Achieving Ah-Level Zn–MnO2 Pouch Cells via Interfacial Solvation Structure Engineering

Polymer-adjusted zinc anode towards high-performance aqueous zinc ion batteries

Aqueous zinc-ion batteries (AZIBs) have been investigated intensively as effective energy storage devices that are environmentally friendly, safe, and have a lower cost than current Li-ion batteries.[1-5] Being outstandingly safe due to usage of non-organic electrolyte, AZIBs could also be used as power supply for wearable electronics. This also put high standard requirements in terms of flexibility, stability and electrochemical performance to AZIBs. On the other hand, the general challenges, such as the formation of the dendrites on the Zn anodes, hydrogen evolution and side reactions, have been obstructing the practical application of AZIBs. In this presentation, a simple method to assemble quasi-solid-state Zn ion pouch cell with excellent mechanical performance, flexibility and electrochemical performance was developed, combining in-situ electrodeposition of MnO2 cathode and aramid nano fiber-based hydrogel with Zn plate as anode. In-situ and cycling measurements of the electrodeposition of MnO2 on carbon nanotube mat shows excellent capacitance and superior cycling stability. In addition, Kevlar derivatized aramid nanofiber-based hydrogel shows extremely strong strength when combined with polyvinyl alcohol, which prolonged the lifetime of the cell by preventing Zn dendrite growth largely.[5,6] Moreover, the method to assemble the AZIBs pouch cell enables us to optimize the process, decrease the steps, and save time effectively by taking advantage of hydrogel formation stage and avoiding conventional verbose slurry-casting-drying steps. This work paves an efficient path to assemble flexible and stable AZIBs pouch cells with high capacity and cycling stability.[1] Tang, Boya, et al. "Issues and opportunities facing aqueous zinc-ion batteries." Energy & Environmental Science 12.11 (2019): 3288-3304.[2] Li, Chang, et al. "Toward practical aqueous zinc-ion batteries for electrochemical energy storage." Joule 6.8 (2022): 1733-1738.[3] Yu, Feng, et al. "An aqueous rechargeable zinc-ion battery on basis of an organic pigment." Rare Metals 41.7 (2022): 2230-2236.[4] Lin, Yuexing, et al. "Dendrite-free Zn anode enabled by anionic surfactant-induced horizontal growth for highly-stable aqueous Zn-ion pouch cells." Energy & Environmental Science 16.2 (2023): 687-697.[5] Wang, Peng, and Petru Andrei. "High Performance Separator and Hydrogel Based on Aramid Fibers for Zn Ion Batteries." Electrochemical Society Meeting s 242. No. 4. The Electrochemical Society, Inc., 2022.[6] Xu, Lizhi, et al. "Water‐rich biomimetic composites with abiotic self‐organizing nanofiber network." Advanced Materials 30.1 (2018): 1703343.

Aqueous zinc (Zn) ion batteries (AZIBs) have not yet fulfilled their talent of high safety and low cost since the anode/electrolyte interface (AEI) has long been impeded by hydrogen evolution, surface corrosion, dendritic growth, and by‐product accumulation. Here, the hydrolysis of solid buffers is elaborately proposed to comprehensively and enduringly handle these issues. Take 2D layered black phosphorus (BP) as a hydrolytic subject. It is reported that the phosphoric acid generated by hydrolysis in an aqueous electrolyte produces a zinc phosphate (ZPO) rich solid electrolyte interphase (SEI) layer, which largely inhibits the dendrite growth, surface corrosion, and hydrogen evolution. Meanwhile, the hydrolytic phosphoric acid stabilizes the pH value near AEI, avoiding the accumulation of alkaline by‐products. Notably, compared with the disposable ZPO engineerings of anodic SEI pre‐construction and electrolyte additive, the hydrolysis strategy of BP can realize a dramatically prolonged protective effect. As a result, these multiple merits endow BP modified separator to achieve improved stripping/plating stability toward Zn anode with more than ten times lifespan enhancement in Zn||Zn symmetrical cell. More encouragingly, when coupled with a V2O5·nH2O cathode with ultra‐high loadings (34.1 and 28.7 mg cm−2), the cumulative capacities are remarkably promoted for both coin and pouch cells.

The optimization electrolyte strategy through molecular additives to improve the stability of aqueous zinc‐ion batteries (AZIBs), which changes the solvation structure of hydrated zinc ions (Zn2+), generally relies on experimental trial and error, because the precise mechanism by which these additives alter the coordination environment of Zn2+ remains elusive. Here, we select the oligopeptide of mono‐, di‐, tri‐, and tetra‐glycine, as electrolyte additives to optimize the Zn2+ solvation microenvironment in AZIBs. Contrary to traditional views, we find that these additives modify the solvated structure of the Zn2+ by substituting sulfate ion (SO42−) in the preexistence of Zn2+‐SO42− ion pair, rather than water molecules in the first solvation shell, due to a high energy barrier to replace one of the coordinated water molecules of Zn2+. This observation is consistent with recent experimental result of the attenuating influence of glycine on the interaction between Zn2+ and SO42− confirmed by Fourier‐transform infrared spectroscopy. For the multifunctional triglycine, its favorable conformation is disrupted to accommodate the direct coordination of oxygen atoms with Zn2+, and Zn2+ is observed to migrate between distinct sites along the triglycine backbone. This work provides theoretical principles to rationally design advanced electrolytes for solvation modulation with high performance AZIBs.

