The development of efficient, stable, and cost-effective bifunctional electrocatalysts for the hydrogen evolution reaction (HER) and the chlorine evolution reaction (CER) is critical for energy-saving chlor-alkali production and direct seawater...

Four-electron iodine conversion chemistry has recently emerged as a highly promising strategy for overcoming the intrinsic energy-density limitations of conventional iodine-based cathodes. The conventional two-electron I−/I0 redox reaction suffers from a limited theoretical specific capacity of ∼211 mAh g−1, while the four-electron I−/I0/I+ conversion pathway doubles the electron-transfer number and elevates the operating potential, delivering a theoretical specific capacity of ∼422 mAh g−1 and a markedly enhanced energy density. In this review, we systematically summarize the fundamental principles, historical evolution, and recent advances of four-electron iodine conversion in diverse rechargeable battery chemistries. We elucidate the intrinsic limitations of two-electron iodine reactions, identify the stabilization of high-valent iodine (I+) as the central scientific challenge, and trace the development of four-electron iodine chemistry from aqueous Zn–I2 batteries to organic lithium–iodine systems and all-solid-state configurations. Thereafter, we critically analyze the major regulation strategies that enable reversible I−/I0/I+ conversion, such as halogen coordination, molecular coordination chemistry, and microenvironment engineering. Finally, we identify key challenges and future opportunities for four-electron iodine batteries, including materials- and structure-level optimization and external-field-assisted electrochemical regulation, among other promising directions.

Aqueous zinc-ion batteries (AZIBs) have emerged as promising candidates for large-scale energy storage systems due to their high safety, low cost, and environmental friendliness. However, the zinc (Zn) anode faces a series of side reactions, including hydrogen evolution, dendrite growth, corrosion, and passivation, leading to irreversible loss of active Zn material and a significant reduction of cycling stability of the Zn anode. To mitigate the impact of these issues, an excess of Zn anode is commonly employed to ensure a continuous supply of Zn during long-term operation. However, the use of excess Zn results in a practical energy density of AZIBs that is far below the requirements for commercialization. Improving Zn anode utilization rate (ZUR) and optimizing the negative/positive electrode capacity ratio (N/P) are effective pathways to achieve high energy density. This review systematically summarizes the challenges associated with Zn anodes with high ZUR and provides a detailed discussion on modification strategies to improve the ZUR from three aspects: the anode, electrolyte, and separator. Finally, we look ahead to the future development directions and prospects of Zn anodes with high ZUR and AZIBs with high energy density. With ongoing technological advancements and continuous innovation, we believe AZIBs have the potential to overcome current bottlenecks and contribute to the global development of sustainable energy systems.

ABSTRACT The electrocatalytic synthesis of urea from carbon dioxide and nitrate represents a sustainable route, with the C─N coupling between *CO and *NO intermediates being critical. However, achieving high efficiency remains challenging due to insufficient control over intermediate adsorption and reaction pathways. In this work, we reveal that the coordination number (CN) of Cu inversely regulates the adsorption strength of *CO and *NO, while C─N coupling activity follows a volcano‐type relationship with CN. Alloying Cu with intrinsically inert Ga atoms lowers the CN of Cu, upshifts d ‐band center, and finely tunes intermediate adsorption, thereby facilitating the formation of the key *ONCO. The optimized Cu 0.875 Ga 0.115 catalyst, with a moderate CN of 9.3 situated between its counterparts (6.0 and 12.0), balances adsorption and coupling activity, delivering a desirable urea yield rate of 575.6 mmol h −1 g −1 and a Faradaic efficiency of 30.4% at −1.4 V versus RHE. This work underscores coordination engineering as an effective strategy for guiding efficient C─N coupling toward urea synthesis.

