Promotional role of Li4Ti5O12 as Li+ conductor and structural stabilizer on Sn@C anode cyclability

Nano-Sn confined to matrixes for fabricating high capacity and long cycle life anodes has attracted extensive attention in recent years, but using Li+ conductor as structure stabilizer to construct matrixes have not been studied yet. Sn-based anodes using spinel Li4Ti5O12 as Li+ conductor and structure stabilizer can prolong the cycle life of electrodes, which is due to "zero strain" property and high Li+ conductivity coefficient of Li4Ti5O12. Herein, spherical (nano-Sn/Li4Ti5O12)@C was designed, synthesized and investigated, which was labeled as (n-Sn/L)@C. Nano-Sn and nano-Li4Ti5O12 pieces were mixed uniformly in inner carbon shell, where some vacuum space was beneficial for Sn expanding/shrinking during Li+ insertion/extraction. Moreover, Li+ diffusion coefficient of (n-Sn/L)@C-1 and (n-Sn/Q@C-2 was high as 6.09 x 10(-8) and 9.47 x 10(-9) cm(2) s(-1), whereas the value of Sn@C was 7.54 x 10(-10) cm(2) The charge capacity (corresponding to the reversible capacity on full cell) loss of per cycle of (n-Sn/L)@C-1 and (n-Sn/L)@C-2 from 1st to 350th cycle was only 0.081% and 0.094% at 500 mA g(-1), while the value of Sn@C was 0.160%. The enhanced electrochemical performances of (n-Sn/L)@C benefited from intimate contact of nano-Li4Ti5O12 and nano-Sn within the carbon shell, and high Li+ conductivity of Li4Ti5O12. (C) 2017 Elsevier B.V. All rights reserved.