In Situ Electrochemical Activation of Hydroxyl Polymer Cathode for High‐Performance Aqueous Zinc–Organic Batteries

Abstract

The slow reaction kinetics and structural instability of organic electrode materials limit the further performance improvement of aqueous zinc‐organic batteries. Herein, we have synthesized a Z‐folded hydroxyl polymer polytetrafluorohydroquinone (PTFHQ) with inert hydroxyl groups that could be partially oxidized to the active carbonyl groups through the in situ activation process and then undertake the storage/release of Zn2+. In the activated PTFHQ, the hydroxyl groups and S atoms enlarge the electronegativity region near the electrochemically active carbonyl groups, enhancing their electrochemical activity. Simultaneously, the residual hydroxyl groups could act as hydrophilic groups to enhance the electrolyte wettability while ensuring the stability of the polymer chain in the electrolyte. Also, the Z‐folded structure of PTFHQ plays an important role in reversible binding with Zn2+ and fast ion diffusion. All these benefits make the activated PTFHQ exhibit a high specific capacity of 215 mAh g−1 at 0.1 A g−1, over 3400 stable cycles with a capacity retention of 92 %, and an outstanding rate capability of 196 mAh g−1 at 20 A g−1.

Non‐Metallic NH4+/H+ Co‐Storage in Organic Superstructures for Ultra‐Fast and Long‐Life Zinc‐Organic Batteries

“…Two pairs of voltage plateaus in GCD curves imply a consecutive redox process of OSs cathode (Figure 3a). The vibration bonds of C=O at 1690 cm −1 in FT‐IR spectra gradually weaken to disappear, along with the generation of C−O species at 1421 cm −1 (Figure 3b), interpreting the coordination interaction between carbonyl sites and ionic carriers during discharging [19] . In contrast, −NH− bonds are chemically inert for coupling BF 4 − anions due to the high redox energy barrier (Figure S21).…”

Non‐Metallic NH4+/H+ Co‐Storage in Organic Superstructures for Ultra‐Fast and Long‐Life Zinc‐Organic Batteries

“…The vibration bonds of C=O at 1690 cm À 1 in FT-IR spectra gradually weaken to disappear, along with the generation of CÀ O species at 1421 cm À 1 (Figure 3b), interpreting the coordination interaction between carbonyl sites and ionic carriers during discharging. [19] In contrast, À NHÀ bonds are chemically inert for coupling BF 4…”

Non‐Metal Ion Storage in Zinc‐Organic Batteries

“…[34] Besides, compared with organic small molecules, polymers also display enhanced anti-dissolution and structural robustness due to their covalent structures. [75] However, the twisted molecule chains and random folding traits of polymers often cause difficulties in full utilization of active redoxsites.…”