ABSTRACT Aqueous zinc‐iodine batteries are promising candidates for safe and low‐cost energy storage but suffer from severe degradation under low‐temperature and high‐rate conditions due to electrolyte freezing, iodine dissolution, sluggish ion transport, and interfacial instability. Herein, we report a multiscale confinement electrolyte by introducing high‐concentration Ca(ClO 4 ) 2 and a small amount of starch into a Zn(OTf) 2 system to regulate solvation structure, iodine chemistry, and electrode interfaces simultaneously. The strong hydration capability of Ca 2+ reconstructs the hydrogen‐bond network, reduces water activity, suppresses ice crystallization, and preserves ion transport at subzero temperatures. Meanwhile, Ca 2+ confines iodide and polyiodide species through strong electrostatic interactions, thereby suppressing I 2 dissolution, inhibiting shuttle effects, and mitigating active material loss. Starch further constructs an interfacial confinement layer on the Zn anode, inhibiting parasitic reactions, reducing by‐product formation, and guiding uniform Zn deposition. Benefiting from these synergistic effects, Zn||I 2 batteries deliver an exceptional rate capability of 15 A g −1 and achieve ultrastable cycling over 60 000 cycles at this ultrahigh rate. Moreover, the batteries operate reliably at –40°C, delivering over 3600 h of cycling at 0.5 A g −1 with 95.8% capacity retention. High‐loading pouch cells and a preliminary 1.1 Ah‐level demonstration further confirm the practical scale‐up potential of this electrolyte strategy.

Aqueous zinc-ion batteries (AZIBs) hold great promise for large-scale energy storage due to their safety, low cost, and environmental compatibility. However, AZIBs face severe challenges, including cathode dissolution and anode dendrite growth, while their reliability under extreme conditions is limited by electrolyte instability. Electrolyte additives, especially organic molecule additives, provide an effective and cost-efficient strategy to address these issues. Herein, we report a novel nontoxic, green, low-cost, and water-miscible organic molecule additive used as a co-solvent, which synergistically reconstructs the solvation structure of Zn2+ and disrupts the strong bonding among H2O molecules by modulating the electrostatic interactions among Zn2+, H2O, and ClO4-, suppressing water-induced side reactions and lowering the freezing point of the electrolyte, thereby optimizing Zn ion migration and deposition behavior. Consequently, Zn||Zn batteries exhibit excellent performance at ambient temperature (25 degrees C) and can still achieve over 2500 h of cycling life at a low temperature of-40 degrees C. It is worth noting that Zn||Zn batteries can also operate stably under the ultra-low temperature condition of-60 degrees C. Additionally, the co-solvent electrolyte suppresses the dissolution of vanadium-based cathodes under low-rate conditions, enabling Zn||VO2 batteries to maintain a high capacity retention of 91 % after 600 cycles at 0.5 A g-1 under ambient temperature (25 degrees C). Furthermore, at-40 degrees C, the Zn||VO2 battery can operate for over 1000 hat a current density of 0.1 A g-1. This work provides anew strategy for constructing high-performance AZIBs over a wide temperature range. (c) 2025 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. and Science Press. All rights are reserved, including those for text and data mining, AI training, and similar technologies.

Four-electron aqueous zinc-iodine (Zn-I2) batteries offer twice the theoretical capacity of conventional two-electron systems, but their development is hindered by the instability of high-valent iodine ion (I+) species, which causes incomplete reactions and poor reversibility. The freezing point of aqueous electrolytes and sluggish kinetics further hinder four-electron transfer at subzero temperatures. Although antifreezing electrolytes based on Zn(ClO4)2 provide a reliable medium for subzero operation, efficient I+ stabilizers are still lacking. Here, we introduce glycine hydrochloride (GY) as a molecular additive that, upon hydrolysis, supplies chloride and oxygen donors to form a unique bidentate coordination with I+. This coordination stabilizes the high-valence intermediate and enables highly reversible four-electron iodine conversion. Benefiting from this mechanism, Zn-I2 batteries deliver near-theoretical capacity and excellent reversibility at ultra-low-temperature. At 0.5 A g-1, the cell operated stably for over 3500 cycles, with an average Coulombic efficiency of 99.95 % with the 3 M Zn (ClO4)2 + 1 M GY electrolyte. Even at a low current density of 0.05 A g-1, the discharge capacity remained close to 400 mAh g-1 value with a capacity retention of 96.8 %, accompanied by stable cycling over 2800 h and an efficiency of 99.74 %. These results highlight the robustness of the bidentate coordination strategy for enabling highly reversible four-electron conversion under ultralow conditions.

