Study on Bronze-Rich Dual-Phasic TiO₂ Embedded Carbon Architecture Derived from Ti-Metal-Organic Frameworks for Enhanced Lithium-Ion Storage

Lithium-ion batteries (LIBs) are widely used for energy storage due to their affordability, rechargeability, long cycle life, and high energy density. Currently, graphite, as an anode material, faces limitations in constructing high-capacity LIBs due to its low theoretical capacity (372 mAh/g) and safety concerns. TiO₂ is considered a promising alternative due to its abundance, cost-effectiveness, high discharge voltage plateau, and minimal volume change (&lt;3%). However, TiO₂ has a relatively low theoretical capacity and practical capacity issues, with the actual capacity often lower than theoretical values. Nanostructured TiO₂ has been shown to significantly improve lithium insertion rates to over 75%. Moreover, interest in bronze TiO₂ nanostructures has grown due to their high theoretical capacity of 420 mAh/g. Recently, strategies involving dual-phase nanostructures are anticipated to enhance both capacity and rate capability.<br/>Metal–Organic Frameworks (MOFs), composed of metal elements and organic linkers, have emerged as promising materials for catalysts, electrodes, and energy storage devices due to their porous architecture and catalytic sites. Ti-based MOFs, in particular, can be converted into porous carbon materials containing TiO₂ nanoparticles. This study introduces a novel approach using Ti-based MOFs to create a bronze-rich dual-phase TiO₂ embedded in carbon architecture via a two-step pyrolysis process. During the first pyrolysis step, metal clusters decompose to form intermediate phases, facilitating the synthesis of bronze TiO2 crystals. In the second step, the resulting dual-phase TiO₂ is integrated into a conductive amorphous carbon matrix.<br/>This method demonstrates a specific capacity of 638 mAh/g at a current density of 0.1 A/g and 194 mAh/g at 5 A/g, highlighting the contribution of interfacial storage. Additionally, the proposed bronze-rich dual-phase TiO₂ embedded in carbon architecture derived from Ti-MOFs exhibits stable reversibility at high-rate densities over 6000 cycles.