Optical, morphological properties and surface energy of the transparent Li₄Ti₅O₁₂ (LTO) thin film as anode material for secondary type batteries

Abstract

LTO thin film was deposited for the first time on a glass microscope slide (MS) by RF magnetron sputtering technology. This method has been suitable for preparation of high-quality thin films. The surface properties of the produced film were determined by atomic force microscope (AFM). The surface of the produced film appeared smooth and homogeneous. LTO coated on MS had compact structure and low roughness. A UV–vis spectrophotometer was used to determine intensity of light passing through the samples. Thus, according to the results obtained the produced film was highly transparent. The refractive index of the LTO thin film was presented in a low MSE value by spectroscopic ellipsometry (SE) and it was about 1.5. The optical band gap (E g) was determined by the Tauc method. The produced LTO thin film exhibited a wide band gap semiconductor property with a band gap energy of about 2.95 eV. Finally, the surface free energy of the LTO thin film was calculated from the contact angle measurements using the Lewis acid-base, OWRK/Fowkes, Wu and Zisman methods.

Featured properties of Li+-based battery anode: Li4Ti5O12

“…This band gap is close to the values of the theoretical results, which are 3.015 eV 56 and 2.52 eV, 16 and to the experimental result of 2.95 eV. 57 Plenty of valence and conduction energy subbands exist because of the many atoms and outer orbitals in a large unit cell. Generally speaking, the energy dispersions are weak but signicant.…”

Enhancing Ultrafast Lithium Ion Storage of Li4Ti5O12 by Tailored TiC/C Core/Shell Skeleton Plus Nitrogen Doping

“…Compared to LTO@TiC/C, the spectrum of N‐LTO@TiC/C presents stronger absorption at wavelength from 230 to 800 nm, with a broad absorption peak at about 275 nm. Furthermore, the bandgap ( E g ) of LTO could be calculated from the following equationwhere α, hυ , and C are absorption coefficient, the energy of the scanning source light, and a coefficient, respectively. According to Figure c, we can conclude that the E g of N‐LTO is decreased from 3.18 to 2.88 eV after N‐doping, resulting in enhanced electronic conductivity.…”

Multifunctional Batteries: Flexible, Transient, and Transparent

“…The second strategy is to reduce the dimensions of active materials and decrease the electrode thickness down to a scale below their optical absorption length. 122 In Figure 5 a–e, Roeder et al applied a sol–gel dip-coating technique to prepare a transparent full cell battery consisting of a 600 nm thick Li 4 Ti 5 O 12 anode and a 150 nm thick LiMn 2 O 4 cathode. 123 Li 4 Ti 5 O 12 presented a visible light transmittance of 30–75%, transitioning from dark-blue to colorless depending on the charge/discharge state.…”