Dual-coordination electrolyte additive to achieve high energy density 4-electron aqueous zinc iodine battery.

Polyaniline/nitrogen-doped hollow fiber for high performance zinc-iodine batteries

ABSTRACT Aqueous zinc–iodine batteries (AZIBs) possess significant potential for energy storage owing to their high theoretical capacity and remarkable cycling stability. Nevertheless, their practical deployment is severely constrained by a shortened life resulting from uncontrollable parasitic reactions and poor temperature adaptability. Herein, we design a multifunctional dual‐network hydrogel electrolyte PHEAA‐CMC‐ Zn(CF 3 SO 3 ) 2 (HCZ) composed of rigid carboxymethyl cellulose (CMC) and flexible poly (N‐hydroxyethyl acrylamide) (PHEAA) featuring abundant dynamic intra/intermolecular hydrogen bonds. Intriguingly, the rich hydrophilic groups in the electrolyte form hydrogen bonds with water molecules, effectively regulating water‐induced side reactions at the electrode–electrolyte interfaces and enabling excellent temperature tolerance across a wide range from −30°C to 50°C. Moreover, the polar amide groups and oxygen‐containing functionalities within the hydrogel can coordinate with Zn 2+ to promote Zn 2+ migration at the anode, while simultaneously providing electrostatic adsorption of polyiodide species to mitigate the shuttle effect at the cathode. Therefore, Zn‖Zn symmetric cells equipped with this engineered electrolyte exhibit prolonged cycling stability exceeding 3000 h at both 20 and −30°C. Moreover, AZIBs with this hydrogel deliver long‐term cycling durability over 20 000 cycles at −30°C and 30 000 cycles at 50°C. This electrolyte provides new insights for AZIBs capable of stable operation across broad temperature.

Aqueous zinc-iodine (Zn-I2) batteries, owing to their compelling combination of environmental friendliness, cost-effectiveness, and enhanced safety features, are regarded as promising candidates for large-scale energy storage systems. Nevertheless, the limited I2/2I- two-electron redox chemistry and nonuniform Zn deposition critically impair the energy density and cycling stability of aqueous Zn-I2 batteries, hindering their practical deployment. Herein, multifunctional cyclohexylamine hydrochloride (CHAH) additive is introduced into the ZnSO4 electrolyte, which synergistically enables a dendrite-free Zn anode for extended cyclability and simultaneously activates a stable four-electron 2I+/I2/2I- redox chemistry at the I2 cathode. Combined experimental characterization and theoretical calculations reveal that the cyclohexylamine (CHA) reconstructs the Zn2+ solvation structure by displacing active H2O, while fostering a nitrogen-rich solid electrolyte interphase on the Zn anode at the same time. It suppresses parasitic reactions and enables excellent Zn plating/stripping cycling for 2150 h at 1 mA cm-2/1 mAh cm-2. Furthermore, nucleophilic amine groups in CHA act synergistically with Cl- to coordinate I+ by forming (2CHA)ICl, which improves four-electron 2I+/I2/2I- redox kinetics and achieves exceptional Zn-I2 battery performances (256.3 mAh g-1 at 10 A g-1). This bilateral nitrogen interface chemistry mechanism offers key insights into the development of high-performance Zn-I2 batteries.

Aqueous zinc-iodine batteries (ZIBs) are a promising energy storage technology due to the abundance of iodine, environmental friendliness, and low cost. This study introduces a multifunctional additive, l-lysine hydrochloride (LLH), designed to activate the four-electron transfer chemistry between I+ and I- species, significantly boosting energy density. LLH stabilizes I+ via dual coordination from the amino groups and chloride ion, effectively suppressing hydrolysis and enabling reversible 2I-/I0 2/2I+ conversion. The preferential adsorption of the carboxyl group of protonated l-lysine at the zinc anode promotes uniform zinc deposition while inhibiting the hydrogen evolution reaction. Additionally, the incorporation of LLH effectively suppresses the shuttle effect by interacting with iodine species through its carboxyl and amino groups. LLH-modified Zn‖Zn symmetric batteries demonstrate extended cycling stability, operating beyond 4000 hours, while Zn‖I2 full batteries deliver a high specific capacity of 502 mAh g-1 at 1 A g-1. This additive strategy renders a facile and efficient approach to realizing high-capacity and durable ZIBs.

