Interconnected Carbon Network Research Articles

NaCl-template-assisted freeze-drying synthesis of 3D porous carbon-encapsulated V2O3 for lithium-ion battery anode

Vanadium trioxide material have attracted enormous attention recently, owing to their high theoretical capacity for use as anodes in lithium ion batteries. However, the unstable structure of V2O3 limits its practical application. It is challenge to develop a simple, scalable and economical technique to produce 3D porous carbon-based V2O3 materials with high structure stability. In this work, a facile NaCl template-assisted freeze-drying strategy was used to produce 3D porous carbon-encapsulated V2O3 (3D porous V2O3@C) composites with highly crystalline architecture, uniformly carbon-encapsulated V2O3 nanoparticles and interconnected conductive carbon networks. The resultant 3D porous V2O3@C anode exhibits significantly enhanced rate performance (797 mAh/g at 0.1 A/g, 715 mAh/g at 0.3 A/g, 658 mAh/g at 0.5 A/g, 598 mAh/g at 1 A/g, 480 mAh/g at 3 A/g and 426 mAh/g at 5 A/g) and long-term cycling stability (506 mAh/g at 5A/g after 2000 cycles). The present work suggests a scalable preparation of the 3D porous carbon-based V2O3 materials, which may be extended to preparing other 3D porous materials for potential applications in energy storage, catalysis and sensors.

Facile synthesis of interconnected carbon network decorated with Co3O4 nanoparticles for potential supercapacitor applications

Three-dimensional (3D) multifunctional carbon nanofibers (CNFs) are promising electrode materials of electrochemical energy storage devices for their unique interconnect structures. Here, we prepared interconnected carbon network decorated with Co3O4 nanoparticles by a facile soak-adsorption strategy. Among them, bacterial cellulose (BC) with inherent interconnect structures was used as carbon precursor. The adsorbed organophosphorus pesticides can introduce new functional groups on the surface of BC and create loose structure for fabricating a loose 3D CNFs skeleton. The absorbed cobalt salt transformed into Co3O4 nanoparticles which anchored on the CNF skeleton to obtain CNFs/Co3O4 composites. This strategy combines interconnected CNFs and uniformly distributed Co3O4 nanoparticles which provide large specific surface area, fast electron transport, well mechanical stability and high electrochemical activity. The CNFs/Co3O4 electrode exhibits a high specific capacitance (785 F g−1 at 0.5 A g−1), superior rate performance (capacity remained 57% from 0.5 to 20 A g−1) and good cycling stability (over 93.0% capacity retained after 5000 cycles). Furthermore, the assembled asymmetric device CNFs/Co3O4//activated carbon (AC) possesses a high energy density of 13 Wh kg−1 at the power density of 257 W kg−1 and the performance still retains 85.9% of initial capacity after 10,000 cycles.

Porous nitrogen-doped carbon networks derived from orange peel for high-performance supercapacitors

A novel type of porous nitrogen-doped carbon networks derived from a green biomass-waste (orange peel) by integrated carbonization, activation, and nitrogen-doped processes using FeCl3 as activating agent and urea as nitrogen precursor and gasification expander. The porous nitrogen-doped orange peel-based carbon networks (PN-OPC) possessed interconnected porous carbon networks morphology, high specific surface area (1514.2 m2 g−1), reasonable pore size (2.9 nm), and high nitrogen content (about 7.8 wt%). This unique porous network structure and rich nitrogen-dopant leads to fast penetration of electrolyte ions and transmission of electrons, which endow the PN-OPC electrode material with high specific capacitance of 255 F g−1 at current density of 0.5 A g−1 and superior rate capability in 6 mol L−1 KOH aqueous electrolyte. Moreover, the symmetric supercapacitor based on PN-OPC electrode exhibits high specific energy of 16 Wh kg−1 at specific power of 400 W kg−1 operated in the voltage range 0–1.6 V in 0.5 M Li2SO4 aqueous electrolyte, and impressive cyclic stability with 96% after 5000 charge/discharge cycles. Therefore, the present work will open a new strategy to design and fabricate novel porous nitrogen-doped carbon network electrode materials for high-performance supercapacitor.

