Processable Hydroxide Ink with Oriented Microstructure.

Abstract

The intrinsic poor processability of hydroxide originating from the structural property greatly hinders their practical applications. Here, a processable highly-concentrated nickel/cobalt double hydroxide ink is reported to meet the practical demand. The inner nanoflakes in ink possess a high width/thickness ratio (>100), which endows the highly-concentrated ink (60 mg mL^-1 ) with liquid-like rheology properties. Further, the elliptical diffusive arc in small-angle X-ray scattering pattern and porous and ordered alignment morphology in cryogenic temperature scanning electron microscopy confirms the locally oriented arrangement of nanoflakes in the ink. Benefiting from this interior-ordered structure, the ink can be processed into meter-level film, continuous yarn, and rigid and free-standing aerogel, respectively. In particular, the films can be used as electrodes directly in aqueous zinc ion batteries and deliver a favorable capacity (382 mAh g^-1 @ 200 mA g^-1 ) as well as long cycle stability (capacity retention rate of 88% @ 1000 mA g^-1 after 400 cycles). Moreover, the enlarged-batched fabrication with the introduction of efficient thermal conduction in a 10 L reactor is also carried out successfully. These results clarify the inner relationship between microstructure-rheology and mechanical engineering for hydroxides, thus paving the way to develop hydroxide-based products for future practical applications.