ELECTRODE INCLUDING DIMENSION RETAINER FOR SOLID-STATE BATTERY

An electrode is provided that includes a current collector, at least one column and an electrode material. The at least one column is formed of a foam material. The electrode material is disposed on the current collector and includes an electrode active material. Each of the at least one column is disposed within and extending from a surface of the current collector.

BACKGROUND

Field of the Invention

The present invention generally relates to an electrode including a dimension retainer for a solid-state battery, and a solid-state battery including the electrode with the dimension retainer. The electrode includes a current collector, at least one column, and an electrode material comprising an electrode active material. The at least one column is formed of a foam material, and the electrode material is disposed on the current collector. Each of the at least one column is disposed within and extending from a surface of the current collector.

Background Information

Lithium-based batteries that include lithium metal anodes or lithium-based cathode material are desirable because they have a high energy density and, thus, can generate a large amount of power with a relatively thin electrode structure, thus permitting a reduction in the size of the battery as compared with other conventional batteries including anodes made of carbon or silicon. Lithium-based batteries use lithium metal anodes and cathodes formed of complex oxides such as lithium nickel manganese cobalt oxide (LiNiMnCoO2, also commonly referred to as “NMC”). However, there are several drawbacks with lithium metal anodes. For example, the performance of lithium metal anodes is limited by current density as such anodes are prone to excessive dendritic growth and accumulation of dead lithium resulting in severe volume expansion of lithium metal anodes in the battery.

In order to improve the safety and energy storage capacity of lithium-based batteries, solid-state batteries have been developed that use a solid or polymer electrolyte to conduct lithium ions between the anode and cathode. Solid-state batteries allow for a much smaller battery size due to their improved energy density. Solid state lithium-based batteries also have an improved safety performance, an enhanced life cycle and higher charge/discharge rates as compared with conventional lithium-ion batteries using a liquid electrolyte, which can lead to undesirable dendrite formation and short-circuiting.

With respect to solid-state lithium-ion batteries, it has been discovered that anode-free solid-state batteries, in which a bare anode current collector is used and a lithium metal anode is formed on the current collector during charging of the battery, have the highest energy density and are therefore the most desirable. For example, conventional anode-free lithium-based solid-state batteries use a cathode formed of a lithium-ion material, such as lithium nickel manganese cobalt oxide (NMC), mixed with solid electrolyte, and a bare anode current collector. In such anode-free batteries, there is no lithium present initially—instead, the lithium metal anode is formed by precipitation from the intercalated lithium in the cathode active material. However, one problem with these conventional anode-free batteries is that they typically have an approximately 30 μm change in expansion or thickness, i.e., a 4-10% change in overall thickness, during charging due to formation of the anode.

Even when a solid-state battery is used that includes an anode initially, expansion and contraction of the battery can also be caused by lithium intercalation of the anode active material(s), for example carbon host materials, or by an increase in the volume of the electrode due to irreversible reaction deposits. Expansion and contraction can also be caused by dead volume and pressure changes within the cell case due to the battery structure and construction.

These dimensional changes in the battery due to expansion and contraction can impact the operation of the battery, the stacking of the battery cells in the final module, and the system integration. The expansion and contraction of the battery can also cause contact issues between the battery layers, thereby reducing the cycle life of the battery. Some conventional solid-state batteries have attempted to use high pressure to reduce the change in expansion. Alternatively, other solid-state batteries have included a protective polymer layer between the anode and the solid electrolyte layer.

However, there are several drawbacks with conventional protective polymer layers for lithium-ion solid-state batteries. For example, the polymer material can reduce the conductivity of the electrode materials and undesirably react with the solid electrolyte material. Furthermore, addition of the polymer material between the active material layers can reduce the energy density of the battery. The protective polymer layer also fails to sufficiently accommodate the 4-10% change in the dimensions of the battery.

Therefore, further improvement is needed to sufficiently accommodate the dimensional changes in solid-state batteries during charging and discharging. In particular, it is desirable to compensate for the expansion and pressure increase in the battery during charging and thereby prevent any contact issues between the layers after the discharge step when the anode layer goes away.

SUMMARY

It has been discovered that the dimensional changes in the battery during charging and discharging can be compensated for by providing column(s) extending from a surface of one or both of the electrode current collectors. The columns can be provided on one or both of the electrode current collectors and are formed of a foam or cushion material. The columns are provided within cavities of the current collector and extend from those cavities throughout the electrode. By providing the foam cushion columns on one or both of the current collectors, the volume changes in the solid-state battery can be reduced from approximately 4-10% to 1-2% because the foam cushion absorbs the pressure increase and acts as a spring that can contract under pressure, for example when an anode is formed during charging, and can re-expand when the pressure is reduced, for example, when the lithium metal anode disappears during discharging. In addition, the foam cushion can absorb the decomposed species in the battery. Furthermore, the foam cushion has a porosity of at least 80% and is stable in lithium such that it can withstand several cycles without degradation.

Therefore, it is desirable to provide a lithium-ion battery, such as an all-solid-state battery, that includes such an electrode in which foam cushion columns are provided within and extending from a surface of the current collector.

In view of the state of the known technology, one aspect of the present disclosure is to provide an electrode having a foam cushion. The electrode includes a current collector, at least one column formed of a foam material, and an electrode material. The electrode material is disposed on the current collector, and the electrode material comprises an electrode active material. Each of the at least one column is disposed within and extending from a surface of the current collector. By providing the at least one column extending from the current collector, volume changes in the battery during charging and discharging can be reduced as compared with conventional solid-state batteries.

