AVS 66th International Symposium & Exhibition
    Thin Films Division Thursday Sessions
       Session TF+SS-ThA

Invited Paper TF+SS-ThA1
Tailoring Electrode-electrolyte Interfaces in Lithium-ion Batteries using Molecularly Engineered Functional Polymers

Thursday, October 24, 2019, 2:20 pm, Room A122-123

Session: Metal Halide Perovskites, Other Organic/Inorganic Hybrid Thin Films
Presenter: Laisuo Su, Carnegie Mellon University
Authors: L Su, Carnegie Mellon University
J. Weaver, National Institute of Standards and Technology (NIST)
M. Groenenboom, National Institute of Sandards and Technology (NIST)
B.R. Jayan, Carnegie Mellon University
Correspondent: Click to Email
The performance and stability of lithium ion batteries (LIBs) depend on charge transfer and reactions at electrode-electrolyte interfaces (EEI), making interfaces design a key issue. Here we molecularly engineer this interface using conformal, functional polymer nanolayers via a novel vapor-based deposition technique. We demonstrate that poly(3,4-ethylenedioxythiophene) (PEDOT) nanolayer doubles the capacities of LiCoO2 at high rates and extends its 4.5 V cycling life by 260%. The improved rate performance is enabled by high diffusion coefficient of Li+ in PEDOT measured from neutron depth profiling. Such behavior is further understood by density functional theory (DFT) simulation. The extended cycling stability comes from strong interactions between PEDOT and Co atoms, as suggested from X-ray photoelectron spectroscopy and DFT simulations. Additionally, in-situ synchrotron X-ray diffraction reveals that PEDOT uniformizes current distribution and improves LiCoO2 structural stability during cycling tests. This work adds understanding and provides guidelines for designing the EEI for advanced LIBs.