Gandhi Rustam K, Manning Sydney, Zheng J X Kent
Department of Chemical Engineering, University of Texas at Austin Austin Texas 78712 USA
Texas Materials Institute, University of Texas at Austin Austin Texas 78712 USA.
Chem Sci. 2025 Aug 29. doi: 10.1039/d5sc04189a.
Functional additives are widely used in electrochemical systems to guide metal deposition and suppress unfavorable porous growth modes. A key strategy involves adding secondary metal cations with higher redox potentials, which spontaneously undergo ion exchange and deposit as an interfacial alloying layer to promote uniform growth during battery recharge. However, we discover that in the absence of kinetic control, this electroless deposition of the alloying layer unexpectedly induces dendritic growth due to local ion depletion, especially when additive concentrations are low. Contrary to conventional wisdom, free additive cations can therefore destabilize-rather than stabilize-metal anode interfaces. To overcome this, we introduce a chelation-based approach that regulates the release of additive cations and smooths interfacial deposition. Using Cu additives and EDTA chelators in aqueous Zn batteries as a model system, we demonstrate that chelation enables controlled Cu release, forming uniform interfacial layers and remarkably improving cycling stability. The chelation-regulated system achieves >99% Zn reversibility and 2-3× longer cycle life under practical current densities and capacities (, 1 mAh cm at 10 mA cm, and 10 mAh cm at 10 mA cm), while unregulated systems fail rapidly. Extension of the controlled release framework to systems beyond the Cu-EDTA pair is also demonstrated. This work highlights the importance of molecular-level control over additive reactivity and offers a generalizable strategy for stabilizing metal anodes in energy-dense batteries.
功能添加剂广泛应用于电化学系统中，以引导金属沉积并抑制不利的多孔生长模式。一个关键策略是添加具有较高氧化还原电位的二次金属阳离子，这些阳离子会自发地进行离子交换并沉积为界面合金层，以促进电池充电过程中的均匀生长。然而，我们发现，在缺乏动力学控制的情况下，由于局部离子耗尽，这种合金层的无电沉积意外地会引发枝晶生长，尤其是当添加剂浓度较低时。与传统观念相反，游离的添加剂阳离子因此会使金属阳极界面不稳定，而不是使其稳定。为了克服这一问题，我们引入了一种基于螯合的方法，该方法可调节添加剂阳离子的释放并使界面沉积更加平滑。在水系锌电池中使用铜添加剂和乙二胺四乙酸（EDTA）螯合剂作为模型系统，我们证明螯合能够实现可控的铜释放，形成均匀的界面层，并显著提高循环稳定性。在实际电流密度和容量下（10 mA cm² 时为 1 mAh cm⁻²，10 mA cm² 时为 10 mAh cm⁻²），螯合调节的系统实现了 >99% 的锌可逆性和 2 - 3 倍的循环寿命，而未调节的系统则迅速失效。还展示了将控释框架扩展到除铜 - EDTA 对之外的系统。这项工作突出了对添加剂反应性进行分子水平控制的重要性，并为在能量密集型电池中稳定金属阳极提供了一种可推广的策略。
