Surface treatment for lithium metal anodes

Abstract

This invention relates to surface treatment for lithium metal anodes. A method for preparing a lithium metal electrode for an electrochemical battery cell (such as a lithium metal battery) includes introducing a treatment gas into a chamber comprising an electrode precursor. The treatment gas may include reactant gases and / or plasma. The electrode precursor comprises lithium metal and a passivation layer. The method further includes forming the lithium metal electrode by contacting the treatment gas with the passivation layer to remove at least a portion of the passivation layer. This disclosure also provides pretreated electrodes and electrode assemblies.

Description

Technical Field

[0001] introduction

[0002] The information provided in this section is for the purpose of presenting the general context of this disclosure. The work of the currently named inventors, to the extent described in this section, and in respect of aspects of that description that may not otherwise qualify as prior art at the time of filing, is neither expressly nor implicitly considered prior art to this disclosure.

[0003] This disclosure relates to a surface treatment for lithium anodes (such as those used in electrochemical battery cells, e.g., lithium metal batteries). Background Technology

[0004] High-energy-density electrochemical battery cells (such as lithium-ion batteries) can be used in a variety of consumer products and vehicles, such as hybrid electric vehicles (HEVs) and electric vehicles (EVs). Typical lithium-ion and lithium-sulfur batteries include a first electrode, a second electrode, an electrolyte material, and a separator. One electrode serves as the positive electrode or cathode, and the other as the negative electrode or anode. A stack of battery cells can be electrically connected to increase the total output. Conventional rechargeable lithium-ion batteries operate by reversibly transferring lithium ions back and forth between the negative and positive electrodes. A separator and electrolyte can be disposed between the negative and positive electrodes. The electrolyte is suitable for conducting lithium ions and can be in solid (e.g., solid-state diffusion), gel, or liquid form. Lithium ions move from the cathode (positive electrode) to the anode (negative electrode) during battery charging and in the opposite direction during battery discharge.

[0005] Many different materials can be used to create components for lithium-ion batteries. Common negative electrode materials include lithium-intercalated materials or alloy host materials, such as carbon-based materials, such as lithium-graphite intercalation compounds, or lithium-silicon compounds, lithium-tin alloys, and lithium titanate (Li). 4+x Ti5O 12 (where 0 ≤ x ≤ 3), such as Li4Ti5O 12 (LTO). When the negative electrode is made of metallic lithium, the electrochemical cell is considered a lithium metal battery or cell. Lithium metal, used as the negative electrode in rechargeable batteries, offers various potential advantages, including the highest theoretical capacity and the lowest electrochemical potential. Therefore, batteries incorporating lithium metal anodes can achieve higher energy densities, potentially doubling storage capacity and halving battery size while still maintaining the same duration as other lithium-ion batteries. Thus, lithium metal batteries are among the most promising candidates for high-energy storage systems. However, lithium metal batteries also have potential drawbacks, including the possibility of unreliable or degraded performance and potential premature electrochemical cell failure. Summary of the Invention

[0006] In various aspects, this disclosure provides a method for preparing a lithium metal electrode for an electrochemical battery cell. The method includes introducing a process gas into a chamber comprising an electrode precursor. The electrode precursor comprises lithium metal and a passivation layer. The method further includes forming the lithium metal electrode by contacting the process gas with the passivation layer to remove at least a portion of the passivation layer.

[0007] In one aspect, the process gas is a single process gas.

[0008] In one aspect, the processing gas is the reactant. The reactant is configured to react with at least a portion of the passivation layer.

[0009] In one aspect, the reactants are configured to react with at least a portion of the passivation layer to alter the composition of the passivation layer.

[0010] In one aspect, the reactants are selected from the group consisting of: trimethylaluminum (TMA); trimethyl phosphate (TMPO), nitrogen (N2), water (H2O), oxygen (O2), ozone (O3), triethyl phosphate (TEPO), titanium isopropoxide (TTIP), or any combination thereof.

[0011] In one aspect, the reactants are configured to react with at least a portion of the passivation layer to replace functional groups on the surface of the lithium metal electrode.

[0012] In one aspect, the processing gas is a plasma configured to mechanically bond the passivation layer to remove at least a portion of the passivation layer.

[0013] In one aspect, plasma is generated by introducing compounds selected from the group consisting of Ar, O2, O3, N2, NH3, or any combination thereof.

[0014] In one aspect, the indoor temperature is greater than or equal to about 20°C and less than or equal to about 90°C.

[0015] In one respect, the room is essentially airless.

[0016] In one aspect, the processing chamber includes a first processing gas comprising reactants; and a second processing gas comprising plasma.

[0017] In one aspect, the lithium metal electrode is configured to be in direct contact with the gel polymer electrolyte.

[0018] In one aspect, the lithium metal electrode is configured to be in direct contact with a liquid electrolyte having a viscosity greater than or equal to about 0.5 cP.

[0019] In one aspect, the surface of the lithium metal electrode is configured to have a contact angle with the electrolyte of greater than or equal to about 0° to less than or equal to about 90°.

[0020] In one aspect, the electrochemical assembly including a lithium metal electrode is configured to have a capacity greater than or equal to about 1 mAh / cm². 2 to less than or equal to about 5 mAh / cm 2 Surface discharge capacity.

[0021] In various aspects, this disclosure provides a method for preparing a lithium metal electrode assembly for an electrochemical battery cell. The method includes introducing a process gas into a chamber comprising an electrode precursor. The electrode precursor comprises lithium metal and a passivation layer. The method further includes contacting a bonding gas with the passivation layer to remove at least a portion of the passivation layer. The method further includes configuring an electrolyte to be in direct contact with the surface of the lithium metal electrode.

[0022] In one respect, the electrolyte is a gel polymer electrolyte.

[0023] In one aspect, the arrangement includes disposing a layer on a surface. The layer includes a monomer and an initiator. The arrangement also includes crosslinking the monomer by exposing the layer to UV radiation to form a gel polymer electrolyte.

[0024] In one aspect, the electrolyte is a liquid electrolyte having a viscosity greater than or equal to about 0.5 cP.

[0025] In various aspects, this disclosure provides a lithium metal battery. The lithium metal battery includes a positive electrode, a pretreated lithium metal electrode, an electrolyte, and a separator. The positive electrode includes a positively active material. The electrolyte is in direct contact with the pretreated lithium metal electrode. The electrolyte includes one of the following: (i) a gel polymer electrolyte, or (ii) a liquid electrolyte having a viscosity greater than or equal to about 0.5 cP. The separator is ion-conducting and electrically insulating. The pretreated lithium metal electrode is configured to have a contact angle with the electrolyte greater than or equal to about 0° to less than or equal to about 90°. The lithium metal battery is configured to have a capacitance greater than or equal to about 1 mAh / cm³. 2 to less than or equal to about 5 mAh / cm 2 Surface discharge capacity.

[0026] This invention includes the following technical solutions:

[0027] Option 1. A method for preparing a lithium metal electrode for an electrochemical battery cell, the method comprising:

[0028] Processing gas is introduced into a chamber including an electrode precursor comprising lithium metal and a passivation layer; and

[0029] The lithium metal electrode is formed by contacting the processing gas with the passivation layer to remove at least a portion of the passivation layer.

[0030] Option 2. The method according to Option 1, wherein the processing gas is a single processing gas.

[0031] Option 3. The method according to Option 1, wherein the processing gas is a reactant configured to react with at least a portion of the passivation layer.

[0032] Option 4. The method according to Option 3, wherein the reactant is configured to react with at least a portion of the passivation layer to change the composition of the passivation layer.

[0033] Option 5. The method according to Option 3, wherein the reactants are selected from the group consisting of: trimethylaluminum (TMA); trimethyl phosphate (TMPO), nitrogen (N2), water (H2O), oxygen (O2), ozone (O3), triethyl phosphate (TEPO), titanium isopropoxide (TTIP), or any combination thereof.

