Modeling of pulse and relaxation of high-rate Li/CFx-SVO batteries in implantable medical devices.

We present a Hybrid Multiphase Porous Electrode Theory (Hybrid-MPET) model that accurately predicts the performance of Medtronic's implantable medical device battery lithium/carbon monofluoride (C F x) - silver vanadium oxide (SVO) under both low-rate background monitoring and high-rate pulsing currents. The distinct properties of multiple active materials are reflected by parameterizing their thermodynamics, kinetics, and mass transport properties separately. Diffusion limitations of Li + in SVO are used to explain cell voltage transient behavior during pulse and post-pulse relaxation. We also introduce change in cathode electronic conductivity, Li metal anode surface morphology, and film resistance buildup to capture evolution of cell internal resistance throughout multi-year electrical tests. We share our insights on how the Li + redistribution process between active materials can restore pulse capability of the hybrid electrode, allow C F x to indirectly contribute to capacity release during pulsing, and affect the operation protocols and design principles of batteries with other hybrid electrodes. We also discuss additional complexities in porous electrode model parameterization and electrochemical characterization techniques due to parallel reactions and solid diffusion pathways across active materials. We hope our models can complement future experimental research and accelerate development of multi-active material electrodes with targeted performance. • Hybrid-MPET model of Medtronic's high-rate Li/CF x -SVO battery is presented. • Separate material properties, diffusion limitation, and aging are accounted for. • Model prediction accuracy is validated on large battery dataset. • Cell pulse capability restoration is explained by Li＋ redistribution across materials. • Li＋ redistribution impact on general cell operation and design principles are discussed. [ABSTRACT FROM AUTHOR]