Synthesis and evaluation of novel hybrid solid electrolytes for lithium metal batteries
(2023)
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- Authors
- Supervisors
- Gohy, Jean-François
- Abstract
- The electrification of the automotive industry presents two major challenges: ensuring safer battery packs and increasing energy density for extended range autonomy. These challenges are closely tied to the current technology of lithium-ion batteries, which utilize a flammable liquid electrolyte and already offer nearly maximum energy density in their associated electrodes. To address these issues, solid-state batteries with nonflammable solid electrolytes and high energy density electrodes have emerged as promising candidates. In this thesis, we have demonstrated the feasibility of utilizing a novel hybrid solid electrolyte in a full-cell battery configuration. This electrolyte is composed of a ternary polymer matrix, comprising a fire-retardant phosphonate, an ionic conductive cyclocarbonate, and a flexible and ionic conductive boronate. The electrochemical stability (>4.2 V vs Li+/Li) and ionic conductivity (~10-5 S.cm-1 at 20°C) achieved were comparable to state-of-the-art polymer electrolytes. Furthermore, we found that copolymers, rather than homopolymer blends, exhibited higher ionic conductivity at room temperature while maintaining similar conductivity at 60°C. However, it should be noted that homopolymer blends required preheating to achieve microscopic homogeneity. Moreover, we enhanced this system by incorporating 20%wt inorganic particles, namely LLZWO garnet or alumina, using a solvent-free extrusion technique. This resulted in the production of hybrid flexible self-standing films, wherein the inorganic particles were uniformly dispersed within a homopolymer blend matrix. These films exhibited an ionic conductivity of 2.44 x 10-4 S.cm-1 and a transference number of 0.86 at 60°C. Additionally, the hybrid extruded films displayed fire-retardant and self-extinguishing capabilities. Furthermore, this system demonstrated good cycling stability, achieving a capacity retention of 93% (115 mAh.g-1) after 200 cycles at 60°C when combined with a catholyte comprising NMC111, our ternary polymer matrix, and conductive carbon. Overall, the findings of this research highlight the potential of a hybrid solid electrolyte system for solid-state batteries, offering improved safety, enhanced electrochemical performance, and fire-retardant properties. These advancements contribute to the development of next-generation battery technologies for the electrification of the automotive industry.
- Affiliations
Citations
Notredame, B. (2023). Synthesis and evaluation of novel hybrid solid electrolytes for lithium metal batteries. https://hdl.handle.net/2078.5/233723