This title appears in the Scientific Report :
2023
Microstructural properties of tape-cast LATP ceramic sheets for application in solid state batteries
Microstructural properties of tape-cast LATP ceramic sheets for application in solid state batteries
Solid-state batteries (SSB) are promising candidates for the next generation of energy storage devices, since this technology promises vastly improved safety and storage capacity compared to conventional Li-ion batteries [1]. In order to enable this technology further improvements of the solid elect...
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Personal Name(s): | Gross, Jürgen (Corresponding author) |
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Dashjav, Enkhtsetseg / Tietz, Frank / Malzbender, Jürgen / Ziegner, Mirko / Grüner, Daniel / Peter, Nicolas / Schwaiger, Ruth | |
Contributing Institute: |
Werkstoffsynthese und Herstellungsverfahren; IEK-1 Werkstoffstruktur und -eigenschaften; IEK-2 |
Imprint: |
2023
|
Conference: | Helmholtz Energy Conference 2023, Koblenz (Germany), 2023-06-12 - 2023-06-13 |
Document Type: |
Conference Presentation |
Research Program: |
ProFeLi - Produktionstechnik für Festkörperbatterien mit Lithium-Metall-Anode Fundamentals and Materials |
Publikationsportal JuSER |
Solid-state batteries (SSB) are promising candidates for the next generation of energy storage devices, since this technology promises vastly improved safety and storage capacity compared to conventional Li-ion batteries [1]. In order to enable this technology further improvements of the solid electrolyte (SE) in regards to manufacturing, ionic conductivity, microstructural and mechanical properties have to be made [2-4]. The solid electrolyte Li1+xAlxTi2-x(PO4)3 (LATP) is a promising material for the application as SE, in particular due to its high ionic conductivity and good compatibility towards certain active materials such as LiFePO4 [5-7]. Furthermore, in contrast to hygroscopic SEs, such as Li7La3Zr2O12, LATP exhibits a high stability against H2O and CO2 [8, 9], thus enabling production and handling in ambient air, leading to reduced production costs. Advanced components require industrial relevant production processes, of which in particular tape casting is of considerable interest. Processing-relevant sintering behavior needs to be optimized using sintering additives. Thus, 14 variations of tape-cast LATP with different chemical compositions and varying amounts of LiF and SiO2 additions have been investigated with respect to their microstructure and especially their phase compositions. A comparison of their chemical and phase composition revealed an increase in the amount of the orthorhombic LATP phase with increasing lithium content, indicating that orthorhombic LATP is a lithium-rich modification. The orthorhombic LATP phase exhibit a much lower ionic conductivity compared to its rhombohedral modification, thus has a negative effect on the battery performance. Based on high-temperature X-ray diffraction, a rhombohedral – orthorhombic LATP phase equilibrium was identified, shifting towards the rhombohedral phase at temperatures > 800 °C. Above 1000 °C no orthorhombic LATP could be detected, therefore an additional heat treatment dissolves this phase, potentially improving the materials property, however it is known at higher sintering temperatures the severity of microcracks within LATP increases. SEM micrograph analysis revealed that both LiF and SiO2 are beneficial for the densification of the material. Although increased SiO2 addition led to decreased densifications, the SiO2 addition successfully inhibited the LATP grain growth, leading to smaller average grain sizes, thus reducing the severity of micro-cracks. Based on Ball-on-3 balls bending results an increase of the material strength with decreasing porosity can be observed, however below 18% porosity, a sharp drop of the material strength from ~150 MPa to ~50 MPa is detected. Fracture surface analysis revealed a shift of the fracture origin, where at higher porosities (>18%) pores and at lower porosities (<18%) micro-cracks are causing material failure under applied stress. This might be expected since dense tape cast LATP requires higher sintering temperatures, although the use of SiO2 as a sintering additive appears to be a promising approach to reduce the micro-crack severity. However based on these result the application of dense LATP in solid state batteries is not straight forward. Porous tape cast LATP on the other hand, might be used as a skeleton-structure for polymer infiltrated cathode composites, since it can be obtained at lower sintering temperatures. However, a high amount of o-LATP might be expected, which requires clarification of its effects also on the performance of cathode composites, which will be the aim of future studies.[1] F. Zheng, M. Kotobuki, S. Song, M. O. Lai, and L. Lu, "Review on solid electrolytes for all-solid-state lithium-ion batteries," Journal of Power Sources, vol. 389, pp. 198-213, 2018.[2] R. Chen, W. Qu, X. Guo, L. Li, and F. Wu, "The pursuit of solid-state electrolytes for lithium batteries: from comprehensive insight to emerging horizons," Materials Horizons, vol. 3, no. 6, pp. 487-516, 2016.[3] A. Manthiram, X. Yu, and S. Wang, "Lithium battery chemistries enabled by solid-state electrolytes," Nature Reviews Materials, vol. 2, no. 4, pp. 1-16, 2017.[4] T. Shi, Y.-Q. Zhang, Q. Tu, Y. Wang, M. Scott, and G. Ceder, "Characterization of mechanical degradation in an all-solid-state battery cathode," Journal of Materials Chemistry A, vol. 8, no. 34, pp. 17399-17404, 2020.[5] E. Dashjav et al., "Microstructure, ionic conductivity and mechanical properties of tape-cast Li1. 5Al0. 5Ti1. 5P3O12 electrolyte sheets," Journal of the European Ceramic Society, 2020.[6] E. Dashjav et al., "The influence of water on the electrical conductivity of aluminum-substituted lithium titanium phosphates," Solid State Ionics, vol. 321, pp. 83-90, 2018.[7] M. Gellert, E. Dashjav, D. Grüner, Q. Ma, and F. Tietz, "Compatibility study of oxide and olivine cathode materials with lithium aluminum titanium phosphate," Ionics, vol. 24, no. 4, pp. 1001-1006, 2018.[8] G. y. Adachi, N. Imanaka, and H. Aono, "Fast Li⊕ conducting ceramic electrolytes," Advanced Materials, vol. 8, no. 2, pp. 127-135, 1996.[9] E. Bucharsky, K. Schell, A. Hintennach, and M. Hoffmann, "Preparation and characterization of sol–gel derived high lithium ion conductive NZP-type ceramics Li1+ x AlxTi2− x (PO4) 3," Solid State Ionics, vol. 274, pp. 77-82, 2015. |