Tuning the Kinetics of Zinc‐Ion Insertion/Extraction in V₂O₅ by In Situ Polyaniline Intercalation Enables Improved Aqueous Zinc‐Ion Storage Performance

Abstract

Rechargeable aqueous zinc-ion batteries (ZIB) are emerging as one promising alternative for Li-ion batteries on account of the high energy density, environmental friendliness, rich earth abundance and good safety characteristics. Nevertheless, almost all the ZIBs suffer from sluggish kinetics of Zn 2+ diffusion in electrodes, leading to poor rate capability and inadequate cycle life in practical applications. To tackle this issue, herein we develop an in situ polyaniline (PANI) intercalation strategy to facilitate the Zn 2+ (de)intercalation kinetics in V2O5. In this way, a remarkably enlarged interlayer distance (13.90 Å) can be constructed alternatively between the V-O layers, offering expedite This article is protected by copyright. All rights reserved.3 channels for facile Zn 2+ diffusion. More importantly, the electrostatic interactions between Zn 2+ and host O 2-, which is another key factor in hindering the Zn 2+ diffusion kinetics, can be effectively blocked by the unique π-conjugated structure of PANI. As a result, the PANI-intercalated V2O5 exhibits a stable and highly reversible electrochemical reaction during repetitive Zn 2+ insertion and extraction, as demonstrated by in situ synchrotron X-ray diffraction and Raman studies. Further first-principles calculations clearly reveal a remarkably lowered binding energy between Zn 2+ and host O 2+ , which explains the favorable kinetics in PANI-intercalated V2O5. Moreover, the intercalation of PANI leads to an intermediated energy band lying across the Fermi level, thereby offering a step for electron transport during charging/discharging process. Benefitting from the above, the overall electrochemical performance of PANI-intercalated V2O5 electrode has been remarkable improved, exhibiting excellent high rate capability of 197.1 mAh g −1 at current density of 20 A g −1 with capacity retention of 97.6% over 2000 cycles. Our approach presents a prospective guideline for the electrode design of high performance aqueous ZIBs, which could be also expanded to widespread battery researches.

VOPO4⋅2H2O Nanosheet Cathode for Enhanced Sodium Storage

“…However, the issues of limited reserves, uneven distribution and high price of lithium resources perplexed their large-scale energy storage applications in future (Wang et al, 2017;Guo et al, 2020) Among the post LIBs, Na-ion batteries (SIBs) have caused wide increasing concern due to the cheap price, rich reserve and even distribution of sodium resources in the crust of the earth (Chen S. et al, 2017;Yu et al, 2019;Zhao et al, 2019). However, the bulkier radius [1.02 (Na + ) vs. 0.76 Å (Li + )] makes the Na-ion diffusion more sluggish than that of Li-ions, resulting in the larger volume change, the lower special capacity and the poorer cyclical stability, which limit the further development of SIBs in large-scale energy storage system (Wang et al, 2018;Liu et al, 2020). Therefore, designing/exploring novel advanced electrodes for SIBs to facilitate fast Na-ion transfer is the top priority at present (Li C. et al, 2020;Wang B. et al, 2020).…”

Rechargeable Mild Aqueous Zinc Batteries for Grid Storage

“…Different "pillars" such as Na þ , Ca 2þ , Ni 2þ , Mg 2þ , Fe 2þ , Mn 2þ , Cu 2þ , and organic molecules, etc., have also been reported to expand the interlayer space and tighten up V m O n layers to avoid structure collapse during Zn 2þ ion storage (Figure 3d-g). [33][34][35][36][37][38] The reasons for the improved performance could be attributed to the following reasons. First, the pre-inserted metal ion pillars expand the initial interlayer distance of V 2 O 5 layers and facilitate Zn 2þ ion diffusion.…”

“…[40] In addition, in situ polyaniline (PANI) intercalation in V 2 O 5 also effectively expanded the interlayer space (13.9 Å) and blocked the strong electrostatic interaction between Zn 2þ ion and the host framework through unique π-conjugated PANI (Figure 3g). [37] Typically, the A x V 2 O 5 .xH 2 O underwent a reversible solidsolution reaction followed by phase-transition reactions during Zn 2þ intercalation and deintercalation. [33,36,40] The Zn 2þ ion was also believed to have intercalated as H 2 O-solvated Zn 2þ ions in certain A x V 2 O 5 .xH 2 O structures.…”

“…For different kinds of V-based cathodes, pillars such as alkaline metal ions, structural H 2 O, and organic molecules are critical for reversible Zn storage. [29,30,37] The structural and electrochemical stability of hydrate pillars and the fundamental role of pillars in the charge storage mechanisms in V-based oxide materials during long-term cycling are not nearly clarified. Precise control of the occupation sites, the specification and amount of pillars, and the strength of bonding between pillars and V m O n layers will be the key to balance the structural stability, charge storage capacity, and rate performance for layered V oxide cathodes.…”

Anisotropic Growth of Al‐Intercalated Vanadate by Tuning Surface Hydrophilicity for High‐Rate Zn‐Ion Storage

“…[1][2][3][4][5][6][7][8] Thus, ZIBs are deemed as one of the most promising configurations for grid-scale energy storage. [9][10][11][12][13][14][15][16][17][18][19] Among the cathodes of ZIB, layered cation-intercalated vanadate materials are exceptional candidates due to their multiple oxidation states, tunable intercalation species, and interlayer spacing, thus have been widely investigated. [20][21][22][23][24][25][26][27] However, these vanadates readily suffer from degradation/structural collapse probably by forming insulating precipitates even in mild acidic/near-neutral electrolytes, which greatly impedes their electrochemical and cycling performance.…”