Ionic and mixed-Conductor polymers for all-solid-state batteries: towards Efficiency, Sustainability And Recyclability

• Applicant: Professor Dr. André Gröschel
• Subject Area: Polymer Materials
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 568901658

As the demand for high-performance batteries with increased power and energy density, but also more efficiency and sustainability, continues to rise, it becomes more and more clear that Li-ion batteries (LIBs) alone will not be able to satisfy our energy storage need in the near future. Thus, extensive research is currently invested to explore high-capacity and high-voltage active materials (Mn-based oxides such as spinels), advanced electrolytes, as well as novel battery technologies such as Na-ion batteries and all solid-state batteries. The objective of the CESAR project is to tackle the challenge of succeeding in the transition from liquid LIBs to all solid-state Lithium metal batteries (ASSBs). The project aims at preparing high-performance composite positive electrodes and solid electrolytes for ASSBs, considered as the next generation of safe and high-energy density storage systems (more than 450 Wh/kg expected vs. 300 Wh/kg today). To achieve this goal, we will consider ASSBs with (i) a mixed ionic-electronic polymer conductor as binder and electronic conductive additive for positive electrode (catholyte, i.e. intimate mixture of active positive electrode material and solid electrolyte at the particle level) and (ii) a 3D inorganic-polymer composite as electrolyte. We will develop innovative positive electrodes (catholytes) with the goal to maximize the electronic and ionic transport within the bulk of thick electrodes. For that. particles of the active material must be embedded and/or functionalized within an interconnected electronic and ionic conductive network, while mitigating irreversible reactivity and mechanical stress at the solid-solid interface between the catholyte and the electrolyte membrane. The design of 3D inorganic-polymer composite electrolytes will be the second focal point. Solid electrolytes will include Li-containing sulfides, and ‘dry’ polymer electrolytes will include modified phosphazene electrolytes. Solid polymer electrolytes (SPEs) are lightweight and can be easily prepared as thin films thanks to their good viscoelastic properties. But so far, they still suffer from a lower ionic conductivity at room temperature compared to their inorganic counterparts. To circumvent these limitations, we will focus our efforts on the preparation of composite polymer electrolytes (CPEs), where the ISE is located within the 3D structured pores of the SPEs. The development of SPEs with enhanced conduction properties will induce synergistic effects in these CPEs thanks to appropriate spatial organization, surface chemistry, and size effects. Solid-state electrolyte candidates will have to combine a high Li+ ionic conductivity at room-temperature and below, a low overall density, chemical compatibility with electrode materials, large electrochemical stability window, cost-effective synthesis, and easy integration in the battery manufacturing process.

• DFG Programme: Research Grants
• International Connection: France
• Cooperation Partners: Dr. Eric Cloutet; Professorin Dr. Laurence Croguennec