Room-temperature all-solid-state sodium batteries with robust ceramic interface between rigid electrolyte and electrode materials

All-solid-state sodium batteries (Na-ASSBs) are regarded as an ecologic and economical alternative to their Li congeners for stationary applications. Ceramic-based Na-ASSBs benefit from the high conductivity of the oxide Na-ion conductors used as electrolyte, as well as from their good mechanical, chemical and thermodynamic stability. However, so far Na-ASSBs suffer from severe contact problems in the positive electrodes and subsequently unsatisfactory cell performance. In this report, the inter-ceramic contact problems are solved by combining the infiltration of a porous electrolyte scaffold by precursor solution with in situ synthesis of electrode active material (chemical infiltration) to fabricate model cells using Na3V2P3O12 (NVP), Na3.4Zr2Si2.4P0.6O12 (NZSP) and Na as the positive electrode, electrolyte and negative electrode materials, respectively. Optimized interface between NVP nano layer and NZSP backbone was formed, providing effective ion transfer and minimizing the stress caused by volume change of electrode active material during charging and discharging processes. The interface resulted in a highly stable battery performance at 25 degrees C. The performances, achieved without using any liquid or polymer phase as an accommodation medium, suggest a promising future for chemical infiltration as fabrication process for ceramic-based ASSBs.