Truncated cobalt hexacyanoferrate nanocubes threaded by carbon nanotubes as a high-capacity and high-rate cathode material for dual-ion rechargable aqueous batteries.

Abstract Prussian blue (PB) and its analogues (PBAs) have been regarded as one of promising electrode candidates in aqueous batteries, due to its open framework, robust skeleton, and simple preparation protocol. However, intrinsic structure vacancies and poor electron conductivity lower their electrochemical performances, particularly in terms of reversible capacity, rate capability, and cycling stability. Here, truncated cobalt hexacyano-ferrate nanocubes threaded by carbon nanotubes are synthesized with the assistances of citrate and glycerol. The low content of structure vacancies in cobalt hexacyanoferrate, and the intimate contact between it and carbon nanotubes, well address the above issues, resulting in excellent performances in rechargeable aqueous batteries. The reversible capacity reaches 107.2 mAh g−1 at 0.1 A g−1, 87.3% of which is kept at 5 A g−1. After paired with Zn foil as a dual-ion full cell, it delivers a high energy of 107.1 Wh kg−1 cathode at 7.87 kW kg−1 cathode , exhibiting the high energy and high power simultaneously. All these results indicate the promising potential of this composite in rechargeable aqueous batteries. Highlights • Truncated cobalt hexacyanoferrate nanocubes are threaded by carbon nanotubes. • This composite shows reduced structure vacancies and enhanced conductivity. • The specific capacity reaches 107.2 mAh g−1 at 0.1 A g−1 and 95 mAh g−1 at 5 A g−1. • This composite is paired with Zn for dual-ion aqueous batteries. • Full cells deliver an energy density of 107.1 Wh kg−1 at 7.87 kW kg−1. Graphical abstract Image 1 [ABSTRACT FROM AUTHOR]