Improved Li-Storage Performance of Li4Ti5O12 Coated with C?N Compounds Derived from Pyrolysis of Urea through a Low-Temperature Approach

A uniform and thin amorphous layer of a C?N compound was coated on porous Li4Ti5O12 by pyrolysis of urea on its surface at a rather low temperature of 400 degrees C in an Ar atmosphere. Such a CN coating layer greatly improved the electrochemical performance of Li4Ti5O12. After coating, Li4Ti5O12 showed good rate and excellent cycling performance. Reversible capacities for the coated sample of 134 and 105 mAhg-1 were obtained at current rates of 5C and 10C, respectively, in the voltage range of 12.2 V, which is approximately two and five times higher than those of pristine Li4Ti5O12 at the same current rates. Excellent capacity retention of 95.8?% was achieved for the coated sample after 2000 cycles in a half cell at a 2C rate.