Fabrication of films and coatings used to activate shear thickening, impact resistant electrolytes

1. A method of making a passively impact resistant composite electrolyte and separator layer, comprising the steps of:

providing a porous separator material having pores and a surface;

providing a suspension composition comprising electrically non-conducting particles that enable shear thickening, the shear thickening enabling particles having a polydispersity index of no greater than 0.1, an average particle size in a range of from 50 nm to 1 um, and an absolute zeta potential of greater than ±40 mV, and a particle suspension solvent for suspending the shear thickening particles;

applying the suspension composition to a separator material, wherein a portion of the shear thickening particles and suspension solvent penetrate the pores and the remainder of the shear thickening particles in the suspension composition are distributed across the surface of the separator material; and

evaporating the suspension solvent from the separator material to provide a shear thickening particle loaded separator, wherein the shear thickening particle loaded separator comprises a particle suspension agent, the particle suspension agent comprising at least one selected from the group consisting of stabilization polymers covalently bound to the surface of the shear thickening particles, and a stabilizing surfactant, wherein the shear thickening particles have an electrochemical double layer, and the particle suspension agent has a chain length of greater than double a thickness of the electrochemical double layer.

2. The method of claim 1 , wherein the shear thickening enabling particles comprise at least one ceramic material selected from the group consisting of TiO 2 , Al 2 O 3 , ZrO 2 , Y 2 O 3 , HfO 2 , GeO 2 , Sc 2 O 3 , CeO 2 , MgO, BN and SiO 2 .

3. The method of claim 1 , wherein the suspension composition is applied to the separator by a roll to roll process.

4. The method of claim 1 , wherein the shear thickening particles have a polydispersity index of no greater than 0.09.

5. The method of claim 1 , wherein the shear thickening enabling particles have an average particle size of in a range of 100 nm to 900 nm.

6. The method of claim 1 , wherein the shear thickening enabling particles have an absolute zeta potential of greater than ±50 mV.

7. The method of claim 1 wherein said shear thickening enabling particles are free of materials that volatilize at 80° C.

8. The method of claim 1 , wherein the shear thickening enabling particles are present in the suspension composition in a range of from 20 wt. % to 60 wt. %.

9. The method of claim 1 , wherein the suspension solvent comprises at least one material selected from the group consisting of ethylene carbonate, dimethyl carbonate, propylene carbonate, dimethoxyethane, dioxolane, ethyl methyl carbonate, acetonitrile, anisole, benzene, cyclohexane, dibutyl ether, dichloromethane, diethylamine, diethyl ether, 1,2-dimethoxyethane n,n-dimethylacetamide, n,n-dimethylformamide, dimethyl sulfoxide, 1,4-dioxane, ethanol, ethyl acetate, ethyl benzoate, formamide, hexamethylphosphoramide, isopropyl alcohol, methanol, 2-methyl-2-propanol, nitrobenzene, nitromethane, pyridine, tetrahydrofuran, toluene, triethylamine, o-xylene, propylene carbonate, dimethyl carbonate, ethylene carbonate, n-methyl pyrrolidone, 3:7 ec/dmc, 50/50 ethanol/xylene, and 50/50 methanol/xylene.

10. The method of claim 1 , further comprising a step of pre-wetting the separator with a wetting solvent prior to the application of the suspension composition to the separator, the pre-wetting being sufficient to fill the pores of the separator.

11. The method of claim 1 , wherein the separator has a porosity of from 20% to 80%.

12. The method of claim 1 , wherein the porosity of the separator is from 20% to 40% after the application of the suspension composition and the evaporation step.

13. The method of claim 1 , wherein the suspension solvent has a boiling pointless than 150° C.

14. The method of claim 1 , wherein the suspension solvent has a dielectric constant of from 5 to 25.

15. The method of claim 1 , wherein the suspension solvent is stable at oxidation potentials of from 0 V versus Li/Li + to 4.9 V versus Li/Li + .

16. The method of claim 1 , wherein after the evaporation step the shear thickening enabling particles comprise from 10 wt. % to 40 wt. % of the shear thickening particle loaded separator.

17. The method of claim 1 , further comprising a step of adding battery electrolyte to the shear thickening particle loaded separator to create a shear thickening electrolyte separator assembly, wherein the shear thickening enabling particles comprise from 10 wt. % to 40 wt. % based on the total weight of the shear thickening enabling particles and the electrolyte.

18. The method of claim 1 , further comprising a step of adding an electrolyte salt to the shear thickening particle loaded separator.