Another aspect of the present disclosure is to provide a battery including an electrode having a foam cushion. The battery includes a cathode, an anode and an electrolyte disposed between the cathode and the anode. At least one of the anode and the cathode includes a current collector, at least one column formed of a foam material, and an electrode material. The electrode material is disposed on the current collector, and the electrode material comprises an electrode active material. Each of the at least one column is disposed within and extending from a surface of the current collector.

A further aspect of the present disclosure is to provide a method of forming an electrode having a foam cushion. The method includes forming at least one cavity in a surface of a current collector, applying a precursor material in each of the at least one cavity, growing the precursor material in each of the at least one cavity, and forming an electrode active material on the surface of the current collector. The precursor material is grown to a column that extends a prescribed height above the surface of the current collector, and the column is formed of a foam material.

By providing the columns formed of foam material extending from a surface of the current collector, the pressure increase and decrease during charging and discharging of the solid-state battery can be accommodated. Thus, the foam columns act as a dimension retainer on one or both of the electrodes to thereby reduce the volume change in the battery during cycling. Furthermore, by providing the foam columns within the surface of the current collector, for example, within cavities formed in the current collector, the foam columns are more firmly and stably secured to the current collector such that they are not displaced during cycling.

DETAILED DESCRIPTION OF EMBODIMENTS

Referring initially toFIG.1(a), a solid-state battery1is illustrated before charging in accordance with a first embodiment. The solid-state battery1includes a first metal support2, a cathode4, an electrolyte16, and a second metal support18. The solid-state battery1can be incorporated in a vehicle, a mobile device, a laptop computer or other suitable personal electronic device. The solid-state battery1is preferably an all-solid-state battery.

The first metal support2is formed of any suitable metal material, such as aluminum or copper, preferably aluminum. The first metal support2has a thickness ranging from 60 μm to 100 μm, preferably 60 μm. The first metal support2has a circular shape, but it should be understood that the first metal support2may have any suitable shape, such as a square or rectangular shape.

As shown inFIG.1(a), the cathode4includes a cathode current collector6, a plurality of columns8extending from the bottom surface of the cathode current collector6, catholyte particles10, additive particles12, and cathode active material particles14. The cathode current collector6is formed of any suitable metal material, such as aluminum or copper, preferably aluminum. The cathode current collector6has a thickness ranging from 60 μm to 100 μm, preferably 60 μm.

The columns8are formed within and extending from the bottom surface of the cathode current collector6. The columns8are spaced apart from each other and may be formed in any suitable pattern, as long as the columns8cover approximately 20-30% of the surface area of the cathode current collector6, preferably 25% of the surface area of the cathode current collector6. The columns8are preferably formed in a pattern such that they do not cover a central area of the bottom surface of the cathode current collector6. The columns8are also preferably formed in a pie-shaped pattern or a circular pattern.

Each of the columns8has a same prescribed diameter and length extending from a first end within the bottom surface of the cathode current collector6to an opposite end Preferably, each of the columns8has a prescribed length of at least 75% of the total thickness of the cathode4. In this embodiment, the columns8do not extend throughout the entire thickness of the cathode4such that they are in contact with the electrolyte16. However, it should be understood that the columns8may extend throughout the entire thickness of the cathode4and be in contact with the electrolyte16. Furthermore, it should be understood that the columns8may have different lengths extending from the first end within the bottom surface of the cathode current collector6to the opposite end, as long as each of the columns8has a prescribed length of at least 75% of the total thickness of the cathode4. Each of the columns8has a prescribed length of 10 μm to 30 μm, preferably 20 μm, and a prescribed diameter of approximately 1 μm to 5 μm, preferably 3 μm.

The columns8are formed of a foam material. The foam material may be any suitable foam material that acts as a cushion. For example, the foam material has a porosity of 80% or more, is stable in lithium, and can withstand several cycles without degradation. The foam material is preferably formed of polystyrene, polyurethane, glass wool, or a mixture thereof.

The columns8may be formed in the cathode current collector6in any suitable manner, for example using a laser to perform laser etching and form cavities in the cathode current collector6and filling the cavities with the foam material or a precursor for the foam material.

The catholyte particles10are formed of any suitable catholyte material for a solid-state battery. For example, the catholyte material may be any suitable lithium-ion conductive solid electrolyte material. In particular, the catholyte material can be a sulfide-based solid electrolyte, such as Li6PS5Cl, an oxide solid electrolyte, or a hybrid solid electrolyte that includes a sulfide-based solid electrolyte and a polyethylene oxide (“PEO”) based polymer. The catholyte particles10have a size ranging from approximately 100 nm to 5 μm.

The additive particles12are formed of any suitable electrically conductive additive. For example, the electrically conductive additive can be a carbon material. The electrically conductive additive is preferably a carbon black material or a carbon nanofiber. The additive particles12have a size of approximately 30 nm to 0.5 μm and a surface area of approximately 5 m2/g to 100 m2/g.

The cathode active material particles14are formed of any suitable cathode active material that is compatible with a solid electrolyte. For example, the cathode active material may be a lithium transition metal oxide such as NMC or lithium cobalt oxide, lithium phosphate, lithium iron phosphate or a mixture thereof. The cathode active material particles14have a diameter of approximately 15 nm to 5 μm.

