Molten Salt Synthesis of Transition Metal Oxides Doped Li_4Ti_5O_(12) as Anode Material of Li-ion Battery

摘要

Co_3O_4 doped Li_4Ti_5O_(12) compounds with protuberant nanoparticles are synthesized by molten salts method. Co_3O_4 doping greatly decreases particle size of Li_4Ti_5O_(12). Combining with the result of Fe_2O_3 doped Li_4Ti_5O_(12) and as interstitial and substitutional atoms, transition metal atoms homogenously distribute in the crystal lattice of Li_4Ti_5O_(12) and do not change the cubic spinel structure of Li_4Ti_5O_(12). As the substitutional atoms, the mixed valence of Co~(3+) and Co~(2+) co-exists in Li_4Ti_5O_(12) causing O~(32e) or Li~(8a,16d) vacant sites thereby improving the electronic conductivity of Li_4Ti_5O_(12). The doped Li_4Ti_5O_(12) 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 Li_4Ti_5O_(12) electrode exhibits lower charge transfer resistance and lithium ions diffusion resistance, as optimized amounts of Co_3O_4 produces appropriate lattice distortion and interstitial atoms in Li_4Ti_5O_(12).