Electrochemical energy storage devices
Provided herein are energy storage devices. In some cases, the energy storage devices are capable of being transported on a vehicle and storing a large amount of energy. An energy storage device is provided comprising at least one liquid metal electrode, an energy storage capacity of at least about 1 MWh and a response time less than or equal to about 100 milliseconds (ms).
1. An electrochemical energy storage device, comprising:
a container including a reactive material and an electrolyte comprising a molten salt, wherein said container has a surface area-to-volume ratio of less than or equal to about 100 m −1 , and wherein said molten salt is a liquid or a vapor at an operating temperature of at least 100° C.; and
a sealing unit configured to seal said container from an environment external to said container, wherein said seal comprises:
a ceramic material exposed to said reactive material or said molten salt, wherein said ceramic material is chemically resistant to said reactive material and said molten salt at said operating temperature, and wherein said ceramic material comprises an element capable of forming a first compound with said reactive material, and wherein said ceramic material has a normalized Gibbs free energy of formation (ΔG r,n ) that is more negative than a ΔG r,n of said first compound of said reactive material;
a metal collar disposed adjacent to said ceramic material; and
a metal braze disposed between said ceramic material and at least one of said metal collar and said container, wherein said metal braze comprises at least one metal that chemically reduces said ceramic material.
2. The electrochemical energy storage device of claim 1 , wherein said reactive material comprises a positive electrode and a negative electrode, and wherein said electrolyte is disposed between said positive electrode and said negative electrode.
3. The electrochemical energy storage device of claim 1 , wherein said reactive material comprises calcium, lithium, or a combination of calcium and lithium.
4. The electrochemical energy storage device of claim 1 , wherein said seal is chemically resistant to lithium vapor at a temperature of at least 350° C.
5. The electrochemical energy storage device of claim 1 , wherein said seal is chemically resistant to calcium vapor at a temperature of at least 350° C.
6. The electrochemical energy storage device of claim 1 , wherein said ceramic material is electrically isolating.
7. The electrochemical energy storage device of claim 1 , wherein said metal braze comprises silver, aluminum, or a mixture of silver and aluminum.
8. The electrochemical energy storage device of claim 1 , wherein said metal braze comprises titanium or zirconium.
9. The electrochemical energy storage device of claim 1 , wherein said ceramic material comprises aluminum nitride.
10. The electrochemical energy storage device of claim 1 , wherein said metal collar comprises a bend configured to relieve strain due to coefficient of thermal expansion mismatch between said container and said ceramic material.
11. The electrochemical energy storage device of claim 1 , wherein said metal collar is formed from stainless steel or zirconium.
12. The electrochemical energy storage device of claim 1 , further comprising a conductor adjacent to said seal, wherein said seal electrically isolates said conductor from said container.
13. The electrochemical energy storage device of claim 12 , wherein a coefficient of thermal expansion of said seal is less than 10% different than a coefficient of thermal expansion of said container or said conductor.
14. The electrochemical energy storage device of claim 1 , wherein said metal braze is capable of forming a second compound including a element, and wherein a ΔG r,n of said second compound of said metal braze is more negative than said ΔG r,n of said ceramic material.
15. The electrochemical energy storage device of claim 1 , wherein said element is nitrogen, oxygen, or sulfur.
16. The electrochemical energy storage device of claim 1 , wherein said seal comprises a first metal collar and a second metal collar.
17. The electrochemical energy storage device of claim 16 , wherein said first metal collar is joined to said ceramic material and said second metal collar is joined to said container.
18. The electrochemical energy storage device of claim 16 , wherein said seal further comprises a third metal collar joined to said ceramic material and an electrically conductive feed-through extending into said container, and wherein said third metal collar electrically isolates said electrically conductive feed-through from said container.