Static aqueous zinc–bromine batteries (ZBBs) are regarded as highly promising systems for large-scale energy storage owing to their high theoretical capacity and intrinsic safety. However, severe self-discharge caused by polybromide (Brn−) shuttling critically limits their practical application. Herein, a series of imidazolium-based ionic liquid bromine complexants with different alkyl chain lengths are systematically investigated to elucidate the balance between complexation strength and reaction kinetics. The results demonstrate that 1‑butyl‑3-methylimidazolium bromide (BMIMBr) achieves an optimal kinetic-thermodynamic balance, enabling effective stabilization of Brn− while maintaining fast reaction kinetics and high electrochemical reversibility. Benefiting from this balance, BMIMBr-optimized static ZBBs deliver nearly 10,000 stable cycles at a high rate of 5 C and sustain ultralong-term stable operation for up to 5000 h at a low rate of 0.2 C. Moreover, this system is successfully extended to 300 mAh and 1 Ah pouch cells, which maintain Coulombic efficiencies close to 100% even under high-rate and large-capacity conditions, demonstrating excellent scalability. Overall, these results indicate that achieving a rational kinetic-thermodynamic balance is a key design principle for high-performance and scalable static ZBBs.

The practical application of aqueous zinc metal batteries remains impeded by uncontrolled dendrite growth and parasitic side reactions, arising from the absence of a robust and compact solid-electrolyte interphase (SEI). Herein, we propose a dynamic interfacial regulation strategy enabled by the electrochemical hydrogenation of organic molecules. This approach stabilizes the local pH and induces the uniform nucleation and self-limiting growth of zinc hydroxide sulfate (ZHS), yielding a dense and horizontally oriented protective layer. The resulting compact ZHS layer exhibits a low Zn2+ migration barrier, thus facilitating efficient ion transport while suppressing water-induced side reactions. Consequently, symmetric cells deliver over 4000 h of stable cycling and 400 h even at 90 % Zn utilization rate. Zn-V2O5 full cells retain 85 % capacity after 5000 cycles at 5 A g- 1, and Zn-AC capacitors remain stable for 200 000 cycles. This work introduces an electrochemical hydrogenation mediated SEI formation paradigm, offering a new route toward dendrite-free and durable aqueous zinc metal anodes.

ABSTRACT Electrolytic Zn‐MnO 2 batteries (EZMBs) are considered a promising technology for grid‐scale energy storage due to their low cost, high specific capacity, high operating voltage and safety. However, the tradeoff between the mildly acidic environment for high‐efficiency zinc deposition on anode and the high concentration of protons required to trigger the MnO 2 /Mn 2+ conversion reaction on cathode leads to the pH mismatch issue, finally causing the instability and short lifespan of current EZMBs. In this study, a synergetic anion–proton interactive (SAPI) electrolyte regulation strategy is reported to balance the pH mismatch, which can not only regulate the electrode‐electrolyte interfacial microenvironment to promote the deposition of highly (002)‐oriented Zn plane with high resistance to the hydrogen evolution reaction and corrosion on anode, but also accelerate the redox reaction of MnO 2 /Mn 2+ conversion on cathode, simultaneously. As a result, the SAPI electrolyte enables a 40‐fold lifespan enhancement of over 5000 cycles at a current density of 10 mA cm −2 in Zn‐Zn symmetric cells as compared to the pristine electrolyte. Furthermore, the EZMBs in SAPI electrolyte achieve an elevated average discharge voltage of 0.4 V and about 10‐fold stable cycling lifespan than the pristine one. This strategy provides novel insights into designing long‐life EZMBs and orientational deposition of zinc anode.

