Homogeneous Deposition of Zinc on N-Doped Carbon Fibers Interconnected with Sn Nanoparticles for Advanced Aqueous Zinc Batteries.

Currently, inhomogeneous distribution of Zn2+ on the surface of the Zn anode is still the essential reason for dendrite formation and unsatisfactory stability of zinc ion batteries. Given the merits of strong interaction between Sn and Zn, as well as a low nucleation barrier during Zn deposition, the combination of metallic Sn with carbon material is expected to improve the deposition of zinc ions and inhibit the growth of zinc dendrites by guiding the homogeneous plating/stripping of zinc on the electrode surface. In this article, zincophilic Sn nanoparticles with low nucleation barriers and strong interaction with Zn2+ were embedded into 3D N-doped carbon nanofibers using a simple electrostatic spinning technique. Accordingly, when serving as an artificial coating layer for the zinc metal anode, an ultrastable Sn@NCNFs@Zn||Sn@NCNFs@Zn symmetric cell can be achieved for over 3500 h with a low nucleation overpotential of 29.1 mV. Significantly, the full cell device assembled with the as-prepared anode and MnO2 cathode exhibits desirable electrochemical behaviors. Moreover, this simple method could be extended to other metal-carbon composites, and to ensure ease in scaling up as required. Such significant approach can provide an effective strategy for the design of high-performance zinc anodes.

Construction and Electrochemical Properties of Solid-state Supercapacitors with Redox Additives.

Adding redox additives to conventional electrolytes is considered to be an effective method to improve electrochemical performance of the supercapacitors, which is ascribed to the additional Farady capacitance derived from the reversible redox reaction. Here, the influence of K3 Fe(CN)6 on electrochemical properties for single electrode system and the assembled solid-state supercapacitor are investigated. The carbon felt (CF) electrode in the mixed solution of K3 Fe(CN)6 /KCl exhibits remarkable specific capacitance of 2.45 F cm-2 after 5000 cycles, obviously much higher than conventional electrolyte KCl. The capacitance retention and the coulombic efficiency of the solid-state supercapacitor maintains 86.5% and 97% after 2500 cycles, symmetric supercapacitor shows a high energy density of 58 mWh L-1 at power density of 660 mW L-1 . Furthermore, the solid-state SCs exhibit excellent flexibility and four supercapacitors are capable of lighting up an LED lamp, demonstrating the potential of practical applications of the as-prepared solid-state SCs.

Fabrication of Titanium and Copper-Coated Diamond/Copper Composites via Selective Laser Melting.

The poor wettability and weak interfacial bonding of diamond/copper composites are due to the incompatibility between diamond and copper which are inorganic nonmetallic and metallic material, respectively, which limit their further application in next-generation heat management materials. Coating copper and titanium on the diamond particle surface could effectively modify and improve the wettability of the diamond/copper interface via electroless plating and evaporation methods, respectively. Here, these dense and complex composites were successfully three-dimensionally printed via selective laser melting. A high thermal conductivity (TC, 336 W/mK) was produced by 3D printing 1 vol.% copper-coated diamond/copper mixed powders at an energy density of 300 J/mm3 (laser power = 180 W and scanning rate = 200 mm/s). 1 and 3 vol.% copper-coated diamond/copper composites had lower coefficients of thermal expansions and higher TCs. They also had stronger bending strengths than the corresponding titanium-coated diamond/copper composites. The interface between copper matrix and diamond reinforcement was well bonded, and there was no cracking in the 1 vol.% copper-coated diamond/copper composite sample. The optimization of the printing parameters and strategy herein is beneficial to develop new approaches for the further construction of a wider range of micro-sized diamond particles reinforced metal matrix composites.