Alkaline zinc-based flow batteries (AZFBs) have emerged as a promising electrochemical energy storage technology owing to Zn abundance, high safety, and low cost. However, zinc dendrite growth and the formation of dead zinc greatly impede the development of AZFBs. Herein, a dual-function electrolyte additive strategy is proposed to regulate zinc nucleation and mitigate the hydroxide corrosion of zinc depositions for stable AZFBs. This strategy, as exemplified by urea, introduces an electrolyte additive to coordinate with Zn²⁺/Zn with proper strength, slowing zinc deposition kinetics to induce uniform nucleation and protecting the deposited zinc surface from attack by hydroxide ions through preferable adsorption. The zincate complexes with urea are identified to be Zn(OH)₂(urea)(H₂O)₂ and Zn₂(OH)₄(H₂O)₄(urea), which exhibit slow zinc deposition kinetics, allowing instantaneous nucleation. Calculation results reveal an additional energy barrier of 1.29 eV for the subsequent adsorption of an OH⁻ group when a urea molecule absorbs on the zinc cluster, significantly mitigating the formation of dead zinc. Consequently, prolonged cell cycling of the prototype alkaline zinc-iron flow battery demonstrates stable operation for over 130 h and an average coulombic efficiency of 98.5%. It is anticipated that this electrolyte additive strategy will pave the way for developing highly stable AZFBs.

中文翻译：

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用于长寿命碱性锌液流电池的双功能电解质添加剂设计

碱性锌基液流电池（AZFB）由于锌含量丰富、安全性高、成本低而成为一种有前途的电化学储能技术。然而，锌枝晶的生长和死锌的形成极大地阻碍了AZFB的发展。在此，提出了一种双功能电解质添加剂策略来调节锌成核并减轻锌沉积物的氢氧化物腐蚀，以获得稳定的AZFB。以尿素为例，该策略引入电解质添加剂以适当的强度与Zn ²⁺ /Zn配位，减缓锌沉积动力学以诱导均匀成核，并通过更好的吸附保护沉积的锌表面免受氢氧根离子的攻击。锌酸盐与尿素的络合物被鉴定为 Zn(OH) ₂ (尿素)(H ₂ O) ₂和 Zn ₂ (OH) ₄ (H ₂ O) ₄ (尿素)，它们表现出缓慢的锌沉积动力学，允许瞬时成核。计算结果表明，当尿素分子吸附在锌簇上时，后续吸附 OH ^-基团时会产生 1.29 eV 的额外能垒，从而显着减少死锌的形成。因此，原型碱性锌铁液流电池的长期电池循环表现出稳定运行超过 130 小时，平均库伦效率为 98.5%。预计这种电解质添加剂策略将为开发高度稳定的 AZFB 铺平道路。