Advanced BaLi₂Ti₆O₁₄ Anode Fabricated via Lithium Site Substitution by Magnesium

Advanced Na- and Mg-doped BaLi₂Ti₆O₁₄ anodes in the form of BaLi_1.9M_0.1Ti₆O₁₄ (M = Na, Mg) are successfully fabricated and evaluated as lithium storage materials for rechargeable lithium-ion batteries. The effects of Na- and Mg-dopings on the crystal structure, surface morphology and electrochemical behavior are investigated for BaLi₂Ti₆O₁₄. The results show that both Na and Mg elements are successfully introduced into the Li site, and they do not alter the basic structure of BaLi₂Ti₆O₁₄. The resulting BaLi_1.9M_0.1Ti₆O₁₄ (M = Na, Mg) exhibit significant improvements on the electrochemical performance in terms of the rate capability and cycle performance. Especially for BaLi_1.9Mg_0.1Ti₆O₁₄, it can deliver an initial charge capacity of 111.7 mAh g^–1 at 5C. After 200 cycles, it still can maintain a reversible capacity of 90.1 mAh g^–1 with the capacity retention of 80.7%. The enhanced electrochemical properties can be attributed to the reduced particle size, decreased charge transfer resistance and enhanced ionic/electronic conductivity induced by Mg doping. Besides, in situ X-ray diffraction also reveals that BaLi_1.9Mg_0.1Ti₆O₁₄ has high structural stability and reversibility during charge/discharge process