Understanding Enhanced Ionic Conductivity in Composite Solid‐State Electrolyte in a Wide Frequency Range of 10^–2–10¹⁰ Hz

Abstract

The ionic conductivity of composite solid-state electrolytes (SSEs) can be tuned by introducing inorganic fillers, of which the mechanism remains elusive. Herein, ion conductivity of composite SSEs is characterized in an unprecedentedly wide frequency range of 10 -2 -10 10 Hz by combining chronoamperometry, electrochemical impedance spectrum, and dielectric spectrum. Using this method, it is unraveled that how the volume fraction v and surface fluorine content x F of TiO 2 fillers tune the ionic conductivity of composite SSEs. It is identified that activation energy E a is more important than carrier concentration c in this game. Specifically, c increases with v while E a has the minimum value at v = 10% and increases at larger v. Moreover, E a is further correlated with the dielectric constant of the SSE via the Marcus theory. A conductivity of 3.1×10 -5 S cm −1 is obtained at 30 °C by tuning v and x F , which is 15 times higher than that of the original SSE. The present method can be used to understand ion conduction in various SSEs for solid-state batteries.

Melamine-Regulated Ceramic/Polymer Electrolyte Interface Promotes High Stability in Lithium-Metal Battery

“…Considering the expression for the ionic conductivity of a composite solid electrolyte σ = C 0 F τ 2 italicRT 0.25em exp ( − E a RT ) the ionic conductivity (σ) is expected to be linearly proportional to the charge-carrier Li + concentration ( C 0 ). We can thus infer that in PEO–MA@LAGP, Li + is released and therefore the concentration of free Li + increases, which leads to an increase in the ionic conductivity …”

“…We can thus infer that in PEO−MA@LAGP, Li + is released and therefore the concentration of free Li + increases, which leads to an increase in the ionic conductivity. 33 To identify the ion conduction mechanism, the interaction between the MA and PEO matrix is investigated via Raman spectroscopy. The characteristic peak located at 281 cm −1 represents a longitudinal acoustic mode ascribed to the motion of the polymeric chain (Figure S9).…”

Opportunities of Flexible and Portable Electrochemical Devices for Energy Storage: Expanding the Spotlight onto Semi-solid/Solid Electrolytes

“…210 A proper combination of these methods is beneficial for the accurate assessment and obtaining a more comprehensive picture of ion transport. 207 Semi-solid/solid electrolytes with high ionic conductivities are highly desired for electrochemical energy devices, which promotes unremitting efforts of the researchers. Taking the semi-solid/solid electrolytes in lithium-based batteries as the examples, the PEO-based SPEs have experienced a long history of development and are regarded as the benchmark which have attracted extensive research interest.…”

“…To isolate the charge transfer contribution of electrons, the alternating current impedance measurements can be supplemented with direct current polarization . A proper combination of these methods is beneficial for the accurate assessment and obtaining a more comprehensive picture of ion transport …”

“…The characterization of ion transport in the semi-solid/solid electrolytes requires coverage of a wide frequency (10 –2 –10 10 Hz). At a frequency of 10 –2 –10 6 Hz, electrochemical impedance spectrum (e.g., alternating current impedance) coupled with ion-blocking electrodes (e.g., platinum, gold, stainless steel) is the most widely utilized approach. , The ion-blocking electrodes are utilized as contacting materials and are required to be inert and stable against the semi-solid/solid electrolytes being tested in the measurement . Specifically, the all-solid-state electrolytes are often sprayed with platinum or gold, and polymer-based electrolytes are usually placed between the stainless-steel plates as ion-blocking electrodes.…”