Regulating Dendrite-Free Zn Deposition by a Self-Assembled OH-Terminated SiO₂ Nanosphere Layer toward a Zn Metal Anode

Abstract

Zn dendrite growth during repeated plating and stripping of a Zn metal anode often causes short-circuiting by puncturing the separator. Herein, we propose a separator modification strategy to regulate the Zn-ion flux and achieve uniform Zn deposition through the OH-terminated SiO 2 nanosphere coating. The interspaces between the uniform SiO 2 nanospheres construct a network of Zn-ion transport channels, and the negatively charged hydroxyl groups on the surface of SiO 2 nanospheres can electrostatically attract the Zn ions to direct the ion migration. The negative charges on SiO 2 nanospheres are retained at a higher pH, which enables the SiO 2 coating to consistently regulate the Zn-ion flux in the operating pH range of the Zn stripping/plating process. With a uniform Zn deposition guided by the SiO 2 coating, the dendrite formation is suppressed and the side reactions are alleviated. As a result, the Zn||Zn symmetric cell achieves a cyclic life of 1000 h at both 3 and 5 mA cm −2 . Meanwhile, the Zn||Cu asymmetric cell is able to maintain a Coulombic efficiency of 99.62% at 1 mA cm −2 for 2000 cycles, which outperforms many previously reported strategies.

Highly-reversible and recyclable zinc metal batteries achieved by inorganic/organic hybrid separators with finely tunable hydrophilic–hydrophobic balance

“…S14, ESI†) show a peak shift to a higher binding energy as well as a higher surface hydroxyl signal, implying the decrease of the proportion of Si–O–Si and the increase of the proportion of Si–OH in FS. 33,49 Interestingly, the zeta potential with FS in different pH environments also confirms the presence of hydroxyl groups with negative charges (Fig. S15a, ESI†).…”

“…31,32 Furthermore, the strong hydrophilicity of the GF separator leads to its weak barrier effect on free water molecules, which induces more serious side reactions on the zinc side, and then affects the coulombic and energy efficiency of AZMBs. 7 Surface modification methods such as drop casting, 33 soaking, 34 filtrating 35 or hydrothermal treatment, 36 and even textile-derived separators 37 reported before can partially improve the stability towards the Zn metal anode, however, fail in industrial amplification, and especially show insufficient dendrite resistance under extreme working conditions, e.g. a high deposition current density and high DOD.…”

Improved Strategies for Separators in Zinc‐Ion Batteries

“…Xu et al. developed a creative and malleable separator based on used ZrO 2 fibers for aqueous ZIBs by utilizing a wet meshing technique [66] . ZrO 2 separator has super high wettability and heat resistance.…”

“…Xu et al developed a creative and malleable separator based on used ZrO 2 fibers for aqueous ZIBs by utilizing a wet meshing technique. [66] ZrO 2 separator has super high wettability and heat resistance. This button cell, which consists of a zinc sheet anode, an ammonium vanadate cathode, and ZrO 2 separators, has a remarkable specific capacity of 390 mAh g À 1 at a current density of 0.15 A g À 1 .…”

Transforming Dye Molecules into Electrochemical Allies: Direct Red 80 as a Dual-Functional Electrolyte Additive for Dendrite-Free Aqueous Zinc-Ion Batteries

“…Despite the unique advantages of AZIBs, they face significant barriers of poor cell reversibility and short life due to localized dendrites, side reactions, and corrosion passivation. , In response, researchers have proposed a range of initiatives, including electrode structure design, , interface coating, − electrolyte optimization, − and separator modification. − Among these, the addition of electrolyte additives is a promising and cost-effective solution for industrial mass production. Normally, the dissociated Zn 2+ ions in zinc brine solution tend to combine with polar water molecules, resulting in solvated Zn­(H 2 O) 6 2+ ions. , During the electrochemical cycling process, these solvated ions come into contact with the anode and trigger the water-induced side reactions, resulting in the formation of zinc hydroxyl sulfate and H 2 .…”