非晶二氧化钛超薄纳米片用于稳定的高倍率锂储存

Amorphous TiO_(2)ultrathin nanosheet for stable high-rate lithium storage

嵌入型金属氧化物由于降低了低电压下锂沉积风险,作为负极材料在可充电锂离子电池中广泛使用。然而,这类电极材料较低的能量密度、功率密度及循环稳定性差限制了其快充的能力。我们设计合成了一种具备良好电化学循环稳定性的非晶二氧化钛纳米片,在500 mA·g^(-1)的电流密度下循环200圈后具有231 mA·h·g^(-1)的比容量,在6 A·g^(-1)的高电流密度下经过1000圈循环后保持了156.7 mA·h·g^(-1)的比容量。非晶二氧化钛纳米片高倍率性能的提升归因于开放的高度各向同性的结构特性,降低了离子迁移能垒,确保了离子可用性,降低了嵌入后材料的体积变化。本研究表明非晶化是一种有望开发具有高倍率性能的传统金属氧化物电极材料的策略。

The use of intercalation-type metal oxides as anode materials in rechargeable lithium-ion batteries is appealing due to their reduced risk of Li plating at low voltages.However,their implementation for fast-charging applications is limited by their lower energy and power density,as well as cycling instability.Herein,we present an amorphous TiO2 nanosheet that exhibits exceptional cycling stability with a high capacity of 231 mA·h·g^(−1)after 200 cycles at 500 mA·g^(−1)and 156.7 mA·h·g^(−1)after 1000 cycles at a high current density of 6 A·g^(−1).We attribute the enhanced rate performance to the amorphous nature with high isotropy,which facilitates low energy migration paths and ion availability and can accommodate large changes in volume.This work suggests that amorphization represents a promising strategy for developing unconventional metal oxide electrode materials with high-rate performance.