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Broadband impedance spectroscopy of Li 4 Ti 5 O 12 : from nearly constant loss effects to long‐range ion dynamics
Author(s) -
Gadermaier Bernhard,
Hogrefe Katharina,
Heitjans Paul,
Wilkening H. Martin R.
Publication year - 2021
Publication title -
zeitschrift für anorganische und allgemeine chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.354
H-Index - 66
eISSN - 1521-3749
pISSN - 0044-2313
DOI - 10.1002/zaac.202100143
Subject(s) - ion , dielectric spectroscopy , relaxation (psychology) , materials science , spectroscopy , anode , range (aeronautics) , lithium (medication) , atmospheric temperature range , analytical chemistry (journal) , plateau (mathematics) , chemical physics , condensed matter physics , chemistry , electrochemistry , thermodynamics , physics , electrode , medicine , psychology , social psychology , mathematical analysis , mathematics , organic chemistry , quantum mechanics , composite material , chromatography , endocrinology
Li 4 Ti 5 O 12 (LTO) is known as one of the most robust and long‐lasting anode materials in lithium‐ion batteries. As yet, the Li‐ion transport properties of LTO are, however, not completely understood. Here, we used broadband impedance spectroscopy spanning a wide temperature range to investigate the full electrical response of LTO over a wide frequency range. It turned out that the isotherms recorded entail information about two relaxation processes. While at high temperatures the isotherms show a frequency independent plateau that corresponds to poor long‐range ion transport (<10 −11 S cm −1 (298 K), 0.79 eV), they reveal a second region, seen at lower temperatures and higher frequencies, which we attribute to short‐range ion dynamics (10 −8 S cm −1 ) with a significantly reduced activation energy of ca. 0.51 eV. At even lower temperatures, the isotherms are fully governed by nearly constant loss behavior, which has frequently been explained by cage‐like dynamics. The present results agree with those earlier presented by 7 Li NMR spin‐lattice relaxation measurements being sensitive to dynamic processes taking place on quite different length scales. Our findings unveil complex Li + ion dynamics in LTO and help understand its superior electrochemical properties.