A routine for the determination of the microstructure of stacking‐faulted nickel cobalt aluminium hydroxide precursors for lithium nickel cobalt aluminium oxide battery materials. Issue 1 (18th December 2019)

• Record Type: Journal Article
• Authors: Bette, Sebastian; Hinrichsen, Bernd; Pfister, Daniela; Dinnebier, Robert, E.
• Is Part Of: Journal of applied crystallography. Volume 53:Issue 1(2020)
• Page Start: 76
• Page End: 87
• Publication Date: 2019-12-18
• Subjects: stacking faults -- powder diffraction -- TOPAS -- battery materials -- nickel cobalt aluminium (NCA) precursors; Crystallography -- Periodicals; 548.05
• DOI: 10.1107/S1600576719016212
• Languages: English
• ISSNs: 0021-8898

Abstract

Abstract : Stacking faults and interstratification faults in a cobalt‐ and aluminium‐bearing nickel layered double hydroxide used as a precursor for Li(Ni1− x − y Co x Al y )O2 battery materials were quantified by a combination of a grid‐search approach and a recursive routine for generating and averaging supercells of stacking‐faulted layered substances implemented in the TOPAS software. Abstract : The microstructures of six stacking‐faulted industrially produced cobalt‐ and aluminium‐bearing nickel layered double hydroxide (LDH) samples that are used as precursors for Li(Ni1− x −y Co x Al y )O2 battery materials were investigated. Shifts from the brucite‐type (AγB)□(AγB)□ stacking pattern to the CdCl2 ‐type (AγB)□(CβA)□(BαC)□ and the CrOOH‐type (BγA)□(AβC)□(CαB)□ stacking order, as well as random intercalation of water molecules and carbonate ions, were found to be the main features of the microstructures. A recursive routine for generating and averaging supercells of stacking‐faulted layered substances implemented in the TOPAS software was used to calculate diffraction patterns of the LDH phases as a function of the degree of faulting and to refine them against the measured diffraction data. The microstructures of the precursor materials were described by a model containing three parameters: transition probabilities for generating CdCl2 ‐type and CrOOH‐type faults and a transition probability for the random intercalation of water/carbonate layers. Automated series of simulations and refinements were performed, in which the transition probabilities were modified incrementally and thus the microstructures optimized by a grid search. All samples were found to exhibit the same fraction of CdCl2 ‐type and CrOOH‐type stacking faults, which indicates that they have identical Ni, Co and Al contents. Different degrees of interstratification faulting were determined, which could be correlated to different heights of intercalation‐water‐related mass‐loss steps in the thermal analyses.