Creatinine: A Muscle Metabolite as a Multifunctional Electrolyte Additive for Aqueous Zinc‐Ion Batteries

Abstract Aqueous zinc‐ion batteries (AZIBs) have demonstrated considerable potential for utilization in large‐scale energy storage applications, driven by their environmental sustainability, inherent safety and cost‐effectiveness. Nonetheless, the growth of Zn dendrites and side reactions, resulting in degraded cycling stability, poses a substantial obstacle to the practical implementation of AZIBs. Herein, it is demonstrated that creatinine (Cre), a metabolite derived from muscle, serves as a multifunctional electrolyte additive that enhances the performance of AZIBs. Both experimental and theoretical analyses reveal that Cre, when used as an electrolyte additive, fulfills three key roles: it disrupts the solvation structure of Zn 2+ by carbonyl group; it forms a water‐deficient electric double layer, thereby reducing the likelihood of interfacial water decomposition; and it promotes the deposition of Zn 2+ on the (002) planes, facilitating the uniform deposition. The Zn||Zn symmetric cell utilizing a 1 M ZnSO 4 electrolyte with the addition of 0.3 M Cre exhibits stable cycling for 900 h under the condition of 1 mA cm −2 and 1 mAh cm −2 , representing an over 11‐fold increase in lifespan. Furthermore, the Zn||VO 2 full cell demonstrates a capacity retention of ≈105 mAh g −1 after 300 cycles at a rate of 10 C.