A trifunctional electrolyte-separator system for high-performance aqueous zinc-iodine batteries across a wide temperature range

Aqueous zinc-iodine batteries are promising contenders for next-generation grid-scale energy storage batteries. However, their deployment is hindered by zinc anode degradation at moderate cycling rates (0.5-2 C), including dendrite growth and parasitic hydrogen evolution reaction (HER), stemming from an unstable Zn/electrolyte interphase. Herein, a sugar alcohol-based multifunctional additive of mannitol (ML), identified via theoretical screening based on molecular characteristics of electrostatic polarity, H2O binding energy, and LUMO level, is proposed to achieve comprehensive Zn/electrolyte interphase stabilization from the bulk phase to the inner Helmholtz plane (IHP). Leveraging abundant hydroxyl groups and good Zn2+ affinity, ML disrupts the bulk hydrogen-bond network and reconstructs Zn2+ solvation structure, simultaneously suppressing proton-hopping pathways and accelerating Zn2+ desolvation. Moreover, robust chemisorption of ML molecules on both Zn (002) and Zn (101) planes modulates Zn deposition toward the thermodynamically stable (002) texture with enlarged grain size, thereby enabling dendrite-free plating. Benefiting from these synergistic effects, Zn||I2 full cells achieve an ultrahigh areal capacity of 6.5mAhcm-2 over 3000 cycles at a practical rate of 1 C. Multiple Ah-level Zn||I2 pouch cells are also demonstrated, sustaining 1000 cycles with only 0.02% capacity decay per cycle, underscoring strong prospects for practical large-scale application.

Aqueous zinc-iodine batteries (AZIBs) leveraging four-electron I-/I0/I+ redox chemistry show great promise in safe energy storage systems. However, realizing Ah-level AZIBs with industrial-grade parameters (≥10 mg cm-2 mass loading) remains fundamentally challenging. Here, we prepare the hydrogel electrolyte with mesoporous nanoparticles SBA-15 (MNPHE) by a nanoconfined polymerization strategy. The framework confinement effect, anion confinement effect, and free water confinement effect are achieved through Lewis acid-base interactions and hydrogen bond networks. The multiconfinement effects yield simultaneous ultrahigh mechanical strength (501 kPa tensile strength) and a record-high Zn2+ transference number (tZn2+ = 0.95), which collectively suppressed polyiodide generation and I+ species hydrolysis. This results in markedly enhanced reversibility and kinetics for four-electron I-/I0/I+ redox chemistry under a high-I2-mass-loading cathode. Based on MNPHE, the Zn||I2 full cells display a record-low self-discharge rate with only 20% capacity loss after three months and a prolonged lifetime of 100,000 cycles at 25 C. Furthermore, Ah-level four-electron Zn||I2 pouch cells achieve excellent cyclability of 800 cycles and an ultrahigh cathode-mass-specific energy density of 466.7 Wh kg-1, surpassing all aqueous Zn-based systems in the Ah-level regime.

Aqueous zinc-iodine (Zn─I2) batteries demonstrate immense potential for energy storage owing to their inherent safety, stable voltage plateau, and environmental friendliness. However, the slow iodine conversion, polyiodide shuttle effect, and uncontrollable Zn dendrites impede the improvement of their performance. Herein, we successfully designed a bifunctional core-shell host derived from BiHCF@ZIF-8, which consists of a porous carbon matrix encapsulating abundant metal catalytic sites and trace N-doping (BZPC). This superior multi-site co-doped hierarchical porous structure can serve as a high-efficiency iodine carrier to effectively confine iodine species and enhance their conversion kinetics. Simultaneously, the BZPC can also be applied as a functional modification layer to induce uniform Zn deposition, thereby achieving a dendrite-free Zn anode. The assembled Zn//BZPC@I2 batteries and BZPC@Zn symmetric cells can operate stably at ultrahigh current densities of 50C and 100mAcm-2, respectively. Through a synergistic optimization strategy of "one host for dual purposes", the BZPC@Zn//BZPC@I2 batteries achieve an ultralong lifespan of 28000 stable cycles even at an ultrahigh current density of 50C. This study not only pioneers the difunctional BZPC for both iodine host design and zinc interface engineering but also establishes an innovative and scalable strategy for developing long-life and high-rate Zn─I2 batteries.

