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.