Highly-Stable Li4Ti5O12 Anodes Obtained by Atomic-Layer-Deposited Al2O3

Abstract

LTO (Li4Ti5O12) has been highlighted as anode material for next-generation lithium ion secondary batteries due to advantages such as a high rate capability, excellent cyclic performance, and safety. However, the generation of gases from undesired reactions between the electrode surface and the electrolyte has restricted the application of LTO as a negative electrode in Li-ion batteries in electric vehicles (EVs) and energy storage systems (ESS). As the generation of gases from LTO tends to be accelerated at high temperatures (40–60 °C), the thermal stability of LTO should be maintained during battery discharge, especially in EVs. To overcome these technical limitations, a thin layer of Al2O3 (~2 nm thickness) was deposited on the LTO electrode surface by atomic layer deposition (ALD), and an electrochemical charge-discharge cycle test was performed at 60 °C. The capacity retention after 500 cycles clearly shows that Al2O3-coated LTO outperforms the uncoated one, with a discharge capacity retention of ~98%. TEM and XPS analyses indicate that the surface reactions of Al2O3-coated LTO are suppressed, while uncoated LTO undergoes the (111) to (222) phase transformation, as previously reported in the literature.

A low-cost and Li-rich organic coating on a Li4Ti5O12anode material enabling Li-ion battery cycling at subzero temperatures

“…As mentioned above with the Micro-Raman analyses of burned LTO@PTCLi 4 samples, the shape of the 2D band suggests that the carbon coating was composed of a few layers of carbon atoms. 65 If we take into account the reported value for the thickness of a PTCDA monolayer, which is approximately 0.32 nm, 38,66 then the carbon coating should be composed of at least six to seven layers of perylene-like carbon. A rough calculation, considering the largest lattice parameter of the PTCDA monoclinic crystal (P2 1 /c space group, approximately 2 nm), 38 quantity of carbon estimated by TGA (0.89 wt%), and the BET surface area for the LTO sample (see Fig.…”

Characterization of Li Diffusion and Solid Electrolyte Interface for Li4Ti5O12 Electrode Cycled with an Organosilicon Additive Electrolyte

“…Whether a stable SEI can be formed on the surface of an LTO electrode is a debatable topic. [7][8][9] Theoretically, the SEI cannot form on the LTO electrode since its redox potential of 1.55 V vs Li/Li + is above the reduction potential of most electrolytes 10 ; however, many researchers have identified the existence of an SEI on the surface of the LTO electrode using X-ray photoelectron spectroscopy and depth profiling techniques. [11][12][13][14][15][16][17][18] Gauthier et al 11 showed that the SEI on LTO is composed of organic (polyethylene oxides, oxalates) and inorganic species (LiF, phosphates and fluorophosphates), in which the composition and thickness of the SEI are greatly affected when using different electrodes.…”

Temperature Dependence of Electrochemical Degradation in LiNi1/3Mn1/3Co1/3O2/Li4Ti5O12 Cells

“…Rapid capacity fading in NMC–NMC cells has previously been observed at 30 °C and also in NMC442–NMC442 cells cycled at 40 °C, attributed to side‐reactions rather than mechanical degradation . The fading in the LTO–LTO cell is likely related to gas formation, which has been shown to be prominent at elevated temperatures . The low capacity retention and coulombic efficiency in the full cell cycled at 55 °C indicate continuous side‐reactions and that the surface layer formation on the electrodes is not suppressing the parasitic reactions.…”