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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur
KFM 17: Focus Session: Battery Materials – Experimental Characterisation and Safety Testing (joint session KFM/MM)
KFM 17.10: Vortrag
Mittwoch, 20. März 2024, 18:25–18:45, EMH 225
Exploring Polaron Stability and Defect Structures in Li4Ti5O12 (LTO): A Combined Theoretical and Experimental Approach — •Yu-Te Chan1, Matthias Kick2, Cristina Grosu2, Christoph Scheurer1, and Harald Oberhofer3 — 1Fritz-Haber-Institut der MPG, Berlin — 2Massachusetts Institute of Technology, Cambridge, USA — 3University of Bayreuth
Spinel Li4Ti5O12 (LTO) is a promising anode material for next-generation all-solid-state Li-ion batteries (ASSB) due to its "zero strain" charge/discharge behavior. Pristine, white LTO possesses poor ionic and electronic conductivity. Through tailoring the sintering protocol, one can produce oxygen vacancies accompanied by polaron formation, resulting in a performant, blue LTO material.
By performing Hubbard corrected density-functional theory (DFT+U) calculations we are able to show that polaron formation and a possible polaron hopping mechanism play a significant role in enhancing electronic conductivity and in boosting Li+ diffusion, in line with the experimentally observed improved conductivities.[1] We pair these findings with positron lifetime spectroscopy (PALS) to study the charge carriers’ (polaron and Li+) behavior and the defect structures produced in the sintering. We developed a machine-learned potential to study the dynamics of the polaron and the structural defects measured from PALS, reaching a rather complete picture of the bulk vs. surface defect chemistry in LTO particles.
[1] M. Kick et al., J. Phys. Chem. Lett. 11, 2535 (2020); ACS Appl. Energy Mater. 4, 8583 (2021).
Keywords: lithium titanate; polaron; battery