Ion-Molecule Co-Confining Ammonium Vanadate Cathode for High-Performance Aqueous Zinc-Ion Batteries

Vanadium-based cathode materials have attracted great attention in aqueous zinc-ion batteries (AZIBs). However, the inferior ion transport and cyclic stability due to the strong Coulomb interaction between Zn 2+ and the lattice limit their further application. In this work, CO 2 molecules are in situ embedded in the interlayer structure of NH 4 V 4 O 10 by decomposing excess H 2 C 2 O 4 ·2H 2 O in the main framework, obtaining an ion-molecule co-confining NH 4 V 4 O 10 for AZIB cathode material. The introduced CO 2 molecules expanded the interlayer spacing of NH 4 V 4 O 10 , broadened the diffusion channel of Zn 2+ , and stabilized the structure of NH 4 V 4 O 10 as the interlayer pillars together with NH 4 + ${\mathrm{NH}}_4^ + $ , which effectively improved the Zn 2+ diffusion kinetics and cycle stability of the electrode. In addition, the binding between NH 4 + ${\mathrm{NH}}_4^ + $ and the host framework is stabilized via hydrogen bonds with CO 2 molecules. NVO-CO 2 -0.8 exhibited excellent specific capacity (451.1 mAh g −1 at 2 A g −1 ), cycle stability (214.0 mAh g −1 at 10 A g −1 after 1000 cycles) and rate performance. This work provides new ideas and approaches for optimizing vanadium-based materials with high-performance AZIBs.