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A new solution method to synthesize NaTiO with titanium powder is presented, and the C/NaTiO nanocomposite with high specific surface area and tunnel structure as the electrode material has excellent electrochemical performance. The single electrode composed of the C/NaTiO nanocomposite based on carbon fiber fabric (CFF) has the highest area capacitance of 1066 mF cm at a current density of 2 mA cm, 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. The flexible symmetric solid-state SCs (C/NaTiO/CFF//C/NaTiO/CFF) based on different C/NaTiO mass were fabricated, and 7 mg SCs show the best supercapacitive characteristics with an area capacitance of 309 mF cm and a specific capacitance of 441 F g, it has a maximum energy density of 22 Wh kg and power density of 1286 W kg. 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/NaTiO nanocomposite has promising potential application in energy storage devices. [ABSTRACT FROM AUTHOR]

The K 2 Ti 6 O 13 nanobeams (K-TNBs) with tunnel structure have been prepared by simple hydrothermal method. To attain the flexible property and the high cycle stability, the carbon absorbed on K-TNBs (C@K-TNBs) supercapacitor (SC) has been encapsulated by the flexible PDMS (polydimethylsiloxane). The solid SC device shows excellent rate capability, high cycle stability and high flexibility at any degrees. The capacitance of the device can attain 301 F g −1 at current of 3 mA, energy density of 26.8 Wh kg −1 at power density 400 W kg −1 and power density of 1.47 kW kg −1 at energy density 16.3 Wh kg −1 . The retention of specific capacitance remains 82.7% after 10000 cycles at high current value of 21 mA. Three supercapacitors in series can light 100 green color commercial light emitting diodes (LEDs) for about 16 minutes. All these results indicate that the C@K-TNBs nanomaterial could provide the potential application in high performance supercapacitor. [ABSTRACT FROM AUTHOR]

Porous materials have superior electrochemical performance owing to its their structure, which could increase the specific and contact area with the electrode. The spinel Li4Mn5O12 has a three-dimensional tunnel structure for a better diffusion path, which has the advantage of lithium ion insertion and extraction in the framework. However, multi-space spherical materials with single morphologies are rarely studied. In this work, waxberry-like and raspberry-like nanospheres for Li4Mn5O12 have been fabricated by the wet chemistry and solid-state methods for the first time. The diameter of a single waxberry- and raspberry-like nanosphere is about 1 μm and 600 nm, respectively. The specific capacitance of Li4Mn5O12 was 535 mF cm−2 and 147.25 F g−1 at the scan rate of 2 mV s−1, and the energy density was 110.7 Wh kg−1, remaining at 70% after 5000th charge-discharge cycles. Compared with raspberry-like nanosphere Li4Mn5O12, the waxberry-like nanoporous spinel Li4Mn5O12 shows the better electrochemical performance and stability; furthermore, these electrochemical performances have been improved greatly compared to the previous studies. All these results indicate that the waxberry-like nanoporous spinel Li4Mn5O12 could provide a potential application in high performance supercapacitors. [ABSTRACT FROM AUTHOR]