Cation‐Selective Interface for Kinetically Enhanced Dendrite‐Free Zn Anodes

Abstract

standard hydrogen electrode (SHE)], natural abundance, and excellent safety of Zn anode, aqueous zinc-ion batteries (AZIBs) have recently attracted considerable research attention. [1][2][3][4] Nevertheless, dendrite growth, corrosion, and passivation at the anode-electrolyte interface hinder the widespread practical application of AZIBs. [5,6] Specifically, cumulatively grown dendrites pierce the separator, resulting in poor battery performance and even fire hazards. Additionally, the accumulation of insulating products through interfacial side reactions and the hydrogen evolution reaction (HER) at Zn anodes can severely reduce the coulombic efficiency (CE) and unevenly deposit Zn. [7][8][9][10] Hence, efficient measures are urgently required to protect Zn anodes.Recently, several strategies such as surface modification [11][12][13] and electrolyte manipulation [14][15][16][17][18] have been developed to solve these problems. Surface modification by creating a protective layer onto the Zn surface gains wide attention on account of the merits of simple and effective. [19] Previous studies have generally emphasized that protective layers have significant effect on promoting uniform Zn 2+ ion distribution and preventing direct contact of Zn anode with electrolyte, thereafter contributing to dendrite-free and side reactioninhibited Zn anode. [20][21][22][23][24] Going further, it should be pointed out that Zn 2+ ion exists as hydrated [Zn(H 2 O) 6 ] 2+ ion structure in aqueous electrolyte and the desolvation process is necessary before Zn deposition. [3] Moreover, the detrimental HER directly relates to the amount of free water at the electrode-electrolyte interface. Besides, the side reaction-resulted passiviation byproduct is usually Zn 4 SO 4 (OH) 6 •xH 2 O (ZSH) in ZnSO 4 electrolyte, [6,10] which simultaneously involves SO 4 2− ions and water molecules. This is to say, decreasing the number of SO 4 2− ions and free water near the Zn-electrolyte interface is significantly important in the side reaction-inhibited chemistry, which, however, has rarely attracted much attention. [27] In addition, noting that hydrated [Zn(H 2 O) 6 ] 2+ ions own high charge density and easily combine with anions, the desolvation penalty impedes the homogeneous Zn 2+ ion diffusion on the Zn anode. [25,26] In this regard, creating an artificial protective interface that simultaneously with good cation-selectivity and superior desolvation role is vitally important for homo geneous and kinetically enhanced Zn deposition, as well as side reaction-inhibited Zn anode.The Zn anode in aqueous zinc-ion batteries (AZIBs) is severely impeded by uncontrolled dendrite growth and promiscuous water-induced side reactions, resulting in low Coulombic efficiency (CE) and poor lifetime. Herein, a versatile Zn-based laponite (Zn-LT) interface is constructed for uniform and rapid Zn deposition for long-life AZIBs. The combined experimental results and theoretical simulations reveal that the abundant negatively charged channels in the Zn-LT layer permit cat...

Suppressing Dendrite Growth and Side Reactions via Mechanically Robust Laponite-Based Electrolyte Membranes for Ultrastable Aqueous Zinc-Ion Batteries

“…Despite the substantially increased viscosity, the LP9 electrolyte membrane exhibits a high ionic conductivity of 19.6 mS/cm, albeit lower than that (51.9 mS/cm) of the BE, surpassing the performance of previously reported gel electrolytes and water-in-salt electrolytes. , Moreover, as shown in Figure S10, the LP9 electrolyte membrane exhibits a Zn 2+ transference number of 0.76, higher than those of conventional liquid electrolytes. , This could be attributed to the 2D nanostructures and the highly negatively charged basal plane of the LP nanocrystals, which facilitate fast cation diffusion in the quasi-solid-state electrolyte membrane , Figure d presents the storage modulus ( G′ ) of the LP-based electrolyte membranes, and the inserted optical image shows the appearance of a freestanding LP9 electrolyte membrane. Notably, the LP6 and LP9 electrolyte membranes exhibit high G′ values of 0.8 and 2.0 MPa, respectively, signifying their exceptional mechanical resistance against Zn dendrite growth.…”

“…49,50 This could be attributed to the 2D nanostructures and the highly negatively charged basal plane of the LP nanocrystals, which facilitate fast cation diffusion in the quasi-solid-state electrolyte membrane. 4849,51 Figure 2d presents the storage modulus (G′) of the LP-based electrolyte membranes, and the inserted optical image shows the appearance of a freestanding LP9 electrolyte membrane. Notably, the LP6 and LP9 electrolyte membranes exhibit high G′ values of 0.8 and 2.0 MPa, respectively, signifying their exceptional mechanical resistance against Zn dendrite growth.…”

In Situ Growth of an Ultrathin Polymer Brush Layer Enables a Reversible Zinc Anode

“…As shown in Figure a, the transfer process of Zn 2+ can be regulated by the PSBMA SEI layer. Due to the abundant –SO 3 – groups in the PSBMA polymer brushes, Zn 2+ can be attracted by the electrostatic attraction, which promotes the desolvation process of [Zn­(H 2 O) 6 ] 2+ and the migration of Zn 2+ . Moreover, the evenly distributed –SO 3 – can ensure a uniform flux of Zn 2+ , avoiding excessive local electric field intensity and ensuring the uniform deposition of Zn.…”

“…− groups in the PSBMA polymer brushes, Zn 2+ can be attracted by the electrostatic attraction, which promotes the desolvation process of [Zn(H 2 O) 6 ] 2+ and the migration of Zn 2+ . 29 Moreover, the evenly distributed −SO 3 − can ensure a uniform flux of Zn 2+ , avoiding excessive local electric field intensity and ensuring the uniform deposition of Zn. The sulfonic acid group can also prevent SO 4…”

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

“…Lower potentials indicated that the charge distribution at the Zn-CCS interface was changed and the adsorption of anions was significantly weakened in the same environment. 30,31 Besides, Zn-CCS was rich in hydrophilic functional groups and had a network-like surface with a high specific surface area, which made it have good wettability to aqueous electrolytes than bare Zn (89°) and was beneficial for the Zn ion diffusion (Figure 2i). 32 Among this, the surface morphology becomes flat from unevenness as the electrodeposition time grows with the continuous generation of Zn-CCS, and thus, the apparent contact angle continues to increase (30 s−37°, 60 s−44°, 90s-50°, 120s-52°, 150s-68°, 180s-73°).…”