Jicai Liang

Mechanical properties and crystallization behavior of poly(butylene succinate) composites reinforced with basalt fiber

Biodegradable poly(butylene succinate) (PBS)/basalt fiber (BF) composites were prepared by melt blending method using twin-screw extruder followed by injection molding. Mechanical properties, crystallization and melting behavior, morphology, crystal structure and thermal stability of PBS/BF composites with various BF contents were investigated by different techniques. The tensile and impact properties of the composites were improved markedly with the addition of BF, due to the efficient interfacial adhesion between fibers and PBS matrix. Crystallization and melting behavior of PBS in its composites kept almost unchanged, indicating that the nucleation effect of BF was minimal and, meanwhile, it played a role in hindrance of chain motion. TG analysis showed that the thermal stability of PBS/BF composites was enhanced by the addition of BF. The crystal structure of PBS was not affected by the incorporation of BF, while the nucleation density increased gradually and the spherulite size reduced remarkably with the increase in BF. No transcrystallization phenomenon on the surface of BF was observed maybe as a result of without surface treatment.

Cobalt nanoparticles encapsulated in N-doped graphene nanoshells as an efficient cathode electrocatalyst for a mechanical rechargeable zinc–air battery

Air-cathodes with properties of efficiency, durability and low cost are essential for high performance metal–air batteries and fuel cells for practical applications. In this study, non-precious metal ORR electrocatalysts derived by the encapsulation of Co nanoparticles in N-doped graphene nanoshells were synthesized by a typical one-step pyrolysis process. Compared with commercial Pt/C catalysts, the prepared Co-30@N-G hybrid electrocatalyst showed a high ORR activity at the same level in an alkaline medium. Subsequently, the Co-30@N-G hybrid electrocatalyst has been used as a cathode of Zn–air batteries, which displays equivalent performance to the systems derived using a commercial Pt/C catalyst. The Co-30@N-G derived mechanical rechargeable Zn–air battery showed a persistent flat discharge curve with minimum voltage loss at a high discharge rate of 40 mA cm−2. The robustness of the Co-30@N-G ORR catalyst can allow the batteries to work constantly by periodically replacing the Zn anode and electrolyte, presenting an efficient and economical cathode for Zn–air flow batteries or Zn–air fuel cells.

TiO2 hollow spheres on reduced graphene oxide with high rate performance as anodes for lithium-ion batteries

Anatase TiO2 anchored on graphene oxide (GO) can be synthesized through a one-step hydrothermal method. The as-formed nanohybrid has a unique hollow structure and a large surface area. More importantly, compared to the pristine TiO2 counterpart, TiO2@RGO composite materials as anodes in lithium-ion batteries have demonstrated a uniform and highly crystallized morphology and exhibited excellent cycling stability and rate capability of 352xa0mA h g−1 at 0.5C and 223 mA h g−1 at 5C after 100 cycles, indicating that the TiO2@RGO nanocomposite has promise in advanced Li-ion batteries. The improvement of electrochemical performance is assigned to the enhanced conductivity in the presence of GO in the TiO2@RGO nanocomposite, the anatase and TiO2–B mixed crystal phase of the hollow sphere TiO2@RGO nanocomposite, the small size of TiO2 particles in the nanocomposite, and the enlarged electrode/electrolyte contact area, leading to more active sites in TiO2@RGO.

In-situ synthesis of hierarchical Mn-decorated NiCo 2 S 4 nanosheet arrays on Ni foam as binder-free electrodes for high-performance supercapacitors

In this paper, novel hierarchical Mn-decorated NiCo2S4 nanosheet arrays on Ni foam have been synthesized by a facile multi-step hydrothermal method and directly used as binder-free electrodes for supercapacitors. The vertically aligned NiCo2S4 nanosheet arrays on Ni foam act as not only a good pseudocapacitive material but also a conductive scaffold that can be uniformly decorated by ultrathin and interconnected chiffon-like nanoflakes of MnS2. This unique architecture with a highly specific surface area and fast transfer channels for electron and ion can employ many independent nanospaces to participate in electrochemical reaction. The optimized Mn-decorated NiCo2S4 nanosheet arrays electrode represents an impressive areal capacitance of 4.6xa0Fxa0cm−2 at 2xa0mAxa0cm−2 and good cycling stability (87.3% of the areal capacitance can be maintained after 2000 cycles at 10xa0mAxa0cm−2), indicating the great potential of this hybrid hierarchical nanostructure as a promising candidate for high-performance supercapacitors.