The cathode4includes at least 80 percent by weight of the cathode active material particles14. The cathode4also includes at least fifteen percent by weight of the catholyte particles10. The cathode4may include up to five percent by weight of the additive particles12. The weight percentage values described above are relative to a total weight of the cathode4.

The cathode4may also optionally contain a binder (not shown). The binder may be any suitable electrode binder material. For example, the binder may include polytetrafluoroethylene, polyvinylidene fluoride, styrene-butadiene rubber, a cellulose material or any combination thereof. The binder is preferably polytetrafluoroethylene. The cathode4has a thickness of approximately 10 μm to 150 μm.

The electrolyte16is any suitable electrolyte for a solid-state battery, such as a solid electrolyte. The solid electrolyte can be any suitable lithium-ion conductive solid electrolyte. For example, the solid electrolyte can be a sulfide-based solid electrolyte, such as Li6PS5Cl, an oxide solid electrolyte, or a hybrid solid electrolyte that includes a sulfide-based solid electrolyte and a polyethylene oxide (“PEO”) based polymer. The electrolyte16has a thickness of approximately 10 μm to 20 μm.

The anode current collector18is formed of any suitable metal material, such as aluminum or copper, preferably copper. The anode current collector18has a thickness ranging from 60 μm to 100 μm, preferably 60 μm.

The second metal support20is formed of any suitable metal material, such as aluminum or copper, preferably aluminum. The second metal support20has a thickness ranging from 60 μm to 100 μm, preferably 60 μm. The second metal support20has a circular shape, but it should be understood that the second metal support20may have any suitable shape, such as a square or rectangular shape.

As shown inFIG.1(b), the first metal support2, the cathode current collector6, the solid electrolyte16, the anode current collector18and the second metal support20are all at least substantially the same after charging, i.e., have the same thickness and shape, as before charging.

However, after charging, the columns8are compressed as shown inFIG.1(b)compared to the columns8before charging as shown inFIG.1(a). In other words, the columns8are shortened while charging and slightly elongated while discharging providing a spring action for the battery assembly, i.e., the electrode/electrolyte.

Although the solid-state battery1is anode-free before charging as shown inFIG.1(a), the anode22is formed during charging such that it is disposed on the top surface of the anode current collector18between the anode current collector18and the solid electrolyte16. The anode22is formed during charging by precipitation of lithium from the intercalated lithium in the cathode active material particles14. Therefore, the anode22is formed entirely of lithium metal or a lithium alloy, such as a lithium-silver alloy. The anode22has a thickness of approximately 20 μm to 40 μm, preferably 30 μm. The increase in thickness or expansion of the solid-state battery1during charging due to formation of the anode22is accommodated by providing the columns8formed of a foam material having a porosity of 80% or more, which are each compressed during formation of the anode22.

FIGS.2(a)-2(c)show a solid-state battery30that includes a cathode32, an electrolyte34and an anode36in accordance with a second embodiment. Like the solid-state battery1of the first embodiment, the solid-state battery30is preferably an all-solid-state battery and can be incorporated in a vehicle, a mobile device, a laptop computer or other suitable personal electronic devices.

As shown inFIGS.2(b) and2(c), the cathode32includes a cathode current collector38, a plurality of columns40formed within and extending from a bottom surface of the cathode current collector38, and a cathode material42that surrounds the columns40so as to form a layer between the cathode current collector38and the electrolyte34. The cathode current collector38is formed of any suitable metal material, such as aluminum or copper, preferably aluminum. The cathode current collector38has a thickness ranging from 60 μm to 100 μm, preferably 60 μm.

As shown inFIG.2(c), the columns40are formed within and extending from cavities44in the bottom surface of the cathode current collector38. The columns40are spaced apart from each other and may be formed in any suitable pattern, as long as the columns40cover approximately 20-30% of the surface area of the cathode current collector38, preferably 25% of the surface area of the cathode current collector38. As shown inFIG.2(c), the columns40are formed in a pie-shaped pattern and do not cover a central area of the bottom surface of the cathode current collector38. However, it should be understood that the columns40may be formed in a circular pattern or any other suitable pattern.

The columns40are formed of a foam material. The foam material may be any suitable foam material that acts as a cushion. For example, the foam material has a porosity of 80% or more, is stable in lithium, and can withstand several cycles without degradation. The foam material is preferably formed of polystyrene, polyurethane, glass wool, or a mixture thereof.

Each of the columns40has a same prescribed diameter and length extending from the cavities44within the bottom surface of the cathode current collector38. In this embodiment, the columns40have a same length and extend throughout the entire thickness of the cathode32such that they are in contact with the electrolyte34. However, it should be understood that the columns40may have any prescribed length that is at least 75% of the total thickness of the cathode32. Furthermore, it should be understood that the columns40may have different lengths extending from the cavities44within the bottom surface of the cathode current collector38, as long as each of the columns40has a prescribed length of at least 75% of the total thickness of the cathode32. Each of the columns40has a prescribed length of 10 μm to 30 μm, preferably 20 μm and a prescribed diameter of approximately 1 μm to 5 μm, preferably 3 μm.

The cavities44are formed in the cathode current collector38in any suitable manner, for example using a laser to perform laser etching. The foam material is then filled in the cavities and grown to form the columns40.

