One great challenge in the development of lithium ion batteries is to simultaneously achieve high power and large energy capacity at fast charge and discharge rates for several minutes to seconds. Here we show that nitrogen- or boron-doped graphene can be used as a promising anode for high-power and high-energy lithium ion batteries under high-rate charge and discharge conditions. The doped graphene shows a high reversible capacity of >1040 mAh g(-1) at a low rate of 50 mA g(-1). More importantly, it can be quickly charged and discharged in a very short time of 1 h to several tens of seconds together with high-rate capability and excellent long-term cyclability. For example, a very high capacity of ∼199 and 235 mAh g(-1) was obtained for the N-doped graphene and B-doped graphene at 25 A g(-1) (about 30 s to full charge). We believe that the unique two-dimensional structure, disordered surface morphology, heteroatomic defects, better electrode/electrolyte wettability, increased intersheet distance, improved electrical conductivity, and thermal stability of the doped graphene are beneficial to rapid surface Li(+) absorption and ultrafast Li(+) diffusion and electron transport, and thus make the doped materials superior to those of pristine chemically derived graphene and other carbonaceous materials.

We report a facile strategy to synthesize the nanocomposite of Co3O4 nanoparticles anchored on conducting graphene as an advanced anode material for high-performance lithium-ion batteries. The Co3O4 nanoparticles obtained are 10−30 nm in size and homogeneously anchor on graphene sheets as spacers to keep the neighboring sheets separated. This Co3O4/graphene nanocomposite displays superior Li-battery performance with large reversible capacity, excellent cyclic performance, and good rate capability, highlighting the importance of the anchoring of nanoparticles on graphene sheets for maximum utilization of electrochemically active Co3O4 nanoparticles and graphene for energy storage applications in high-performance lithium-ion batteries.

Three-dimensional (3D) N-doped graphene aerogel (N-GA)-supported Fe(3)O(4) nanoparticles (Fe(3)O(4)/N-GAs) as efficient cathode catalysts for the oxygen reduction reaction (ORR) are reported. The graphene hybrids exhibit an interconnected macroporous framework of graphene sheets with uniform dispersion of Fe(3)O(4) nanoparticles (NPs). In studying the effects of the carbon support on the Fe(3)O(4) NPs for the ORR, we found that Fe(3)O(4)/N-GAs show a more positive onset potential, higher cathodic density, lower H(2)O(2) yield, and higher electron transfer number for the ORR in alkaline media than Fe(3)O(4) NPs supported on N-doped carbon black or N-doped graphene sheets, highlighting the importance of the 3D macropores and high specific surface area of the GA support for improving the ORR performance. Furthermore, Fe(3)O(4)/N-GAs show better durability than the commercial Pt/C catalyst.

Mass production of high-quality graphene sheets is essential for their practical application in electronics, optoelectronics, composite materials, and energy-storage devices. Here we report a prompt electrochemical exfoliation of graphene sheets into aqueous solutions of different inorganic salts ((NH4)2SO4, Na2SO4, K2SO4, etc.). Exfoliation in these electrolytes leads to graphene with a high yield (>85%, ≤3 layers), large lateral size (up to 44 μm), low oxidation degree (a C/O ratio of 17.2), and a remarkable hole mobility of 310 cm(2) V(-1) s(-1). Further, highly conductive graphene films (11 Ω sq(-1)) are readily fabricated on an A4-size paper by applying brush painting of a concentrated graphene ink (10 mg mL(-1), in N,N'-dimethylformamide). All-solid-state flexible supercapacitors manufactured on the basis of such graphene films deliver a high area capacitance of 11.3 mF cm(-2) and an excellent rate capability of 5000 mV s(-1). The described electrochemical exfoliation shows great promise for the industrial-scale synthesis of high-quality graphene for numerous advanced applications.