PATENT DOCUMENT

Publication Number: US-10868290-B2
Application Number: US-201615384764-A
Country: US
Kind Code: B2

Title: Lithium-metal batteries having improved dimensional stability and methods of manufacture

Abstract:
Lithium-metal batteries with improved dimensional stability are presented along with methods of manufacture. The lithium-metal batteries incorporate an anode cell that reduces dimensional changes during charging and discharging. The anode cell includes a container having a first portion and a second portion to form an enclosed cavity. The first portion is electrically-conductive and chemically-stable to lithium metal. The second portion is permeable to lithium ions and chemically-stable to lithium metal. The anode cell also includes an anode comprising lithium metal and disposed within the cavity. The anode is in contact with the first portion and the second portion. The cavity is configured such that volumetric expansion and contraction of the anode during charging and discharging is accommodated entirely therein.

Claims:
What is claimed is: 
     
       1. An anode cell for a lithium-metal battery, the anode cell comprising:
 a container having a first portion and a second portion to form an enclosed cavity, the first portion electrically-conductive and chemically-stable to lithium metal, the second portion permeable to lithium ions and chemically-stable to lithium metal; 
 an anode comprising lithium metal and disposed within the enclosed cavity, the anode in contact with the first portion and the second portion;
 wherein the enclosed cavity is configured such that volumetric expansion and contraction of the anode during charging and discharging is accommodated entirely therein; 
 wherein a volume of the enclosed cavity is larger in size than a volume of the anode disposed therein; 
 wherein the second portion separates the anode from an electrolyte disposed external to the enclosed cavity; 
 wherein the electrolyte comprises a lithium salt; and 
 wherein the second portion directly contacts the anode. 
 
 
     
     
       2. The anode cell of  claim 1 , wherein the second portion comprises a lid for the first portion. 
     
     
       3. The anode cell of  claim 1 , wherein the second portion comprises a multilayer stack. 
     
     
       4. The anode cell of  claim 1 , wherein the enclosed cavity has a cross-sectional area that is constant along a longitudinal axis thereof. 
     
     
       5. The anode cell of  claim 4 , wherein the enclosed cavity comprises an orifice having a perimeter that defines the cross-sectional area. 
     
     
       6. The anode cell of  claim 5 , further comprising a permeable membrane disposed along an exterior surface of the second portion and opposite the orifice. 
     
     
       7. The anode cell of  claim 5 , wherein the second portion is coupled to the first portion via a seal around the perimeter of the orifice. 
     
     
       8. A battery pack, comprising:
 at least one lithium-metal battery having an anode cell electrochemically coupled to a cathode cell, the anode cell comprising:
 a container having a first portion and a second portion to form an enclosed cavity, the first portion electrically-conductive and chemically-stable to lithium metal, the second portion permeable to lithium ions and chemically-stable to lithium metal, 
 an anode comprising lithium metal and disposed within the enclosed cavity, the anode in contact with the first portion and the second portion,
 wherein the enclosed cavity is configured such that volumetric expansion and contraction of the anode during charging and discharging is accommodated entirely therein; 
 wherein a volume of the enclosed cavity is larger in size than a volume of the anode disposed therein; 
 wherein the second portion separates the anode from an electrolyte disposed external to the enclosed cavity; 
 wherein the electrolyte comprises a lithium salt; and 
 wherein the second portion directly contacts the anode. 
 
 
 
     
     
       9. The battery pack of  claim 8 ,
 wherein the enclosed cavity comprises an orifice having a perimeter; and 
 wherein the anode cell further comprises a permeable membrane disposed along an exterior surface of the second portion and opposite the orifice. 
 
     
     
       10. The battery pack of  claim 9 , wherein the second portion of the container is coupled to the first portion of the container via a seal around the perimeter of the orifice. 
     
     
       11. The battery pack of  claim 9 , wherein the cathode cell comprises:
 a cathode active material in contact with the permeable membrane along an area opposite the orifice; 
 an electrolyte comprising at least one solvated lithium species; and 
 a cathode current collector in contact with the cathode active material. 
 
     
     
       12. The battery pack of  claim 8 ,
 wherein the at least one lithium-metal battery comprises a plurality of lithium-metal batteries arranged in a stacked sequence; and 
 wherein the stacked sequence alternates between a first junction formed by adjacent pairs of anode cells and a second junction formed by adjacent pairs of cathode cells. 
 
     
     
       13. The battery pack of  claim 12 ,
 wherein the at least one lithium-metal battery comprises the plurality of lithium-metal batteries arranged in the stacked sequence; and 
 wherein individual lithium-metal batteries within the stacked sequence have aligned polarities. 
 
     
     
       14. The battery pack of  claim 8 ,
 wherein the at least one lithium-metal battery comprises an array of lithium-metal batteries; and 
 wherein the first portion of the container for each lithium-metal battery defines a section of an extended first portion shared in common. 
 
     
     
       15. The anode cell of  claim 1 , wherein the lithium salt comprises at least one of LiPF 6 , LiBF 4 , LiClO 4 , LiSO 3 CF 3 , LiN(SO 2 CF 3 ) 2 , LiBC 4 O 8 , Li[PF 3 (C 2 CF 5 ) 3 ], and LiC(SO 2 CF 3 ) 3 . 
     
     
       16. The anode cell of  claim 1 , wherein the second portion comprises at least one of a lithium phosphorus oxynitride material, a lithium boron oxynitride material, a lithium boron oxide material, a lithium niobium oxide material, a lithium lanthanum zirconium oxide material, a lithium phosphorus sulfide material, a lithium tin sulfide material, and a lithium germanium phosphorus sulfide material. 
     