The cathode material42includes catholyte particles, additive particles and cathode active material particles. The catholyte particles are formed of any suitable catholyte material for a solid-state battery. For example, the catholyte material may be any suitable lithium-ion conductive solid electrolyte material. In particular, the catholyte material can be a sulfide-based solid electrolyte, such as Li6PS5Cl, an oxide solid electrolyte, or a hybrid solid electrolyte that includes a sulfide-based solid electrolyte and a polyethylene oxide (“PEO”) based polymer. The catholyte particles have a size ranging from approximately 100 nm to 5 μm.

The additive particles are formed of any suitable electrically conductive additive. For example, the electrically conductive additive can be a carbon material. The electrically conductive additive is preferably a carbon black material or a carbon nanofiber. The additive particles have a size of approximately 30 nm to 0.5 μm and a surface area of approximately 5 m2/g to 100 m2/g.

The cathode active material particles are formed of any suitable cathode active material that is compatible with a solid electrolyte. For example, the cathode active material may be a lithium transition metal oxide such as NMC or lithium cobalt oxide, lithium phosphate, lithium iron phosphate or a mixture thereof. The cathode active material particles have a diameter of approximately 15 nm to 5 μm.

The cathode material42includes at least 80 percent by weight of the cathode active material particles. The cathode material42also includes at least fifteen percent by weight of the catholyte particles. The cathode42may include up to five percent by weight of the additive particles. The weight percentage values described above are relative to a total weight of the cathode material42.

The cathode material42may also optionally contain a binder (not shown). The binder may be any suitable electrode binder material. For example, the binder may include polytetrafluoroethylene, polyvinylidene fluoride, styrene-butadiene rubber, a cellulose material or any combination thereof. The binder is preferably polytetrafluoroethylene. The cathode material42has a thickness of approximately 10 μm to 150 μm.

The electrolyte34is any suitable electrolyte for a solid-state battery, such as a solid electrolyte. The solid electrolyte can be any suitable lithium-ion conductive solid electrolyte. For example, the solid electrolyte can be a sulfide-based solid electrolyte, such as Li6PS5Cl, an oxide solid electrolyte, or a hybrid solid electrolyte that includes a sulfide-based solid electrolyte and a PEO based polymer. The electrolyte34has a thickness of approximately 10 μm to 20 μm.

The anode36includes an anode material and an anode current collector. The anode material includes an anode active material. The anode material may also include a binder and an additive. The anode active material is any suitable anode active material that is compatible with a solid electrolyte. For example, the anode active material is formed of metal, preferably entirely of metal. The anode active material is preferably formed of lithium, sodium, magnesium, or a mixture thereof. For example, the anode active material may be formed of lithium or a lithium alloy.

The anode material may also include an additive and/or a binder. The anode material includes approximately 90-95 percent by weight of the anode active material and five to ten percent by weight of the additive plus the binder. For example, the anode material may include approximately 95.0 percent by weight of the anode active material, 2.5 percent by weight of the additive and 2.5 percent by weight of the binder.

When a sulfide-based solid electrolyte is used as the electrolyte34and the anode material includes lithium metal, a protective layer (not shown) may be also provided between the electrolyte34and the anode36.

The anode current collector is formed of any suitable metal material, such as aluminum or copper, preferably copper. The anode current collector has a thickness ranging from 60 μm to 100 μm, preferably 60 μm.

FIGS.3(a)-3(e)show a solid-state battery50that includes a cathode52, an electrolyte54and an anode56in accordance with a third embodiment. Like the solid-state battery1of the first embodiment and the solid-state battery30of the second embodiment, the solid-state battery50is preferably an all-solid-state battery and can be incorporated in a vehicle, a mobile device, a laptop computer or other suitable personal electronic devices.

As shown inFIGS.3(b) and3(d), the cathode52includes a cathode current collector58, a plurality of columns60formed within and extending from a bottom surface of the cathode current collector58, and a cathode material62that surrounds the columns60so as to form a layer between the cathode current collector58and the electrolyte54. The cathode current collector58is formed of any suitable metal material, such as aluminum or copper, preferably aluminum. The cathode current collector58has a thickness ranging from 60 μm to 100 μm, preferably 60 μm.

As shown inFIG.3(d), the columns60are formed within and extending from cavities64in the bottom surface of the cathode current collector58. The columns60are spaced apart from each other and may be formed in any suitable pattern, as long as the columns60cover approximately 20-30% of the surface area of the cathode current collector58, preferably 25% of the surface area of the cathode current collector58. As shown inFIG.3(d), the columns60are formed in a pie-shaped pattern and do not cover a central area of the bottom surface of the cathode current collector58. However, it should be understood that the columns60may be formed in a circular pattern or any other suitable pattern.

The columns60are formed of a foam material. The foam material may be any suitable foam material that acts as a cushion. For example, the foam material has a porosity of 80% or more, is stable in lithium, and can withstand several cycles without degradation. The foam material is preferably formed of polystyrene, polyurethane, glass wool, or a mixture thereof.

Each of the columns60has a same prescribed diameter and length extending from the cavities64within the bottom surface of the cathode current collector58. In this embodiment, the columns60have a same length and extend throughout the entire thickness of the cathode52such that they are in contact with the electrolyte54. However, it should be understood that the columns60may have any prescribed length that is at least 75% of the total thickness of the cathode52. Furthermore, it should be understood that the columns60may have different lengths extending from the cavities64within the bottom surface of the cathode current collector58, as long as each of the columns60has a prescribed length of at least 75% of the total thickness of the cathode52. Each of the columns60has a prescribed length of 10 μm to 30 μm, preferably 20 μm and a prescribed diameter of approximately 1 μm to 5 μm, preferably 3 μm.

