Constructing Li-Rich Artificial SEI Layer in Alloy-Polymer Composite Electrolyte to Achieve High Ionic Conductivity for All Solid-State Lithium Metal Batteries

作者：Liu, Yuxuan; Hu, Renzong^*; Zhang, Dechao; Liu, Jiangwen; Liu, Fang; Cui, Jie; Lin, Zuopeng; Wu, Jinsong; Zhu, Min^*

来源：Advanced Materials, 2021, 33(11): 2004711.

DOI：10.1002/adma.202004711

• all solid-state lithium ion battery
• artificial solid electrolyte interface
• composite polymer electrolytes
• lithium metal batteries
• lithium-silicon alloys
• poly(ethylene oxide)

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 PEOm) 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 PEOm-Li21Si5 composite solid electrolyte. The PEOm-5%Li21Si5 composite electrolyte exhibits an ionic conductivity of 3.9 x 10(-5) S cm(-1) at 30 degrees C and 5.6 x 10(-4) S cm(-1) at 45 degrees C. The LiFePO4 | PEOm-5%Li21Si5 | Li all-solid-state batteries could maintain a stable capacity of 129.2 mA h g(-1) at 0.2 C and 30 degrees C after 100 cycles, and 111.3 mA h g(-1) after 200 cycles at 0.5 C and 45 degrees C, demonstrating excellent cycling stability and high-rate capability.

• 单位
  武汉理工大学; test; TEST