The Korean Society of Surface Science and Engineering

Seawater secondary batteries are gaining attention as a new energy storage system that offers a stable supply of resources, cost savings, and enhanced safety compared to traditional lithium-ion batteries (LIBs). One of the key motivations for considering seawater batteries as an alternative energy storage system is the scarcity and high cost of resources like lithium and cobalt, as well as safety concerns related to the use of organic electrolytes in LIBs. Seawater secondary batteries utilize sodium ions and leverage the abundant and low-cost seawater as the cathode material, which reduces costs and allows for the easy construction of large-scale systems without the need for frequent electrode material replacement. Additionally, the natural cooling effect of seawater facilitates thermal management of the battery system, helping to reduce the overall system size. The reaction mechanisms and components of seawater secondary batteries are discussed. The oxidation-reduction reactions of sodium ions during charge and discharge, as well as the specific reactions occurring at the anode and cathode, are explained. In the main body of this paper, the influence of these reactions on the electrochemical performance of seawater secondary batteries is also examined. In particular, research findings related to carbon-based materials used as anodes, various composites, non-aqueous electrolytes as anolytes, and cathode catalysts are discussed in detail. In conclusion, while seawater secondary batteries hold great potential as an alternative energy storage system, there are still several challenges that need to be addressed before commercialization. Continued research is required to improve battery performance and ensure long-term stability through material advancements, as well as to explore cost reduction strategies for large-scale commercialization.

Sewater, Battery, Rechargeble

This study presents a lithium electroplating technology designed to enhance the quality of lithium anodes for next-generation lithium metal batteries. We investigate the electroplating process to achieve a high-density lithium layer. By employing atmospheric-pressure plasma treatment on copper current collectors and applying uniaxial pressure during the electroplating process, significant progress was made in improving the properties of the electrodeposited lithium. Furthermore, we analyze the factors contributing to performance degradation at low E/C ratios (electrolyte-to-capacity ratio) and discuss strategies for the commercialization of electroplated lithium as anode material for lithium metal batteries.

Lithium metal electrodeposition; charge-discharge stability; high-density lithium metal; protective coating; electrode behavior; lithium metal battery

In conventional catalyst supports for fuel cell membrane electrode assemblies (MEA), carbon-based materials such as activated carbon, carbon nanotubes, and graphene are commonly used to enhance the performance of platinum catalysts. However, their reliance on fossil resources raises environmental concerns. In this study, we explored an alternative approach by producing carbon fillets, functioning as catalyst supports, from jellyfish, considered marine waste, and seaweed roots, a byproduct of fishery processing. Six different samples were fabricated under varying conditions and characterized using Brunauer–Emmett–Teller specific surface area analysis, X-ray diffraction, X-ray photoelectron spectroscopy, and organic elemental analysis. Among them, the seaweed-derived sample, activated with C: KOH at a ratio of 1:1 demonstrated the best performance with a high surface area of 1360 m^²/g and no detectable impurities. Consequently, the MEA catalyst support developed in this study shows promising potential for future applications in sustainable fuel cell technologies.

Jellyfish; seaweed root; catalyst support; membrane electrode assembly; fuel cell

Stainless steel used in the semiconductor industry requires high surface quality and corrosion resistance, making ultra-cleaning processes essential. This study investigated the effects of various electrolyte compositions with different ratios of phosphoric acid and sulfuric acid on the electropolishing performance and Cr/Fe ratio of stainless steel. As the phosphoric acid content increased, the optimal voltage range for maintaining stable current density narrowed, but surface roughness improved due to its oxidation-promoting effect. In contrast, higher sulfuric acid content resulted in limited improvements in surface quality and the Cr/Fe ratio. These findings present a method for optimizing electrolyte composition and passivation time to effectively enhance the surface quality and corrosion resistance of stainless steel required in the semiconductor industry.

Electropolishing; Phosphoric acid; Stainless steel; Surface roughness; Cr/Fe ratio

Corrosion of metals poses a threat to structural integrity in various industrial sectors and can intensify with prolonged exposure. This study proposes an efficient method for corrosion detection and analysis. A heuristic approach was used to derive a corrosion matrix composed of corrosion area colors and specimen surface colors, utilizing the CIEDE2000 color difference criterion. By converting specimen images into optical density space and performing color normalization, consistency in color changes was maintained during long-term observation. The combination of Optical Density transformation and HSV color space transformation provides an effective and consistent method for analyzing the corrosion process. This approach is expected to enhance the performance of corrosion monitoring systems and improve structural safety.

Corrosion detection; CIEDE2000 color difference; Optical density space; Color normalization

In this study, we developed and evaluated a multilayer nickel/zinc-nickel (Ni/Zn-Ni) coating using a single electrodeposition bath with controlled potential. Traditional zinc-nickel coatings offer superior corrosion resistance compared to pure zinc, particularly with an optimal Ni composition of 12-15 wt.%. However, we utilized a pulse-reverse potential (PRP) technique to create multi layers of Zn-Ni alloy and pure Ni. Linear sweep voltammetry (LSV) was employed to determine appropriate potential ranges for selective Zn-Ni alloy and Ni layer electrodeposition. The coating microstructure was analyzed using scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS). X-ray diffraction (XRD) revealed γ-phase Zn-Ni alloy in both direct current (DC) and PRP samples, but additional Ni phase was found in case of PRP. Corrosion resistance was evaluated using potentiodynamic polarization in 3.5 wt.% NaCl solution, where PRP coatings exhibited significantly lower galvanic couple current density and higher couple potential, demonstrating improved corrosion resistance compared to the DC case. Additionally, Vickers hardness testing indicated that the PRP coating had higher surface hardness than DC case. This Ni/Zn-Ni multilayer approach shows potential as a robust anti-corrosion solution, offering enhanced mechanical properties and corrosion resistance.

Zn-Ni alloy; Nickel; Electrodeposition; Multi-layer; Pulse-reverse potential

The effect of PVdF on the electrochemical activity of composite electrodes for Li battery was analyzed using the PVdF-aqueous solution as a model system in terms of fractal dimension(D_f). To this end, specimens with different pore structures were prepared by controlling the electrode density and loading, and their electrochemical behavior under diffusion control was analyzed by cyclic voltammetry(CV) and electrochemical impedance spectroscopy(EIS). The CV results showed a clear difference in D_f depending on the pore structure and confirmed that the electrochemical deactivation effect of PVdF is different for different pore structures. Particularly, its deactivation effect was larger at the macroscopic pore level, suggesting that it may be responsible for the inhomogeneous reaction across pore size regions. On the other hand, when EIS was applied, the overall D_f was similar to the value from CV, but the ability to distinguish differences in D_f according to pore structure was relatively low.

Lithium battery; Electrode; Pore structure; Fractal dimension; PVdF

This study proposes an image segmentation technique utilizing the U-Net model to effectively segment the cross-sections of corroded specimens. The proposed model, leveraging an encoder-decoder architecture with skip connections, enables high-resolution segmentation, which is advantageous for the precise delineation of complex corroded areas. After training the model on a labeled image dataset, performance evaluation using test images demonstrated that the proposed U-Net model achieved high accuracy and IoU scores, thereby confirming its excellent performance. These results indicate that machine learning-based long-term image analysis can contribute to the efficient and straightforward segmentation of specimens.

Corrosion specimen; Image segmentation; U-Net