The cavities64are formed in the cathode current collector58in any suitable manner, for example using a laser to perform laser etching. The foam material is then filled in the cavities and grown to form the columns60.

The cathode material62includes catholyte particles, additive particles and cathode active material particles. The catholyte particles are formed of any suitable catholyte material for a solid-state battery, such as a lithium-ion conductive solid electrolyte material. In particular, the catholyte material can be a sulfide-based solid electrolyte, such as Li6PS5Cl, an oxide solid electrolyte, or a hybrid solid electrolyte that includes a sulfide-based solid electrolyte and a polyethylene oxide (“PEO”) based polymer. The catholyte particles have a size ranging from approximately 100 nm to 5 μm.

The additive particles are formed of any suitable electrically conductive additive. For example, the electrically conductive additive can be a carbon material. The electrically conductive additive is preferably a carbon black material or a carbon nanofiber. The additive particles have a size of approximately 30 nm to 0.5 μm and a surface area of approximately 5 m2/g to 100 m2/g.

The cathode active material particles are formed of any suitable cathode active material that is compatible with a solid electrolyte. For example, the cathode active material may be a lithium transition metal oxide such as NMC or lithium cobalt oxide, lithium phosphate, lithium iron phosphate or a mixture thereof. The cathode active material particles have a diameter of approximately 15 nm to 5 μm.

The cathode material62includes at least 80 percent by weight of the cathode active material particles. The cathode material62also includes at least fifteen percent by weight of the catholyte particles. The cathode62may include up to five percent by weight of the additive particles. The weight percentage values described above are relative to a total weight of the cathode material62.

The cathode material62may also optionally contain a binder (not shown). The binder may be any suitable electrode binder material. For example, the binder may include polytetrafluoroethylene (“PTFE”), polyvinylidene fluoride (“PVDF”), styrene-butadiene rubber (“SBR”), a cellulose material or any combination thereof. The binder is preferably PTFE. The cathode material42has a thickness of approximately 10 μm to 150 μm.

The electrolyte54is any suitable electrolyte for a solid-state battery, such as a solid electrolyte. The solid electrolyte can be any suitable lithium-ion conductive solid electrolyte. For example, the solid electrolyte can be a sulfide-based solid electrolyte, such as Li6PS5Cl, an oxide solid electrolyte, or a hybrid solid electrolyte that includes a sulfide-based solid electrolyte and a PEO based polymer. The electrolyte54has a thickness of approximately 10 μm to 20 μm.

As shown inFIGS.3(c) and3(e), the anode56includes an anode current collector66, a plurality of columns68formed within and extending from a top surface of the anode current collector66, and an anode material70that surrounds the columns68so as to form a layer between the anode current collector66and the electrolyte54. The anode current collector66is formed of any suitable metal material, such as aluminum or copper, preferably copper. The anode current collector66has a thickness ranging from 60 μm to 100 μm, preferably 60 μm.

As shown inFIG.3(e), the columns68are formed within and extending from cavities72in the top surface of the anode current collector66. The columns68are spaced apart from each other and may be formed in any suitable pattern, as long as the columns68cover approximately 20-30% of the surface area of the anode current collector66, preferably 25% of the surface area of the anode current collector66. As shown inFIG.3(e), the columns68are formed in a pie-shaped pattern and do not cover a central area of the top surface of the anode current collector66. However, it should be understood that the columns68may be formed in a circular pattern or any other suitable pattern.

The columns68are formed of a foam material. The foam material may be any suitable foam material that acts as a cushion. For example, the foam material has a porosity of 80% or more, is stable in lithium, and can withstand several cycles without degradation. The foam material is preferably formed of polystyrene, polyurethane, glass wool, or a mixture thereof.

Each of the columns68has a same prescribed diameter and length extending from the cavities72within the top surface of the anode current collector66. In this embodiment, the columns68have a same length and extend throughout the entire thickness of the anode56such that they are in contact with the electrolyte54. However, it should be understood that the columns68may have any prescribed length that is at least 75% of the total thickness of the anode56. Furthermore, it should be understood that the columns68may have different lengths extending from the cavities72within the top surface of the anode current collector66, as long as each of the columns68has a prescribed length of at least 75% of the total thickness of the anode56. Each of the columns68has a prescribed length of 10 μm to 30 μm, preferably 20 μm and a prescribed diameter of approximately 1 μm to 5 μm, preferably 3 μm.

The cavities72are formed in the anode current collector66in any suitable manner, for example using a laser to perform laser etching. The foam material is then filled in the cavities and grown to form the columns68.

The anode material70includes an anode active material. The anode material70may also optionally include a binder and an additive. The anode active material is a carbon-based anode active material that is compatible with a solid electrolyte. For example, the anode active material is formed of graphite or nanocarbon. The anode material70includes approximately 90-95 percent by weight of the anode active material and five to ten percent by weight of any additive plus any binder. The anode material70has a thickness of approximately 20 μm to 40 μm, preferably 30 μm.

