Lithium Titanate Anode Thin Films for Li‐Ion Solid State Battery Based on Garnets

Solid state electrolytes, such as Li‐Garnets, are fastest Li‐ionic conductor materials that have attracted attention for safe hybrid and full solid state battery architectures. Turning to oxide‐based low voltage anodes gives opportunities to avoid Li‐dendrite formation and also to reach full thin film microbattery architectures based on garnets as high energy density replacement for supercapacitors. Herein, it is demonstrated that Li 4 Ti 5 O 12 thin films deposited by pulsed laser deposition can show stable structures and cycling kinetics reaching almost close to theoretical capacity of 175 mAh g −1 when combined to Li 6.25 Al 0.25 La 3 Zr 2 O 12 pellets. Stable operation at room temperature with 90% of theoretical capacity retention at 2.5 mA g −1 over 22 cycles is achieved on bilayer half cell batteries. Rate capability studies show promising charge and discharge capacities and act as a case study for the well‐known Li 4 Ti 5 O 12 thin film anode, demonstrating its good compatibility with the investigated solid garnet electrolyte. This gives new perspective on the use of oxide‐based low voltage anodes for future strategies avoiding Li‐dendrite formation or safe solid state microbattery thin film assemblies based on Li‐garnets.