Nitrogen-Doped Amorphous Carbon/Dual-Phasic TiO2 Nanocomposite Electrodes Derived from Ti-Based Metal–Organic Frameworks Designed with a Mixed Linker Combination for High-Rate Lithium Storage

The development of high-capacity and high-rate electrode architectures is key to improving the performance of rechargeable lithium-ion batteries. However, developing an electrode design technology that satisfies the requirements of both high capacity and high rate capability remains challenging. Herein, we propose a creative synthesis design approach that controls the bronze/anatase dual-phasic TiO2-embedded nitrogen-doped amorphous carbon nanocomposite (DP-TiO2@NC) architecture, which was derived from a mixed linker NH2-MIL-125 platform via a unique two-step pyrolysis process. The rationally controlled mixed ligands were based on H2BDC-NH2 and H2BDC and demonstrated the ability to tune the nitrogen-doping configuration of amorphous carbon frameworks, thereby enhancing the electronic conductivity of the carbon frameworks. Remarkably, DP-TiO2@NC derived from NH2-MIL-125 using a 5:1 ratio of H2BDC-NH2/H2BDC showed optimized battery performance (595 mA h g–1@0.1 A g–1 and 250 mA h g–1@10 A g–1) due to the improved electronic conductivity of the amorphous carbon framework and the synergetic storage effect of the nano-heterojunctions in DP-TiO2. In addition, mixed linker MIL-125-derived DP-TiO2@NC electrodes showed an excellent capacity retention of 95% even under harsh conduction [10 A g–1 (≈30 C)] after 6000 cycles. This study demonstrates that the mixed ligand strategy for metal–organic framework-derived electrodes is a highly useful approach for designing efficient electrode architectures.