Phase stability of N substituted Li2-xFeSiO4 electrode material: DFT calculations

作者：Zhu, Lin; Li, Lin^*; Xu, Lin-Han; Cheng, Tai-Min

来源：Computational Materials Science, 2015, 96: 290-294.

DOI：10.1016/j.commatsci.2014.09.012

• Fe-based silicates
• Cathode material
• Phase stability
• DFT calculation

First principles calculations are used to focus on the phase stability of N substituted Li2FeSiO4. The ground state structures of Li-2 xFeSiO4 N-y(y) (x = 0,1,2; y = 0.5, 1) are determined by including the site-exchange of Li and Fe, on the basis of the Pmn2(1) structure of Li2FeSiO4. Calculated B/G (quotient of bulk to shear modulus) values of delithiated FeSiO4 N-y(y) are 1.33 (y = 0.5) and 0.94 (y = 1) lower than the critical value 1.75 which separates ductile and brittle materials. The elastic-brittle FeSiO4 N-y(y) would induce a structural collapse and a capacity fading of Li2FeSiO(4) N-y(y) during the charge/discharge cycles, under a significant volume change of more than 32.0%. The calculated results suggest that the phase stability is important for the electrochemical performance of Fe-based silicates as well as the deinsertion voltage.

• 出版日期2015-1
• 单位沈阳化工大学; 东北大学