Design of Layer Structure Metal Oxide Material with Dual-Ion Defects for High-Performance Aqueous Zn Ion Batteries

Abstract

Layer structure metal oxides are promising energy storage materials for rechargeable batteries. However, they are still hindered by insufficient ion storage sites and sluggish ion diffusion kinetics during ion insertion/extraction, leading to unsatisfactory battery performance. Herein, we have successfully designed layer structure metal oxides with regulated dual-ion defects via the ion exchange and annealing processes. As for demonstration, a K iv TO ev @Ti anode with dual-ion defects by incorporating with the interlaminar K vacancies and layer edge O vacancies in layer structure potassium titanate (KTO) was synthesized for Zn ion batteries. The bionic defects in the K iv TO ev @Ti anode are indicated to provide extra space for potent Zn ion storage and enhance the Zn ion diffusion rate. Complete inner layer structure and residual interlayer K ion pillars ensure that the K iv TO ev @Ti anode has highly structural stability and reversible electrochemistry. Therefore, K iv TO ev @Ti delivers a favorable Zn ion storage capability of 179.2 mAh g – 1 at 0.05 A g –1, and a remarkable cycling stability of 82% capacity retention after 5000 cycles at 0.5 A g –1 . The Zn x MnO 2 //K iv TO ev @Ti full cell presents an excellent power/energy density of 583.5 W kg –1 /97.8 Wh kg –1, respectively, and maintains a capacity retention of 90% after 5000 cycles. This work can enlighten material engineering for energy storage area.