Well-dispersed Li2CoTi3O8 nanoparticles as a multifunctional material for lithium-ion batteries and lithium-sulfur batteries

Abstract

Cubic spinel Li4Ti5O12 is a desired anode material for lithium-ion batteries (LIBs) due to high stability (the feature of “zero strain”) and good safety. Moreover, Li4Ti5O12 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 Li2CoTi3O8, which not only increases theoretical capacity for LIBs but also enhances the adsorption of sulfur for LSBs. In this paper, Li2CoTi3O8 nanoparticles are synthesized via a sol-gel method. As the anode for LIBs, Li2CoTi3O8 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, Li2CoTi3O8 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 Li2CoTi3O8/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 Li2CoTi3O8 electrode is the result of synergistic effect of dispersed particles and larger contact area for LIBs and LSBs.