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−1cathode at 7.87 kW kg−1cathode, exhibiting the high energy and high power simultaneously. All these results indicate the promising potential of this composite in rechargeable aqueous batteries.