Thin-Film Calorimetry: Analytical Tool for In-Situ Characterization of Lithium Ion Batteries

Abstract

Thin-Film Calorimetry (TFC) as presented in this work is a novel analytical tool to determine phase transformation temperatures and enthalpies of thin films and thin-film sequences. The key component is a high-temperature stable piezoelectric langasite (La 3 Ga 5 SiO 14 ) resonator serving as a highly sensitive planar temperature sensor. Deviations in its frequency are related to temperature fluctuations caused by phase transformations and used to calculate the related enthalpies. Temperature ramps from room temperature up to 1000 • C are applied to perform calorimetric thin-film investigations. Thereby, the atmosphere can be controlled. To the best of our knowledge, the presented TFC is the only existing technique combining the aspects "thin films" and "high-temperature calorimetry." The first part of this article describes the newly developed TFC system. The second part presents TFC investigations on lithium manganese oxide (LMO) thin films. Measurements are carried out in ambient air and in 0.5 %H 2 /Ar. In air three phase transformations appear (at 330, 410 and 600 • C) while in 0.5 %H 2 /Ar four phase transformations are observed (at 389, 471, 730 and 758 • C). Their progression and related enthalpies are discussed. To determine the associated crystallographic phases, X-ray diffraction and Raman spectroscopy are performed.

Preparation and Characterization of c‐LiMn2O4 Thin Films prepared by Pulsed Laser Deposition for Lithium‐Ion Batteries

“…The reasons for these differences are still not fully understood. In publications focused on these phase transformations, it is reported that the stoichiometric spinel phase crystallizes from different parent phases in different atmospheres, even though the starting composition is the same. The TFC results show that the phase mixture in the low‐ p O2 atmosphere has a higher thermal stability than the over‐stoichiometric spinel, which is the parent phase in the atmosphere with higher oxygen partial pressure.…”

“…The TFC results show that the phase mixture in the low‐ p O2 atmosphere has a higher thermal stability than the over‐stoichiometric spinel, which is the parent phase in the atmosphere with higher oxygen partial pressure. A detailed introduction to the technique and detailed results of the LMO characterization are published elsewhere . These results are in good agreement with the annealing behavior of the PLD‐deposited LMO films presented here, where a single‐phase sample is prepared at an annealing temperature of 700 °C, which is in between the two values from TFC characterization.…”

“…In publications focused on these phase transformations, [15,16] it is reported that the stoichiometric spinel phase crystallizes from different parentp hases in different atmospheres,e ven though the startingc ompositioni s the same.T he TFC results show that the phase mixture in the low-p O2 atmosphere has ah igher thermal stability than the over-stoichiometric spinel, which is the parentp hase in the atmosphere with higher oxygenp artialp ressure.Adetailed introductiont ot he technique and detailed resultso f the LMO characterization arep ublished elsewhere. [15,16] These results are in good agreement with the annealing behavioro ft he PLD-deposited LMO films presented here, where asingle-phasesample is prepared at an annealing temperatureo f7 00 8C, which is in between the two valuesf rom TFC characterization. As these resultsw ere obtained in ap ure Ar-atmosphere (medium p O2 )t he transition temperature is expected to be between 600 8C( high p O2 )a nd 785 8C (low p O2 ), as confirmed by the XRDanalysis.…”

D4.3 - Thin-film calorimeter for high-temperature applications: Thermodynamic characterization on piezoelectric langasite temperature sensors

“…The Thin-Film Calorimeter (TFC) is a measurement system for the determination of temperature and enthalpy of phase transformations (PT) of thin films. Its suitability to provide thermodynamic data in the field of LIB materials has been demonstrated [9], [10], [11], [12]. It uses piezoelectric langasite (La3Ga5SiO14, LGS) resonators which serve as planar temperature sensors.…”

Thin-film nano-thermogravimetry applied to praseodymium-cerium oxide films at high temperatures

“…Similar stress effects have been noted at phase transformations that are accompanied by large volume changes. 21 To exclude or reduce the effect of mechanical deflection stress, PCO films of nearly identical thicknesses were deposited on both sides of the resonators.…”