Education: Master's degree

Degree: Master

Status: Graduation

Thesis title: Preparation and electrochemical properties of iron-doped lithium phosphorus oxynitride solid-state electrolyte films

Research Interests: Solid-state electrolytes for lithium-ion batteries

Graduate School: International Graduate School of Tsinghua University Shenzhen

Introduction: The LiPON films were modified with Fe-doped (Fe-LiPON) by RF magnetron sputtering to achieve efficient ion transport, and the Fe doping concentration in the LiPON films was regulated by optimizing the process parameters and changing the target composition. Electrochemical performance tests show that the room temperature ionic conductivity of Fe-LiPON is as high as 1.08×10-5 S/cm, which is one order of magnitude higher than LiPON; the ion mobility number reaches 0.974 and the ion activation energy is only 0.42 eV, which has excellent ion transport kinetic properties. By XPS, SPM, and DFT analysis, the excellent ion conductivity of Fe-LiPON films comes from three aspects: first, the Fe multivalence property determines that it can form various types of Fe-N bridge bonds, connecting more adjacent PO3N4-tetrahedra to form ion transport channels and enhancing the network-forming body effect; second, the high electronegativity Fe triggers the Fe-LiPON local structure electron density field redistribution, reducing the PO3N4-tetrahedra and Li+ electrostatic force; third Fe doping increases the LiPON film work function to 3.90 eV and reduces the interface equilibrium potential difference to 0.78 V, promoting the dynamic diffusion of Li+ in the depletion layer.

Entrance date: 2018-09-01

Graduation date: 2021-06-30

Email: zhou-sy21@mails.tsinghua.edu.cn