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A novel approach is developed to synthesize a nitrogen-doped porous Co3O4/anthracite-derived graphene (Co3O4/AG) nanocomposite through a combined self-assembly and heat treatment process using resource-rich anthracite as a carbonaceous precursor. The nanocomposite contains uniformly distributed Co3O4 nanoparticles with a size smaller than 8 nm on the surface of porous graphene, and exhibits a specific surface area (120 m2·g−1), well-developed mesopores distributed at 3~10 nm, and a high level of nitrogen doping (5.4 at. %). These unique microstructure features of the nanocomposite can offer extra active sites and efficient pathways during the electrochemical reaction, which are conducive to improvement of the electrochemical performance for the anode material. The Co3O4/AG electrode possesses a high reversible capacity of 845 mAh·g−1 and an excellent rate capacity of 587 mAh·g−1. Furthermore, a good cyclic stability of 510 mAh·g−1 after 100 cycles at 500 mA·g−1 is maintained. Therefore, this work could provide an economical and effective route for the large-scale application of a Co3O4/AG nanocomposite as an excellent anode material in lithium-ion batteries. [ABSTRACT FROM AUTHOR]

Constructing porous structure and surface modification are effective ways to enhance the Li-ion storage performance of commercial graphite anode for lithium-ion batteries (LIBs). Herein, nitrogen, oxygen and phosphorus ternary-doped coal-based hierarchical porous carbon networks (N/O/P-CCNs) were prepared through liquid oxidation combined with self-assembly method. The N/O/P-CCNs have a three-dimensional porous carbon network structure formed by cross-linking carbon nanosheets with an appropriate specific surface area (321 m2 g−1) and distribution of micro-, meso- and macropore, while the surfaces of carbon nanosheets are doped with nitrogen, oxygen and phosphorus. Due to unique hierarchical porous structure and the synergistic effect of ternary doping, the N/O/P-CCNs anode exhibits excellent Li-ion storage properties with initial reversible capacity of 1079 mAh g−1, which is much higher than that of coal-based graphite anode (382 mAh g−1). Besides, the N/O/P-CCNs anode also has superior rate capability (336 and 275 mAh g−1 at 1.0 and 2.0 A g−1) and cycle stability with a high capacity retention (near 100 % after 100 cycles). The excellent electrochemical performance is not only related to the hierarchical pore structure that can provide efficient channels for lithium-ion transport, but also to the ternary-doping of nitrogen, oxygen and phosphorus that can provide more active sites for lithium-ion storage and enhance conductivity. This work provides a novel and effective design strategy for developing high-performance anode materials for LIBs. • The N/O/P-CCNs were synthetized by liquid oxidation combined with self-assembly method. • The N/O/P-CCNs possess unique 3D hierarchical porous network structure with a reasonable specific surface area. • The synergistic effect of nitrogen, oxide and phosphorus ternary-doping provides more active sites for lithium-ion storage. • The N/O/P-CCNs as anode for LIBs exhibit excellent lithium storage properties. [ABSTRACT FROM AUTHOR]

Abstract Adopting an impregnation strategy, the homogeneous and efficient pore-creating are simultaneously achieved by one-pot KOH activation making full use of the swelling feature of hydrophilic soybean protein gels in alkaline solution. N, O co-doped porous carbons (NOPCs) have been fabricated using soybean meal as carbon, nitrogen and oxygen sources for an abundance of protein with a smaller amount of corrosive KOH. The as-obtained NOPCs exhibit advantageous characteristics for electrochemical energy storage including unique honeycomb-like morphology with interconnected carbon frameworks, high specific surface area, hierarchical porosity and controllable surface chemistry, which provides a large number of favorable nanochannels with suitable surface property for fast electrolyte diffusion and efficient electron transfer in the carbon networks. When tested as supercapacitor electrodes with symmetric configuration in 3 M KOH electrolyte, the NOPC-700 electrode prepared at 700 °C with a KOH/soybean meal mass ratio of 0.25 presents a high specific capacitance (330 F g−1 at 0.5 A g−1), remarkable cycling stability (94.6% capacitance retention after 10000 cycles at 2.5 A g−1), and superior rate capability (270 F g−1 at 5 A g−1). Furthermore, the NOPC-700//NOPC-700 supercapacitor delivers a maximum energy density of 8.4 Wh kg−1. The coordination between protein-rich soybean meal and one-pot KOH activation plays an important role in efficiently synthesizing porous carbons with robust energy storage performance for supercapacitors. Graphical abstract Image 1 Highlights • Soybean meal possesses the swelling feature when impregnated in KOH solution. • N and O co-doped porous carbon (NOPCs) were prepared by one-pot KOH activation. • NOPCs show high specific surface area and well-designed hierarchical porosity. • NOPCs have uniform nitrogen and oxygen functional groups in framework. • Supercapacitors with NOPCs as electrodes show superior capacitive behaviors. [ABSTRACT FROM AUTHOR]