Heat capacities of selected battery materials and components

Abstract

The specific heat capacities of solid battery materials like active electrode materials and separators were measured from approx. 300–550 K in this study. First, the method was validated by measuring the heat capacities of active anode materials silicon and tin disulfide, which could then be compared to data from literature. The second set of measurements were done on two separator materials (Celgard 2500 and Whatman GF/C), and the results were compared to the heat capacity measurements of pure polypropylene and borosilicate glass from literature. The C_p of Celgard 2500 was between of 1.79 and 2.16 J.g⁻¹K⁻¹ and the Cp of Whatman GF/C was between 0.83 and 0.96 J.g⁻¹K⁻¹. In addition, heat capacity values of both types of LiNi_0.5Mn_1.5O₄ (LNMO), disordered LNMO (DLNMO) and ordered LNMO (OLNMO), are reported for the first time, ranging between 0.72–0.90 J.g⁻¹K⁻¹ and 0.73–0.86 J.g⁻¹K⁻¹ for DLNMO and OLNMO, respectively. Compared to each other, both DLNMO and OLNMO have similar heat capacities at lower temperatures. However, with increasing temperature, DLNMO starts to have higher heat capacities. Both heat capacities were compared to a heat capacity calculation according to Neumann–Kopp based on the heat capacities of the binary oxides. When compared to the “Parent” material LiMn₂O₄ (LMO), both DLNMO and OLNMO had lower heat capacities. The data are highly relevant for battery thermal management and for thermal modeling and simulation of lithium-ion batteries.