Ocean University of China

About: Ocean University of China is a education organization based out in Qingdao, China. It is known for research contribution in the topics: Population & Sea surface temperature. The organization has 27604 authors who have published 27886 publications receiving 440181 citations. The organization is also known as: Zhōngguó Hǎiyáng Dàxué & OUC.

Electrically insulating thermal nano-oils using 2D fillers.

Abstract: Different nanoscale fillers have been used to create composite fluids for applications such as thermal management. The ever increasing thermal loads in applications now require advanced operational fluids, for example, high thermal conductivity dielectric oils in transformers. These oils require excellent filler dispersion, high thermal conduction, but also electrical insulation. Such thermal oils that conform to this thermal/electrical requirement, and yet remain in highly suspended stable state, have not yet been synthesized. We report here the synthesis and characterization of stable high thermal conductivity Newtonian nanofluids using exfoliated layers of hexagonal boron nitride in oil without compromising its electrically insulating property. Two-dimensional nanosheets of hexagonal boron nitride are liquid exfoliated in isopropyl alcohol and redispersed in mineral oil, used as standard transformer oil, forming stable nanosuspensions with high shelf life. A high electrical resistivity, even higher than that of the base oil, is maintained for the nano-oil containing small weight fraction of the filler (0.01 wt %), whereas the thermal conductivity was enhanced. The low dissipation factor and high pour point for this nano-oil suggests several applications in thermal management.

N, O-codoped hierarchical porous carbons derived from algae for high-capacity supercapacitors and battery anodes

Abstract: Nitrogen and oxygen codoped hierarchical porous carbons have been synthesized by using a direct carbonization/activation procedure of biomass algae – Enteromorpha. The proposed procedure allowed us to produce carbons with high surface area (up to 2073 m2 g−1), sponge-like 3D interconnected structure, combined macro/meso/micropores, and rich N (0.64–0.85 at%) and O (11.36–12.24 at%) doping. The application of the produced carbons in supercapacitors based on an ionic liquid electrolyte showed a high specific capacitance of 201 F g−1 (10.7 μF cm−2) at 1 A g−1 and 20 °C, a capacitance retention ratio of 61% at 100 A g−1 and a capacitance loss of 9% after 10 000 cycles. The devices were able to deliver an energy density of 24 or 35 W h kg−1 (on an active mass normalized basis) at an extremely high power density of 60 kW kg−1 at 20 or 60 °C. The application of the produced carbons in a lithium-ion battery anode based on the LiPF6 electrolyte exhibited a high specific capacity of 1347–1709 mA h g−1, a good initial coulombic efficiency of 61–64%, and a good cyclability up to 500 cycles. We believe that this simple precursor-synthesis route offers excellent potential for facile large-scale material production for supercapacitors and lithium ion batteries.