     
       17. The battery pack of  claim 8 , wherein the lithium salt comprises at least one of LiPF 6 , LiBF 4 , LiClO 4 , LiSO 3 CF 3 , LiN(SO 2 CF 3 ) 2 , LiBC 4 O 8 , Li[PF 3 (C 2 CF 5 ) 3 ], and LiC(SO 2 CF 3 ) 3 . 
     
     
       18. The battery pack of  claim 8 , wherein the second portion comprises at least one of a lithium phosphorus oxynitride material, a lithium boron oxynitride material, a lithium boron oxide material, a lithium niobium oxide material, a lithium lanthanum zirconium oxide material, a lithium phosphorus sulfide material, a lithium tin sulfide material, and a lithium germanium phosphorus sulfide material.

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
     The present application claims the benefit under 35 U.S.C. § 119(e) of U.S. Provisional Appl. No. 62/300,279, entitled “Lithium-Metal Batteries Having Improved Dimensional Stability and Methods of Manufacture,” filed on Feb. 26, 2016, which is incorporated herein by reference in its entirety. 
    
    
     FIELD 
     This disclosure relates generally to lithium-metal batteries, and more particularly, to anode cells that allow for improved dimensional stability of lithium-metal batteries. 
     BACKGROUND 
     During operation, lithium-metal batteries often undergo cycling processes, which include charging and discharging. During charging, an anode of a lithium-metal battery is continuously plated with lithium metal. During discharging, the anode is continuously stripped of lithium metal. The anode experiences volumetric expansion and contraction in response to, respectively, plating and stripping of lithium metal. Such volumetric expansion and contraction produces undesirable dimensional changes within an anode cell. These dimensional changes are typically concomitant with material stresses, which may reduce the performance of the lithium-metal battery or cause premature failure. 
     Lithium-metal batteries may sometimes be arranged in a stacked sequence. In the stacked sequence, however, volumetric expansion and contraction occurs cumulatively: each lithium-metal battery contributes in additive fashion to a larger, effective dimensional change. This larger, effective dimensional change typically requires void space to be reserved within a target application (e.g., a battery package or a battery-powered apparatus). Reserved void space represents an undesirable loss of functional volume within the target application. 
     The battery industry seeks lithium-metal batteries that have improved dimensional stability. 
     SUMMARY 
     The embodiments described herein relate to lithium-metal batteries having anode cells for reducing dimensional changes during battery cycling. Each anode cell provides an enclosed cavity that contains an anode comprising lithium metal. The enclosed cavity is capable of accommodating all expansion and contraction volumes of the anode during charging and discharging. Each anode cell also includes a solid-state lithium ion conductor that defines a portion of the enclosed cavity (e.g., a lid). Via the portion, the anode cell is coupled electrochemically to a cathode cell to form a lithium-metal battery. In this coupled configuration, the anode cell separates the anode from an electrolyte allowing useful formulations of the electrolyte that would otherwise react with the anode. Such separation may also prevent a formation of lithium-metal dendrites, which can traverse the electrolyte to form a short-circuit pathway between the anode cell and the cathode cell. 
     In various lithium-metal batteries, the anode cell includes a container having a first portion and a second portion to form an enclosed cavity. In some variations, the second portion forms one side of the enclosed cavity. The first portion is electrically-conductive and chemically-stable to lithium metal. The second portion is permeable to lithium ions and chemically-stable to lithium metal. The anode cell also includes an anode comprising lithium metal and disposed within the cavity. The anode is in contact with the first portion and the second portion. The cavity is configured such that volumetric expansion and contraction of the anode during charging and discharging is accommodated entirely therein. 
     The lithium-metal batteries described herein may also be incorporated into battery packs. These battery packs include at least one lithium-metal battery having an anode cell electrochemically-coupled to a cathode cell. The anode cell is as described previously and the cathode cell may be any cathode cell that utilizes lithium ions as a basis for electrochemical operation. In some embodiments, the at least one lithium-metal battery includes a plurality of lithium-metal batteries arranged in a stacked sequence. The stacked sequence alternates between a first junction formed by adjacent pairs of anode cells and a second junction formed by adjacent pairs of cathode cells. In other embodiments, the at least one lithium-metal battery includes an array of lithium-metal batteries. In these embodiments, the first portion of the container for each lithium-metal battery defines a section of an extended first portion shared in common. Other arrangements of the least one lithium-metal are described for battery packs. 
     The lithium-metal batteries may be manufactured using a method that includes the step of depositing a seed layer of lithium metal onto a surface of a substrate. The seed layer covers a predetermined area of the surface, which matches an orifice of a cavity within an electrically-conductive container. The substrate includes a solid-state lithium-ion conductor. The method also includes the step of coupling the electrically-conductive container to the substrate so as to enclose the seed layer within the cavity. Such enclosure includes the seed layer being seated within a perimeter of the orifice. The seed layer is in contact with the electrically-conductive container. Other methods of manufacturing the lithium-metal batteries are described. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The disclosure will be readily understood by the following detailed description in conjunction with the accompanying drawings, wherein like reference numerals designate like structural elements, and in which: 
         FIG. 1A  is a cross-sectional view of a lithium-metal battery, during a charging process, with an anode cell for reducing dimensional changes during battery cycling, according to an illustrative embodiment. 
         FIG. 1B  is a cross-sectional view of the lithium-metal battery of  FIG. 1A , but during a discharging process, according to an illustrative embodiment. 
