Cathode and method of forming same

Abstract

Electrochemical cells and methods of forming the same are described. An electrochemical cell includes an anode, a cathode, a separator, and a liquid electrolyte. The cathode includes an active material, a conductive material, a binder, and a gelling electrolyte. The separator is disposed between the anode and the cathode. The separator is configured to prevent direct contact between the anode and the cathode. The liquid electrolyte transports ions between the cathode and the anode.

Description

Technical Field

[0001] This application claims the benefit of U.S. Patent Application No. 17 / 970,014, filed Oct. 20, 2022, the entire content of which is incorporated herein by reference.

[0002] The present disclosure particularly relates to batteries or electrochemical cells. Background Art

[0003] A lithium battery may include one or more electrochemical cells. A lithium battery may include a primary battery or a rechargeable battery. Each electrochemical cell unit includes an anode (e.g., a negative electrode), a cathode (e.g., a positive electrode), and an electrolyte disposed within a housing or cell case. A separator made of a porous polymer or other suitable material may also be disposed between or among the anode and the cathode to prevent direct contact between the anode and the cathode. The anode includes a current collector having an active material, and the cathode includes a current collector having an active material.

[0004] Lithium batteries or electrochemical cells typically use a liquid electrolyte to provide high conductivity and wettability thereof on the electrode surfaces. Compared with other electrolyte compositions or higher viscosity liquid electrolytes, a low viscosity liquid electrolyte has a relatively high ionic conductivity that can provide a higher power output. Additionally, a low viscosity liquid electrolyte can be more easily dispensed into the battery during battery assembly. However, the interaction between a low viscosity liquid electrolyte and a typical lithium battery cathode can pose some obstacles to achieving a robust mechanical design of the battery while also providing a high capacity and a stable or smooth voltage curve during charging and discharging.

[0005] When the battery is charged or discharged, a sufficient amount of electrolyte in close contact with the active material of the electrode can provide a smooth voltage curve when the battery is charged or discharged and maintain the power capability of the battery over time. However, the electrodes of a lithium battery may expand or contract during charging or discharging. The cathode of a lithium battery can expand up to 50% to 100% during the later stage of discharge. When the cathode expands, the porosity of the cathode increases. If the electrolyte cannot fill the expanded pores of the cathode, voids can form within the cathode. Such voids may cause the voltage of the battery to fluctuate irregularly and reduce the power capability and available capacity of the battery.

[0006] Such effects can be mitigated by increasing the amount of liquid electrolyte used to fill the battery and / or increasing the stacking pressure between the cathode and the anode. Such increases can singly or in combination result in a smoother voltage curve and a more robust power capability. However, as the amount of liquid electrolyte increases, the proportion of the active material of the battery decreases, which may result in a lower battery capacity or energy density. Additionally, an increase in stacking pressure may require a thicker and more rigid battery case, which may reduce the energy density and increase the total cost of the battery.

[0007] In addition, a low-viscosity liquid electrolyte can move more easily within the battery housing than a high-viscosity electrolyte. Such movement can cause the movement of lithium ions within the battery and result in uncontrolled lithium deposition on the inner surface of the battery case or housing and the electrode terminals. Additionally, such deposition may disrupt the insulation between the anode and the cathode. As a result, an increase in self-discharge of the battery may occur. Summary of the Invention

[0008] As described herein, a smooth voltage curve of a lithium battery including a liquid electrolyte can be achieved by including a gelled powder having a cathode material during cathode formation and then mixing the liquid electrode and the cathode material. Sequentially adding such a gelled powder and a liquid electrolyte to the cathode material can allow for the formation of a gelled electrolyte throughout the cathode material to provide a gelled cathode mixture prior to pressing or forming the cathode. Thus, a more uniform cathode including or incorporating a gelled electrolyte can be provided. Additionally, such a cathode can have a higher density, have fewer or smaller volume voids or cavities compared to a cathode formed using typical methods, and can be easier to manufacture. Furthermore, less electrolyte can be used in an electrochemical cell including a cathode having a gelled electrolyte, and free liquid electrolyte within the battery or electrochemical cell can be reduced.

[0009] Generally, in one aspect, the present disclosure describes a method of forming an electrochemical cell. The method includes grinding a cathode material to provide a cathode powder. The method further includes mixing a gelled powder with the cathode powder to provide a gelled cathode powder, and mixing a liquid electrolyte with the gelled cathode powder to provide a gelled cathode mixture. Additionally, the method can include pressing the gelled cathode mixture to form a cathode of the electrochemical cell.

