| Summary: | The electrolyte is one of the three essential constituents of a Lithium-Ion battery (LiB) in addition to the anode and cathode. During increasingly high power and high current charging and discharging, the requirement for the electrolyte becomes more strict. Solid State Electrolyte (SSE) sees its niche for high power applications due to its ability to suppress concentration polarization and otherwise stable properties also related to safety. During high power and high current cycling, heat management becomes more important and thermal conductivity measurements are needed. In this work, thermal conductivity was measured for three types of solid state electrolytes: Li<inline-formula> <math display="inline"> <semantics> <msub> <mrow></mrow> <mn>7</mn> </msub> </semantics> </math> </inline-formula>La<inline-formula> <math display="inline"> <semantics> <msub> <mrow></mrow> <mn>3</mn> </msub> </semantics> </math> </inline-formula>Zr<inline-formula> <math display="inline"> <semantics> <msub> <mrow></mrow> <mn>2</mn> </msub> </semantics> </math> </inline-formula>O<inline-formula> <math display="inline"> <semantics> <msub> <mrow></mrow> <mn>12</mn> </msub> </semantics> </math> </inline-formula> (LLZO), Li<inline-formula> <math display="inline"> <semantics> <msub> <mrow></mrow> <mrow> <mn>1.5</mn> </mrow> </msub> </semantics> </math> </inline-formula>Al<inline-formula> <math display="inline"> <semantics> <msub> <mrow></mrow> <mrow> <mn>0.5</mn> </mrow> </msub> </semantics> </math> </inline-formula>Ge<inline-formula> <math display="inline"> <semantics> <msub> <mrow></mrow> <mrow> <mn>1.5</mn> </mrow> </msub> </semantics> </math> </inline-formula>(PO<inline-formula> <math display="inline"> <semantics> <msub> <mrow></mrow> <mn>4</mn> </msub> </semantics> </math> </inline-formula>)<inline-formula> <math display="inline"> <semantics> <msub> <mrow></mrow> <mn>3</mn> </msub> </semantics> </math> </inline-formula> (LAGP), and Li<inline-formula> <math display="inline"> <semantics> <msub> <mrow></mrow> <mrow> <mn>1.3</mn> </mrow> </msub> </semantics> </math> </inline-formula>Al<inline-formula> <math display="inline"> <semantics> <msub> <mrow></mrow> <mrow> <mn>0.3</mn> </mrow> </msub> </semantics> </math> </inline-formula>Ti<inline-formula> <math display="inline"> <semantics> <msub> <mrow></mrow> <mrow> <mn>1.7</mn> </mrow> </msub> </semantics> </math> </inline-formula>(PO<inline-formula> <math display="inline"> <semantics> <msub> <mrow></mrow> <mn>4</mn> </msub> </semantics> </math> </inline-formula>)<inline-formula> <math display="inline"> <semantics> <msub> <mrow></mrow> <mn>3</mn> </msub> </semantics> </math> </inline-formula> (LATP) at different compaction pressures. LAGP and LATP were measured after sintering, and LLZO was measured before and after sintering the sample material. Thermal conductivity for the sintered electrolytes was measured to 0.470 ± 0.009 WK<inline-formula> <math display="inline"> <semantics> <msup> <mrow></mrow> <mrow> <mo>−</mo> <mn>1</mn> </mrow> </msup> </semantics> </math> </inline-formula>m<inline-formula> <math display="inline"> <semantics> <msup> <mrow></mrow> <mrow> <mo>−</mo> <mn>1</mn> </mrow> </msup> </semantics> </math> </inline-formula>, 0.5 ± 0.2 WK<inline-formula> <math display="inline"> <semantics> <msup> <mrow></mrow> <mrow> <mo>−</mo> <mn>1</mn> </mrow> </msup> </semantics> </math> </inline-formula>m<inline-formula> <math display="inline"> <semantics> <msup> <mrow></mrow> <mrow> <mo>−</mo> <mn>1</mn> </mrow> </msup> </semantics> </math> </inline-formula> and 0.49 ± 0.02 WK<inline-formula> <math display="inline"> <semantics> <msup> <mrow></mrow> <mrow> <mo>−</mo> <mn>1</mn> </mrow> </msup> </semantics> </math> </inline-formula>m<inline-formula> <math display="inline"> <semantics> <msup> <mrow></mrow> <mrow> <mo>−</mo> <mn>1</mn> </mrow> </msup> </semantics> </math> </inline-formula> for LLZO, LAGP, and LATP respectively. Before sintering, LLZO showed a thermal conductivity of 0.22 ± 0.02 WK<inline-formula> <math display="inline"> <semantics> <msup> <mrow></mrow> <mrow> <mo>−</mo> <mn>1</mn> </mrow> </msup> </semantics> </math> </inline-formula>m<inline-formula> <math display="inline"> <semantics> <msup> <mrow></mrow> <mrow> <mo>−</mo> <mn>1</mn> </mrow> </msup> </semantics> </math> </inline-formula>. An analytical temperature distribution model for a battery stack of 24 cells shows temperature differences between battery center and edge of 1−2 K for standard liquid electrolytes and 7−9 K for solid state electrolytes, both at the same C-rate of four.
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