[0034] Option 6. The method according to Option 3, wherein the reactant is configured to react with at least a portion of the passivation layer to replace functional groups on the surface of the lithium metal electrode.

[0035] Option 7. The method according to Option 1, wherein the processing gas is plasma, and the plasma is configured to mechanically bond the passivation layer to remove at least a portion of the passivation layer.

[0036] Option 8. The method according to Option 7, wherein the introduction comprises generating the plasma from a compound selected from the group consisting of: Ar, O2, O3, N2, NH3, or any combination thereof.

[0037] Option 9. The method according to Option 1, wherein the temperature of the indoor unit is greater than or equal to about 20°C and less than or equal to about 90°C.

[0038] Option 10. The method according to Option 1, wherein the chamber is substantially airless.

[0039] Option 11. The method according to Option 1, wherein the processing chamber includes a first processing gas comprising reactants; and a second processing gas comprising plasma.

[0040] Option 12. The method according to Option 1, wherein the lithium metal electrode is configured to be in direct contact with the gel polymer electrolyte.

[0041] Option 13. The method according to Option 1, wherein the lithium metal electrode is configured to be in direct contact with a liquid electrolyte having a viscosity greater than or equal to about 0.5 cP.

[0042] Option 14. The method according to Option 1, wherein the surface of the lithium metal electrode is configured to have a contact angle with the electrolyte of greater than or equal to about 0° to less than or equal to about 90°.

[0043] Option 15. The method according to Option 1, wherein the electrochemical assembly including the lithium metal electrode is configured to have a capacity greater than or equal to about 1 mAh / cm². 2 to less than or equal to about 5 mAh / cm 2 Surface discharge capacity.

[0044] Option 16. A method for preparing a lithium metal electrode assembly for an electrochemical battery cell, the method comprising:

[0045] Processing gas is introduced into a chamber containing an electrode precursor, which includes lithium metal and a passivation layer;

[0046] The bonding gas is brought into contact with the passivation layer to remove at least a portion of the passivation layer; and

[0047] The electrolyte is configured to be in direct contact with the surface of the lithium metal electrode.

[0048] Option 17. The method according to Option 16, wherein the electrolyte is a gel polymer electrolyte.

[0049] Option 18. The method according to Option 16, wherein the setting includes:

[0050] A layer is disposed on the surface, the layer comprising a monomer and an initiator.

[0051] The monomers are crosslinked by exposing the layer to UV radiation to form the gel polymer electrolyte.

[0052] Option 19. The method according to Option 16, wherein the electrolyte is a liquid electrolyte having a viscosity greater than or equal to about 0.5 cP.

[0053] Option 20. A lithium metal battery, comprising:

[0054] Positive electrode, which includes positively charged active material;

[0055] Pretreated lithium metal electrodes; and

[0056] An electrolyte that is in direct contact with the pretreated lithium metal electrode, said electrolyte comprising one of the following:

[0057] (i) Gel polymer electrolyte, or

[0058] (ii) A liquid electrolyte having a viscosity greater than or equal to about 0.5 cP; and

[0059] A separator between the positive electrode and the pretreated lithium metal electrode, the separator being ion-conducting and electrically insulating, wherein:

[0060] The pretreated lithium metal electrode is configured to have a contact angle with the electrolyte of greater than or equal to about 0° to less than or equal to about 90°, and

[0061] The lithium metal battery is configured to have a capacity greater than or equal to about 1 mAh / cm³. 2 to less than or equal to about 5 mAh / cm 2 Surface discharge capacity.

[0062] Further applicable areas of this disclosure will become apparent from the detailed description, claims, and drawings. The detailed description and specific examples are intended for illustrative purposes only and are not intended to limit the scope of this disclosure. Attached Figure Description

[0063] This disclosure will be more fully understood from the detailed description and accompanying drawings, in which:

[0064] Figure 1 This is a schematic diagram of an electrochemical battery cell used to cycle lithium ions.

[0065] Figure 2 This is a schematic illustration of a method for pretreating a lithium metal electrode according to various aspects of this disclosure;

[0066] Figure 3 This is a cross-sectional view of an electrode according to various aspects of this disclosure, the electrode being based on Figure 2 The method is formed;

[0067] Figure 4 This is a cross-sectional view of another electrode according to various aspects of this disclosure, the electrode being based on Figure 2 The method is formed;

[0068] Figure 5 This is a cross-sectional view of an electrode assembly according to various aspects of this disclosure, the electrode assembly including Figure 3 The electrodes;

[0069] Figure 6These are photographs depicting the comparative wettability of a first untreated lithium metal sample and a second reactant-treated lithium metal sample prepared according to various aspects of this disclosure;

[0070] Figure 7 These are photographs depicting the comparative wettability of a first untreated lithium metal sample and a second plasma-treated lithium metal sample prepared according to various aspects of this disclosure; and

[0071] Figure 8 It is a graph depicting the comparative cycle performance of a first lithium metal battery (including an untreated lithium metal electrode), a second lithium metal battery (including a reactant-treated lithium metal electrode) according to various aspects of the present disclosure, and a third lithium metal battery (including a plasma-treated lithium metal electrode) according to various aspects of the present disclosure.

[0072] In the accompanying drawings, reference numerals may be reused to identify similar and / or identical elements. Detailed Implementation

[0073] Example embodiments are provided so that this disclosure will be thorough and will fully convey the scope to those skilled in the art. Numerous specific details, such as examples of specific ingredients, components, apparatuses, and methods, are set forth to provide a thorough understanding of embodiments of this disclosure. It will be apparent to those skilled in the art that the example embodiments can be implemented in many different forms without employing the specific details, and neither the specific details nor the example embodiments should be construed as limiting the scope of this disclosure. In some example embodiments, well-known processes, well-known apparatus structures, and well-known techniques are not described in detail.

[0074] The terminology used herein is for the purpose of describing particular exemplary embodiments only and is not intended to be limiting. As used herein, the singular forms “a,” “an,” and “the” may also be intended to include the plural forms unless the context clearly indicates otherwise. The terms “comprises,” “comprising,” “including,” and “having” are inclusive and therefore specify the presence of stated features, elements, components, steps, integers, operations, and / or parts, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, parts, and / or groups thereof. While the open-ended term “comprising” is to be understood as a non-limiting term used to describe and claim the various embodiments set forth herein, in some aspects, this term may alternatively be understood as a more restrictive and binding term, such as “consisting of” or “substantially consisting of.” Therefore, for any given embodiment recounting components, materials, parts, elements, features, integers, operations, and / or process steps, this disclosure also specifically includes embodiments consisting of or substantially consisting of such stated components, materials, parts, elements, features, integers, operations, and / or process steps. In the case of “consisting of…”, alternative embodiments exclude any additional ingredients, materials, components, elements, features, integers, operations, and / or process steps. In the case of “essentially composed of…”, any additional ingredients, materials, components, elements, features, integers, operations, and / or process steps that substantially affect the essential and novel characteristics are excluded from such embodiments. However, embodiments may include any ingredients, materials, components, elements, features, integers, operations, and / or process steps that do not substantially affect the essential and novel characteristics.

[0075] Any method steps, processes, and operations described herein shall not be construed as necessarily requiring them to be performed in the particular order discussed or illustrated, unless specifically identified as such. It will also be understood that additional or alternative steps may be employed unless otherwise indicated.

[0076] When a component, element, or layer is referred to as “on another component or layer,” “joined to,” “connected to,” or “linked to” another component or layer, it may be directly joined, connected to, or linked to the other component, element, or layer, or an intermediary element or layer may be present. In contrast, when an element is referred to as “directly on another component or layer,” “directly joined to,” “directly connected to,” or “directly linked to” another component or layer, an intermediary element or layer may not be present. Other terms used to describe relationships between elements should be interpreted in a similar manner (e.g., “between” versus “directly between,” “adjacent” versus “directly adjacent,” etc.). As used herein, the term “and / or” includes any and all combinations of one or more of the associated listed items.

