Surface Oxygen Vacancy Inducing Li-Ion-Conducting Percolation Network in Composite Solid Electrolytes for All-Solid-State Lithium-Metal Batteries.

Composite solid electrolytes (CSEs) are newly emerging components for all-solid-state Li-metal batteries owing to their excellent processability and compatibility with the electrodes. Moreover, the ionic conductivity of the CSEs is one order of magnitude higher than the solid polymer electrolytes (SPEs) by incorporation of inorganic fillers into SPEs. However, their advancement has come to a standstill owing to unclear Li-ion conduction mechanism and pathway. Herein, the dominating effect of the oxygen vacancy (Ovac ) in the inorganic filler on the ionic conductivity of CSEs is demonstrated via Li-ion-conducting percolation network model. Based on density functional theory, indium tin oxide nanoparticles (ITO NPs) are selected as inorganic filler to determine the effect of Ovac on the ionic conductivity of the CSEs. Owing to the fast Li-ion conduction through the Ovac inducing percolation network on ITO NP-polymer interface, LiFePO4 /CSE/Li cells using CSEs exhibit a remarkable capacity in long-term cycling (154 mAh g-1 at 0.5C after 700 cycles). Moreover, by modifying the Ovac concentration of ITO NPs via UV-ozone oxygen-vacancy modification, the ionic conductivity dependence of the CSEs on the surface Ovac from the inorganic filler is directly verified.

Fabrication of Water Soluble Polymer Capsules for Protecting Mineral Admixtures in Groundwater for Emergency Recovery of Sinkhole.

Polyethylene glycol (PEG) based water-soluble polymer composites were fabricated for mineral admixture encapsulants to be used in underground sinkhole restoration. Linear low-density polyethylene (LLDPE) and talc were added to the composites to increase their mechanical strengths and heat resistances. PEG/LLDPE/Talc composites were manufactured via melt mixing using a twin extruder. Blending PEG and LLDPE increased the mechanical properties and heat resistances of the composite, but decreased the water solubility. Talc was added to the composite to increase mechanical properties and heat resistance. The addition of talc increased the water solubilities of PEG-based composites. The highest tensile strength and impact strength were 2.89 MPa and 2.86, respectively, the increase rate being 9.63-fold relative to that of pristine PEG.

Ionic Liquid Electrolytes for Electrochemical Energy Storage Devices.

For decades, improvements in electrolytes and electrodes have driven the development of electrochemical energy storage devices. Generally, electrodes and electrolytes should not be developed separately due to the importance of the interaction at their interface. The energy storage ability and safety of energy storage devices are in fact determined by the arrangement of ions and electrons between the electrode and the electrolyte. In this paper, the physicochemical and electrochemical properties of lithium-ion batteries and supercapacitors using ionic liquids (ILs) as an electrolyte are reviewed. Additionally, the energy storage device ILs developed over the last decade are introduced.

Facile Liquid-Exfoliation Process of Boron Nitride Nanosheets for Thermal Conductive Polyphthalamide Composite.

In this study, we describe the fabrication of thermally conductive composites based on a polyphthalamide (PPA) matrix by the exfoliation of hexagonal BN nanosheets (BNNs) via the melt-mixing method. Boron nitride (BN) particles were hydroxyl groups surface-treated with sodium hydroxide (NaOH). Compared with existing BN peeling experiments, we successfully produced BNNs that are simpler, more economical, and have an excellent aspect ratio. For the same weight content of BN and BNNs, PPA/BN composites surface-treated with high aspect ratio BNNs have a high in-plane and through-plane thermal conductivity because of the intercalation of the hydroxyl group surface treatments between BN and PPA, which not only increases the wettability but also provides a good heat transfer path. Moreover, wide and thin BNNs are evenly dispersed inside the PPA/BN composite to provide excellent heat transfer paths in both in-plane and through-plane directions.

MnCo2O4 nanoparticles supported on nitrogen and sulfur co-doped mesoporous carbon spheres as efficient electrocatalysts for oxygen catalytic reactions.

The development of efficient bifunctional electrocatalysts for the oxygen reduction and oxygen evolution reactions is essential to address the challenge of sluggish reaction kinetics. MnCo2O4 nanoparticles supported on nitrogen and sulfur co-doped mesoporous carbon spheres are prepared as non-precious metal electrocatalysts by pyrolysis of thiourea and hydrothermal treatment. The co-doping of nitrogen and sulfur from thiourea into the carbon spheres plays an important role in bimetallic covalent coupling with manganese and cobalt oxides. The as-prepared catalysts exhibit promising catalytic performance of the oxygen reduction reaction compared to commercial platinum catalysts due to the existence of highly active sites. Remarkably, the as-prepared catalysts also exhibit promising catalytic activity of the oxygen evolution reaction, comparable to that of commercial ruthenium oxide in terms of the onset potentials and Tafel slope, and show better durability for both the oxygen reduction reaction and oxygen evolution reaction in an alkaline solution.

Surface modification of a BN/ETDS composite with aniline trimer for high thermal conductivity and excellent mechanical properties.

Boron nitride (BN) particles surface-treated with different amounts of aniline trimer (AT) were used to prepare thermally conductive polymer composites with epoxy-terminated dimethylsiloxane (ETDS). For the same weight content of BN, the BN composites surface-treated with AT showed better mechanical strength and thermal conductivity than the pure BN composites. This is because of the intercalation of AT between BN and ETDS, which not only increased the wettability but also provided excellent heat transfer pathways. We determined the optimum surface treatment ratio by varying the amount of AT, and the results are discussed regarding the thermal conductivity, storage modulus, and tensile strength. Finally, we established the optimum AT ratio for BN surface treatment.

Laser direct structuring and electroless plating applicable super-engineering plastic PPS based thermal conductive composite with particle surface modification.

Boron nitride (BN) and laser activate particles (LAPs) were surface-modified via base treatment and by using a silane coupling agent in order to confer functionality and enhance the interfacial affinity of these particles for a polymer matrix. The introduction of LAP and BN caused severe deterioration of the mechanical properties of the filler-polymer composite by acting as defects and due to the poor interface with polyphenylene sulfide (PPS), used as the polymeric matrix. As expected, the thermal and mechanical properties were enhanced via surface modification, whereas the tensile strength of the composites with the surface-modified fillers remained lower than that of neat PPS. The BN/LAP binary filler system showed little influence on the mechanical properties of the composite. However, the incorporation of a small amount of LAP into the BN composite produced a slight improvement of the thermal conductivity when the total filler content was maintained. Moreover, LAP leads the metal plating at the laser irradiated surface. Thus, the BN/LAP/PPS composite was used to fabricate a circuit board via laser direct structuring (LDS) and electroless plating for potential light emitting diode (LED) application.