Power and thermal characterization of a lithium-ion battery pack for hybrid-electric vehicles

Kandler Smith, Chao Yang Wang

Research output: Contribution to journalArticlepeer-review

621 Scopus citations


A 1D electrochemical, lumped thermal model is used to explore pulse power limitations and thermal behavior of a 6 Ah, 72 cell, 276 V nominal Li-ion hybrid-electric vehicle (HEV) battery pack. Depleted/saturated active material Li surface concentrations in the negative/positive electrodes consistently cause end of high-rate (∼25 C) pulse discharge at the 2.7 V cell-1 minimum limit, indicating solid-state diffusion is the limiting mechanism. The 3.9 V cell-1 maximum limit, meant to protect the negative electrode from lithium deposition side reaction during charge, is overly conservative for high-rate (∼15 C) pulse charges initiated from states-of-charge (SOCs) less than 100%. Two-second maximum pulse charge rate from the 50% SOC initial condition can be increased by as much as 50% without risk of lithium deposition. Controlled to minimum/maximum voltage limits, the pack meets partnership for next generation vehicles (PNGV) power assist mode pulse power goals (at operating temperatures >16 °C), but falls short of the available energy goal. In a vehicle simulation, the pack generates heat at a 320 W rate on a US06 driving cycle at 25 °C, with more heat generated at lower temperatures. Less aggressive FUDS and HWFET cycles generate 6-12 times less heat. Contact resistance ohmic heating dominates all other mechanisms, followed by electrolyte phase ohmic heating. Reaction and electronic phase ohmic heats are negligible. A convective heat transfer coefficient of h = 10.1 W m-2 K-1 maintains cell temperature at or below the 52 °C PNGV operating limit under aggressive US06 driving.

Original languageEnglish (US)
Pages (from-to)662-673
Number of pages12
JournalJournal of Power Sources
Issue number1
StatePublished - Sep 29 2006

All Science Journal Classification (ASJC) codes

  • Renewable Energy, Sustainability and the Environment
  • Energy Engineering and Power Technology
  • Physical and Theoretical Chemistry
  • Electrical and Electronic Engineering


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