Suppressing the shuttle effect in zinc-iodine batteries via ordered microporous carbon nanospheres from a one-step strategy

Integrated confinement-chemisorption-catalysis cathode for highly stable zinc-iodine batteries

ABSTRACT Zn–I 2 batteries is a promising large‐scale energy storage technology, yet conventional Zn metal anode faces challenges including corrosion, dendrite growth, and side reactions, hindering its practical application. Zn 2+ host anodes, leveraging the rocking‐chair mechanism and inherent polyiodide inertness, offer a potential solution to these issues. However, existing host anodes suffer from sluggish Zn 2+ kinetics and low capacity, limiting their compatibility with cathodes. Herein, we report a unique charge and lattice self‐regulation mechanism in Cu 3 PSe 4 that drives expedited Zn 2+ transport and high‐capacity performance. In this configuration, Cu 3 PSe 4 in situ decomposes to P and Cu 2 Se during initial cycling and Cu 2 Se provide subsequent capacity. Importantly, phosphorus modulates the Cu 2 Se lattice, inducing a transition from conventional contraction to expansion during Zn 2+ insertion, thereby enhancing ion transport kinetics and capacity simultaneously. Theoretical calculations reveal that P reconfigures the charge distribution and spatial configuration in Cu 2 Se, reducing Zn 2+ diffusion barrier. Consequently, the optimized Cu 3 PSe 4 anode delivers 150.5 mAh g −1 at 20 A g −1 , and the assembled Cu 3 PSe 4 ||I 2 cell achieves an exceptional lifespan of 30,000 cycles at 9 mg cm −2 with a low N/P ratio of 1.1, demonstrating superior stability. This work provides a novel system of corrosion‐resistant anode for high‐performance and metal‐zinc‐free zinc–iodine batteries.

Rational engineering of the local microenvironment in catalytic host materials is pivotal for high-performance zinc-iodine batteries, as it governs iodine species adsorption, accelerates redox kinetics, and suppresses polyiodides shuttling. Herein, we propose a local polarity engineering strategy by incorporating unsaturated Cu-N3 sites into carbon matrix to construct polarized microenvironments and promote iodine redox chemistry. Combined theoretical and experimental analyses reveal that the unsaturated coordination of Cu atoms induces intrinsic local polarity, which enhances charge redistribution, lowers the activation barrier of the I2/I- redox reaction, and strengthens electronic coupling with polyiodide intermediates. In situ UV-vis and Raman spectroscopies corroborate that the Cu-N3 sites effectively immobilize polyiodides, thus mitigating the shuttle effect. As cathode host, the Cu-N3 sites-rich carbon electrode achieves high discharge capacity of 232.2 mAh g-1 at 0.2 A g-1 and exceptional long-term stability with 94.02% capacity retention after 50,000 cycles at 10 A g-1. More importantly, benefiting from its superior catalytic activity toward iodine redox reaction, the Cu-N3 sites-rich carbon enables solar cells to achieve a remarkable power conversion efficiency of 9.14%. This work elucidates a novel design principle for regulating local polarity to propel iodine electrochemistry, offering new insights into the development of advanced iodine-based energy devices.

Flexible aqueous zinc-iodine batteries (AZIBs) have emerged as promising candidates for the power source in wearable electronics, owing to their intrinsic safety and cost-effectiveness. However, electrochemical and mechanical interface instability between zinc anodes and electrolytes under deformation prevent the reliable performance of AZIBs in practical applications. Here, we present a synergistic supramolecular interactions engineering strategy utilizing hydrogen bonding, ion-dipole, and coordination interactions to enhance interfacial stability by creating a polyacrylamide-trehalose- dimethylglycine (PATT) hydrogel electrolyte with strengthened interfacial adhesion, reduced water activity, and facilitated ion transport. With PATT, Zn||ZnI2 cell delivers an areal capacity of 4.2 mAh cm- 2 with 85.2% retention after 6000 h, while multilayer pouch cell maintains 1.2 Ah with 92.3% retention over 175 cycles. Excellent mechanical resilience and electrochemical stability of Zn||ZnI2 cells are further observed under successive loading cycles of bending and stretching. The strain-sensing capability of PATT hydrogel is also investigated, thereby enabling the energy supply and hand motion capture with monolithic material. A smart glove for virtual reality interaction is demonstrated to highlight the potential of PATT hydrogel in achieving mechanical-robust wearable electronics.

