Constructing highly safe and long‐life calcium ion batteries based on hydratedvanadium oxide cathodes featuring a pillar structure
Chunfang Wang, Shiwei Zhang, Lan Huang, Yuanmin Zhu, Feng Liu, Jianchuan Wang, Liming Tan, Chunyi Zhi, Cuiping Han
Abstract
Abstract Calcium‐ion batteries (CIBs) have generated intense interest due to the growing demand for safer, cheaper, and large‐scale energy storage systems. However, their development is still in its infancy, owing to the lack of suitable cathodes for sustaining reversible Ca 2+ intercalation/deintercalation. Herein, layered H 2 V 3 O 8 (HVO) with Zn 2+ pre‐insertion (ZHVO) is reported as a high‐rate and highly durable cathode material for CIBs. The existence of Zn 2+ and H 2 O pillars could expand the interlayer spacing up to 1.8 nm, which is favorable for the diffusion of bulky Ca 2+ . The formation of Zn–O bonds facilitates electron transfer and enhances electrical conduction. Consequently, the ZHVO cathode achieves superior capacity performance (213.9 mAh·g −1 at 0.2 A·g −1 ) and long lifespan (78.3% for 1,000 cycles at 5 A·g −1 ) compared to pristine HVO. Density functional theory (DFT) calculations revealed that Zn 2+ moved during Ca 2+ intercalation, thereby reducing the diffusion energy barrier and facilitating Ca 2+ diffusion. Finally, a safe aqueous calcium ion cell was successfully assembled.