         FIG. 1C  is a cross-sectional view of the lithium-metal battery of  FIG. 1C , but in which the second portion includes a multilayer stack, according to an illustrative embodiment. 
         FIG. 2A  is a schematic diagram of a plurality of lithium-metal batteries arranged in a stacked sequence, according to an illustrative embodiment. 
         FIG. 2B  is a schematic diagram of the stacked sequence of  FIG. 2A , but in which the stacked sequence is electrically coupled in parallel, according to an illustrative embodiment. 
         FIG. 2C  is a schematic diagram of the stacked sequence of  FIG. 2A , but in which the stacked sequence is electrically coupled in series, according to an illustrative embodiment. 
         FIG. 2D  is a schematic diagram of the stacked sequence of  FIG. 2A , but in which the stacked sequence includes lithium-metal batteries having aligned polarities, according to an illustrative embodiment. 
         FIG. 3  is a perspective view of part of an extended first portion having cavities with corresponding orifices on a common side, according to an illustrative embodiment. 
         FIG. 4  is a perspective view of part of an extended first portion having a first planar array of cavities opposite a second planar array of cavities, according to an illustrative embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made in detail to representative embodiments illustrated in the accompanying drawings. It should be understood that the following descriptions are not intended to limit the embodiments to one preferred embodiment. To the contrary, it is intended to cover alternatives, modifications, and equivalents as can be included within the spirit and scope of the described embodiments as defined by the appended claims. 
     Now referring to  FIGS. 1A &amp; 1B , a cross-sectional view is presented of a lithium-metal battery  100  having an anode cell  102  for reducing dimensional changes during battery cycling, according to an illustrative embodiment.  FIG. 1A  corresponds to the lithium-metal battery  100  during a charging process and  FIG. 1B  corresponds to the lithium-metal battery  100  during a discharging process. In some embodiments, such as that shown in  FIGS. 1A &amp; 1B , an electrically-conductive portion of the anode cell  102  functions as an anode current collector for the lithium-metal battery  100 . In other embodiments, the anode cell  102  is electrically-coupled to an anode current collector. 
     The anode cell  102  includes a container  104  having a first portion  106  and a second portion  108  to form an enclosed cavity  110 . In the embodiment of  FIGS. 1A and 1B , the second portion  108  forms a single wall of the enclosed cavity  110 , and the first portion  106  forms the other walls. The first portion  106  is electrically-conductive and chemically-stable to lithium metal. The second portion  108  is permeable to lithium ions and chemically-stable to lithium metal. In some embodiments, the second portion  108  includes a lid (or serves as a lid) for the first portion  106 . In some embodiments, such as that depicted in  FIG. 1C , the second portion  108  includes a multilayer stack. In these embodiments, materials of the multilayer stack and their arrangement may be chosen so as to avoid a dendritic growth of lithium metal through the second portion  108 . 
     The anode cell  102  also includes an anode  112  comprising lithium metal and disposed within the enclosed cavity  110 . The anode  112  is in contact with the first portion  106  and the second portion  108 . Such contact allows a flow of electrons (i.e., via the first portion  104 ) and a mass transport of lithium ions (i.e., via the second portion  108 ) during operation. The enclosed cavity  110  is configured such that volumetric expansion and contraction of the anode  112  during charging and discharging is accommodated entirely therein. 
     The first portion  106  of the container  104  may be formed of electrically-conductive material that is non-reactive towards lithium metal, such as Cu, Ni, Fe, Co, Mn, Cr, V, Mo, W, Nb, and Ta. Alternatively, the first portion  106  may be formed of electrically-conductive material having one or more protective coatings that are non-reactive towards lithium metal. Such protective coatings may themselves be conductive or be applied in areas so that an overall electrical conductivity of the first portion  106  is maintained. Other types of composite configurations are possible for the first portion  106 . 
     The enclosed cavity  110  may exhibit various geometries such as cylindrical volumes, rectangular volumes, and hemispherical volumes. Non-symmetrical volumes can also be used. In some embodiments, the enclosed cavity  110  has a cross-sectional area that is constant along its longitudinal axis  114 . In some embodiments, the enclosed cavity  110  includes an orifice  116  having a perimeter  118  that defines the cross-sectional area of the enclosed cavity  110 . In some embodiments, such as that shown in  FIGS. 1A &amp; 1B , the cross-sectional area is constant along its longitudinal axis  114  and is defined by the perimeter  118  of the orifice  116 . 
     As depicted in  FIGS. 1A &amp; 1B , the first portion  106  has two enclosed cavities  110  arranged in a “back-to-back” configuration. The corresponding orifices  116  face in opposite directions. However, this depiction is not intended as limiting. The first portion  106  may have any number of enclosed cavities  110  arranged in any type of configuration. The orifices  116  may face any direction. For example, and without limitation, the orifices  116  may be canted relative to each other to form patterns (e.g., peaks, valleys, clusters, etc.). In another non-limiting example, the orifices  116  may be grouped into rows, each row tilted such that orifices  116  therein face a common direction. It will be appreciated that, for a plurality of enclosed cavities  110 , the corresponding volumes may be different in geometry, scale, or any combination thereof. 
     The second portion  108  may form a single body with the first portion  106 , or as shown in  FIGS. 1A &amp; 1B , be coupled to the first portion  106  as a second body. In some embodiments, the second portion  108  is coupled to the first portion  106  via a seal  120  around the perimeter  118  of the orifice  116 . The seal  120  protects a volume within the enclosed cavity  110  by excluding contaminants from an environment of the anode cell  102  (e.g., an electrolyte). The seal  120  may include a bonding compound that is chemically-stable with respect to lithium metal, the first portion  106 , and the second portion  108 . In some embodiments, the seal  120  includes a copolymer of ethylene and methacrylic acid. The copolymer may incorporate metal ions such as zinc, sodium, lithium, and potassium. Other additives are possible for the copolymer. 