Zn-I2 batteries is a promising large-scale energy storage technology, yet conventional Zn metal anode faces challenges including corrosion, dendrite growth, and side reactions, hindering its practical application. Zn2+ host anodes, leveraging the rocking-chair mechanism and inherent polyiodide inertness, offer a potential solution to these issues. However, existing host anodes suffer from sluggish Zn2+ kinetics and low capacity, limiting their compatibility with cathodes. Herein, we report a unique charge and lattice self-regulation mechanism in Cu3PSe4 that drives expedited Zn2+ transport and high-capacity performance. In this configuration, Cu3PSe4 in situ decomposes to P and Cu2Se during initial cycling and Cu2Se provide subsequent capacity. Importantly, phosphorus modulates the Cu2Se lattice, inducing a transition from conventional contraction to expansion during Zn2+ insertion, thereby enhancing ion transport kinetics and capacity simultaneously. Theoretical calculations reveal that P reconfigures the charge distribution and spatial configuration in Cu2Se, reducing Zn2+ diffusion barrier. Consequently, the optimized Cu3PSe4 anode delivers 150.5 mAh g-1 at 20 A g-1, and the assembled Cu3PSe4||I2 cell achieves an exceptional lifespan of 30,000 cycles at 9mg cm-2 with a low N/P ratio of 1.1, demonstrating superior stability. This work provides a novel system of corrosion-resistant anode for high-performance and metal-zinc-free zinc-iodine batteries.

The development of static aqueous zinc-iodine batteries (SAZIBs) is hindered by the polyiodide shuttling effect and poor zinc anode reversibility, issues that are exacerbated under high iodine loadings essential for high energy density. Herein, a gradient-structured separator (G-CCN@GF) is designed by modifying a glass fiber separator with 2D cyano-functionalized graphitic carbon nitride (CCN). Experimental and simulation results demonstrate that the dense CCN layer facing the cathode effectively anchors polyiodides and unlocks latent electrochemical active sites, thereby facilitating conversion kinetics under high iodine loading and I/C ratio. Meanwhile, the thin and uniform CCN layer on the anode side promotes a uniform Zn2+ flux, significantly improving the zinc reversibility under high depth of discharge (DOD). Consequently, the Zn/G-CCN@GF/I2 battery with a conventional activated carbon (AC) host achieves exceptional performance under high I/C ratio (2:1) conditions, including a high areal capacity of 27.9 mAh cm-2 at 150.1mg cm-2 iodine loading and remarkable stability over 7200 cycles at 40mg cm-2. A 60 cm2 pouch cell further validates practicality, delivering 5.8 mAh cm-2 and retaining 85.87% capacity after 1100 cycles. This work provides a feasible separator-engineering strategy for high-energy-density SAZIBs.

Aqueous zinc-iodine batteries (AZIBs) are intrinsically safe and cost-effective, yet their performance is limited by sluggish iodine redox kinetics, poor conductivity, and severe polyiodide shuttling. Herein, we design a heterostructure cathode by depositing titanium nitride (TiN) onto biomass-derived porous nitrogen-doped carbon (PNC), forming a tailored PNC@TiN interface that markedly enhances electronic conductivity and regulates iodine electrochemistry. Density functional theory (DFT) calculations reveal pronounced interfacial charge redistribution with an upward shift of the Ti d-band centeri, enabling strong Ti─I bonding through orbital coupling among Ti 3d, C/N 2p, and I 5p states, as well as improved iodine affinity with suppressed polyiodide shuttle. Accordingly, the AZIB with the PNC@TiN cathode exhibits a high reversible capacity of 166.9mAhg-1 after 21,000 cycles at 2.0Ag-1 (95.4% retention), and exceptional durability over 66,000 cycles at 5.0Ag-1 with an ultralow capacity decay of 0.00028% per cycle. Furthermore, the as-assembled pouch cells achieve 176.1mAhg-1 with negligible degradation, highlighting their practical viability. This work underscores the crucial role of interfacial electronic nanoarchitectonics in modulating iodine chemistry, and presents a sustainable strategy to repurpose biomass into advanced energy-storage materials.