[0077] Although the terms first, second, third, etc., may be used herein to describe various steps, elements, components, regions, layers, and / or sections, these steps, elements, components, regions, layers, and / or sections should not be limited by these terms unless otherwise indicated. These terms may be used only to distinguish one step, element, component, region, layer, or section from another. Terms such as “first,” “second,” and other numerical terms used herein do not imply sequence or order unless explicitly indicated by the context. Therefore, the first step, element, component, region, layer, or section discussed below may be referred to as the second step, element, component, region, layer, or section without departing from the teachings of the exemplary embodiments.

[0078] For ease of description, spatial or temporal terms such as “before,” “after,” “inside,” “outside,” “below,” “below,” “down,” “above,” “up,” etc., may be used herein to describe the relationship between one element or feature as illustrated in the accompanying drawings and another element or feature. In addition to the orientations depicted in the accompanying drawings, spatial or temporal terms may also be intended to cover different orientations of the apparatus or system during use or operation.

[0079] Throughout this disclosure, numerical values ​​represent approximate measurements or ranges to cover small deviations from a given value and embodiments having approximately the mentioned value as well as those having the exact mentioned value. Except for the working examples provided at the end of the detailed description, all numerical values ​​of parameters (e.g., quantities or conditions) in this specification (including the appended claims) will be understood to be modified in all cases by the term “about,” regardless of whether “about” actually precedes the numerical value. “About” indicates that the stated numerical value allows for some slight inaccuracy (a degree of approximation to the value; approximately or reasonably close to the value; almost). If the inaccuracy provided by “about” is not otherwise understood in this common sense in the art, then “about” as used herein at least indicates a variation that can be produced by common methods of measuring and using such a parameter. For example, “about” may include a variation of less than or equal to 5%, optionally less than or equal to 4%, optionally less than or equal to 3%, optionally less than or equal to 2%, optionally less than or equal to 1%, optionally less than or equal to 0.5%, and in some respects optionally less than or equal to 0.1%.

[0080] Additionally, the disclosure of the range includes the disclosure of all values ​​across the entire range and the disclosure of further subdivided ranges, including the endpoints and subranges given for these ranges.

[0081] Exemplary embodiments will now be described more fully with reference to the accompanying drawings.

[0082] This technology relates to rechargeable lithium metal batteries, which can be used in vehicle applications. However, this technology can also be used in other electrochemical devices that cycle lithium ions, such as handheld electronic devices or energy storage systems (ESS).

[0083] Functions, structure, and components of a typical electrochemical battery cell

[0084] As background, Figure 1 Exemplary and schematic illustrations of an electrochemical cell unit (also referred to as a battery) 20 are shown. Although the illustrated examples include a single positive electrode or cathode and a single negative electrode or anode, those skilled in the art will recognize that this disclosure also contemplates various other configurations, including those having one or more cathodes and one or more anodes, and various current collectors having electroactive layers disposed on or adjacent to one or more of their surfaces.

[0085] A typical lithium-ion battery 20 includes a first electrode (such as a negative electrode 22 or anode), an opposing second electrode (such as a positive electrode 24 or a cathode), and a separator 26 disposed therebetween and / or an electrolyte 30. Although not shown, batteries or battery cells are often electrically connected in a stacked or wound configuration in lithium-ion battery packs to improve overall output. Lithium-ion batteries operate by reversibly transferring lithium ions between the first and second electrodes. For example, lithium ions can move from the positive electrode 24 to the negative electrode 22 during battery charging and in the opposite direction during battery discharge. The electrolyte 30 is adapted to conduct lithium ions and can be in the form of a liquid or gel.

[0086] When a liquid or semi-liquid / gel electrolyte is used, a separator 26 (e.g., a microporous polymer separator) is thus disposed between the two electrodes 22, 24 and may include an electrolyte 30, which may also be present in the pores of the negative electrode 22 and the positive electrode 24. A negative electrode current collector 32 may be positioned at or near the negative electrode 22, and a positive electrode current collector 34 may be positioned at or near the positive electrode 24. An interruptible external circuit 40 and a load device 42 connect the negative electrode 22 (through its current collector 32) and the positive electrode 24 (through its current collector 34).

[0087] Battery 20 is capable of generating current during discharge through a reversible electrochemical reaction that occurs when external circuit 40 is closed (to connect negative electrode 22 and positive electrode 24) and negative electrode 22 has a lower potential than positive electrode 24. The chemical potential difference between positive electrode 24 and negative electrode 22 drives electrons generated at negative electrode 22 by a reaction (e.g., oxidation of intercalated lithium) through external circuit 40 toward positive electrode 24. Lithium ions also generated at negative electrode 22 simultaneously transfer toward positive electrode 24 through electrolyte 30 contained in separator 26. Electron flow through external circuit 40 and lithium ion migration across separator 26 containing electrolyte solution 30 to form intercalated lithium at positive electrode 24. As described above, electrolyte 30 is also typically present in negative electrode 22 and positive electrode 24. The current through external circuit 40 can be utilized and directed through load device 42 until the lithium in negative electrode 22 is depleted and the capacity of battery 20 decreases.

[0088] Battery 20 can be charged or recharged at any time by connecting an external power source to the lithium-ion battery 20 to reverse the electrochemical reactions that occur during battery discharge. Connecting an external electrical energy source to battery 20 promotes a reaction at the positive electrode 24 (e.g., non-spontaneous oxidation of transition metal ions), resulting in the generation of electrons and lithium ions. Lithium ions flow from the negative electrode 22 across the separator 26 through the electrolyte 30 to replenish lithium at the positive electrode 24 for use during the next battery discharge event. Thus, a complete discharge event followed by a complete charge event is considered a cycle in which lithium ions circulate between the positive electrode 24 and the negative electrode 22. The external power source that can be used to charge battery 20 may vary depending on the size, construction, and specific end use of battery 20. Some well-known and exemplary external power sources include, but are not limited to, AC-DC converters and vehicle alternators connected to the AC grid via a wall socket.

[0089] In many lithium-ion battery configurations, each of the negative electrode current collector 32, negative electrode 22, separator 26, positive electrode 24, and positive electrode current collector 34 is fabricated as a relatively thin layer (e.g., with a thickness from a few micrometers to a few tenths of a millimeter or less) and assembled in electrically parallel arrangement to provide suitable electrical energy and power. The negative electrode current collector 32 and the positive electrode current collector 34 collect free electrons from and move free electrons to the external circuit 40, respectively.

[0090] Furthermore, as described above, when using a liquid or semi-liquid electrolyte, the separator 26 operates as an electrical insulator by being sandwiched between the negative electrode 22 and the positive electrode 24 to prevent physical contact and thus prevent short circuits. The separator 26 not only provides a physical and electrical barrier between the two electrodes 22, 24, but also contains the electrolyte solution in an open-pore network during lithium-ion cycling to facilitate the operation of the battery 20.

[0091] Battery 20 may include a variety of other components, though not depicted herein, that are known to those skilled in the art. For example, battery 20 may include a housing, gaskets, end caps, tabs, battery terminals, and any other conventional components or materials that may be located within battery 20 (including between or around the negative electrode 22, the positive electrode 24, and / or the separator 26). Figure 1 The battery 20 shown includes a liquid electrolyte 30 and illustrates a representative concept for battery operation.

[0092] Electrodes can typically be incorporated into a variety of commercial battery designs, such as prismatic battery cells, wound cylindrical battery cells, button cell cells, pouch cell cells, or other suitable battery cell shapes. These battery cells can include a single electrode structure for each polarity or a stacked structure having multiple positive and negative electrodes assembled in parallel and / or series electrical connections. In particular, the battery can include a stack of alternating positive and negative electrodes and spacers disposed therebetween. While positively active materials can be used in the battery for primary or single-charge use, the resulting battery typically exhibits the desired cycling properties for secondary battery use over multiple cycles of the battery cell.

