Seunghoon Nam

In the quest for sustainable and cost-effective energy storage solutions, sodium-ion batteries (SIBs) have emerged as a promising alternative to lithium-ion batteries, owing to their similar chemical compositions, mechanisms, and compatibility with existing battery technologies. Despite their potential, SIBs face challenges such as lower capacity and structural instability, which hinder their widespread adoption. This paper provides a comprehensive overview of cathode materials used in SIBs, focusing on their electrochemical properties, limitations, and the ongoing research aimed at overcoming these challenges. We delve into the current state of SIB technology, highlighting the critical role of cathode materials in enhancing the performance, durability, and cost-effectiveness of SIBs. Furthermore, we explore future directions for research and development, including novel materials and innovative approaches to improve the capacity and structural stability of SIBs. By addressing these key issues, this paper aims to contribute to the advancement of SIB technology and its application in next-generation energy storage systems.

Green hydrogen is being considered as a next-generation sustainable energy source. It is created electrochemically by water splitting with renewable electricity such as wind, geothermal, solar, and hydropower. The development of electrocatalysts is crucial for the practical production of green hydrogen in order to achieve highly efficient water-splitting systems. Due to its advantages of being environmentally friendly, economically advantageous, and scalable for practical application, electrodeposition is widely used to prepare electrocatalysts. There are still some restrictions on the ability to create highly effective electrocatalysts using electrodeposition owing to the extremely complicated variables required to deposit uniform and large numbers of catalytic active sites. In this review article, we focus on recent advancements in the field of electrodeposition for water splitting, as well as a number of strategies to address current issues. The highly catalytic electrodeposited catalyst systems, including nanostructured layered double hydroxides (LDHs), single-atom catalysts (SACs), high-entropy alloys (HEAs), and core-shell structures, are intensively discussed. Lastly, we offer solutions to current problems and the potential of electrodeposition in upcoming water-splitting electrocatalysts.

As opposed to nano‐Si anodes, Si‐microparticle (Si‐MP)‐based negative electrode is still in an immature stage due to the fragility of particles of which dimension is farther from the critical size of Si. In terms of binder chemistry, the established strategies for nano‐Si anode can be moderately transferred to designing functional binders for commercially available Si‐MP. However, only a few studies have reported acceptable electrochemical properties of Si‐MP in the level of designing novel‐binder systems. Herein, the ionically crosslinked polyacrylate (PANa_0.8Fe_y) inspired by metallo‐supramolecular polymers is introduced as a binder for Si‐MP anode. Although cracking of Si‐MP is inevitable during cycles, the electrode components can effectively be confined within the supramolecular network, which reversibly adjusts its architecture via iron (Fe³⁺)‐carboxylate coordination. With appropriate compositions, the incorporation of ferric ion to sodium polyacrylate allows the Si‐MP to exhibit an excellent round‐trip capacity of ∼1400 mAh g⁻¹ after 400 cycles. The resulting electrochemical performance is demonstrated by several correlated factors: (i) type of supramolecular interactions, (ii) effect of cations (Na⁺/Fe³⁺) on the conformation of polymer, and (iii) mechanical properties of the electrode.

Silicon has been considered as a promising anode material due to its high theoretical capacity (3579 mAh g⁻¹), however, it suffers from capacity degradation owing to the series of multiscale fractures in the electrode caused by the volume variation (≈300%) during phase transitions. The molecular/structural design of polymeric binders has been pivotal in overcoming the challenges to improve the integrity of Si anode via strong interactions between active materials and binders. In this respect, the covalently crosslinked polyacrylamide (PAM) network, which effectively maintains its mechanical strength and shape, is introduced as a novel binder system for Si active materials. Unlike the thermal crosslinking, the abundant polar‐functional groups, related to the strong interactions between Si and polymer, are not sacrificed in their network by virtue of the in situ polymerization. Through the PAM gel, the Si‐based electrode exhibits a superior capacity of ≈1526 mAh g⁻¹ at an optimized crosslinker concentration after 500 cycles. In addition, the effect of the chemical/mechanical properties of PAM gel on the electrochemical properties of Si is adequately elucidated. The results will provide meaningful insight regarding the design of novel binders, especially in the application of the covalently crosslinked structure to Si‐based electrodes.