Simultaneous extraction and separation of Ni(OH)2, Ni powder and Ni plate from waste nickel-cobalt scrap in one spot: Control sequence of electrical reduction

Abstract

Extracting valuable metals from waste lithium-ion batteries is beneficial to the long-term growth of social economy and environmental maintenance from lithium-ion batteries, yet it faces serious challenges. The study aims to propose a harmless and efficient electrolysis method for selectively preparing nickel products from lithium-ion batteries leachate by controlling the competitive reductive order for Ni2+ and H2O. Compared with current pyrometallurgy, hydrometallurgy, and bio-metallurgy methods, electrolysis method allows selective preparation of different nickel products. No additional chemicals are introduced, or no membrane limitation. Achieving zero pollution emissions while saving costs. The results of serial experiments show that the level of nickel reduction can be controlled to produce different types of nickel products. The current efficiency reached a maximum value of 84.7±4.5%. 125 A/m2, 0.05 M Ni2+, 1.5 h, 60 A/m2, 0.1 M Ni2+, 2 h, 125 A/m2, 0.25 M Ni2+, 2 h are the optimal conditions for forming Ni(OH)2, black powder Ni and silvery flake Ni, respectively. In electrolysis process, selective nickel products, H2 and O2 can be prepared. H2 can be used as clean energy and increases economic benefits. This study provides a clean and high-efficiency method for selectively preparing nickel products from lithium-ion batteries leachate.