[0093] As described above, the size and shape of battery 20 can vary depending on the specific application it is designed for. Battery-powered vehicles and handheld consumer electronics are two examples, where battery 20 will most likely be designed with different sizes, capacities, and power output specifications. Battery 20 can also be connected in series or parallel with other similar lithium-ion cells or batteries to generate greater voltage output, energy, and power if required by the load device 42. Thus, battery 20 is capable of generating current for load device 42, which is part of external circuit 40. Load device 42 can be powered by the current flowing through external circuit 40 when battery 20 is discharging. While electrical load device 42 can be any number of known electrical power supply devices, some specific examples include electric motors for electrified vehicles, laptop computers, tablet computers, mobile phones, and cordless power tools or appliances. Load device 42 can also be a power generation device that charges battery 20 for the purpose of storing electrical energy.

[0094] This technology relates to the fabrication of improved electrochemical battery cells, particularly lithium-ion batteries. Such battery cells are used in various vehicle or automotive transportation applications (e.g., motorcycles, boats, tractors, buses, motorhomes, campervans, and tanks). However, this technology can be used in a wide range of other industries and applications, including, by way of example, aerospace components, consumer products, devices, buildings (e.g., houses, offices, sheds, and warehouses), office equipment and furniture, as well as industrial equipment machinery, agricultural or farm equipment, or heavy machinery.

[0095] electrolytes

[0096] Re-reference Figure 1The positive electrode 24, negative electrode 22, and separator 26 may each include an electrolyte solution or system 30 within their pores, which is capable of conducting lithium ions between the negative electrode 22 and the positive electrode 24. Any suitable electrolyte 30 capable of conducting lithium ions between the negative electrode 22 and the positive electrode 24 can be used in the lithium-ion battery 20, whether it is in solid, liquid, or gel form. In some aspects, the electrolyte 30 may be a non-aqueous liquid electrolyte solution comprising a lithium salt dissolved in an organic solvent or a mixture of organic solvents. Many non-aqueous liquid electrolyte 30 solutions can be used in the lithium-ion battery 20. In some variations, the electrolyte 30 may comprise an aqueous solvent (i.e., an aqueous-based solvent) or a mixed solvent (e.g., an organic solvent comprising at least 1% water by weight).

[0097] Suitable lithium salts typically possess inert anions. Examples of lithium salts that can dissolve in organic solvents to form non-aqueous liquid electrolyte solutions include lithium hexafluorophosphate (LiPF6); lithium perchlorate (LiClO4); lithium tetrachloroaluminate (LiAlCl4); lithium iodide (LiI); lithium bromide (LiBr); lithium thiocyanate (LiSCN); lithium tetrafluoroborate (LiBF4); lithium difluorooxalate borate (LiBF2(C2O4)) (LiODFB); lithium tetraphenylborate (LiB(C6H5)4); and bis(hydroxyethyl)pyridine ... Lithium (oxalate-bound)borate (LiB(C2O4)2) (LiBOB); lithium tetrafluorooxalate phosphate (LiPF4(C2O4)) (LiFOP); lithium nitrate (LiNO3); lithium hexafluoroarsenate (LiAsF6); lithium trifluoromethanesulfonate (LiCF3SO3); lithium bis(trifluoromethanesulfonyl)imide (LITFSI) (LiN(CF3SO2)2); lithium (fluorosulfonyl)imide (LiN(FSO2)2) (LiSFI); and combinations thereof. In some variations, electrolyte 30 may include a lithium salt with a concentration of 1 M.

[0098] By way of example, these lithium salts can be dissolved in a variety of organic solvents, such as organic ethers or organic carbonates. Organic ethers may include dimethyl ethers, glycol dimethyl ethers (ethylene glycol dimethyl ether or dimethoxyethane (DME, e.g., 1,2-dimethoxyethane)), diethylene glycol dimethyl ethers (diethylene glycol dimethyl ether or bis(2-methoxyethyl) ether), triethylene glycol dimethyl ethers (tris(ethylene glycol) dimethyl ether), other chain-structured ethers (such as 1,2-diethoxyethane, ethoxymethoxyethane, 1,3-dimethoxypropane (DMP)), cyclic ethers (such as tetrahydrofuran, 2-methyltetrahydrofuran), and combinations thereof. In certain variations, the organic ether compound is selected from the group consisting of tetrahydrofuran, 2-methyltetrahydrofuran, dioxolane, dimethoxyethane (DME), diethylene glycol dimethyl ether (diethylene glycol dimethyl ether), triethylene glycol dimethyl ether (tris(ethylene glycol) dimethyl ether), 1,3-dimethoxypropane (DMP), and combinations thereof. Carbonate-based solvents may include various alkyl carbonates, such as cyclic carbonates (e.g., ethylene carbonate (EC), propylene carbonate (PC), butyl carbonate) and acyclic carbonates (e.g., dimethyl carbonate (DMC), diethyl carbonate (DEC), methyl ethyl carbonate (EMC)). Ether-based solvents include cyclic ethers (e.g., tetrahydrofuran, 2-methyltetrahydrofuran, 1,3-dioxolane) and chain-structured ethers (e.g., 1,2-dimethoxyethane, 1,2-diethoxyethane, ethoxymethoxyethane).

[0099] In various embodiments, suitable solvents other than those described above may be selected from propylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, γ-butyrolactone, dimethyl sulfoxide, acetonitrile, nitromethane, and mixtures thereof.

[0100] porous separator

[0101] In some variations, the porous separator 26 may include a microporous polymer separator comprising a polyolefin, including those composed of homopolymers (derived from a single monomer component) or hybrids (derived from more than one monomer component), which may be either linear or branched. In some aspects, the polyolefin may be polyethylene (PE), polypropylene (PP), or a blend of PE and PP, or a multilayer structured porous membrane of PE and / or PP. Commercially available polyolefin porous separator 26 membranes include CELGARD® 2500 (single-layer polypropylene separator) and CELGARD® 2340 (triple-layer polypropylene / polyethylene / polypropylene separator) from Celgard LLC.

[0102] When the porous separator 26 is a microporous polymer separator, it can be a single-layer or multi-layer laminate. For example, in one embodiment, a single layer of polyolefin can form the entire microporous polymer separator 26. In other aspects, the separator 26 can be, for example, a fibrous membrane having a large number of pores extending between opposing surfaces and can have a thickness of less than 1 mm. However, as another example, multiple discrete layers of similar or different polyolefins can be assembled to form the microporous polymer separator 26. Alternatively, or in addition to polyolefins, the microporous polymer separator 26 may also include other polymers, such as, but not limited to, polyethylene terephthalate (PET), polyvinylidene fluoride (PVDF), polyamide (nylon), polyurethane, polycarbonate, polyester, polyetheretherketone (PEEK), polyethersulfone (PES), polyimide (PI), polyamide-imide, polyether, polyoxymethylene (e.g., acetal), polybutylene terephthalate, polyethylene naphthalate (polyethylene terephthalate). (Naphthenate), polybutene, polymethylpentene, polyolefin copolymers, acrylonitrile-butadiene-styrene copolymers (ABS), polystyrene copolymers, polymethyl methacrylate (PMMA), polysiloxane polymers (e.g., polydimethylsiloxane (PDMS)), polybenzimidazole (PBI), polybenzoxazole (PBO), polyphenylene, polyaryletherketone, polyperfluorocyclobutane, polyvinylidene fluoride copolymers (e.g., PVDF-hexafluoropropylene or (PVDF-HFP)), and polyvinylidene fluoride terpolymers, polyvinyl fluoride, liquid crystal polymers (e.g., VECTRANTM (Hoechst AG, Germany) and ZENITE® (DuPont, Wilmington, DE)), polyarylamides, polyphenylene ethers, cellulose materials, mesoporous silica, or combinations thereof.

