Li₄Ti₅O₁₂/graphene nanoribbons composite as anodes for lithium ion batteries

In this paper, we report the synthesis of a Li₄Ti₅O₁₂/Graphene Nanoribbons (LTO/GNRs) composite using a solid-coating method. Electron microscope images of the LTO/GNRs composite have shown that LTO particles were wrapped around graphene nanoribbons. The introduction of GNRs was observed to have significantly improved the rate performance of LTO/GNTs. The specific capacities determined of the obtained composite at rates of 0.2, 0.5, 1, 2, and 5 C are 206.5, 200.9, 188, 178.1 and 142.3 mAh·g⁻¹, respectively. This is significantly higher than those of pure LTO (169.1, 160, 150, 106 and 71.1 mAh·g⁻¹, respectively) especially at high rate (2 and 5 C). The LTO/GNRs also shows better cycling stability at high rates. Enhanced conductivity of LTO/GNRs contributed from the GNR frameworks accelerated the kinetics of lithium intercalation/deintercalation in LIBs that also leads to excellent rate capacity of LTO/GNRs. This is attributed to its lower charge-transfer resistance (Rct = 23.38 Ω) compared with LTO (108.05 Ω), and higher exchange current density (j = 1.1 × 10⁻³ mA cm⁻²)—about 20 times than those of the LTO (j = 2.38 × 10⁻⁴ mA cm⁻²).