Challenges and protective strategies on zinc anode toward practical aqueous zinc‐ion batteries

As a promising energy storage device, an aqueous zinc ion battery (AZIB) still suffers dendrite growth, hydrogen evolution, and corrosion. Hydrogel electrolyte solves the above issues to some extent. Nevertheless, the mechanical properties of most hydrogel electrolytes are not competitive enough to meet booming demand for flexible electronics. In this work, a robust “chain‐gear” hydrogel electrolyte (PM‐HE) crosslinked by polymeric micelles (PMs) is constructed, in which PMs serve as “gears” and form “chain‐gear” structure with polyanion chains. Specifically, “gears” support molecular chains, constructing hierarchically porous structures and opening up paths for Zn2+. Apart from as crosslinkers, PMs exist competitive mechanism with polyanion chains to promote ion decoupling. Such a “chain‐gear” structure can realize desolvation and accelerate ion transport. Thereby, PM‐HE possesses excellent ionic conductivity (60.6 mS cm−1) and ultrahigh transference number (0.88). Symmetrical cells can realize stable cycling over 1500 h with Zn uniform deposition. Remarkably, PM‐HE has excellent tensile (0.23 MPa) and compressive (11.3 MPa) properties profited from strengthening and toughening effect of PMs. The flexible battery can supply power stably under harsh conditions. This work proposes the strategy of constructing an all‐around hydrogel electrolyte based on reasonable design in network structure, providing more possibilities for the practical application of flexible AZIB.

A Robust Hydrogel Electrolyte with Ultrahigh Ion Transference Number Derived from Zincophilic “Chain‐Gear” Network Structure for Dendrite‐Free Aqueous Zinc Ion Battery

Sun,

Ji,

et al. 2024

Dual‐Functional LiCl Additive for Highly Reversible Zinc Metal Anode

Song,

Liu,

Long

et al. 2024

Zinc metal has emerged as a promising candidate for high‐capacity and low‐cost anodes in aqueous zinc‐ion batteries; nevertheless, it encounters serious obstacles, including low cycling stability and poor reversibility, caused by parasitic reactions and the formation of zinc dendrites. Herein, the study proposes a novel nonprotonic dimethylacetamide (DMAC)/ZnCl2/LiCl electrolyte that enables both solvation structural modulation of [ZnClx]2‐x and the cationic electrostatic shielding effect of [Li(DMAC)]+ by controlling the concentration of LiCl. The optimal concentration of LiCl electrolyte (0.28 m), which results in the highest ratio of [ZnCl3]−, strikes a balance between low desolvation energy and a high mass transfer rate while promoting homoepitaxial deposition of Zn (002). Moreover, inert [Li(DMAC)]+ ions, which possess a lower reduction potential, preferentially adsorb onto zinc protrusions, mitigating the tip effect. Leveraging electrolyte engineering, the zinc deposition/stripping process results in impressive long‐term stability, surpassing 2,800 cycles, and the Zn||MnO2 cell also achieves a stable lifespan extending beyond 1400 cycles. The research highlights the potential of LiCl as an additive in the modulation of water‐free electrolytes.

Zincophilic Design for Highly Stable and Dendrite‐Free Zinc Metal Anodes in Aqueous Zinc‐Ion Batteries

Zhang,

Mao,

Xia

et al. 2024

Aqueous zinc‐ion batteries represent a highly promising next‐generation electrochemical energy storage system because of their safety, environmental friendliness, resource abundance, and simple assembly conditions. However, the formation and growth of zinc dendrites on zinc anode seriously hinder the practical application of zinc‐ion batteries. Zincophilic design, which enables the uniform zinc nucleation/deposition, offers an effective solution to achieve dendrite‐free zinc anodes. Despite significant progress in the field of zincophilic design, the research in this field currently lacks clear analysis and guidance. This paper provides a comprehensive overview of the current research status of zincophilic design and the mechanism for dendrite‐free zinc anode from three aspects: construction of zinc anode zincophilic layers, addition of zincophilic additives in electrolyte, and construction of 3D zincophilic host. Moreover, the challenges facing the industrialization and commercialization of zinc‐ion batteries in the further are briefly discussed.