Synergistic iron ion and alkylammonium cation intercalated vanadium oxide cathode for highly efficient aqueous zinc ion battery

The tunable ion diffusion channel and crystal structure stability play important roles in cathode materials for long-life and high-capacity aqueous zinc-ion batteries (AZIBs). In this work, a promising synergistic intercalated strategy of iron ion and alkylammonium cation is proposed to adjust the layer spacing and stabilize the interlayer crystal structure of vanadium oxide cathode materials for AZIBs. Iron ions as guest species provide strong electrostatic attraction with the negative electricity VOx lattice to stabilize the layered structure. Meanwhile, alkylammonium cation further expands the interlayer spacing and increases the surface hydrophobicity, which is beneficial to increase Zn2+ storage performance and inhibit the dissolution of as-obtained vanadium oxides in aqueous electrolyte. With high structural stability, enhanced layer spacing and surface hydrophobicity, the iron ion and alkylammonium cation co-intercalated vanadium oxide (FeVO-12) offers reversible specific capacity of 408 mAh g−1 at 0.1 A g−1 and an excellent cycling stability with capacity retention of 90% over 1000 cycles at 10 A g−1. This co-intercalation strategy provides a new modus operandi for developing stable and highly efficient vanadium oxide cathode toward AZIBs.