Gi-Heon_KimGi-Heon Kim, Ph.D., Distinguished Researcher and Team Lead, Energy Storage Modeling, Hydrogen and Transportation Systems Center, National Renewable Energy Laboratory (NREL) is a presenter at the 6th Annual Battery Safety conference in Baltimore.

Below, he discusses NREL’s multiscale multidimensional modeling approach, variables affecting LIB safety responses and more.

Lithium-Ion Battery Safety: An Intrinsically Multiphysics Problem

1) Can you describe how you came to work on Li-ion battery safety research and engineering, and what resources you have at NREL for carrying out this work?

The concern over the safety of lithium-ion batteries (LIBs) is one of the major obstacles for accelerating the market adoption of electric drive vehicles. With the support of the U.S. Department of Energy (DOE), the National Renewable Energy Laboratory (NREL) has cultivated world-leading expertise in battery multiphysics modeling to develop innovations necessary for the industry to meet the nation’s EV Everywhere Grand Challenge and related targets for vehicle electrification.

LIB safety is an intrinsically multiphysics problem. In an incident, thermal-, electrical-, electrochemical-, chemical-, and mechanical responses of a faulted battery are tightly coupled with design and environmental conditions. NREL’s multiphysics MSMD model framework provides a modular architecture, facilitating flexible integration of multiphysics model components. Interdisciplinary constitutive models are integrated to properly simulate the response of a battery developing a safety fault.

The model’s application to real-world problems revealed complex mechanisms affecting LIB safety behaviors and helped the industry improve their design and the management strategies. The model code has been licensed to multiple partners, and several patents were issued based on the knowledge enhanced by the model.

2) What hurdles -- technical or otherwise -- must still be overcome when using multiscale, multiphysics modeling for simulation and ultimately prediction of battery behaviors?

LIB safety responses are significantly affected by many sensitive factors in material, design, and operational/environmental conditions. Therefore, to identify the causes and to quantify the impacts, the model simulations must be carefully designed.

NREL seeks to address this issue by providing a toolset that evaluates the impacts of various physical aspects in a fault event:

  • Location of internal short circuit within the cell
  • Rate of shorting resistance change with time
  • Variation in cell thermal/electrical conductivity during the short
  • Location of faulted cell within module/pack
  • Influence of system cooling status
  • Initial system temperature
  • Electrical power flow between faulted cell and other cells
  • Temperature of the pack surroundings

This requires multiple constitutive models to be properly identified when integrated into the MSMD framework.

3) Why have you chosen to speak at this Battery Safety conference, and what do you hope your presentation on "Integrated Multiscale Multiphysics Modeling of Safety Response Behaviors of Large Lithium-Ion Batteries" will convey to your audience?

The Battery Safety conference is well attended and attracts leading international experts from academia and industry. As DOE’s leading national lab in LIB safety modeling research, we would like to engage the audience with the latest progress in NREL’s modeling capability and discuss the findings from our recent studies.

Speaker Information:

Dr. Gi-Heon Kim is Distinguished Researcher at the U.S. Department of Energy’s National Renewable Energy Laboratory (NREL). He leads the multiphysics energy storage modeling team at NREL. Dr. Kim is the lead developer of NREL’s pioneering multiscale multiphysics battery model, the MSMD and the GH-MSMD – a new innovative quasi-explicit nonlinear multiscale multiphysics framework, resolving the nonlinear interplay of Li-ion battery physics in varied length scales. In recent years, Gi-Heon serves as a technical advisor/monitor and PI in multiple DOE sponsored battery model development projects. He is also internationally recognized for his expertise in Li-ion battery safety research and engineering and has multiple publications and patents.