Interrelationship Between the Open Circuit Potential Curves in a Class of Ni-Rich Cathode Materials. Issue 4 (17th February 2020)

• Record Type: Journal Article
• Authors: Kimura, Kevin W.; Wilhelm, Rebecca; Besli, Münir M.; Kim, Soo; Usubelli, Camille; Ziegler, Jörg C.; Klein, Reinhardt; Christensen, Jake; Gorlin, Yelena
• Is Part Of: Journal of the Electrochemical Society. Volume 167:Issue 4(2020)
• Publication Date: 2020-02-17
• Subjects: Electrochemistry -- Periodicals; 541.3705
• DOI: 10.1149/1945-7111/ab739c
• Languages: English
• ISSNs: 0013-4651

Abstract

Abstract : Ni-rich cathodes, such as nickel cobalt aluminum oxides (NCAs, Lix Ni0.80+0.15 ε Co0.15(1− ε ) Al0.05 O2, 0 ≤ ε ≤ 1), are a class of cathode materials for lithium-ion batteries (LIBs), which are among the leading candidates for battery electric vehicle (BEV) applications. In this study we focus on an important, fundamental electrochemical property, the open-circuit potential function (OCP, U vs x), and investigate its relationship with the Ni stoichiometry. First, we demonstrate that published differential capacity curves (dQ/dU vs U) for Ni-rich NCA materials can be derived as a stoichiometric linear combination of differential capacities of the two end members, Lix Ni0.8 Co0.15 Al0.05 O2 and Lix Ni0.95 Al0.05 O2 . Subsequently, the OCP curves are obtained by taking the inverse of the integrated dQ/dU vs U curves, which match literature OCP curves. Then, we apply the same method to determine the composition of an unknown cathode extracted from a commercially available LIB. Lastly, we show that the identified relationship also holds true for the Lix Ni0.60+0.20 ε Co0.20(1− ε ) Mn0.20 O2 family by demonstrating that the OCP curve of Lix Ni0.70 Co0.10 Mn0.20 O2 can be predicted from a fractional combination of Lix Ni0.60 Co0.20 Mn0.20 O2 and Lix Ni0.80 Mn0.20 O2 . We anticipate that this methodology can be adapted to predict OCP curves for additional cathode families and used to validate the chemical composition of newly synthesized materials.