▎ 摘　　要

NOVELTY - Single-crystalline ionically conductive materials are fabricated by forming single-crystalline ionically conductive material on a two-dimensional (2D) material that is disposed over a growth substrate; and removing the single-crystalline ionically conductive material from the growth substrate. USE - Fabrication of single-crystalline ionically conductive materials for use as electrolyte in electrochemical cell (claimed), such as a solid-state battery. ADVANTAGE - The use of the single-crystalline ionically conductive material as an electrolyte may enhance safe and long-cycling of a battery by limiting Li-dendrite penetration and improving Coulombic efficiency by reducing the interface contacting resistance between the single-crystalline ionically conductive material and the 1st electrode and/or the 2nd electrode. The single-crystalline materials grown on graphene substrates can generally be easily and precisely released from the substrate owing to graphene's weak Van der Waals interactions, which permits rapid mechanical release of epitaxially grown layers without post-release reconditioning of the released surface. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for: (1) production of electrochemical cell which involves disposing 1st electrode on 1st side of single-crystalline ionically conductive material; and disposing 2nd electrode on 2nd side of single-crystalline ionically conductive material that is opposite the 1st side of the single-crystalline ionically conductive material; (2) electrochemical cell comprising 1st electrode layer, 2nd electrode layer, and single-crystalline electrolyte between 1st electrode layer and 2nd electrode layer, where total thickness of electrochemical cell is less than or equal to 100 mu m; and (3) single crystalline, freestanding, ionically-conductive layer having a thickness of less than or equal to 100 mu m.