CVD-assisted fabrication of hierarchical microparticulate Li2TiSiO5-carbon nanospheres for ultrafast lithium storage

Abstract

Particular recent interest has been given to the Li₂TiSiO₅ (LTSO) anode material owing to its low lithiation potential (0.28 V vs. Li/Li⁺) and decent theoretical capacity (308 mA h g⁻¹). However, its poor electronic conductivity (∼10⁻⁷ S m⁻¹) fundamentally limits the utilization of this material, and current strategies fail to tackle such issues in practical ways. Herein, a hierarchical microparticulate LTSO-carbon composite (LTSO/C) is fabricated by chemical vapor deposition (CVD), where microsized LTSO/C particles assembled from nanospheres guarantee a practical tap density of ∼1.3 g mL⁻¹. Meanwhile, significantly elevated conductivity of LTSO/C (∼10³ S m⁻¹) is achieved by a thin layer (15 nm) of graphitic carbon growth on LTSO, which is theoretically catalyzed by the surface functional groups on the parent LTSO. The electrochemical characterization of LTSO/C reveals a superior graphite-like volumetric capacity of 441.1 mA h cm⁻³ and Li₄Ti₅O₁₂-like rate capability (120.1 mA h cm⁻³ at 4.5 A g⁻¹), providing inspiring guidance for designing analogous Ti or Si-based compounds for ultrafast lithium storage materials.