Enhanced rate performance of Li4Ti5O12 anodes with bridged grain boundaries

JOURNAL OF POWER SOURCES

卷:354

Article

Feng, Xu-Yong^1,3  Li, Xiang¹  Tang, Mingxue^1,2  Gan, Alberic⁴  Hu, Yan-Yan^1,2 

[1] Florida State Univ, Dept Chem & Biochem, Tallahassee, FL 32306 USA

[2] Natl High Magnet Field Lab, Ctr Interdisciplinary Magnet Resonance, 1800 East Paul Dirac Dr, Tallahassee, FL 32310 USA

[3] Hefei Univ Technol, Sch Mat Sci & Engn, Hefei 230009, Anhui, Peoples R China

[4] Lawton Chiles High Sch, 7200 Lawton Chiles Ln, Tallahassee, FL 32312 USA

关键词: Lithium-ion battery;    Lithium titanium oxide;    Solid-state NMR;    Grain boundary;   

DOI  :  10.1016/j.jpowsour.2017.04.032

来源: Elsevier

【 摘 要 】

Excellent rate performance of Li4+xTi5O12 (0 < x < 3, LTO) electrodes results from mixed Li site occupancy and facile Li ion exchange at 8a and 16c sites. In this paper, we reveal that inter-particle connectivity within LTO electrodes affects 8a and 16c site occupancies upon discharge and impacts Li ion diffusion. LTO electrodes of the same primary crystal structure but of different grain boundary structures were prepared and they showed significantly different electrochemical performance. LTO electrodes with a percolated 3D structural network and bridged grain boundaries offered balanced 8a-16c occupancy, Li ion exchange at 8a and 16c sites upon discharge, high ionic conductivities, and good rate performance. While LTO electrodes with isolated clusters of particles showed strong rate dependence of 8a-16c occupancy, a lack of Li ion exchange at 8a and 16c sites, large over-potential, and substantial capacity decay upon fast charging. Bridged grain boundaries in LTO secondary particles facilitate apparent solid-solution process during electrochemical cycling by maintaining Li site exchange and thus enhance the rate performance of LTO electrodes. (C) 2017 Elsevier B.V. All rights reserved.

【 授权许可】

Free