Key Takeaways & Executive Findings
- •• A sustainable protective layer for Zn anodes integrating carbon nanotubes (CNTs) and chitosan via a simple scraping process inhibits dendrite growth and side reactions. • Chitosan's polar functional groups enhance Zn2+ transport, and the even distribution of CNTs lowers local current density, enabling a uniform electric field to regulate Zn deposition. • Benefiting from the chitosan/CNTs protective layer, the Zn//Zn and Zn//V2O5 cells showcase significantly enhanced electrochemical performance, and technical economic analyses demonstrate their practical applications. • The reversibility of chitosan as a binder enables successful recovery of high-value CNTs, demonstrating sustainability and providing a novel design idea for highly efficient use of electrodes.
Abstract
Rechargeable aqueous zinc (Zn)-metal batteries hold great promise for next-generation energy storage systems. However, their practical application is hindered by several challenges, including dendrite formation, corrosion, and the competing hydrogen evolution reaction. To address these issues, we designed and fabricated a composite protective layer for Zn anodes by integrating carbon nanotubes (CNTs) with chitosan through a simple and scalable scraping process. The CNTs ensure uniform electric field distribution due to their high electrical conductivity, while protonated chitosan regulates ion transport and suppresses dendrite formation at the anode interface. The chitosan/CNTs composite layer also facilitates smooth Zn2+ deposition, enhancing the stability and reversibility of the Zn anode. As a result, the chitosan/CNTs @ Zn anode demonstrates exceptional cycling stability, achieving over 3000 h of plating/stripping with minimal degradation. When paired with a V2O5 cathode, the composite-protected anode significantly improves the cycle stability and energy density of the full cell. Techno-economic analysis confirms that batteries incorporating the chitosan/CNTs protective layer outperform those with bare Zn anodes in terms of energy density and overall performance under optimized conditions. This work provides a scalable and sustainable strategy to overcome the critical challenges of aqueous Zn-metal batteries, paving the way for their practical application in next-generation energy storage systems.
1. Introduction
Rechargeable aqueous zinc (Zn)-metal batteries hold great promise for next-generation energy storage systems due to their high theoretical capacity, low cost, and intrinsic safety. However, their practical application is hindered by several challenges, including dendrite formation, corrosion, and the competing hydrogen evolution reaction. These issues lead to poor cycling stability and low Coulombic efficiency, limiting the commercialization of Zn-based batteries.
To address these challenges, various strategies have been explored, such as surface coating, electrolyte optimization, and structural design of Zn anodes. Among these, protective layers have shown effectiveness in regulating Zn deposition and suppressing side reactions. However, many existing coatings rely on polyvinylidene difluoride (PVDF) as a binder, which can increase interfacial impedance and inadequate ion transport due to its hydrophobic nature. Although powder-metallurgy-based and electrodeposition strategies can incorporate carbon nanotubes (CNTs) into zinc anodes without binders, these methods are complex and energy-consuming. Moreover, CNTs recycling is often overlooked. Thus, achieving efficient and recyclable CNTs utilization in zinc anodes remains challenging.
As a natural polymer, chitosan possesses several advantages, such as cost-effectiveness, abundant H-bonded groups, and strong coordination ability. Its abundant hydrogen bonds endow it with excellent self-adhesive properties, allowing it to bind effectively with CNTs without extra binders. More importantly, chitosan's good solubility in acetic acid makes the recycling of CNTs feasible. Inspired by plant cell wall, we develop a sustainable chitosan/CNTs composite protective layer on the zinc anode via a simple and energy-efficient scraping coating method. The chitosan in the composite like a soft matrix not only serves as a binder, but also functions as Lewis basic sites, effectively attracting and capturing Zn2+, thereby regulating Zn2+ transport. Moreover, the CNTs act like the fibrous component, providing strength and conductivity, and the abundant CNTs within the protective layer facilitate the redistribution of charge at the anode interface, which reduces the local current density, resulting in a lower nucleation overpotential for zinc and effectively inhibiting dendrite growth.
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Jinchang Wang, Alessandro Innocenti, Hang Wei, Yuanyuan Zhang, Jingsong Peng, Yuanting Qiao, Weifeng Huang, Jian Liu (2025). Scalable and Sustainable Chitosan/Carbon Nanotubes Composite Protective Layer for Dendrite-Free and Long-Cycling Aqueous Zinc-Metal Batteries. Nano-Micro Letters. https://doi.org/10.1007/s40820-025-01837-7
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Frequently Asked Questions
What is the main challenge addressed in this paper?
The paper addresses the challenges of dendrite formation, corrosion, and hydrogen evolution reaction in aqueous zinc-metal batteries, which hinder their practical application.
How does the chitosan/CNTs protective layer work?
The protective layer integrates carbon nanotubes (CNTs) with chitosan. CNTs ensure uniform electric field distribution due to high conductivity, while protonated chitosan regulates ion transport and suppresses dendrite formation, facilitating smooth Zn2+ deposition.
What are the key performance improvements reported?
The chitosan/CNTs@Zn anode demonstrates exceptional cycling stability, achieving over 3000 hours of plating/stripping with minimal degradation. When paired with a V2O5 cathode, the full cell shows significantly improved cycle stability and energy density.
Is the proposed strategy sustainable?
Yes, the strategy is sustainable because chitosan is a natural polymer that is cost-effective and recyclable. The reversibility of chitosan as a binder enables the successful recovery of high-value CNTs, demonstrating sustainability.
What is the significance of the techno-economic analysis?
The techno-economic analysis confirms that batteries incorporating the chitosan/CNTs protective layer outperform those with bare Zn anodes in terms of energy density and overall performance under optimized conditions, indicating practical applications.
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