable to conventional EDLCs.