锂离子电池微米级三维多孔硅负极材料合成及性能研究

Synthesis and Performance Research of Micron-Scale Three-Dimensional Porous Silicon Anode Material for Lithium-Ion Batteries

摘要:

三维硅已被证明为极具前景的锂离子电池负极材料，然而现有的三维硅负极在循环性能和初始库伦效率等方面存在挑战。采用盐酸刻蚀、镁热还原和表面组装的策略，从天然蒙脱矿土直接制备出微米级的三维多孔硅/二氧化钛（3D pSi@TiO₂）复合材料。结果表明：复合材料具有的三维多孔结构能够提供足够的空隙，缓解了脱-嵌锂过程中发生的体积膨胀，缩短了电子传输和锂离子扩散的路径，有利于锂离子的快速嵌入和脱出并减少极化；与二氧化钛的有效复合，进一步提高了复合材料的导电率及结构的稳定性；3D pSi@TiO₂负极在0.5A?g^-1电流密度下循环200次后，可逆容量高达1 261.19 mAh?g^-1及90.79%的优异容量保持率，同时初始库伦效率可达到80.6%。

Abstract:

Three-dimensional silicon has been proven to be a promising anode material for lithium-ion batteries. However， the existing three-dimensional silicon anodes have challenges in terms of cycling performance and initial coulombic efficiency. In this paper， micron-scale three-dimensional porous silicon/titanium dioxide （3D pSi@TiO₂） composites were directly prepared from natural montmorillonite via the strategy of hydrochloric acid etching， magnesium thermal reduction， and surface assembly. The results show that the 3D porous structure could provide enough voids to alleviate the volume expansion during the de-intercalation process and shorten the path of electron transport and lithium ion diffusion， which was conducive to the rapid intercalation and extraction of lithium ions and reduce polarization. The effective combination with the titanium dioxide further improved the conductivity and structural stability. The 3D pSi@TiO₂ anode revealed a high reversible capacity of 1 261.19 mAh?g^-1 after 200 cycles at 0.5 A?g^-1 current density， an excellent capacity retention rate of 90.79%， and an initial coulomb efficiency of 80.6%.