Aqueous zinc-ion batteries (ZIBs) have emerged as promising candidates for safe and sustainable energy storage systems. However, conventional ZIBs face critical challenges, such as zinc dendrite formation, corrosion, and passivation, primarily due to their unstable deposition‒dissolution mechanism compared with the “rocking-chair” mechanism of lithium-ion batteries. This review presents a critical assessment of the past decade’s significant advances in “rocking-chair” ZIBs, with a particular focus on Zn²⁺-intercalation anodes. Four major classes of zinc-metal-free anodes are systematically discussed, highlighting their distinctive physicochemical features and zinc storage mechanisms. The development trajectory of anode materials is traced from early developments in transition metal dichalcogenides to emerging hybrid materials, with a focus on key challenges in ionic diffusion and electronic conductivity. Furthermore, we summarize the underlying working principles, essential design criteria, and material optimization strategies. Finally, future research opportunities and technological challenges are outlined to advance rocking-chair ZIBs toward practical deployment in applications ranging from grid-scale storage to portable electronics. This review provides critical insights and design guidance for enabling the next generation of high-performance, commercially viable ZIBs.

The shift towards green hydrogen production is imperative for accomplishing sustainable energy goals, particularly through seawater electrolysis. However, the simultaneous occurrence of the chlorine evolution reaction (CER) poses a substantial challenge by competing with the oxygen evolution reaction at the anode, thereby reducing the catalyst's efficiency and selectivity. This review critically examines the modern strategies for mitigating CER, focusing on the development and application of advanced nanomaterials. The emphasis is on transition metals and their oxides, 2D materials, layered double hydroxide-based electrocatalysts, and core–shell nanostructure-based electrocatalysts, highlighting their electrocatalytic properties, structural advantages, and potential drawbacks. Moreover, this review presents a balanced assessment of their benefits, including improved catalytic activity and stability, and their limitations, such as cost and scalability. Furthermore, this review reports the advantages and disadvantages of the CER, revealing that competing CERs can suppress the HER Faradaic efficiency by 20%–30% in chloride-rich electrolytes (~ 0.5 mol L⁻¹ Cl⁻). The conclusion and future outlook focus on the key findings, highlighting the necessity for continued innovation in material design and engineering. This review aims to guide researchers and industry stakeholders in developing more efficient and sustainable technologies for seawater electrolysis.