Rechargeable Alloy Battery for Electric Vehicles

An electrochemical cell includes an anode comprising a first anode metal, an anode current collector, a cathode comprising a first cathode metal, a cathode current collector, and an electrolyte layer between the anode and the cathode. The electrolyte layer comprises a mesoporous material of polymer or glass and a salt electrolyte filling pores of the mesoporous material, wherein the pores are interconnected and the salt electrolyte is a salt of the first anode metal.

TECHNICAL FIELD

This disclosure relates to rechargeable alloy batteries for electric vehicles.

BACKGROUND

The use of lithium ion batteries has been increasing for a wide variety of applications, including electric vehicles, due in part to their high energy densities and low maintenance requirements. However, lithium ion batteries are costly to manufacture. Certain safety concerns are associated with lithium ion batteries as well. New battery chemistries that are lower in cost and overcome the safety issues are needed to replace lithium ion batteries, while achieving the performance of lithium ion batteries.

SUMMARY

Disclosed herein are implementations of rechargeable alloy batteries for electric vehicles, and in particular, electrochemical cells, a plurality of which form the rechargeable alloy batteries.

One implementation of an electrochemical cell disclosed herein includes an anode comprising a first anode metal, an anode current collector, a cathode comprising a first cathode metal, a cathode current collector, and an electrolyte layer between the anode and the cathode. The electrolyte layer comprises a mesoporous material of polymer or glass and a salt electrolyte filling pores of the mesoporous material, wherein the pores are interconnected and the salt electrolyte is a salt of the first anode metal.

Another implementation of an electrochemical cell disclosed herein includes an anode comprising a first anode metal and a second anode metal, an anode current collector, a cathode comprising a first cathode metal and a second cathode metal, a cathode current collector, and an electrolyte layer between the anode and the cathode. The electrolyte layer can include a mesoporous material of polymer or glass and a salt electrolyte filling pores of the mesoporous material, wherein the pores are interconnected and the salt electrolyte is a salt of the first anode metal. In implementations, the first anode metal can have a melting point of 100° C. or less and the second anode metal can have a melting point of 400° C. or greater. In implementations, the electrochemical cell can have an operating temperature of less than 300° C. and the first cathode metal and the first anode metal can be selected to be in liquid form during operation of the electrochemical cell while the second cathode metal and the second anode metal can be selected to be solid during operation of the electrochemical cell.

Implementations disclosed herein can further include and electrolyte layer further comprising a framework of insulating polymer extending between the anode and the cathode, the framework defining hollow columns extending from the anode and the cathode, wherein each hollow column is filled with the mesoporous material with the salt electrolyte filling the pores of the mesoporous material.

DETAILED DESCRIPTION

The use of lithium ion batteries has been increasing for a wide variety of applications, including electric vehicles, due in part to their high energy densities and low maintenance requirements. However, lithium ion batteries are costly to manufacture. Certain safety concerns are associated with lithium ion batteries as well. New battery chemistries that are lower in cost and that overcome the safety issues are needed to replace lithium ion batteries, while achieving or exceeding the performance of lithium ion batteries.

Battery chemistries such as metal alloys that are used in stationary applications have been considered as the materials are more cost effective and safer than those used in lithium ion batteries. However, some stationary battery chemistries require batteries that are large and heavy due to the amount of material required. Some stationary battery chemistries also operate at high temperatures, operating at or higher than about 600° C. The large footprint, weight and operating temperatures of these stationary batteries prohibits their use in electronic vehicles.

Disclosed herein are electrochemical cells, and batteries comprising multiple electrochemical cells, of a metal solid state design that are stackable, use available, lower-cost materials, and are safe to operate. The electrochemical cells and batteries comprising the electrochemical cells are rechargeable and meet performance, size and weight requirements for use in electric vehicles.

In an implementation of an electrochemical cell100disclosed herein and illustrated inFIG. 1, there is an anode102comprising an anode metal, an anode current collector104, a cathode106comprising a cathode metal, a cathode current collector108, and an electrolyte layer110between the anode102and the cathode106. The electrolyte layer110comprises a mesoporous material112of polymer or glass and a salt electrolyte114filling pores of the mesoporous material112. The pores of the mesoporous material112are interconnected and the salt electrolyte114is a salt of the first anode metal.

