Carbon/Li4Ti5O12Composite Spheres Prepared Using Chinese Yam as Carbon Source with Ultrahigh Capacity as Anode Materials for Lithium Ion Batteries

Spinel structured Li4Ti5O12(LTO) spheres modified with carbon (Carbon/LTO composites) using Chinese yam (CY) as carbon source have been obtained by a hydrothermal method combining with a calcining at 700 °C in N2atmosphere. The influences of the additions of CY on the morphology, structure, carbon content and also the electrochemical properties of the resulted carbon/LTO composite spheres have been investigated in details. SEM and TEM investigations show that all the composites possess spherical morphology and consist of nanosized Li4Ti5O12crystals modified with carbon. With the increase of CY additions, the size of Li4Ti5O12primary crystals decrease gradually, and reach to a turn over point and then the crystal size turn to large ones when the CY content increased further. It has been demonstrated that carbon modification of Li4Ti5O12with Chinese yam as carbon source could efficiently improve the electrochemical performance of Li4Ti5O12. One of the composite sample named as C/LTO‐10 shows an ultrahigh initial specific capacity of about 211.9 mAh ⋅ g−1at a current density of 1 C. It shows excellent cycle performance and maintains a specific capacity of 184.5 mAh ⋅ g−1even after 300 cycles. A specific capacity of 123.5 mAh ⋅ g−1still could be delivered at a high current density of 30 C, exhibiting also superior rate capability. Composites of Li4Ti5O12modified with N doped carbon have been prepared with Chinese yam as carbon precursor by using a hydrothermal method and followed by a calcination process at 700 °C. The composites show an ultrahigh initial specific capacity of about 211.9 mAh.g−1at a current density of 1 C. Even after 300 cycles a specific capacity of 184.5 mAh ⋅ g−1still could be maintained. A specific capacity of 123.5 mAh ⋅ g−1were delivered at a high current density of 30 C, exhibiting also superior rate capability.