[0010] Generally, in another aspect, the present disclosure describes a method of forming an electrochemical cell. The method includes mixing an active material, a conductive material, and a binder to provide a cathode slurry. The method further includes heating the cathode slurry to provide a dried cathode mixture, and grinding the dried cathode mixture to provide a cathode powder. The method further includes mixing a gelled powder with the cathode powder to provide a gelled cathode powder. The method further includes mixing a liquid electrolyte with the gelled cathode powder to provide a gelled cathode mixture. Additionally, the method can include pressing the gelled cathode mixture to form a cathode of the electrochemical cell.

[0011] Generally, in another aspect, the present disclosure describes an electrochemical cell that includes an anode, a cathode, a separator, and a liquid electrolyte. The cathode has a porosity of less than 20 volume %. The cathode includes an active material, a conductive material, a binder, and a gelled electrolyte. The separator is disposed between the anode and the cathode. The separator is configured to prevent direct contact between the anode and the cathode. The liquid electrolyte transports ions between the cathode and the anode.

[0012] Advantages and additional features of the subject matter of the present disclosure are set forth in the following detailed description, and, for those skilled in the art, these features and advantages will become partially apparent from the description or will be recognized by practicing the subject matter of the present disclosure as described herein, including the following detailed description, the claims, and the drawings.

[0013] It should be understood that both the foregoing general description and the following detailed description present embodiments of the subject matter of the present disclosure and are intended to provide an overview or framework for understanding the nature and characteristics of the subject matter of the present disclosure as claimed. The drawings are included to provide a further understanding of the subject matter of the present disclosure, and the drawings are incorporated into the specification and form a part of the specification. The drawings illustrate various embodiments of the subject matter of the present disclosure and, together with the description, are used to explain the principles and operations of the subject matter of the present disclosure. Additionally, the drawings and the description are intended to be illustrative only and are not intended to limit the scope of the claims in any way. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The following detailed description of specific embodiments of the present disclosure can be best understood when read in conjunction with the following drawings, in which:

[0015] Figure 1 is a schematic block diagram of an embodiment of an electrochemical cell;

[0016] Figure 2 is for forming Figure 1 a schematic flowchart of a method of an electrochemical cell;

[0017] Figure 3 is for forming Figure 1 a schematic flowchart of another method of an electrochemical cell; DETAILED DESCRIPTION

[0018] Reference will now be made in more detail to various embodiments of the subject matter of the present disclosure, some embodiments of the present disclosure being illustrated in the drawings. The same numbers are used in the drawings to refer to the same components and steps. However, it should be understood that using numbers to refer to components in a given drawing is not intended to limit the components marked with the same numbers in another drawing. Additionally, using different numbers to refer to components in different drawings is not intended to indicate that components with different numbers cannot be the same or similar to components with other numbers.

[0019] Reduction of unstable voltage variations and lithium plating can be achieved by adding a liquid electrolyte to a gelled cathode powder during cathode formation in an assembled lithium battery or electrochemical cell that includes a liquid electrolyte to provide a gelled cathode mixture. Reduction of unstable voltage variations can result in a smooth voltage curve for the lithium battery. The gelled cathode mixture of the formed cathode can cause the gelled electrolyte to be dispersed throughout the cathode, including the surface of the cathode. Thus, when the cathode expands, the gelled electrolyte can prevent or reduce void formation as the cathode expands during use. As a result, unstable voltage variations that may be caused by void formation can be eliminated or reduced. Accordingly, the voltage of the battery can vary smoothly as the battery is charged or discharged. Additionally, the resistance that is increased due to void formation can be reduced or eliminated. Thus, when the battery is charged or discharged, the ability of the battery to provide power in a burst or pulsed fashion can be unimpaired.

[0020] In addition, less liquid electrolyte can be used to fill the battery housing of the electrochemical cell while still reducing void formation, and thus the energy density of the battery can be increased and free liquid electrolyte within the battery can be reduced. Reduction of free liquid electrolyte can reduce lithium deposition, which can cause disruption of the insulation between the anode and cathode and an increase in self-discharge. Thus, forming the cathode using a gelled cathode mixture can reduce the likelihood of defects that result in an increase in self-discharge that may occur due to lithium deposition.

