Structure of Surface Entrance Sites for Li Intercalation into TiO2 Nanoparticles, Nanosheets, and Mesoporous Architectures with Application for Li-Ion Batteries

• Published in: Journal of physical chemistry. C Vol. 120; no. 26; pp. 14001 - 14008
• Main Authors: Matshaba, Malili G, Sayle, Dean C, Sayle, Thi X. T, Ngoepe, Phuti E
• Format: Journal Article
• Language: English
• Published: American Chemical Society 07.07.2016
• ISSN: 1932-7447; 1932-7455
• DOI: 10.1021/acs.jpcc.6b04770

Power output is central to the viability of a Li-ion battery and is, in part, dependent upon the activation energy barrier associated with Li intercalation/deintercalation into the host lattice (electrode). The lower the energy barrier, the faster the intercalation reaction rate and greater the power. The activation energy is governed by the atomistic structure(s) of the entrance sites for Li intercalation. Accordingly, a first step in optimizing battery power via structural manipulation of entrance sites is to understand the structure of these entrance sites. However, HRTEM is (presently) unable to characterize the structures of entrance sites with atomistic resolution. Accordingly, we generate models of the entrance sites using molecular dynamics. In particular, we simulate the synthetic protocol used to fabricate nanostructured TiO2 experimentally. The resulting atomistic models reveal a highly complex and diverse structural distribution of entrance sites, which emanate from the surface curvature of the nanostructured material. In particular, we show how nanostructuring can be used to change profoundly the nature and concentration of such entrance sites.