Public Research Seminar by Sustainable Energy and Environment Thrust, HKUST(GZ) - Building Robust Electrode/Electrolyte Interfaces for Rechargeable Batteries

Electrode/electrolyte interfaces, including solid electrolyte interphase (SEI) and cathode electrolyte interphase (CEI), play vital roles in determining the kinetics and stability of rechargeable batteries. In this talk, I will discuss our results on i) Improving the mechanical stability of SEI. Extensive studies have been put on fabricating nanostructured electrodes to alleviate the volume change during charge/discharge, but accompanied by a low volumetric energy density. We turn to building an ultrathin SEI through ether-based electrolytes. The unique SEIs exhibit superior elasticity and render anomalous stability against the large volume change of the anodes. We propose the maximum elastic deformation energy to predict SEI’s mechanical stability, facilitating the rational interface design. ii) Elevating oxidation stability at the cathode. We extend the alkyl chains of traditional ethers to build stable CEI for application in high-voltage cathodes. This effectively reduces the catalytic reactivity of the cathode towards the electrolyte at high voltages, which suppresses the oxidation decomposition of the electrolyte, microstructural defects and rock-salt phase formation in the cathode, and gas release issues. iii) Boosting the interfacial kinetics. We demonstrate the paradigm shift in interface design when shifting from mono- to di-valent batteries, such as Ca-ion batteries. The sluggish kinetics at the electrode/electrolyte interfaces in divalent batteries could be resolved through electrolyte formulation and artificial interface design.