Synthesis and performance of Li4Ti5O12/C with little inert carbon

Highlights: ► Performances of Li4Ti5O12 and Li4Ti5O12/C electrodes without carbon black. ► Li4Ti5O12/C with only 0.47 wt% residual carbon works much better than Li4Ti5O12. ► Metallic Li4Ti5O12 formed during Li ions inter/deinterclation support the performance of Li4Ti5O12 without carbon black at low current rates. ► Conductive Ti (III) or/and residual carbon support the prepared Li4Ti5O12/C without carbon black at higher current rates. ► Though the metallic Li7Ti5O12 formed during lithium ions inter/deintercalation, there are still some spaces to enhance the electrochemical performance of Li4Ti5O12 with proper strategies adopted. - Abstract: Li4Ti5O12/C (LTO/C) is synthesized by solid-state reaction with citric acid added as the conductive carbon source, and the residual carbon is only 0.47 wt%. For comparison, bare LTO is prepared under similar conditions. The electrodes for both samples are prepared without commercial carbon black added. It shows that the LTO/C composite electrodes perform much better than that of LTO. Combined with XRD, XPS, SEM and TEM analysis, it is suggested that the particle size effect could be dismissed, and the main factors influencing the performances should be attributed to the Ti (III) existence and/or the in situ generated residual carbon, both of which are introduced by citric acid. The two main factors influencing the character can not be separated here, but they both improve the conductivity. So, it indicates that with proper strategies to enhance the electronic conductivity of the material, the electrode of spinel lithium titanium oxide with no carbon black added will exhibit better electrochemical behavior, though the metallic Li7Ti5O12 exists