Ion‐Specific Acetate‐Mn<sup>2+</sup> Coordination for Accelerating Desolvation Kinetics in Aqueous Mn‐Ion Battery
Lejuan Cai, You‐Ming Zhang, Wenfang Yuan, Jing Cao, Qian Chen, Yingying Lan, Fan Zhang, Yu Zhao, Jian Shang, Wenlong Wang
Abstract
Abstract Aqueous manganese ion batteries (AMIBs) are promising candidates for large‐scale energy storage because of their inherent safety and low cost. As a representative transition metal ion, Mn 2+ features a half‐filled 3d 5 electron configuration that enables diverse coordination geometries and a broader scope for battery optimization. Here, the ion‐specific coordination between Mn 2+ and acetate ions (Ac − ) to adjust the d‐electron configuration of Mn 2+ and induce a distorted water‐deficient hydration shell is demonstrated. The coordination chemistry of Mn 2+ allows Ac − to break the octahedral geometry of [Mn(H 2 O) 6 ] 2+ through ligand exchange, facilitating the de‐solvation kinetics and interfacial transfer of Mn 2+ . This regulating effect is distinct from that observed in Zn 2+ solvation, highlighting the ion‐specific pairing resulting from the d‐electron configurations of transition metals. As expected, incorporating Ac − ligands in aqueous manganese‐based electrolytes enhances the Mn 2+ storage performance of perylenetetracarboxylic diimide (PTCDI) anode in terms of both capacity and stability. An all‐organic AMIB is then assembled by using tetrachloro‐1,4‐benzoquinone (TCBQ) as the cathode, which exhibits an average discharge plateau voltage of 1.1 V, a capacity of 98 mAh g −1 at a current density of 1.0 A g −1 , and an impressive capacity retention of 96.3% over 1000 cycles.