Pyrrolic-Nitrogen Chemistry in 1-(2-hydroxyethyl)imidazole Electrolyte Additives toward a 50,000-Cycle-Life Aqueous Zinc-Iodine Battery.

Rechargeable aqueous zinc iodine (Zn-I2) batteries offer benefits such as low cost and high safety. Nevertheless, their commercial application is hindered by hydrogen evolution reaction (HER) and polyiodide shuttle, which result in a short lifespan. In this study, 1-(2-hydroxyethyl)imidazole (HEI) organic molecules featuring pyrrole-N groups are introduced as dually-functional electrolyte additives to simultaneously stabilize Zn anode and confine polyiodide through ion-dipole interactions. The pyrrole-N groups in HEI can preserve the interfacial pH equilibrium at Zn anode by reversibly capturing H+ ions and dynamically neutralizing OH- ions, thereby suppressing the HER. Notably, the H2 evolution rate at the Zn anode is reduced to a mere 2.20 µmol h-1 cm-2. Furthermore, the pyrrole-N moieties in HEI effectively curtail the polyiodide shuttle at I2 cathode, which show adsorption energies of -0.174 eV for I2, -0.521 eV for I3-, and -0.768 eV for I-, as indicated by density functional theory calculations. Electrochemical testing demonstrates that the Zn//Zn symmetric cell maintains stable cycling for up to 4,200 hours at 1 mA cm-2. Most strikingly, at a high I2 mass loading of 9.7 mg cm-2, the Zn-I2 battery achieves an extraordinary cycle life of 50,000 cycles.

Molecular Bridging Induced Anti-salting-out Effect Enabling High Ionic Conductive ZnSO4-based Hydrogel for Quasi-solid-state Zinc Ion Batteries.

Hydrogel electrolytes (HEs) hold great promise in tackling severe issues emerging in aqueous zinc-ion batteries, but the prevalent salting-out effect of kosmotropic salt causes low ionic conductivity and electrochemical instability. Herein, a subtle molecular bridging strategy is proposed to enhance the compatibility between PVA and ZnSO4 from the perspective of hydrogen-bonding microenvironment re-construction. By introducing urea containing both an H-bond acceptor and donor, the broken H-bonds between PVA and H2O, initiated by the SO42--driven H2O polarization, could be re-united via intense intermolecular hydrogen bonds, thus leading to greatly increased carrying capacity of ZnSO4. The urea-modified PVA-ZnSO4 HEs featuring a high ionic conductivity up to 31.2 mS cm-1 successfully solves the sluggish ionic transport dilemma at the solid-solid interface. Moreover, an organic solid-electrolyte-interphase can be derived from the in-situ electro-polymerization of urea to prohibit H2O-involved side reactions, thereby prominently improving the reversibility of Zn chemistry. Consequently, Zn anodes witness an impressive lifespan extension from 50 h to 2200 h at 0.1 mA cm-2 while the Zn-I2 full battery maintains a remarkable Coulombic efficiency (>99.7%) even after 8000 cycles. The anti-salting-out strategy proposed in this work provides an insightful concept for addressing the phase separation issue of functional HEs.

Interfacial Protection Engineering of Sodium Nanoparticles toward Dendrite-Free and Long-Life Sodium Metal Battery.

The instability of interfacial solid-electrolyte interphase (SEI) layer of metallic sodium (Na) anode during cycles results in the rapid capacity decay of sodium metal batteries (SMBs). Herein, the concept of interfacial protection engineering of Na nanoparticles (Na-NPs) is proposed first to achieve stable, dendrite-free, and long-life SMB. Employing an ion-exchange strategy, conformal Sn-Na alloy-SEI on the interface of Na-NPs is constructed, forming Sn@Na-NPs. The stable alloy-based SEI layer possesses the following three advantages: 1) significantly enhancing the transport dynamics of Na+ ions and electrons; 2) enabling the well-distributed deposition of Na+ ions to avoid the growth of dendrites; and 3) protecting the Sn@Na-NPs anode from the attack of electrolyte, thereby reducing the parasitic reaction and boosting the Coulombic efficiency of SMBs. Because of these virtues, the symmetric Sn@Na-NPs cell shows an ultralow voltage hysteresis of 0.54 V at 10 mA cm-2 after 600 h. Paired with the Na3 V2 (PO4 )2 O2 F (NaVPF) cathode, the NaVPF-Sn@Na-NPs full cell exhibits an initial discharge capacity of 89.2 mAh g-1 at 1 C and a high capacity retention of 81.6% after 600 cycles.