Template‐Induced Self‐Activation Route for Hierarchical Porous Carbon Derived from Interpenetrating Polymer Networks as Electrode Material for Supercapacitors

AbstractHierarchical porous textures of carbon‐based electrode materials are advantageous for applications in supercapacitors, owing to their reasonable pore size distribution and large surface area. In this work, a facile yet effective one‐step carbonization method for the preparation of hierarchical porous carbons (HPCs) derived from interpenetrating polymer networks (IPNs) of phenol‐formaldehyde resin (PF) and sodium polyacrylate (PAAS) is proposed. Phenol‐formaldehyde prepolymer can be introduced into the inter network space of PAAS to form IPNs in which only hydrogen‐bonding interactions exist between them. During the carbonization process of IPNs, the PF networks tend to form a carbon matrix, which generates large amounts of micropores. While the PAAS evaporates into gaseous products, serving as a template for micro‐, meso‐, and macropores. Due to such synergistic effects, a carbon material with a large surface area of 1764 m2 g−1 and a large pore volume of 1.111 cm3 g−1 is constructed with an interconnected hierarchical porous carbon network structure. With such unique carbon structure characteristics, the electrode material of HPC delivers a high specific capacitance of 201 F g−1 at 0.5 A g−1 and excellent cyclability of approximately 100 % of capacitance retention after 10000 cycles. The ideal capacitive behavior from IPNs provides new insights for the production of carbonaceous materials for high‐performance supercapacitors applications.

Necklace-like MoC sulfiphilic sites embedded in interconnected carbon networks for Li–S batteries with high sulfur loading

The small MoC nanoparticles grown on the surface of interconnected carbon networks work as effective sulfiphilic sites, helping to achieve a high electrochemical performance for Li–S batteries.

Template synthesis of mesoporous Li2MnSiO4@C composite with improved lithium storage properties

Li2MnSiO4 is considered as a promising cathode candidate for high energy density Lithium-ion batteries (LIBs), due to its high theoretical capacity, favorable working potential as well as the low-cost and non-toxic nature of manganese element. However, it suffers from low capacity utilization and inferior cycling performance, due to the structural rearrangement upon cycling, phase impurities and manganese dissolution. To address these issues, nanostructure construction and carbon coating proves to be effective approach. In this work, we introduce an in situ template synthesis of a phase-pure Li2MnSiO4@C (MP-LMS@C) composite, which exhibits unique mesoporous morphology with nanosized Li2MnSiO4 granules homogenously encapsulated in the interconnected carbon networks. Such unique Li2MnSiO4@C structure not only facilitates electron conduction and Li+ transport, but also suppresses the manganese dissolution, as a result, the mesoporous Li2MnSiO4@C cathode exhibits greatly improved electrochemical performance, with a high specific capacity of 230 mAh g−1, good rate capability and superior capacity retention of 81% over 100 cycles.

In situ growth of amorphous Fe2O3 on 3D interconnected nitrogen-doped carbon nanofibers as high-performance anode materials for sodium-ion batteries

In this work, a novel porous amorphous Fe2O3/nitrogen-doped carbon composite as a promising anode material for sodium-ion batteries has been fabricated by in situ growing amorphous Fe2O3 on 3D interconnected nitrogen-doped carbon nanofibers. The as-prepared composite exhibits superior sodium storage properties. It delivers a high reversible capacity of 408 mA h g−1 after 350 cycles at a current density of 100 mA g−1 and a good rate capability of 183 mA h g−1 at 3 A g−1. The excellent electrochemical performance is owing to the synergistic effects of the amorphous structure of Fe2O3 and the 3D interconnected nitrogen-doped carbon network with high nitrogen doping content (10 atom%), which do not only relieve the internal stress of the electrode and accommodate more electrochemical active sites for Na+ storage, but also buffer the volume changes of amorphous Fe2O3 as well as facilitate the electronic and ionic transportation during cycling.

