Intrinsic Hydrogen‐Bond Donors‐Lined Organophosphate Superionic Nanochannels Levering High‐Rate‐Endurable Aqueous Zn Batteries

Abstract

While being promising, aqueous Zn batteries (AZBs) are still facing severe Zn corrosion and competitive hydrogen evolution issues. [5][6][7][8][9][10] The local pH elevation induced by hydrogen evolution and Zn corrosion usually aggravates the accumulation of the insulative passivation layer, i.e., Zn 4 SO 4 (OH) 6 , leading to the final battery failure. [11][12][13] Recent strategies involving the use of electrolyte additives, [11,[14][15][16][17] organic electrolytes, [18] water-in-salts, [19,20] hybrid electrolyte, and AFLs have witnessed improved Zn anode stability. Among them, engineering AFLs can effectively cut off the electron gain or loss of water molecules, and has no kinetics penalty occurring in organic or gel electrolytes as well as cost issues from water-in-salts, thus being considered as one of the highly anticipated tactics to avoid Zn corrosion and hydrogen evolution reactions. [21][22][23][24][25] The ideal AFL should be capable of fast Zn 2+ conductivity yet electron insulation, preventing from the intercontact of water and/or anions with Zn anode, and mechanical robustness. The key components of such AFLs can be generally categorized into two types: 1) intrinsic Zn 2+ conductors; 2) intrinsic Zn 2+ insulator but can be post-treated for Zn 2+ conduction. The compounds encompassing ZnS, ZnO, indium-based compounds, zirconium phosphates, and Zn phosphates, [26][27][28][29] despite being intrinsically Zn 2+ -conductive but no order channels with favorable dimensions for ionic diffusion, still show unsatisfactory ionic conductivity or Zn 2+ transference number. In addition, FLs based on such compounds usually lack a proper interfacial water wettability, which also negatively influences the electrochemical performance. On the other hand, recently, several extrinsic Zn 2+ conductors designed as AFLs, such as metal-organic frameworks, MXenes, Zeolites and their composites with commercial Nafion, [30][31][32][33] have provided inspiring prototypes. Such materials usually need to be preactivated for dozens of hours by immersing into Zn 2+ electrolytes, which is time-consuming. Moreover, while certain composites can be engineered to realize ionic redistribution and accurate interception of water molecules and/or anions, which usually need to use expensive materials such as Nafion. Thus, to explore new candidates for AFLs design is of extreme significance.Organic/inorganic hybrid artificial functional layer (AFL) designs of Zn anode have witnessed good progress in stabilizing the Zn anode. However, such processes remain uncapable of simultaneously providing durable protection and fast Zn 2+ migration, especially in high-rate scenarios. Herein, intrinsic hydrogen-bond donor (HBD)-lined organophosphate superionic nanochannels are initially engineered to address this challenge. Due to unique ordered nanochannels with a smaller diameter than that of hydrated Zn 2+ ions and polyanions, hydroxymethyl Zn phosphates (Zn(O 3 PCH 2 OH, ZnOPC) are first considered for AFL design. The small size can provide an interc...

Reversible adsorption with oriented arrangement of a zwitterionic additive stabilizes electrodes for ultralong-life Zn-ion batteries

“…S30, ESI†). 50,51 Besides, owing to the addition of l -CN, the full cells also achieve excellent rate capability over a wide range of current densities from 0.1 to 5 A g −1 (Fig. 5e), which can recover to 259.4 mA h g −1 with almost 100% capacity retention at 1 A g −1 .…”

Recent Progress on Zn Anodes for Advanced Aqueous Zinc‐Ion Batteries

“…al designed an intrinsic hydrogen‐bond donor (HBD)‐lined organophosphate—Zn(O 3 PCH 2 OH)(ZnOPC)—with superionic nanochannels of 3.878 Å. [ 123 ] The small channel size has a physical interception function for [Zn(H 2 O) 6 ] 2+ and polyanion and as HBDs, the abundant OH groups in the ion channels show a hydrogen‐bonding interaction with H 2 O molecules in hydrated cations, remarkably facilitating the de‐solvation process. Based on this, Zn@ZnOPC exhibits an ultrahigh‐rate performance of up to 50 mA cm −2 , accompanying by a 36% lower overpotential than that of bare Zn.…”

Cation and Anion Modulation Strategies toward Ideal Zinc Artificial Interface

“…Taking advantages of the smaller pore size than sulfate anions, artificial layer with the restricted structure has been designed to repel the penetration of sulfate groups, such as zeolite (Figure 6a), [49] and hydroxymethyl Zn phosphates (ZnO 3 PCH 2 OH, ZnOPC) (Figure 6b). [50] Figure 6a demonstrates the precise cation and anion sieving ability of Zn‐exchanged zeolite. In addition, the strong interaction between Zn 2+ and O facilitates the de‐solvation process and induces uniform Zn deposition based on a 3D diffusion mechanism [49] …”