Glutamic Acid Induced Proton Substitution of Sodium Vanadate Cathode Promotes High Performance in Aqueous Zinc-Ion Batteries

Lacking strategies to simultaneously address the narrow interlayer spacing, irreversible phase transitions, dissolution and electrical transport issues of vanadium oxides is restricting their application in aqueous zinc-ion batteries. Herein, to address these challenges concurrently, an organic-inorganic hybrid cathode is explored, HNaV6O164H2O-Glu (HNVO-Glu), through a guest material-mediated NVO synthesis strategy utilizing glutamic acid (Glu) to induce Na substituted by proton and enable crystal transformation of Na2V6O163H2O (NVO). Specially, Glu insertion kills three birds with one arrow: i) induces the formation of a structurally stable monoclinic HNaV6O164H2O phase by introducing H into the NVO framework, preventing structural phase change and collapse of NVO material; ii) acts as a pillar to expand the interlayer spacing, which improves the Zn2+ diffusion kinetics; moreover, the polar groups on the Glu surface weaken the electrostatic interaction between Zn2+ and the host materials, further enhancing the zinc-ionic transport rate; iii) enhances the electrical conductivity of HNVO by converting the p-type semiconductor into the n-type semiconductor structure. Consequently, the HNVO-Glu exhibits a high specific capacity (354.6 mAh g-1 at 1 A g-1), excellent Zn2+ diffusion capability (10-9 to 10-7 cm2 s-1) and outstanding cycling stability with a capacity retention of 87.2% after 12 000 cycles at 10 A g-1. Herein, an organic-inorganic hybrid cathode is explored, HNaV6O164H2O-Glu (HNVO-Glu), through a guest material-mediated NVO synthesis strategy utilizing glutamic acid to induce Na substituted by proton and enable crystal transformation of Na2V6O163H2O. Consequently, the HNVO-Glu exhibits a high specific capacity, excellent Zn2+ diffusion capability and outstanding cycling stability with a capacity retention of 87.2% after 12 000 cycles at 10 A g-1. image