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 nitrogendoped amorphous carbon nanocomposite (DP-TiO2@ NC) architecture, which was derived from a mixed linker NH2-MIL125 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) (approximate to 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.

Automated summary

This study proposes a new synthesis design approach to control the DP-TiO2@NC architecture, derived from a two-step pyrolysis process, for developing electrodes that meet the requirements of high capacity and high rate capability. By tuning the configuration of mixed ligands, the electronic conductivity of the carbon frameworks can be enhanced, resulting in improved battery performance.