Electrodes comprising a polymeric binder network with bamboo-type fibers

Abstract

Electrodes including a polymer binder network having bamboo-type fibers are disclosed. The disclosure provides electrodes for electrochemical cells. The electrodes include a polymer binder network and a plurality of electroactive material particles. The polymer binder network includes a plurality of fibers defining the polymer binder network. The plurality of fibers each include a plurality of beads and a plurality of filaments. The plurality of filaments respectively extend from at least a portion of the plurality of beads. The plurality of electroactive material particles are in voids of the polymer binder network. In certain aspects, the disclosure provides single-sided or double-sided electrode assemblies including a current collector and an electrode.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to electrodes for electrochemical cells, electrode assemblies, and methods of making electrodes for electrochemical cells. BACKGROUND

[0002] The information provided in this section is presented to summarize the background of the present disclosure. The work of the present inventors in this regard, to the extent it is disclosable, as well as the descriptions of descriptions at the time of filing, are not, in and of themselves, prior art to the present disclosure.

[0003] The present disclosure relates to electrodes (e.g., for electrochemical cells) that include a polymer binder network comprising bamboo-type fibers.

[0004] Electrodes for lithium ion batteries or cells can have a high loading density of electroactive materials to increase overall cell energy density. For example, thicker layers of electroactive materials and / or greater loading of electroactive materials increase the relative amount of electroactive materials relative to inert materials (e.g., current collectors and separators) present in the electrochemical cell. However, performance of thick electrodes can be hindered, for example, by limited lithium ion channels between the electrolyte and / or the electroactive material, physical-chemical changes of the polymer binder during solvent evaporation. SUMMARY

[0005] In various aspects, the present disclosure provides electrodes for electrochemical cells. The electrodes include a polymer binder network and a plurality of electroactive material particles. The polymer binder network includes a plurality of fibers defining the polymer binder network. The plurality of fibers each include a plurality of beads and a plurality of filaments. The plurality of filaments each extend from at least a portion of the plurality of beads. The plurality of electroactive material particles are in interstices of the polymer binder network.

[0006] In an aspect, the plurality of fibers each include a plurality of segments. The plurality of segments each include a first portion and a second portion. The first portion includes the plurality of beads. The second portion includes the plurality of filaments.

[0007] In an aspect, the plurality of segments each define a length greater than or equal to about 0.1 μm to less than or equal to about 50 μm.

[0008] In an aspect, the plurality of segments each include a substantially cylindrical wall defining an interior region. The substantially cylindrical wall includes a first portion including the plurality of beads and a second portion including the plurality of filaments.

[0009] In an aspect, the substantially cylindrical wall defines a diameter greater than or equal to about 0.1 μm to less than or equal to about 500 μm.

[0010] In an aspect, the plurality of fibers each define a length greater than or equal to about 5 μιη to less than or equal to about 2 cm.

[0011] In an aspect, the plurality of beads each define a diameter greater than or equal to about 10 nm to less than or equal to about 1 μιη. The plurality of filaments each define a diameter greater than or equal to about 1 nm to less than or equal to about 300 nm.

[0012] In an aspect, the electrode defines a thickness greater than or equal to about 100 μιη to less than or equal to about 2 mm.

[0013] In an aspect, the polymeric binder network is present in an amount greater than or equal to about 0.3 wt% to less than or equal to about 10 wt%.

[0014] In an aspect, the electrode has an area specific capacity greater than or equal to about 4 mAh / cm 2 to less than or equal to about 50 mAh / cm 2 .

[0015] In an aspect, (i) the plurality of electroactive material particles comprise a positive electroactive material and the electrode has a press density greater than or equal to about 2 g / cm 3 to less than or equal to about 4 g / cm 3 , or (ii) the plurality of electroactive material particles comprise a negative electroactive material and the electrode has a press density greater than or equal to about 1 g / cm 3 to less than or equal to about 3 g / cm 3 .

[0016] In an aspect, the electrode defines a porosity greater than or equal to about 25 vol% to less than or equal to about 60 vol%.

[0017] In an aspect, at least a portion of the plurality of beads are configured to be fibrillated during cycling of an electrochemical cell comprising the electrode.

[0018] In an aspect, the polymeric binder network comprises polytetrafluoroethylene (PTFE).

[0019] In an aspect, the electrode further comprises a conductive material.

[0020] In an aspect, the plurality of electroactive material particles includes one of: (i) a positive electroactive material selected from: olivine compounds, rock salt, cobalt-free layered oxides, rock salt layered oxides, spinel, olivine, borates, silicates, organic compounds, sulfur, or any combination thereof, or (ii) a negative electroactive material selected from: carbonaceous materials, lithium-containing materials, tin-containing materials, lithium titanium oxides, metal oxides, metal sulfides, silicon-containing materials, lithiated silicon-containing materials, or any combination thereof.

[0021] In various aspects, the disclosure provides an electrode assembly. The electrode assembly includes a current collector and an electrode layer. The current collector includes an electrically conductive material. The electrode layer is on the current collector. The electrode layer includes a polymeric binder network and a plurality of electroactive material particles. The polymeric binder network includes a plurality of fibers. The plurality of fibers defines the polymeric binder network. The plurality of fibers each includes a plurality of beads and a plurality of filaments. The plurality of filaments each extends from at least a portion of the plurality of beads. The plurality of electroactive material particles are in interstices of the binder polymeric network.

[0022] In an aspect, the current collector includes a web, and the electrode layer is in direct contact with the web.

[0023] In an aspect, the electrode assembly further includes an electrically conductive binder between the current collector and the electrode layer.

[0024] In various aspects, the disclosure provides a method of manufacturing an electrode for an electrochemical cell. The method includes preparing a mixture by mixing a plurality of electroactive material particles with a plurality of polymeric binder fibers. The plurality of polymeric binder fibers each includes a plurality of beads and a plurality of filaments extending from at least a portion of the plurality of beads. The method further includes depositing the mixture onto a substrate. The method further includes pre-rolling the mixture on the substrate to form a film precursor including the mixture and defining a first thickness. The method further includes forming the electrode by final-rolling the film precursor to define a second thickness that is less than the first thickness.

[0025] The following embodiments are disclosed:

[0026] 1. An electrode for an electrochemical cell, comprising:

[0027] a polymeric binder network, comprising:

[0028] a plurality of fibers defining the polymeric binder network, the plurality of fibers each comprising:

[0029] a plurality of beads, and

[0030] a plurality of filaments each extending from at least a portion of the plurality of beads; and

[0031] a plurality of electroactive material particles in interstices of the polymeric binder network.

[0032] 2. The electrode of embodiment 1, wherein

[0033] each of the plurality of fibers comprises a plurality of segments, and

[0034] each of the plurality of segments comprises

[0035] a first portion comprising a plurality of beads, and

[0036] a second portion comprising a plurality of filaments.

[0037] 3. The electrode of embodiment 2, wherein each of the plurality of segments defines a length greater than or equal to about 0.1 pm to less than or equal to about 50 pm.

[0038] 4. The electrode of embodiment 2, wherein

[0039] each of the plurality of segments comprises a substantially cylindrical wall defining an interior region, and

[0040] the substantially cylindrical wall comprises

[0041] a first portion comprising a plurality of beads, and

[0042] a second portion comprising a plurality of filaments.

[0043] 5. The electrode of embodiment 4, wherein the substantially cylindrical wall defines a diameter greater than or equal to about 0.1 pm to less than or equal to about 500 pm.

[0044] 6. The electrode of embodiment 1, wherein each of the plurality of fibers defines a length greater than or equal to about 5 pm to less than or equal to about 2 cm.

[0045] 7. The electrode of embodiment 1, wherein

[0046] each of the plurality of beads defines a diameter greater than or equal to about 10 nm to less than or equal to about 1 pm, and

[0047] each of the plurality of filaments defines a diameter greater than or equal to about 1 nm to less than or equal to about 300 nm.

[0048] 8. The electrode of embodiment 1, wherein the electrode defines a thickness greater than or equal to about 100 pm to less than or equal to about 2 mm.

[0049] 9. The electrode of embodiment 1, wherein the polymeric binder network is present at greater than or equal to about 0.3 wt% to less than or equal to about 10 wt%.

[0050] 10. The electrode of embodiment 1, wherein the electrode has an area specific capacity greater than or equal to about 4 mAh / cm 2 to less than or equal to about 50 mAh / cm 2 .

[0051] 11. The electrode of embodiment 1, wherein

[0052] (i) the plurality of electroactive material particles comprise a positive electroactive material, and the electrode has a compacted density greater than or equal to about 2 g / cm 3 to less than or equal to about 4 g / cm 3 , or

[0053] (ii) the plurality of electroactive material particles comprise a negative electroactive material, and the electrode has a compacted density greater than or equal to about 1 g / cm 3 to less than or equal to about 3 g / cm 3 .

