Zinc-iodine secondary energy storage methods, devices, and electrolytes
Disclosed are cathodes having electron-conductive high-surface-area materials, aqueous non-halide-containing electrolytes, secondary zinc-iodine energy storage devices using the same, and methods for assembling the same. The disclosed high-surface-area materials and the aqueous non-halide-containing electrolyte solutions can contribute together to the confinement of the active iodine species in the cathode and to the minimization of shuttle effects and self-discharging. The non-halide-containing electrolyte salts can facilitate preferential adsorption of the iodine species to the cathode material rather than dissolution in the aqueous electrolyte solution, thereby contributing to the confinement of the active iodine species.
1. A secondary energy storage device comprising:
an anode comprising zinc;
a cathode comprising an electron conductive, porous-material having pore diameters less than 50 nanometers and active iodine species adsorbed to the material when the device is in a non-discharged state; and
an aqueous electrolyte solution having substantially no halides when the device is in a charged state, wherein no ion selective membrane separates the anode and the cathode.
2. The secondary energy storage device of claim 1 , wherein the electron conductive, porous comprises graphene.
3. The secondary energy storage device of claim 1 , wherein the electron conductive, porous material comprises a conductive polymer material, a conductive Metal-organic framework (MOF)-based material, or a combination thereof.
4. The secondary energy storage device of claim 1 , wherein the electron conductive, porous material comprises activated carbon.
5. The secondary energy storage device of claim 1 , wherein the electron conductive porous material has pores less than or equal to 2 nm.
6. The secondary energy storage device of claim 1 , wherein the zinc comprises zinc metal.
7. The secondary energy storage device of claim 1 , wherein the zinc comprises zinc ions and the anode further comprises an intercalation material into which zinc ions are intercalated and deintercalated.
8. The secondary energy storage device of claim 7 , wherein the intercalation material comprises Mo 6 S 8 .
9. The secondary energy storage device of claim 1 , wherein the aqueous electrolyte solution comprises a non-halide-containing, electrolyte salt dissolved therein.
10. The secondary energy storage device of claim 9 , wherein the non-halide-containing, electrolyte salt comprises MSO 4 , wherein M is a metal.
11. The secondary energy storage device of claim 9 , wherein the non-halide-containing, electrolyte salt comprises M(NO 3 ) 2 , M(CF 3 SO 3 ) 2 , or M(CH 3 COO) 2 , wherein M is a metal.
12. The secondary energy storage device of claim 11 , wherein M is Zn, K, or Na or other alkaline metals.
13. The secondary energy storage device of claim 9 , wherein the non-halide-containing, electrolyte salt comprises ZnSO 4 .
14. The secondary energy storage device of claim 13 , wherein the ZnSO 4 has a concentration in the aqueous electrolyte solution greater than or equal to 0.5M.
15. The secondary energy storage device of claim 13 , wherein the ZnSO 4 has a concentration in the aqueous electrolyte solution greater than or equal to 1M, greater than or equal to 1.5M, greater than or equal to 2M, or greater than or equal to 3M.
16. The secondary energy storage device of claim 1 , having a capacity retention greater than or equal to 90% after at least 3000 cycles at a rate of 2 C.