Interfacial Atomic Structures of Single-Phase Li₂MnO₃Thin Film with Superior Initial Charge-Discharge Behavior

Li 2 MnO 3 film synthesized on SrTiO 3 substrate with SrRuO 3 buffer layer using pulsed laser deposition has demonstrated a high initial charge-discharge capacity. It has been found that the Li 2 MnO 3 crystals were composed of nano-domains with 5 nm in size, which followed a dominant orientation relationship (OR) with respect to the SrRuO 3 crystals at the Li 2 MnO 3 /SrRuO 3 interface. The domain size is in agreement with the calculated critical size, which is determined by the elastic strain originated from the lattice mismatch at the Li 2 MnO 3 /SrRuO 3 interface. We proposed that the high initial charge-discharge capacity of the Li 2 MnO 3 film is due to the combined effects of (1) being able to release the lattice strain at the Li 2 MnO 3 domain boundaries during (de)intercalation of Li-ions that causes lattice expansion and shrinkage, and (2) crystal structure of the nano-domains and their ORs with respect to the SrRuO 3 crystals being well-maintained due to the above strain release. In addition, our observation confirmed the existence of anti-phase domain boundaries and stacking faults in the Li 2 MnO 3 crystals. However, it is considered that their influences on the (de)intercalation of Li-ions are not significant, because these defects do not obstruct the conduction paths of Li atoms that are orderly arranged in the c -planes.