3D Printed Free‐Standing Na ₃ V ₂ (PO ₄ ) ₂ F ₃ Cathode With Grid Structure for Highly Bendable Aqueous Zinc Ion Battery

ABSTRACT Flexible aqueous zinc‐ion batteries (AZIBs) have gained significant attention as an ideal choice for flexible batteries with eco‐friendliness, portability, and high safety. 3D printing significantly improves the porosity and ion diffusion efficiency of the electrode through precise microstructure control, while reducing the weight of the electrode. Herein, a 3D printed free‐standing Na ₃ V ₂ (PO ₄ ) ₂ F ₃ (3DP‐NVPF) cathode with a grid structure is designed. The flexible self‐supporting cathode delivers a discharge capacity of 91.2 mAh g ⁻¹ with a high working potential of 1.6 V at 0.1 A g ⁻¹ , along with good cycling performance (capacity cycle loss is only 0.029% at 0.5 A g ⁻¹ during 500 cycles) and rate capability. Furthermore, the freestanding cathode, by eliminating the current collector, implies a higher capacity of the whole electrode (29.8 mAh g ⁻¹ at 0.5 A g ⁻¹ ), compared to most reported phosphate electrodes. Particularly, the highly bendable pouch battery can work well at various fixed bending angles (30°, 90°, 180°) conditions ascribed to the bending‐tolerant cathode and shows quite stable electrochemical performance during 100 times bending, which demonstrates its potential application in flexible and wearable electronics.