Modeling Current Density Non-Uniformity to Detect Premature Failure in 3D Lithium-Ion Batteries

Abstract

Conventional Lithium-ion (Li-ion) intercalation batteries that are composed of planar cathode, separator, and anode layers bear an intrinsic trade-off between energy density and power density. While thick electrodes allow for more active material loading and higher energy densities, thick electrodes lengthen ion transport pathways and limit power and fast charging performance. Conversely, thin electrodes have fast ion transport at the cost of reduced material loading which leads to lower energy densities. Due to the high weight and volume ratio of inactive components, stacking layers of thin planar batteries is inefficient for high capacity cells.1 Three-dimensional (3D) batteries decouple the power-energy trade-off in planar batteries by modifying electrode architecture on a micron to millimeter scale.2 3D batteries redistribute electrode material beyond planar geometry to controlled 3D spatial arrangements in pursuance of shorter ion-transport pathways and enhanced fast charging behavior in a battery cell. This enables high power performance without sacrificing the mass of active material in the cell, and ideally maintains high energy and power performance at high discharge and charge rates. However, a known issue in 3D batteries is the inhomogeneous transport distances between electrodes leading to nonuniform current density and local depletion of the electrode or electrolyte material.3,4 These nonuniformities can terminate a discharge or charge cycle prematurely. Although many 3D batteries have been proposed to date, few comparative modeling studies have been conducted for these architectures to understand their relative performance gains.In this work, we adapt a two-dimensional current density uniformity index (UI) measure from previous work5 and investigate its usage as a potential 3D metric for quantifying premature failure in 3D batteries. A series of 3D batteries are simulated using the software AMPERES that models a 3D electrochemical systems at the continuum level using volume-averaging techniques.6 Two material models – LiFePO4 (LFP) | Li4Ti5O12 (LTO) and LiNi0.5Mn0.3Co0.2O2 (NMC532) | Graphite – are investigated for each 3D battery architecture. We also visualize 3D Li-ion concentration profiles and Li-ion transport pathways to qualitatively analyze the transport behavior in each 3D battery. Our results show that 3D battery performance is material dependent, and 3D batteries with premature depletion demonstrate high UI metrics early in a discharge cycle. References C. L. Cobb and S. E. Solberg, J. Electrochem. Soc., 164, A1339–A1341 (2017).C. L. Cobb and M. Blanco, Journal of Power Sources, 249, 357–366 (2014).R. Hart, H. White, B. Dunn, and D. Rolison, Electrochemistry Communications, 5, 120–123 (2003).A. A. Talin, D. Ruzmetov, A. Kolmakov, K. McKelvey, N. Ware, F. El Gabaly, B. Dunn, and H. S. White, ACS Appl. Mater. Interfaces, 8, 32385–32391 (2016).D. Grazioli, V. Zadin, D. Brandell, and A. Simone, Electrochimica Acta, 296, 1142–1162 (2019).S. Allu, S. Kalnaus, S. Simunovic, J. Nanda, J.A. Turner, and S. Pannala, Journal of Power Sources, 325, 42–50 (2016). Acknowledgements This work was funded in part by a Defense Advanced Research Projects Agency (DARPA) Young Faculty Award under grant number D19AP00038. The views, opinions, and/or findings expressed are those of the authors and should not be interpreted as representing the official views or policies of the Department of Defense or the U.S. Government.