Long Hao

Terephthalonitrile-derived nitrogen-rich networks for high performance supercapacitors

A novel high performance electrode material for supercapacitor applications, terephthalonitrile-derived nitrogen-rich network (TNN), is developed successfully via temperature-dependent cross-linking of terephthalonitrile monomers. This work opens up a new window for seeing a versatile modular toolbox derived from various aromatic nitrile monomers for developing better electrode materials in the future.

Bottom-up construction of triazine-based frameworks as metal-free electrocatalysts for oxygen reduction reaction.

A bottom-up method is used to construct novel metal-free catalysts for deeper study of oxygen reduction reaction (ORR) catalysis. Through controlling the structural evolution of a 2D covalent triazine-based framework, the conductivity, nitrogen configurations, and multidoping structures of the as-prepared catalysts can be easily tuned, which makes a great platform for both studying the mechanisms of the ORR and optimizing the performances of the metal-free catalysts.

Approaching the downsizing limit of silicon for surface-controlled lithium storage.

Graphene-sheet-supported uniform ultrasmall (≈3 nm) silicon quantum dots have been successfully synthesized by a simple and effective self-assembly strategy, exhibiting unprecedented fast, surface-controlled lithium-storage behavior and outstanding lithium-storage properties including extraordinary rate capability and remarkable cycling stability, attributable to the intrinsic role of approaching the downsizing limit of silicon.

Au@MnO2 core-shell nanomesh electrodes for transparent flexible supercapacitors

A novel Au@MnO2 supercapacitor is presented. The sophisticated core-shell architecture combining an Au nanomesh core with a MnO2 shell on a flexible polymeric substrate is demonstrated as an electrode for high performance transparent flexible supercapacitors (TFSCs). Due to their unique structure, high areal/gravimetric capacitance and rate capability for TFSCs are achieved.

A graphene-oxide-based thin coating on the separator: an efficient barrier towards high-stable lithium–sulfur batteries

The electrochemical performance of lithium–sulfur (Li–S) batteries can be significantly improved by simply coating a thin barrier layer on the separator. The spray-coating of a mixture of graphene oxides (GO) and oxidized carbon nanotubes (o-CNT) can achieve a barrier coating of only 0.3 mg cm−2, which is much less than conventional interlayers and has no negative impact on the energy density but significantly enhances the electrochemical performances of the whole battery device. Due to the binding forces induced by functional groups on GO and the interconnected nanoscale channels provided by o-CNT, the thus fabricated Li–S batteries show dramatically improved specific discharge capacities of up to 750 mAh g−1 at 1 C even after 100 cycles, more than twice those of batteries without barrier coatings.

Graphenal Polymers for Energy Storage

A key to improve the electrochemical performance of energy storage systems (e.g., lithium ion batteries and supercapacitors) is to develop advanced electrode materials. In the last few years, although originating from the unique structure and property of graphene, interest has expanded beyond the originally literally defined graphene into versatile integration of numerous intermediate structures lying between graphene and organic polymer, particularly for the development of new electrode materials for energy storage devices. Notably, diverse designations have shaded common characteristics of the molecular configurations of these newly-emerging materials, severely impeding the design, synthesis, tailoring, functionalization, and control of functional electrode materials in a rational and systematical manner. This concept paper highlights all these intermediate materials, specifically comprising graphene subunits intrinsically interconnected by organic linkers or fractions, following a general concept of graphenal polymers. Combined with recent advances made by our group and others, two representative synthesis approaches (bottom-up and top-down) for graphenal polymers are outlined, as well as the structure-property relationships of these graphenal polymers as energy storage electrode materials are discussed.

A Facile Reduction Method for Roll‐to‐Roll Production of High Performance Graphene‐Based Transparent Conductive Films

A facile roll-to-roll method is developed for fabricating reduced graphene oxide (rGO)-based flexible transparent conductive films. A Sn2+ /ethanol reduction system and a rationally designed fast coating-drying-washing technique are proven to be highly efficient for low-cost continuous production of large-area rGO films and patterned rGO films, extremely beneficial toward the manufacture of flexible photoelectronic devices.

Graphene-templated formation of 3D tin-based foams for lithium ion storage applications with a long lifespan

3D tin-based foams with tailorable pore structures are developed through a graphene-templated freeze-drying approach. Pore structure effects on the electrochemical properties of the G/SnO2@C composite foam are investigated. Further the carbon coating endows the foam-like nanocomposite with superior cycling stability and rate capability.

Synergistically engineered self-standing silicon/carbon composite arrays as high performance lithium battery anodes

The synergistically engineered self-standing silicon/carbon composite arrays exhibit unprecedented lithium storage performance, including a high specific capacity of 1510 mA h g−1 based on the total electrode weight, extraordinary cycling stability with nearly 100% capacity retention over 600 cycles, and areal capacity approaching the value of commercial lithium-ion batteries (3.9 mA h cm−2).

A fast room-temperature strategy for direct reduction of graphene oxide films towards flexible transparent conductive films

Chemically reduced graphene oxide (rGO) is widely studied as a transparent electrode, as it can be cheaply prepared on a large scale, easily integrated into flexible devices, and contributes to excellent device performances. However, the commonly used reduction methods for converting graphene oxide (GO) films into rGO ones generally involve toxic reagents or complex transfer steps. In this report, we develop a simple short-term room-temperature strategy for the direct fabrication of rGO-based transparent conductive films on flexible substrates, where tin (Sn) is used to promote the conversion of pre-deposited GO films into rGO ones. The thus-prepared rGO films exhibit sheet resistances of 6.7–17.3 kΩ sq−1 and transparencies of 75–81% at 550 nm, indicating great potential of the here-developed methodology for the fabrication of graphene-based transparent conductive films, under conditions without any heating and transferring processes, as well as toxic agents.