Thermal conductivity and internal temperature profiles of Li-ion secondary batteries Frank Richter a , Signe Kjelstrup a , Preben J. S. Vie b , Odne S. Burheim c,∗ a Department of Chemistry, Norwegian University of Science and Technology, NO-7491 Trondheim, Norway b Institute for Energy Technology, Instituttveien 18, NO-2007 Kjeller, Norway c Department of Energy and Process Engineering, Norwegian University of Science and Technology, NO-7491 Trondheim, Norway Abstract In this paper we report the thermal conductivity for several battery components. Materials were obtained from several electrode- and separator suppliers, and some were extracted from commercial batteries. We measured with and without electrolyte solvent and at different compaction pressures. The experimentally obtained values are used in a thermal model and corresponding internal temperature profiles are shown. The thermal conductivity of dry separator materials was found to range from 0.07 ± 0.01 to 0.18 ± 0.02 WK −1 m −1 . Dry electrode (active) materials ranged from 0.13 ± 0.02 to 0.61 ± 0.02 WK −1 m −1 . Adding the electrolyte solvent increased the thermal conductivity of electrode (active) materials by at least a factor of 2. Keywords: thermal conductivity measurements, temperature profile, thermal modelling, Li-ion battery 1. Introduction Li-ion batteries have seen a major introduction to small scale hybrid and fully electric vehicles. As larger battery cells have become cheaper, Li-ion based batteries are currently seeing an introduction to large scale electric and hybrid electric vehicles [1], e.g.electric buses, hybrid electric buses and hybrid electric ships [2]. As larger vehicles take batteries into use, larger battery packs are needed, and more intense cycles are applied. Therefore, thermal management becomes more important, both internally and externally. The growing use of Li-ion batteries is not only due to their zero emission characteristic during operation and their rather low carbon footprint [3]. It has also been shown, that a more cost efficient application can be realized [2] but the specific energy of the battery is still a limiting factor, when we compare to gasoline-driven vehicles [4]. Fast charging of LIBs would require a good understanding of heat production and heat transfer within the battery. Effects like capacity fade, power fade, and self discharge within Li-ion batteries are well reported in the literature, e.g. by Bandhauer et al. [5]. Especially the temperature influence on different ageing mechanisms is well reported [6–9]. ∗ Corresponding author: burheim@ntnu.no Email addresses: frank.richter@ntnu.no (Frank Richter), signe.kjelstrup@ntnu.no (Signe Kjelstrup), preben.vie@ife.no (Preben J. S. Vie), burheim@ntnu.no (Odne S. Burheim) Preprint submitted to Journal of Power Sources February 26, 2017