Jafta Charl J, Bridges Craig A, Bai Yaocai, Geng Linxiao, Thapaliya Bishnu P, Meyer Harry M, Essehli Rachid, Heller William T, Belharouak Ilias
Energy and Transportation Science Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA.
Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA.
ChemSusChem. 2020 Jul 22;13(14):3654-3661. doi: 10.1002/cssc.202000802. Epub 2020 Jun 4.
The formation of a solid-electrolyte interphase (SEI) on the surface of Li Ti O (LTO) has become a highly controversial topic, with arguments for it and against it. However, prior studies supporting the formation of an SEI layer have typically suggested that a layer forms upon cycling of a cell, although the layer is probed after disassembling. In this study, cubic mesostructured LTO is synthesized with crystallite domain sizes between 3 and 4 nm and uniform pores with diameters ≤8 nm. The mean pore size is controlled between 4-8 nm through the use of a triblock amphipathic copolymer with a tunable hydrophobic block as template and by thermal treatment. The LTO morphology obtained is spherical and evolves upon heat treatment. These materials show excellent electrochemical performance, including high rate capability and capacity retention. The LTO material is subjected to operando small-angle neutron scattering and X-ray photoelectron spectroscopy experiments, which reveal that the highly debated SEI forms at potentials as high as 2.2 V, first as a LiF-rich layer and subsequently by the growth of a carbonaceous layer. These SEI products form first on the smaller pores before forming on the mesopores.
在LiTi O（LTO）表面形成固体电解质界面（SEI）已成为一个极具争议的话题，存在支持和反对的观点。然而，先前支持SEI层形成的研究通常表明，在电池循环时会形成一层，尽管该层是在拆解后进行探测的。在本研究中，合成了立方介孔结构的LTO，其微晶域尺寸在3至4 nm之间，孔径≤8 nm且均匀。通过使用具有可调节疏水嵌段的三嵌段两亲共聚物作为模板并进行热处理，将平均孔径控制在4 - 8 nm之间。所获得的LTO形态为球形，且在热处理时会发生演变。这些材料表现出优异的电化学性能，包括高倍率性能和容量保持率。对LTO材料进行了原位小角中子散射和X射线光电子能谱实验，结果表明，备受争议的SEI在高达2.2 V的电位下形成，首先形成富含LiF的层，随后是碳质层的生长。这些SEI产物首先在较小的孔隙上形成，然后才在介孔上形成。