[0054] 12. The electrode of embodiment 1, wherein the electrode defines a porosity greater than or equal to about 25 vol% to less than or equal to about 60 vol%.

[0055] 13. The electrode of embodiment 1, wherein at least a portion of the plurality of beads are configured to be fibrillated during cycling of an electrochemical cell comprising the electrode.

[0056] 14. The electrode of embodiment 1, wherein the polymeric binder network comprises polytetrafluoroethylene (PTFE).

[0057] 15. The electrode of embodiment 1, further comprising:

[0058] a conductive material.

[0059] 16. The electrode of embodiment 1, wherein the plurality of electroactive material particles comprise one of:

[0060] (i) a positive electroactive material selected from the group consisting of: olivine compounds, rock salt, cobalt-free layered oxides, rock salt layered oxides, spinels, olivine, borates, silicates, organic compounds, sulfur, or any combination thereof, or

[0061] (ii) a negative electroactive material selected from the group consisting of: carbonaceous materials, lithium-containing materials, tin-containing materials, lithium titanium oxides, metal oxides, metal sulfides, silicon-containing materials, lithiated silicon-containing materials, or any combination thereof.

[0062] 17. An electrode assembly comprising:

[0063] a current collector comprising an electrically conductive material; and

[0064] an electrode layer on the current collector, the electrode layer comprising:

[0065] a polymeric binder network comprising:

[0066] a plurality of fibers defining the polymeric binder network, the plurality of fibers each comprising:

[0067] a plurality of beads, and

[0068] a plurality of filaments extending from at least a portion of the plurality of beads, respectively; and

[0069] a plurality of electroactive material particles in voids of the binder polymeric network.

[0070] 18. The electrode assembly of embodiment 17, wherein the current collector comprises a mesh, and the electrode layer is in direct contact with the mesh.

[0071] 19. The electrode assembly of embodiment 17, further comprising:

[0072] an electrically conductive binder between the current collector and the electrode layer.

[0073] 20. A method of manufacturing an electrode for an electrochemical cell, the method comprising:

[0074] preparing a mixture by mixing a plurality of electroactive material particles with a plurality of polymeric binder fibers, the plurality of polymeric binder fibers each comprising a plurality of beads and a plurality of filaments extending from at least a portion of the plurality of beads;

[0075] depositing the mixture onto a substrate;

[0076] pre-rolling the mixture on the substrate to form a film precursor comprising the mixture and defining a first thickness; and

[0077] forming the electrode by final-rolling the film precursor to define a second thickness that is less than the first thickness.

[0078] Other suitable areas of applicability of the present disclosure will become apparent from the detailed description, claims, and drawings. The detailed description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. BRIEF DESCRIPTION OF DRAWINGS

[0079] The present disclosure will become more fully understood from the detailed description, the accompanying drawings, and the appended claims.

[0080] Figure 1 is a schematic illustration of an electrochemical cell for the cycling of lithium ions;

[0081] Figure 2 is a schematic illustration of an electrode assembly for an electrochemical cell according to various aspects of the present disclosure;

[0082] Figure 3 is a schematic illustration of another electrode assembly for an electrochemical cell according to various aspects of the present disclosure;

[0083] Figure 4 is a partial schematic illustration of an electrode including a polymeric binder network, electroactive material particles, and a conductive material according to various aspects of the present disclosure;

[0084] Figure 5 is a schematic illustration of a fiber of a polymeric binder network of Figure 4

[0085] Figure 6 is a partial perspective view of a wall of a fiber of Figure 5

[0086] Figure 7 is a scanning electron microscope image of a portion of a plurality of polymeric binder fibers according to various aspects of the present disclosure;

[0087] Figure 8 is a flowchart depicting a method of manufacturing an electrode according to the principles of the present invention; and

[0088] Figure 9 is an exemplary embodiment of a method of Figure 8

[0089] In the drawings, reference numerals can be repeated among the figures for like and / or identical elements. DETAILED DESCRIPTION

[0090] The exemplary embodiments are provided so that this disclosure will be thorough, and will fully convey the scope to those who come to this disclosure. Numerous specific details are set forth such as examples of specific components, devices, and methods, to provide a thorough understanding of embodiments of the present disclosure. It will be apparent to those skilled in the art that specific details need not be employed, that exemplary embodiments can be embodied in many different forms and that neither should be construed to limit the scope of the disclosure. In some exemplary embodiments, well-known methods, well-known device structures, and well-known technologies are not described in detail.

[0091] ​​​The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting. As used herein, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms "comprises," "comprising," "includes," "including," "contains," "containing," and "has," "having," are inclusive and therefore specify the presence of stated features, integers, compositions, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, compositions, steps, operations, elements, components, and / or groups thereof. Although the open-ended term "comprising," is to be understood as a non-limiting term used to describe and claim various embodiments set forth herein, in certain aspects, the term or can be understood to be the more restrictive and limiting term "consisting of or "consisting essentially of in some aspects. Accordingly, the disclosure also specifically includes embodiments in which the recited compositions, materials, components, elements, features, integers, operations, and / or method steps are "consisting of or "consisting essentially of such recited compositions, materials, components, elements, features, integers, operations, and / or method steps, as the case can be. In the case of "consisting of, alternative embodiments are ruled out that include any additional compositions, materials, components, elements, features, integers, operations, and / or method steps, while in the case of "consisting essentially of, any additional compositions, materials, components, elements, features, integers, operations, and / or method steps that do not materially affect the basic and novel characteristic(s) are excluded from such embodiments, but any compositions, materials, components, elements, features, integers, operations, and / or method steps that do materially affect the basic and novel characteristic(s) can be included in the embodiments.

[0092] Any method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order in which they are described, unless specifically identified as an order of performance. It is also to be understood that additional or alternative steps can be employed, unless otherwise specifically noted.

[0093] When an element or layer is referred to as being "on," "engaged," "connected," or "coupled" to another element or layer, it can be directly on, engaged, connected, or coupled to the other element or layer, or one or more intervening elements or layers can be present. In contrast, when an element is referred to as being "directly on," "directly engaged," "directly connected," or "directly coupled" to another element or layer, there are no intervening elements or layers present. Other words used to describe the relationship between elements should be interpreted in a like fashion (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.

[0094] Although the terms first, second, third, etc. can 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. These terms can be only used to distinguish one step, element, component, region, layer or section from another step, element, component, region, layer or section. Terms such as "first", "second", and other numerical terms when used herein do not imply a sequence or order unless clearly indicated by the context. Thus, a first step, element, component, region, layer or section discussed below could be termed a second step, element, component, region, layer or section without departing from the teachings of the example embodiments.

[0095] For ease of description, spatial or temporal terms, such as "front", "back", "inner", "outer", "under", "below", "lower", "above", "upper", and the like, can be used herein for describing one element or feature's relationship to another element or feature(s) as illustrated in the figures. The spatial or temporal terms can be intended to encompass different orientations of the device or system in use or operation, in addition to the orientations depicted in the figures.

[0096] Throughout this disclosure, numerical values represent approximate measurements or range limits to encompass slight deviations and embodiments substantially having the recited value as well as embodiments having the recited value exactly. Except in the working examples provided at the end of the detailed description, all numerical values in this specification (including the appended claims) that are by way of example only and can include a tolerance of up to 10% around the stated value, unless otherwise indicated in the specific context. "Approximately" means that slight deviations are allowed (an exact value is approached; is approximately or reasonably close to; is nearly). If the inaccuracy provided by "approximately" is not otherwise understood in the art to have this ordinary meaning, then "approximately" as used herein means at least the inaccuracy that can result from ordinary methods of measuring and using such parameters. For example, "approximately" can include an inaccuracy 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 certain aspects, optionally less than or equal to 0.1%.

[0097] Furthermore, the disclosure of a range includes all values and further subdivisions between and within that range; including the endpoints given by the range and the subranges.

[0098] The example embodiments will now be described more fully with reference to the accompanying drawings.

[0099] The present technology relates to rechargeable lithium-ion battery packs that can be used in vehicle applications. However, the present technology can also be used in other electrochemical devices that cycle lithium ions, such as handheld electronic devices or energy storage systems (ESS).

[0100] General electrochemical cell function, structure and composition

[0101] As background, an exemplary and schematic illustration of an electrochemical cell (also referred to as a battery) 20 is shown in Figure 1 The skilled artisan will appreciate that the present disclosure also contemplates various other configurations, including those having one or more cathodes and one or more anodes, and various current collectors having electrically active layers disposed on or adjacent to one or more surfaces thereof.

