Act in contravention: a non-planar coupled electrode design utilizing "tip effect" for ultra-high areal capacity, long cycle life zinc-based batteries

A Choline-Based Antifreezing Complexing Agent with Selective Compatibility for Zn-Br2 Flow Batteries

The high freezing point of polybromides, charging products, is a significant obstacle to the rapid development of zinc-bromine flow batteries (Zn-Br2 FBs). Here, a choline-based complexing agent (CCA) is constructed to liquefy the polybromides at low temperatures. Depending on quaternary ammonium group, choline can effectively complex with polybromide anions and form dense oil-phase that has excellent antifreezing property. Benefiting from indispensable strong ion-ion interaction, the highly selectively compatible CCA, consisting of choline and N-methyl-N-ethyl-morpholinium salts (CCA-M), can be achieved to further enhance bromine fixing ability. Interestingly, the formed polybromides with CCA-M are able to keep liquid even at -40 °C. The CCA-M endows Zn-Br2 FBs at 40 mA cm-2 with unprecedented long cycle life (over 150 cycles) and high Coulombic efficiency (CE, average ≈98.8%) at -20 °C, but also at room temperature (over 1200 cycles, average CE: ≈94.7%). The CCA shows a promising prospect of application and should be extended to other antifreezing bromine-based energy storage systems.

Molecular recognition effect enabled by novel crown ether as macrocyclic host towards highly reversible Zn anode

Aqueous Zn2+ ion batteries present notable advantages, including high abundance, low toxicity, and intrinsic nonflammability. However, they exhibit severe irreversibility due to uncontrolled dendrite growth and corrosion reactions, which limit their practical applications. Inspired by their distinct molecular recognition characteristics, supramolecular crown ethers featuring interior cavity sizes identical to the diameter of Zn2+ ions were screened as macrocyclic hosts to optimize the Zn2+ coordination environment, facilitating the suppression of the reactivity of H2O molecules and inducing the in-situ formation of organic-inorganic hybrid dual-protective interphase. The in-situ assembled interphase confers the system with an "ion-sieving" effect to repel H2O molecules and facilitate rapid Zn2+ transport, enabling the suppression of side reactions and uniform deposition of Zn2+ ions. Consequently, we were able to achieve dendrite-free Zn2+ plating/stripping at 98.4% Coulombic efficiency for approximately 300 cycles in Zn||Cu cell, steady charge-discharge for 1360 h in Zn||Zn symmetric cell, and improved cyclability of 70% retention for 200 cycles in Zn||LMO full cell, outlining a promising strategy to challenge lithium-ion batteries in low-cost, and large-scale applications.

Electrode Materials for Enhancing the Performance and Cycling Stability of Zinc Iodide Flow Batteries at High Current Densities

Aqueous redox flow battery systems that use a zinc negative electrode have a relatively high energy density. However, high current densities can lead to zinc dendrite growth and electrode polarization, which limit the battery's high power density and cyclability. In this study, a perforated copper foil with a high electrical conductivity was used on the negative side, combined with an electrocatalyst on the positive electrode in a zinc iodide flow battery. A significant improvement in the energy efficiency (ca. 10% vs using graphite felt on both sides) and cycling stability at a high current density of 40 mA cm^-2 was observed. A long cycling stability with a high areal capacity of 222 mA h cm^-2 is obtained in this study, which is the highest reported areal capacity for zinc-iodide aqueous flow batteries operating at high current density, in comparison to previous studies. Additionally, the use of a perforated copper foil anode in combination with a novel flow mode was discovered to achieve consistent cycling at exceedingly high current densities of >100 mA cm^-2. In situ and ex situ characterization techniques, including in situ atomic force microscopy coupled with in situ optical microscopy and X-ray diffraction, are applied to clarify the relationship between zinc deposition morphology on the perforated copper foil and battery performance in two different flow field conditions. With a portion of the flow going through the perforations, a significantly more uniform and compact zinc deposition was observed compared to the case where all of the flow passed over the surface of the electrode. Results from modeling and simulation support the conclusion that the flow of a fraction of electrolyte through the electrode enhances mass transport, enabling a more compact deposit.

Printing 3D mesh-like grooves on zinc surface to enhance the stability of aqueous zinc ion batteries

Aqueous zinc ion batteries (AZIBs) are receiving broad attention owing to their high safety and low cost. However, the high mechanical strength and irreversible growth of zinc dendrites limit the practical application of AZIBs. Herein, regular mesh-like gullies are built on the surface of zinc foil (M150 Zn) by using simple model pressing method and stainless steel mesh as a mold. Due to the charge-enrichment effect, zinc ion deposition and stripping will be preferentially carried out in the grooves to keep the outer surface flat. In addition, zinc is exposed to 002 crystal surface in the gully after being pressed, and the deposited zinc is more inclined to grow at a small angle, so that it has a sedimentary morphology parallel to the basement. Consequently, at a current density of 0.5 mA cm^-2, the M150 zinc anode has a voltage hysteresis of only 35 mV and a cycle life of up to 400 h (relative to a zinc foil of 96 mV and 160 h). Even more imposing is that the full cell has a capacity retention of approximately 100% after 1000 cycles at 2 A g^-1 and a specific capacity of almost 60 mAh g^-1 when activated carbon is used as the cathode. It is a promising method to improve the stable cycle performance of AZIBs by using a simple method to realize the non-prominent dendrites on the surface of zinc electrode.

