Towards advanced lithium metal solid-state batteries: Durable and safe multilayer pouch cell enabled by a nanocomposite solid electrolyte

Lithium metal solid-state batteries (SSBs) are expected to outperform the current lithium-ion battery technology, limited by the performance, energy density, and safety issues. One of the most promising classes of solid electrolytes for SSBs are polymer-inorganic composites. However, incompatibility between inorganic and polymer phases may affect the solid electrolyte properties and, therefore, the SSB performance. Therefore, in this study, novel nanocomposite solid polymer electrolytes (nCSPE), containing inert alumina nanoparticles with specially customized interface, are successfully synthesized. Thermal, mechanical, electrical and electrochemical properties of the prepared nCSPEs are evaluated to select the most promising solid electrolyte formulation for its further scale-up. Afterwards, multilayer solid state pouch-type cells with a nominal capacity of ca. 0.5 Ah are successfully prepared, using the developed nCSPE, current-collector-free thin Li metal anode, and double-sided composite LiFePO4 cathode. “Li/nCSPE/LiFePO4” prototype pouch cells are cycled at 60 °C, exhibiting long cycle life with more than 2000 cycles with a high coulombic efficiency, and enhanced safety in the fully charged state. This research could contribute to promising advances on the development of new generation of high performant and safe Li metal SSBs.