[0102] A typical lithium-ion battery 20 includes a first electrode (e.g., negative electrode 22 or anode) opposite a second electrode (e.g., positive electrode 24 or cathode) and a separator 26 and / or electrolyte 30 disposed therebetween. Although not shown, it is common in lithium-ion battery packs for the cells or batteries to be electrically connected in a stacked or wound configuration to increase the total output. A lithium-ion battery operates by reversibly transporting lithium ions between the first and second electrodes. For example, during charging of the battery, lithium ions can move from the positive electrode 24 to the negative electrode 22, and in the opposite direction when the battery is discharging. The electrolyte 30 is adapted to conduct the lithium ions and can be in liquid, gel, or solid form.

[0103] When a liquid or semi-liquid / gel electrolyte is used, a separator 26 (e.g., a microporous polymeric separator) is thus disposed between the two electrodes 22, 24 and can contain the electrolyte 30, which can also be present in the pores of the negative electrode 22 and the positive electrode 24. When a solid electrolyte is used, the microporous polymeric separator 26 can be omitted. The solid-state electrolyte can also be mixed into the negative electrode 22 and the positive electrode 24. A negative electrode current collector 32 can be located at or near the negative electrode 22, and a positive electrode current collector 34 can be located at or near the positive electrode 24. An external circuit 40 and a load device 42 can be connected to the negative electrode 22 (through its current collector 32) and the positive electrode 24 (through its current collector 34).

[0104] The battery 20 can generate an electrical current during discharge by way of reversible electrochemical reactions that occur when the external circuit 40 is closed (to connect the negative electrode 22 and the positive electrode 24) and the potential of the negative electrode 22 is lower than the positive electrode. The chemical potential difference between the positive electrode 24 and the negative electrode 22 drives electrons produced by a reaction at the negative electrode 22 (e.g., oxidation of lithium intercalation) through the external circuit 40 to the positive electrode 24. Lithium ions also produced at the negative electrode 22 simultaneously transfer to the positive electrode 24 via the electrolyte 30 contained in the separator 26. The electrons migrate through the external circuit 40 and the lithium ions migrate through the separator 26 containing the electrolyte solution 30 in order to form lithium intercalation at the positive electrode 24. As noted above, the electrolyte 30 is also typically present in the negative electrode 22 and the positive electrode 24. The electrical current through the external circuit 40 can be harnessed and directed through a load device 42 until the lithium in the negative electrode 22 is depleted and the capacity of the battery 20 is reduced.

[0105] The battery 20 can be charged or re-energized 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 power source to the battery 20 facilitates a reaction at the positive electrode 24 (e.g., non-spontaneous oxidation of transition metal ions), which in turn produces electrons and lithium ions. The lithium ions flow from the negative electrode 22 through the electrolyte 30 across the separator 26 in order to replenish the positive electrode 24 with lithium for use during the next battery discharge event. In this way, a complete discharge event followed by a complete charge event is considered a cycle, in which lithium ions are cycled between the positive electrode 24 and the negative electrode 22. The external power source that can be used to charge the battery 20 can vary depending on the size, construction, and specific end use of the battery 20. Some notable and exemplary external power sources include, but are not limited to, an AC-DC converter connected to an AC power grid through a wall outlet and a motor vehicle alternator.

[0106] In many lithium-ion battery configurations, each of the negative electrode current collector 32, the negative electrode 22, the separator 26, the positive electrode 24, and the positive electrode current collector 34 are fabricated as relatively thin layers (e.g., thicknesses of a few microns to a few tenths of a millimeter or less) and the layers are assembled in an electrical parallel arrangement to provide a suitable electrical energy and power package. The negative electrode current collector 32 and the positive electrode current collector 34 collect and move free electrons to and from the external circuit 40, respectively.

[0107] Further, as noted above, when using a liquid or semi-liquid electrolyte, the separator 26 acts as an electrical insulator by being sandwiched between the negative electrode 22 and the positive electrode 24 to prevent physical contact and thereby prevent shorting. 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 the lithium ion cycling process to facilitate the functioning of the battery 20. A solid-state electrolyte layer can perform similar ion-conducting and electrical insulating functions without the need for the separator 26 component.

[0108] The battery 20 can include a variety of other components, which, although not depicted herein, are known to those skilled in the art. For example, the battery 20 can include a housing, gaskets, terminal covers, tabs, battery terminals, and any other conventional components or materials that can be located within the 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 in FIG. 1 includes a liquid electrolyte 30 and shows a corresponding battery operating concept. However, as known to those skilled in the art, the battery 20 can also be a solid-state battery including a solid-state electrolyte, which can have a different design.

[0109] The electrodes can generally be incorporated into a variety of commercial battery designs, such as prismatic cells, wound cylindrical cells, button cells, pouch cells, or other suitable cell shapes. The battery can include a single electrode structure of each polarity, or have a stacked structure with 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, with separators disposed therebetween. While positive electrode active materials can be used in batteries for primary or single-charge applications, the resulting battery generally has desirable cycling properties for secondary battery applications during multiple cycles of the battery.

[0110] As noted above, the size and shape of the battery pack 20 can vary depending on the particular application for which it is designed. Vehicles and hand-held consumer electronics are two examples in which battery packs 20 will most likely be designed to different sizes, capacities, and power output specifications. The battery pack 20 can also be connected in series or parallel with other similar lithium-ion cells or battery packs to produce greater voltage output, energy, and power if needed by the load device 42. Thus, the battery pack 20 can generate current toward the load device 42, which is part of the external circuit 40. The load device 42 can be powered by the current through the external circuit 40 as the battery pack 20 discharges. While the electrical load device 42 can be any number of known electrically powered devices, some specific examples include electric motors for electrically powered vehicles, laptop computers, tablet computers, cellular telephones, and cordless power tools or appliances. The load device 42 can also be a power generation device that charges the battery pack 20 for storage of electrical energy.

[0111] The present technology relates to the manufacture of improved electrochemical cells, particularly lithium-ion battery packs. In various instances, such cells are used in vehicle or automotive transportation applications (e.g., motorcycles, boats, tractors, buses, motorcycles, mobile homes, campers, and tanks). However, the present technology can also be used in a wide variety of other industries and applications, including, for example, aerospace components, consumer goods, devices, buildings (e.g., houses, offices, sheds, and warehouses), office equipment and furniture, and industrial equipment machinery, agricultural or farm equipment, or heavy machinery.

[0112] Electrolyte

[0113] Referring back to Figure 1 The positive electrode 24, the negative electrode 22, and the separator 26 can each contain an electrolyte solution or system 30 within the pores thereof, 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, whether in solid, liquid, or gel form, can be used in the lithium-ion battery pack 20. In certain aspects, the electrolyte 30 can be a non-aqueous liquid electrolyte solution that includes a lithium salt dissolved in an organic solvent or mixture of organic solvents. Many non-aqueous liquid electrolyte 30 solutions can be employed in the lithium-ion battery pack 20. In certain instances, the electrolyte 30 can include an aqueous solvent (i.e., a water-based solvent) or a mixed solvent (e.g., an organic solvent containing at least 1 wt% water).

[0114] Suitable lithium salts generally have an inert anion. Examples of lithium salts that are soluble 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 difluoro oxalato borate (LiBF2(C2O4)) (LiODFB); lithium tetraphenylborate (LiB(C6H5)4); lithium bis(oxalato)borate (LiB(C2O4)2) (LiBOB); lithium tetrafluoro oxalato phosphate (LiPF4(C2O4)) (LiFOP); lithium nitrate (LiNO3); lithium hexafluoroarsenate (LiAsF6); lithium trifluoromethanesulfonate (LiCF3SO3); lithium bis(trifluoromethylsulfonyl)imide (LiN(CF3SO2)2) (LiTFSI); lithium bis(fluorosulfonyl)imide (LiN(FSO2)2) (LiFSI); and combinations thereof. In certain variations, electrolyte 30 can include a lithium salt at a 1 M concentration.

[0115] These lithium salts can be soluble in a variety of organic solvents, such as organic ethers or organic carbonates. Organic ethers can include dimethyl ether, glyme (ethylene glycol dimethyl ether or dimethoxyethane (DME, such as 1,2-dimethoxyethane)), diglyme (diethylene glycol dimethyl ether or bis(2-methoxyethyl) ether), triglyme (tri(ethylene glycol) dimethyl ether), additional 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), diglyme (diethylene glycol dimethyl ether), triglyme (tri(ethylene glycol) dimethyl ether), 1,3-dimethoxypropane (DMP), and combinations thereof. Carbonate-based solvents can include various alkyl carbonates, such as cyclic carbonates (e.g., ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate) and acyclic carbonates (e.g., dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl 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).

[0116] In various embodiments, suitable solvents in addition to those described above can be selected from the group consisting of propylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, gamma-butyrolactone, dimethyl sulfoxide, acetonitrile, nitromethane, and mixtures thereof.

