Sunjin Kim

Mussel‐Inspired Adhesive Binders for High‐Performance Silicon Nanoparticle Anodes in Lithium‐Ion Batteries

Conjugation of mussel-inspired catechol groups to various polymer backbones results in materials suitable as silicon anode binders. The unique wetness-resistant adhesion provided by the catechol groups allows the silicon nanoparticle electrodes to maintain their structure throughout the repeated volume expansion and shrinkage during lithiation cycling, thus facilitating substantially improved specific capacities and cycle lives of lithium-ion batteries.

Comparative study of physical methods for lipid oxidation measurement in oils

For the determination of lipid oxidation in oils, electrical, optical, spectroscopic and extraction methods were investigated using rice bran oil and doubly-fractionated palm olein as model systems. The oxidized polar components and dielectric constant of rice bran oil increased very similarly with those of double-fractionated palm olein. In the case of rice bran oil, all of the test methods were shown to possess good statistical correlations. Polar components, dielectric constant, refractive index and polymer content showed relatively better correlations. It was shown that diene and triene content determined by spectroscopic methods was not suitable for more saturated oils such as palm olein.

Nanomechanics of Poly(catecholamine) Coatings in Aqueous Solutions

Mussel-inspired self-polymerized catecholamine coatings have been widely utilized as a versatile coating strategy that can be applied to a variety of substrates. For the first time, nanomechanical measurements and an evaluation of the contribution of primary amine groups to poly(catecholamine) coatings have been conducted using a surface-forces apparatus. The adhesive strength between the poly(catecholamine) layers is 30-times higher than that of a poly(catechol) coating. The origin of the strong attraction between the poly(catecholamine) layers is probably due to surface salt displacement by the primary amine, π-π stacking (the quadrupole-quadrupole interaction of indolic crosslinks), and cation-π interactions (the monopole-quadrupole interaction between positively charged amine groups and the indolic crosslinks). The contribution of the primary amine group to the catecholamine coating is vital for the design and development of mussel-inspired catechol-based coating materials.

A “Sticky” Mucin‐Inspired DNA‐Polysaccharide Binder for Silicon and Silicon–Graphite Blended Anodes in Lithium‐Ion Batteries

New binder concepts have lately demonstrated improvements in the cycle life of high-capacity silicon anodes. Those binder designs adopt adhesive functional groups to enhance affinity with silicon particles and 3D network conformation to secure electrode integrity. However, homogeneous distribution of silicon particles in the presence of a substantial volumetric content of carbonaceous components (i.e., conductive agent, graphite, etc.) is still difficult to achieve while the binder maintains its desired 3D network. Inspired by mucin, the amphiphilic macromolecular lubricant, secreted on the hydrophobic surface of gastrointestine to interface aqueous serous fluid, here, a renatured DNA-alginate amphiphilic binder for silicon and silicon-graphite blended electrodes is reported. Mimicking mucins structure comprised of a hydrophobic protein backbone and hydrophilic oligosaccharide branches, the renatured DNA-alginate binder offers amphiphilicity from both components, along with a 3D fractal network structure. The DNA-alginate binder facilitates homogeneous distribution of electrode components in the electrode as well as its enhanced adhesion onto a current collector, leading to improved cyclability in both silicon and silicon-graphite blended electrodes.

Epitaxial growth of magnetic nanowires by chemical vapor transport

This chapter provides some background on the epitaxial growth of various nanowires (NWs) with interesting magnetic properties that have been developed using a simple and robust chemical vapor transport (CVT) technique. To epitaxially grow single-crystalline magnetic NWs, a suitable single-crystalline substrate should be used, and the reaction conditions need to be specifically optimized. This chapter discusses the diffusion-driven crystal structure transformation method after a CVT reaction, as well as a direct one-step CVT reaction, as synthetic approaches to obtaining epitaxial arrays of transition metal and transition metal-containing compound NWs. Such epitaxially grown magnetic NWs can be used as advanced building blocks for a wide range of spintronic applications.