Gemeng Liang

Breathable and Wearable Energy Storage Based on Highly Flexible Paper Electrodes.

Breathable and wearable energy storage is achieved based on an innovative design solution. Carbon nanotube/MnO2 -decorated air-laid paper electrodes, with outstanding flexibility and good electrochemical performances, are prepared. They are then assembled into solid-state supercapacitors. By making through-holes on the supercapacitors, breathable and flexible supercapacitors are successfully fabricated.

Suppressing Self-Discharge and Shuttle Effect of Lithium–Sulfur Batteries with V2O5-Decorated Carbon Nanofiber Interlayer

V2 O5 decorated carbon nanofibers (CNFs) are prepared and used as a multifunctional interlayer for a lithium-sulfur (Li-S) battery. V2 O5 anchored on CNFs can not only suppress the shuttle effect of polysulfide by the strong adsorption and redox reaction, but also work as a high-potential dam to restrain the self-discharge behavior in the battery. As a result, Li-S batteries with a high capacity and long cycling life can be stored and rested for a long time without obvious capacity fading.

Ultrafine TiO2 Decorated Carbon Nanofibers as Multifunctional Interlayer for High-Performance Lithium–Sulfur Battery

Although lithium-sulfur (Li-S) batteries deliver high specific energy densities, lots of intrinsic and fatal obstacles still restrict their practical application. Electrospun carbon nanofibers (CNFs) decorated with ultrafine TiO2 nanoparticles (CNF-T) were prepared and used as a multifunctional interlayer to suppress the volume expansion and shuttle effect of Li-S battery. With this strategy, the CNF network with abundant space and superior conductivity can accommodate and recycle the dissolved polysulfides for the bare sulfur cathode. Meanwhile, the ultrafine TiO2 nanoparticles on CNFs work as anchoring points to capture the polysulfides with the strong interaction, making the battery perform with remarkable and stable electrochemical properties. As a result, the Li-S battery with the CNF-T interlayer delivers an initial reversible capacity of 935 mA h g(-1) at 1 C with a capacity retention of 74.2% after 500 cycles. It is believed that this simple, low-cost and scalable method will definitely bring a novel perspective on the practical utilization of Li-S batteries.

Cyclized-polyacrylonitrile modified carbon nanofiber interlayers enabling strong trapping of polysulfides in lithium–sulfur batteries

Lithium–sulfur (Li–S) batteries are seriously constrained by the diffusion and crossover of intermediary product polysulfides and their further reductions on the anode surface. Although carbon-based interlayers have been widely used to inhibit the detrimental shuttle effect in Li–S batteries, the weak physical adsorption of pure carbon materials for trapping polysulfides still leads to low recycle efficiency of active species and short cycle life for cells. Herein, we report a cyclized-polyacrylonitrile-cast carbon nanofiber (CP@CNF) film as an interlayer in Li–S batteries. By exploiting the CP@CNF interlayer, the batteries assembled with bare sulfur cathodes deliver superior rate capability and cycle stability. The reversible capacity could be maintained at 710 mA h g−1 after 200 cycles at 0.3C and a capacity of 560 mA h g−1 can be obtained even at a 2C rate. The improved performances are attributed to both the abundant pyridine groups in the cyclized polyacrylonitrile matrix, which can entrap polysulfides by strong interatomic attraction, and the three-dimensional porous conductive network composed of the carbon nanofiber skeleton and conjugated polymer matrix, giving rise to highly effective transfer pathways for electrons and ions.

An interwoven MoO3@CNT scaffold interlayer for high-performance lithium–sulfur batteries

Lithium–sulfur (Li–S) batteries have attracted increasing attention in the past few decades due to the extremely high energy density, low cost and non-toxicity of sulfur. But the poor conductivity of sulfur and particularly the migration of soluble polysulfides greatly hindered the application of Li–S batteries. Herein, we report a novel strategy for trapping polysulfides by coating a separator with an interwoven framework of MoO3 nanorods and carbon nanotubes (CNTs) as the interlayer in Li–S batteries. The interwoven scaffold-like MoO3@CNT network provides abundant conducting channels and pathways for ions and electrons, leading to high rate capabilities. While the MoO3@CNT interlayer acting as a barrier effectively mitigates the shuttle effect in Li–S batteries, the MoO3 nanorods enfolded by CNTs uniformly play an important role in immobilizing sulfur species. Consequently, the electrochemical performances of Li–S batteries are improved, giving rise to higher capacities with a longer cycling life. The Li–S batteries with the MoO3@CNT interlayer can deliver a specific capacity of 755 mA h g−1 after 200 cycles at a current density of 0.3C, and show an excellent rate capability with a capacity of 655 mA h g−1 at 3C.

Stacking up layers of polyaniline/carbon nanotube networks inside papers as highly flexible electrodes with large areal capacitance and superior rate capability

Developing high-performance flexible film-like electrodes is still a primary task for the practical applications of wearable/portable planar supercapacitors. In this work, a facile and effective approach, i.e., stacking up layers of polyaniline (PANI)/carbon nanotube (CNT) composite networks inside air-laid papers, is proposed to fabricate highly flexible paper electrodes with large areal capacitance and superior rate capability. The layer-by-layer deposition of PANI/CNT networks endows the fabricated paper electrodes with high loading and uniform distribution of PANI; meanwhile, the good electrical conductivity and porous structure of these introduced PANI/CNT networks guarantee sufficient paths for electron movement and ion transportation in the electrodes. Consequently, when 4 layers of PANI/CNT networks (with optimal PANI content) are stacked inside papers, the areal capacitance of the prepared electrode is as high as 1506 mF cm−2 at a charge/discharge current of 10 mA cm−2 and 1298 mF cm−2 at 100 mA cm−2; the electrode also exhibits high flexibility and good cycling stability (with 82% capacitance retention after 11 500 charge/discharge cycles). These merits make our PANI/CNT/papers promising candidates for flexible planar supercapacitor electrodes. Besides, this work is believed to provide a new thought for producing high-loading and high-energy wearable/portable energy storage devices.

Fe3O4-Decorated Porous Graphene Interlayer for High-Performance Lithium–Sulfur Batteries

Lithium-sulfur (Li-S) batteries are seriously restrained by the shuttling effect of intermediary products and their further reduction on the anode surface. Considerable researches have been devoted to overcoming these issues by introducing carbon-based materials as the sulfur host or interlayer in the Li-S systems. Herein, we constructed a multifunctional interlayer on a separator by inserting Fe3O4 nanoparticles (NPs) in a porous graphene (PG) film to immobilize polysulfides effectively. The porous structure of graphene was optimized by controlling the oxidation conditions for facilitating ion transfer. The polar Fe3O4 NPs were employed to trap sulfur species via strong chemical interaction. By exploiting the PG-Fe3O4 interlayer with optimal porous structure and component, the Li-S battery delivered a superior cycling performance and rate capability. The reversible discharge capacity could be maintained at 732 mAh g-1 after 500 cycles and 356 mAh g-1 after total 2000 cycles at 1 C with a final capacity retention of 49%. Moreover, a capacity of 589 mAh g-1 could also be maintained even at 2 C rate.