Jianlin Li

Preparation and thermoelectric properties of multi-walled carbon nanotube/polyaniline hybrid nanocomposites

In this work, a facile strategy for the fabrication of PANI/multi-walled carbon nanotube (MWCNT) nanocomposites without the assistance of a dispersant is introduced. MWCNTs and polyaniline were homogeneously mixed by cryogenic grinding (CG) and then consolidated via Spark Plasma Sintering (SPS). X-ray power diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and field-emission scanning electron microscopy (FESEM) were employed to characterize the as-prepared composites. The XRD results showed that cryogenic grinding can refine the grain size of PANI and induce more dislocations. The FTIR spectra data showed that the peaks of the PANI/MWNT composites displayed a red shift. In the high resolution FESEM image, the layer-by-layer structure and smooth surface can be observed. The thermoelectric properties of the as-prepared nanocomposites were investigated as a function of MWCNT content. The results showed that the electrical conductivity increased remarkably with the increasing MWCNT content, and the maximum power factor was 10.73 × 10−8 W mK−2, higher than pure PANI. Additionally, as the MWNT content increased from 10% to 30%, the electrical conductivity of the PANI/MWNT composite increased from 3.51 S m−1 to 1.59 × 102 S m−1. This work demonstrates a simple and effective method for improving the dispersity of carbon nanotubes and the thermoelectric properties of conducting polymers.

Fabrication of layered Ti3C2 with an accordion-like structure as a potential cathode material for high performance lithium–sulfur batteries

In order to enhance the long-term stability of sulfur cathodes used in rechargeable high energy lithium–sulfur (Li–S) batteries, layered Ti3C2 (L-Ti3C2) with an accordion-like structure was prepared by exfoliating Ti3AlC2 in 40% hydrofluoric acid. The L-Ti3C2 was then loaded with sulfur (57.6 wt%) to form a S/L-Ti3C2 composite. The composite was then used as a cathode material for Li–S batteries, which showed a high initial discharge capacity of 1291 mA h g−1 and an excellent capacity retention of 970 mA h g−1 after 100 cycles. The results suggest that two-dimensional carbides, similar to graphene and/or graphite, are a promising material for a wide range of applications in Li–S batteries and other electrochemical energy storage devices.

An efficient thermoelectric material: preparation of reduced graphene oxide/polyaniline hybrid composites by cryogenic grinding

An alternative and facile strategy to fabricate conducting reduced graphene oxide/polyaniline (rGO/PANI) hybrid composites with highly enhanced thermoelectric properties is introduced. rGO and PANI were homogeneously mixed by cryogenic grinding and then consolidated via spark plasma sintering. X-ray diffraction, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy and transmission electron microscopy were employed to evaluate the phase structure and microstructure of the as-prepared composites. The results show that the CG technique could not only effectively refine the grain size of PANI, but also could induce more dislocations. The refined PANI particles are homogeneously dispersed and orderly arranged on the rGO templates as a result of the strong π–π conjugated interactions between PANI and rGO. The thermoelectric properties of the PANI samples containing different rGO content were systematically investigated. Compared with pure bulk PANI, rGO/PANI hybrid composites exhibit a distinct enhancement in the thermoelectric performance. Both the Seebeck coefficient and the electric conductivity were found to increase remarkably, resulting from the increased carrier mobility. The maximum Seebeck coefficient and electric conductivity of the rGO/PANI hybrid composites amazingly reached 15.934 μV K−1 and 1858.775 S m−1, respectively, and the maximum ZT was up to 4.23 × 10−4.

Synthesis and characterization of LiNi0.48Co0.18Mn0.3Mg0.02Ti0.02O2 as a cathode material for lithium ion batteries

The layered oxide material LiNi0.48Co0.18Mn0.3Mg0.02Ti0.02O2 has been synthesized via a co-precipitation assisted solid-phase method, and its crystal structure, morphology and electrochemical properties have been systematically investigated. Rietveld refinement of its X-ray diffraction data indicates a higher degree of the well-ordered crystallographic form, which provides LiNi0.48Co0.18Mn0.3Mg0.02Ti0.02O2 with superior cycle performance and rate capability. The initial discharge capacities of the electrode are 151.5 mA h g−1, 140.1 mA h g−1, 137.1 mA h g−1, 125.2 mA h g−1 and 115.3 mA h g−1 at the current of 0.5C, 1C, 2C, 3C and 5C, respectively. After 100 cycles at the same rates, 94%, 96%, 96%, 94% and 93% of the initial discharge capacity are retained. The improved electrochemical properties are attributed to the decrease in particle size and suppression of cation mixing due to doping with Mg and Ti. The results of this work indicate that LiNi0.48Co0.18Mn0.3Mg0.02Ti0.02O2 is a promising cathode material for Li-ion batteries.