The additive is any suitable electrically conductive additive. For example, the additive can be a carbon material, preferably a carbon black material or a carbon nanofiber having a surface area of approximately 5 m2/g to 100 m2/g. The binder may be any suitable electrode binder material. For example, the binder may include PTFE, PVDF, SBR, a cellulose material or any combination thereof. The binder is preferably PVDF.

FIG.4(a)shows an electrode80for a solid-state battery at a first time in accordance with a fourth embodiment. The electrode80includes a current collector82, a plurality of cavities84formed in the surface of the current collector82, and a foam material86formed in the cavities84of the current collector82. The electrode80can be used as a cathode or an anode in a solid-state battery, and the solid-state battery can be incorporated in a vehicle, a mobile device, a laptop computer or other suitable personal electronic device.

The current collector82is formed of any suitable metal material, such as aluminum or copper. The current collector82has a thickness ranging from 60 μm to 100 μm, preferably 60 μm.

The cavities84are formed in the current collector82in any suitable manner, for example using a laser to perform laser etching. The cavities84have a diameter or size of approximately 1 μm to 5 μm, preferably 3 μm, and a depth of approximately 5 μm to 15 μm, preferably 10 μm.

The cavities84are filled with a foam material precursor86. The foam material precursor86may be any suitable precursor to form a foam material that acts as a cushion. For example, the foam material precursor may be a polyol.

As shown inFIG.4(b), the current collector82and the cavities84are at least substantially the same, i.e., have the same thickness and shape, at a second, later time, as at the first time shown inFIG.4(a).

However, at the second time, a polyisocyanate material is applied to the foam material precursor86to form columns88of a foam material having a first height extending from the surface of the current collector82. The polyisocyanate material reacts with the foam material precursor86to form the foam material of the columns88. The foam material of the columns88has a porosity of at least 80% and is preferably a polyurethane material.

Referring now toFIG.4(c), the current collector82and the cavities84are at least substantially the same, i.e., have the same thickness and shape, at a third time that is later than the second time. However, at the third time, after the polyisocyanate material has reacted with the foam material precursor material86to form the columns88, the columns88are grown to a second height that is greater than the first height extending from the surface of the current collector82. The second height is 10 μm to 30 μm, preferably 20 μm. This change in the columns88after application of the polyisocyanate is due to growth of the foam material after reaction of the polyisocyanate and the polyol. The columns88have a diameter of approximately 1 μm to 5 μm, preferably 3 μm.

The volume changes in the solid-state battery can be reduced because the columns88formed of the foam material absorb pressure increases during charging and discharging and act as springs that can contract under pressure, for example during charging, and can re-expand when the pressure is reduced, for example during discharging. The foam material has a porosity of at least 80% and is stable in lithium.

FIG.5illustrates a process100of forming a solid-state battery including an electrode with a dimension retainer according to a fifth embodiment. In Step102, a pattern is made in a cathode current collector. The cathode current collector is formed of aluminum. However, it should be understood that the cathode current collector may be formed of any suitable metal material, such as aluminum or copper. The cathode current collector has a thickness ranging from 60 μm to 100 μm, preferably 60 μm.

In Step102, the pattern is formed in the cathode current collector using a laser or stamping method to form a plurality of cavities in the desired pattern in a surface of the cathode current collector. The pattern may be any suitable pattern, as long as the cavities cover approximately 20-30% of the surface area of the cathode current collector, preferably 25% of the surface area of the cathode current collector. The cavities are preferably formed in a pie-shaped pattern and do not cover a central area of the cathode current collector However, it should be understood that the cavities may be formed in a circular pattern or any other suitable pattern.

The pattern is formed such that each of the cavities has a same prescribed depth from the surface of the cathode current collector. For example, each of the cavities is formed to have a prescribed depth of approximately 5 μm to 15 μm, preferably 10 μm. However, it should be understood that the cavities may have different depths from the surface of the cathode current collector.

In Step104, a polyol precursor is applied or filled in the cavities of the cathode current collector. The polyol precursor may be any suitable polyol material that can be used to form a foam material.

In Step106, the polyol precursor is grown to columns formed of a foam material using polyisocyanate. In particular, polyisocyanate is applied to the polyol precursor in the cavities of the cathode current collector, and the polyisocyanate reacts with the polyol precursor to form polyurethane. The polyurethane has a porosity of 80% or more. However, it should be understood that any suitable material may be applied in this step, as long as the material reacts with the polyol precursor to form a foam material having a porosity of at least 80%. The columns have a height of 10 μm to 30 μm, preferably 20 μm, and a diameter of approximately 1 μm to 5 μm, preferably 3 μm. The columns have a cylindrical or tubular shape, but it should be understood that the columns may have any suitable shape that gives a cushion or spring effect when the solid-state battery is under pressure.

In Step108, a composite cathode material is grown on the surface of the cathode current collector having the columns to form a cathode. For example, the composite cathode material may be applied to the surface of the current collector such that the composite cathode material completely surrounds the columns and the cathode material has a thickness that is the same as the height of the columns extending from the surface of the cathode current collector. The composite cathode material includes a cathode active material. The cathode active material is any suitable cathode active material that is compatible with a solid electrolyte. For example, the cathode active material may be a lithium transition metal oxide such as NMC or lithium cobalt oxide, lithium phosphate, lithium iron phosphate or a mixture thereof.

