Ion‐Conducting Ceramics in Lithium‐Ion Batteries: From Electrode Modification to Composite Electrolytes for Quasi‐Solid‐State Cells

The development of lithium‐based batteries requires advanced electrolyte systems capable of ensuring efficient ion transport and reliable electrode–electrolyte interfaces. In this work, inorganic lithium‐ion conductors have been investigated as components of composite polymer electrolytes and as functional modifiers of Li 4 Ti 5 O 12 anodes. Li 4 Ti 5 O 12 was modified by mechanical mixing with 1 wt% of representative ion conductors, including NASICON‐type Li 1.3 Al 0.3 Ti 1.7 (PO 4 ) 3 (LATP), garnet‐type Li 6.5 La 3 Zr 1.5 Nb 0.5 O 12 (LLZNO), and perovskite‐type Li 0.5 La 0.5 TiO 3 (LLTO), intended to distribute the ceramic particles over the LTO surface as a physical (nonbonded) coating, and evaluated in lithium‐ion cells employing either a conventional liquid electrolyte or quasi‐solid‐state composite polymer electrolytes. Electrochemical characterization by galvanostatic cycling and cyclic voltammetry demonstrated distinct electrochemical behavior depending on the incorporated ceramic phase, with LATP‐containing systems showing the most favorable rate performance and overall internal resistance among the investigated modified configurations. In the quasi‐solid‐state cells, the higher internal resistance compared with liquid‐electrolyte cells limited the rate capability at high currents, while stable cycling was observed at 1C. Furthermore, laboratory‐scale quasi‐solid‐state pouch cells employing the composite polymer electrolyte delivered a discharge capacity of 159 mAh·g −1 at C/10, comparable to that of the corresponding liquid‐electrolyte cells (148 mAh·g −1 ), with ~2% first‐cycle capacity loss.