研究成果/Research Reports

-COVID-19 Issue-

The setup of an automatic atmospheric pressure plasma system for odor removal on medical facial masks 

-Engineering Materials: Plasma Nitriding/Hardening-

Atmospheric pressure plasma hardening for the resistances of wear and impact  

-Energy Materials: Vanadium Redox Flow Batteries-

Eco-Friendly Modification of VRFB Electrodes: Atmospheric Pressure Plasma Jet-Deposited Metal Oxides on Graphite Felt

-Energy Materials: Solid Oxide Fuel Cells-

Amid growing awareness of the global energy crisis, developing technologies to transition away from petroleum-based energy is essential.  Mid-to-low temperature solid oxide fuel cells depend on the ionic conductivity of the electrolyte and the oxygen-reduction performance of the cathode. The applicant focuses on developing high-density, high-ionic-conductivity electrolyte coatings and porous-structure cathode coatings, using materials such as LSM, LSCF, silver, and zirconia. The laboratory's atmospheric plasma jet process combines spray pyrolysis with plasma-assisted chemical vapor deposition effects to enable efficient reactions. This process has advantages such as not requiring expensive equipment, using low-cost non-toxic precursors, and rapid deposition, making it a novel green coating technology. 

Journal Papers: Ag, GDC, La0.5Sr0.5MnO3, Ag/Cu/Ni,  Oxygen vacancies stabilized tetragonal ZrO2, Tetragonal ZrO2

-Energy Materials: Lithium-ion Batteries-

The significant contributions of atmospheric pressure plasma jet (APPJ) technology in enhancing the performance of lithium-ion batteries (LIBs) used in electric vehicles (EVs). APPJ is employed to fabricate an in operando, self-growing solid electrolyte interphase (SEI) on LiFePO4 electrodes. This treatment prevents iron dissolution at high temperatures, thus extending the life cycle of the batteries. The APPJ process facilitates the plasma-induced grafting of hydrophilic functional groups on the LiFePO4 surface, leading to the formation of an amorphous a-FePO4·H2O thin layer and a unique core-shell SEI layer. This SEI layer significantly improves cycle performance by suppressing iron dissolution, especially under high-temperature conditions.

We also used a tornado-type APPJ system to modify soft carbon (SC) anode materials. APPJ treatment enhances the surface properties of SC by introducing oxygen-containing functional groups and nitrogen doping. This results in a substantial reduction in contact angle, increased hydrophilicity, and improved electrolyte penetration. The nitrogen doping enhances conductivity, reversible capacity, and rate capability of the SC anode. The modified SC electrode demonstrates a significant improvement in reversible charge and discharge capacity and overall performance compared to the pristine SC electrode.

 Overall, APPJ technology plays a crucial role in improving the thermal stability, electrochemical performance, and efficiency of LIBs by modifying the electrode surfaces and introducing beneficial chemical functionalities.

Journal Papers: Soft Carbon,  LiFePO4 

-Energy Materials: Supercapacitors-

We developed the reduced graphene oxide (rGO)-SnO2 nanocomposites on carbon cloth using a CO2 tornado-type atmospheric-pressure plasma jet (APPJ). The tornado-type APPJ enhances mixing of reactive plasma species, ensuring uniform reactions during calcination. These nanocomposites serve as active electrode materials in flexible supercapacitors with a polyvinyl alcohol (PVA)-H2SO4 gel electrolyte. The APPJ treatment optimizes the electrochemical performance of the supercapacitors, achieving excellent capacitance and durability even after extensive cycling. The analysis reveals a balanced contribution from both pseudocapacitance and electrical double-layer capacitance, indicating an efficient energy storage mechanism. The study shows that these supercapacitors achieve energy density comparable to other advanced APPJ methods, highlighting tornado-type APPJ's potential to enhance supercapacitor performance.

Journal Papers: Supercapacitors, CO2 plasma for rGO-SnO2

-Semiconductor Materials-

Atmospheric pressure plasma (APP) is a versatile tool for enhancing oxide semiconductor properties. It can dope these semiconductors with specific elements or functional groups, improving conductivity and tailoring electronic properties for targeted applications. Furthermore, in defect engineering, APP can introduce or passivate defects in oxide semiconductors, enabling precise tuning of their electrical properties. This capability is particularly crucial for advancing applications in electronics and optoelectronics, where precise control over material properties is essential for optimal device performance.

Journal Paper: Semiconductor  Zn0.9Mg0.1O

-BGA Process-

Solder Wettability for IC BGA Package

Addressing surface oxidation issues in IC chips is critical because it directly impacts solderability in the packaging industry. Advanced technologies, such as direct current-atmospheric pressure plasma (DC-APP), can effectively tackle this challenge by improving surface wettability and enhancing the soldering process. The study shows that even a brief 0.5-second plasma treatment can significantly transform a copper substrate's surface properties, making it hydrophilic and promoting a uniform copper oxide layer. This leads to better solder spreading, improved wettability, and reliable long-term performance, as evidenced by stable intermetallic compound (IMC) growth rates and enhanced mechanical properties. 

Journal: Plasma-Activated Reflow Soldering, Solderability Enhancement on PCB, Achieving Selective Cleaning, Solder Wettability

-Food Technology-

Plasma-Seared Salmon: Technology Leads a Culinary Revolution. 

Traditional searing methods, such as Aburi (炙り/あぶり), rely on gas torches fueled by hydrocarbons, which lack carbon-reduction benefits. Plasma searing, on the other hand, uses air to treat raw fish fillets, achieving comparable results while offering a more sustainable alternative. Aburi, a culinary technique originating in Japanese cuisine, involves rapidly heating the surface of ingredients with a high-temperature flame, creating a slightly charred, golden-brown or dark-brown exterior while preserving internal tenderness. Commonly applied to sushi, tuna, salmon, beef, and scallops, aburi enhances aroma and flavor by adding a smoky note, softening surface fats, and creating a crispy exterior with a tender interior. Plasma searing aims to replicate these effects while reducing environmental impact, with ongoing studies validating food safety and exploring the development of practical machines for processing Japanese cuisine. 

-Plasma Yakisugi-

Plasma Yakisugi (or Plasma Shou Sugi Ban) is an advanced surface-modification technology that combines the traditional Japanese wood-preservation technique of Yakisugi (焼杉, charring cedar wood) with modern Plasma Technology (such as atmospheric-pressure plasma or thermal plasma torches). 

Benefits:

• Precise Thermal Control: Instead of standard gas torches or direct combustion, high-density plasma energy (ion-gaseous flames/jets) delivers uniform, ultra-precise surface heating.

• Surface Energy Modification: Plasma treatment modifies surface energy and chemical bonds (polar functional groups) in wood cells at the microscopic level, drastically improving paint, stain, or protective-coating adhesion without overdamaging the timber's structural integrity.

• Eco-Friendly Process: It allows fine-tuned carbonization without relying on fossil fuel-intensive open flames or excessive chemical preservatives.