Iodine-based batteries have emerged prominently in grid energy storage due to their cost-effectiveness and versatility. However, traditional iodine cathodes featuring I-/I0 mechanisms struggle to meet the current demands for high-energy-density batteries, considering their limited specific capacity and voltage. Here, we discover a unique eight-electron-transfer asymmetric three-stage conversion of iodine facilitated by the formation of interhalogens. This mechanism involves a three-stage sequential charging from I-/I0, to I0/ICl2-, and finally ICl2-/ICl4-, with the prolonged third charging plateau significantly enhancing the specific capacity to 809.2 mAh g-1 of I2. During discharge, the cathode undergoes highly reversible but asymmetric conversions, with ICl3- as the intermediate. The mechanism is achieved by a regulated "chloride-in-acid" electrolyte with interlocking H-bond structures, which effectively reduces the free water content and stabilizes the interhalogen species. The iodine-hydrogen gas battery demonstrates stable cycling performance with an average Coulombic efficiency exceeding 98.2% for over 1000 cycles and an increased voltage from 0.47 to 0.75 V compared with the I-/I0 mechanism, which can be further enhanced to 1.43 V by utilizing zinc anode. This study broadens the application of interhalogen chemistry into conversion reactions, presenting great prospects for high-energy-density aqueous batteries.

The reversibility of zinc (Zn) anode is subject to adverse reactions. Herein we design a dynamic modulation strategy via enol-keto tautomerism to inhibit the side reactions, thus improving the reversibility of the Zn anode. Density functional theory calculations and experimental results demonstrate the keto form of additives can be adsorbed on the Zn anode, inhibiting dendrite growth, while the enol form can serve as a bidentate ligand to participate in the construction of solvation sheath for Zn 2+ , enhancing the kinetics of Zn 2+ transport, simultaneously suppressing water activity and reducing HER and corrosion. Consequently, the Zn anode with optimal electrolyte additive achieves high reversibility, where Zn||Zn symmetric cells operate over 4000 h at 10 mA cm −2 /10 mAh cm −2 , and Zn||Cu asymmetric cells have a life for 930 h at 10 mA cm −2 /10 mAh cm −2 . Further, this dynamic modulation enables Zn||V 2 O 5 full cells to work over 5000 cycles with a capacity retention of 83% at 5 A g −1 , and the Zn||Br 2 pouch cells deliver a high capacity of ∼180 mAh. This study offers an original perspective on the dynamic regulation of electrolytes for Zn anode.

Aqueous Zn batteries (AZBs) suffer from poor Zn anode reversibility. To address this issue, excess Zn foil is often utilized to prolong the cycle life, but it reduces the actual battery energy density. In this work, we use methylurea molecules to in situ form a solid electrolyte interphase (SEI) layer on the Zn anode, achieving reversible Zn plating/stripping with a maximal Coulombic efficiency (CE) of 99.99% and extending the anode's lifespan to 4500 cycles. Leveraging this highly reversible chemistry, we fabricate and test various anode-free Zn batteries. An anode-free Zn-AC cell exhibits stable cycling for exceeding 5000 cycles, an anode-free Zn-I-2 battery with high specific capacities achieves a stable cycle life of 1000 cycles, and an anode-free Zn-Br-2 battery with a high areal capacity of 4 mAh cm(-2) demonstrates a stable cycle life of 450 cycles. Characterization of the SEI using TEM and DFT calculations reveal the formation mechanisms of the ZnCO3- and ZnS-rich amorphous SEI layer. These results indicate that the design of desirable SEI compositions could pave the way for developing low-cost, high-perfor-mance anode-free AZBs.

