(Invited) Different Designs for Ta-Doped Llzo Based Solid State Battery Prepared By Tape-Casting

Abstract

One pathway for moving forward from current Li-ion battery technology based on organic liquid electrolytes to next-generation battery design can be implementation of solid state electrolyte along with Li metal based negative electrode. This step would result in a battery with higher energy density and improved safety.One promising candidate material for ceramic electrolyte is garnet-type oxide LLZO (Li7La3Zr2O12) due to its relatively good chemical stability which allows relaxed requirements for processing and handling. Additionally, the doped LLZO has sufficiently good Li+ ionic conductivity (0.1 – 1 mS/cm at room temperature) and exhibits (electro-)chemical stability with the electrode materials currently under focus. To achieve low resistance values, the LLZO electrolyte needs to be prepared as a thin layer with high density. In order to integrate fabrication of LLZO electrolyte into industrial manufacturing, tape-casting can be considered as one of the low-cost scalable method for producing ceramic layers.In this study tape-casting was used to produce Ta-doped LLZO electrolyte layers with relative density of 98% and total conductivity of 0.3 mS/cm at room temperature. In order to obtain Li/LLZO/Li symmetrical cells, interfacial treatment was used for surface of LLZO to achieve good contact and low interfacial resistance with Li metal electrode. Current densities up to 300 µA/cm2 were achieved during galvanostatic cycling for flat LLZO pellet sample at 40 °C. The cell was galvanostatically cycled with high stability for long term at current density of 100 µA/cm2.Another design that can be considered for LLZO-based solid state battery is porous-dense-porous multilayers. This architecture has the advantage to provide support for electrolyte layer allowing to reduce its thickness and also increases the interfacial surface area which will reduce interfacial resistance. The described design allows to obtain lower resistance for the solid state battery with higher accessible current densities (>1mA/cm2), thus providing higher performance.