Hyun-Jong Kim

Li recovery from spent Li-ion batteries is essential for establishing a sustainable Li supply chain. Here, we demonstrate an integrated electrochemical system that couples Li+ accumulation with the hydrogen evolution reaction (HER) in a modified proton exchange membrane water electrolysis configuration. This study serves as a fundamental proof-of-concept utilizing a synthetic model solution representing a pre-purified transition-metal-free leachate. By supplying a Li-containing anolyte and circulating deionized water in the cathode compartment, Li+ is transported across the membrane under an applied electric field and progressively accumulated in the catholyte, while HER proceeds as a value-added co-reaction. Systematic investigation shows that interfacial mass transport and membrane properties significantly influence Li+ migration and overall energy efficiency. Long-term operation confirms that Li+ can be accumulated to concentrations exceeding 4 M, approaching the solubility limit of LiOH. Subsequent evaporation of the concentrated catholyte yields solid LiOH without detectable impurities. Unlike the conventional causticization process, which inherently requires multi-stage crystallization to achieve battery-grade purity (>99.5%), our electrochemical configuration directly produces nearly 100% pure LiOH without any additional purification steps. Energy analysis shows that the integrated electrochemical concentration-evaporation process requires less energy than direct evaporation of dilute LiOH solutions. These results highlight the potential of electrochemically driven concentration as a practical platform enabling integrated Li recovery and energy generation.

Li recovery from spent Li-ion batteries is essential for establishing a sustainable Li supply chain. Here, we demonstrate an integrated electrochemical system that couples Li+ accumulation with the hydrogen evolution reaction (HER) in a modified proton exchange membrane water electrolysis configuration. By supplying a Li-containing anolyte and circulating deionized water in the cathode compartment, Li+ is transported across the membrane under an applied electric field and progressively accumulated in the catholyte, while HER proceeds as a value-added co-reaction. Systematic investigation shows that interfacial mass transport and membrane properties significantly influence Li+ migration and overall energy efficiency. Long-term operation confirms that Li+ can be accumulated to concentrations exceeding 4 M, approaching the solubility limit of LiOH. Subsequent evaporation of the concentrated catholyte yields solid LiOH without detectable impurities. Unlike the conventional causticization process, which inherently requires multi-stage crystallization to achieve battery-grade purity (>99.5%), our electrochemical configuration directly produces nearly 100% pure LiOH without any additional purification steps. Energy analysis shows that the integrated electrochemical concentration-evaporation process requires less energy than direct evaporation of dilute LiOH solutions. These results highlight the potential of electrochemically driven concentration as a practical platform enabling integrated Li recovery and energy generation.

Reliable and noninvasive monitoring of glucose remains a critical challenge for wearable healthcare devices. Conventional enzymatic sensors, while selective, suffer from limited stability and short operational lifetimes, highlighting the need for robust nonenzymatic alternatives. Here, we report a nonenzymatic, noninvasive glucose biosensor fabricated through the combination of laser irradiation (LI) and electroless plating (ELP). LI of a SnO₂/polyurethane acrylate (PUA) composite selectively exposed catalytic sites, enabling uniform Cu/Ni/Au metallization via ELP. The resulting electrodes were well-formed, exhibiting low resistivity (21.94 ± 1.09 mΩ·cm) and strong mechanical stability, maintaining conductivity even after 100,000 folding cycles at a bending radius of 5 mm. Functionalization with catalytic Pt/C endowed the electrodes with high catalytic activity, yielding reliable cyclic voltammetry (CV) responses and superior glucose detection capability. Compared with a commercial electrode, the LI-ELP biosensor achieved nearly 18-fold higher sensitivity (16.3 ± 1.40 vs 0.92 ± 0.10 mA mM^-1 cm^-2) and improved linearity (0.96 vs 0.94) over the 0-0.5 mM glucose range. The superior performance is attributed to the enlarged active surface area, optimized electrode structure, and efficient catalyst utilization, which collectively reduced overpotentials and enhanced charge-transfer efficiency. Overall, these findings establish LI-ELP as an effective and scalable strategy for fabricating durable, conductive, and efficient electrodes, highlighting its strong potential for next-generation wearable biosensors and broader nonenzymatic electrochemical sensing applications.

Developing next-generation thermal-neutron-shielding and -absorbing materials for the safe storage and transportation of spent nuclear fuel is a topic of active research in academia. Gadolinium (Gd) boasts superior neutron absorption capacity compared with other nuclei. Consequently, it has garnered significant attention as a potential replacement for boron in spent nuclear fuel (SNF) applications. In this study, the austenitic stainless steels 304 and 316 and the duplex stainless steel 5A were reinforced with 2 wt.% of gadolinium to explore their thermal-neutron-absorbing efficiency. Their properties were then compared with commercial-grade borated stainless steel, as per ASTM standard A887. After the inclusion of Gd, both the yield strength and ultimate tensile strength of the alloys slightly increased, which was attributed to the evenly distributed Gd intermetallics within the matrix. However, the elongation rate was reduced. The Charpy impact absorption energy also decreased. The influence of the Gd intermetallic was further explored by examining the fractography. While the corrosion resistance of the alloy slightly diminished after the addition of Gd, its neutron absorption capacity demonstrated superior performance, especially when the Gd content was equivalent to that of boron. Although most properties of the experimental alloy deteriorated after the Gd addition, they still outperformed commercial borated stainless steel, suggesting that this alloy might be a promising candidate for SNF applications.