In Situ Self-Reconfiguration Induced Multifunctional Triple-Gradient Artificial Interfacial Layer toward Long-Life Zn-Metal Anodes.

Aqueous Zn-ion batteries featuring with intrinsic safety and low cost are highly desirable for large-scale energy storage, but the unstable Zn-metal anode resulting from uncontrollable dendrite growth and grievous hydrogen evolution reaction (HER) shortens their cycle life. Herein, a feasible in situ self-reconfiguration strategy is developed to generate triple-gradient poly(diallyldimethylammonium) bis(trifluoromethanesulfonyl)imide (PDDA-TFSI)-Zn5(OH)8Cl2·H2O-Sn (PT-ZHC-Sn) artificial layer. The resulting triple-gradient interface consists of the spherical top layer PT with cation confinement and H2O inhibition, the dense intermediate layer ZHC nanosheet with Zn2+ conduction and electron shielding, and the bottom layer Znophilic Sn metal. The well-designed triple-gradient artificial interfacial layer synergistically facilitates rapid Zn2+ diffusion to regulate uniform Zn deposition and accelerates the desolvation process while suppressing HER. Consequently, the PT-ZHC-Sn@Zn symmetric cell achieves an ultralong lifespan over 6500 h at 0.5 mA cm-2 for 0.5 mAh cm-2. Furthermore, a full battery coupling with MnO2 cathode exhibits a 17.2% increase in capacity retention compared with bare Zn anode after 1000 cycles. The in situ self-reconfiguration strategy is also applied to prepare triple-gradient PT-ZHC-In, and the assembled Zn//Cu cell operates steadily for over 8400 h while maintaining Coulombic efficiency of 99.6%. This work paves the way to designing multicomponent gradient interface for stable Zn-metal anodes.

Molecular Engineering Enables Hydrogel Electrolyte with Ionic Hopping Migration and Self-Healability toward Dendrite-Free Zinc-Metal Anodes.

Hydrogel electrolytes (HEs), characterized by intrinsic safety, mechanical stability, and biocompatibility, can promote the development of flexible aqueous zinc-ion batteries (FAZIBs). However, current FAZIB technology is severely restricted by the uncontrollable dendrite growth arising from undesirable reactions between the HEs with sluggish ionic conductivity and Zn metal. To overcome this challenge, this work proposes a molecular engineering strategy, which involves the introduction of oxygen-rich poly(urea-urethane) (OR-PUU) into polyacrylamide (PAM)-based HEs. The OR-PUU/PAM HEs facilitate rapid ion transfer through their ionic hopping migration mechanism, resulting in uniform and orderly Zn2+ deposition. The abundant polar groups on the OR-PUU molecules in OR-PUU/PAM HEs break the inherent H-bond network, tune the solvation structure of hydrated Zn2+, and inhibit the occurrence of side reactions. Moreover, the interaction of hierarchical H-bonds in the OR-PUU/PAM HEs endows them with self-healability, enabling in situ repair of cracks induced by plating/stripping. Consequently, Zn symmetric cells incorporating the novel OR-PUU/PAM HEs exhibit a long cycling life of 2000 h. The resulting Zn-MnO2 battery displays a low capacity decay rate of 0.009% over 2000 cycles at 2000 mA g-1. Overall, this work provides valuable insights to facilitate the realization of dendrite-free Zn-metal anodes through the molecular engineering of HEs.

In Situ Etching of Multifunctional Three-Dimensional Interfacial Layers for the Construction of Porous Zn Anodes with Enhanced Surface Textures.

Aqueous Zn-ion batteries offer the advantages of greater security and lower fabrication costs over their lithium-ion counterparts. However, their further advancement and practical application are hindered by the drastic decay in their performance due to the uncontrollable dendrite growth on Zn anodes. In this study, we fabricated a versatile three-dimensional (3D) interfacial layer (3D PVDF-Zn(TFO)2 (PVDF: poly(vinylidene fluoride); TFO: trifluoromethanesulfonate), which simultaneously formed porous Zn-metal anodes (PZn) with an enhanced (002) texture, via a in situ etching scheme. The 3D PVDF-Zn(TFO)2@PZn symmetrical cells leverage the advantages of surface coating and 3D porous architectures to yield extra-long cyclic lifetimes of over 5300 h (0.1 mA cm-2). The fabricated anodes were found to be compatible with MnO2 cathodes, and the resulting full batteries delivered an outstanding capacity of 336 mAh g-1 at 0.1 A g-1 and exhibited impressive long-term reversibility with a capacity retention of 78.7% for 2000 cycles. The proposed coating strategy is viable for developing porous structures with cutting-edge designs and for textured surface engineering.