Chen Chunhui, Agrawal Richa, Wang Chunlei
Department of Mechanical and Materials Engineering, Florida International University, Miami, FL 33174, USA.
Nanomaterials (Basel). 2015 Aug 28;5(3):1469-1480. doi: 10.3390/nano5031469.
Improving the energy capacity of spinel Li₄Ti₅O (LTO) is very important to utilize it as a high-performance Li-ion battery (LIB) electrode. In this work, LTO/Si composites with different weight ratios were prepared and tested as anodes. The anodic and cathodic peaks from both LTO and silicon were apparent in the composites, indicating that each component was active upon Li⁺ insertion and extraction. The composites with higher Si contents (LTO:Si = 35:35) exhibited superior specific capacity (1004 mAh·g) at lower current densities (0.22 A·g) but the capacity deteriorated at higher current densities. On the other hand, the electrodes with moderate Si contents (LTO:Si = 50:20) were able to deliver stable capacity (100 mAh·g) with good cycling performance, even at a very high current density of 7 A·g. The improvement in specific capacity and rate performance was a direct result of the synergy between LTO and Si; the former can alleviate the stresses from volumetric changes in Si upon cycling, while Si can add to the capacity of the composite. Therefore, it has been demonstrated that the addition of Si and concentration optimization is an easy yet an effective way to produce high performance LTO-based electrodes for lithium-ion batteries.
提高尖晶石Li₄Ti₅O（LTO）的能量容量对于将其用作高性能锂离子电池（LIB）电极非常重要。在这项工作中，制备了不同重量比的LTO/Si复合材料并将其作为阳极进行测试。复合材料中LTO和硅的阳极和阴极峰都很明显，这表明每个组分在Li⁺嵌入和脱出时都具有活性。具有较高Si含量（LTO:Si = 35:35）的复合材料在较低电流密度（0.22 A·g）下表现出优异的比容量（1004 mAh·g），但在较高电流密度下容量会下降。另一方面，具有中等Si含量（LTO:Si = 50:20）的电极即使在7 A·g的非常高电流密度下也能够提供稳定的容量（100 mAh·g）并具有良好的循环性能。比容量和倍率性能的提高是LTO和Si之间协同作用的直接结果；前者可以减轻循环时Si体积变化产生的应力，而Si可以增加复合材料的容量。因此，已经证明添加Si和浓度优化是生产用于锂离子电池的高性能LTO基电极的一种简单而有效的方法。
