Organic–Inorganic Hybrid Cathode with Dual Energy‐Storage Mechanism for Ultrahigh‐Rate and Ultralong‐Life Aqueous Zinc‐Ion Batteries

Abstract

The exploitation of cathode materials with high capacity as well as high operating voltage is extremely important for the development of aqueous zinc‐ion batteries (ZIBs). Yet, the classical high‐capacity materials (e.g., vanadium‐based materials) provide a low discharge voltage, while organic cathodes with high operating voltage generally suffer from a low capacity. In this work, organic (ethylenediamine)–inorganic (vanadium oxide) hybrid cathodes, that is, EDA‐VO, with a dual energy‐storage mechanism, are designed for ultrahigh‐rate and ultralong‐life ZIBs. The embedded ethylenediamine (EDA) can not only increase the layer spacing of the vanadium oxide, with improved mobility of Zn ions in the V–O layered structure, but also act as a bidentate chelating ligand participating in the storage of Zn ions. This hybrid provides a high specific capacity (382.6 mA h g−1 at 0.5 A g−1), elevated voltage (0.82 V) and excellent long‐term cycle stability (over 10 000 cycles at 5 A g−1). Assistant density functional theory (DFT) calculations indicate the cathode has remarkable electronic conductivity, with an ultralow diffusion barrier of 0.78 eV for an optimal Zn‐ion diffusion path in the EDA‐VO. This interesting idea of building organic–inorganic hybrid cathode materials with a dual energy‐storage mechanism opens a new research direction toward high‐energy secondary batteries.

Amphipathic Molecules Endowing Highly Structure Robust and Fast Kinetic Vanadium‐Based Cathode for High‐Performance Zinc‐Ion Batteries

“…More impressively, TBAVO has 92% capacity retention during 1600 cycles even at À40 °C (Figure 3g), meaning that TBAVO has excellent cycle stability and temperature adaptability. This is due to the following reasons: 1) Lower zinc ion desolvation energy can facilitate the desolvation of zinc ions, boosting the charge-transfer rate; 2) A wider interlayer spacing benefits the intercalation and deintercalation of Zn 2þ , [51] increasing zinc ions diffusion coefficient [52,53] ;…”

“…Besides, the XPS peak of -N þ - [51] gradually increases while the peak of N-C gradually weakens when discharging to 0.2 V (Figure S22, Supporting Information), which further proves that the TBA þ interacts with the Zn 2þ (Scheme 1c) and participates in the entire charge-storage process. [60] Based on the aforementioned results, the reaction mechanism of the whole process can be proposed in Figure 5a. First, when the cathode is immersed in Zn(OTF) 2 electrolyte, the interlayer spacing of the cathode is slightly increased due to the preintercalation of Zn 2þ (Figure S19, Supporting Information).…”

“…More impressively, TBAVO has 92% capacity retention during 1600 cycles even at −40 °C (Figure 3g), meaning that TBAVO has excellent cycle stability and temperature adaptability. This is due to the following reasons: 1) Lower zinc ion desolvation energy can facilitate the desolvation of zinc ions, boosting the charge‐transfer rate; 2) A wider interlayer spacing benefits the intercalation and deintercalation of Zn 2+ , [ 51 ] increasing zinc ions diffusion coefficient [ 52,53 ] ; 3) The intercalation of TBA + reduces the entry of structural water molecules in vanadium cathode during cycling, maintaining the structural integrity of the cathode. [ 39 ] 4) The usage of ultra‐freeze‐resistant low‐temperature ZnClO 4 /NaClO 4 electrolyte, with a freezing point far below −40 °C.…”

Advances of Metal Oxide Composite Cathodes for Aqueous Zinc‐Ion Batteries

“…As a consequence, the approach failed to solve the problem of low redox potential in vanadium‐based electrodes. [ 100 ] Polymer compositing has emerged as a positive strategy for improving the aggregate of the lattice framework, alleviating structural collapse of the hosts, and reducing capacity fading during cycling, which benefits from the elasticity provided by bulk molecular integration and interlinking technology. These characteristics, when combined, lead to high‐performance electrode materials.…”

“Three‐in‐One” Strategy that Ensures V2O5·nH2O with Superior Zn2+ Storage by Simultaneous Protonated Polyaniline Intercalation and Encapsulation

“…[1][2][3][4][5] Encouragingly, among these AMIBs, aqueous zinc-ion batteries (AZIBs) have the potential to be the complements to LIBs due to fine safety, abundant resources, and high theoretical specific capacity of zinc anode (820.0 mAh g À1 ). [6][7][8][9] Notably, cathode materials are the predominant components for AZIBs. Among the well-explored manganese oxides, vanadium oxides, Prussian blue-like materials, etc., vanadium oxides with various valences, layered structures, and rich reserves have received massive research enthusiasm in recent years.…”