     In some embodiments, the second portion  108  may include a solid-state lithium-ion conductor. Non-limiting examples of the solid-state lithium-ion conductor include a lithium phosphorus oxynitride material (e.g., LiPON), a lithium boron oxynitride material (e.g., LiBON), a lithium boron oxide material (e.g., LiBO 3 ), a lithium niobium oxide material (e.g., LiNbO 3 ), a lithium lanthanum zirconium oxide material (e.g., Li 7 La 3 Zr 2 O 12 ), a lithium phosphorus sulfide material (e.g., Li 3 PS 4 ), a lithium tin sulfide material (e.g., Li 4 SnS 4 ), and a lithium germanium phosphorus sulfide material (e.g., Li 10 GeP 2 S 12 ). Other solid-state lithium-ion conductors are possible. In further embodiments, the solid-state lithium-ion conductor has a lithium-ion conductivity greater than 10 −7  S/cm. In some embodiments, the second portion  108  includes a lithium phosphorus oxynitride material. The lithium phosphorus oxynitride material may have a stoichiometry of Li x PO y N z  where 3.0≤x≤3.8, 3.0≤y≤4.0, and 0.1≤z≤1.0. The lithium phosphorus oxynitride material may be amorphous. 
     In some embodiments, a permeable membrane  122  is disposed along an exterior surface  124  of the second portion  108  and opposite the orifice  116 . The permeable membrane  122  may extend along the exterior surface  124  to portions of the second portion  108  not immediately opposite the orifice  116 . The permeable membrane may be any type of permeable membrane configured to transport lithium-ions therethrough, including separators for lithium-ion batteries. In some embodiments, the permeable membrane  122  exhibits a mean pore diameter less than 0.8 μm. Non-limiting examples of the permeable membrane  122  include polymer membranes of polyethylene (PE) and polypropylene (PP). Such polymer membranes may also include multilayer composites or blends of polyethylene (PE) and polypropylene (PP). However, other types of permeable membranes and materials can be used. 
     The anode  112  is preferably pure elemental lithium, but may contain incidental impurities less than 2 mole percent. The anode  112  may originate as a seed layer on the second portion  108  when fabricated. When fabricated as the seed layer, the anode  112  has a thickness greater than the seal  120 , if present, and is fabricated to contact the first portion  106 .  FIGS. 1A &amp; 1B  depict the anode  112  in corresponding states of operation different than the as-fabricated state (i.e., not as the seed layer). 
     During the charging and discharging processes, the anode  112  expands and contracts in volume.  FIG. 1A  illustrates the lithium-metal battery  100  during the charging process when the anode  112  is plated with lithium metal to expand in volume. Such plating occurs at the interface with the second portion  108 . An expansion of the anode  112  is shown in  FIG. 1A  by arrows  126 .  FIG. 1B  illustrates the lithium-metal battery  100  during the discharging process when the anode  112  is stripped to contract in volume. Such stripping occurs at the interface with the second portion  108 . A contraction of the anode  112  is shown in  FIG. 1B  by arrows  128 . 
     The enclosed cavity  110  is configured such that volumetric expansion and contraction of the anode  112  is accommodated entirely within. This configuration may utilize a cavity geometry that guides expansion and contraction along the longitudinal axis  114 . The enclosed cavity  110  may also be larger than that occupied by the anode  112  at maximum expansion. It will be appreciated that, by accommodating all volumes of the anode  112  during charging and discharging, the enclosed cavity  110  can allow outer dimensions of the anode cell  102  to remain virtually constant. 
     In some embodiments, the enclosed cavity  110  exhibits a vacuum of magnitude less than 100 torr. In some embodiments, the enclosed cavity  110  exhibits a vacuum of magnitude less than 10 torr. In some embodiments, the enclosed cavity  110  exhibits a vacuum of magnitude less than 1 torr. In some embodiments, the enclosed cavity  110  exhibits a vacuum of magnitude less than 10 −1  torr. 
     In some embodiments, the enclosed cavity  110  includes a gas disposed therein. In such embodiments, the gas is inert to reaction with lithium metal. Non-limiting examples of the gas include helium, neon, argon, krypton, xenon, and combinations thereof. Other inert gases and their combinations are possible. The gas in the enclosed cavity  110  may exhibit a reduced pressure of magnitude less than one atmosphere (i.e., &lt;760 torr). 
     In various embodiments, the lithium-metal battery  100  includes a cathode cell  130 . The cathode cell  130  is electrochemically-coupled to the anode cell  102 , which may occur through the permeable membrane  122 . The cathode cell  130  may be any cathode cell that utilizes lithium ions as a basis for electrochemical operation. 
     In some embodiments, the cathode cell  130  includes a cathode active material  132  in contact with the permeable membrane  122  along an area  134  opposite the orifice  116 . The area  134  may be bounded by the perimeter  118  of the orifice  116 , i.e., a projection of the perimeter  118  through the permeable membrane  122 . Non-limiting examples of the cathode active material  132  include compositions of lithium transition-metal (M) oxide such as LiMO 2 , LiM 2 O 4 , and LiMPO 4 . M can represent Ni, Co, Mn, or any combination thereof. Other compositions, however, are possible for the cathode active material  132 . 
     The cathode cell  130  may also include an electrolyte  136  comprising at least one solvated lithium species. The at least one solvated lithium species may include a lithium salt. Non-limiting examples of the lithium salt include LiPF 6 , LiBF 4 , LiClO 4 , LiSO 3 CF 3 , LiN(SO 2 CF 3 ) 2 , LiBC 4 O 8 , Li[PF 3 (C 2 CF 5 ) 3 ], and LiC(SO 2 CF 3 ) 3 . Other lithium salts are possible, including combinations of lithium salts. The electrolyte  136  permeates the cathode active material  132  and the permeable membrane  122  (if present). During operation of the lithium-metal battery  100 , the electrolyte  136  provides a medium through which lithium ions are exchanged between the second portion  108  and the cathode active material  132 . 
