Impedance Spectroscopy Analysis of the Lithium Ion Transport through the Li₇La₃Zr₂O₁₂/P(EO)₂₀Li Interface

Abstract

Model systems for electrochemical impedance spectroscopy (EIS) studies of solid-state electrolytes based on ceramic lithium ion conductor Li 7 La 3 Zr 2 O 12 (LLZO) and polymer electrolyte P(EO) 20 -LiClO 4 are investigated for the first time. The aim of the present study is to identify and quantify the lithium ion transition resistance of the ceramic/polymer interface. Symmetrical model systems consisting of LLZO pellets with sheets of P(EO) 20 -LiClO 4 are manufactured and investigated in detail. In such symmetric model systems we observed an additional ion-transfer process, which we attributed to the interface processes (i.e. distributed Li + transition across the interface). Based on the EIS measurement data obtained above the polymer electrolyte's melting temperature, at 70 • C the interface resistance of the lithium ion transition is estimated to be ∼9 k cm 2 and the capacitance of the process is in the order of 0.1 μF/cm 2 . According to our investigations, it is possible to predict interface resistivity of lithium ion transport for different polymer/ceramic composite electrolytes for solid state lithium battery applications.

From Liquid- to Solid-State Batteries: Ion Transfer Kinetics of Heteroionic Interfaces

“…The activation energy of the PE/SE interface in case of lithium-ion conductors is determined around 1 eV in three independent studies with different PE/SE combinations [52,55,58]. For example, Abe et al investigated the interface between LLTO and PEO complexed with LiTf using twopoint EIS measurements [52].…”

“…In a recent study [58], it was shown that a porous interface str ucture between LLZO and PEO 20 ∶LiClO 4 (EO∶Li + = 20∶1) resulted in a significantly increased resistance while the activation energy was similar to the LLTO/PE discussed above [52]. Fitting the recorded EIS data with a de Levie element-a transmission line model generally used for porous electrodes [68,69]-enabled the distinction between pore and ion transition contributions [58].…”

“…Keeping the direct contact between the PE and the SE is essential to mitigate penalties in the ion transport resistance due to contact loss. Therefore, hot-pressing procedures [56] and sputtering techniques [55] proved to be viable methods to decrease the interface resistance compared to stacked SE/PE setups [52,58].…”

“…Compared to the SE/LE interface, the interfacial resistance and the energy barrier for the ion transport between the SE and the PE are mostly both higher [41]. In most of the published work, the interface resistance and activation energy were reported [41,44,[52][53][54][55][56][57][58], whereas the interface chemistry has been investigated only partially so far.…”

Melt crystallization and segmental dynamics of poly(ethylene oxide) confined in a solid electrolyte composite

“…Although the scattering pattern of linear PEO may also exhibit other Bragg reflections such as (024) and (131) at 26.4° and 27.1°, in our results they are not notable. When adding LLZO into PEO, more peaks also arise as LLZO has a cubic garnet structure such as at 16.6°, 25.6°, 27.4°, and 19.3° which overlaps PEO. Comparison of WAXS spectra of crystallized PEO and LLZO particles can be found in the Supporting Information Figure S4.…”