Self-healing of surface defects on Zn electrode for stable aqueous zinc-ion batteries via manipulating the electrode/electrolyte interphases

Atomic Zincophilic Sites Regulating Microspace Electric Fields for Dendrite-Free Zinc Anode

Aqueous Zn metal batteries are promising candidates for large-scale energy storage due to their intrinsic advantages. However, Zn tends to deposit irregularly and forms dendrites driven by the uneven space electric field distribution near the Zn-electrolyte interphase. Herein it is demonstrated that trace addition of Co single atom anchored carbon (denoted as CoSA/C) in the electrolyte regulates the microspace electric field at the Zn-electrolyte interphase and unifies Zn deposition. Through preferential adsorption of CoSA/C on the Zn surface, the atomically dispersed Co-N3 with strong charge polarization effect can redistribute the local space electric field and regulate ion flux. Moreover, the dynamic adsorption/desorption of CoSA/C upon plating/stripping offers sustainable long-term regulation. Therefore, Zn||Zn symmetric cells with CoSA/C electrolyte additive deliver stable cycling up to 1600 h (corresponding to a cumulative plated capacity of 8 Ah cm-2 ) at a high current density of 10 mA cm-2 , demonstrating the sustainable feature of microspace electric field regulation at high current density and capacity.

Electrolyte and Additive Engineering for Zn Anode Interfacial Regulation in Aqueous Zinc Batteries

Aqueous Zn-metal batteries (AZMBs) have gained great interest due to their low cost, eco-friendliness, and inherent safety, which serve as a promising complement to the existing metal-based batteries, e.g., lithium-metal batteries and sodium-metal batteries. Although the utilization of aqueous electrolytes and Zn metal anode in AZMBs ensures their improved safety over other metal batteries meanwhile guaranteeing their decent energy density at the cell level, plenty of challenges involved with metallic Zn anode still await to be addressed, including dendrite growth, hydrogen evolution reaction, and zinc corrosion and passivation. In the past years, several attempts have been adopted to address these problems, among which engineering the aqueous electrolytes and additives is regarded as a facile and promising approach. In this review, a comprehensive summary of aqueous electrolytes and electrolyte additives will be given based on the recent literature, aiming at providing a fundamental understanding of the challenges associated with the metallic Zn anode in aqueous electrolytes, meanwhile offering a guideline for the electrolytes and additives engineering strategies toward stable AZMBs in the future.

High-Voltage and Stable Manganese Hexacyanoferrate/Zinc Batteries Using Gel Electrolytes

Because of the high safety and environmental friendliness, aqueous zinc-ion batteries have gained a lot of attention in recent years. Prussian blue and its analogues are regarded as a promising cathode material of zinc-ion batteries. Manganese hexacyanoferrate is appropriate among them due to its high operating voltage, large capacity, and cheap price. However, the poor cycling stability of manganese hexacyanoferrate, mainly caused by transition metal dissolution, side reaction, and phase transition, greatly restricts its practical application. In this work, gelatin is used to limit the content of free water in the electrolyte, thus reducing the dissolution effect of transition metal manganese. The introduction of gelatin improves the durability of the Zn anode as well. The optimized MnHCF/gel-0.3/Zn battery displays a high reversible capacity (120 mAh·g^-1 at 0.1 A·g^-1), an excellent rate performance (42.7 mAh·g^-1 at 2 A·g^-1), and a good capacity retention (65% at 0.5 A·g^-1 after 1000 cycles).

Interface engineering strategy construction of covalent organic framework for promoting highly reversible zinc metal

Zn-ion energy storage devices will play important roles in the future energy storage field. However, Zn-ion device development suffers significantly from adverse chemical reactions (dendrite formation, corrosion, and deformation) on the Zn anode surface. Zn dendrite formation, hydrogen evolution corrosion, and deformation combine to degrade Zn-ion devices. Zincophile modulation and protection using covalent organic frameworks (COF) inhibited dendritic growth by induced uniform Zn ion deposition, which also prevented chemical corrosion. The Zn@COF anode circulated stably for more than 1800 cycles even at high current density in symmetric cells and maintained a low and stable voltage hysteresis. This work explains the surface state of the Zn anode and provides information for further research.

Ni-doped Bi2O2CO3 nanosheet with H+/Zn2+ co-insertion for "rocking chair" zinc-ion battery

Developing insertion-type anode is key to advancing "rocking chair" zinc-ion batteries, though there are few reported insertion-type anodes. Herein, the Bi₂O₂CO₃ is a high-potential anode, with a special layered structure. A one-step hydrothermal method was used to prepare Ni-doped Bi₂O₂CO₃ nanosheet, and also a free-standing electrode consisting of Ni-Bi₂O₂CO₃ and CNTs was designed. Both cross-linked CNTs conductive networks and Ni doping improve charge transfer. Ex situ tests (XRD, XPS, TEM, etc.) reveal the H⁺/Zn²⁺ co-insertion mechanism of Bi₂O₂CO₃ and that Ni doping improves its electrochemical reversibility and structural stability. Therefore, this optimized electrode offers a high specific capacity of 159 mAh g^-1 at 100 mA g^-1, a suitable average discharge voltage of ≈0.400 V, and a long-term cycling stability of 2200 cycles at 700 mA g^-1. Besides, the Ni-Bi₂O₂CO₃//MnO₂ "rocking chair" zinc-ion battery (based on the total mass of cathode and anode) delivers a high capacity of ≈100 mAh g^-1 at 50.0 mA g^-1. This work provides a reference for designing high-performance anode in zinc-ion batteries.