Compared investigation of carbon-decorated Na3V2(PO4)3 with saccharides of different molecular weights as cathode of sodium ion batteries

A critical issue to boost the development of sodium ion batteries is the development of advanced active materials via meticulous understanding of the synthesis process. The practical application of sodium vanadium phosphate (Na3V2(PO4)3), which shows high energy density, stable structure and excellent thermal properties, is hindered by the intrinsic poor electronic conductivity. Carbon coating was proved to be an effective strategy to cover such pristine limitation and deserved systematic and intensive investigation. Herein, saccharides that widely distributed in nature with different molecular weights were selected to identify the function mechanism of carbon sources in preparing Na3V2(PO4)3@C composite via solid state reaction. Comprehensive and systematic results evidenced that the high polymer starch with glucose polymerization could construct three-dimensional interconnected carbon network, which would boost the electron conductivity and stabilize the structure upon repeated sodium ions insertion/extraction. As a consequence, the extraordinary high rate capability and long-time stability were obtained: a high rate capacity of 72 mA h g−1 could be delivered even at 40 C and the cell retained a capacity retention of 82.8% after 1000 cycles at 1 C. We believe that our work presents here would provide important insights into the carbon coating strategy, which will be favourable for accelerating the commercialization of SIBs.

Effect of carbon sources on morphologies and electrochemical properties of MoS2/carbon composites

Molybdenum disulfide/reduced graphene oxide-carbon (MoS2/RGO-C) and molybdenum disulfide/reduced graphene oxide (MoS2/RGO) composites are synthesized using graphene oxide and glucose as carbon sources, and effects of carbon sources on morphologies and electrochemical properties of MoS2/carbon composites are studied in detail by comparing the materials with pristine MoS2. It demonstrates that after addition of glucose during the synthesis process, MoS2/RGO-C particles grow up due to coating of amorphous carbon on surface, and the coated carbon restrains nanosheet growth of MoS2 crystals. Electrochemical results indicate that incorporation of the reduced graphene oxide and interconnected conductive carbon network improve cycling stability of the MoS2/RGO-C composites, and a capacity retention of 80.5% is obtained after 250 charge/discharge cycles.

Controlled scalable synthesis of yolk-shell structured large-size industrial silicon with interconnected carbon network for lithium storage

Yolk-shell structured nano-Si@void@C can greatly improve the electrical conductivity and buffer the large volume change of silicon nanoparticles, whereas inter poor electrical connection between Si cores and carbon shells still limits the lithium storage performance. Besides, it usually requires complex synthesis conditions and expensive nano-level silicon sources. Herein, we succeed in making the large-size industrial silicon (ca. 400–500 nm) to a yolk-shell structure with a controllable space buffer layer. Most importantly, an interconnected porous carbon network deriving from the thermal decomposition of carbon chains in silicon sources is formed within the carbon shell simultaneously, which can improve the electrical contact between Si cores and hollow carbon shells and prevent the active particles exposure to the electrolyte. With the help of static outer thin carbon shell, optimized inner void and the flexible electrically conductive carbon network, such yolk-shell structured Si@void@C submicron particles synthesizing by one-step carbon-coating procedure exhibit high initial coulomb efficiency of 62%, good rate performance, and excellent long cycling stability with 950.7 mAh g−1 at 100 mA g−1 after 100 cycles. The low consumption and stable synthesis method make it feasible for large-scale fabrication of the yolk-shell structured Si/C composites as commercial anodes for energy storage.