The multicomponent synergistic effect has become increasingly important for electrocatalysis; however, there remain large unexplored compositional and structural spaces. Here, an unconventional high-entropy oxide (HEO) with inner metallic coordination interactions and surface medium-entropy metal-OH for durable proton exchange membrane water electrolyzers (PEMWEs) is presented. The metallic clusters inside the HEO particles generate the inner metallic coordination interactions that reserve electrons, with a multicomponent effect, to inhibit Ru/Ir overoxidation and switch reaction mechanisms toward an exclusive adsorbate evolution mechanism for acidic oxygen evolution reaction (OER). Surface medium-entropy metal-OH groups enable adaptive interfacial water networks to trap reactive water and promote proton transfer, reducing mass transport resistance at large current densities. Resultantly, this RuIrNiCoCrO2-incorporated PEMWEs achieve the ultralow voltages of 1.71 V@2.0 A cm-2 and 2.03 V@5.0 A cm-2 at 80 °C, and unprecedented durability >1500 h@2.0 A cm-2. Thus, the dual engineering of inner multicomponent coordination environments and surface functional groups overcomes the activity-stability dilemma in the PEMWEs.

Aqueous Zn batteries hold great promise for large‐scale energy storage due to their high energy density, safety, and cost‐effectiveness. Electrolyte composition directly affects Zn anode stability, and additive engineering is an attractive and cost‐efficient strategy to suppress dendrite growth and inhibit side reactions. Unlike conventional single‐component additive strategies that offer limited effectiveness and targeted control, this work presents a novel synergistic dual‐additive (SDA) strategy that collaboratively modulates the electrical double layer (EDL). The fine‐tuning of hydrophobicity enables molecules to function as either water repellents or hydrogen bond disruptors, granting them the ability to selectively modify either the inner or the outer Helmholtz plane, together achieving a complementary reshape of the EDL. Through theoretical calculations and characterizations, it is revealed that SDA effectively suppresses side reactions at the Zn‐electrolyte interface, enabling uniform Zn deposition and minimizing the impact of additives on Zn reaction kinetics and electrolyte cost. This synergistic strategy enables a Zn anode lifespan exceeding 2000 h, and an ultra‐high areal capacity of 50 mAh cm −2 . Consequently, the anode‐free Zn‐Br batteries optimized by SDA demonstrate over 3000 stable cycles and achieve Ah‐level cells with a high energy density of 91 Wh kg −1 , paving the way for practical Zn‐based energy storage solutions.

The solid-electrolyte interphase (SEI) strongly determines the stability and reversibility of aqueous Zn-ion batteries (AZIBs). In traditional electrolytes, the nonuniform SEI layer induced by severe parasitic reactions, such as the hydrogen evolution reaction (HER), will exacerbate the side reactions on Zn anodes, thus leading to low zinc utilization ratios (ZURs). Herein, we propose to use methoxy ethylamine (MOEA) as a nucleophilic additive, which has a stronger nucleophilic characteristic than water, with the advantage of an abundance of nucleophilic atoms. The Helmholtz plane (HP) on the Zn anode can be manipulated via the adsorption of MOEA, which excludes free water from the HP due to its strong affinity with metallic Zn. Benefiting from the optimization of the HP, side reactions are greatly suppressed, and a smooth SEI layer can be constructed, enabling the Zn anode to work at high ZURs and high areal capacities. Consequently, the Zn||Cu asymmetric cell exhibits an extremely high cumulative plating capacity of 4 Ah cm-2 at 10 mA cm-2 with an average Coulombic efficiency (CE) of 99.8%. The Zn||Zn symmetric cell achieves a maximum ZUR of 80% at an areal capacity of 20 mAh cm-2 for 130 h, accounting for the boosted reversibility of Zn||V2O5 and Zn||AC full cells under low N/P ratios. Our strategy with nucleophilic electrolyte additives opens a path for developing durable aqueous Zn batteries with high ZURs.

