In order to increase the industrial appeal of solid-state batteries (SSBs) based on garnet Li₇La₃Zr₂O₁₂ (LLZO), the possibility of manufacturing them using scalable production processes such as tape casting must be demonstrated. In particular, the scalable production of thick, high-capacity oxide-ceramic composite cathodes based on Ni-rich LiNi_xMn_yCo_zO₂ (NMC) remains a key challenge on the path to realizing ceramic SSBs with competitive energy densities. The limited thermal compatibility between NMC and LLZO during sintering requires the use of a sintering aid such as Li₃BO₃ (LBO), which, however, impairs the rheological stability of tape casting slurries. In this work, we have developed a new tape-casting process for thick oxide-ceramic composite cathodes by establishing a slurry formulation that is compatible with multiphase cathode compositions and enables the reproducible fabrication of composite NMC cathode tapes with high active material loading. Two cathode configurations are investigated: NMC-LLZO-LBO composite cathodes, where LLZO serves as the catholyte, and LLZO-free NMC-LBO cathodes. After cosintering, the residual porosity of the ceramic cathodes is infiltrated with a polymer electrolyte with and without conductive carbon additives to form hybrid polymer-ceramic SSBs. By systematically correlating cathode chemistry, secondary phase formation, and electrochemical performance, this study demonstrates how cathode chemistry and the balance between ionic and electronic transport pathways influence capacity utilization and cycle stability in thick, tape-cast NMC-based composite cathodes.

Nanocrystalline cellulose (NCC) is an abundant biogenic nanomaterial with unique properties that enables the efficient synthesis of mesoporous crystalline titania. We significantly enhance the photocatalytic activity of titania thin films by introducing solvothermally synthesized preformed anatase nanoparticles into a sol-gel based biotemplated titania scaffold. The resulting dual source titania thin films containing different amounts of preformed crystalline species were investigated by time-resolved microwave conductivity (TRMC) measurements and tested in the photocatalytic conversion of 4-chlorophenol. The gradual addition of preformed nanoparticles leads to a consistent increase of the mean size of titania crystalline domains, whereas the porosity of the composite is well-preserved due to the shape-persistent nature of the NCC template. Microwave conductivity studies establish increased photoconductivity of the films containing preformed anatase nanoparticles in comparison to that of films made without the nanoparticles. The synergistic features of the dual source titania, namely the improved crystalline properties brought by the preformed nanocrystals in combination with the high surface area provided by the NCC-templated sol-gel titania, result in a very high photocatalytic activity of the films in the photocatalytic decomposition of 4-chlorophenol. In quantitative terms, the dual source titania films prepared with 75% nanoparticles exhibit a first order degradation rate constant of 0.53 h^-1 (1.47 × 10^-4 sec^-1), which strongly outperforms the activity of commercial P90 nanopowder showing a rate constant of 0.17 h^-1 (0.47 × 10^-4 sec^-1) under the same conditions.