Synergistic Cooperation of Zn(002) Texture and Amorphous Zinc Phosphate for Dendrite-Free Zn Anodes

Abstract

Zn anodes of aqueous Zn metal batteries face challenges from dendrite growth and side reactions. Building Zn(002) texture mitigates the issues but does not eradicate them. Zn(002) still faces severe challenges from corrosive electrolytes and dendrite growth, especially after hundreds of cycles. Therefore, it is necessary to have a passivation layer covering Zn(002). Here, Zn(002) texture and surface coating are achieved on Zn foils by an one-step annealing process, as demonstrated by ZnS, ZnSe, ZnF2, Zn3(PO4)2 (ZPO), etc. Using ZPO as a model, the coupling between surface coating and Zn(002) is illustrated in terms of dendrite-suppressing ability and diffusion energy barrier of Zn2+. The modified Zn foils (Zn(002)@ZPO) exhibit the excellent electrochemical performance, far superior to Zn(002) or ZPO alone. In the full cells, the performance is greatly improved even under harsh conditions, i.e., high areal capacity and limited Zn resource. This work achieves crystal engineering and surface coating on Zn anodes simultaneously and discloses the in-depth insights about the synergy of crystal orientation and passivation layers.

Orientational Electrodeposition of Highly (002)-Textured Zinc Metal Anodes Enabled by Iodide Ions for Stable Aqueous Zinc Batteries

“…Even at 20 mAh cm –2 at 1 mA cm –2 corresponding to ∼71.7% depth of discharge (DOD), this H-(002)-Zn can still stably cycle over 500 h with steady voltage curves (Figure f), significantly surpassing the (101)-Zn counterpart (Figure S27). Compared with the state-of-the-art Zn electrodes, ,,,,,,,,,,− the tailored H-(002)-Zn manifests superior performances in terms of DOD, cycling time, and areal capacity (Figure g and Table S2).…”

“…Electrochemical energy storage technologies are of significance for efficiently integrating sustainable natural sources. − Among various options, rechargeable aqueous Zn metal batteries (RAZMBs) are practically promising due to the Zn merits involving materials abundance, low-cost, high theoretical capacity (820 mAh g –1 ), and intrinsic safety in aqueous electrolytes. − However, conventional Zn anodes often suffer from poor reversibility ascribed to severe dendrite growth, hydrogen evolution reaction (HER), and Zn corrosion even in mild acidic or neutral aqueous electrolytes, hindering the industrialization of RAZMBs. − Moreover, the HER would induce loose Zn deposition, exacerbate electrolyte consumption, and increase the local pH environment near Zn to provoke the formation of inactive byproducts, resulting in low Zn utilization and rapid battery failure. − In addition, the dendric Zn growth with irregular morphology will inevitably deteriorate the parasitic reactions and render short circuits of batteries. − Strategies for alleviating these issues have been proposed focusing on constructing artificial protective layers on Zn, − formulating electrolyte compositions, − modifying separators, , and designing host structures. − …”

Zn(002)-preferred and pH-buffering triethanolamine as electrolyte additive for dendrite-free Zn anodes

“…3–5 These factors work together and ultimately lead to cell failure. 6 Therefore, numerous strategies have been developed to address these challenges, such as three-dimensional (3D) current collectors, 7,8 protective layers, 9–12 separator modification 13,14 and electrolyte optimization. 15–19…”

“…[3][4][5] These factors work together and ultimately lead to cell failure. 6 Therefore, numerous strategies have been developed to address these challenges, such as three-dimensional (3D) current collectors, 7,8 protective layers, [9][10][11][12] separator modification 13,14 and electrolyte optimization. [15][16][17][18][19] Among these strategies, titrating the electrolyte composition is often achieved using electrolyte additives, which is particularly attractive due to its convenience and high effectiveness.…”

Trade-Off between Rough and Smooth Electrode Surfaces toward Stable Zn Stripping/Plating in Aqueous Electrolytes

“…Furthermore, safety concerns stemming from the flammability and potential for explosions associated with organic electrolytes persist. − As a promising alternative technology, aqueous Zn ion batteries (AZIBs) have shown great potential for large-scale energy storage due to their low cost, high safety, and environmental friendliness. Zn foils, characterized by their notable attributes of high volumetric capacity (5855 mAh cm –3 ), high stability, and good flexibility, can be used directly as the anodes for AZIBs. − During battery cycling, a portion of the Zn metal actively functions as the anode, while the remaining portion serves as the current collector, facilitating deposition of Zn, which could simplify the manufacturing process and reduce the cost of the battery products. Nevertheless, the electrochemical performance of AZIBs is seriously hindered by the complex parasitic reactions on the Zn anode including corrosion, hydrogen evolution, and byproducts .…”