Performance Limitations in Ni-Rich, High-Energy Lithium-Ion-Battery Cathodes

Abstract

Lithium-ion batteries with Ni-rich stoichiometries such as LiNi0.8Mn0.1Co0.1O2 (NMC811) have gainedimportance due to the reduction of critical resources such as cobalt. While these cathode materialswith high nickel content offer high specific capacity [1], their rate capability is significantly reducedcompared to other chemistries. In the present work, the combination of large-volume FIB/SEMtomography, structurally-resolved simulation, and electrochemical half-cell analysis is used tocharacterize the cathode microstructure of a commercial high-energy cell. Detailed structural datawere obtained by FIB/SEM tomography and used to optimize the simulation approach to accuratelydescribe the discharge capacity and electrode impedance simultaneously. Poor electrical conductivityis identified as the main cause of power loss. An optimized, artificial structure with up to 10% higher1C discharge capacity compared to the original structure is developed by increasing and homogenizingthe conductive binder network. This tool enables further understanding of structural aging anddegradation effects by correlating structural changes with performance losses.AcknowledgementsThis work was funded by the German Ministry for Education and Research under the reference number03XP0317D.