Carbon Paper-Based C:TiO_x Anode Material for Rapid Charge Lib Application

As energy issues go viral, the use of lithium-ion batteries is thought to be a practical solution for electric vehicles due to its high specific capacity. However, the poor high-rate capability of the commonly used carbon anodes limits their application. In contrast, we use TiO2 as an anode to mitigate this issue. In the previous work, a non-stoichiometric TiOx nanopowder was fabricated under the influence of a reduced atmosphere to further enhance its capacity. However, due to a lack of interfacial compatibility, the high electrochemical impedance deteriorates the capacity after the first cycle. Thus, in this work, we use the methane treatment to mitigate the issue to enhance the initial coulombic efficiency from 60% to below 30%. The theoretical capacity of TiO2, TiOx, and C:TiOx are all 335 mAh/g. However, with the surface modification, the experimental capacity can improve. Besides, to avoid absorption during X-ray based analyses, we use a carbon paper substrate to mitigate this issue instead of the copper substrate. Herein, we perform an easy and effective method to improve both the ICE and the capacity at the same time by the reduction process followed by carbon doping as the artificial SEI. The performance of the battery shows that the electrode has a great initial capacity of 1013 mAh/g with 70% ICE, and holds a retention of 700 mAh/g at a rate of 67 mA/g (0.2C) with ~100% CE after formatting. While for the battery without coating, the initial capacity is 752 mAh/g with a 70% ICE and a CE of ~100%, the retention capacity is, however, only 450 mAh/g at the same rate and decreases at a visible speed. Based on the above ex-situ results, the mechanism during charge and discharge revealed by in-situ measurements is due. We will further use the synchrotron radiation and the in-operando Raman to clarify the phase transformation behavior, especially at a rapid charging rate.