The mesoporous material112of polymer or glass has a porosity of between about 40% and 70%, inclusive, and retains the salt electrolyte114in the pores. The pores of the mesoporous material112, seen in the enlarged portion ofFIG. 1, are interconnected, creating pathways of electrolyte through the electrolyte layer110between the anode102and the cathode106. The salt electrolyte114is selected based on the anode metal. For example, if the anode metal is lithium, the salt electrolyte114is lithium chloride.

In another implementation of an electrochemical cell200disclosed herein and illustrated inFIG. 2, the electrolyte layer110ofFIG. 1is modified to include structural support. In the electrochemical cell200inFIG. 2, there is an anode202comprising an anode metal, an anode current collector204, a cathode206comprising a cathode metal, a cathode current collector208, and an electrolyte layer210between the anode202and the cathode206. The electrolyte layer210comprises a framework212of insulating polymer extending between the anode202and the cathode206. The framework212, seen in plan view inFIG. 3, defines hollow columns214extending from the anode202and the cathode206. Each hollow column214is filled with mesoporous material216, with salt electrolyte218filling the pores of the mesoporous material216. The framework212is made of an insulating polymer such as polytetrafluoroethylene. The framework212provides additional mechanical structural strength to the electrochemical cell200during operation as the anode metal and cathode metal are in a molten state during operation. The total volume of the hollow columns214should be as large as possible while maintaining structural strength of the framework212surrounding hollow columns214.

The mesoporous material216is polymer or glass, the polymer being the same or different than that of the framework212. The mesoporous material216of polymer or glass has a porosity of between about 40% and 70%, inclusive, and retains the salt electrolyte218in the pores. The pores of the mesoporous material216, seen in the enlarged portion ofFIG. 1, are interconnected, creating pathways of electrolyte through the electrolyte layer210between the anode202and the cathode206. The salt electrolyte218is selected based on the anode metal. For example, if the anode metal is lithium, the salt electrolyte218is lithium chloride.

The anode metal of anode202is selected from the group consisting of lithium, sodium, potassium, rubidium, caesium, magnesium, calcium, strontium, and barium. The anode current collector204can be, for example, copper. The cathode metal of cathode206is selected from the group consisting of aluminum, gallium, indium, titanium, zinc, cadmium, mercury, tin, lead, antimony, bismuth, and tellurium. The cathode current collector208can be, for example, aluminum. In a non-limiting example, the anode metal is lithium, the cathode metal is gallium, and the salt electrolyte is lithium chloride.

Another implementation of an electrochemical cell300is described with respect toFIG. 4. The electrochemical cell400has the same electrolyte layer110as that with respect to electrochemical cell100, with structural support added to the anode and cathode as described herein. The electrochemical cell400comprises an anode402comprising a first anode metal420and a second anode metal422, an anode current collector404, a cathode406comprising a first cathode metal424and a second cathode metal426, a cathode current collector408, and an electrolyte layer410between the anode402and the cathode406. The electrolyte layer410comprises a mesoporous material412of polymer or glass and a salt electrolyte414filling pores of the mesoporous material412, wherein the pores are interconnected and the salt electrolyte414is a salt of the first anode metal420.

The mesoporous material412of polymer or glass has a porosity of between about 40% and 70%, inclusive, and retains the salt electrolyte414in the pores. The pores of the mesoporous material412, seen in the enlarged portion ofFIG. 4, are interconnected, creating pathways of electrolyte through the electrolyte layer410between the anode402and the cathode406. The salt electrolyte414is selected based on the first anode metal420. For example, if the first anode metal420is lithium, the salt electrolyte414is lithium chloride.

