Improved Li-storage performance of Li4Ti5O12 coated with C-N compounds derived from pyrolysis of urea through a low-temperature approach

Abstract

A uniform and thin amorphous layer of a C-N compound was coated on porous Li(4)Ti(5)O(12) by pyrolysis of urea on its surface at a rather low temperature of 400 °C in an Ar atmosphere. Such a C-N coating layer greatly improved the electrochemical performance of Li(4)Ti(5)O(12). After coating, Li(4)Ti(5)O(12) showed good rate and excellent cycling performance. Reversible capacities for the coated sample of 134 and 105 mAh g(-1) were obtained at current rates of 5C and 10C, respectively, in the voltage range of 1-2.2 V, which is approximately two and five times higher than those of pristine Li(4)Ti(5)O(12) 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.