N and S codoping of graphene is realized by a novel approach: covalent functionalization of graphene oxide using 2-aminothiophenol as a source of both N and S followed by thermal treatment. The resulting N- and S-codoped graphene has potential applications in high-performance lithium-ion batteries and as a metal-free catalyst for oxygen reduction reaction.

Elemental sulfur cathodes for lithium/sulfur cells are still in the stage of intensive research due to their unsatisfactory capacity retention and cyclability. The undesired capacity degradation upon cycling originates from gradual diffusion of lithium polysulfides out of the cathode region. To prevent losses of certain intermediate soluble species and extend lifespan of cells, the effective encapsulation of sulfur plays a critical role. Here we report an applicable way, by using thin-layered nickel-based hydroxide as a feasible and effective encapsulation material. In addition to being a durable physical barrier, such hydroxide thin films can irreversibly react with lithium to generate protective layers that combine good ionic permeability and abundant functional polar/hydrophilic groups, leading to drastic improvements in cell behaviours (almost 100% coulombic efficiency and negligible capacity decay within total 500 cycles). Our present encapsulation strategy and understanding of hydroxide working mechanisms may advance progress on the development of lithium/sulfur cells for practical use.

Future development of mini consumer electronics or large electric vehicles/power grids requires Li-ion batteries (LIBs) with not only an outstanding energy-storage performance but also a minimum cost, and the foremost sustainability. Herein, we put forward a smart strategy to convert used disposable bamboo chopsticks into uniform carbon fibers for anodes of LIBs. Bamboo chopsticks waste is recycled and simply treated by a controllable hydrothermal process performed in alkaline solutions, wherein abundant natural cellulose fibers in bamboo in situ get separated and dispersed spontaneously. After carbonization, the evolved carbon fibers exhibit superior anodic performance to the bulky bamboo carbons counterpart, and competitive electrochemical behavior and cost with commercial graphite. The performance of carbon fibers can be further upgraded by growing nanostructured metal oxides (like MnO 2 ) firmly on each fiber scaffold to form a synergetic core-shell electrode architecture. A high reversible capacity of $710 mA h g À1 is maintained without decay up to 300 cycles. Our strategy presents a scalable route to transform chopsticks waste into carbon fibers, offering a very promising way to make sustainable anodes for LIBs and economical multi-functional carbon-based hybrids available for other practical applications. Broader contextLi-ion batteries (LIBs) nowadays play a dominant role on the progress of HEVs/EVs industry. However, despite the ceaseless development of electrode materials selection/manufacturing, current LIBs still show little promise in competing with the traditional gasoline in terms of price, energy, convenience and safety. Besides, the excepted huge exploitation on graphite driven by future demands will eventually one day lead to the depletion of natural graphitic resources. In a long-term perspective, LIBs therefore require to not only possess outstanding energy-storage capability but also be lower-cost and foremost sustainable. We herein propose a smart strategy to convert the used bamboo chopsticks into uniform carbon bers for a sustainable anode of LIBs. Abundant natural bers in chopsticks waste are readily separated and dispersed aer a simple hydrothermal treatment. The derived carbon bers exhibit superior anodic performance as compared to the bulky counterparts, and competitive electrochemical behavior and cost with commercial graphite. Moreover, their performance can be further upgraded by integrating nanostructured metal oxides onto each ber. Our success in the evolution of carbon bers from chopsticks waste may provide a costeffective and sustainable platform for developing advanced carbon-based materials for practical use, not merely in LIBs but also in a wide spectrum of elds. † Electronic supplementary information (ESI) available: SEM images of intermediate products during the ber-extraction process; TEM image of a single carbon ber; optical and SEM images of samples treated in different atmospheres; XRD pattern and TEM image of C/MnO 2 NWs/carbon bers. See