[0117] When the electrolyte is a solid electrolyte, it may include compounds selected from the following: LiTi2(PO4)3, LiGe2(PO4)3, Li7La3Zr2O 12 Li3xLa 2 / 3 -xTiO3, Li3PO4, Li3N, Li4GeS4, Li 10 GeP2S 12 , Li2S-P2S5, Li6PS5Cl, Li6PS5Br, Li6PS5I, Li3OCl, Li 2.99 Ba 0.005 ClO, or any combination thereof.

[0118] Porous separator

[0119] In some variations, the porous separator 26 may comprise a microporous polymer separator comprising a polyolefin, including those made of homopolymers (derived from a single monomer component) or hybrids (derived from more than one monomer component), which may be 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 (a single-layer polypropylene separator) and CELGARD® 2340 (a three-layer polypropylene / polyethylene / polypropylene separator) from Celgard LLC.

[0120] When the porous separator 26 is a microporous polymeric separator, it can be a single layer or a multi-layered laminate. For example, in one embodiment, a single polyolefin layer can form the entire microporous polymeric separator 26. In other aspects, the separator 26 can be a fibrous membrane having a large number of pores extending between opposing surfaces and can have, for example, a thickness of less than 1 millimeter. However, as another example, multiple discrete layers of similar or dissimilar polyolefins can be assembled to form the microporous polymeric separator 26. The microporous polymeric separator 26 can also include alternative or in addition to polyolefins, other polymers such as, but not limited to, polyethylene terephthalate (PET), polyvinylidene fluoride (PVDF), polyamide (nylon), polyurethane, polycarbonate, polyester, polyether ether ketone (PEEK), polyether sulfone (PES), polyimide (PI), polyamide-imide, polyether, polyformaldehyde (e.g., acetal), polybutylene terephthalate, polyethylene naphthenate, polybutene, polymethylpentene, polyolefin copolymers, acrylonitrile-butadiene-styrene copolymer (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., VECTRAN™ (Hoechst AG, Germany) and ZENITE® (DuPont, Wilmington, DE)), polyaramid, polyphenylene ether, cellulosic materials, mesoporous silica, or combinations thereof.

[0121] Further, the porous separator 26 can be mixed with a ceramic material, or its surface can be coated with a ceramic material. For example, the ceramic coating can include aluminum oxide (AI2O3), silicon dioxide (SiO2), or combinations thereof. Various commercially available polymers and commercial products for forming the separator 26 are contemplated, as well as a number of manufacturing methods that can be used to manufacture such microporous polymeric separators 26.

[0122] Solid state electrolyte

[0123] In various aspects, the porous separator 26 and the electrolyte 30 can be replaced with a solid-state electrolyte (SSE) that functions as both an electrolyte and a separator. The SSE can be disposed between the positive and negative electrodes. The SSE facilitates the transport of lithium ions while mechanically separating the negative electrode from the positive electrode 22, 24 and providing electrical insulation therebetween. As an example, the SSE can include LiTi2(PO4)3, LiGe2(PO4)3, Li7La3Zr2O 12Li3xLa 2 / 3 -xTiO3, Li3PO4, Li3N, Li4GeS4, Li 10 GeP2S 12 , Li2S-P2S5, Li6PS5Cl, Li6PS5Br, Li6PS5I, Li3OCl, Li 2.99 Ba 0.005 ClO, polyethylene oxide (PEO)-based polymers, polycarbonates, polyesters, polynitriles (e.g., polyacrylonitrile (PAN)), polyalcohols (e.g., polyvinyl alcohol (PVA)), polyamines (e.g., polyethyleneimine (PEI)), polysiloxanes (e.g., polydimethylsiloxane (PDMS)), and fluoropolymers (e.g., polyvinylidene fluoride (PVDF), polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP)), biopolymers such as lignin, chitosan, and cellulose, and any combination thereof.

[0124] Current collector

[0125] The negative and positive electrodes 22, 24 are typically associated with respective negative and positive electrode current collectors 32, 34 to facilitate electron flow between the electrodes and the external circuit 40. The current collectors 32, 34 are electrically conductive and can include a metal, such as a metal foil, a metal grid or mesh, or a porous metal. The porous metal current collector refers to a metal grid having a greater thickness such that a greater amount of the electroactive material is disposed in the metal grid. As examples, the electrically conductive material includes copper, nickel, aluminum, stainless steel, titanium, alloys thereof, or combinations thereof.

[0126] The positive electrode current collector 34 can be formed of aluminum or any other suitable electrically conductive material known to those skilled in the art. The negative electrode current collector 32 can be formed of copper or any other suitable electrically conductive material known to those skilled in the art. The negative electrode current collector typically does not include aluminum because aluminum reacts with lithium, thereby causing large volume expansion and contraction. The severe volume changes can cause the current collector to crack and / or crumble.

[0127] Positive & negative electrodes

[0128] The positive electrode 24 can be formed from or include lithium-based active materials that can undergo lithium intercalation and deintercalation, alloying and dealloying, or plating and stripping while serving as the positive electrode terminal of the lithium-ion battery 20. The positive electrode 24 can include a positive electrode electroactive material. The positive electrode electroactive material can include 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 certain variations, the positive electrode 24 is substantially free of selected metal cations such as nickel (Ni) and cobalt (Co). The positive electrode material (also referred to as a "positive electrode electroactive material") is described in greater detail below in connection with the discussion of Figure 4

[0129] The negative electrode 22 can include a negative electrode electroactive material as a lithium host material that can serve as the negative electrode terminal of the lithium-ion battery 20. Common negative electrode electroactive materials include lithium intercalation materials or alloy host materials. The negative electrode material (also referred to as a "negative electrode electroactive material") is described in greater detail below in connection with the discussion of Figure 4

[0130] In certain aspects, the negative electrode 22 includes metallic lithium, and the negative electrode 22 is a lithium metal electrode (LME). The lithium-ion battery 20 can be a lithium-metal battery or cell. Metallic lithium for the negative electrode of a rechargeable battery has various potential advantages, including having the highest theoretical capacity and the lowest electrochemical potential. As such, a battery incorporating a lithium-metal anode can have a higher energy density, which can potentially double the storage capacity, whereby the size of the battery can be halved, but still last the same amount of time as other lithium-ion batteries.

[0131] Thick electrode

[0132] As used herein, a "thick electrode" is an electrode (i.e., a single-sided electrode or one side of a double-sided electrode) having a thickness greater than or equal to about 100 μm and an area-specific capacity greater than or equal to about 5 mAh / cm 2 As described above, the use of thick electrodes in electrochemical cells can desirably increase the overall cell energy density. However, the performance of thick electrodes can be hindered when the electrodes include certain binders. For example, some binders coat all or a portion of the surface of the electroactive material particles, thereby inhibiting the lithium ion pathway between the electroactive material and the electrolyte. This can result in limited C-rate performance. In addition, certain binders can undergo a change in physicochemical properties during solvent evaporation, resulting in a decrease in the adhesion of particles / particles and particles / current collector in the electrode. This can result in delamination.

[0133] ​​In various aspects, the present disclosure provides electrodes comprising a polymeric binder network. The polymeric binder network comprises a plurality of fibers. The fibers can generally comprise repeating units or segments having a hollow, substantially cylindrical shape. In certain aspects, the fibers can be referred to as "bamboo-type" fibers. For each unit, the wall of the substantially cylindrical shape can comprise a plurality of beads or dots, and a plurality of filaments extending from at least a portion of the beads. The polymeric binder network is elastic and robust. The fibers of the binder make point or line contact with the surface of the electroactive material (as opposed to a surface coating), while allowing lithium ions to flow between the surface of the electroactive material and the electrolyte. The use of a polymeric binder network comprising bamboo-type fibers can provide thick electrodes with improved lifetime and performance compared to electrodes comprising traditional binders, and allow the electrodes to be cycled at high C-rates in electrochemical cells.

[0134] Reference is made to Figure 2 An electrode assembly 200 according to various aspects of the present disclosure is provided. The electrode assembly 200 comprises a current collector 202, two electroactive layers 204 (also referred to as "electrodes"), and two electrically conductive binder layers 206 disposed between the current collector 202 and each electroactive layer 204, respectively. Although the electrode assembly 200 is double-sided, the present disclosure also provides single-sided electrode assemblies (e.g., a single electroactive layer coupled to a side of the current collector by a single layer of electrically conductive binder) and electrodes that are not coupled to a current collector (e.g., a single electroactive layer).

