Ammonia-Annealed TiO 2 as a Negative Electrode Material in Li-Ion Batteries: N Doping or Oxygen A

Improving the chemical dif- fusion of Li ions in anatase TiO2 is es- sential to enhance its rate capability as a negative electrode for Li-ion batter- ies. Ammonia annealing has been used to improve the rate capability of Li4Ti5O12. Similarly, ammonia anneal- ing improves the Li-ion storage per- formance of anatase TiO2 in terms of the stability upon cycling and the C- rate capability. In order to distinguish whether N doping or oxygen deficien- cies, both introduced upon ammonia annealing, are more relevant for the observed improvement, a systematic electrochemical study was performed. The results suggest that the creation of oxygen vacancies upon ammonia an- nealing is the main reason for the im- provement of the stability and C-rate capability.