Lithium–sulfur (Li–S) batteries are next-generation energy storage systems with high energy density, and the rate performance is a very important consideration for practical applications. Recent approaches such as introducing catalytic materials to facilitate polysulfide conversion have been explored, yet the results remain unsatisfactory. Here, we present an optimized Li–S electrode featured by a large amount of highly dispersed Co3S4 nanoparticles (∼10 nm in size) throughout a hierarchical carbon nanostructure hybridized from ZIF-67 and carbon nanotube (CNT) sponge. This enables homogeneous distribution and close contact between infiltrated sulfur and Co3S4 nanoparticles within the ZIF-67-derived N-doped carbon nanocubes, leading to effective chemical interaction with polysulfides, maximum catalytic effect and enhanced lithium ion diffusion, while the built-in three-dimensional CNT network ensures high electrical conductivity of the electrode. As a consequence, the Li–S battery exhibits both extraordinary rate performance by maintaining a capacity of ∼850 mAh g–1 at very high charge/discharge rate (5 C) and long-term cycling stability with 85% retention after 1000 cycles at 5 C (an average capacity fading rate of only 0.0137% per cycle).
An efficient manner to produce strained atomic structures, is fabricating catalysts with defect-rich atomic structures, including surface defects (such as surface vacancy, doping,) and bulk defects (such as dislocations and grain boundary). [3] Traditional methods to synthesize strain-effected structures, including polyol synthesis, seed-mediated growth, galvanic replacement, electrochemical dealloying, and thermal annealing-induced segregation, [2i,4] are complex and time-consuming processes, which hinder the manufacturing efficiency and limit the wide application of strain-effected catalysts. In addition, strain-induced high-energy surface structures arising from bulk defects, such as dislocations or grain boundary, are more likely to be resistant to surface restructuring during catalysis. [5] It is generally accepted that non-equilibrium conditions tend to induce plentiful defects, so we seek to employ a synthesis method in an extreme environment to realize bulk-defect-strained structures of electrocatalysts. Recently, our group developed a thermal shock nanomanufacturing method which showed enormous potential and achieved great progresses in ultrafast fabrication of nanoparticles, nanowires, graphene, and more. [6] Since the thermal shock process was invented, the method has been widely used in nanomaterials production. [6a-e,7] However, few studies focused on how Designing high-performance and low-cost electrocatalysts is crucial for the electrochemical production of hydrogen. Dislocation-strained IrNi nanoparticles loaded on a carbon nanotube sponge (DSIrNi@CNTS) driven by unsteady thermal shock in an extreme environment are reported here as a highly efficient hydrogen evolution reaction (HER) catalyst. Experimental results demonstrate that numerous dislocations are kinetically trapped in self-assembled IrNi nanoparticles due to the ultrafast quenching and different atomic radii, which can induce strain effects into the IrNi nanoparticles. Such strain-induced highenergy surface structures arising from bulk defects (dislocations), are more likely to be resistant to surface restructuring during catalysis. The catalyst exhibits outstanding HER activity with only 17 mV overpotential to achieve 10 mA cm −2 in an alkaline electrolyte with fabulous stability, exceeding state-of-the-art Pt/C catalysts. These density functional theory results demonstrate that the electronic structure of as-synthesized IrNi nanostructure can be optimized by the strain effects induced by the dislocations, and the free energy of HER can be tuned toward the optimal region. Hydrogen, as a clean energy source with a high energy density, opens up the opportunities of renewable energy and traditional fossil energy, increasing the diversification of energy sources. [1] Nevertheless, the improvement of hydrogen production is limited toward overpotential and stability due to the intrinsically sluggish kinetics of the hydrogen evolution reaction (HER). Strain engineering, which can optimize the electronic structure and chemical activity of the ...
Carbon nanotube functional materials (CNTFMs) represent an important research field in transforming nanoscience and nanotechnology into practical applications, with potential impact in a wide realm of science, technology, and engineering. In this review, we combine the state-of-the-art research activities of CNTFMs with the application prospect, to highlight critical issues and identify future challenges. We focus on macroscopic long fibers, thin films, and bulk sponges which are typical CNTFMs in different dimensions with distinct characteristics, and also cover a variety of derived composite/hierarchical materials. Critical issues related to their structures, properties, and applications as robust conductive skeletons or high-performance flexible electrodes in mechanical and electronic devices, advanced energy conversion and storage systems, and environmental areas have been discussed specifically. Finally, possible solutions and directions are proposed for overcoming current obstacles and promoting future efforts in the field.
Densely packed metal–organic framework (MOF) and carbon nanotube (CNT) hybrid materials with tailored hierarchical porous structures are prepared by in situ growth and room temperature drying/shrinking for high-performance compact energy storage systems.
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