Abstract
Cubic spinel Li_4Ti_5O_(12) is a desired anode material for lithium-ion batteries (LIBs) due to high stability (the feature of "zero strain") and good safety. Moreover, Li_4Ti_5O_(12) has a good affinity with sulfur for restraining lithium polysulfides (LiPSs) by the Ti-S bond in lithium-sulfur batteries (LSBs). Interestingly, extra cobalt element is introduced to form Li_2CoTi_3O_8, which not only increases theoretical capacity for LIBs but also enhances the adsorption of sulfur for LSBs. In this paper, Li_2CoTi_3O_8 nanoparticles are synthesized via a sol-gel method. As the anode for LIBs, Li_2CoTi_3O_8 displays a desired specific capacity (335.3 mAh g~(-1) at 0.2 A g~(-1)) and a better rate-capability (188.5 mAh g~(-1) at 5 A g~(-1); no capacity decay over 400 cycles), which is superior to electrochemical performances of the reported same substances. Besides, Li_2CoTi_3O_8 nanoparticles are designed as both the sulfur host material and the modified separator in LSBs for the first time. Under the LCTO-coated separator, the Li_2CoTi_3O_8/S electrode achieves a first capacity of 1048 mAh g~(-1) at 0.5 C and the stable capacity retention (732.7 mAh g~(-1) after 100 cycles). The enhanced performance of the Li_2CoTi_3O_8 electrode is the result of synergistic effect of dispersed particles and larger contact area for LIBs and LSBs.
NSTL
Elsevier