[0103] Furthermore, the porous separator 26 may be mixed with a ceramic material, or its surface may be coated with a ceramic material. For example, the ceramic coating may include alumina (Al2O3), silicon dioxide (SiO2), or a combination thereof. Various commercially available polymers and products for forming the separator 26 are envisioned, as well as numerous manufacturing methods that may be employed to produce such separators.

[0104] current collector

[0105] Negative electrode 22 and positive electrode 24 are typically associated with corresponding negative electrode current collector 32 and positive electrode current collector 34 to facilitate electron flow between the electrodes and external circuitry 40. Current collectors 32 and 34 are conductive and can comprise metals such as metal foil, metal grids or mesh, or expanded metal. Expanded metal current collectors refer to metal grids with greater thickness, allowing a larger amount of electroactive material to be placed within the grid. Conductive materials include, by way of example, copper, nickel, aluminum, stainless steel, titanium, alloys thereof, or combinations thereof.

[0106] The positive electrode current collector 34 may be formed of aluminum or any other suitable conductive material known to those skilled in the art. The negative electrode current collector 32 may be formed of copper or any other suitable conductive material known to those skilled in the art. Aluminum is generally not included in the negative electrode current collector because aluminum reacts with lithium, causing large volume expansion and contraction. Drastic volume changes can lead to breakage and / or pulverization of the current collector.

[0107] Positive and negative electrodes

[0108] The positive electrode 24 may be formed of or comprise a lithium-based active material capable of undergoing lithium intercalation and deintercalation, alloying and dealloying, or deposition and stripping while serving as the positive terminal of the lithium-ion battery 20. The positive electrode 24 may comprise a positively active material. The positively active material may comprise one or more transition metal cations, such as manganese (Mn), nickel (Ni), cobalt (Co), chromium (Cr), iron (Fe), vanadium (V), and combinations thereof. However, in some variations, the positive electrode 24 substantially does not contain selected metal cations such as nickel (Ni) and cobalt (Co).

[0109] The negative electrode 22 may include a negatively active material as a lithium host material, which can serve as the negative terminal of the lithium-ion battery 20. Common negatively active materials include lithium-intercalated materials or alloy host materials. In some aspects, the negative electrode 22 includes metallic lithium, and the negative electrode 22 is a lithium metal electrode (LME). The lithium-ion battery 20 may be a lithium metal battery or a battery cell.

[0110] lithium metal batteries

[0111] Lithium metal, used in the negative electrode of rechargeable batteries, offers various potential advantages, including the highest theoretical capacity and the lowest electrochemical potential. Therefore, batteries incorporating lithium metal anodes can achieve higher energy densities, potentially doubling storage capacity and halving battery size while still providing the same duration as other lithium-ion batteries. However, the use of lithium metal electrodes also has potential drawbacks.

[0112] First, lithium metal is highly reactive. Therefore, unless stored and transported in an insert environment or in a vacuum, a passivation layer will form on the exposed surface of the lithium metal. By way of example, the passivation layer may include lithium oxide, lithium hydroxide, lithium nitride, lithium carbonate, organic matter, and / or oil. Passivation layers are generally undesirable because they can reduce the wettability of the electrolyte relative to the lithium metal electrode. Low wettability means a small contact angle between the electrolyte and the lithium metal electrode surface, and therefore tends to form discrete islands on the surface, resulting in reduced or poor electrolyte distribution. After polymerization, the electrolyte can generate large and uneven tension on the surface of the lithium metal electrode, which can reduce or prevent the formation of a solid electrolyte interface (SEI) and / or accelerate dendrite formation, subsequently leading to cell failure.

[0113] Secondly, lithium metal electrodes often exhibit high surface roughness, such as greater than or equal to about 500 nm. High surface roughness is generally undesirable because it can inhibit the formation of the SEI layer. The SEI layer can increase the cycle life of electrochemical cell cells including lithium metal electrodes by reducing or preventing the growth of lithium dendrites, and / or exhibit flexible properties that provide mechanical protection to the lithium metal electrode. Dendrites are dendritic or fibrous lithium metal structures that can grow on the electrode during cycling. Dendrites can form sharp protrusions that can pierce separators and potentially cause internal short circuits.

[0114] In various aspects, this disclosure provides a method for preparing a lithium metal electrode for an electrochemical battery cell. The method includes exposing a lithium metal electrode precursor having a passivation layer to a process gas to chemically and / or mechanically remove at least a portion of the passivation layer. The process gas may include reactants and / or plasma. The reactants may react with functional groups in the passivation layer to remove or replace the functional groups. The plasma may bombard the passivation layer to mechanically remove all or a portion of the passivation layer. In some aspects, the method may be performed in a single step (i.e., by injecting a single process gas without further processing).

[0115] The method disclosed herein is simple and scalable. In some aspects, the method can be performed at cryogenic temperatures, which reduce or prevent softening of the lithium metal electrode. In some aspects, such as when the process gas consists only of plasma, the method may include removing the passivation layer without depositing another layer onto the electrode. In some aspects, such as when the process gas includes reactants, the method may be tunable to obtain maximum compatibility (e.g., wettability) of the lithium metal electrode with the desired electrolyte. In some aspects, the method may be performed using commercially available atomic layer deposition (ALD) equipment, which facilitates tight control over temperature, pressure, and / or dosing. Compared to an untreated lithium metal electrode, the resulting lithium metal electrode may exhibit increased wettability, improved SEI layer quality, increased capacity retention, and increased cycle life.

[0116] refer to Figure 2 The method includes placing an electrode precursor 200 into a glove-type operating box or chamber 202. The electrode precursor 200 includes a lithium metal body 204 and a passivation layer 206. In some aspects, the chamber 202 may be part of a commercially available ALD device.

[0117] A first inlet 208, a second inlet 210, and an outlet 212 may be fluidly connected to a chamber 202. The first inlet 208 may be configured to inject (e.g., pulse) a reactant gas 214 into the chamber 202. The reactant gas 214 may be injected together with a carrier gas (such as argon or nitrogen). The second inlet 210 may be configured to inject a plasma precursor 216, which may also be referred to as a carrier gas. The plasma precursor 216 is heated to form plasma 218. The reactant gas 214 and plasma 218 may be collectively referred to as process gases. The first inlet 208 and / or the second inlet 210 may be provided at different locations. The outlet 212 may be configured to discharge a purge stream 220. The purge stream 220 may include excess reactants, reaction products / byproducts, excess plasma precursor, plasma, passivation layer particles removed from the chamber 202, and / or other residues.

[0118] The method includes introducing (e.g., injecting and / or forming) at least one process gas into chamber 202. The process gas may be configured to remove all or a portion of the passivation layer 206. In some aspects, the process gas may be configured to remove substantially the entire passivation layer 206. The process gas may include reactant gas 214, plasma 218, or both reactant gas 214 and plasma 218. When the process gas includes both reactant gas 214 and plasma 218, the process gas may be supplied sequentially (e.g., reactant gas 214 and then plasma 218, or plasma 218 and then reactant gas 214) or simultaneously. In some aspects, one of the first inlet 208 or the second inlet 210 may be omitted. In the example, the process gas (i.e., reactant gas 214 and / or plasma 218) is supplied in a discrete pulsed manner while outlet 212 remains constantly open.

