Pathway\nto High Rate Capability in Interconnected\nComposite Electrolytes: A Case Study with a Single-Ion-Conducting\nPolymer

In\na three-dimensional interconnected polymer/ceramic composite\nelectrolyte (3D composite), both the polymer and ceramic electrolyte\nphases are individually connected with a polymer-rich surface layer\nto provide conformal contact with the electrodes. This work investigates\nhow the transference number of the polymer phase affects the electrochemical\nproperties of the 3D composite. Here, we fabricate a 3D composite\nusing a “single-ion” conducting polymer electrolyte\n(PE), Li<sub>1+<i>x</i>+<i>y</i></sub>Al<sub><i>x</i></sub>Ti<sub>2–<i>x</i></sub>Si<sub><i>y</i></sub>P<sub>3–<i>y</i></sub>O<sub>12</sub> (LICGC) ceramic, and compare its electrochemical properties with\nthe neat polymer, and with a 3D composite made with a dual-ion-conducting\nPE (we reported previously). Our results reveal that changing the\npolymer phase from a dual-ion-conducting PE to a single-ion-conducting\nPE results in a 9-fold increase in the limiting current density, although\nthe interfacial impedance between the polymer and LICGC ceramic remains\nhigh (and contributes significantly to the total impedance of the\n3D composite). The limiting current density of the 3D composite is\ndictated by the PE and minimally affected by the ceramic scaffold.\nThe ceramic scaffold, however, helps to ease the concentration gradient\nbuildup within the PE and moderately improves the overall transference\nnumber. The LICGC scaffold does not provide any additional Li dendrite\nresistance due to its high reactivity with Li.