The direct crystallization of a closo-borate solid electrolyte from solution is demonstrated and applied to infiltrate porous battery electrodes fabricated by traditional slurry casting methods. Employing isopropanol as a solvent, we show that Na4(B12H12)(B10H10) crystallizes inside the open porosity of the electrodes with the appropriate crystal structure yielding high ionic conductivity (1 mS cm-1 at 25 °C) and providing efficient contact to the active materials. Very stable cycling is demonstrated at 30 °C for NaCrO2|Na-Sn half cells employing infiltrated NaCrO2 cathodes with mass loadings of ~7.7 mg cm-2 at rates up to 5C (4.5 mA cm-2). The all-solid-state cells exhibit remarkable cycling stability at moderate (70 MPa), and low (3 MPa) applied external pressure, retaining 95.6% and 85.9% of the initial capacity after 100 cycles at 0.5C respectively. A NaCrO2|Sn rocking-chair all-solid-state full cell with capacity-balanced infiltrated electrodes is also demonstrated. The more pronounced fading of the full cell is characterized with a three-electrode measurement and can be attributed to the poorer cyclability of Sn. This work bridges the gap between the attractive materials properties of closo-borate electrolytes and their integration into all-solid-state batteries facilitating their adoption in industrial cell production at scale.
Bibliographical noteFunding Information:
L.D., R.M., H.H, A.R, and C. B. thank the Swiss National Science Foundation (SNSF) for financial support for the Sinergia project ‘Novel ionic conductors’ under contract number CRSII2_160749/1 . This work was further partially supported by InnoSuisse through funding for the Swiss Competence Center for Energy Research (SCCER) Heat and Electricity Storage under contract number 1155-002545. L.D . thanks the Korean National Research Foundation (NRF) for a young researcher’s exchange grant. Y.S.J. was supported by the Technology Development Program to Solve Climate Changes and by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT & Future Planning (Nos. NRF-2017M1A2A2044501 and NRF-2018R1A2B6004996 ).
© 2019 Elsevier B.V.
All Science Journal Classification (ASJC) codes
- Renewable Energy, Sustainability and the Environment
- Materials Science(all)
- Energy Engineering and Power Technology