[0135] Each electroactive layer 204 can be a thick electrode. In certain aspects, each electroactive layer 204 can define a first thickness 210 that is greater than or equal to about 100 μιη, optionally greater than or equal to about 150 μιη, optionally greater than or equal to about 200 μιη, optionally greater than or equal to about 300 μιη, optionally greater than or equal to about 400 μιη, optionally greater than or equal to about 500 μιη, optionally greater than or equal to about 750 μιη, optionally greater than or equal to about 1 mm, optionally greater than or equal to about 1.25 mm, optionally greater than or equal to about 1.5 mm, or optionally greater than or equal to about 1.75 mm. The first thickness 210 can be less than or equal to about 2 mm, optionally less than or equal to about 1.75 mm, optionally less than or equal to about 1.5 mm, optionally less than or equal to about 1.25 mm, optionally less than or equal to about 1 mm, optionally less than or equal to about 750 μιη, optionally less than or equal to about 500 μιη, optionally less than or equal to about 400 μιη, optionally less than or equal to about 300 μιη, optionally less than or equal to about 200 μιη. In certain aspects, the first thickness 210 can be, by way of example, greater than or equal to about 100 μιη to less than or equal to about 2 mm, or optionally greater than or equal to about 150 μιη to less than or equal to about 500 μιη. In certain aspects, the first thickness 210 through the electroactive layer 204 can vary by about 5%.

[0136] The electroactive layer 204 can define a porosity that is greater than or equal to about 25 vol%, optionally greater than or equal to about 30 vol%, optionally greater than or equal to about 35 vol%, optionally greater than or equal to about 40 vol%, optionally greater than or equal to about 45 vol%, optionally greater than or equal to about 50 vol%, optionally greater than or equal to about 55 vol%. The porosity can be less than or equal to about 60 vol%, optionally less than or equal to about 55 vol%, optionally less than or equal to about 50 vol%, optionally less than or equal to about 45 vol%, optionally less than or equal to about 40 vol%, optionally less than or equal to about 35 vol%, or optionally less than or equal to about 30 vol%. In certain aspects, the porosity can be, by way of example, greater than or equal to about 25 vol% to less than or equal to about 45 vol%.

[0137] The current collector 202 can include an electrically conductive material. By way of example, the current collector 202 can be in the form of a foil or film as shown, or in the form of a web (see, e.g., Figure 3 ). By way of example, the electrically conductive material can include a metal, a carbon-based material, an organic-based material, or a combination thereof. In certain aspects, the current collector 202 can include an electrically conductive material, as described above in Figure 1The current collector 202 can define a second thickness 220. The second thickness 220 can be greater than or equal to about 4 μιη, optionally greater than or equal to about 6 μιη, optionally greater than or equal to about 10 μιη, optionally greater than or equal to about 15 μιη, optionally greater than or equal to about 20 μιη, or optionally greater than or equal to about 25 μιη. The second thickness 220 can be less than or equal to about 30 μιη, optionally less than or equal to about 25 μιη, optionally less than or equal to about 20 μιη, optionally less than or equal to about 15 μιη, optionally less than or equal to about 10 μιη, optionally less than or equal to about 8 μιη, or optionally less than or equal to about 6 μιη. In one example, the second thickness 220 can be greater than or equal to about 4 μιη to less than or equal to about 30 μιη, optionally greater than or equal to about 6 μιη to less than or equal to about 15 μιη, or about 23 μιη.

[0138] The electrically conductive adhesive layer 206 can include an electrically conductive filler and a polymer. The mass ratio of the electrically conductive filler to the polymer can be greater than or equal to about 0.001, optionally greater than or equal to about 0.01, optionally greater than or equal to about 0.05, optionally greater than or equal to about 0.1, optionally greater than or equal to about 0.2, optionally greater than or equal to about 0.3, or optionally greater than or equal to about 0.4. The mass ratio can be less than or equal to about 0.5, optionally less than or equal to about 0.4, optionally less than or equal to about 0.3, optionally less than or equal to about 0.2, optionally less than or equal to about 0.1, optionally less than or equal to about 0.05, or optionally less than or equal to about 0.01. In certain aspects, the mass ratio can be greater than or equal to about 0.001 to less than or equal to about 0.5.

[0139] The electrically conductive filler includes an electrically conductive material. The electrically conductive material can include a carbon-based material, a metal, or a combination thereof. In certain aspects, as an example, the carbon-based material can include carbon black (e.g., SUPER P manufactured by TIMCAL Belgium), graphene, carbon nanotubes (CNTs), carbon nanofibers, or a combination thereof. In certain aspects, as an example, the metal material can include silver, nickel, aluminum, an alloy thereof, or a combination thereof. The polymer can be solvent resistant and have good adhesive properties. In certain aspects, as an example, the polymer can include an epoxy, a polyimide (PI), a polyester, a vinyl ester, a polyacrylic acid (PAA), one or more thermoplastic polymers (e.g., polyvinylidene fluoride (PVDF), polyamide, silicone, acrylic), or a combination thereof.

[0140] The conductive binder layer 206 defines a third thickness 230. In certain aspects, the third thickness 230 is greater than or equal to about 0.5 pm, optionally greater than or equal to about 1 pm, optionally greater than or equal to about 5 pm, optionally greater than or equal to about 10 pm, or optionally greater than or equal to about 15 pm. The third thickness 230 can be less than or equal to about 20 pm, optionally less than or equal to about 15 pm, optionally less than or equal to about 10 pm, optionally less than or equal to about 5 pm, or optionally less than or equal to about 1 pm. In certain aspects, by way of example, the third thickness 230 is greater than or equal to about 0.5 pm to less than or equal to about 20 pm. In one example, the conductive binder layer 206 includes a conductive filler including SUPER P carbon black and a polymer including PAA at a mass ratio of about 1 / 3. In another example, the conductive binder layer 206 includes a conductive filler including single-walled carbon nanotubes, SWCNTs, and a polymer including PVDF at a mass ratio of about 0.002.

[0141] Each electroactive layer 204 can have an area-specific capacity greater than or equal to about 4 mAh / cm 2 , optionally greater than or equal to about 5 mAh / cm 2 , optionally greater than or equal to about 10 mAh / cm 2 , optionally greater than or equal to about 15 mAh / cm 2 , optionally greater than or equal to about 20 mAh / cm 2 , optionally greater than or equal to about 25 mAh / cm 2 , optionally greater than or equal to about 30 mAh / cm 2 , optionally greater than or equal to about 35 mAh / cm 2 , optionally greater than or equal to about 40 mAh / cm 2 , or optionally greater than or equal to about 45 mAh / cm 2 . The area-specific capacity can be less than or equal to about 50 mAh / cm 2 , optionally less than or equal to about 45 mAh / cm 2 , optionally less than or equal to about 40 mAh / cm 2 , optionally less than or equal to about 35 mAh / cm 2 , optionally less than or equal to about 30 mAh / cm 2 , optionally less than or equal to about 25 mAh / cm 2 , optionally less than or equal to about 20 mAh / cm 2 , optionally less than or equal to about 15 mAh / cm 2 , or optionally less than or equal to about 10 mAh / cm 2In certain aspects, the area specific capacity can be greater than or equal to about 5 mAh / cm 2 to less than or equal to about 50 mAh / cm 2 , optionally about 5 mAh / cm 2 to less than or equal to about 10 mAh / cm 2 The area specific capacity on the electroactive layer 200 can vary by about 5%.

[0142] The compaction density (or electrode density) is defined as the volumetric mass density of the electrode material (e.g., the mixture of electroactive material, binder, and conductive additive) in the electrode. In certain aspects, the compaction density of each electroactive layer 204 can generally be greater than or equal to about 1 g / cm 3 to less than or equal to about 4 g / cm 3 The compaction density can vary by about 3%. In certain aspects, the electroactive layer 204 is a positive electroactive layer and the compaction density is greater than or equal to about 2 g / cm 3 to less than or equal to about 4 g / cm 3 , or optionally greater than or equal to about 3.3 g / cm 3 to less than or equal to about 3.7 g / cm 3 In certain aspects, the electroactive layer 204 is a negative electroactive layer and the compaction density is greater than or equal to about 1 g / cm 3 to less than or equal to about 3 g / cm 3 , or optionally greater than or equal to about 1.4 g / cm 3 to less than or equal to about 2 g / cm 3 .

[0143] Referring to Figure 3 , another electrode assembly 300 is provided in accordance with aspects of the present disclosure. The electrode assembly 300 includes a current collector 302 and two electroactive layers 304 on opposite sides of the current collector 302. The electroactive layers 304 can be the same as the electroactive layers 204 of Figure 2 In certain aspects, the electrode assembly 300 can be free of conductive binder such that the electroactive layers 304 directly contact the current collector 302. The current collector 302 can be the same as the current collector 202 of Figure 2 except as described below.

