Showing papers by "Bing Ding published in 2018"

Confined Self-Assembly in Two-Dimensional Interlayer Space: Monolayered Mesoporous Carbon Nanosheets with In-Plane Orderly Arranged Mesopores and a Highly Graphitized Framework

Abstract: Although two-dimensional (2D) carbon materials are widely investigated, a well-defined 2D carbon nanosheet with an ordered mesostructure has rarely been realized. Monolayer-ordered mesoporous carbon nanosheets (OMCNS) were prepared through confinement assembly of resol and F127 in the interlayer of montmorillonite (MONT). The nanoscale distance of the interlayer space of MONT only allow the assembly of resol and F127 in the same plane, leading to ordered mesopores perpendicular to carbon nanosheets, and favor the formation of sp2 carbon, resulting in a high degree of graphitization. The mesopores on the carbon nanosheets provide efficient ion diffusion, and the high degree of graphitization provides a fast electron-transport route, enabling OMCNS as excellent electrode materials for electric double layer capacitors.

Significant Effect of Pore Sizes on Energy Storage in Nanoporous Carbon Supercapacitors

Abstract: Mesoporous carbon can be synthesized with good control of surface area, pore-size distribution, and porous architecture. Although the relationship between porosity and supercapacitor performance is well known, there are no thorough reports that compare the performance of numerous types of carbon samples side by side. In this manuscript, we describe the performance of 13 porous carbon samples in supercapacitor devices. We suggest that there is a "critical pore size" at which guest molecules can pass through the pores effectively. In this context, the specific surface area (SSA) and pore-size distribution (PSD) are used to show the point at which the pore size crosses the threshold of critical size. These measurements provide a guide for the development of new kinds of carbon materials for supercapacitor devices.

Superlithiated Polydopamine Derivative for High-Capacity and High-Rate Anode for Lithium-Ion Batteries

Abstract: Organic electrode materials, with low-cost synthesis and environmental friendliness, have gained significant research interest in lithium-ion batteries (LIBs). Polydopamine (PDA), as a bioderived organic electrode material, exhibits a low capacity of ∼100 mAh g-1, greatly limiting the practical application in LIBs. In this work, we find that a simple heat treatment at 300 °C can endow PDA-derived material (PDA300) with superior electrochemical performance. The obtained PDA300 electrode exhibits an ultrahigh capacity of 977 mAh g-1 at 50 mA g-1. Further combining the PDA300 with highly conductive Ti3C2T x MXene, the obtained PDA300/Ti3C2T x composite is demonstrated by high capacity (1190 mAh g-1, 50 mA g-1), excellent rate capability (remaining 552 mAh g-1 at 5 A g-1), and good cycling stability (82% retaining after 1000 cycles). The outstanding lithium storage performance is highly associated with the superlithiation process of the unsaturated carbon-carbon bonds in the PDA derivative and the introduction of the highly conductive Ti3C2T x substrate with a unique two-dimensional nanostructure. This work will provide new opportunities for the expansion of high-performance organic anodes for LIBs.

Self-Template-Directed Metal-Organic Frameworks Network and the Derived Honeycomb-Like Carbon Flakes via Confinement Pyrolysis.

Abstract: Metal-organic frameworks (MOFs) have become a research hotspot since they have been explored as convenient precursors for preparing various multifunctional nanomaterials. However, the preparation of MOF networks with controllable flake morphology in large scale is not realized yet. Herein, a self-template strategy is developed to prepare MOF networks. In this work, layered double-metal hydroxide (LDH) and other layered metal hydroxides are used not only as a scaffold but also as a self-sacrificed metal source. After capturing the abundant metal cations identically from the LDH by the organic linkers, MOF networks are in situ formed. It is interesting that the MOF network-derived carbon materials retain the flake morphology and exhibit a unique honeycomb-like macroporous structure due to the confined shrinkage of the polyhedral facets. The overall properties of the carbon networks are adjustable according to the tailored metal compositions in LDH and the derived MOFs, which are desirable for target-oriented applications as exemplified by the electrochemical application in supercapacitors.

Hierarchically Porous Multilayered Carbon Barriers for High-Performance Li-S Batteries.

Abstract: As one of the most promising energy storage devices, the practical application of lithium-sulfur batteries is limited by the low electrical conductivity of sulfur and the notable "shuttle effects" of sulfur-based electrodes. In this work, we describe a hierarchically porous N-doped zeolitic imidazolate framework-8 (ZIF-8)-derived carbon nanosphere (N-ZDC) with an outer shell and an inner honeycomb-like interconnected nanosheet network as sulfur host material for high-performance and long-term lithium-sulfur batteries. The N-ZDC serves as multilayered barrier against the dissolution of lithium polysulfides. The porously inner interconnected carbon network of the N-ZDC facilitates the electron and ion transportation, ensures a high sulfur loading, and accommodates a volume expansion of the sulfur species. As a result, the optimized N-ZDC4 /S electrodes displayed high initial specific capacities of 1343, 1182, and 698 mAh g-1 at 0.5, 1, and 2 C, respectively, and an ultraslow capacity decay of only 0.048 % per cycle at 2 C over 800 cycles. Even with a high sulfur loading of 3.1 mg cm-2 , N-ZDC4 /S still delivered a reversible capacity of 956 mAh g-1 and stabilizes at 544 mAh g-1 after 500 cycles at 0.5 C, revealing the great potential of the novel carbon nanospheres for energy storage application.