Aqueous zinc-iodine (Zn-I2) batteries, despite their cost-effectiveness and safety, are plagued by zinc anode corrosion and the polyiodide shuttle effect. Herein, trace tetraethylenepentamine (TEP), with a high-density N-H proton array, is employed to regulate the running environment of Zn-I2 batteries, which suppresses anode corrosion and polyiodide formation, enabling long-term cycling under high-loading conditions. For the zinc anode, TEP's high-density N-H array facilitates preferential surface adsorption, optimizing the interfacial Helmholtz layer. Rich in lone-pair electrons, its -NH2 and -NH- groups as Lewis bases coordinate with Zn2+ ions to regulate interfacial ion dynamics, enabling dendrite-free Zn deposition. For the iodine cathode, TEP coordinates with I2 via the lone pair electrons of N atoms and forms strong electrostatic hydrogen bonds between H protons and I-, synergistically suppressing polyiodides formation, thereby enhancing the utilization of the iodine cathode. Consequently, TEP enables the Zn||Zn battery to achieve a stable cycling for over 2333h (1mA cm-2, 1 mAh cm-2). The Zn-I2 battery with a high iodine loading (15.9mg cm-2) retains 91.3% capacity after 8900 cycles. This study demonstrates that incorporating a trace amount of TEP provides a new insight into the development of sustainable, long-life Zn-I2 batteries.

Aqueous zinc–iodine batteries (Zn–I 2 Bs) emerge as promising candidates for grid‐scale energy storage due to their inherent safety, low cost, and environmental benignity. However, their practical deployment is hindered by critical challenges, including severe self‐discharge driven by coupled polyiodide shutting and hydrogen evolution reaction (HER), limited practical energy density constrained by low voltage plateaus and predominantly two‐electron iodine redox, sluggish reaction kinetics from complex iodine species interconversion, and zinc anode instability (dendrites, corrosion, passivation). This work provides a comprehensive analysis of Zn–I 2 B mechanisms, debating the interplay between iodine's layered structure favoring intercalation and its multivalency enabling conversion reactions, particularly pathways for electron redox beyond I − /I 2 . Strategies to mitigate these challenges are critically reviewed: anchoring iodine species within tailored host materials (e.g., functionalized carbons, COFs, perovskites) to suppress shuttling; electrolyte engineering (e.g., DES, additives) to sequester free I − and modulate solvation; functional separators/membranes for ion sieving; catalytic materials (transition metal/nonmetal‐based) to accelerate kinetics; and anode protection/modification (interfacial layers, hydrogel electrolytes, nonmetallic anodes) to enhance reversibility. The review synthesizes recent advances, identifies persistent bottlenecks, and outlines future research directions essential for realizing the commercial potential of high‐performance Zn–I 2 Bs.

Aqueous zinc-iodine batteries (ZIBs) have attracted extensive attention due to their advantages of high theoretical specific capacity, abundant reserves, high safety, and low cost, while the Zn anodes are still suffering from dendrite growth, side reactions, and polyiodide corrosion, seriously affecting the service life of ZIBs. Herein, sulfonated cellulose acetate (SCA) nanofiber membrane with zincophilic-hydrophobic property is constructed on the Zn anode as a protective layer by electrospinning to circumvent the above problems and achieve a stable Zn anode. Attributing to both the hydrophobicity and zincophilicity, the SCA nanofiber membrane not only reduces the activity of water but also promotes the Zn2+ desolvation. Moreover, negatively-charged groups of the SCA nanofiber membrane cause electrostatic repulsion with polyiodide. Density functional theory calculations and COMSOL simulations further reveal that the SCA nanofiber membrane can tune the uniform 3D deposition behavior of Zn2+ by chemisorption and physical structure, respectively. The obtained ZIBs can achieve ultra-long life span (>13000 cycles) with high-capacity retention (96.74%) and reversibility (average CE: 99.83%), demonstrating the reliability of our proposed strategy for achieving stable and high-performance ZIBs.