Xiangyan Shen

Hydrogen substituted graphdiyne as carbon-rich flexible electrode for lithium and sodium ion batteries

Organic electrodes are potential alternatives to current inorganic electrode materials for lithium ion and sodium ion batteries powering portable and wearable electronics, in terms of their mechanical flexibility, function tunability and low cost. However, the low capacity, poor rate performance and rapid capacity degradation impede their practical application. Here, we concentrate on the molecular design for improved conductivity and capacity, and favorable bulk ion transport. Through an in situ cross-coupling reaction of triethynylbenzene on copper foil, the carbon-rich frame hydrogen substituted graphdiyne film is fabricated. The organic film can act as free-standing flexible electrode for both lithium ion and sodium ion batteries, and large reversible capacities of 1050u2009mAhu2009g−1 for lithium ion batteries and 650u2009mAhu2009g−1 for sodium ion batteries are achieved. The electrode also shows a superior rate and cycle performances owing to the extended π-conjugated system, and the hierarchical pore bulk with large surface area.Flexible batteries have been used to power wearable smart electronics and implantable medical devices. Here, the authors report a carbon-rich flexible hydrogen substituted graphdiyne electrode exhibiting superior electrochemical performance in lithium and sodium ion batteries.

Preparation of 3D Architecture Graphdiyne Nanosheets for High-Performance Sodium-Ion Batteries and Capacitors

Here, we apply three-dimensional (3D) architecture graphdiyne nanosheet (GDY-NS) as anode materials for sodium-ion storage devices achieving high energy and power performance along with excellent cyclic ability. The contribution of 3D architecture nanostructure and intramolecular pores of the GDY-NS can substantially optimize the sodium storage behavior through the accommodated intramolecular pore, 3D interconnective porous structure, and increased activity sites to facilitate a fast sodium-ion-diffusion channel. The contribution of butadiyne linkages and the formation of a stable solid electrolyte interface layer are directly confirmed through the in situ Raman measurement. The GDY-NS-based sodium-ion batteries exhibit a stable reversible capacity of approximately 812 mAh g-1 at a current density of 0.05 A g-1; they maintain more than 405 mAh g-1 over 1000 cycles at a current density of 1 A g-1. Furthermore, the sodium-ion capacitors could deliver a capacitance more than 200 F g-1 over 3000 cycles at 1 A g-1 and display an initial specific energy as high as 182.3 Wh kg-1 at a power density of 300 W kg-1 and maintain specific energy of 166 Wh kg-1 even at a power density of 15u2009000 W kg-1. The high energy and power density along with excellent cyclic performance based on the GDY-NS anode offers a great potential toward application on next-generation energy storage devices.

Construction of Large-Area Uniform Graphdiyne Film for High-Performance Lithium-Ion Batteries

Large-area graphdiyne film is constructed by heat treatment, including thermally induced evaporation and a cross-coupling reaction process. The growth mechanism is proposed based on the observation and characterization that the heating temperature plays an important role in the evaporation of oligomers and in triggering the thermal cross-coupling reaction, whereas the heating duration mainly determines the execution of the thermal cross-coupling reaction. By controlling the heat-treatment process, a graphdiyne film with uniform morphology and good conductivity is obtained. The improved GDY film based electrodes deliver good interfacial contact and more lithium storage sites; thus leading to superior electrochemical performance. A reversible capacity of 901u2005mAhu2009g-1 is achieved. Specifically, the electrodes exhibit excellent rate performance, with which a capacity of 430u2005mAhu2009g-1 is maintained at a rate as high as 5u2005Au2009g-1 . These advantages mean that the uniform graphdiyne film is a good candidate for the fabrication of a flexible and high-capacity electrode material.

Graphdiyne Containing Atomically Precise N Atoms for Efficient Anchoring of Lithium Ion

The qualitative and quantitative nitrogen-doping strategy for carbon materials is reported here. Novel porous nanocarbon networks pyrimidine-graphdiyne (PM-GDY) and pyridine-graphdiyne (PY-GDY) films with large areas were successfully prepared. These films are self-supported, uniform, continuous, flexible, transparent, and quantitively doped with merely pyridine-like nitrogen (N) atoms through the facile chemical synthesis route. Theoretical predictions imply these N doped carbonaceous materials are much favorable for storing lithium (Li)-ions since the pyridinic N can enhance the interrelated binding energy. As predicted, PY-GDY and PM-GDY display excellent electrochemical performance as anode materials of LIBs, such as the superior rate capability, the high capacity of 1168 (1165) mA h g-1 at current density of 100 mA g-1 for PY-GDY (PM-GDY), and the excellent stability of cycling for 1500 (4000) cycles at 5000 mA g-1 for PY-GDY (PM-GDY).

Fluoride graphdiyne as a free-standing electrode displaying ultra-stable and extraordinary high Li storage performance

In natural two-dimensional (2D) materials (such as graphene, transition metal dichalcogenides and transition metal carbides), energy and power density are inevitably hindered by Li ion diffusion perpendicular to the compact atomic layer. At the same time, their cycling stability is affected by side reactions due to the large specific surface area and high activity of surface atoms. Here we report the preparation of a new 2D carbon rich framework called fluoride graphdiyne (F-GDY). The experiments, together with theoretical calculations, show that extraordinarily high reversible capacity (1700 mA h g−1) and extremely stable cycle performance (9000 cycles) are achieved by the reversible transition between C–F semi-ionic bonds and ionic bonds at the plateaus of 0.9 V. This bottom-up strategy offers a versatile approach to the rational design of ultra-stable flexible 2D materials through solution-based processability for application in the efficient electrodes of high performance rechargeable batteries.