Highly active granular nickel powders for multibatch production of spongy oxide cathodes

Abstract

A process was developed for the production of agglomerated carbonyl nickel powders with spherical particles ranging from 45 to 71 μm, intended to make spongy oxide/nickel cathodes. The idea relied on the separation of integral and local compaction effects in the sintering of agglomerated powders. The morphology and particle size of the powders were examined by scanning electron microscopy using Superprobe-733 analyzer. Chemical analysis of the nickel powders on carbon was carried out with automatic coulometric titration by рН values employing an AN-7529U rapid analyzer. The agglomerated carbonyl nickel powder with spherical particles ranging from 45 to 71 μm was produced from powders of PNK-1L5 carbonyl nickel with average particle sizes of 4 μm by annealing without mechanical grinding. The optimum process of producing nickel powders with 45–71 μm particles involves stage-by-stage annealing of preliminary agglomerated particles at 400, 500, and 600 °С for 0.5 h with intermediate sifting through sieves 071 and 045. Testing of spongy oxide/nickel cathodes produced in compliance with the agglomeration process for fine PNK-1L5 nickel powders showed that they could be used to replace PNK-2K10 nickel powders.