A dendrite-free anode for stable aqueous rechargeable zinc-ion batteries

Recent advances in electrospinning nanofiber materials for aqueous zinc ion batteries

Aqueous zinc ion batteries (AZIBs) are regarded as one of the most promising large-scale energy storage systems because of their considerable energy density and intrinsic safety. Nonetheless, the severe dendrite growth of the Zn anode, the serious degradation of the cathode, and the boundedness of separators restrict the application of AZIBs. Fortunately, electrospinning nanofibers demonstrate huge potential and bright prospects in constructing AZIBs with excellent electrochemical performance due to their controllable nanostructure, high conductivity, and large specific surface area (SSA). In this review, we first briefly introduce the principles and processing of the electrospinning technique and the structure design of electrospun fibers in AZIBs. Then, we summarize the recent advances of electrospinning nanofibers in AZIBs, including the cathodes, anodes, and separators, highlighting the nanofibers' working mechanism and the correlations between electrode structure and performance. Finally, based on insightful understanding, the prospects of electrospun fibers for high-performance AZIBs are also presented.

Rationalized Electroepitaxy toward Scalable Single-Crystal Zn Anodes

Electroepitaxy is recognized as an effective approach to prepare metal electrodes with nearly complete reversibility. Nevertheless, large-scale manipulation is still not attainable owing to complicated interfacial chemistry. Here, the feasibility of extending Zn electroepitaxy toward the bulk phase over a mass-produced mono-oriented Cu(111) foil is demonstrated. Interfacial Cu-Zn alloy and turbulent electroosmosis are circumvented by adopting a potentiostatic electrodeposition protocol. The as-prepared Zn single-crystalline anode enables stable cycling of symmetric cells at a stringent current density of 50.0 mA cm^-2 . The assembled full cell further sustaines a capacity retention of 95.7% at 5.0 A g^-1 for 1500 cycles, accompanied by a controllably low N/P ratio of 7.5. In addition to Zn, Ni electroepitaxy can be realized by using the same approach. This study may inspire rational exploration of the design of high-end metal electrodes.

A strategy for anode modification for future zinc-based battery application

In the past several years, rechargeable zinc batteries, featuring the merits of low cost, environmental friendliness, easy manufacturing, and enhanced safety, have, attracted much attention. Zinc (Zn) anodes for zinc metal batteries play an important role. In this review, the fundamental understanding of these batteries and modification strategies to deal with the problematic issues for Zn anodes, including dendrite growth, corrosion, and the hydrogen evolution phenomenon will be summarized. The practical application of Zn anodes can still lead to Zn dendrites, various side reactions, and serious safety risks. Therefore, metal-free anodes for "rocking chair" zinc ion batteries to replace Zn anodes are systemically reviewed. The performance and the zinc storage mechanism of metal-free anodes will be discussed. Subsequently, a "rocking chair" zinc ion battery prototype selected as a recent example is assessed to explore the merits and demerits of Zn anodes and metal-free anodes. To conclude, a perspective on the future of zinc metal batteries and "rocking chair" zinc ion batteries is presented. It is hoped that this review may provide for further improvement of commercial rechargeable zinc batteries.

Inhibition of Zinc Dendrites Realized by a β-P(VDF-TrFE) Nanofiber Layer in Aqueous Zn-Ion Batteries

Uncontrollable Zn dendrite formations and parasitic side reactions on Zn electrodes induce poor cycling stability and safety issues, preventing the large-scale commercialization of Zn-ion batteries. Herein, to achieve uniform Zn deposition and suppress side reactions, an electrospun ferroelectric poly(vinylidene fluoride-co-trifluoroethylene) copolymer, a P(VDF-TrFE) nanofiber layer, is introduced as an artificial solid-electrolyte interface on a Cu substrate acting as a current collector. The aligned molecular structure of β-P(VDF-TrFE) can effectively suppress localized current density on the Cu surface, lead to uniform Zn deposition, and suppress side reactions by preventing direct contact between electrodes and aqueous electrolytes. The half-cell configuration formed by the newly fabricated electrode can achieve an average coulombic efficiency of 99.2% over 300 cycles without short-circuiting at a current density of 1 mA cm-2 and areal capacity of 1 mAh cm-2. Stable cycling stability is also maintained for 200 cycles at a current density of 0.5 A g-1 in a full-cell test using MnO2 as a cathode.