Two-Dimensional Films Based on Graphene/Li4Ti5O12 and Carbon Nanotube/Li4Ti5O12 Nanocomposites as a Prospective Material for Lithium-Ion Batteries: Insight from Ab Initio Modeling

The combination of spinel Li₄Ti₅O₁₂ (LTO) with carbon nanostructures, such as graphene (G) and carbon nanotubes (CNTs), provides all of the required properties for modern chemical power sources such as Li-ion batteries (LIBs) and supercapacitors (SCs). G/LTO and CNT/LTO composites demonstrate a superior reversible capacity, cycling stability, and good rate performances. In this paper, an ab initio attempt to estimate the electronic and capacitive properties of such composites was made for the first time. It was found that the interaction between LTO particles and CNTs was higher than that with graphene due to the larger amount of transfer charge. Increasing the graphene concentration raised the Fermi level and enhanced the conductive properties of G/LTO composites. For CNT/LTO samples, the radius of CNT did not affect the Fermi level. For both G/LTO and CNT/LTO composites, an increase in the carbon ratio resulted in a similar reduction in quantum capacitance (QC). It was observed that during the charge cycle in the real experiment, the non-Faradaic process prevailed during the charge cycle, while the Faradaic process prevailed during the discharge cycle. The obtained results confirm and explain the experimental data and improve the understanding of the processes occurring in G/LTO and CNT/LTO composites for their usages in LIBs and SCs.

Nano/micrometer porous conductive network structure Li4Ti5O12@C/CNT microspheres with enhanced sodium-storage capability as an anode material

Li₄Ti₅O₁₂@C/CNT microspheres, wherein CNTs were firmly anchored to Li₄Ti₅O₁₂@C nanoparticles, were prepared via a facile spray drying method and subsequently annealed in an argon atmosphere, exhibiting long cycling stability (charge/discharge capacities of 85.45/86.18 mA h g⁻¹ after 500 cycles at 500 mA g⁻¹) and excellent rate capability (charge capacity of 61.16 mA h g⁻¹ after 10 cycles at 1000 mA g⁻¹). The special spherical structure design is not only beneficial to improving the structural stability and reaction kinetics of the electrode materials during the long-term extraction–insertion of sodium ions but also supplies numerous interfacial sites to store more sodium ions.

Li₄Ti₅O₁₂@C/CNT microspheres were prepared by a facile spray drying method, which exhibited long cycling stability (85.45 mA h g⁻¹ after 500 cycles at 500 mA g⁻¹) and excellent rate capability (61.16 mA h g⁻¹ after 10 cycles at 1000 mA g⁻¹).

Mesoporous Li4Ti5O12 nanoclusters anchored on super-aligned carbon nanotubes as high performance electrodes for lithium ion batteries

Mesoporous lithium titanate (LTO) nanoclusters are in situ synthesized in a network of super aligned carbon nanotubes (SACNTs) via a solution-based method followed by heat treatment in air. In the LTO-CNT composite, SACNTs not only serve as the skeleton to support a binder-free electrode, but also render the composite with high conductivity, flexibility, and mechanical strength. The homogeneously dispersed LTO nanoclusters among the SACNTs allow each LTO grain to effectively access the electrolyte and the conductive network, benefiting both ion and electron transport. By the incorporation of LTO into the CNT network, mechanical reinforcement is also achieved. When serving as a negative electrode for lithium ion batteries, such a robust composite-network architecture provides the electrodes with effective charge transport and structural integrity, leading to high-performance flexible electrodes with high capacity, high rate capability, and excellent cycling stability.