How Fast Charging Affects Manganese Spinel Structure
Authors: Buchberger Dominika , Glaszczka Alicja , Winkowska-Struzik Magdalena , Manippady Sai Rashmi , Struzik Michal , Czerwinski Andrzej 
Published: December 2024

Lithium-ion batteries have transformed the market of portable electronics and electric vehicle due to their high energy density and efficiency. Positive electrode materials play a critical role in determining the performance and stability of Li-ion batteries. LiMn2O4 (LMO) and LiNi0.5Mn1.5O4 (LMNO) are important positive electrode materials known for their valuable electrochemical properties.1 LMO, a manganese-based spinel, exhibits low cost and high working potential, making it attractive material for consumer electronics.3 On the other hand, LMNO, which incorporates nickel into the manganese spinel structure, offers enhanced specific capacity and cycling stability, making it a potential candidate for high-energy applications such as electric vehicles.4,5

This study investigates the impact of fast charging on the structure of spinel-based positive electrode materials, focusing on LMO and LMNO representatives. Fast charging is achieved using the constant current constant voltage (CCCV) method, a common technique in Li-ion battery charging protocol characterized by an initial constant current phase followed by a constant voltage phase. We investigated samples charged at 2C, 5C and 10C-rate current as well as different voltage cut-off conditions. Ex situ Raman mapping, X-ray diffraction (XRD) and scanning electron microscopy (SEM) are employed to assess structural changes and possible impurity formation during the fast charging processes. Raman mapping is very sensitive on local structural changes and gives detailed insights into electrode composition with good statistics. By probing vibrational modes associated with spinel structures, the technique provides spatially resolved data on phase distribution and impurity formation. XRD complements this analysis by providing bulk structural information, including lattice parameters and crystallographic phase changes induced by fast charging. The combined application of these techniques allows a comprehensive understanding of the electrode's response to harsh charging conditions. This study underlines the importance of investigating structural stability and highlights the utility of readily available and very capable techniques, including Raman mapping and XRD, in explaining the mechanisms behind performance decline and capacity loss in Li-ion battery electrodes subjected to fast charging. An in-depth understanding of structural changes under fast charging conditions, especially in view of the growing fast charging infrastructure, is crucial for the advancement of battery technology.
This work was funded by the National Center for Science in Poland through the Sonata BIS 11 programme (No. UMO-2021/42/E/ST5/00390).

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