Ionic Conduction in Composite Polymer Electrolytes: Case of PEO:Ga-LLZO Composites

Abstract

By dispersing Li6.25Ga0.25La3Zr2O12 (Ga-LLZO) nanoparticles in poly­(ethylene oxide) (PEO) matrix, PEO:Ga-LLZO composite polymer electrolytes are synthesized. The PEO: Ga-LLZO composite with 16 vol % Ga-LLZO nanoparticles shows a conductivity of 7.2 × 10–5 S cm–1 at 30 °C, about 4 orders of magnitude higher than the conductivity of PEO. The enhancement of the ionic conductivity is closely related to the space charge region (∼3 nm) formed at the interface between the PEO matrix and the Ga-LLZO nanoparticles. The space charge region is observed by transmission electron microscope (TEM) and corroborated by the phase-field simulation. Using the random resistor model, the lithium-ion transport in the composite polymer electrolyte is simulated by the Monte Carlo simulation, demonstrating that the enhanced ionic conductivity can be ascribed to the ionic conduction in the space charge regions and the percolation of the space charge regions.

Intermolecular Chemistry in Solid Polymer Electrolytes for High‐Energy‐Density Lithium Batteries

“…Therefore, ceramic fillers with Lewis acidic surface groups are better for the improvement of ionic conductivity and lithium ion transference number. As the content of Al 2 O 3 increased to 20%, these intermittent coordinations can provide a continuous pathway for the transport of the charge carriers, which was named as the percolation behavior of composite polymer electrolyte . In order to take advantage of the percolation behavior along interface, Y 2 O 3 ‐doped ZrO 2 (YSZ) nanowires with a low oxidation state was used to create high concentration of oxygen vacancies ( Figure a).…”

Recent Progress in Organic–Inorganic Composite Solid Electrolytes for All‐Solid‐State Lithium Batteries

“…[31a] On the other hand, according to the percolating interfacial effect, anions within the composite electrolytes are usually adsorbed on the surface of ceramic fillers, which can break up the ion pair;t hus leading to the increase of ionic conductivity. [96] [97] this showeda ni mproved ionic conductivity of 7.2 10 À4 Scm À1 , which was about four orders of magnitude higher than that of the pure PEO-based electrolyte. The enhancement in ionic conductivity was mainly ascribed to ionic conduction and percolation in the space charge region, which formed at the interface between the polymer and Ca-doped LLZO NPs (Figure 8a).…”

“…Ther esulting composite electrolyte delivers a series of favorable electrochemical properties,i ncluding ah igh room-temperature ionic conductivity of 2 10 À4 Scm À1 ,awide electrochemical window of 4.5 V, improved Li + transport number of 0.6, and good compatibility with the Li-metal anode.T he Li/LiFe 0.2 Mn 0.8 PO 4 ASSB shows ah igh specific capacity of 130 mA hg À1 and outstanding cyclings tabilityo ver 140 cycles at 0.5 C. Villaluenga et al developedn onflammable glass-polymer hybrid single-ion-conducting composite electrolytes. [101] The hybrid electrolytes comprised inorganic sulfide [97] c) Schematicillustration of PEO-LLZTO CSEsof" ceramic-in-polymer" to "polymer-in-ceramic" types. [20] d) Schematicillustrationo fL i-ion pathways within the LLZO-PEOC SEs.…”

Composition Modulation and Structure Design of Inorganic‐in‐Polymer Composite Solid Electrolytes for Advanced Lithium Batteries

“…The oxygen vacancies on/near the filler surface are positively charged, and they can act as Lewis acid sites to couple strongly with the anions of Li salt, thus releasing positively charged Li ions for the fast Li + ‐transport along the nanowire surface area ( Figure a). Further, to clarify the interfacial percolation effect in the composite polymer electrolyte, Li et al developed a percolation model based on the two‐phase mixture theory. In their study, the researchers uncovered that there are space charge regions forming at the interface of polymer matrix and active fillers, in which are a fast conduction pathway for Li ions (Figure b).…”

“…c) Comparison of the ionic conductivity data obtained from the simulation and the experimental measurement for the PEO/LLZO composite solid electrolyte. Reproduced with permission . Copyright 2019, American Chemical Society.…”