Modeling Current Density Non-Uniformities to Understand High-Rate Limitations in 3D Interdigitated Lithium-ion Batteries

Conventional planar Lithium-ion battery (LIB) cells are composed of a cathode and an anode with a polymer separator sheet sandwiched in between. Three-dimensional (3D) interdigitated batteries, where an anode and a cathode are intertwined, have been proposed as an alternative to planar LIBs to significantly improve energy, power, and fast charge performance. Various 3D battery designs have been demonstrated by researchers over the years, but a systematic study of how architecture and material impact 3D battery performance has been limited. In this paper, we conduct a comparative 3D computational modeling study on four 3D interdigitated battery designs previously shown in literature. We model each 3D battery using Li4Ti5O12 (LTO)|LiFePO4 (LFP) and Graphite|LiNi0.5Mn0.3Co0.2O2 (NMC), two widely studied LIB material systems, while conserving mass across all designs. Moreover, we propose a 3D current density metric to evaluate 3D LIBs and quantify the impact of current non-uniformities on high-rate LIB performance. Our results indicate that material selection and 3D architecture are equally critical for maximizing performance at high discharge rates. In addition, our analysis suggests quantifying the rate of change in current density early in a model discharge cycle can be a guiding metric to screen designs more quickly for premature failure.