Restraining growth of Zn dendrites by poly dimethyl diallyl ammonium cations in aqueous electrolytes

Metallic zinc is an excellent anode material for Zn-ion batteries, but the growth of Zn dendrite severely hinders its practical application. Herein, an efficient and economical cationic additive, poly dimethyl diallyl ammonium (PDDA) was reported, used in aqueous Zn-ion batteries electrolyte for stabilizing Zn anode. The growth of zinc dendrites can be significantly restrained by benefiting from the pronounced electrostatic shielding effect from PDDA on the Zn metal surface. Moreover, the PDDA is preferentially absorbed on Zn (002) plane, thus preventing unwanted side reactions on Zn anode. Owing to the introduction of a certain amount of PDDA additive into the common ZnSO₄-based electrolyte, the cycle life of assembled Zn||Zn cells (1 mA·cm⁻² and 1 mAh·cm⁻²) is prolonged to more than 1100 h. In response to the perforation issue of Zn electrodes caused by PDDA additives, the problem can be solved by combining foamy copper with zinc foil. For real application, Zn-ion hybrid supercapacitors and MnO₂||Zn cells were assembled, which exhibited excellent cycling stability with PDDA additives. This work provides a new solution and perspective to cope with the dendrite growth problem of Zn anode.