     The cathode cell  130  may additionally include a cathode current collector  138  in contact with the cathode active material  132 . The cathode current collector  138  is formed of an electrically-conductive material that is chemically stable to the cathode active material  132  and the electrolyte  136 . Such chemical stability also includes chemical stability of the electrolyte  136  towards the cathode current collector  138 . Non-limiting examples of the electrically-conductive material include aluminum, aluminum alloys, and carbonaceous materials (e.g., graphite). Other conductive materials, however, are possible.  FIGS. 1A &amp; 1B  depict the cathode current collector  138  as being a foil or sheet. However, this depiction is for purposes of illustration only. The current collector  138  may exhibit other shapes, including being integrated into a housing of the lithium-metal battery  100 . 
     In some embodiments, the electrolyte  136  includes a liquid solvent. In such embodiments, the liquid solvent may be an organic carbonate (e.g., ethylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl-methyl carbonate, etc.), an ionic liquid (e.g., 1-butyl-3-methylimidazolium hexafluorophosphate, 1-ethylpyridinium tetrafluoroborate, etc.), or some combination thereof. Other liquid solvents and their combinations are possible. In some embodiments, the electrolyte  136  includes a gel polymer. In these embodiments, the gel polymer may include polymeric hosts such as polyethylene oxide (PEO), polyacrylonitrile (PAN), polymethylmethacrylate (PMMA), and polyvinylidene fluoride (PVdF). Other gel polymers are possible. 
     It will be appreciated that the second portion  108  allows an interface between the anode cell  102  and the cathode cell  130  that separates the anode  112  from the electrolyte  136 . Such separation is advantageous given that the anode  112  comprises lithium metal. Many useful formulations of electrolyte  136  are unstable towards lithium metal, and if incorporated within the lithium-metal battery  100  in direct contact with the anode  112 , would decompose during charging and discharging. Separation of the anode  112  from the electrolyte  136  may also prevent a formation of lithium-metal dendrites, which can traverse the electrolyte  136  to form a short-circuit pathway between the anode cell  102  and the cathode cell  130  (e.g., between the anode  112  and the cathode current collector  138 ). 
     In some embodiments, the second portion  108  of the anode cell  102  directly contacts the cathode active material  132  of the cathode cell  130  (i.e., the permeable membrane  122  depicted in  FIGS. 1A-1C  is not present). In these embodiments, the cathode active material  132  extends along the exterior surface  124  to portions of the second portion  108  not immediately opposite the orifice  116  (e.g., opposite the seal  120 ). For example, and without limitation, the cathode active material  132  may extend to cover the exterior surface  124  in its entirety. 
     In operation, the lithium-metal battery  100  undergoes battery cycling that involves the charging and discharging processes. During the charging process, a charging electrical current flows through the first portion  106  of the container  104  and into the anode  112 , which is in contact with the container  104 . The charging electrical current originates at the cathode current collector  138  and reaches the container  104  via an electrical circuit (not shown). The charging electrical current is provided by an electrical power source, which may be regulated by the electrical circuit (e.g., to produce controlled voltage). 
     The charging electrical current induces positively-charged lithium ions to migrate from the cathode active material  132 , through the permeable membrane  122  (if present), and to the second portion  108 . Such migration proceeds through the electrolyte  136 , which contains the at least one lithium species solvated therein. At the second portion  108 , the positively-charged lithium ions diffuse therethrough to reach the anode  112 , where they neutralize a negative charge being supplied by the charging electrical current. This diffusion causes layers of lithium metal to plate onto the anode  112  at the interface with the second portion  108 . The anode  112  then expands volumetrically within the enclosed cavity  110  (see arrows  126  in  FIG. 1A ). The enclosed cavity  110  is sufficient in shape and size to accommodate the anode  112  at maximum expansion. The enclosed cavity  110  may include an excess volume as a margin of safety. 
     During the discharging process, the anode  112  strips at the interface to produce positively-charged lithium ions. Such mass loss causes the anode  112  to contract volumetrically within the enclosed cavity  110  (see arrows  128  in  FIG. 1B ). The positively-charged lithium ions diffuse through the second portion  108  where they are solvated by the electrolyte  136 . Transport through the electrolyte  136  allows the positively-charged lithium ions to reach the cathode active material  132 , where they are stored therein (e.g., via an intercalation process). In response, a discharging electrical current flows out of the first portion  106  of the container  104 , through the electrical circuit, and to the cathode current collector  138 . The electrical circuit may allow the discharging electrical current to power an electronic device or electric-power consuming apparatus. Upon reaching the cathode current collector  138 , the discharging electrical current flows into the cathode active material  132 , where it neutralizes the positively-charged lithium ions being stored. 
     Because all volumes associated with the anode  112  are contained within the enclosed cavity  110 , outer dimensions of the anode cell  102  remain virtually constant. Thus, the lithium-metal battery  100  exhibits an improved dimensional stability during operation. Moreover, the second portion  108  of the container  104  and the seal  120  allow the anode  112  to remain separated from an environment of the anode cell  102 , which includes separation from the electrolyte  136 . Such separation is advantageous when using formulations of electrolyte  136  that are reactive towards lithium metal. The second portion  108  serves as an ionic conductor that mediates chemically between the anode  112  and the electrolyte  136 . In some embodiments, the second portion  108  is assisted by the permeable membrane  122 , which resides on the exterior surface  124  of the second portion  108  and is exposed to the electrolyte  136 . 
