MSE PhD Final Defense: Anton Resing

MSE PhD Final Defense: Zhancheng Yao

TITLE: Architected Materials to Study and Mitigate Mass Transfer Limitations Pervasive in Electrochemical Energy Storage

ADVISOR: Joerg Werner ME, MSE, Chemistry

COMMITTEE: Sean Lubner ME, MSE; William Boley ME, MSE; Srikanth Gopalan ME, MSE; Chair: Chuanhua Duan ME, MSE

ABSTRACT: Electrochemical energy storage has achieved performance enhancements as fundamental hurdles have been met, even while the original planar structure and random arrangement of materials within battery electrodes have remained the same. Together, these two factors amplify mass-transfer constraints and limit the critical lithiation rates of energy-dense batteries. To alleviate societal demure towards the full adoption of electric vehicles and enable, for example, electric vertical take-off and landing aircraft, fast lithiation is a principal challenge that industry and academia must overcome. The proposed next step in battery evolution involves geometric changes to the electrode architecture in the form of low-tortuosity ion transport channels. This goal requires reimagined processing methods to move beyond planar electrodes with disorganized and heterogeneous porosity, to micro-architected electrodes with dual-scale aligned porosity. This thesis establishes and details one such innovative process, hybrid inorganic phase inversion (HIPI), a manufacturing method that is scalable, material-agnostic, and results in low-tortuosity free-standing architectures with tunable material-to-pore ratios. First, the thermodynamic and kinetic mechanisms related to the wide ranging tunability of HIPI-derived electrodes are illuminated. Next, by applying these fundamental insights into particle-polymer phase separation, architecture-performance relationships are investigated across a large library of tailored composite electrodes with systematic variations in primary channel and secondary interparticle porosity. The coupled effect of these two distinct scales of porosity on rate limitations are revealed and the results stress that an application-informed balance between channel and interparticle porosity is required. Lastly, this thesis explores single-material mixed ion- and electron-conducting HIPI-derived electrodes, whose fast charging is found to be enabled by nonequilibrium multi-phase lithiation. Overall, this thesis demonstrates that rational geometric changes to electrode architecture are a chemistry-agnostic approach to boost capacity and energy at high lithiation rates.