Weakening the Space Charge Layer Effect Through Tethered Anion Electrolyte and Piezoelectric Effect Toward Ultra-Stable Zinc Anode.

The space charge layer (SCL) dilemma, caused by mobile anion concentration gradient and the rapid consumption of cations, is the fundamental reason for the generation of zinc dendrites, especially under high-rate discharge conditions. To address the issue, a physical (PbTiO3)/chemical (AMPS-Zn) barrier is designed to construct stable zinc ion flow and disrupt the gradient of anion concentration by coupling the ferroelectric effect with tethered anion electrolyte. The ferroelectric materials PbTiO3 with extreme-high piezoelectric constant can spontaneously generate an internal electric field to accelerate the movement of zinc ions, and the polyanionic polymer AMPS-Zn can repel mobile anions and disrupt the anions concentration gradient by tethering anions. Through numerical simulations and analyses, it is discovered that a high Zn2+ transference number can effectively weaken the SCL, thus suppressing the occurrence of zinc dendrites and parasitic side reactions. Consequently, an asymmetric cell using the PbTiO3@Zn demonstrates a reversible plating/stripping performance for 2900 h, and an asymmetric cell reaches a state-of-the-art runtime of 3450 h with a high average Coulombic efficiency of 99.98%. Furthermore, the PbTiO3@Zn/I2 battery demonstrated an impressive capacity retention rate of 84.0% over 65000 cycles by employing a slender Zn anode.

High-Entropy Transition Metal Phosphorus Trichalcogenides for Rapid Sodium Ion Diffusion.

High-entropy strategies are regarded as a powerful means to enhance performance in energy storage fields. The improved properties are invariably ascribed to entropy stabilization or synergistic cocktail effect. Therefore, the manifested properties in such multicomponent materials are usually unpredictable. Elucidating the precise correlations between atomic structures and properties remains a challenge in high-entropy materials (HEMs). Herein, atomic-resolution scanning transmission electron microscopy annular dark field (STEM-ADF) imaging and four dimensions (4D)-STEM are combined to directly visualize atomic-scale structural and electric information in high-entropy FeMnNiVZnPS3. Aperiodic stacking is found in FeMnNiVZnPS3 accompanied by high-density strain soliton boundaries (SSBs). Theoretical calculation suggests that the formation of such structures is attributed to the imbalanced stress of distinct metal-sulfur bonds in FeMnNiVZnPS3. Interestingly, the electric field concentrates along the two sides of SSBs and gradually diminishes toward the two-dimensional (2D) plane to generate a unique electric field gradient, strongly promoting the ion-diffusion rate. Accordingly, high-entropy FeMnNiVZnPS3 demonstrates superior ion-diffusion coefficients of 10-9.7-10-8.3 cm2 s-1 and high-rate performance (311.5 mAh g-1 at 30 A g-1). This work provides an alternative way for the atomic-scale understanding and design of sophisticated HEMs, paving the way for property engineering in multi-component materials.

Crowding Effect-Induced Zinc-Enriched/Water-Lean Polymer Interfacial Layer Toward Practical Zn-Iodine Batteries.

Although the meticulous design of functional diversity within the polymer interfacial layer holds paramount significance in mitigating the challenges associated with hydrogen evolution reactions and dendrite growth in zinc anodes, this pursuit remains a formidable task. Here, a large-scale producible zinc-enriched/water-lean polymer interfacial layer, derived from carboxymethyl chitosan (CCS), is constructed on zinc anodes by integration of electrodeposition and a targeted complexation strategy for highly reversible Zn plating/stripping chemistry. Zinc ions-induced crowding effect between CCS skeleton creates a strong hydrogen bonding environment and squeezes the moving space for water/anion counterparts, therefore greatly reducing the number of active water molecules and alleviating cathodic I3- attack. Moreover, the as-constructed Zn2+-enriched layer substantially facilitate rapid Zn2+ migration through the NH2-Zn2+-NH2 binding/dissociation mode of CCS molecule chain. Consequently, the large-format Zn symmetry cell (9 cm2) with a Zn-CCS electrode demonstrates excellent cycling stability over 1100 h without bulging. When coupled with an I2 cathode, the assembled Zn-I2 multilayer pouch cell displays an exceptionally high capacity of 140 mAh and superior long-term cycle performance of 400 cycles. This work provides a universal strategy to prepare large-scale production and high-performance polymer crowding layer for metal anode-based battery, analogous outcomes were veritably observed on other metals (Al, Cu, Sn).