     It will be appreciated that the lithium-metal battery  100  described in relation to  FIGS. 1A-1C  can be incorporated into a battery pack. The battery pack includes at least one lithium-metal battery  100  having an anode cell  102  electrochemically-coupled to a cathode cell  130 . The at least one lithium-metal battery  100  may be electrically coupled in series, in parallel, or any combination thereof. In various embodiments of the battery pack, the at least one lithium-metal battery  100  includes a stacked sequence of lithium-metal batteries  100 . In some of these embodiments, the at least one lithium-metal battery  100  lacks the permeable membrane  122 , i.e., the second portion  108  of the anode cell  102  directly contacts the cathode active material  132  of the cathode cell  130 . 
       FIG. 2A  presents a schematic diagram of a plurality of lithium-metal batteries  240  arranged in a stacked sequence, according to an illustrative embodiment. Features analogous to  FIGS. 1A-1C  and  FIG. 2A  are related via coordinated numerals that differ in increment by one hundred. Dashed lines shown a shape of the enclosed cavity  210 . The stacked sequence alternates between a first junction  242  formed by adjacent pairs of anode cells  202  and a second junction  244  formed by adjacent pairs of cathode cells  230 . 
     In some embodiments, the first junction  242  includes a common anode current collector  246  shared between adjacent pairs of anode cells  202 , as shown in  FIG. 2A . Such sharing may involve a “U-shaped” cross-section. In some embodiments, the first junction  242  includes a container wall shared in common between the corresponding first portions of adjacent pairs of anode cells  202  (e.g., an “H-shaped” cross-section in  FIGS. 1A-1C ). In these embodiments, such sharing may allow the corresponding first portions to function in combination as a single, extended anode current collector. In some embodiments, the second junction  244  includes a common cathode current collector  239  shared between adjacent pairs of cathode cells  230 , as shown in  FIG. 2A . 
     It will be appreciated that the common anode current collectors  246  and the common cathode current collectors  239  can be electrically coupled in parallel, in series, or any combination thereof.  FIG. 2B  presents the stacked sequence of  FIG. 2A , but electrically coupled in parallel, according to an illustrative embodiment. In  FIG. 2B , the common anode current collectors  246  are electrically-coupled to an anode bus  248  and the common cathode current collectors  239  are electrically-coupled to a cathode bus  250 . The anode bus  248  and the cathode bus  250  may correspond to terminals of the battery pack. A voltage potential between the anode bus  248  and the cathode bus  250  may be constant. However, electrical current flowing between the buses  248 ,  250  scales with a number of lithium-metal batteries  200  so-coupled. 
       FIG. 2C  presents the stacked sequence of  FIG. 2A , but electrically coupled in series, according to an illustrative embodiment. In  FIG. 2C , insulating elements  252  are disposed between cathode current collectors  254  and anode current collectors  256  associated with individual lithium-metal batteries  200 . The insulating elements  252  prevent electrical current from flowing between adjacent lithium-metal batteries  200  (i.e., flowing through the first and second junctions  242 ,  244 ). Conducting elements  258  electrically-couple the cathode current collectors  254  to the anode current collectors  256  along the stacked sequence. Such coupling allows a potential voltage of the stacked sequence to scale with a number of lithium-metal batteries therein. Electrical current along the stacked sequence may be constant. 
     A series electrical coupling may also be achieved by altering an arrangement of lithium-metal batteries  200  within the stacked sequence.  FIG. 2D  presents the stacked sequence of  FIG. 2A , but in which individual lithium-metal batteries  200  of the stacked sequence have aligned polarities. In this alignment, anode cells  202  and cathode cells  230  meet in pairs to form a third junction  260 . In some instances, such as that shown in  FIG. 2D , the third junction  260  contains a shared current collector  262 . The shared current collector  262  is stable to electrochemical processes within the anode cell  202  and the cathode cell  230  (e.g., formed of TiAlN or TiAlN-coated stainless steel). In some variations, the shared current collector  262  includes an anode current collector (e.g., copper foil) on one side and a cathode current collector (e.g., aluminum foil) on an opposite side. The anode current collector and the cathode current collector do not react with each other during operation and are inert when the lithium-metal batteries  200  are inactive. 
     Referring now back to  FIGS. 1A-1C , the battery pack may also involve arrays. In various embodiments, the at least one lithium-metal battery  100  includes an array of lithium-metal batteries  100 . The first portion  106  of the container  104  for each lithium-metal battery  100  may define a section of an extended first portion shared in common. Non-limiting examples of the extended first portion are described below in relation to  FIG. 3  and  FIG. 4 . 
       FIG. 3  presents a perspective view of part of an extended first portion  300  having cavities  302  with corresponding orifices  304  on a common side, according to an illustrative embodiment. Although the cavities  302  are depicted as having a hexagonal cross-section and longitudinal axes  306  aligned in parallel, this depiction is not intended as limiting. Other cross-sections and alignments are possible. For example, and without limitation, cross-sections for the cavities  302  can include square cross-sections, circular cross-sections, and rectangular cross-sections. The cavities  302  may also be canted relative to each other to form patterns (e.g., peaks, valleys, clusters, etc.). Moreover, the cavities  302  need not be ordered along a hexagonal array, as shown in  FIG. 3 . Other arrays are possible (e.g., rectangular). 
       FIG. 4  presents a perspective view of part of an extended first portion  400  having a first planar array of cavities  402  opposite a second planar array of cavities  404 , according to an illustrative embodiment. The corresponding orifices  406  open on opposite sides of the extended first portion  400 . The corresponding cavities  408  are ordered along a square (or rectangular) array. However, it will be understood that the cavities  408  of the arrays  402 ,  404  may be ordered in any type of planar ordering (e.g., hexagonal). 
