基于碳纳米管宏观膜集流体的高比容量及高电化学稳定性钛酸锂负极

High Specific Capacity and Electrochemical Stability Lithium Titanate Negative Electrode Based on Carbon Nanotubes Macro Film Current Collector

通过预先将钛酸锂(Li4Ti5O_(12),LTO)材料组装的电池进行预充电脱锂(活化)的方式改变其结构,增强嵌锂能力,制备出高比容量LTO;随后以碳纳米管宏观膜(CMF)为集流体,替代金属箔集流体改善活性物质与集流体的结合界面,提高其电化学稳定性,最终得到具有高比容量及高稳定性的LTO电极。采用X射线衍射(XRD)、扫描电子显微镜(SEM)和电化学测试等对LTO材料进行表征。结果表明:经过预脱锂活化后的LTO可容纳锂离子的空位增加,晶面间距明显增大,经测试其在1 C倍率能发挥192.7 m Ah·g^(-1)的比容量,比正常的LTO材料提高约30 m Ah·g^(-1);引入的CMF集流体能增强与活性材料的结合力,减小其在大电流下产生的接触阻抗,使其在5 C倍率下仍具有150 m Ah·g^(-1)的比容量,表现出优异的倍率性能。

Changing the structure of lithium titanate(Li4Ti5O_(12),Abbre.LTO)material by delithiation(activation)in advance,to increase the internal lithium ion vacancy and enhance the lithium intercalation ability,a high specific capacity LTO was prepared.CMF(carbon nanotubes macro film)was introduced as a current collector instead of metal foil to improve its electrochemical stability.Finally,a LTO electrode having high specific capacity and high stability was obtained.Characterization was executed by X-ray diffraction(XRD),scanning electron microscopy(SEM)and electrochemical testing.The results show that the activated LTO can achieve a specific capacity of 192.7 mAh·g^(-1)at 1 C rate,which is about 30 mAh·g^(-1)higher than that of the normal LTO material.The introduced CMF current collector can enhance the binding force with the active material,and it still possesses a specific capacity of 150 mAh·g^(-1)at 5 C rate,exhibiting excellent rate performance.