Tuning the Electrode/Electrolyte Interface Enabled by a Trifunctional Inorganic Oligomer Electrolyte Additive for Highly Stable and High‐Rate Zn Anodes

Abstract

The practical application of aqueous Zn‐ion batteries is still greatly hindered by the unstable Zn anode with severe Zn dendrites growth and side reactions. As it is accessible and economical, the exploitation of electrolyte additives is one of the most promising strategies to stabilize the Zn electrode/electrolyte interface. Herein, the penta‐potassium triphosphate (KTPP) as a novel trifunctional electrolyte additive is introduced to tune the electrode/electrolyte interface. First, the KTPP additive can induce an ion‐conducting and mechanically robust solid electrolyte interphase film to stabilize the Zn anode. Second, the KTPP can complex with Zn2+ ions to reconstitute the dissolution sheath structure of the Zn2+ ion. Finally, the K+ cations in KTPP adsorb on the tips of the Zn anode surface as a shielding film to regulate Zn2+ ion flux. As a result, Zn//Zn symmetric cells can achieve significantly prolonged cycling stability (e.g., from 1077 to 3800 h at 1 mA cm−2/1 mAh cm−2, from 256 to 2500 h at 2 mA cm−2/2 mAh cm−2), and ultrahigh cumulative capacity of 6400/7200 mAh cm−2 at high current density (40/20 mA cm−2). A four‐layer Zn–MnO2 pouch full cell with a high capacity of 9 mAh can be constructed, showing impressive practical application potential.

Employing a chelating agent as electrolyte additive with synergistic effects yields highly reversible zinc metal anodes

“…43,53 Generally, there are two forms of the solvation structure of Zn 2+ , solvent-separated ion pair (SIP, [Zn 2+ -(H 2 O) 6 ·SO 4 2− ]) and contact ion pair (CIP, [Zn 2+ -(H 2 O) 5 ·OSO 3 2− ]). 6,31 The primary solvent shell (PSS, Zn 2+ -(H 2 O) 6 ) (Fig. 2b) formed owing to the electrostatic attraction of Zn to H 2 O molecules displays obvious electrostatic repulsion, which is an important reason hindering the transportation of zinc ions.…”

“…Electrolyte additives play a significant role in both the solvation structure of Zn 2+ and Zn anode/electrolyte interfacial interaction modulation. For example, ionic additives with low reduction potentials, such as K + , 31 Li + , 32 Na + , 33 La 3+ , 34 Ce 3+ , 35 and Al 3+ , 36 could adsorb on the tip of Zn anode surface to form an electrostatic shield shell, thus achieving uniform deposition of zinc ions. Unfortunately, the heavy metal salt additives will not only increase the cost of battery manufacture, but also cause serious environmental pollution issues, drastically diminishing the advantages of aqueous ZIBs.…”

Recent advances in aqueous zinc–sulfur batteries: overcoming challenges for sustainable energy storage

“…With a larger deposition surface, the zinc ions would be distributed more evenly, leading to a reduced propensity for dendritic growth. 122–125…”

Achieving Planar Zn Deposition Enabled by an Eco-Friendly and Mechanically Robust Dual Cross-Linking Dynamic Network Coating for Long-Lifespan Zn-Ion Batteries

“…In recent years, different methods have been suggested to solve these problems in AZIBs, such as electrolyte component optimization, − Zn anode material design, − and electrode–electrolyte interface modification. − In these methods, setting up a protective layer between the electrolyte and the Zn anode has been effectively proven as a promising strategy to inhibit side reactions and dendrite growth. For instance, Xie et al prepared a three-dimensional (3D) nanoporous ZnO coating on Zn foil by in situ Zn­(OH) 4 2– deposition.…”