[0119] The reactant gas 214 is configured to react with at least a portion of the passivation layer 206. For example, the reactant gas 214 may be configured to chemically react with functional groups (such as hydroxyl groups) in the passivation layer 206. This chemical reaction may cause the removal of functional groups from the passivation layer 206, thereby removing at least a portion of the passivation layer 206. In some aspects, the chemical reaction may cause the replacement of at least a portion of the functional groups with different functional groups. The reactant gas 214 may be selected such that the remaining functional groups are compatible with the desired electrolyte, such as by having a desired droplet contact angle and / or the ability to chemically bond with the desired electrolyte. In one example, the reactant gas 214, which includes hydroxyl functional groups, is replaced with aluminum oxide (Al₂O₃) functional groups. The Al-O bonds of the added functional groups are believed to promote the stability of the lithium metal surface. In some respects, the reactant gas 214 may be selected from the group consisting of: trimethylaluminum (TMA); trimethyl phosphate (TMPO), N2; H2O, O2, O3, triethyl phosphate (TEPO), titanium isopropoxide (TTIP), or any combination thereof.

[0120] By way of example, for each deposition cycle or pulse, reactant gas 214 may be supplied to chamber 202 in the following amounts: greater than or equal to about 1 standard cubic centimeter per minute (sccm), optionally greater than or equal to about 5 sccm, optionally greater than or equal to about 10 sccm, or optionally greater than or equal to about 15 sccm. By way of example, for each deposition cycle, reactant gas 214 may be supplied to chamber 202 in the following amounts: less than or equal to about 20 sccm, optionally less than or equal to about 15 sccm, optionally less than or equal to about 10 sccm, or optionally less than or equal to about 5 sccm. By way of example, for each deposition cycle, reactant gas 214 may be supplied to chamber 202 for the following durations: greater than or equal to about 100 ms, optionally greater than or equal to about 500 ms, optionally greater than or equal to about 1 s, or optionally greater than or equal to about 5 s. By way of example, for each deposition cycle, the duration may be less than or equal to about 10 s, optionally less than or equal to about 5 s, optionally less than or equal to about 1 s, or optionally less than or equal to about 500 ms. By way of example, the method may include multiple deposition cycles, such as greater than or equal to 1 cycle, optionally greater than or equal to about 5 cycles, optionally greater than or equal to about 10 cycles, optionally greater than or equal to about 20 cycles, optionally greater than or equal to about 30 cycles, optionally greater than or equal to about 40 cycles, optionally greater than or equal to about 50 cycles, optionally greater than or equal to about 60 cycles, optionally greater than or equal to about 70 cycles, optionally greater than or equal to about 80 cycles, optionally greater than or equal to about 90 cycles, or optionally greater than or equal to about 100 cycles. By way of example, in some aspects, the method may include less than or equal to about 100 deposition cycles, optionally less than or equal to about 90 cycles, optionally less than or equal to about 80 cycles, optionally less than or equal to about 70 cycles, optionally less than or equal to about 60 cycles, optionally less than or equal to about 50 cycles, optionally less than or equal to about 40 cycles, optionally less than or equal to about 30 cycles, optionally less than or equal to about 20 cycles, or optionally less than or equal to about 10 cycles.

[0121] Plasma 218 is configured to mechanically bond (e.g., bombard, impact) passivation layer 206 to remove at least a portion of passivation layer 206. In some aspects, plasma precursor 216 may be selected from the group consisting of Ar, O2, O3, N2, NH3, or any combination thereof. Plasma precursor 216 may be heated (e.g., electrically heated) to form plasma 218. In some aspects, plasma 218 may be formed in a pulsed manner.

[0122] By way of example, for each deposition cycle or pulse, plasma precursor 216 may be supplied to chamber 202 in the following amounts: greater than or equal to about 10 sccm, optionally greater than or equal to about 20 sccm, optionally greater than or equal to about 30 sccm, optionally greater than or equal to about 40 sccm, optionally greater than or equal to about 50 sccm. By way of example, for each deposition cycle, plasma precursor 216 may be supplied to chamber 202 in the following amounts: less than or equal to about 60 sccm, optionally less than or equal to about 50 sccm, optionally less than or equal to about 40 sccm, optionally less than or equal to about 30 sccm, or optionally less than or equal to about 20 sccm. By way of example, for each deposition cycle, plasma precursor 216 may be supplied to chamber 202 for the following durations: greater than or equal to about 100 ms, optionally greater than or equal to about 500 ms, optionally greater than or equal to about 1 s, or optionally greater than or equal to about 5 s. By way of example, for each deposition cycle, the duration may be less than or equal to about 10 s, optionally less than or equal to about 5 s, optionally less than or equal to about 1 s, or optionally less than or equal to about 500 ms. By way of example, the method may include multiple deposition cycles, such as greater than or equal to 1 cycle, optionally greater than or equal to about 5 cycles, optionally greater than or equal to about 10 cycles, optionally greater than or equal to about 20 cycles, optionally greater than or equal to about 30 cycles, optionally greater than or equal to about 40 cycles, optionally greater than or equal to about 50 cycles, optionally greater than or equal to about 60 cycles, optionally greater than or equal to about 70 cycles, optionally greater than or equal to about 80 cycles, optionally greater than or equal to about 90 cycles, or optionally greater than or equal to about 100 cycles. By way of example, in some aspects, the method may include less than or equal to about 100 deposition cycles, optionally less than or equal to about 90 cycles, optionally less than or equal to about 80 cycles, optionally less than or equal to about 70 cycles, optionally less than or equal to about 60 cycles, optionally less than or equal to about 50 cycles, optionally less than or equal to about 40 cycles, optionally less than or equal to about 30 cycles, optionally less than or equal to about 20 cycles, or optionally less than or equal to about 10 cycles.

[0123] The environmental conditions of chamber 202 can be strictly controlled. By way of example, in some aspects, the pressure inside chamber 202 may be greater than or equal to about 100 mTorr, optionally greater than or equal to about 500 mTorr, optionally greater than or equal to about 1 mTorr, or optionally greater than or equal to about 2 mTorr. The pressure may be less than or equal to about 5 Torr, optionally less than or equal to about 2 Torr, optionally less than or equal to about 1 Torr, or optionally less than or equal to about 500 mTorr. In some aspects, chamber 202 may be substantially airless.

[0124] In some aspects, the electrode precursor 200 may be disposed on a temperature control station 222. The temperature control station 222 may be configured to heat the electrode precursor 200. In some aspects, the station 222 may be controlled to heat the electrode precursor 200 to a temperature greater than or equal to about 20°C, optionally greater than or equal to about 30°C, optionally greater than or equal to about 40°C, optionally greater than or equal to about 50°C, optionally greater than or equal to about 60°C, optionally greater than or equal to about 70°C, or optionally greater than or equal to about 80°C. The temperature may be less than about 90°C, optionally less than or equal to about 80°C, optionally less than or equal to about 70°C, optionally less than or equal to about 60°C, optionally less than or equal to about 50°C, optionally less than or equal to about 40°C, or optionally less than or equal to about 30°C. In the example, the temperature is greater than or equal to about 60°C to less than or equal to about 70°C. In other aspects, the method may be performed at room temperature or about 23°C.

[0125] In some aspects, the method may further include positioning an electrolyte in contact with the surface of a lithium metal electrode. The electrolyte may be disposed on the lithium metal electrode outside the chamber. The electrolyte may include a liquid electrolyte or a gel polymer electrolyte. In some aspects, when the electrolyte is a gel polymer electrolyte, the method may include depositing a layer comprising monomers and an initiator on the surface of the electrode. The method may further include crosslinking the monomers to form the gel polymer electrolyte, such as by exposing the layer to heat and / or UV radiation.

[0126] In various aspects, this disclosure provides a lithium metal electrode. This lithium metal electrode can be configured according to... Figure 2 The method discussed is used to form the lithium metal electrode, which can be formed with virtually no passivation layer (see example). Figure 3 The electrode 300 has a passivation layer that has been at least partially mechanically or chemically removed, and / or has a passivation layer that has been chemically modified (see example...). Figure 4 Electrode 400).