[0144] The current collector 302 may be porous or mesh. The current collector 302 may be defined as having a porosity of greater than or equal to about 0.01 vol%, optionally greater than or equal to about 0.1 vol%, optionally greater than or equal to about 1 vol%, optionally greater than or equal to about 5 vol%, optionally greater than or equal to about 10 vol%, optionally greater than or equal to about 15 vol%, optionally greater than or equal to about 20 vol%, optionally greater than or equal to about 25 vol%, optionally greater than or equal to about 30 vol%, optionally greater than or equal to about 35 vol%, optionally greater than or equal to about 40 vol%, or optionally greater than or equal to about 45 vol%. The porosity can be less than or equal to about 50% by volume, optionally less than or equal to about 45% by volume, optionally less than or equal to about 40% by volume, optionally less than or equal to about 35% by volume, optionally less than or equal to about 30% by volume, optionally less than or equal to about 25% by volume, optionally less than or equal to about 20% by volume, optionally less than or equal to about 15% by volume, optionally less than or equal to about 10% by volume, optionally less than or equal to about 5% by volume, optionally less than or equal to about 1% by volume, or optionally less than or equal to about 0.1% by volume. In some aspects, as an example, the porosity is greater than or equal to about 0.01% by volume to less than or equal to about 50% by volume.

[0145] The current collector 302 may be defined as having an average pore size greater than or equal to about 5 μm, optionally greater than or equal to about 10 μm, optionally greater than or equal to about 25 μm, optionally greater than or equal to about 50 μm, optionally greater than or equal to about 100 μm, optionally greater than or equal to about 150 μm, optionally greater than or equal to about 200 μm, optionally greater than or equal to about 250 μm, optionally greater than or equal to about 300 μm, optionally greater than or equal to about 350 μm, optionally greater than or equal to about 400 μm, or optionally greater than or equal to about 450 μm. The pore size may be less than or equal to about 500 μm, optionally less than or equal to about 450 μm, optionally less than or equal to about 400 μm, optionally less than or equal to about 350 μm, optionally less than or equal to about 300 μm, optionally less than or equal to about 250 μm, optionally less than or equal to about 200 μm, optionally less than or equal to about 150 μm, optionally less than or equal to about 100 μm, optionally less than or equal to about 50 μm, optionally less than or equal to about 25 μm, or optionally less than or equal to about 10 μm. In some aspects, as an example, the pore size is greater than or equal to about 5 μm to less than or equal to about 500 μm.

[0146] Reference Figure 4 An electroactive layer 400 is provided as a portion of various aspects of this disclosure. The electroactive layer 400 is compatible with... Figure 2 Electroactive layer 204 and / orFigure 3 The electroactive layer 304 of FIG. 3A is the same as or similar to the electroactive layer 304 of FIG. 3B. The electroactive layer 400 includes a plurality of electroactive material particles 402, a plurality of electrically conductive particles 404, and a polymeric binder network 406. In certain other aspects, the electroactive layer 400 can include the electroactive material particles 402 and the polymeric binder network 406, but substantially no electrically conductive material.

[0147] Electroactive material

[0148] The electroactive layer 400 can include the electroactive material particles 402 in an amount greater than or equal to about 80 wt%, optionally greater than or equal to about 85 wt%, optionally greater than or equal to about 90 wt%, or optionally greater than or equal to about 96 wt%. The electroactive layer 400 can include the electroactive material particles 402 in an amount less than or equal to about 98 wt%, optionally less than or equal to about 96 wt%, optionally less than or equal to about 90 wt%, or optionally less than or equal to about 85 wt%. In certain aspects, the electroactive layer 400 can include the electroactive material particles 402 in an amount greater than or equal to about 80 wt% to less than or equal to about 98 wt%, by way of example.

[0149] The electroactive material particles 402 can include a positive electroactive material (also referred to as a "cathode material") or a negative electroactive material (also referred to as an "anode material").

[0150] In certain aspects, the positive electroactive material is selected from olivine compounds, rock salts, cobalt-free layered oxides, rock salt layered oxides, spinels, olivine, borates, silicates, organic compounds, other types of positive electrode materials, or any combination thereof. For example, the olivine compounds can include LiV2(PO4)3, LiFePO4(LFP), LiCoPO4, and / or lithium manganese iron phosphate (LMFP). For example, the LMFP can include LiMnFePO4and / or LiMn x Fe 1-x PO4, where 0 < x < 1. For example, the LiMn x Fe 1-x PO4, where 0 < x < 1. Examples of LiMn 0.7 Fe 0.3 PO4, LiMn 0.6 Fe 0.4 PO4, LiMn 0.8 Fe 0.2 PO4, and LiMn 0.75 Fe 0.25 PO4. For example, the rock salts, cobalt-free layered oxides can include LiNi x Mn 1-x O2, for example LiNi 0.75 Mn0.25 O2NM75) and / or LiNi x Mn y Al 1-x-y O2(e.g., LiNi 0.94 Mn 0.04 Al 0.02 O2NMA). For example, the rock salt layered oxides can include LiNi x Mn y Co 1-x-y O2, LiNi x Mn 1-x O2, Li 1+x MO2(e.g., LiCoO2, LiNiO2, LiMnO2, and / or LiNi 0.5 Mn 0.5 O2), lithium nickel manganese cobalt oxide (NMC) (e.g., NMC 111, NMC 523, NMC 622, NMC 721, and / or NMC 811), lithium nickel manganese cobalt aluminum oxide (NMCA), and / or lithium nickel cobalt aluminum oxide (NCA). For example, the spinels can include LiMn2O4and / or LiNi 0.5 Mn 1.5 O4. For example, the olivine compounds can include LiVPO4F. For example, the borate compounds can include LiFeBO3, LiCoBO3, and / or LiMnBO3. For example, the silicate compounds can include Li2FeSiO4, Li2MnSiO4, and / or LiMnSiO4F. For example, the organic compounds can include (2,5-dilithiooxy)terephthalic acid dilithium (as described in Stéven Renault, Sébastien Gottis, Anne-Lise Barrés, Matthieu Courty, Oliver Chauvet, Franck Dolhem, and Philippe Poizot, A Green Li-Organic Battery Working as a Fuel Cell in Case of Emergency , ELEC. SUPPLEMENTARY INFO. FORENERGY & ENVTL. SCI. (2013), which is incorporated by reference herein in its entirety) and / or polyimide. An example of another type of positive electrode electroactive material is a sulfur-containing material, such as sulfur.

[0151] Some positive electrode electroactive materials, such as olivine compounds, rock salt, cobalt-free layered oxides, rock salt layered oxides, and / or spinels, can be coated and / or doped. Doping agents can include magnesium (Mg), aluminum (Al), yttrium (Y), scandium (Sc), and the like. In certain aspects, positive electrode electroactive materials including LMFP compounds can be doped with about 10 wt% of one or more doping agents.

[0152] In certain aspects, the negative electrode electroactive material is selected from carbonaceous materials (e.g., CNTs, graphite, and / or graphene), lithium-containing materials (e.g., lithium and / or lithium alloys), tin-containing materials (e.g., tin and / or tin alloys), lithium titanium oxides (e.g., Li4Ti50i2O 12 ), metal oxides (e.g., V2O5, SnO2, and / or Co3O4), metal sulfides (e.g., FeS), silicon-containing materials (e.g., silicon, silicon oxide, silicon alloys, silicon-graphite, silicon oxide graphite, and / or silicon alloy graphite, any of which can optionally be lithiated), or any combination thereof.

[0153] Conductive material

[0154] The electroactive layer 400 can include the conductive material 404 in an amount greater than or equal to about 0.5 wt%, optionally greater than or equal to about 1 wt%, optionally greater than or equal to about 5 wt%, or optionally greater than or equal to about 10 wt%. The electroactive layer 400 can include the conductive material 404 in an amount less than or equal to about 15 wt%, optionally less than or equal to about 10 wt%, optionally less than or equal to about 5 wt%, or optionally less than or equal to about 1 wt%. In certain aspects, as an example, the electroactive layer 400 can include the conductive material 404 in an amount greater than or equal to about 0.5 wt% to less than or equal to about 15 wt%.

[0155] The conductive material 404 can include any conductive material described in the discussion of Figure 1 , supra. Additionally or alternatively, in certain aspects, the conductive material 404 can include a carbon-based material, a metal (e.g., a metal wire), a metal oxide, or any combination thereof. As an example, the carbon-based material can include carbon black (e.g., SUPER P carbon black manufactured by TIMCAL Belgium and / or KETJENBLACK carbon black), graphene, carbon nanotubes (CNTs), carbon nanofibers, or combinations thereof. In certain aspects, as an example, the metal material can include silver, nickel, aluminum, alloys thereof, or combinations thereof. As an example, the metal oxide can include simple oxides such as RuO2, SnO2, ZnO, and / or Ge2O3, superconducting oxides such as YBa2Cu3O7and / or La 0.75 Ca 0.25 MnO3, or combinations thereof.