Challenges and Strategies in the Development of Zinc-Ion Batteries

Although promising, the practical use of zinc-ion batteries (ZIBs) remains plagued with uncontrollable dendrite growth, parasitic side reactions, and the high intercalation energy of divalent Zn²⁺ ions. Hence, much work has been conducted to alleviate these issues to maximize the energy density and cyclic life of the cell. In this holistic review, the mechanisms and rationale for the stated challenges shall be summarized, followed by the corresponding strategies employed to mitigate them. Thereafter, a perspective on present research and the outlook of ZIBs would be put forth in hopes to enhance their electrochemical properties in a multipronged approach.

An advanced Ca/Zn hybrid battery enabled by the dendrite-free zinc anode and a reversible calcification/decalcification NASICON cathode

The proposal of hybrid ion batteries, which can integrate the advantages of the single ion battery, opens up a new route for developing high-performance secondary batteries. Herein, we successfully constructed an aqueous hybrid battery comprised of polyanionic-type cathode material (Na3V2(PO4)3, NVP), Zn metal anode, and aqueous Ca2+/Zn2+ hybrid electrolyte. This exciting combination gives full play to not only the excellent diffusion dynamics of Ca2+ in the NASICON (sodium super ion conductors) structure but also the electrostatic shielding effect of Ca2+ with low reduction potential that inhibits the formation of zinc dendrites. As results, the NVP//Zn Zn/Ca hybrid battery delivers favorable specific capacity with outstanding rate performance (85.3 mAh g-1 capacity at 1 C, 60.5 mAh g-1 capacity at 20 C), and excellent cycle stability (74 % capacity retention after 1300 cycles).

Recent Advances of Aqueous Rechargeable Zinc-Iodine Batteries: Challenges, Solutions, and Prospects

Aqueous rechargeable zinc-iodine batteries (ZIBs), including zinc-iodine redox flow batteries and static ZIBs, are promising candidates for future grid-scale electrochemical energy storage. They are safe with great theoretical capacity, high energy, and power density. Nevertheless, to make aqueous rechargeable ZIBs practically feasible, there are quite a few hurdles that need to be overcome, including self-discharge, sluggish kinetics, low energy density, and instability of Zn metal anodes. This article first reviews the electrochemistry in aqueous rechargeable ZIBs, including the flow and static battery configurations and their electrode reactions. Then the authors discuss the fundamental questions of ZIBs and highlight the key strategies and recent accomplishments in tackling the challenges. Last, they share their thoughts on the future research development in aqueous rechargeable ZIBs.

Future Trends and Aging Analysis of Battery Energy Storage Systems for Electric Vehicles

The increase of electric vehicles (EVs), environmental concerns, energy preservation, battery selection, and characteristics have demonstrated the headway of EV development. It is known that the battery units require special considerations because of their nature of temperature sensitivity, aging effects, degradation, cost, and sustainability. Hence, EV advancement is currently concerned where batteries are the energy accumulating infers for EVs. This paper discusses recent trends and developments in battery deployment for EVs. Systematic reviews on explicit energy, state-of-charge, thermal efficiency, energy productivity, life cycle, battery size, market revenue, security, and commerciality are provided. The review includes battery-based energy storage advances and their development, characterizations, qualities of power transformation, and evaluation measures with advantages and burdens for EV applications. This study offers a guide for better battery selection based on exceptional performance proposed for traction applications (e.g., BEVs and HEVs), considering EV’s advancement subjected to sustainability issues, such as resource depletion and the release in the environment of ozone and carbon-damaging substances. This study also provides a case study on an aging assessment for the different types of batteries investigated. The case study targeted lithium-ion battery cells and how aging analysis can be influenced by factors such as ambient temperature, cell temperature, and charging and discharging currents. These parameters showed considerable impacts on life cycle numbers, as a capacity fading of 18.42%, between 25–65 °C was observed. Finally, future trends and demand of the lithium-ion batteries market could increase by 11% and 65%, between 2020–2025, for light-duty and heavy-duty EVs.

Dendrite-Free Zinc-Based Battery with High Areal Capacity via the Region-Induced Deposition Effect of Turing Membrane

Zinc-based batteries are promising for use as energy storage devices owing to their low cost and high energy density. However, zinc chemistry commonly encounters serious dendrite issues, especially at high areal capacities and current densities, limiting their application. Herein, we propose a novel membrane featuring ordered undulating stripes called "Turing patterns", which can effectively suppress zinc dendrites and improve ion conductivity. The crests and troughs in the Turing membrane can effectively adjust the Zn(OH)₄^2- distribution and provide more zinc deposition space. The coordinated Cu ions during membrane formation can interact with Zn(OH)₄^2-, further smoothing zinc deposition. Even at a high current density of 80 mA·cm^-2, the Turing membrane enables an alkaline zinc-iron flow battery (AZIFB) to work stably with an ultrahigh areal capacity of 160 mA·h·cm^-2 for approximately 110 cycles, showing an energy efficiency of 90.10%, which is by far the highest value ever reported among zinc-based batteries with such a high current density. This paper provides valid access to zinc-based batteries with high areal capacities based on membrane design and promotes their advancement.