Advances in application of sustainable lignocellulosic materials for high-performance aqueous zinc-ion batteries

Layered MnO2@PDA as cathode material toward high-performance aqueous zinc-ion batteries

Rechargeable aqueous zinc-ion batteries (ZIB) sparked a considerable surge of research attention in energy storage systems due to its environment benignity and superior electrochemical performance. Up to now, less efforts to delve into mechanisms of zinc metal anode and their electrochemical performance. Zn metal anodes sustain thorny issues with Zn dendrite growth, hydrogen evolution reaction, and Zn corrosion irreversible byproduct formation, which results in low coulomb efficiency (CE) and poor cycle ability of the battery. Herein, we reveal the fundamental understanding of the above issue, outline four step, including mass transfer, desolvation process, charge transfer and Zn cluster formation. It can be clearly seen from reported strategies to promote Zn anode stability that deals with one or more steps, thereby boosting the understanding of the issues of Zn anodes and benefiting the rational design to surmount the issue. We also sum up advanced materials and structure design such as the design of the anode surface and internal structure, electrolyte strategies, and multifunctional separators. Finally, possible tactics and future innovation direction for Zn-based batteries are proposed to achieve high performance aqueous Zinc-ion batteries.

Stabilization of cathode electrolyte interphase for aqueous zinc-ion batteries

Aqueous zinc-ion batteries (AZIBs) represent viable options for large-scale energy storage, attributed to their high theoretical capacity, availability of resources, and intrinsic safety features. However, the zinc-water interface poses significant challenges including dendrite growth, hydrogen evolution, and corrosion, which considerably restrict battery performance. This review systematically examines organic additive strategies for zinc anode interface regulation in AZIBs. Structure-property relationships are established correlating molecular design with interfacial behavior through three fundamental mechanisms, which are electric double layer (EDL) modulation, solvation structure optimization via coordination effects, and controlled solid electrolyte interphase (SEI) formation. The review analyzes adsorption mechanisms of organic additives, distinguishing between physical adsorption-based and SEI-forming additives, where the former dynamically modulates the interfacial environment, while the latter establishes durable protective layers. Multifunctional additives integrating multiple regulatory mechanisms demonstrate superior performance optimization. Comparative analysis reveals that liquid organic additives excel in solvation structure regulation, whereas solid additives show advantages in interfacial adsorption and SEI engineering. Through systematic analysis of reported molecules, design principles are established linking molecular features to interfacial properties, providing guidance for rational development of next-generation organic additives in high-performance AZIBs.

Versatile additive for enhancing the stability of Zn Anode: Pyrrolidine-based ionic liquid

Non-sacrificial anionic surfactant with high HOMO energy level as a general descriptor for zinc anode

The strong electrostatic interaction between high-charge-density zinc ions (112 C mm-3 ) and the fixed crystallinity of traditional oxide cathodes with delayed charge compensation hinders the development of high-performance aqueous zinc-ion batteries (AZIBs). Herein, to intrinsically promote electron transfer efficiency and improve lattice tolerance, a revolutionary family of high-entropy oxides (HEOs) materials with multipath electron transfer and remarkable structural stability as cathodes for AZIBs is proposed. Benefiting from the unique "cock-tail" effect, the interaction of diverse type metal-atoms in HEOs achieves essentially broadened d-band and lower degeneracy than monometallic oxides, which contribute to convenient electron transfer and one of the best rate-performances (136.2 mAh g-1 at 10.0 A g-1 ) in AZIBs. In addition, the intense lattice strain field of HEOs is highly tolerant to the electrostatic repulsion of high-charge-density Zn2+ , leading totheoutstanding cycling stability in AZIBs. Moreover, the super selectability of elements in HEOs exhibits significant potential for AZIBs.

Anti-corrosive and carbonyl-rich interlayer enables highly reversible zinc anode

Aqueous zinc-ion batteries (AZIBs) have been receiving continuous attention as candidates for the next generation of safe batteries, but the poor reversibility of the Zn anode limits their further development. In recent years, researchers have been obsessed with modifying the surface of the Zn anode and adjusting the solvation structure of Zn2+ to address these challenges. Here, we present a novel strategy to improve the reversibility of the Zn anode by simultaneously regulating the zinc ion flow and dividing micro-corrosion zones on the surface of the Zn anode, thereby manipulating the deposition behavior of Zn2+ and relieving the corrosion of the Zn anode. This approach exploits the keto-enol tautomerism of α-acetyl-γ-butyrolactone (ABL) to develop a specifically designed additive: Zn2+ coordinated α-acetyl-γ-butyrolactone complex (ZnABL). With this innovative additive, the Zn anodes showed excellent reversibility: the Zn||Zn symmetric cell achieved a long cycle life of 7780 h (about 11 months) and the Coulombic Efficiency averagely reached a high value of 99.87 %. Furthermore, the Zn||Zn0.25V2O5·H2O near-ampere-hour pouch cell, featuring a high areal capacity of 7.9 mAh cm-2, achieved an energy density of 106.17 Wh L-1 and sustained more than 350 cycles. The success of ZnABL in modulating the zinc ion flow and compartmentalizing the micro-corrosion zone provides a novel option for the reversibility improvement of Zn anodes.

Boosting uniform nucleation and suppressing hydrogen evolution with an in-situ formed zinc hyaluronate protective film on zinc anodes