A novel 3-phenylpropylamine intercalated molecular bronze with ultrahigh layer spacing as a high-rate and stable cathode for aqueous zinc-ion batteries

Abstract

Rechargeable aqueous zinc-ion batteries (AZIBs) have gained increasing attention owing to their low cost and high safety. Although hydrated vanadium oxides exhibit rich redox chemistry and open layer architecture, the insertion of multivalent Zn2+ during cycling inevitably leads to host collapse and severe vanadium dissolution. Accordingly, various ions and conducting polymers have been introduced into the interlayer to produce vanadium bronzes with a robust crystal structure. However, these pre-intercalated vanadium bronzes demonstrate limited improvement and still face the challenge of metal ion displacement and confusing reaction mechanisms. Herein, we report a novel molecular bronze with intercalated 3-phenylpropylamine for use as an AZIB cathode, which produces an ultrahigh interlayer of 18.0 Å. The cathode delivered an improved capacity of 420 mAh g−1 at 0.1 A g−1, an impressive rate capability of 158 mAh g−1 at 35 A g−1, and an outstanding lifespan with a capacity retention of 94% over 1200 cycles at 2A g−1. Furthermore, the reaction mechanism of H+/Zn2+ co-insertion was investigated in detail. This work proves that this strategy is universal for vanadium oxide bronzes and opens a new avenue for the fabrication of novel molecular bronzes as advanced AZIB cathodes.