[0156] Polymer binder network

[0157] The electroactive layer 400 can include the polymeric binder network (i.e., the polymer of the polymeric binder network 406) in an amount greater than or equal to about 0.3 wt%, optionally greater than or equal to about 0.5 wt%, optionally greater than or equal to about 8 wt%, optionally greater than or equal to about 0.75 wt%, optionally greater than or equal to about 1 wt%, optionally greater than or equal to about 2 wt%, optionally greater than or equal to about 5 wt%, or optionally greater than or equal to about 8 wt%. The electroactive layer 400 can include the polymeric binder network in an amount less than or equal to about 10 wt%, optionally less than or equal to about 8 wt%, optionally less than or equal to about 5 wt%, optionally less than or equal to about 2 wt%, optionally less than or equal to about 1 wt%, or optionally less than or equal to about 0.75 wt%. In certain aspects, by way of example, the electroactive layer 400 can include the polymeric binder network 406 in an amount greater than or equal to about 0.3 wt% to less than or equal to about 10 wt%, or optionally greater than or equal to about 0.75 wt% to less than or equal to about 2 wt%.

[0158] The polymeric binder network 406 includes a polymer. The polymer can be elastic and robust. In certain aspects, the polymer includes polytetrafluoroethylene (PTFE), PVDF, perfluoroalkoxy alkanes (PFA), fluorinated ethylene propylene (FEP), ethylene-chlorotrifluoroethylene (ECTFE), ethylene-tetrafluoroethylene (ETFE), or combinations thereof. In certain aspects, the polymeric binder network 406 consists essentially of the polymer.

[0159] The polymeric binder network 406 includes a plurality of fibers 410. At least a portion of the fibers 410 are in direct contact with a surface of the electroactive material particles 402. Referring to Figure 5 , one of the plurality of fibers 410 according to various aspects of the present disclosure is provided. Although Figure 5 the fibers 410 are shown as linear, the fibers 410 need not be linear and can be provided in a variety of shapes to form the polymeric binder network 406, as shown in Figure 4 .

[0160] Each fiber 410 defines a first length 500 that is greater than or equal to about 5 μιη, optionally greater than or equal to about 10 μιη, optionally greater than or equal to about 20 μιη, optionally greater than or equal to about 50 μιη, optionally greater than or equal to about 100 μιη, optionally greater than or equal to about 500 μιη, optionally greater than or equal to about 1 mm, optionally greater than or equal to about 5 mm, optionally greater than or equal to about 10 mm, optionally greater than or equal to about 50 mm, optionally greater than or equal to about 100 mm, optionally greater than or equal to about 500 mm, or optionally greater than or equal to about 1 cm, or optionally greater than or equal to about 1.5 cm. The first length 500 can be less than or equal to about 2 cm, optionally less than or equal to about 1.5 cm, optionally less than or equal to about 1 cm, optionally less than or equal to about 500 mm, optionally less than or equal to about 100 mm, optionally less than or equal to about 50 mm, optionally less than or equal to about 10 mm, optionally less than or equal to about 5 mm, optionally less than or equal to about 1 mm, optionally less than or equal to about 500 μιη, optionally less than or equal to about 100 μιη, optionally less than or equal to about 50 μιη, optionally less than or equal to about 20 μιη, or optionally less than or equal to about 10 μιη. In certain aspects, by way of example, the first length 500 can be greater than or equal to about 5 μιη to less than or equal to about 2 cm, or optionally greater than or equal to about 20 μιη to less than or equal to about 500 μιη.

[0161] Each fiber 410 defines a first diameter 502. The first diameter 502 can be greater than or equal to about 0.1 μιη, optionally greater than or equal to about 0.5 μιη, optionally greater than or equal to about 1 μιη, optionally greater than or equal to about 5 μιη, optionally greater than or equal to about 10 μιη, optionally greater than or equal to about 20 μιη, optionally greater than or equal to about 50 μιη, optionally greater than or equal to about 75 μιη, optionally greater than or equal to about 100 μιη, optionally greater than or equal to about 200 μιη, optionally greater than or equal to about 300 μιη, or optionally greater than or equal to about 400 μιη. The first diameter 502 can be less than or equal to about 500 μιη, optionally less than or equal to about 400 μιη, optionally less than or equal to about 300 μιη, optionally less than or equal to about 200 μιη, optionally less than or equal to about 100 μιη, optionally less than or equal to about 75 μιη, optionally less than or equal to about 50 μιη, optionally less than or equal to about 20 μιη, optionally less than or equal to about 10 μιη, optionally less than or equal to about 5 μιη, optionally less than or equal to about 1 μιη, optionally less than or equal to about 0.5 μιη. In certain aspects, the first diameter 502 can be greater than or equal to about 0.1 μιη to less than or equal to about 500 μιη.

[0162] Each fiber 410 can generally include a wall 504. The wall 504 can be a hollow cylindrical wall. In certain aspects, the wall 504 can have a substantially circular cross-section, a substantially rectangular cross-section (e.g., a substantially square cross-section), or any other closed polygonal cross-section as shown. The wall 504 can at least partially define an interior region 506.

[0163] Each fiber 410 can include a plurality of repeating units or segments 510. Each unit 510 can include a wall 504 and an interior region 506. The units 510 can be arranged end-to-end and physically connected to one another. Thus, considering the hollow cylindrical structure including repeating units, the fiber 410 can be referred to as a bamboo fiber. The units 510 can have similar structures and properties without being identical.

[0164] Each unit 510 defines a second length 512. The second length 512 can be greater than or equal to about 0.1 μιη, optionally greater than or equal to about 0.5 μιη, optionally greater than or equal to about 1 μιη, optionally greater than or equal to about 2 μιη, optionally greater than or equal to about 5 μιη, optionally greater than or equal to about 8 μιη, optionally greater than or equal to about 10 μιη, optionally greater than or equal to about 20 μιη, optionally greater than or equal to about 30 μιη, or optionally greater than or equal to about 40 μιη. The second length 512 can be less than or equal to about 50 μιη, optionally less than or equal to about 40 μιη, optionally less than or equal to about 30 μιη, optionally less than or equal to about 20 μιη, optionally less than or equal to about 10 μιη, optionally less than or equal to about 8 μιη, optionally less than or equal to about 5 μιη, optionally less than or equal to about 2 μιη, optionally less than or equal to about 1 μιη, or optionally less than or equal to about 0.5 μιη. In certain aspects, by way of example, the second length 512 can be greater than or equal to about 0.1 μιη to less than or equal to about 50 μιη.

[0165] Each unit 510 can include a first portion 514 and a second portion 516. Referring to Figure 6 , the first portion 514 includes a plurality of dots or beads 600. The second portion 516 includes a plurality of filaments 602 (which can be microfibers). In certain aspects, the boundary between the first and second portions 514, 516 is not rigid, and as shown, the first portion 514 can also include filaments 612 and / or the second portion 516 can also include beads 600. Further, the longitudinal position (i.e., parallel to the first and second lengths 500, 512, shown in Figure 5 , of the first and second portions 514, 516 can vary about the circumference of the wall 504.

[0166] The filament 602 extends from at least a portion of the bead 600. The bead 600 and the filament 602 together form the wall 504. In some aspects, in electrochemical cells including the electroactive layer 400... Figure 4 During the cycle of fiber 410 ( Figure 4 –5) can be configured to be further fibrillated, such that a portion of the beads 600 are stretched into filaments 602. For example, when the electroactive material particles 402 ( Figure 4 (e.g., silicon) can undergo fibrillation during cycling when volume expansion occurs during lithiation.

[0167] In some respects, bead 600 may be defined as an irregular shape. Bead 600 may have an average second diameter greater than or equal to about 10 nm, optionally greater than or equal to about 20 nm, optionally greater than or equal to about 50 nm, optionally greater than or equal to about 100 nm, optionally greater than or equal to about 250 nm, optionally greater than or equal to about 500 nm, or optionally greater than or equal to about 750 nm. The average second diameter may be less than or equal to about 1 μm, optionally less than or equal to about 750 nm, optionally less than or equal to about 500 nm, optionally less than or equal to about 250 nm, optionally less than or equal to about 100 nm, optionally less than or equal to about 50 nm, or optionally less than or equal to about 20 nm. In some respects, the average second diameter may be greater than or equal to about 10 nm to less than or equal to about 1 μm. In other respects, bead 600 may be defined as a substantially spherical shape and / or an elongated spherical shape.

