Preparation of thick-film electrode-solid electrolyte composites on Li7La3Zr2O12 and their electrochemical properties

•Electrode–solid electrolyte composite films up to 20 μm are prepared on Li7La3Zr2O12.•Thickness of mutual diffusion layer in the composite is ca. 5 nm.•All-solid-state battery has capacity retention of 99.97% per cycle at 100 ° C.•The battery delivered discharge capacity even at 1 mA cm−2.

We prepared up to 20 μm-thick LiNi1/3Co1/3Mn1/3O2 (NMC)-Li+ conductive glass–ceramic solid electrolyte (LATP: σLi+σLi+ ∼ 10−3 S cm−2 at 298 K) composite cathode films on Li7La3Zr2O12 (LLZ) substrates by aerosol deposition (AD) and investigated their electrochemical properties as all-solid-state batteries. The resultant NMC/LATP interface in the composite film had a thin mutual diffusion layer (∼5 nm) and a film had a porosity of ca. 0.15% in volume. The composite films were well adhered to the LLZ substrates even though the films were prepared at room temperature. All-solid-state batteries, consisting of Li/LLZ/NMC-LATP composite film (20 μm), repeated charge–discharge reactions for 90 cycles at 100 °C at a 1/10 C rate (capacity retention: 99.97%/cycle). Rate capability of this battery was improved by modifying both the LATP and electron conductive source amount in the composite film, and a battery with 16 μm-thick composite electrode delivered 60 mAh g−1 at 1 mA cm−2.