Effective Thermal Conductivity of Lithium‐Ion Battery Electrodes in Dependence on the Degree of Calendering

Abstract

The thermal conductivity represents a key parameter for the consideration of temperature control and thermal inhomogeneities in batteries. A high‐effective thermal conductivity will entail lower temperature gradients and thus a more homogeneous temperature distribution, which is considered beneficial for a longer lifetime of battery cells. Herein, the impact of the microstructure within the porous electrode coating obtained by different compression rates and its thermal contact to the current collector is investigated as both factors significantly determine the overall conduction through the electrode. The effective thermal conductivity of two graphite anodes and two lithium nickel manganese cobalt oxide cathodes is evaluated at different compression rates. It is found that the thermal conductivity does not have a monotone dependence on the porosity with changing compression rates. The results show a strong correlation with the adhesion strength, thus a significant impact of the thermal contact resistance between the coating and current collector is assumed.

Using resistor network models to predict the transport properties of solid-state battery composites

“…This thermal conductivity lies within the typical range for sulfidic solid-state electrolytes. 21,30 With a value of 0.71 ± 0.04 W m -1 K -1 , NCM83 shows the highest thermal conductivity of the investigated series in agreement with the thermal conductivities of calendared NCM cathodes reported by Gandert et al 44 An increase in effective thermal conductivity with increasing NCM83 volume fraction is observed.…”

Using resistor network models to predict the transport properties of solid-state battery composites

“…This thermal conductivity lies within the typical range for sulfidic solidstate electrolytes. 21,30 With a value of 0.71 ± 0.04 W m -1 K -1 , NCM83 shows the highest thermal conductivity of the investigated series in agreement with the thermal conductivities of calendared NCM cathodes reported by Gandert et al 44 An increase in effective thermal conductivity with increasing NCM83 volume fraction is observed.…”

High Areal Capacity Cation and Anionic Redox Solid-State Batteries Enabled by Transition Metal Sulfide Conversion

“…The lower thermal diffusivity exhibited in the cathode composite is supported by the lower thermal diffusivity of the Li 6 PS 5 Cl, relative to FeS:Li 2 S. 41 Based on those thermal diffusivities, thermal conductivities (eq 3) of the active material and cathode composite were calculated based on the specific heat capacities estimated using the Dulong−Petit limit (Figure 6b, see the Supporting Information). The thermal conductivity of the active material (FeS:Li 2 S) is within the range of thermal conductivities reported for calendared carbon-coated NCM622 and NCM811 sheets (∼0.5−1 W m −1 K −1 at 20 °C) 42 and NCM532 electrodes (∼0.5 W m −1 K −1 ). 43 It also is expected that the thermal conductivity of an NCM composite should also decrease with the introduction of Li 6 PS 5 Cl, which is reported to exhibit lower thermal conductivities (∼0.3−0.5 W m −1 K −1 at 20 °C).…”