The composite cathode material also includes catholyte particles, an additive and optionally a binder. For example, the cathode material may have a same composition as the cathode material42of the second embodiment or the cathode material62of the third embodiment. For example, the cathode material includes at least 80 percent by weight of the cathode active material and at least fifteen percent by weight of the catholyte particles. The cathode material also includes up to five percent by weight of the additive plus the binder. For example, the cathode material may include approximately two percent by weight of the additive and approximately three percent by weight of the binder. The weight percentage values described above are relative to a total weight of the cathode material.

In Step110, a solid electrolyte is applied to the cathode such that the solid electrolyte is in contact with both the composite cathode material and the columns of foam material. The solid electrolyte can be any suitable lithium-ion conductive solid electrolyte. For example, the solid electrolyte can be a sulfide-based solid electrolyte, such as Li6PS5Cl, an oxide solid electrolyte, or a hybrid solid electrolyte that includes a sulfide-based solid electrolyte and a PEO based polymer. The solid electrolyte is formed to have a thickness of approximately 10 μm to 20 μm.

In Step112, the cathode and solid electrolyte are assembled with an anode-coated current collector to form the solid-state battery. In particular, the anode-coated current collector is assembled such that the electrolyte is disposed between the cathode and the anode-coated current collector. The anode-coated current collector includes an anode current collector coated with an anode material.

The anode current collector is formed of copper. However, it should be understood that the anode current collector may be formed of any suitable metal material, such as aluminum or copper. The anode current collector has a thickness ranging from 60 μm to 100 μm, preferably 60 μm.

The anode material includes an anode active material. The anode material may also optionally include a binder and an additive. The anode active material is a carbon-based anode active material that is compatible with a solid electrolyte. For example, the anode active material is formed of graphite or nanocarbon. Alternatively, the anode active material is formed of metal, preferably entirely of metal, such as lithium, sodium, magnesium, or a mixture thereof. For example, the anode active material may be lithium or a lithium alloy. The anode active material may also be a silicon-based anode active material. The anode material includes approximately 90-95 percent by weight of the anode active material and five to ten percent by weight of any additive plus any binder. The anode material has a thickness of approximately 20 μm to 40 μm, preferably 30 μm.

The additive is any suitable electrically conductive additive. For example, the additive can be a carbon material, preferably a carbon black material or a carbon nanofiber having a surface area of approximately 5 m2/g to 100 m2/g. The binder may be any suitable electrode binder material. For example, the binder may include PTFE, PVDF, SBR, a cellulose material or any combination thereof. The binder is preferably PVDF.

Like the solid-state battery of the first, second and third embodiments, the solid-state battery of this embodiment is preferably an all-solid-state battery and can be incorporated in a vehicle, a mobile device, a laptop computer or other suitable personal electronic devices.

FIG.6illustrates a process200of forming a solid-state battery including an electrode with a dimension retainer according to a sixth embodiment. In Step102, a pattern is made in an anode current collector The anode current collector is formed of copper. However, it should be understood that the anode current collector may be formed of any suitable metal material, such as aluminum or copper. The anode current collector has a thickness ranging from 60 μm to 100 μm, preferably 60 μm.

In Step202, the pattern is formed in the cathode current collector using a laser or stamping method to form a plurality of cavities in the desired pattern in a surface of the anode current collector. The pattern may be any suitable pattern, as long as the cavities cover approximately 20-30% of the surface area of the anode current collector, preferably 25% of the surface area of the anode current collector. The cavities are preferably formed in a pie-shaped pattern and do not cover a central area of the anode current collector. However, it should be understood that the cavities may be formed in a circular pattern or any other suitable pattern.

The pattern is formed such that each of the cavities has a same prescribed depth from the surface of the anode current collector. For example, each of the cavities is formed to have a prescribed depth of approximately 5 μm to 15 μm, preferably 10 μm. However, it should be understood that the cavities may have different depths from the surface of the anode current collector.

In Step204, a polyol precursor is applied or filled in the cavities of the anode current collector. The polyol precursor may be any suitable polyol material that can be used to form a foam material.

In Step206, the polyol precursor is grown to columns formed of a foam material using polyisocyanate. In particular, polyisocyanate is applied to the polyol precursor in the cavities of the cathode current collector, and the polyisocyanate reacts with the polyol precursor to form polyurethane. The polyurethane has a porosity of 80% or more. However, it should be understood that any suitable material may be applied in this step, as long as the material reacts with the polyol precursor to form a foam material having a porosity of at least 80%. The columns have a height of 10 μm to 30 μm, preferably 20 μm, and a diameter of approximately 1 μm to 5 μm, preferably 3 μm. The columns have a cylindrical or tubular shape, but it should be understood that the columns may have any suitable shape that gives a cushion or spring effect when the solid-state battery is under pressure.

In Step208, an anode material is formed on the surface of the anode current collector having the columns to form an anode. For example, the anode material may be applied to the surface of the current collector such that the anode material completely surrounds the columns and the anode material has a thickness that is the same as the height of the columns extending from the surface of the anode current collector.

The anode material includes an anode active material and optionally an additive and/or a binder. The anode active material is a carbon-based anode active material that is compatible with a solid electrolyte. For example, the anode active material is formed of graphite or nanocarbon. The anode material includes approximately 90-95 percent by weight of the anode active material and five to ten percent by weight of any additive plus any binder. The anode material has a thickness of approximately 20 μm to 40 μm, preferably 30 μm.

