Degradation Mechanism of Nickel-Cobalt-Aluminum (NCA) Cathode Material from Spent Lithium-Ion Batteries in Microwave-Assisted Pyrolysis

Abstract

Recycling of Li-Ion Batteries (LIBs) is still a topic of scientific interest. Commonly, spent LIBs are pretreated by mechanical and/or thermal processing. Valuable elements are then recycled via pyrometallurgy and/or hydrometallurgy. Among the thermal treatments, pyrolysis is the most commonly used pre-treatment process. This work compares the treatment of typical cathode nickel-cobalt-aluminum (NCA) material by conventional pyrolysis, and by a microwave assisted pyrolysis. In the conventional route, the heating is provided indirectly, while via microwave the heating is absorbed by the microwaves, according to the materials properties. The comparison is done with help of a detailed characterization of solid as well as the gaseous products during and after the thermal treatment. The results indicated at least three common stages in the degradation: Dehydration and evaporation of electrolyte solvents (EC) and two degradation periods of EC driven by combustion and reforming reactions. In addition, microwave assisted pyrolysis promotes catalytic steam and dry reforming reactions, leading to the strong formation of H2 and CO.

Recycling of Lithium‐Ion Batteries—Current State of the Art, Circular Economy, and Next Generation Recycling

“…[114,117,[119][120][121][122] In comparison, in an oxygen-free environment pyrolysis allows the transformation of the organic compounds into lower molecular compounds or their recovery by recondensation. [123] Further literature reports the separation of current collector foils and active material by pyrolysis. [124][125][126]…”

The Effects of Gas Saturation of Electrolytes on the Performance and Durability of Lithium‐Ion Batteries

“…Here, a range of different gases is formed [see Eqs. (1)–(6)] [12–18] . These reactions are desired to a certain degree, since they result in the formation of the solid electrolyte interphase (SEI) which is a protective layer that covers the negative electrode surface and ensures reversible intercalation of lithium ions into the graphite electrode while preventing further electrolyte degradation [19–25] .…”

“…(1)–(6)]. [ 12 , 13 , 14 , 15 , 16 , 17 , 18 ] These reactions are desired to a certain degree, since they result in the formation of the solid electrolyte interphase (SEI) which is a protective layer that covers the negative electrode surface and ensures reversible intercalation of lithium ions into the graphite electrode while preventing further electrolyte degradation. [ 19 , 20 , 21 , 22 , 23 , 24 , 25 ] The formation of important SEI components, such as lithium alkyl carbonates [e. g., LEDC; Eq.…”

Sustainable Utilization of Metals-Processing, Recovery and Recycling

“…Consumer and production wastes show excellent recovery opportunities for this group of metals. That is why eleven papers deal with the recovery of base metals [12][13][14][15][16][17][18][19][20][21][22] and one of precious metals [23].…”