[0168] The filament 602 may be defined as having an average third diameter greater than or equal to about 1 nm, optionally greater than or equal to about 2 nm, optionally greater than or equal to about 5 nm, optionally greater than or equal to about 10 nm, optionally greater than or equal to about 25 nm, optionally greater than or equal to about 50 nm, optionally greater than or equal to about 100 nm, optionally greater than or equal to about 150 nm, optionally greater than or equal to about 200 nm, or optionally greater than or equal to about 250 nm. The average third diameter may be less than or equal to about 300 nm, optionally less than or equal to about 250 nm, optionally less than or equal to about 200 nm, optionally less than or equal to about 150 nm, optionally less than or equal to about 100 nm, optionally less than or equal to about 50 nm, optionally less than or equal to about 10 nm, optionally less than or equal to about 5 nm, or optionally less than or equal to about 2 nm. In some aspects, the average third diameter may be greater than or equal to about 1 nm to less than or equal to about 300 nm. Example

[0169] Reference Figure 7According to various aspects of the present disclosure, a plurality of polymeric binder fibers 700 are provided. Each polymeric binder fiber 700 includes a wall 702 that at least partially defines an interior region (not shown). The wall 702 includes a plurality of dots or beads 704 and a plurality of filaments or microfibers 706. Each fiber 700 can generally include a plurality of end-to-end repeating units or segments 710.

[0170] Method of making thick electrode

[0171] Referring to Figure 8 According to various aspects of the present disclosure, methods of manufacturing electrodes, such as electroactive layers 200, 300, and / or 400, are provided. The methods generally include preparing a mixture of an electroactive material, a polymeric binder, and optionally a conductive material at 800, depositing the mixture onto a substrate at 804, pre-rolling the mixture on the substrate to form an electrode precursor, final-rolling the electrode precursor to form a continuous electrode film at 812, optionally securing the continuous electrode film to a current collector to form a continuous electrode assembly at 816, and optionally cutting the continuous electrode assembly to form individual electrode assemblies at 820.

[0172] Referring to Figure 9 According to various aspects of the present disclosure, examples of methods of Figure 8 A mixture 900 can be provided to a hopper 902. The mixture 900 can include an electroactive material, a polymeric binder, and optionally a conductive material, such as those described above in the discussion of Figures 4-6 The polymeric binder can be at least partially fibrillated such that it includes a plurality of dots or beads and a plurality of filaments prior to forming an electrode or cycling an electrode in an electrochemical cell. Preparation of the mixture 900 can occur prior to introducing the mixture 900 into the hopper 902. The mixing can occur in any commercially available mixer (not shown). Additionally or alternatively, the mixture can be prepared in the hopper 902.

[0173] The mixture 900 can be discharged from the hopper 902 and deposited onto a surface of a moving substrate 904. The mixture 900 can be conveyed on the moving substrate 904 to a first pair of rollers 906. The first pair of rollers 906 can pre-roll the mixture 900 to form a continuous electrode precursor 910. The continuous electrode precursor 910 can define a first thickness 912.

[0174] The continuous electrode precursor 910 can be conveyed to a second pair of rollers 914. In certain aspects, the electrode continuous precursor 910 can be removed from the substrate 904 between the first pair of rollers 906 and the second pair of rollers 914. The second pair of rollers 914 can final-roll the continuous electrode precursor 910 to form a continuous electrode film 920. The continuous electrode film 920 can define a second thickness 922 that is less than the first thickness 912.

[0175] The continuous electrode film 920 can be wound onto a roll 924. Prior to or after being wound onto the roll 924, the continuous electrode film 920 can be secured to a continuous current collector (e.g., a foil or a mesh) to form a continuous electrode assembly. In one example, securing the continuous electrode film 920 to the continuous current collector can include applying a conductive adhesive between the continuous electrode film 920 and the continuous current collector, as when the continuous current collector is a foil. In another example, securing the continuous electrode film 920 to the continuous current collector can include compacting the continuous electrode film 920 onto the continuous current collector, as when the continuous current collector is a mesh.

[0176] The continuous electrode film 920 (or the continuous electrode assembly) can be optionally cut into individual sheets to form individual electrode films (or individual electrode assemblies). The optional cutting can be performed prior to or after optionally securing the electrode film to a current collector. Although Figure 9 A continuous process is depicted, Figure 8 The method of

[0177] The foregoing description is merely illustrative in nature and is in no way intended to limit the disclosure, its application, or uses. The broad teachings of the disclosure can be implemented in a variety of forms. Therefore, while this disclosure includes particular examples, the true scope of the disclosure should not be so limited since other modifications will become apparent upon a study of the drawings, the specification, and the appended claims. It should be understood that one or more steps within a method can be performed by, for example, different parties in succession or simultaneously. As such, the disclosure should not be construed as limited to the particular embodiments set forth herein. Rather, this disclosure is to cover all modifications, equivalents, and alternatives falling within the scope of the disclosure.

Claims

1. Electrodes used in electrochemical cells, including: Polymer adhesive network, comprising: A plurality of fibers defining the polymer adhesive network, each of the plurality of fibers comprising: A plurality of segments arranged end-to-end and physically connected to each other, and each of the plurality of segments comprising: Multiple beads, and A plurality of filaments extending from at least a portion of the plurality of beads; and Multiple electroactive material particles in the voids of the polymer adhesive network, The plurality of beads are each defined with a diameter greater than or equal to 10 nm and less than or equal to 1 μm; and the plurality of filaments are each defined with a diameter greater than or equal to 1 nm and less than or equal to 300 nm.

2. The electrode according to claim 1, wherein Each of the multiple segments includes The first part includes multiple beads, and The second part includes multiple filaments.

3. The electrode of claim 2, wherein each of the plurality of segments is defined as having a length greater than or equal to 0.1 μm and less than or equal to 50 μm.

4. The electrode according to claim 2, wherein Each of the plurality of segments includes a basic cylindrical wall that defines an internal region.

5. The electrode of claim 4, wherein the wall of the basic cylindrical shape defines a diameter greater than or equal to 0.1 μm and less than or equal to 500 μm.

6. The electrode of claim 1, wherein each of the plurality of fibers is defined as having a length greater than or equal to 5 μm and less than or equal to 2 cm.

7. The electrode of claim 1, wherein the electrode has a thickness greater than or equal to 100 μm and less than or equal to 2 mm.

8. The electrode of claim 1, wherein the polymer binder network is present in an amount greater than or equal to 0.3% by weight and less than or equal to 10% by weight.

9. The electrode according to claim 1, wherein the electrode has a capacitance of 4 mAh / cm³ or greater. 2 And less than or equal to 50 mAh / cm 2 The area is greater than the capacity.

10. The electrode according to claim 1, wherein (i) The plurality of electroactive material particles contain a positive electrode electroactive material, and the electrode has a concentration greater than or equal to 2 g / cm³. 3 And less than or equal to 4 g / cm 3 The compaction density, or (ii) The plurality of electroactive material particles contain a negative electrode electroactive material, and the electrode has a concentration greater than or equal to 1 g / cm³. 3 And less than or equal to 3 g / cm 3 The compaction density.

11. The electrode of claim 1, wherein the electrode has a porosity greater than or equal to 25% by volume and less than or equal to 60% by volume.

12. The electrode of claim 1, wherein at least a portion of the plurality of beads is configured to be fibrillated during cycling of an electrochemical cell containing the electrode.

13. The electrode of claim 1, wherein the polymer binder network comprises polytetrafluoroethylene (PTFE).

14. The electrode according to claim 1, further comprising: Conductive materials.

15. The electrode according to claim 1, wherein the plurality of electroactive material particles comprise one of the following: (i) The positive electrode active material is selected from: rock salt layered oxides, borates, silicates, sulfur, or any combination thereof, or (ii) The negative electrode active material is selected from: carbonaceous materials, lithium-containing materials, tin-containing materials, silicon-containing materials, or any combination thereof.

16. The electrode according to claim 1, wherein the plurality of electroactive material particles comprise one of the following: (i) The positive electrode active material is selected from: olivine compounds, rock salt, cobalt-free layered oxides, spinel, lithium hydroxyphosphorus iron oxide, or any combination thereof, or (ii) The negative electrode active material is selected from: metal oxides, metal sulfides, lithium-containing silicon materials, or any combination thereof.

17. Electrode assembly, including: Current collector, which contains conductive material; and An electrode layer on the current collector, the electrode layer comprising: Polymer adhesive network, comprising: A plurality of fibers defining the polymer adhesive network, each of the plurality of fibers comprising: A plurality of segments arranged end-to-end and physically connected to each other, and each of the plurality of segments comprising: Multiple beads, and A plurality of filaments extending from at least a portion of the plurality of beads; and Multiple electroactive material particles in the voids of the adhesive polymer network, The plurality of beads are each defined with a diameter greater than or equal to 10 nm and less than or equal to 1 μm; and the plurality of filaments are each defined with a diameter greater than or equal to 1 nm and less than or equal to 300 nm.

18. The electrode assembly of claim 17, wherein the current collector comprises a mesh, and the electrode layer is in direct contact with the mesh.

19. The electrode assembly of claim 17, further comprising: Conductive adhesive between the current collector and the electrode layer.

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