Design of Bronze‐Rich Dual‐Phasic TiO₂ Embedded Amorphous Carbon Nanocomposites Derived from Ti‐Metal–Organic Frameworks for Improved Lithium‐Ion Storage

Abstract

Dual‐phasic (DP)‐TiO2‐based composites are considered attractive anode materials for high lithium‐ion storage because of the synergetic contribution from dual‐phases in lithium‐ion storage. However, a comprehensive investigation on more efficient architectures and platforms is necessary to develop lithium‐storage devices with high‐rate capability and long‐term stability. Herein, for the first time, a rationally designed bronze‐rich DP‐TiO2‐embedded amorphous carbon nanoarchitecture, denoted as DP‐TiO2@C, from sacrificial Ti‐metal–organic frameworks (Ti‐MOFs) via a two‐step pyrolysis process is proposed. The bronze/anatase DP‐TiO2@C nanocomposites are successfully synthesized using a unique pyrolysis process, which decomposes individually the metal clusters and organic linkers of Ti‐MOFs. DP‐TiO2@C exhibits a significantly high density and even distribution of nanoparticles (<5 nm), enabling the formation of numerous heterointerfaces. Remarkably, the bronze‐rich DP‐TiO2@C shows high specific capacities of 638 and 194 mAh g−1 at current densities of 0.1 and 5 A g−1, respectively, owing to the contribution of the synergetic interfacial structure. In addition, reversible specific capacities are observed at a high rate (5 A g−1) during 6000 cycles. Thus, this study presents a new approach for the synthesis of DP‐TiO2@C nanocomposites from a sacrificial Ti‐MOF and provides insights into the efficient control of the volume ratio in DP‐TiO2 anode architecture.

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

“…Successful engineering of bronze/anatase dual-phasic TiO 2 NP embedded in amorphous carbon frameworks (DP-TiO 2 @C), which are efficient anode materials for lithium storage, was achieved from sacrificial MIL-125 via a strategic two-step pyrolysis procedure. 25 This unique two-step pyrolysis process facilitated the formation of heterojunction TiO 2 NP-embedded carbon frameworks via the individual decomposition of metal clusters and organic linkers. The DP-TiO 2 @C showed high specific capacities of 580 mA h g −1 at current densities of 0.1 A g −1 owing to the contribution of the synergetic interface (Figure S1).…”

“…When the composite was applied as an anode material, it displayed ultrahigh specific capacity (638 mA h g −1 ). 25 Given these findings, the MOF-derivation strategy for synthesizing TiO 2 nanoparticles (NPs) was more attractive than other methods because it suppressed the severe aggregation of TiO 2 NPs and formed a conductive carbon framework on the surface of TiO 2 NPs. However, the MOF-derived anode materials did not demonstrate satisfactory specific capacity and rate-capability simultaneously, which inevitably indicates the additional need for a specific electrode design.…”

“…To obtain rationally the bronze-rich DP-TiO 2 @NC, individual pyrolysis processes of metal clusters and organic linkers were employed based on a previous study. 25 NH 2 -MIL-125 platforms prepared with various mixed linker ratios were successfully converted into DP-TiO 2 @NC via individual pyrolysis processes. DP-TiO 2 @NC derived from NH 2 -MIL-125 (H 2 BDC-NH 2 / H 2 BDC = 5:1) showed optimized battery performance, which was attributed to the synergistic storage effect of the nano-heterojunctions in DP-TiO 2 , the efficient lithium-ion diffusion channel provided by the porous carbon network, and the improvement in the electronic conductivity of amorphous carbon networks via efficient nitrogen doping.…”

“…Recently, nano-porous architectures from metal–organic frameworks (MOFs) have emerged as promising synthetic templates for inorganic nanocomposites, which can be helpful in designing efficient active materials for future applications in catalysts, adsorption/separation, and ion storages. − When considering advanced electrode design for high-performance lithium-ion batteries, MOFs can be considered as a promising platform for preparing electrodes. The MOFs can be modified to nanocrystal-embedded carbon frameworks by an in situ topological conversion process, which is an important step in designing an advanced electrode architecture.…”

“…There have also been reports on the MIL-125-derived bronze/anatase dual-phasic TiO 2 (B/A DP-TiO 2 ) composites embedded in carbon obtained through a unique 2-step pyrolysis process. When the composite was applied as an anode material, it displayed ultrahigh specific capacity (638 mA h g –1 ) . Given these findings, the MOF-derivation strategy for synthesizing TiO 2 nanoparticles (NPs) was more attractive than other methods because it suppressed the severe aggregation of TiO 2 NPs and formed a conductive carbon framework on the surface of TiO 2 NPs.…”