Seamless Stitching of Redox Windows to Enable High-Voltage Resilient Solid Sodium Ion Batteries

While sulfide solid electrolytes such as Na 11 Sn 2 PS 12 can allow fast transport of Na + ions, their utilization in solid sodium ion batteries is rather unsuccessful since they are not electrochemically compatible to both high-voltage cathodes and sodium metal anode. In this work, we devise an effective approach toward realizing solid sodium ion batteries, using the Na 11 Sn 2 PS 12 electrolyte and slurry-coated NASICON-type Na 3 MnTi(PO 4 ) 3 @C as high-voltage cathode, highly beneficial for low processing cost and high content/loading of active cathode matter. We report that through significantly improved integrity of electrolyte-cathode interface, such solid sodium ion batteries can deliver outstanding cycling and rate performance, with a charge voltage resilience up to 4.1 V, a high cathode discharge capacity of 128.7 mAh g −1 against the Na 3 MnTi(PO 4 ) 3 @C in cathode is achieved at 0.05 C, and capacity retention ratio of 82% with a rate of 0.1 C is realized after prolonged cycling at room temperature. Besides, we demonstrate that such a solid sodium ion battery can even perform at a sub-zero Celsius temperature of −10°C, when the conventional control cell using liquid electrolyte completely fail to function. This work is to offer a dependable avenue in engineering next generation of safe solid ion batteries based on highly sustainable and much cheaper material resources.