Two Steps Li Ion Storage Mechanism in Ruddlesden-Popper Li2La2Ti3O10.

Innovative anode materials are essential for achieving high-energy-density lithium-ion batteries (LIBs) with longer lifetimes. Thus far, only a few studies have explored the use of layered perovskite structures as LIB anode materials. In this study, the study demonstrates the performance and charge/discharge mechanism of the previously undefined Ruddlesden-Popper Li₂La₂Ti₃O₁₀ (RPLLTO) as an anode material for LIBs. RPLLTO exhibits two unique voltage plateaus ≈0.6 and 0.4 V(vs Li/Li⁺), due to the insertion of lithium ions into different sites within its layered structure. The electrical state of Ti is analyzed using X-ray photoelectron spectroscopy and X-ray absorption near edge spectra, revealing a reduction from Ti⁴⁺ to Ti²⁺, corresponding to a capacity of 170 mAh·g⁻¹. In situ X-ray diffraction patterns and extended X-ray absorption fine structure spectra demonstrate the crystal structure changes during lithiation. Complementary expansion along the a/b axes and contraction along the c axis result in a volume change of only 4%. This structural stability is evidenced by an 88% capacity retention after 1000 cycles. This study successfully showcases the lithium-ion storage capability of RPLLTO and contributes to the development of perovskite anode materials with diverse compositions and structures.