High dispersion of TiO2 nanocrystals within porous carbon improves lithium storage capacity and can be applied batteries to LiNi0.5Mn1.5O4

Abstract

A new and simple strategy was developed to effectively disperse titanium dioxide (TiO₂) nanocrystals into porous carbon (PC), and a series of hierarchical PC–TiO₂ composites with different architectures were synthesized. By varying the amount of TiO₂, from 30 wt% to 64 wt%, the lithium storage capacity of PC–TiO₂ could be controllably varied from 546 mA h g⁻¹ to 446 mA h g⁻¹ under a current density of 50 mA g⁻¹. Also, very stable cycling performances and rate capabilities could be obtained at the rates of 50 mA g⁻¹ to 1600 mA g⁻¹. By further increasing the content of TiO₂ to 93%, another new composite of TiO₂–C was also prepared and it demonstrated a storage capacity of 352 mA h g⁻¹ at 50 mA g⁻¹, which is much higher than that for most reported TiO₂ materials. Based on these results, new full cells with a LiNi_0.5Mn_1.5O₄ cathode, such as PC–TiO₂/LiNi_0.5Mn_1.5O₄, were successfully assembled and investigated. This full cell not only delivered a high energy density of 413 W h kg⁻¹ but also showed a good rate capability and an energy retention of 90.5% over 100 cycles.