Large-scale uniform α-Co(OH)₂ nanowire arrays (NWAs) with an average length of ∼20 μm grown on pyrolytic graphite (PG) were successfully synthesized by a hydrothermal method at 120 °C. Ultrasonication test was carried out toward the as-made nanoarray products and the result demonstrated their robust adhesion to graphitic substrate. After 300 s of sonication testing, α-Co(OH)₂ NWAs could still possess both integrated one-dimensional (1D) nanoarray architecture and good electronic connections with current collector. When investigated as electrochemical pseudocapacitor electrodes, α-Co(OH)₂ NWAs exhibited good energy-storage performance in terms of high specific capacitance of 642.5 F/g, good rate capability, and excellent capacity retention. Our work not only presents a cost-effective and scale-up synthetic method for α-Co(OH)₂ NWAs but also holds promise in general synthesis of long arrays of other metal hydroxides/oxide (TiO₂, Fe₂O₃, SnO₂, etc.) nanostructures on PG substrate by using α-Co(OH)₂ NWAs as sacrificial templates.

A novel strategy of utilizing supramolecular polymerization for fabricating nitrogen doped porous graphene (NPG) with high doping level of 12 atom% as the anode material for lithium ion batteries is reported for the first time. The introduction of supramolecular polymer (melamine cyanurate) functions not only as a spacer to prevent the restacking of graphene sheets but also as a sacrificial template to generate porous structures, as well as a nitrogen source to induce in situ N doping. Therefore, pores and loose‐packed graphene thin layers with high N doping level are very effectively formed in NPG after the annealing process. Such highly desired structures immediately offer remarkably improved Li storage performance including high reversible capacity (900 mAh g−1 after 150 cycles) with good cycling and rate performances. The effects of annealing temperature and heating rates on the final electrochemical performance of NPG are also investigated. Furthermore, the low cost, facile, and scalable features of this novel strategy may be helpful for the rational design of functionalized graphene‐based materials for diverse applications.

The electrochemical performance of supercapacitors relies not only on the exploitation of high-capacity active materials, but also on the rational design of superior electrode architectures. Herein, a novel supercapacitor electrode comprising 3D hierarchical mixed-oxide nanostructured arrays (NAs) of C/CoNi3 O4 is reported. The network-like C/CoNi3 O4 NAs exhibit a relatively high specific surface area; it is fabricated from ultra-robust Co-Ni hydroxide carbonate precursors through glucose-coating and calcination processes. Thanks to their interconnected three-dimensionally arrayed architecture and mesoporous nature, the C/CoNi3 O4 NA electrode exhibits a large specific capacitance of 1299 F/g and a superior rate performance, demonstrating 78% capacity retention even when the discharge current jumps by 100 times. An optimized asymmetric supercapacitor with the C/CoNi3 O4 NAs as the positive electrode is fabricated. This asymmetric supercapacitor can reversibly cycle at a high potential of 1.8 V, showing excellent cycling durability and also enabling a remarkable power density of ∼13 kW/kg with a high energy density of ∼19.2 W·h/kg. Two such supercapacitors linked in series can simultaneously power four distinct light-emitting diode indicators; they can also drive the motor of remote-controlled model planes. This work not only presents the potential of C/CoNi3 O4 NAs in thin-film supercapacitor applications, but it also demonstrates the superiority of electrodes with such a 3D hierarchical architecture.

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Co-Fe layered double hydroxide (LDH) nanowall arrays (NWAs) have been grown directly from a flexible alloy substrate by a facile hydrothermal method. An ultrasonication test of 30 min towards the as-made Co-Fe LDH NWAs has demonstrated their ultra-robust mechanical adhesion to the substrate. In particular, an in situ carbon-source coating (ISCC) on the Co-Fe LDH NWAs was achieved during their in situ growing process conducted in a glucose-containing reaction solution. After annealing treatment in an argon atmosphere, carbon coated Co-Fe mixed oxide NWAs were evolved from thermal decomposition of LDH precursors and carbonization of glucose, and further investigated as anode materials for lithium-ion batteries (LIBs). When tested, the obtained carbon coated Co-Fe mixed oxide NWAs with improved electrical conductivity exhibited superior electrochemical performance in terms of specific capacity and cyclability as compared to a carbon-free sample and a sample made by the previous carbon-coating method. Our work presents an alternative way to fabricate in situ mixed transition metal oxide nanostructures for high-performance LIBs.