Zn–Air Batteries: Web‐Like Interconnected Carbon Networks from NaCl‐Assisted Pyrolysis of ZIF‐8 for Highly Efficient Oxygen Reduction Catalysis (Small 16/2018)

Zn–Air Batteries: Web‐Like Interconnected Carbon Networks from NaCl‐Assisted Pyrolysis of ZIF‐8 for Highly Efficient Oxygen Reduction Catalysis (Small 16/2018)

3D nanocomposite archiecture constructed by reduced graphene oxide, thermally-treated protein and mesoporous NaTi2(PO4)3 nanocrystals as free-standing electrodes for advanced sodium ion battery

NaTi2(PO4)3 (NTP) with NASICON structure has been regarded as a promising material for sodium-ion batteries (SIBs). However, NTP always exhibits poor cycling stability and rate performance due to slow electronic conductivity. In this work, a free-standing 3D nanocomposite constructed by reduced graphene oxide (rGO), thermally-treated protein (TP) and mesoporous NaTi2(PO4)3 nanocrystals (denoted as MNTP-TP@rGO) is reported. The fabrication includes an electrostatic self-assembly, freeze-drying, mechanical pressing and thermal treatment. In the MNTP-TP@rGO nanocomposite, 3D interconnected carbon network of rGO and TP acts as both a support for the anchored well-distributed MNTP nanocrystals and a current collector. When free-standing MNTP-TP@rGO is used directly as anode in coin-type half-cell, it delivers a high-rate capacity (52.8 mAhg−1 at 50C) and robust cycling stability with the capacity retention of 80% after 1000 cycles at 5C. Furthermore, a full Na-ion battery is constructed using Na3V2(PO4)3/C (NVP/C) as a cathode and free-standing MNTP-TP@rGO as an anode and it exhibits a high specific capacity (58 mAhg−1 at 1C) and outstanding cycling stability (98% capacity retention over 100 cycles at 1C). Our results suggest great potential of the free-standing electrode of MNTP-TP@rGO composite in high-performance SIBs.

Web-Like Interconnected Carbon Networks from NaCl-Assisted Pyrolysis of ZIF-8 for Highly Efficient Oxygen Reduction Catalysis.

The oxygen reduction reaction (ORR) is under intense research due to its significance in energy storage and conversion processes. Recent studies show that interconnected and hierarchically porous structures can further enhance ORR kinetics as well as catalyst durability, but their preparation can be quite time and/or chemical consuming. Here, a simple approach is reported to prepare such complex structures by pyrolyzing composites containing NaCl and ZIF-8. The templating effect of molten NaCl connects ZIF-8 particles into web-like carbon networks. During ORR activity measurements, it achieves a 0.964 V onset potential and a 38 mV dec-1 Tafel slope, which are comparable to those of the benchmark Pt/C (0.979 V and 40 mV dec-1 ). Due to the metal-free feature, this catalyst exhibits a 16 mV shift in half-wave potential after a 10 000-cycle durability test, which is only 60% of that of Pt/C. The catalyst is also tested in Zn-air batteries and the assemblies are able to work at above 1.2 V for 140 h, which triples the life held by those with Pt/C. This study demonstrates a facile strategy to prepare metal-free ORR catalysts with interconnectivity and hierarchical porosity, and proves their great potentials in ORR catalysis and Zn-air batteries.

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

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.

Mesoporous NiCo2O4 nano-needles supported by 3D interconnected carbon network on Ni foam for electrochemical energy storage

In this work, a three dimensional (3D) interconnected carbon network consisting of ultrathin graphite (UG) and carbon nanotubes (CNTs) on Ni foam is fabricated and employed as a novel type of substrate for mesoporous NiCo2O4 nano-needles. The successfully synthesized NiCo2O4 nano-needles/CNTs/UG on Ni foam has many advantages including facile electrolyte access and direct conducting pathways towards current collectors, which enable it to be a promising electrode material in battery-like electrochemical energy storage. Encouragingly, a high capacity of 135.1 mAh/g at the current density of 1 A/g, superior rate performance and also stable cycling for 1200 cycles at the current density of 5 A/g have been demonstrated in this novel material.

Amorphous CuSnO3 nanospheres anchored on interconnected carbon networks for use as novel anode materials for high-performance sodium ion batteries

Bimetal oxide CuSnO3 nanospheres encapsulated in carbon networks were explored as novel anode materials for sodium batteries.