[0127] refer to Figure 3A lithium metal electrode 300 is provided according to various aspects of this disclosure. The lithium metal electrode 300 includes a lithium metal body 204. The lithium metal body 204 includes a surface 302. The surface 302 may be substantially without a passivation layer. Therefore, the surface 302 may include lithium metal. In some aspects, the surface 302 may be substantially composed of lithium metal.

[0128] refer to Figure 4 A lithium metal electrode 400 is provided according to various aspects of this disclosure. The lithium metal electrode 400 includes a lithium metal body 204 and a passivation layer 402. The passivation layer 402 is chemically different from... Figure 2 The passivation layer 206 of the electrode precursor 200, such as having fewer, different, and / or additional functional groups. In some aspects, the added functional groups can be configured to chemically bond with the electrolyte to produce improved interfacial dynamics between the electrolyte and the electrode 400. In the example, with the passivation layer 206 ( Figure 2 Compared to passivation layer 206, passivation layer 402 includes fewer hydroxyl functional groups. In another example, compared to passivation layer 206, passivation layer 402 includes fewer hydroxyl functional groups and fewer carbonate functional groups.

[0129] In various respects, this disclosure provides a lithium metal electrode assembly. (Reference) Figure 5 The present disclosure provides a lithium metal electrode assembly 500 according to various aspects thereof. The lithium metal electrode assembly 500 includes a lithium metal electrode 300 (or another lithium metal electrode prepared according to the principles of the present disclosure) and an electrolyte 502. The electrolyte may be a gel polymer electrolyte or a liquid electrolyte.

[0130] Gel polymer electrolytes may include a polymer matrix (e.g., PEO, PMMA, and / or polymethyl methacrylate (PMA)), a solvent / plasticizer (e.g., EC, EMC), and a lithium salt (e.g., LiPF6, LiTFSI). In some aspects, the liquid electrolyte may have a viscosity greater than or equal to about 0.5 cP, optionally greater than or equal to about 1 cP, or optionally greater than or equal to about 10 cP. In some aspects, the liquid electrolyte may include a salt of a selected solvent, such as those described above. Figure 1 Those described in the discussion. For example, solvents may include EC and / or EMC, and salts may include LiPF6 and / or LiTFSI.

[0131] In some respects, the electrolyte may have high wettability relative to the electrode surface. As used herein, wettability is the attractive force of the electrolyte to the electrode surface. Therefore, an electrolyte with high wettability can have a small contact angle with the surface, causing it to tend to diffuse and distribute across the surface rather than form discrete islands. The contact angle is the angle formed between the surface of the electrode and a line tangent to the edge of the electrolyte droplet. In some respects, the contact angle is greater than or equal to about 0°, optionally greater than or equal to about 10°, optionally greater than or equal to about 20°, optionally greater than or equal to about 30°, optionally greater than or equal to about 40°, optionally greater than or equal to about 50°, optionally greater than or equal to about 60°, optionally greater than or equal to about 70°, or optionally greater than or equal to about 80°. By way of example, the contact angle may be less than or equal to about 90°, optionally less than or equal to about 80°, optionally less than or equal to about 70°, optionally less than or equal to about 60°, optionally less than or equal to about 50°, optionally less than or equal to about 40°, optionally less than or equal to about 30°, optionally less than or equal to about 20°, or optionally less than or equal to about 10°.

[0132] In various respects, electrode 300 is a negative electrode, and electrode assembly 500 can be included in an electrochemical cell unit having a positive electrode, a separator, and a current collector, such as in an accompanying... Figure 1 The positive electrodes include those described in the discussion. Positive electrodes include positively active materials such as lithium nickel manganese cobalt oxide (NMC) (e.g., NMC622 and / or NMC811) and / or aluminum-doped NMC (NMCA).

[0133] As discussed above, an electrochemical cell including electrode assembly 500 may have improved performance compared to an electrochemical cell including an untreated lithium metal electrode. For example, improved performance may include improved areal capacity, improved cycle life, and / or capacity retention. By way of example, in some aspects, the areal discharge capacity of an electrochemical cell including electrode assembly 500 may be greater than or equal to about 1 mAh / cm³. 2 Optionally greater than or equal to about 1.5 mAh / cm³ 2 Optionally greater than or equal to about 2 mAh / cm 2 Optionally greater than or equal to about 2.5 mAh / cm³ 2 Optionally greater than or equal to about 3 mAh / cm³ 2 Optionally greater than or equal to approximately 3.5 mAh / cm³ 2 Optionally greater than or equal to about 4 mAh / cm³ 2 Or optionally greater than or equal to about 4.5 mAh / cm³ 2 As an example, the surface discharge capacity can be less than or equal to about 5 mAh / cm³.2 Optionally less than or equal to about 4.5 mAh / cm³ 2 Optionally less than or equal to about 4 mAh / cm³ 2 Optionally less than or equal to about 3.5 mAh / cm³ 2 Optionally less than or equal to about 3 mAh / cm³ 2 Optionally less than or equal to about 2.5 mAh / cm³ 2 Optionally less than or equal to about 2 mAh / cm³ 2 Or optionally less than or equal to about 1.5 mAh / cm³ 2 By way of example, in some aspects, after approximately 100 cycles, the electrochemical cell cell including electrode assembly 500 may have a discharge capacity retention rate of: greater than or equal to approximately 60%, optionally greater than or equal to approximately 65%, optionally greater than or equal to approximately 70%, optionally greater than or equal to approximately 75%, optionally greater than or equal to approximately 80%, optionally greater than or equal to approximately 85%, optionally greater than or equal to approximately 90%, or optionally greater than or equal to approximately 92%. By way of example, after approximately 100 cycles, the discharge capacity retention rate may be less than or equal to approximately 100%, optionally less than or equal to approximately 95%, optionally less than or equal to approximately 90%, optionally less than or equal to approximately 85%, optionally less than or equal to approximately 80%, optionally less than or equal to approximately 75%, optionally less than or equal to approximately 70%, or optionally less than or equal to approximately 65%.

[0134] Example 1 – Wettability of lithium metal treated with reactants

[0135] refer to Figure 6 A first sample 600 is prepared. The first sample 600 comprises lithium metal. The first sample 600 is untreated. Therefore, the first surface 602 of the first sample is considered to include a passivation layer. A second sample 610 is prepared according to various aspects of this disclosure. The second sample 610 is pretreated with TMA, which is injected together with an argon carrier gas. The chamber temperature is greater than or equal to about 20°C and less than or equal to about 50°C. The chamber pressure is about 250 mTorr. The pulse duration is about 500 ms and the pulse rate is about 10 sccm. 30 pulses / cycle are performed. The TMA is considered to react with at least a portion of the hydroxyl groups and / or carbonate groups in the passivation layer. Therefore, the second sample 610 has a modified passivation layer on the second surface 612.

[0136] The contact angles of the first sample 600 and the second sample 610 were observed by placing droplets of the gel electrolyte precursor liquid onto each of the first sample 600 and the second sample 610. The gel electrolyte precursor comprises 5% by weight PMMA and 1 M LiPF6 in EC / EMC. More specifically, a first droplet 620 is disposed on a first surface 602 of the first sample 600, and a second droplet 622 is disposed on a second surface 612 of the second sample 610. The contact angle of the second droplet 622 is greater than that of the first droplet 620. Therefore, the second sample 610 exhibits greater wettability to the electrolyte compared to the first sample 600. Thus, TMA pretreatment is effective in improving the wettability of the lithium metal electrode.

[0137] Example 2 – Wettability of plasma-treated lithium metal

[0138] refer to Figure 7 A first sample 700 is prepared. The first sample 700 comprises lithium metal. The first sample 700 is untreated. Therefore, the first surface 702 of the first sample is considered to include a passivation layer. A second sample 710 is prepared according to various aspects of this disclosure. The second sample 710 is pretreated with argon plasma. The chamber temperature is greater than or equal to about 20°C and less than or equal to about 50°C. The chamber pressure is about 250 mTorr. The pulse duration is about 5 seconds and the pulse rate is about 10 sccm. 30 pulses / cycle are performed. The plasma is considered to bind the passivation layer to mechanically remove at least a portion of the passivation layer. Therefore, the second sample 710 has a reduced or removed passivation layer on the second surface 712.

