Constructing Li-Rich Artificial SEI Layer in Alloy-Polymer Composite Electrolyte to Achieve High Ionic Conductivity for All-Solid-State Lithium Metal Batteries.
basic_science · Level V
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- Record sourced from PubMed, PMID 33511690.
- Also identified by DOI 10.1002/adma.202004711.
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Abstract
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<sub>m</sub> ) 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<sub>m</sub> -Li<sub>21</sub> Si<sub>5</sub> composite solid electrolyte. The PEO<sub>m</sub> -5%Li<sub>21</sub> Si<sub>5</sub> composite electrolyte exhibits an ionic conductivity of 3.9 × 10<sup>-5</sup> S cm<sup>-1</sup> at 30 °C and 5.6 × 10<sup>-4</sup> S cm<sup>-1</sup> at 45 °C. The LiFePO<sub>4</sub> | PEO<sub>m</sub> -5%Li<sub>21</sub> Si<sub>5</sub> | Li all-solid-state batteries could maintain a stable capacity of 129.2 mA h g<sup>-1</sup> at 0.2 C and 30 °C after 100 cycles, and 111.3 mA h g<sup>-1</sup> after 200 cycles at 0.5 C and 45 °C, demonstrating excellent cycling stability and high-rate capability.