Insights in the interaction between cathode active materials and a new generation solid electrolyte

Abstract

The need for sustainable mobility leads to a growth of the market of electric cars. At this moment, lithium ion batteries are the most suitable technology due to their high gravimetric and volumetric energy density. In all roadmaps for battery development, solid state batteries are the next step after advanced Li-ion batteries. They offer the potential to significantly increase the energy density, combined with a higher safety due to the absence of a flammable liquid electrolyte. During the last years, research on solid state batteries has significantly increased, but still faces fundamental challenges, such as the development of a high-performance solid electrolyte, integration of the cathode active material with the solid electrolyte, and the integration of the Li metal anode which is needed to obtain the predefined energy densities. The goal of this study is to obtain insights in the interaction between LiNi1-x-yMnxCoyO2 active cathode materials and a new solid electrolyte. A polymer based eutectogel is used as the solid electrolyte. The eutectogel is a new class of solid composite electrolytes in which a deep eutectic solvent (MAc/LiTFSI) is confined within a polymer matrix. Such an electrolyte allows the combination of the processability advantage of polymers with the high Li-ion conductivity of liquid electrolytes, thus overcoming the primary disadvantage of solid polymer electrolytes. Coin cells with LiNi1-x-yMnxCoyO2 cathode material and the eutectogel solid electrolyte were assembled, showing promising results. To understand the performance limiting factors at the cathode and the interfaces (main focus on cathode-eutectogel interface), characterization methods and electrochemical studies have been performed using tools such as: XRD, SEM, ICP-OES, galvanostatic charge-discharge cycling and electrochemical impedance spectroscopy.