홍성현 교수

Abstract Ni‐rich layered LiNi x Co y Mn 1− x − y O 2 (LNCM) with Ni content over >90% is considered as a promising lithium ion battery (LIB) cathode, attributed by its low cost and high practical capacity. However, Ni‐rich LNCM inevitably suffers rapid capacity fading at a high state of charge due to the mechanochemical breakdown; in particular, the microcrack formation has been regarded as one of the main culprits for Ni‐rich layered cathode failure. To address these issues, Ni‐rich layered

Textured Nb‐doped bismuth titanate ceramics (Bi 4 Ti 3− x /5 ‐ Nb x /5 O 12 , where x = 0.02) were fabricated by templated grain growth. It was found that the use of a fine precursor powder led to enhanced densification of the ceramic, while Nb doping reduced electrical conduction and dielectric loss, which enabled poling at high temperatures and high electric fields. Sintered tapes showed anisotropic dielectric and piezoelectric properties when measured parallel and perpendicular to the casting

The silicon nanostructure is a promising candidate for an anode of Li-ion batteries due to its high theoretical capacity. In this work, we have demonstrated the scalable synthesis of Si nanosheets from natural sand by magnesiothermic reduction, and suggested a new formation mechanism for Si nanosheets. In the suggested mechanism, an Mg₂Si intermediate phase was formed at an early stage of the reduction process, which leads to the two-dimensional Si nanostructure. The synthesized Si nanosheets ha

Silver (or platinum)-containing calcium phosphate (hydroxyapatite (HA) and tricalcium phosphate (alpha-TCP)) coatings on titanium substrates were formed by micro-arc oxidation (MAO) and their in vitro antibacterial activity and in vitro cytotoxicity were evaluated. MAO was performed in an electrolytic solution containing beta-glycerophosphate disodium salt pentahydrate (beta-GP) and calcium acetate monohydrate (CA), and Ag and Pt were introduced in the form of AgNO(3) (or CH(3)COOAg) and H(2)PtC

SnO2@TiO2 double-shell nanotubes have been facilely synthesized by atomic layer deposition (ALD) using electrospun PAN nanofibers as templates. The double-shell nanotubes exhibited excellent high rate cyclability for lithium ion batteries. The retention of hollow structures during cycling was demonstrated.

Silicon (Si) is considered to be one of the most promising anode candidates for next-generation lithium-ion batteries because of its high theoretical specific capacity and low discharge potential. However, its poor cyclability, caused by tremendous volume change during cycling, prevents commercial use of the Si anode. Herein, we demonstrate a high-performance Si anode produced via covalent bond formation between a commercially available Si nanopowder and a linear polymeric binder through an este

Densification and anisotropic grain growth in diphasic‐gel‐derived, titania‐doped mullite were studied. Titania enhanced initial and intermediate stage densification in diphasic mullite gels by reducing the glass viscosity. Rodlike anisotropic mullite grains started to grow in titania‐doped diphasic mullite gels once a dense, equiaxed microstructure was achieved. The onset temperature for anisotropic grain growth decreased with increasing titania concentration because the sintering temperature f

Solid electrolytes, LiTi 2 (PO 4 ) 3 (LTP), Li 1.3 Al 0.3 Ti 1.7 (PO 4 ) 3 (LATP), and Li 1.3 Al 0.3 Ti 1.7 (PO 4 ) 2.9 (VO 4 ) 0.1 (LATPV), were prepared by conventional sintering (CS) and spark plasma sintering (SPS) methods, and the Li + ion conductivity of the sintered pellets was examined using an impedance analyzer. SPS remarkably improved the densification compared to CS and resulted in dense ceramics (95–97% of theoretical density) irrespective of the substituted ions. The highest conduc

The suppression of oxygen oxidation is proposed as the critical origin of Zr doping on LiNi 0.92 Co 0.04 Mn 0.04 O 2 layered oxide LIB cathode material.