Reactive sintering of ceramic lithium ion electrolyte membranes
Disclosed herein are methods for making a solid lithium ion electrolyte membrane, the methods comprising combining a first reactant chosen from amorphous, glassy, or low melting temperature solid reactants with a second reactant chosen from refractory oxides to form a mixture; heating the mixture to a first temperature to form a homogenized composite, wherein the first temperature is between a glass transition temperature of the first reactant and a crystallization onset temperature of the mixture; milling the homogenized composite to form homogenized particles; casting the homogenized particles to form a green body; and sintering the green body at a second temperature to form a solid membrane. Solid lithium ion electrolyte membranes manufactured according to these methods are also disclosed herein.
1. A method for making a solid lithium ion electrolyte membrane, comprising:
combining a first reactant chosen from lithium phosphate glasses, germanium phosphate glasses, lithium aluminum phosphate glasses, and crystallized lithium aluminum phosphate ceramics with a second reactant chosen from refractory oxides to form a mixture;
heating the mixture to a first temperature to form a homogenized composite comprising unreacted first and second reactants, wherein the first temperature is between a glass transition temperature of the first reactant and a crystallization onset temperature of the mixture;
milling the homogenized composite to form homogenized particles;
casting the homogenized particles to form a green body; and
reactively sintering the green body at a second temperature to form a solid membrane.
2. The method of claim 1 , wherein the first reactant further comprises an oxide modifier.
3. The method of claim 2 , wherein the oxide modifier is chosen from TiO 2 , GeO 2 , SiO 2 , B 2 O 3 , Fe 2 O 3 , Nb 2 O 5 , V 2 O 5 , Sb 2 O 3 , CoO, WO 3 , SnO 2 , and combinations thereof.
4. The method of claim 1 , wherein the first reactant is lithium aluminum phosphate.
5. The method of claim 1 , wherein the second reactant is chosen from TiO 2 , SnO 2 , GeO 2 , and combinations thereof.
6. The method of claim 1 , wherein the first reactant has an average particle size of less than about 10 microns, and the second reactant has an average particle size of less than about 1 micron.
7. The method of claim 1 , wherein the first temperature is at least about 350° C.
8. The method of claim 1 , wherein the first temperature ranges from about 350° C. to about 550° C.
9. The method of claim 1 , wherein the homogenized particles have an average diameter ranging from about 1 micron to about 2 microns.
10. The method of claim 1 , wherein the second temperature is less than about 1100° C.
11. The method of claim 1 , wherein casting comprises tape casting the homogenized particles to form a green tape.
12. The method of claim 1 , wherein the solid membrane has a thickness of less than about 200 microns, a density of at least about 95% of a theoretical density of the solid membrane, and a conductivity of at least about 1×10 −4 S/cm.
13. The method of claim 1 , wherein the solid membrane is substantially flat.
14. The method of claim 13 , wherein the method does not comprise a flattening step after the sintering step.