Anion-exchange properties of nickel–aluminum layered double hydroxide prepared by liquid phase deposition

The optimum coordination structure of Ni–fluoro complexes for the preparation of Ni–Al LDH by LPD process and the diverse anion-exchange properties of as-deposited Ni–Al on α-alumina powder were quantitatively evaluated for the industrial application of new positive material for alkali secondary batteries. The [NiF6−x−y(NH3)x(OH−)y]n+ was more suitable than [NiF6]4− as the precursor of the deposition of Ni–Al LDH in the LPD reaction, and the improved LPD reaction achieved the synthesis of high purity and high crystallinity Ni–Al LDH. All anion-exchanged Ni–Al LDHs for OH−–, Cl−–, SO42−–, and CH3COO−–forms kept the high crystallinity and showed the enlargement of interlayer distances. The tilting angle of the intercalated CH3COO− anions was about 15°. Anion-exchange capacity remained constant at a minimum of 0.8 meq g−1 in pH >10, increased as pH decreased, and reached a maximum of 8 meq g−1 at pH 2. Anion-exchange of OH−–form of Ni–Al LDH was accelerated by the neutralization of hydroxide ions in interlayers, in addition, the anion-exchange capacity and the crystallinity of Ni–Al LDH could be controlled by the amount of doped aluminum ions.