Effect of Sodium-Site Doping on Enhancing the Lithium Storage Performance of Sodium Lithium Titanate

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• 作者：Pengfei Wang ; Shangshu Qian ; Ting-Feng Yi ; Haoxiang Yu ; Lei Yan ; Peng Li ; Xiaoting Lin ; Miao Shui ; Jie Shu
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2016
• 出版时间：April 27, 2016
• 年：2016
• 卷：8
• 期：16
• 页码：10302-10314
• 全文大小：1264K
• 年卷期：0
• ISSN：1944-8252

文摘

Via Li⁺, Cu²⁺, Y³⁺, Ce⁴⁺, and Nb⁵⁺ dopings, a series of Na-site-substituted Na_1.9M_0.1Li₂Ti₆O₁₄ are prepared and evaluated as lithium storage host materials. Structural and electrochemical analyses suggest that Na-site substitution by high-valent metal ions can effectively enhance the ionic and electronic conductivities of Na₂Li₂Ti₆O₁₄. As a result, Cu²⁺-, Y³⁺-, Ce⁴⁺-, and Nb⁵⁺-doped samples reveal better electrochemical performance than bare Na₂Li₂Ti₆O₁₄, especially for Na_1.9Nb_0.1Li₂Ti₆O₁₄, which can deliver the highest reversible charge capacity of 259.4 mAh g^–1 at 100 mA g^–1 among all samples. Even when cycled at higher rates, Na_1.9Nb_0.1Li₂Ti₆O₁₄ still can maintain excellent lithium storage capability with the reversible charge capacities of 242.9 mAh g^–1 at 700 mA g^–1, 216.4 mAh g^–1 at 900 mA g^–1, and 190.5 mAh g^–1 at 1100 mA g^–1. In addition, ex situ and in situ observations demonstrate that the zero-strain characteristic should also be responsible for the outstanding lithium storage capability of Na_1.9Nb_0.1Li₂Ti₆O₁₄. All of this evidence indicates that Na_1.9Nb_0.1Li₂Ti₆O₁₄ is a high-performance anode material for rechargeable lithium ion batteries.