Showing papers by "Bing Ding published in 2017"

Biomass derived carbon for energy storage devices

Abstract: Electrochemical energy storage devices are becoming increasingly more important for reducing fossil fuel energy consumption in transportation and for the widespread deployment of intermittent renewable energy. The applications of different energy storage devices in specific situations are all primarily reliant on the electrode materials, especially carbon materials. Biomass-derived carbon materials are receiving extensive attention as electrode materials for energy storage devices because of their tunable physical/chemical properties, environmental concern, and economic value. In this review, recent developments in the biomass-derived carbon materials and the properties controlling the mechanism behind their operation are presented and discussed. Moreover, progress on the applications of biomass-derived carbon materials as electrodes for energy storage devices is summarized, including electrochemical capacitors, lithium–sulfur batteries, lithium-ion batteries, and sodium-ion batteries. The effects of the pore structure, surface properties, and graphitic degree on the electrochemical performance are discussed in detail, which will guide further rational design of the biomass-derived carbon materials for energy storage devices.

Hierarchical porous carbons with layer-by-layer motif architectures from confined soft-template self-assembly in layered materials.

Abstract: Although various two-dimensional (2D) nanomaterials have been explored as promising capacitive materials due to their unique layered structure, their natural restacking tendency impedes electrolyte transport and significantly restricts their practical applications. Herein, we synthesize all-carbon layer-by-layer motif architectures by introducing 2D ordered mesoporous carbons (OMC) within the interlayer space of 2D nanomaterials. As a proof of concept, MXenes are selected as 2D hosts to design 2D-2D heterostructures. Further removing the metal elements from MXenes leads to the formation of all-carbon 2D-2D heterostructures consisting of alternating layers of MXene-derived carbon (MDC) and OMC. The OMC layers intercalated with the MDC layers not only prevent restacking but also facilitate ion diffusion and electron transfer. The performance of the obtained hybrid carbons as supercapacitor electrodes demonstrates their potential for upcoming electronic devices. This method allows to overcome the restacking and blocking of 2D nanomaterials by constructing ion-accessible OMC within the 2D host material.

Pseudocapacitive materials for electrochemical capacitors: from rational synthesis to capacitance optimization

Abstract: Among various energy-storage devices, electrochemical capacitors (ECs) are prominent power provision but show relatively low energy density. One way to increase the energy density of ECs is to move from carbon-based electric double-layer capacitors to pseudocapacitors, which manifest much higher capacitance. However, compared with carbon materials, the pseudocapacitive electrodes suffer from high resistance for electron and/or ion transfer, significantly restricting their capacity, rate capability and cyclability. Rational design of electrode materials offers opportunities to optimize their electrochemical performance, leading to devices with high energy density while maintaining high power density. This paper reviews the different approaches of electrodes striving to advance the energy and power density of ECs.

MoS2-Nanosheet-Decorated 2D Titanium Carbide (MXene) as High-Performance Anodes for Sodium-Ion Batteries

Abstract: Sodium-ion batteries (SIBs) are a promising alternative to lithium-ion batteries for large-scale energy storage applications. The intriguing 2D transition-metal carbides/carbonitrides, also called MXenes, are increasingly being investigated as anodes as for SIB applications, owing to the merits of their metallic conductivity, low diffusion barrier for Na+, and good mechanical properties. However, the issue of low specific capacity has proven to be a difficult challenge to overcome. Herein, we synthesize a composite of MoS2/Ti3C2Tx to improve the ion accessibility of MXene layers by increasing the interlayer space and boost its specific capacity, where the MoS2 nanosheets are intercalated between Ti3C2Tx layers through a hydrothermal route. When tested as a SIB anode, the MoS2/Ti3C2Tx composite yielded a high specific capacity of 250.9 mAh g−1 over 100 cycles. More remarkably, the MoS2/Ti3C2Tx electrode displayed an exceeding rate performance with a capacity of 162.7 mAh g−1 at 1 A g−1.

