Liu Yuxuan, Hu Renzong, Zhang Dechao, Liu Jiangwen, Liu Fang, Cui Jie, Lin Zuopeng, Wu Jinsong, Zhu Min
Guangdong Provincial Key Laboratory of Advanced Energy Storage Materials, School of Materials Science and Engineering, South China University of Technology, Guangzhou, 510640, China.
Nanostructure Research Center, Wuhan University of Technology, Wuhan, 430070, China.
Adv Mater. 2021 Mar;33(11):e2004711. doi: 10.1002/adma.202004711. Epub 2021 Jan 29.
To achieve high ionic conductivity for solid electrolyte, an artificial Li-rich interface layer of about 60 nm thick has been constructed in polymer-based poly(ethylene oxide)-lithium bis(trifluoromethanesulfonyl)imide composite solid electrolyte (briefly noted as PEO ) by adding Li-based alloys. As revealed by high-resolution transmission electron microscopy and electron energy loss spectroscopy, an artificial interface layer of amorphous feature is created around the Li-based alloy particles with the gradient distribution of Li across it. Electrochemical analysis and theoretical modeling demonstrate that the interface layer provides fast ion transport path and plays a key role in achieving high and stable ionic conductivity for PEO -Li Si composite solid electrolyte. The PEO -5%Li Si composite electrolyte exhibits an ionic conductivity of 3.9 × 10 S cm at 30 °C and 5.6 × 10 S cm at 45 °C. The LiFePO | PEO -5%Li Si | Li all-solid-state batteries could maintain a stable capacity of 129.2 mA h g at 0.2 C and 30 °C after 100 cycles, and 111.3 mA h g after 200 cycles at 0.5 C and 45 °C, demonstrating excellent cycling stability and high-rate capability.
为了实现固体电解质的高离子电导率，通过添加锂基合金，在聚合物基聚环氧乙烷-双（三氟甲烷磺酰）亚胺锂复合固体电解质（简称为PEO）中构建了一个厚度约为60纳米的富锂人工界面层。高分辨率透射电子显微镜和电子能量损失谱显示，在锂基合金颗粒周围形成了一个具有非晶态特征的人工界面层，锂在其中呈梯度分布。电化学分析和理论建模表明，该界面层提供了快速离子传输路径，对实现PEO-Li-Si复合固体电解质的高且稳定的离子电导率起着关键作用。PEO-5%Li-Si复合电解质在30℃时的离子电导率为3.9×10⁻⁴ S·cm⁻¹，在45℃时为5.6×10⁻⁴ S·cm⁻¹。LiFePO₄|PEO-5%Li-Si|Li全固态电池在0.2 C和30℃下循环100次后，可保持129.2 mA·h·g⁻¹的稳定容量，在0.5 C和45℃下循环200次后为111.3 mA·h·g⁻¹，表现出优异的循环稳定性和高倍率性能。
