Cationic and Anionic Vacancy-Dependent Memory Effect in TiO2

Nickel–cadmium and nickel–metal hydride batteries exhibit voltage deviations due to usage history, and this process is referred to as the memory effect. Recently, it has been revealed that lithium-ion intercalation materials with a flat voltage plateau are also susceptible to a memory effect that complicates their state-of-charge estimation. The memory effect in TiO2 is known to be affected by particle size and Li-ion mobility. Here, we report that the type of vacancies in TiO2 is also critical to dictate the extent of the memory effect in TiO2.