TiO₂ Nanocrystal-Framed Li₂TiSiO₅ Platelets for Low-Voltage Lithium Battery Anode

Titanium-based anode materials are attracting considerable attention for use in high-performance lithium-ion batteries, but the compromised energy density caused by high voltage plateaus and unsatisfactory capacities severely retards their practical applications. Herein, a molten-salt synthesis of Li₂TiSiO₅ crystalline platelets and a subsequent selective facet modification by in situ growth of TiO₂ nanocrystal frames are facilely achieved. The discharge voltage plateau at around 0.5 V renders the Li₂TiSiO₅ anode safe compared with graphite and confers a high energy density compared with zero-strain Li₄Ti₅O₁₂ anode. With the optimized size, structure, and content of modified TiO₂ nanocrystals associated with the exposed (001) plane of Li₂TiSiO₅, the Li₂TiSiO₅-based anodes can deliver a capacity of above 300 mAh g⁻¹, enhanced rate performance, and a capacity retention of 66% after 10 000 cycles. In situ X-ray diffraction and ex situ transmission electron microscopy have demonstrated the structural stability of the anodes upon charge/discharge. Further theoretical calculation reveals 3D migration paths of Li⁺ ions in Li₂TiSiO₅. The selective modification of in situ grown TiO₂ nanocrystals on certain facets of crystallites opens a new door for the development of electrode materials possessing superior electrochemical properties.