Investigating the intrinsic properties of cathode active material for Li-ion cells by combining single particle measurements with simulations

A detailed understanding of the intrinsic electrochemical properties of cathode active material is imperative for improving current and developing next-generation Li-ion batteries (LIBs). Conventional methods of electrochemical analysis of novel or optimized active materials involve the study of composite electrodes which contain a mixture of active material, binder, and conductive additive on a metallic current collector (CC) foil. The resulting electrochemical response is convoluted and is a function of various factors such as electrode thickness, porosity and composition, making it difficult to assess the intrinsic nature of the active material [1].

To accurately measure intrinsic material properties, the aforementioned matrix effect needs to be removed. This can be achieved by the development of localized electrochemical probes with which single particle measurements (SPMs) can be performed. Thereby, SPM facilitates the determination of the impact of particle size, shape etc. on electrochemical behavior of a given material. Here, we employ a pipette-based measurement technique called scanning micropipette contact method (SMCM) [2] to study the kinetic and transport properties of active materials.
Various electrochemical measurements, such as cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and rate capability tests, were successfully obtained using the SPM set-up. Similar measurements will be performed on an electrode scale to complement SPM.

Parameters derived from these experiments will be used as input for 3D electrochemical simulations on a particle level and subsequently on an electrode level, providing a more thorough insight into the underlying phenomena. Hence, SPM coupled with simulations can serve as a powerful tool to investigate the performance of different types of active materials.

References:

[1] C. Heubner, U. Langklotz, C. Lämmel, M. Schneider, and A. Michaelis, Electrochimica Acta, vol. 330, p. 135160, 2020.

[2] M. E. Snowden, M. Dayeh, N. A. Payne, S. Gervais, J. Mauzeroll, and S. B. Schougaard, Journal of Power Sources, vol. 325, pp. 682–689, 2016.