[0139] The contact angles of the first sample 700 and the second sample 710 were observed by placing droplets of the gel electrolyte precursor onto each of the first sample 700 and the second sample 710. The gel electrolyte precursor comprises 5 wt% PMMA and 1 M LiPF6 in EC / EMC. More specifically, a first droplet 720 is disposed on a first surface 702 of the first sample 700, and a second droplet 722 is disposed on a second surface 712 of the second sample 710. The second droplet 722 diffuses across the second surface 712. The contact angle of the second droplet 722 is much larger than that of the first droplet 720. Therefore, the second sample 710 has a much greater wettability to the electrolyte compared to the first sample 700. Therefore, plasma pretreatment is effective in improving the wettability of the lithium metal electrode.

[0140] Example 3 – Cyclic Performance

[0141] Three lithium metal batteries were fabricated. Each of these three lithium metal batteries contains 4.2 mAh / cm³. 2An NMC-622 positive electrode; a PMMA-based gel electrolyte comprising an EX / EMC solvent and a LiPF6 salt; and a polyethylene separator. A first lithium metal battery includes an untreated lithium metal negative electrode. A second lithium metal battery includes a TMA-treated (reactant-treated) lithium metal electrode prepared according to the method described in Example 1 above. A third lithium metal battery includes a plasma-treated lithium metal electrode prepared according to the method described in Example 2 above.

[0142] Each of these three lithium-metal batteries was cycled at 3–4.3 V and 0.1 CC–0.5 CD. (Reference) Figure 8 The graph depicts the cycle performance of three lithium-metal batteries. The x-axis (800) represents cycles. The y-axis (802) represents capacity in mAh. Curve 804 represents the performance of the first lithium-metal battery. Curve 806 represents the performance of the second lithium-metal battery. Curve 808 represents the performance of the third lithium-metal battery. The first lithium-metal battery experiences significant capacity decay after approximately 95 cycles, as shown at 910, and fails at approximately 102 cycles, as shown at 912. The second lithium-metal battery begins to experience a more gradual capacity decay (compared to the first lithium-metal battery) after approximately 100 cycles, as shown at 814, and cycles through approximately 160 cycles, as shown at 816. The third lithium-metal battery begins to experience a more gradual capacity decay (compared to the first and second lithium-metal batteries) after approximately 105 cycles, as shown at 818, and cycles through approximately 160 cycles, as shown at 820. Therefore, the second and third lithium metal batteries (which include pretreated lithium metal negative electrodes) are able to undergo more cycles than untreated lithium metal electrodes. Furthermore, the second and third lithium metal batteries experience greater capacity retention than the first lithium metal battery, especially after approximately 95 cycles.

[0143] The foregoing description is merely illustrative in nature and is not intended in any way to limit this disclosure, its application, or use. The broad teachings of this disclosure can be implemented in various forms. Therefore, while this disclosure includes specific examples, its true scope should not be so limited, as other modifications will become apparent upon examination of the drawings, specification, and the following claims. It should be understood that one or more steps within a method may be performed in a different order (or simultaneously) without altering the principles of this disclosure. Furthermore, although each of the embodiments described above is characterized by certain features, any one or more of those features described with respect to any embodiment of this disclosure can be implemented in any other embodiment and / or combined with features of any other embodiment, even if such combination is not explicitly described. In other words, the described embodiments are not mutually exclusive, and permutations and combinations of one or more embodiments with each other remain within the scope of this disclosure.

Claims

1. A method for preparing a lithium metal electrode for use in an electrochemical battery cell, the method comprising: Processing gas is introduced into a chamber containing an electrode precursor, which includes lithium metal and a passivation layer; as well as The lithium metal electrode is formed by contacting the processing gas with the passivation layer to remove at least a portion of the passivation layer. The processing gas is a reactant configured to react with at least a portion of the passivation layer.

2. The method according to claim 1, wherein, The processing gas is a single processing gas.

3. The method according to claim 1, wherein, The reactants are configured to react with at least a portion of the passivation layer to alter the composition of the passivation layer.

4. The method according to claim 1, wherein, The reactants are selected from the group consisting of: trimethylaluminum (TMA); trimethyl phosphate (TMPO); nitrogen (N2); water (H2O); oxygen (O2); ozone (O3); triethyl phosphate (TEPO); titanium isopropoxide (TTIP); or any combination thereof.

5. The method according to claim 1, wherein, The reactant is configured to react with at least a portion of the passivation layer to replace functional groups on the surface of the lithium metal electrode.

6. The method according to claim 1, wherein, The processing gas is plasma, which is configured to mechanically bond with the passivation layer to remove at least a portion of the passivation layer.

7. The method according to claim 6, wherein, The introduction includes generating the plasma from a compound selected from the group consisting of: Ar, O2, O3, N2, NH3, or any combination thereof.

8. The method according to claim 1, wherein, The indoor temperature is greater than or equal to 20°C and less than or equal to 90°C.

9. The method according to claim 1, wherein, The room was essentially airless.

10. The method according to claim 1, wherein, The processing gas includes a first processing gas comprising reactants; and a second processing gas comprising plasma.

11. The method according to claim 1, wherein, The lithium metal electrode is configured to be in direct contact with the gel polymer electrolyte.

12. The method according to claim 1, wherein, The lithium metal electrode is configured to be in direct contact with a liquid electrolyte having a viscosity greater than or equal to 0.5 cP.

13. The method according to claim 1, wherein, The surface of the lithium metal electrode is configured to have a contact angle with the electrolyte of greater than or equal to 0° and less than or equal to 90°.

14. The method according to claim 1, wherein, The electrochemical assembly including the lithium metal electrode is configured to have a capacity greater than or equal to 1 mAh / cm². 2 to less than or equal to 5 mAh / cm 2 Surface discharge capacity.

15. A method for preparing a lithium metal electrode assembly for use in an electrochemical battery cell, the method comprising: Processing gas is introduced into a chamber containing an electrode precursor, which includes lithium metal and a passivation layer; The processing gas is brought into contact with the passivation layer to remove at least a portion of the passivation layer; as well as The electrolyte is configured to be in direct contact with the surface of the lithium metal electrode. The processing gas is a reactant configured to react with at least a portion of the passivation layer.

16. The method according to claim 15, wherein, The electrolyte is a gel polymer electrolyte.

17. The method according to claim 16, wherein, The electrolyte configuration includes: A layer is disposed on the surface, the layer comprising a monomer and an initiator. The monomers are crosslinked by exposing the layer to UV radiation to form the gel polymer electrolyte.

18. The method according to claim 15, wherein, The electrolyte is a liquid electrolyte with a viscosity greater than or equal to 0.5 cP.

19. A lithium metal battery, comprising: Positive electrode, which includes positively charged active material; A pretreated lithium metal electrode is formed by contacting a process gas with a passivation layer on an electrode precursor to remove at least a portion of the passivation layer, wherein the process gas is a reactant configured to react with at least a portion of the passivation layer; and An electrolyte that is in direct contact with the pretreated lithium metal electrode, said electrolyte comprising one of the following: (i) Gel polymer electrolyte, or (ii) A liquid electrolyte having a viscosity greater than or equal to 0.5 cP; and A separator between the positive electrode and the pretreated lithium metal electrode, the separator being ion-conducting and electrically insulating, wherein: The pretreated lithium metal electrode is configured to have a contact angle with the electrolyte of greater than or equal to 0° and less than or equal to 90°, and The lithium metal battery is configured to have a capacity greater than or equal to 1 mAh / cm³. 2 to less than or equal to 5 mAh / cm 2 Surface discharge capacity.

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