Aqueous zinc-ion batteries attract widespread interest from researchers due to their inherent high safety, simple manufacturing, and low cost, making them favorable candidates for emerging electrochemical energy storage technologies. However, a series of issues faced by aqueous zinc (Zn) metal anodes hinders the development of high-performance aqueous Zn-ion batteries. In this review, we summarize the advantages of Zn metal anodes in weakly acidic electrolytes and analyze the causes and consequences of issues such as dendrite growth, corrosion, hydrogen evolution and low utilization rates faced by Zn metal anodes in detail. Additionally, we review the latest research findings on aqueous Zn metal anodes from various aspects, including Zn anode structural design, the construction of artificial interfacial layers, novel separators, and electrolyte optimization, while also analyzing the challenges encountered by these strategies. Finally, we systematically anticipate the future development directions of aqueous Zn metal anodes, aiming to accelerate the advancement of practical, highperformance aqueous Zn metal anodes.

Rechargeable aqueous zinc‐ion batteries are a promising solution for safe, cost‐effective, and sustainable energy storage. However, their widespread adoption is thwarted by challenges, such as dendrite formation, hydrogen evolution, and corrosion of Zn anode. Herein, a low‐cost and eco‐friendly p‐type high‐work‐function semiconducting artificial layer (HWF‐SAL) is designed on Zn anode, achieving desirable electrochemical performance for durable Zn anode. HWF‐SAL initially forms a Schottky barrier with Zn, which impedes electron transfer to the electrolyte and thereby suppresses hydrogen evolution. Additionally, in situ formation of CuZn alloy during cycling modulates the interfacial electronic nature, effectively curtailing the Schottky barrier and inducing an ohmic contact. This facilitates spontaneous electron accumulation at the Zn/HWF‐SAL interface, thereby guiding dendrite‐free Zn deposition, alleviating Zn corrosion, and improving Zn anode stability. As a result, HWF‐SAL symmetric cells manifest stable Zn plating/stripping reversibility over 3500 h while HWF‐SAL/Cu asymmetric cells exhibit an impressive average Coulombic efficiency (ACE) of 99.70% over 1150 cycles at 0.5 mA cm −2 /0.5 mAh cm −2 . Furthermore, the HWF‐SAL/NVO full cell delivers a high specific capacity of ≈300 mAh g −1 , retaining 82% capacity after 600 cycles, along with an ACE of 99.98%. These findings offer a practical pathway toward high‐performance aqueous Zn‐ion batteries.

Uncontrollable dendrite growth can jeopardize the cycle life of aqueous Zn batteries. Here, we propose a general strategy of engineering artificial protrusions (APs) on the electrode surface to regulate the distribution of the electrode interface electric field and induce stable Zn plating/stripping for Zn batteries. The junction-free AP-Cu network is constructed on Cu foil by an ultrafast Joule-heating-welding method. COMSOL simulation reveals that a stronger microelectric field is formed around the individual AP, which can effectively regulate a uniform nucleation of Zn on the AP-Cu network. Guided by the structural advantages of the AP design, the AP-Cu∥Zn cell delivers an average Coulombic efficiency (CE) of 99.85% at 2 C with an areal capacity of 1.77 mAh cm-2 for over 3000 cycles. Moreover, the AP design enables stable cycling of both Zn|AP-Cu∥V2O5 and anode-free AP-Cu∥Br2 full cells, providing a promising strategy for the development of high-performance energy storage devices.

Owing to their high volumetric capacity, reasonably low redox potential, and budget friendliness, manganese metal batteries (MnMBs) are excellent candidates for batteries with a high energy -to -price ratio. However, since there is no suitable electrolyte ensuring reversible Mn plating/stripping due to the low redox potential of the Mn 2+ /Mn redox couple and the strong interaction between charge -dense Mn 2+ ions and solvents, the development of MnMBs has been largely constrained. Herein, a halogen -mediated non -aqueous electrolyte (HM-NAE) is developed to enable highly reversible Mn plating/stripping. Benefiting from this halogen -mediated mechanism, the asymmetric Mn cell can cycle stably more than 1,000 h with a Coulombic efficiency close to 100%. Moreover, a Mn|HM-NAE|Mo 6 S 8 full cell with high electrochemical performances is constructed and fully understood. This work offers a new avenue to the development of rechargeable, non -aqueous MnMB through electrolyte engineering, which can also shed light on other multivalent metal batteries and electroplating industry.