Molten Salt Synthesis of Transition Metal Oxides Modified Li4Ti5O12 As Anode Material of Li-Ion Battery

Abstract

In order to meet the requirement for the rapid development of electric vehicles (EVs) and hybrid electric vehicles (HEVs), lithium-ion batteries (LIBs) with high safety, high stability and high energy are urgently needed. Spinel-type Li4Ti5O12 (LTO) has become the most promising anode material of the LIBs used in EVs and HEVs as its’ zero variation. However, LTO intrinsically insulative character, and large polarization at high rates restrict its high energy and power density. Our study focuses on increasing the specific surface area and electron conduction through thimbleful transition metal oxides (Fe2O3, Fe3O4, Co3O4) modifying LTO bymolten salts synthesis method. Transition metal oxides not only decrease greatly on particle size, but also enhance the electrochemical performances of LTO and the reaction mechanism is investigated. Transition metal atoms as the interstitial and substitutional atoms homogenously distributes in the crystal lattice of LTO. The optimal modified LTO exhibits a excellent first discharge capacity of 269.3 mAh g-1 at the 0.1 C and 201.3 mAh g-1 at 1 C; good high rate capability (123.4 mAh g-1 at 12 C). Doping increases nucleation sites during LTO formation in molten salts which reduces the particle size of LTO. Substituted atoms expand the paths for Li+ de/ intercalation and cause O32e or Li8a,16d vacant sites which improves the electronic conductivity of LTO. These findings indicate thimbleful metal oxides doping as an effective method to improve LTO performance by use of molten salt method which can use on the industrial production. KEYWORDS: molten salt, transition metal oxides, Li4Ti5O12, anode material, lithium-ion battery