Fabrication of Sn-core/CNT-shell nanocable anchored interconnected carbon networks as anode material for lithium ion batteries

With the assistance of soluble salt template, we designed and synthesized a Sn-core/CNT-shell nanocable anchored interconnected carbon networks structure via a simple CVD process. The Sn nanorods with a diameter of ∼50 nm are protected by ∼3 nm CNTs. The whole hierarchical structure forms a conductive network, which ensures rapid transportation of electrons. As a result, when utilized as lithium-ion battery anode, the 3DC-Sn@CNT electrode exhibits good cycling stability (700 mAh g−1 after 100 cycles at 0.1 A g−1) and rate performance (240 mAh g−1 at 1 A g−1).

Monolithic Hierarchical Carbon Assemblies Embedded with Mesoporous NaTi2(PO4)3 Nanocrystals for Flexible High-Performance Sodium Anodes

Monolithic hierarchical porous carbon assemblies embedded with mesoporous NaTi2(PO4)3 nanocrystals suitable for flexible anodes in sodium ion batteries (SIBs) are prepared by modified vacuum filtration and annealing. The fabrication involves two-step hetero-assembly induced by electrostatic interactions. In the hierarchical porous carbon assembly, the ultrathin amorphous carbon layers connect the mesoporous NaTi2(PO4)3 nanocrystals with the 3D interconnected carbon networks of reduced graphene oxide and carbon nanotubes. Owing to the synergistic effects rendered by the mesoporous nanocrystals and hierarchical porous carbon networks, the unique monolithic assembly provides continuous 3D pathways for electron/ion conduction and enhances the structural stability during repetitive Na insertion/extraction. As a flexible anode in SIBs, it delivers outstanding room-temperature electrochemical performance with high reversible capacity (125mAhg−1 at 1C), long cycling life (82% capacity retention after 5,000 cycles at 10C), as well as high rate capability (73mAhg−1 at 30C). The flexible monolithic anode which exhibits high Coulombic efficiency and reversible capacity at 0°C and 50°C has large potential in flexible high-performance SIBs.

Nitrogen-doped carbon paper with 3D porous structure as a flexible free-standing anode for lithium-ion batteries

In this paper, a novel nitrogen-doped carbon paper (NCP) with both highly dense three-dimensional cellular structure and excellent bending flexibility is fabricated by pyrolyzing a melamine foam under compression. When serving as a free-standing anode for lithium-ion batteries, the NCP electrode delivers a reversible capacity up to 329.8 mA h g−1 after 200 cycles at 0.5 A g−1 (1.34 C) and 126.5 mA h g−1 after 500 cycles at 8.0 A g−1 (21.5 C). Such electrochemical performance is much higher than those of the counterparts prepared by pyrolysis without compression and can be mainly attributed to (a) the 3D highly dense interconnected carbon network with numerous junctions which can facilitate the efficient electron transfer and provide short transportation paths for lithium ions; and (b) the excellent mechanical flexibility and self-standing capability which exempt the use of binder, conductive additive and current collector. The NCP electrode implies a great promise of application in the high-performance Li-ion batteries for the flexible and wearable electronics.

Enhanced Lithium- and Sodium-Ion Storage in an Interconnected Carbon Network Comprising Electronegative Fluorine.

Fluorocarbon (CxFy) anode materials were developed for lithium- and sodium-ion batteries through a facile one-step carbonization of a single precursor, polyvinylidene fluoride (PVDF). Interconnected carbon network structures were produced with doped fluorine in high-temperature carbonization at 500-800 °C. The fluorocarbon anodes derived from the PVDF precursor showed higher reversible discharge capacities of 735 mAh g-1 and 269 mAh g-1 in lithium- and sodium-ion batteries, respectively, compared to the commercial graphitic carbon. After 100 charge/discharge cycles, the fluorocarbon showed retentions of 91.3% and 97.5% in lithium (at 1C) and sodium (at 200 mA g-1) intercalation systems, respectively. The effects of carbonization temperature on the electrochemical properties of alkali metal ion storage were thoroughly investigated and documented. The specific capacities in lithium- and sodium-ion batteries were dependent on the fluorine content, indicating that the highly electronegative fluorine facilitates the insertion/extraction of lithium and sodium ions in rechargeable batteries.