Co3O4 nanoneedle arrays as a multifunctional “super-reservoir” electrode for long cycle life Li–S batteries

Abstract: Lithium–sulfur (Li–S) batteries are highly attractive as energy storage devices due to their low cost and high energy density. The undesired capacity degradation caused by the polysulfide shuttle, however, has hindered their commercialization. Herein, a Co3O4 nanoneedle array on carbon cloth (CC@Co3O4) nanocomposite has been prepared and demonstrated for the first time as a multifunctional “super-reservoir” electrode to prolong the cycle life of Li–S batteries. Owing to the polar surface of the Co3O4 nanoneedle array, soluble lithium polysulfides (Li2Sn, 4 < n < 8) can be effectively absorbed and then transformed to insoluble Li2S2/Li2S which evenly covers the surface of the Co3O4 nanoneedle during the discharge process. Further, during the charge process, the Co3O4 nanoneedle can catalyze the electrochemical transformation of Li2S2/Li2S into soluble polysulfides. A high initial capacity of 1231 mA h g−1 at 0.5C and a slow capacity decay of 0.049%/cycle at 2.0C over 500 cycles were achieved; excellent rate performance was also obtained.

Highly stable lithium ion capacitor enabled by hierarchical polyimide derived carbon microspheres combined with 3D current collectors

Abstract: Lithium ion capacitors (LICs), which combine the merits of both lithium ion batteries and supercapacitors, have recently attracted considerable attention. However, LICs generally use different materials and synthesis routes for the cathode and anode, resulting in a complicated process and high production cost, from an energy storage device perspective. In addition, the current collector interface structure design plays a key role in the electrochemical process. Herein, we have designed and fabricated a novel LIC with similar-symmetric architecture in both electrodes. The nitrogen-doped porous carbon microspheres (NPCM) derived from the hierarchical assembly of polyimide nanosheets as the anode material showed excellent lithium storage properties. The cathode material (NPCM-A) obtained by the activation of NPCM led to an ultrahigh specific surface area (2007 m2 g−1) and excellent capacitance characteristics. Benefiting from the unique superstructure and 3D porous array current collectors, the novel LIC achieved a high energy density of 95.08 W h kg−1 and could retain 48.2 W h kg−1 even at a high power density of 15 kW kg−1 on the basis of mass of both electrodes. Moreover, the LIC achieved 80.1% capacity retention after 5000 ultra-long cycles, corresponding to fading of 0.004% per cycle.

Highly Conductive and Lightweight Composite Film as Polysulfide Reservoir for High-Performance Lithium–Sulfur Batteries

Abstract: Lithium–sulfur (Li−S) batteries are one of the most promising candidates for the next generation of energy-storage devices owing to their high theoretical energy and low cost. However, low practical energy density and poor cycling life are obstacles to the practical application of Li−S batteries. A highly conductive and lightweight poly(3,4-ethylenedioxythiophene):polystyrene sulfonate–carbon nanotube (PEDOT:PSS-CNT) interlayer for Li−S batteries has been fabricated. The PEDOT:PSS-CNT interlayer not only acts as a soft buffer to scavenge excess lithium polysulfides in the pores and restricts polysulfides from migrating to the lithium anode by chemical absorption, but also serves as an assisted “current collector” to improve the electronic conductivity for the sulfur cathode. With these synergistic contributions, pure sulfur cathode with the PEDOT:PSS-CNT interlayer shows a high capacity (921 mA h g−1at 0.5 C; 1 C=1675 mA h g−1), enhanced cycling performance (a capacity retention of 70.9 % after 200 cycles), and good rate performance. The excellent electrochemical performance of the sulfur cathode plus the easy fabrication of such a functional interlayer bring feasible Li−S batteries for practical applications one step closer.

Nitrogen-Doped Porous Carbon Nanospheres from Natural Sepia Ink: Easy Preparation and Extraordinary Capacitive Performance

Abstract: Heteroatom-doped nanostructured porous carbons have attracted intensive attention for electrical-double layer capacitors (EDLCs) because of their large surface area and surface functionalization. Here we use biowaste sepia ink as a sustainable source to synthesize nitrogen-doped highly porous carbon nanospheres by a simple molten salt-based activation strategy. The introduction of molten salt is not only beneficial for repairing the carbon conjugate network, but can also further improve the activation effect of porogen. The as-obtained carbon nanospheres (MA-NCS) displayed a large surface area of 1760 m2 g−1, optimized pore architecture, and high nitrogen content (8.6 wt %). With this design, the MA-NCS as EDLCs electrode exhibited a remarkable specific capacitance of 320 F g−1 at the current density of 0.5 A g−1 and high rate capability in 6 m KOH electrolyte. Furthermore, the assembled EDLCs demonstrated a high specific capacitance of 130 F g−1 at 0.5 A g−1 in an organic electrolyte (1 m TEABF4/AN), obtaining a maximum energy density of 28.2 Wh kg−1 at a power density of 625 W kg−1. This novel biowaste precursor-synthesis route presents great potential for facile large-scale production of high-performance porous carbons for green and long-term energy storage.