Molten Salt Synthesis of Transition Metal Oxides doped Li4Ti5O12 as Anode Material of Li-Ion Battery

Abstract

Co3O4 doped Li4Ti5O12 compounds with protuberant nanoparticles are synthesized by molten salts method. Co3O4 doping greatly decreases particle size of Li4Ti5O12. Combining with the result of Fe2O3 doped Li4Ti5O12 and as interstitial and substitutional atoms, transition metal atoms homogenously distribute in the crystal lattice of Li4Ti5O12 and do not change the cubic spinel structure of Li4Ti5O12. As the substitutional atoms, the mixed valence of Co3+ and Co2+ co-exists in Li4Ti5O12 causing O32e or Li8a,16d vacant sites thereby improving the electronic conductivity of Li4Ti5O12. The doped Li4Ti5O12 exhibits a large first discharge capacity (173.5 mAh g-1) at 0.2 C rate, 144.8 mAh g-1 at 1 C rate with the capacity loss of 8.8% after 100 charge/discharge cycles and 106 mAh g-1 at 10 C. EIS analysis indicates the doped Li4Ti5O12 electrode exhibits lower charge transfer resistance and lithium ions diffusion resistance, as optimized amounts of Co3O4 produces appropriate lattice distortion and interstitial atoms in Li4Ti5O12.