THERMAL SCIENCE

International Scientific Journal

THERMAL ANALYSIS OF PRISMATIC LI-ION BATTERY PACKS UNDER TYPICAL OPERATING CONDITIONS: EFFECT OF AIR GAP ON REPRESENTATIVE TEMPERATURES

ABSTRACT
Thermal analysis of a battery pack with a prismatic lithium-ion battery under typical operating conditions was conducted to study the influence of the environment on its temperature. Two scenarios were considered: with an air gap between the battery and the inner surface of the battery pack case, and without air gaps. Numerical analysis of temperature fields was performed at ambient temperatures ranging from 15°C to 30°C and nominal discharge/charge currents, with heat exchange coefficients from external surfaces of α = 5 and 10 W/(m²•K). Theoretical analysis of representative temperatures in the battery pack with a Li-ion battery of the LFP type was based on solving the heat conduction equation in a one-dimensional formulation. The finite difference method with an implicit four-point difference approximation scheme was used. Conditions of continuity of heat flows and temperatures were set on the internal boundaries of the model elements, while convective heat exchange with the environment was accounted for on the external boundaries of the case surface. Numerical studies showed that the maximum temperature of a typical lithium-ion battery in a pack with technological air gaps is 2-3°C higher than that of a battery in a pack without gaps, even for nominal operational loads. The air gap between the battery and the pack case reduces the intensity of heat removal. The main result of the theoretical studies is the justification for the need to account for air gaps in lithium-ion battery packs, as well as the determination of the actual representative temperatures of Li-ion batteries in battery packs for thermal management systems of chemical current sources.
KEYWORDS
PAPER SUBMITTED: 2025-04-19
PAPER REVISED: 2025-12-29
PAPER ACCEPTED: 2026-01-15
PUBLISHED ONLINE: 2026-06-20
DOI REFERENCE: https://doi.org/10.2298/TSCI250419067K
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