Closed-Loop Cathode Recycling in Solid-State Batteries Enabled by Supramolecular Electrolytes

Here we show how to design supramolecular organo ionic (ORION) electrolytes that are viscoelastic solids at battery operating temperatures (–40 to 45 °C), yet are viscoelastic liquids above 100 °C, which enables both the fabrication of high quality SSBs and the recycling of their cathodes at end-of-life. Key to our success is the use of polytopic zwitterionic small molecules, which network lithium salts or solvates thereof into superconcentrated solid electrolytes with tunable viscoelasticity and ionic conductivities as high as 0.6 mS cm–1 at 45 °C. SSBs implementing ORION electrolytes alongside Li metal anodes and either LFP or NMC cathodes were operated for hundreds of cycles at 45 °C with less than 20% capacity fade after 100 cycles. Using a low-temperature solvent process, we isolated the cathode from the electrolyte and demonstrated that refurbished cells recover 90% of their initial capacity and sustain it for an additional 100 cycles with 84% capacity retention in their second life.