Cycling of block copolymer composites with lithium-conducting ceramic nanoparticles

Vivaan Patel; Michael A Dato; Saheli Chakraborty; Xi Jiang; Min Chen; Matthew Moy; Xiaopeng Yu; Jacqueline A Maslyn; Linhua Hu; Jordi Cabana; Nitash P Balsara

doi:10.3389/fchem.2023.1199677

Cycling of block copolymer composites with lithium-conducting ceramic nanoparticles

Front Chem. 2023 Jun 2:11:1199677. doi: 10.3389/fchem.2023.1199677. eCollection 2023.

Authors

Vivaan Patel^{1

2}, Michael A Dato³, Saheli Chakraborty², Xi Jiang², Min Chen⁴, Matthew Moy¹, Xiaopeng Yu², Jacqueline A Maslyn¹, Linhua Hu³, Jordi Cabana³, Nitash P Balsara^{1

2

5}

Affiliations

¹ Department of Chemical and Biomolecular Engineering, University of California, Berkeley, Berkeley, CA, United States.
² Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, United States.
³ Department of Chemistry, University of Illinois at Chicago, Chicago, IL, United States.
⁴ Department of Materials Science and Engineering, University of California, Berkeley, Berkeley, CA, United States.
⁵ Energy Storage and Distributed Resources Division, Lawrence Berkeley National Laboratory, Berkeley, CA, United States.

Abstract

Solid polymer and perovskite-type ceramic electrolytes have both shown promise in advancing solid-state lithium metal batteries. Despite their favorable interfacial stability against lithium metal, polymer electrolytes face issues due to their low ionic conductivity and poor mechanical strength. Highly conductive and mechanically robust ceramics, on the other hand, cannot physically remain in contact with redox-active particles that expand and contract during charge-discharge cycles unless excessive pressures are used. To overcome the disadvantages of each material, polymer-ceramic composites can be formed; however, depletion interactions will always lead to aggregation of the ceramic particles if a homopolymer above its melting temperature is used. In this study, we incorporate Li_0.33La_0.56TiO₃ (LLTO) nanoparticles into a block copolymer, polystyrene-b-poly (ethylene oxide) (SEO), to develop a polymer-composite electrolyte (SEO-LLTO). TEMs of the same nanoparticles in polyethylene oxide (PEO) show highly aggregated particles whereas a significant fraction of the nanoparticles are dispersed within the PEO-rich lamellae of the SEO-LLTO electrolyte. We use synchrotron hard x-ray microtomography to study the cell failure and interfacial stability of SEO-LLTO in cycled lithium-lithium symmetric cells. Three-dimensional tomograms reveal the formation of large globular lithium structures in the vicinity of the LLTO aggregates. Encasing the SEO-LLTO between layers of SEO to form a "sandwich" electrolyte, we prevent direct contact of LLTO with lithium metal, which allows for the passage of seven-fold higher current densities without signatures of lithium deposition around LLTO. We posit that eliminating particle clustering and direct contact of LLTO and lithium metal through dry processing techniques is crucial to enabling composite electrolytes.

Keywords: LLTO; block copolymer electrolyte; cell cycling behavior; ceramic electrolyte; composite electrolyte; lithium metal anode; x-ray tomography.

Grants and funding

This work was supported by the Assistant Secretary for Energy Efficiency and Renewable Energy, Office of Vehicle Technologies, of the United States Department of Energy, under Contract DE-AC02-05CH11231 under the Battery Materials Research Program. Work at the University of Illinois at Chicago was partially supported by the National Science Foundation under Award CBET-2022723.