Polymer electrolytes provide a safe solution for all-solid-state high energy density batteries. Materials that meet the simultaneous requirement of high ionic conductivity and high transference number remain a challenge, in particular for new battery chemistries beyond Lithium such as Na, K and Mg. Herein, we demonstrate the versatility of a polymeric ionic liquid (PolyIL) as a solid-state solvent to achieve this goal for both Na and K. Using molecular simulations, we predict and elucidate fast metal ion transport in PolyILs through a structural diffusion mechanism in a polymer-in-salt environment, facilitating a high transference number. Experimental validation of these computational designed Na and K polymer electrolytes gives high ionic conductivities of 1.010-3 S cm-1 at 80 oC and an exceptional Na+ transference number of ~0.57. Electrochemical cycling of a sodium anode also demonstrates an ultra-low overpotential of 40 mV and stable long term performance of more than 100 hours in a symmetric cell. PolyIL-based polymer-in-salt strategies for novel solid-state electrolytes thus offer a promising route to design high performance next generation sustainable battery chemistries.

Figure 1

Figure 2

Figure 3

Figure 4
There is NO Competing Interest.
This is a list of supplementary files associated with this preprint. Click to download.
supplementary information
Loading...
Posted 25 May, 2021
Posted 25 May, 2021
Polymer electrolytes provide a safe solution for all-solid-state high energy density batteries. Materials that meet the simultaneous requirement of high ionic conductivity and high transference number remain a challenge, in particular for new battery chemistries beyond Lithium such as Na, K and Mg. Herein, we demonstrate the versatility of a polymeric ionic liquid (PolyIL) as a solid-state solvent to achieve this goal for both Na and K. Using molecular simulations, we predict and elucidate fast metal ion transport in PolyILs through a structural diffusion mechanism in a polymer-in-salt environment, facilitating a high transference number. Experimental validation of these computational designed Na and K polymer electrolytes gives high ionic conductivities of 1.010-3 S cm-1 at 80 oC and an exceptional Na+ transference number of ~0.57. Electrochemical cycling of a sodium anode also demonstrates an ultra-low overpotential of 40 mV and stable long term performance of more than 100 hours in a symmetric cell. PolyIL-based polymer-in-salt strategies for novel solid-state electrolytes thus offer a promising route to design high performance next generation sustainable battery chemistries.

Figure 1

Figure 2

Figure 3

Figure 4
There is NO Competing Interest.
This is a list of supplementary files associated with this preprint. Click to download.
supplementary information
Loading...