Zinc (Zn) metal anode suffers from uncontrollable Zn dendrites and parasitic side reactions at the interface, which restrict the practical application of aqueous rechargeable zinc batteries (ARZBs). Herein, an amphoteric cellulose‐based double‐network is introduced as hydrogel electrolyte to overcome these obstacles. On one hand, the amphoteric groups build anion/cation transport channels to regulate electro‐deposition behavior on Zn (002) crystal plane enabled by homogenizing Zn2+ ions flux. On the other hand, the strong bonding between negatively charged carboxyl groups and Zn2+ ions promote the desolvation process of [Zn(H2O)6]2+ to eliminate side reactions. Based on the above two functions, the hydrogel electrolyte enables an ultra‐stable cycling with a cumulative capacity of 7 Ah cm−2 at 20 mA cm−2/20 mAh cm−2 for Zn||Zn cell. This work provides significant concepts for developing hydrogel electrolytes to realize stable anode for high‐performance ARZBs.

Although organic cathode materials with sustainability and structural designability have great potential for rechargeable lithium batteries, the dissolution issue presents a huge challenge to meet the demands of cycling stability and energy density simultaneously. Herein, we have designed and successfully synthesized two novel small-molecule organic cathode materials (SMOCMs) by the same innovative route, namely 7,14-diazabenzo­[a]­tetracene-5,6,8,13-tetraone (DABTTO) and 7,9,16,18-tetraazadibenzo­[a,l]­pentacene-5,6,8,14,15,17-hexaone (TADBPHO). The integrated p-quinone, o-quinone, and pyrazine groups provide these SMOCMs with attractive theoretical capacities of 473 and 568 mAh g–1 based on 6- and 10-electron reactions, respectively, which were almost fully utilized within 0.8–3.8 V vs Li+/Li. The extended aromatic nucleus of TADBPHO makes it much less soluble than DABTTO and thus able to achieve the highest level of cycling stability (66% @ 500th cycle) for SMOCMs in addition to the exceptional energy density (364 mAh g–1 × 2.56 V = 932 Wh kg–1) within 1.5–3.8 V. In addition to the excellent electrochemical performance, the redox reaction and capacity fading mechanisms have been also investigated in detail. The novel approach to construct extended π-conjugated molecules with o-quinone groups is enlightening for the development of high-energy and stable OCMs for future efficient and sustainable energy storage devices.

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Organic cathode materials (OCMs) have been widely applied in aqueous rechargeable zinc batteries (ARZBs), but there are still many novel structures to be explored for better electrochemical performance and clearer mechanism. Herein, we have studied an organic biological dye, namely thionin (Thn‐CH3COO), as a bipolar‐type OCM for ARZBs based on its electroactive phenothiazine unit. In the optimal electrolyte of 2 M Zn(CF3SO3)2, Thn‐CH3COO exhibited the lowest solubility and thus the highest cycling stability (94 % capacity retention after 100 cycles), with a reversible capacity of 162 mAh g−1 (the theoretical value is 186 mAh g−1) and a discharge plateau at ∼0.8 V vs. Zn2+/Zn. Various characterization and DFT calculations have revealed that both CH3COO− and CF3SO3− anions and H+ cations participated the p‐type and n‐type reactions, respectively. In brief, the novel structure, competitive performance, and exhaustive mechanism investigation will facilitate the further development of ARZBs based on OCMs.