Understanding the Effect of Cathode Composition on the Interface and Crosstalk in NMC/Si Full Cells

Crosstalk between the cathode and the anode in lithium-ion batteries has a great impact on performance, safety, and cycle lifetime. However, no report exists for a systematic investigation on crosstalk behavior in silicon (Si)-based cells as a function of transition metal composition in cathodes. We studied the effect of crosstalk on degradation of Si-rich anodes in full cells with different cathodes having the same crystal structure but different transition metal compositions, such as LiNi1/3Mn1/3Co1/3O2 (NM111), LiNi0.5Mn0.3Co0.2O2 (NMC532), and LiNi0.8Mn0.1Co0.1O2 (NMC811). We found that the transition metal composition in cathodes, especially Mn ion concentration, significantly affects electrolyte decomposition reactions, even from very early cycles. This change causes differences in the solid electrolyte interphase (SEI) chemistry of each aged Si sample. As a result, each of the aged Si samples has a different electrochemistry, in terms of initial Coulombic efficiency and the mechanism of capacity fade.

Automated summary

The crosstalk between cathodes and anodes in lithium-ion batteries has a significant impact on performance and cycle lifetime. This study investigates the effect of crosstalk on the degradation of Si-rich anodes in cells with different cathodes of the same crystal structure but varying transition metal compositions. The results show that the transition metal composition, particularly the concentration of Mn ions, in the cathodes significantly affects the electrolyte decomposition reactions, leading to differences in the solid electrolyte interphase (SEI) chemistry and electrochemistry of the aged Si samples.