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

Abstract

Abstract 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, HNaV 6 O 16 ·4H 2 O‐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 Na 2 V 6 O 16 ·3H 2 O (NVO). Specially, Glu insertion kills three birds with one arrow: i) induces the formation of a structurally stable monoclinic HNaV 6 O 16 ·4H 2 O 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 Zn 2+ diffusion kinetics; moreover, the polar groups on the Glu surface weaken the electrostatic interaction between Zn 2+ 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 Zn 2+ diffusion capability (10 −9 to 10 −7 cm 2 s −1 ) and outstanding cycling stability with a capacity retention of 87.2% after 12 000 cycles at 10 A g −1 .