In the electrochemical cell400, the second anode metal422and the anode current collector204are of the same metal and the first anode metal420has a lower melting point than the second anode metal422. The second anode metal422is formed in isolated columns430extending between the anode current collector404and the electrolyte layer410. The term “isolated columns430” as used herein means the columns are isolated from each other and each is surrounded by the first anode metal420. The electrochemical cell400has an operating temperature of less than about 300° C., typically between about 30° C. and 300° C. The first cathode metal424and the first anode metal420are selected to be in liquid form during operation of the electrochemical cell400while the second cathode metal426and the second anode metal422are selected to be solid during operation of the electrochemical cell400. The isolated columns430of the second anode material422provide structural support to the anode during operation, when the first anode material420is molten. The isolated columns430in total are between about 20% and 30% volume of the anode402, with the first anode metal420being between about 70% and 80% volume of the anode402. The isolated columns430can be uniformly spaced along the anode402as illustrated or can be non-uniformly spaced, so long as the requisite structural support to the anode402is provided. The isolated columns430can be round or can be in other shapes. The isolated columns430can also be walls that extend along a dimension of the anode402.

In the electrochemical cell400, the second cathode metal426and the cathode current collector208are of the same metal and the first cathode metal424has a lower melting point than the second cathode metal426. The second cathode metal426is formed in isolated columns432extending between the cathode current collector408and the electrolyte layer410. The term “isolated columns432” as used herein means the columns are isolated from each other and each is surrounded by the first cathode metal424. The electrochemical cell400has an operating temperature of less than about 300° C., typically between about 30° C. and 300° C. The first cathode metal424and the first anode metal420are selected to be in liquid form during operation of the electrochemical cell400while the second cathode metal426and the second anode metal422are selected to be solid during operation of the electrochemical cell400. The isolated columns432of the second cathode material426provide structural support to the cathode during operation, when the first cathode material424is molten. The isolated columns432in total are between about 20% and 30% volume of the cathode406, with the first cathode metal424being between about 70% and 80% volume of the cathode406. The isolated columns432can be uniformly spaced along the cathode406as illustrated or can be non-uniformly spaced, so long as the requisite structural support to the cathode406is provided. The isolated columns432can be round or can be in other shapes. The isolated columns432can also be walls that extend along a dimension of the cathode406.

The isolated columns430of the anode402and the isolated columns432of the cathode406can extend to and/or slightly into the electrolyte layer410. The isolated columns430of the anode402and the isolated columns432of the cathode406can be formed to prevent the respective molten first anode metal420and first cathode metal424from flowing during operation, acting as channels to the electrolyte layer410. The isolated columns432of the cathode406and the isolated columns430of the anode402can be aligned from one another on opposing sides of the electrolyte layer410as illustrated inFIG. 4. This structure reduces the ohmic resistance of the electrolyte layer410.

During operation of the electrochemical cell400, the isolated columns430of the anode402and the isolated columns432of the cathode406can extend into the electrolyte layer110, an example of which is shown inFIG. 4. During operation of the electrochemical cell400, the first anode metal420will vary in volume during charge/discharge and the first cathode metal424will include vary in volume during charge/discharge as a liquid alloy is formed of the first cathode metal424and the first anode metal420in the cathode406. Having the isolated columns430,432extend slightly into the electrolyte layer410can account for these volume changes, keeping the structural integrity of the electrochemical cell400and continuing to reduce the ohmic resistance of the electrolyte layer410. The isolated columns430,432can be formed on the respective current collector with any known deposition method, including 3D printing. The second anode metal422and second cathode metal426can be deposited to have a conical end as illustrated inFIG. 4, or the ends of the isolated columns430,432can be flat or rounded, as non-limiting examples.

The second cathode metal426and the cathode current collector408can be aluminum, as a non-limiting example. The first cathode metal424is selected from the group consisting of aluminum, gallium, indium, titanium, zinc, cadmium, mercury, tin, lead, antimony, bismuth, and tellurium. The second anode metal422and the anode current collector404can be copper, as a non-limiting example. The first anode metal420is selected from the group consisting of lithium, sodium, potassium, rubidium, caesium, magnesium, calcium, strontium, and barium. As a non-limiting example, the first anode metal420can be lithium and the first cathode material424can be gallium, with the salt electrolyte414being lithium chloride.

The electrochemical cells disclosed herein can be stacked to form a battery or battery pack. The electrochemical cells can be stacked such that adjacent electrochemical cells share a common current collector. As one example, a second electrochemical cell can be stacked on a first electrochemical cell such that the anode current collector is shared between anodes of the first and second electrochemical cell, and a third electrochemical cell can be stacked on the second electrochemical cell such that the cathode current collector is shared between cathodes of the second and third electrochemical cells.