     In  FIG. 4 , the first planar array of cavities  402  is depicted as being offset laterally relative to the second planar array of cavities  404 . However, this depiction is for purposes of illustration only. The cavities  408  of each planar array  402 ,  404  may be aligned such that cavities  408  on opposite sides share a common longitudinal axis between adjacent pairs. The cavities  408  of  FIG. 4  are also depicted with a common square cross-section and longitudinal axes  410  aligned in parallel. However, other cross-sections (e.g., circular, hexagonal, etc.) and alignments (e.g., canted) are possible. These cross-sections and alignments may also differ between arrays  402 ,  404  and between individual cavities  408  within an array. 
     Now referring back to  FIGS. 1A-1C , in embodiments involving the extended first portion, the array of lithium-metal batteries  100  may be oriented such that the corresponding enclosed cavities  110  have orifices  116  on a common side of the extended first portion (e.g., analogous to  FIG. 3 ). In these instances, the corresponding cathode cells  130  may be configured into a single, effective cathode cell that spans the extended first portion. Such configuration may include the cathode active material  132  and the cathode current collector  138  as single respective layers that extend to limits of the extended first portion. The second portion  108  and the permeable membrane  122  may also be single respective layers that extend to limits of the extended first portion. Thus, the array of lithium-metal batteries  100  may include a single cathode cell that is shared in common among a plurality of anode cells  102 . 
     The array of lithium-metal batteries  100  may also include a first planar array of lithium-metal batteries  100  opposite a second planar array of lithium-metal batteries  100 . The corresponding enclosed cavities  110  are oriented such that their orifices  116  open on opposite sides of the extended first portion (e.g., analogous to  FIG. 4 ). In such instances, the cathode cells  130  associated with each side may be configured into a single, effective cathode cell. Thus, the array of lithium-metal batteries  100  may include a single cathode cell on each side of the extended first portion. The single cathode cell may extend to limits of the extended first portion and may be shared in common among anode cells  102  on one side. The second portion  108  and the permeable membrane  122  may also be configured as single respective layers that extend to limits of the extended first portion on one or both sides. 
     The anode cells, the lithium-metal batteries, and the battery packs described herein can be used in any device that requires rechargeable or non-rechargeable batteries. In some variations, the anode cells, lithium-metal batteries, and the battery packs described herein can be packaged in to an apparatus that is battery-powered. 
     According to an illustrative embodiment, a method of manufacturing a lithium-metal battery includes the step of depositing a seed layer of lithium metal onto a surface of a substrate (e.g., by vacuum deposition, electroplating, etc.). The seed layer covers a predetermined area of the surface, which matches an orifice of a cavity within an electrically-conductive container. The substrate includes a solid-state lithium-ion conductor. The method also includes the step of coupling the electrically-conductive container to the substrate so as to enclose the seed layer within the cavity. Such enclosure includes the seed layer being seated within a perimeter of the orifice. The seed layer is in contact with the electrically-conductive container. In some embodiments, the step of coupling the electrically-conductive container to the substrate includes sealing the electrically-conductive container to the substrate. 
     It will be appreciated that the perimeter of the orifice matches that of the predetermined area. Thus, the seed layer, when enclosed within the cavity, has a boundary that aligns with the perimeter of the orifice. This alignment allows the seed layer to be in contact with the electrically-conductive container. In some embodiments, the electrically-conductive container is coupled to the substrate via a seal. The seal may be a hermetic seal. In these embodiments, the seed layer has a minimum thickness that is greater than a distance separating the electrically-conductive container from the substrate (e.g., a seal thickness). The minimum thickness may prevent a gap between the seed layer and the electrically-conductive container. 
     Non-limiting examples of the solid-state lithium-ion conductor include a lithium phosphorus oxynitride material (e.g., LiPON), a lithium boron oxynitirde material (e.g. LiBON), a lithium boron oxide material (e.g., LiBO 3 ), a lithium niobium oxide material (e.g., LiNbO 3 ), a lithium lanthanum zirconium oxide material (e.g., Li 7 La 3 Zr 2 O 12 ), a lithium phosphorus sulfide material (e.g., Li 3 PS 4 ), a lithium tin sulfide material (e.g., Li 4 SnS 4 ), and a lithium germanium phosphorus sulfide material (e.g., Li 10 GeP 2 S 12 ). Other solid-state lithium-ion conductors are possible. In some embodiments, the solid-state ionic conductor has a lithium-ion conductivity greater than 10 −7  S/cm. In some embodiments, the solid-state ionic conductor includes a lithium phosphorus oxynitride material. The lithium phosphorus oxynitride material may have a stoichiometry of Li x PO y N z  where 3.0≤x≤3.8, 3.0≤y≤4.0, and 0.1≤z≤1.0. The lithium phosphorus oxynitride material may be amorphous. 
     In some embodiments, the method further includes the step of depositing the solid-state lithium-ion conductor on a removable support (e.g., by vacuum deposition, electroplating, etc.). The removable support can be removed from the solid-state lithium-ion conductor before or after the substrate is coupled to electrically-conductive container. In some instances, the removable support is detached physically from the solid-state lithium-ion conductor. In other instances, the removable support is removed from the solid-state lithium-ion conductor through one or more sacrificial processes (e.g., dissolving in a solvent, melting, heating to decompose, etc.). 
     In some embodiments, the step of depositing the seed layer of lithium metal includes the step of depositing the solid-state lithium-ion conductor onto a cathode active material (e.g., by vacuum deposition, heat-molding, etc.). In these embodiments, the cathode active material may be configured as part of a cathode cell. 