The additive is any suitable electrically conductive additive. For example, the additive can be a carbon material, preferably a carbon black material or a carbon nanofiber having a surface area of approximately 5 m2/g to 100 m2/g. The binder may be any suitable electrode binder material. For example, the binder may include PTFE, PVDF, SBR, a cellulose material or any combination thereof. The binder is preferably PVDF.

In Step210, a solid electrolyte is applied to the anode such that the solid electrolyte is in contact with both the anode material and the columns of foam material. The solid electrolyte can be any suitable lithium-ion conductive solid electrolyte. For example, the solid electrolyte can be a sulfide-based solid electrolyte, such as Li6PS5Cl, an oxide solid electrolyte, or a hybrid solid electrolyte that includes a sulfide-based solid electrolyte and a PEO based polymer. The solid electrolyte is formed to have a thickness of approximately 10 μm to 20 μm.

In Step212, the anode and solid electrolyte are assembled with a cathode-coated current collector to form the solid-state battery. In particular, the cathode-coated current collector is assembled such that the electrolyte is disposed between the anode and the cathode-coated current collector. The cathode-coated current collector includes a cathode current collector coated with a cathode material.

The cathode current collector is formed of aluminum. However, it should be understood that the cathode current collector may be formed of any suitable metal material, such as aluminum or copper. The cathode current collector has a thickness ranging from 60 μm to 100 μm, preferably 60 μm.

The cathode material includes a cathode active material that is compatible with a solid electrolyte. For example, the cathode active material may be a lithium transition metal oxide such as NMC or lithium cobalt oxide, lithium phosphate, lithium iron phosphate or a mixture thereof.

The cathode material also includes catholyte particles, an additive and optionally a binder. For example, the cathode material may have a same composition as the cathode material42of the second embodiment or the cathode material62of the third embodiment. For example, the cathode material includes at least 80 percent by weight of the cathode active material and at least fifteen percent by weight of the catholyte particles. The cathode material also includes up to five percent by weight of the additive plus the binder. For example, the cathode material may include approximately two percent by weight of the additive and approximately three percent by weight of the binder. The weight percentage values described above are relative to a total weight of the cathode material.

Like the solid-state battery of the first, second, third and fifth embodiments, the solid-state battery of this embodiment is preferably an all-solid-state battery and can be incorporated in a vehicle, a mobile device, a laptop computer or other suitable personal electronic devices.

FIG.7(a)shows an electrode300for a solid-state battery in accordance with a seventh embodiment. The electrode300includes a current collector302, a plurality of hollow columns304formed within and extending from a surface of the current collector302, and an electrode active material306formed within the hollow columns304. The electrode300can be used as a cathode or an anode in a solid-state battery, and the solid-state battery can be incorporated in a vehicle, a mobile device, a laptop computer or other suitable personal electronic device. The electrode300is preferably a cathode.

The current collector302is formed of any suitable metal material, such as aluminum or copper. The current collector302is preferably a cathode current collector formed of aluminum. The current collector302has a thickness ranging from 60 μm to 100 μm, preferably 60 μm.

The columns304are formed within and extending from the surface of the current collector302. The columns304are hollow and are spaced apart from each other and formed in any suitable pattern, as long as the columns304cover approximately 20-30% of the surface area of the current collector302, preferably 25% of the surface area of the current collector302. The columns304are preferably formed in a pattern such that they do not cover a central area of the surface of the current collector302. The columns304are also preferably formed in a pie-shaped pattern or a circular pattern.

Each of the hollow columns304has a same prescribed diameter and length extending from a first end within the surface of the current collector302to an opposite end. Preferably, each of the hollow columns304has a same prescribed length of 10 μm to 30 μm, preferably 20 μm, and a prescribed diameter of approximately 1 μm to 5 μm, preferably 3 μm. However, it should be understood that the hollow columns304may have different diameters and different lengths extending from the first end within the surface of the current collector302to the opposite end, as long as each of the columns304has a prescribed length of 10 μm to 30 μm, preferably 20 μm, and a prescribed diameter of approximately 1 μm to 5 μm, preferably 3 μm.

The hollow columns304are formed of a foam material. The foam material may be any suitable foam material that acts as a cushion. For example, the foam material has a porosity of 80% or more, is stable in lithium, and can withstand several cycles without degradation. The foam material is preferably formed of polystyrene, polyurethane, glass wool, or a mixture thereof.

The columns304may be formed in the current collector302in any suitable manner, for example using a laser to perform laser etching and form cavities in the current collector302and filling the cavities with the foam material or a precursor for the foam material.

The electrode active material306is formed of any suitable electrode active material that is compatible with a solid electrolyte. Preferably, the electrode active material306is a cathode active material, for example a lithium transition metal oxide such as NMC or lithium cobalt oxide, lithium phosphate, lithium iron phosphate or a mixture thereof.

As shown inFIG.7(b), the electrode active material306is filled in the hollow columns304. In particular, the electrode active material306is filled in the hollow columns304such that the electrode active material306has a width of approximately 0.5 μm to 1.5 μm, preferably 1 μm, within each of the hollow columns304.

The volume changes in the solid-state battery can be reduced because the columns304formed of the foam material absorb pressure increases during charging and discharging and act as springs that can contract under pressure, for example during charging, and can re-expand when the pressure is reduced, for example during discharging.

GENERAL INTERPRETATION OF TERMS

The terms of degree, such as “approximately” or “substantially” as used herein, mean a reasonable amount of deviation of the modified term such that the end result is not significantly changed.