19. The method of claim 18 , wherein the electrolyte salt comprises at least one material selected from the group consisting of lithium hexafluorophosphate, lithium triflate, lithium perchlorate, lithium tetrafluoro borate, lithium hexafluoro lithium arsenate, lithium bis(trifluoromethane sulphone)imide, lithium bis(oxalate) borate, sodium perchlorate, sodium tetrafluoro borate, sodium hexafluoro arsenate, sodium bis(trifluoromethane sulphone)imide, sodium bis(oxalate) borate, sodium hexafluorophosphate and sodium triflate.

20. The method of claim 1 , wherein the stabilizing surfactant comprising a first portion for adsorbing to the particles, and a second portion that is absorbed in the solvent, a length of the surfactant from the first portion to the second portion being greater than twice a thickness of the electrochemical double layer.

21. The method of claim 1 , wherein a non-porous backing is placed adjacent to one side of the porous separator prior to application of the suspension composition to the separator, and the backing is removed after the evaporation step.

22. The method of claim 1 , wherein the suspension composition has a viscosity of from 30 to 10,000 mPa.

23. The method of claim 1 , wherein between 20-40 wt. % based on the total weight of the shear thickening particles are located within the pores of the separator after the evaporation step.

24. The method of claim 1 , wherein the pores of the porous separator have an average pore diameter, and the shear thickening particles have an average hydrocluster diameter, and wherein the average pore diameter is from 1 to 100 times the size of the average hydrocluster diameter.

25. A method of making a passively impact resistant composite electrolyte and separator layer, comprising the steps of:

providing a porous separator material having pores and a surface;

providing a suspension composition comprising electrically non-conducting particles that enable shear thickening, the shear thickening enabling particles having a polydispersity index of no greater than 0.1, an average particle size in a range of from 50 nm to 1 um, and an absolute zeta potential of greater than ±40 mV, and a particle suspension solvent for suspending the shear thickening particles;

applying the suspension composition to a separator material, wherein a portion of the shear thickening particles and suspension solvent penetrate the pores;

evaporating the suspension solvent from the separator material to provide a shear thickening particle loaded separator with shear thickening particles in the pores;

wherein the pores of the porous separator have an average pore diameter, and the shear thickening particles form hydro clusters having an average hydrocluster diameter, and wherein the average pore diameter is from 1 to 100 times the size of the average hydrocluster diameter; and

wherein after the evaporation step, and after the addition of a battery electrolyte to the separator, the particles in the pores comprise between 20-40 wt. % based on the total weight of the particles and the battery electrolyte in the pores, and not including the separator weight.

26. A method of making a passively impact resistant composite electrolyte and separator layer, comprising the steps of:

providing a porous separator material having pores and a surface;

providing a suspension composition comprising electrically non-conducting particles that enable shear thickening, the shear thickening enabling particles having a polydispersity index of no greater than 0.1, an average particle size in a range of from 50 nm to 1 um, and an absolute zeta potential of greater than ±40 mV, and a particle suspension casting solvent for suspending the shear thickening particles;

wherein the suspension casting solvent has a dielectric constant of from 5 to 25, and has a boiling point of less than 150° C.;

applying the suspension composition to a separator material, wherein a portion of the shear thickening particles and suspension casting solvent penetrate the pores and the remainder of the shear thickening particles in the suspension composition are distributed across the surface of the separator material; and

evaporating the suspension casting solvent from the separator material to provide a shear thickening particle loaded separator.

27. The method of claim 26 , wherein the suspension casting solvent comprises at least one material selected from the group consisting of ethylene carbonate, dimethyl carbonate, propylene carbonate, dimethoxyethane, dioxolane, ethyl methyl carbonate, acetonitrile, anisole, benzene, cyclohexane, dibutyl ether, dichloromethane, diethylamine, diethyl ether, 1,2-dimethoxyethane n,n-dimethylacetamide, n,n-dimethylformamide, dimethyl sulfoxide, 1,4-dioxane, ethanol, ethyl acetate, ethyl benzoate, formamide, hexamethylphosphoramide, isopropyl alcohol, methanol, 2-methyl-2-propanol, nitrobenzene, nitromethane, pyridine, tetrahydrofuran, toluene, triethylamine, o-xylene, propylene carbonate, dimethyl carbonate, ethylene carbonate, n-methyl pyrrolidone, 3:7 ec/dmc, 50/50 ethanol/xylene, and 50/50 methanol/xylene.

28. The method of claim 26 , further comprising a step of adding an electrolyte salt to the shear thickening particle loaded separator.