Kinetics‐Boosted Effect Enabled by Zwitterionic Hydrogel Electrolyte for Highly Reversible Zinc Anode in Zinc‐Ion Hybrid Micro‐Supercapacitors

Abstract

Despite impressive merits of complementary charge‐storage mechanisms for aqueous Zn‐ion hybrid micro‐supercapacitors (ZHMSCs), it remains a challenge to solve dendrite and parasitic reactions issues of Zn anodes. Herein, a kinetics‐boosted strategy of Zn2+ transport and desolvation of hydrated Zn2+ is proposed by engineering zwitterionic P(AM‐co‐SBMA) hydrogel electrolyte (PASHE) for highly reversible Zn plating/stripping. Mechanically robust and chemically anchored PASHE features zwitterionic groups for constructing ion migration channels and immobilizing water molecules, which accelerates Zn2+ migration for an ultrahigh transfer number (0.84) and alleviates water‐related parasitic reactions. Theoretical calculations combined with experimental results reveal that sulfobetaine sulfonate anions endow PASHE with improved desolvation kinetics and the ability to coordinate Zn2+ flux and electric field distributions at the electrolyte–electrode interface. Thus, Zn anodes exhibit excellent electrochemical performance involving high average coulombic efficiency of 99.4% in Zn|PASHE|Cu cell as well as high cumulative capacity of 2000 mAh cm−2 (20 mA cm−2, 1 mAh cm−2) and depth of discharge of 80.9% (20 mA cm−2, 10 mAh cm−2) in Zn|PASHE|Zn cells. Furthermore, ZHMSCs based on PASHE deliver excellent flexibility and cyclability for energy‐storage applications. This work provides useful insights on hydrogel electrolyte engineering for developing high‐performance Zn anodes and derived energy‐storage devices.

Construction of zwitterionic osmolyte-based hydrogel electrolytes towards stable zinc anode for durable aqueous zinc ion storage and integrated electronics

“…Additionally, new signals located at 1241, 1161, 1030, and 637 cm −1 can be detected, which correspond to the symmetric CF 3 stretching vibration, asymmetric CF 3 stretching vibration, symmetric SO 3 stretching vibration, and asymmetric SO 3 bending of CF 3 SO 3 − anion, respectively. 34–36 The obtained results suggested that the SPS–Zn hydrogel electrolyte was successfully synthesized.…”

All-round supramolecular zwitterionic hydrogel electrolytes enabling environmentally adaptive dendrite-free aqueous zinc ion capacitors

“…[16][17][18][19][20] In particular, their capability to function more effectively in terms of suppressing the growth of Zn-dendrites and undesirable side reactions compared to liquid electrolytes is mainly attributed to the less reactive free water and the robust coordination interaction between Zn 2+ and functional groups in HEs. 17,21,22 Unfortunately, the development of quasi-solid-state ZICs has been hindered by severe interfacial issues. During deep cycling, the mismatch between the static quasi-solid electrolyte surface and the dynamic Zn anode volume change originating from uneven ion diffusion and deposition will lead to inferior interfacial contact, ultimately resulting in a premature failure of the ZICs.…”

“…42 Zwitterions or 'inner salts' represent a unique class of small molecules in which cationic and anionic species are covalently bound, which have been proven to address the key roadblock in electrochemical devices. 22,26,[43][44][45][46][47] For example, Archer et al found that zwitterionic moieties were capable of tuning the Li + -solvation environment at the electrode/electrolyte interface, enabling the compact, planar deposition of lithium metal. 44 Besides, Pringle et al demonstrated that zwitterion-based electrolytes enabled high target ion transport and supported stable lithium metal cell cycling.…”

“…43 Critically, the benefits of zwitterions as self-adhesive and self-healing hydrogel electrolytes for flexible Zn-based electrochemical devices include enhanced interfacial stability, increased target ion transport and ionic conductivity, and improved stability against Zn metal. 22,26,[46][47][48] To the best of our knowledge, despite the wide range of properties and potential uses of HEs reported to date, their value in overcoming the challenges in developing all-around supramolecular zwitterionic hydrogel electrolytes for dendrite-free devices such as ZICs has not been explored to date.…”

Deposition behavior regulated by an SPSF@PMIA nanofiber separator for high-performance zinc ion batteries

“…The voltage gaps of Zn/SPSF/Ti and Zn/PMIA/Ti cells increase gradually as the number of cycles increases, which confirmed the continuous growth of zinc dendrites. 45,46 Impressively, the Zn/SP/Ti cell not only exhibits a high initial CE of 94.1% and low voltage hysteresis (69.8 mV), but also a significant improvement in cycle life, maintaining a stable voltage gap after 400 cycles. The CEs of Zn–Ti half-cells are displayed in Fig.…”