     In some embodiments, the step of depositing the seed layer of lithium metal includes the step of depositing the solid-state lithium-ion conductor onto a permeable membrane having a first surface and a second surface. In these embodiments, the first surface forms an interface with the solid-state lithium-ion conductor. An exposed surface of the solid-state lithium-ion conductor defines the first side of the substrate. The substrate further includes the permeable membrane. 
     The permeable membrane may be any type of permeable membrane configured to transport lithium-ions therethrough, including separators for lithium-ion batteries. In some embodiments, the permeable membrane exhibits a mean pore diameter less than 0.8 μm. Non-limiting examples of the permeable membrane include polymer membranes of polyethylene (PE) and polypropylene (PP). Such polymer membranes may also include multilayer composites or blends of polyethylene (PE) and polypropylene (PP). However, other types of permeable membranes and materials can be used. 
     In some embodiments, the step of depositing the solid-state lithium-ion conductor onto the permeable membrane includes the step of contacting a cathode active material with a cathode current collector to produce a preform. In such embodiments, the step of depositing the solid-state lithium-ion conductor onto the permeable membrane also includes the step of contacting the cathode active material of the preform with the second surface of the permeable membrane and the step of applying heat, pressure, or a combination thereof, to the preform in contact with the permeable membrane. The substrate further includes the cathode active material and the cathode current collector. 
     Non-limiting examples of the cathode active material include compositions of lithium transition-metal (M) oxide such as LiMO 2 , LiM 2 O 4 , and LiMPO 4 . M can represent Ni, Co, Mn, or any combination thereof. Other compositions, however, are possible for the cathode active material. The cathode current collector may be formed of an electrically-conductive material such as aluminum, aluminum alloys, and carbonaceous materials (e.g., graphite). Other electrically-conductive materials, however, are possible. The cathode current collector may be a foil or sheet. 
     In some embodiments, the step of coupling the electrically-conductive container to the substrate includes the step of coupling an anode terminal to the electrically-conductive container and the step of coupling the cathode terminal to the cathode current collector. In further embodiments, the step of coupling the electrically-conductive container to the substrate includes the step of disposing, into a pouch, the electrically-conductive container coupled to the substrate; the step of filling the pouch with an electrolyte; and the step of sealing the pouch. 
     The anode terminal may be formed of any electrically-conductive material chemically compatible with the electrically-conductive material. Similarly, the cathode terminal may be formed of any electrically-conductive material chemically compatible with the cathode current collector. 
     The electrolyte includes at least one solvated lithium species. The at least one solvated lithium species may include a lithium salt. Non-limiting examples of the lithium salt include LiPF 6 , LiBF 4 , LiClO 4 , LiSO 3 CF 3 , LiN(SO 2 CF 3 ) 2 , LiBC 4 O 8 , Li[PF 3 (C 2 CF 5 ) 3 ], and LiC(SO 2 CF 3 ) 3 . Other lithium salts are possible, including combinations of lithium salts. The electrolyte may permeate the cathode active material and the permeable membrane (if present). The electrolyte may also include a liquid solvent. The liquid solvent may be an organic carbonate (e.g., ethylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl-methyl carbonate, etc.), an ionic liquid (e.g., 1-butyl-3-methylimidazolium hexafluorophosphate, 1-ethylpyridinium tetrafluoroborate, etc.), or some combination thereof. Other liquid solvents and their combinations are possible. In some embodiments, the electrolyte includes a gel polymer. In these embodiments, the gel polymer may include polymeric hosts such as polyethylene oxide (PEO), polyacrylonitrile (PAN), polymethylmethacrylate (PMMA), and polyvinylidene fluoride (PVdF). Other gel polymers are possible. 
     The foregoing description, for purposes of explanation, used specific nomenclature to provide a thorough understanding of the described embodiments. However, it will be apparent to one skilled in the art that the specific details are not required in order to practice the described embodiments. Thus, the foregoing descriptions of the specific embodiments described herein are presented for purposes of illustration and description. They are not targeted to be exhaustive or to limit the embodiments to the precise forms disclosed. It will be apparent to one of ordinary skill in the art that many modifications and variations are possible in view of the above teachings.

Metadata:
Filing Date: 20161220
Publication Date: 20201215
Grant Date: 20201215
Priority Date: 20160226
Inventors: NEUDECKER, BERND J.
SNYDER, SHAWN W.
MANK, RICHARD M.
Assignee: APPLE INC
CPC Classifications: [{"code": "H01M4/134", "inventive": true, "first": true, "tree": "[]"}, {"code": "Y02P70/50", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01M4/1395", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01M10/058", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01M10/052", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01M10/0445", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01M4/1395", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01M4/661", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01M4/382", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01M4/661", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01M10/0445", "inventive": false, "first": false, "tree": "[]"}, {"code": "Y02E60/10", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01M10/052", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01M4/382", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01M10/058", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01M4/134", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01M4/134", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01M10/058", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01M4/1395", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01M10/052", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01M4/661", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01M2/18", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01M4/382", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01M10/0445", "inventive": false, "first": false, "tree": "[]"}]
Family ID: 59680185