CoSb3 alloy nanoparticles wrapped with N-doped carbon layers as a highly active bifunctional electrocatalyst for zinc–air batteries

Rational design and successful synthesis of highly efficient, long-term stable and low-cost bifunctional electro-catalysts are vital for commercialized application of rechargeable zinc–air batteries. Herein, a series of composite catalysts of different contents of CoSb3 alloy nanoparticles wrapped with N-doped carbon layers (CoSb3@NCL) have been synthesized by a simple one-step pyrolytic process. The optimized catalyst (CoSb3@NCL-30) exhibits excellent catalytic activities for both the ORR and OER in alkaline medium, which can be competitive with the Pt/C catalyst (20%). More importantly, a real rechargeable zinc–air battery with the CoSb3@NCL-30 catalyst serving as an air cathode exhibits outstanding electrochemical properties and excellent cycling stability (the overall increment of the voltage gap was only 0.1 V after 60 hours), making it possible to replace expensive noble metal-based catalysts for actual application in rechargeable zinc–air batteries.

Embedding FeSb alloy nanoparticles in N-doped carbon layers as an efficient bifunctional electrocatalyst for zinc-air battery

Due to the intrinsic sluggish kinetics of oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), developing highly efficient and inexpensive bifunctional electrocatalysts are crucial for high-performance zinc-air battery. In this paper, a series of hybrid electrocatalysts by embedding FeSb alloy nanoparticles in nitrogen-doped carbon layers (FeSb-N-CLs) have been prepared by a facile pyrolysis of solid-phase precursor. The optimized FeSb-N-CLs-50 cathode catalyst exhibits excellent activity and stability to the ORR and OER in alkaline medium, which can be competitive with commercial Pt/C catalyst (20%). More importantly, the good performance and high stability of the primary and rechargeable zinc-air batteries employing FeSb-N-CLs-50 as cathodes further demonstrate this hybrid catalyst is a favorable and promising candidate to replace noble metal-based catalysts for the application in zinc-air batteries.

Research on the Cross Section Forming Quality of Three-Dimensional Multipoint Stretch Forming Parts

This paper introduced the basic principle and main influencing factors of the three-dimensional multipoint stretch forming process and investigated the optimized scheme of the cross section forming quality. The main factors affecting the stretch forming process were studied by the orthogonal test through the numerical simulation technique. In the case of a good target shape, the best combination of forming parameters was established by using the range method. The cross-sectional distortion of the formed profile is the smallest when the prestretching amount is 1% of the profile length, the poststretching amount is 0.8% of the profile length, the number of the die heads is 12, and the friction coefficient is 0.15. The optimal combination of forming parameters was verified by the multipoint bending test.

Effect of Flexible 3D Multipoint Stretch Bending Dies on the Shape Accuracy and the Optimal Design

Aiming at the flexible 3D stretch bending with multipoint dies for the aluminum profile, the numerical simulation analysis of the bending process was carried out by ABAQUS finite element software. In the multipoint stretch bending (MPSB) process, the influence of the number of die units on the springback for the complex section profile was studied. The shape error between the forming parts and the target parts was reduced through the method of die surface modification. The results showed that the springback of the aluminum profile could reach a minimum when the number of die units was 25 under the precondition of saving cost and ensuring the quality of forming parts. In the numerical simulation, the maximum shape error of the forming parts reduced from 18.824u2009mm to 2.456u2009mm; in the test, the maximum shape error reduced from 27.26u2009mm to 6.03u2009mm through the method of die surface modification.