Highly Active Granular Nickel Powders for Multi-Batch Production of Spongy Oxide Cathodes

A process was developed for the production of agglomerated carbonyl nickel powders with spherical particles ranging from 45 to 71 μm. The powders are 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 a Superprobe-733 analyzer. The nickel powders were chemically tested to determine their carbon content with automatic coulometric titration by pH values employing an AN-7529U rapid analyzer. The agglomerated carbonyl nickel powders with spherical 45–71 μm particles were produced from PNK-1L5 carbonyl nickel powders 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 agglomerated particles at 400, 500, and 600°C for 0.5 h with intermediate sifting through sieves 071 and 045. Testing of the spongy oxide/nickel cathodes produced in compliance with the agglomeration process for the fine PNK-1L5 nickel powders showed that they could be used to replace the PNK-2K10 nickel powders.