Development of an All-Solid State Li-Ion System

Li-ion batteries are considered as the most suitable electrochemical energy storage systems for a wide range of applications including automotive applications in order to contribute to the reduction of CO₂ emissions responsible for climate change.<br/>In recent years, the majority of the works on batteries has consisted in developing solid electrolytes with the goal to improve their safety and the possibility of using a negative electrode based on metallic lithium which will ultimately make it possible to achieve high energy densities.<br/>CEA-Liten and Saft have jointly developed a solid-state polymer electrolyte system. The polymer PTMC (Poly trimethylene carbonate) has been selected for its high transport number, over 0.7, and its stability with respect to lithium both at high potential and at low potential despite its modest conductivity.<br/>The Solid Polymer Electrolytes (SPE) realized is a crosslinked membrane based on PTMC, with good mechanical properties that allow an easy handling and integration into a complete system (Fig 1).<br/>The electrodes containing PTMC and NMC622, Graphite or SiOx as active material were manufactured with a surface capacities around 1mAh/cm². Their mechanical properties are similar to conventional Li-ion electrodes.<br/>Solid-state prototypes with a capacity around ten milliampere-hours have been assembled with these components. The performances of the all-solid prototypes containing PTMC are encouraging. Indeed, they operate correctly at a C/20 rate at 80°C but also at room temperature with the addition of plasticizers.