High rate performance of the composites of Li4Ti5O12–Ketjen Black and Li4Ti5O12–Ketjen Black–multi-walled carbon nanotubes for Li-ion batteries

Composites of Li4Ti5O12–Ketjen Black (Li4Ti5O12–KB) and Li4Ti5O12–Ketjen Black–multi-walled carbon nanotubes (Li4Ti5O12–KB–MWCNTs) are prepared by a simple solution method. Their morphologies and structures are characterized by X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy, and thermogravimetric analysis. Their electrochemical properties are investigated by galvanostatic charge–discharge test. Li4Ti5O12 particles in Li4Ti5O12–KB and Li4Ti5O12–KB–MWCNT composite have a diameter of ca. 40–60 nm. The discharge specific capacity is 157 (0.1 C), 110 (20 C) and 93 (30 C) mAh g− 1 for Li4Ti5O12–KB composite, and 157 (0.1 C), 133 (20 C) and 105 (30 C) mAh g− 1 for Li4Ti5O12–KB–MWCNT composite. After 100 cycles at 5 C, the discharge capacity retention of Li4Ti5O12–KB and Li4Ti5O12–KB–MWCNTs is 94% and 96%, respectively. Li4Ti5O12 shows asymmetric behavior between charge and discharge. The excellent high rate performance of Li4Ti5O12–KB and Li4Ti5O12–KB–MWCNT composites can be attributed to the reduction of Li4Ti5O12 particle size and the improvement of electronic conductivity due to the uniform distribution of Li4Ti5O12 particles within the carbon matrix conductive network.

► High rate performance of Li4Ti5O12–KB and Li4Ti5O12–KB–MWCNTs are prepared. ► KB prohibits the growth of Li4Ti5O12 particles. ► MWCNTs combine with KB to form a three-dimensional conductive network. ► The asymmetric behavior between charge and discharge of Li4Ti5O12 exists.