[0021] Furthermore, the gelled cathode mixture and the cathode formed from the gelled cathode mixture can have a more uniform composition compared to a cathode formed by mixing a gelled electrolyte with other cathode materials. Mixing a gelled electrolyte with a milled and dried cathode mixture or powdered cathode material may result in a lumpy cathode composition that is not suitable for cathode formation or pressing. Additionally, such mixing of a gelled electrolyte with a milled and dried cathode mixture may result in an extended manufacturing process and increased cost. In contrast, the gelled cathode mixture described herein can incorporate the gelled electrolyte throughout the dried cathode mixture or material and is suitable for cathode formation or pressing. Additionally, a cathode as described herein can be formed without using volatile solvents that are typically included in liquid electrolytes to aid in mixing the cathode materials.

[0022] Figure 1 A schematic illustration of an electrochemical cell 100 is shown. Electrochemical cell 100 includes an anode 102 (e.g., a negative electrode), a cathode 104 (e.g., a positive electrode), a liquid electrolyte 108, and a separator 106 (e.g., a polymeric microporous separator, indicated by the dashed lines).

[0023] The electrochemical cell 100 may include any suitable chemical substances. The chemical substances of the electrochemical cell 100 may include, for example, lithium-metal, lithium-ion, lithium-polymer, or other chemical substances that may suffer from cathode swelling problems. In at least one embodiment, the electrochemical cell 100 includes a lithium-ion battery cell. The electrochemical cell 100 may be a primary battery or a secondary battery. In other words, the electrochemical cell 100 may or may not be rechargeable.

[0024] The anode 102 may include any one or more suitable materials. Such materials may include, for example, one or more active materials, conductive materials, binders, or other suitable anode materials. The active material of the anode 102 may include, for example, one or more of carbon, graphite, silicon, lithium titanate, lithium, sodium, magnesium, or other negative electrode active substances. The conductive material of the anode 102 may include, for example, copper, gold, carbon, nickel, carbon black, graphene, carbon nanotubes, or other conductive materials. The binder of the anode 102 may include, for example, polyvinylidene fluoride (PVDF), poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP), styrene-butadiene rubber (SBR), carboxymethyl cellulose (CMC), or other materials for binding the anode materials together.

[0025] The cathode 104 may include any one or more suitable materials. Such materials may include, for example, one or more active materials, conductive materials, binders, gelling electrolytes, or other suitable cathode materials. The active material of the cathode 104 may include, for example, carbon fluoride, silver vanadate, lithium vanadate, manganese dioxide, vanadium dioxide, lithium cobalt oxide, lithium nickel-manganese-cobalt oxide, lithium nickel-cobalt-aluminum oxide, or other positive electrode active materials. In one or more embodiments, the active material of the cathode includes carbon fluoride and silver vanadium oxide. The conductive material of the cathode 104 may include, for example, copper, gold, carbon, nickel, carbon black, graphene, carbon nanotubes, or other conductive materials. The binder of the cathode 104 may include, for example, polyvinylidene fluoride (PVDF), poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP), styrene-butadiene rubber (SBR), carboxymethyl cellulose (CMC), poly(tetrafluoroethylene) (PTFE), or other materials for binding the cathode materials together.

[0026] The gelled electrolyte of the cathode 104 may comprise a gelling powder and a liquid electrolyte or be formed from a gelling powder and a liquid electrolyte. The gelling powder may include, for example, polyethylene oxide, polypropylene oxide, polyacrylonitrile, poly(methyl methacrylate), cellulose, or any other suitable gelling agent. The material of the gelling powder of the cathode 104 may be ground or otherwise processed to provide particles that are fine enough to be mixed with other powdered cathode materials. The gelling powder of the cathode may be configured to gel the liquid electrolyte added to other cathode materials in the cathode 104 or to become a gelled electrolyte. The gelled electrolyte may be dispersed throughout the cathode and may prevent the formation of voids or pores when the cathode 104 expands during the use of the electrochemical cell 100.

[0027] Additionally, the gelled electrolyte of the cathode 104 may allow for a greater cathode density than a typical electrochemical cell. For example, the cathode 104 may have a porosity of less than 20% by volume. In other words, the ratio of the volume of cracks (e.g., interstitial spaces, voids, etc.) in the cathode material to the volume of the cathode material mass is 1:4 or less. Further, for example, the cathode 104 may have a porosity of less than 15% by volume, 10% by volume, or 5% by volume. The cathode 104 may include any suitable amount of gelled electrolyte. In one or more embodiments, the cathode 104 may include 10 wt% to 20 wt% of the gelled electrolyte.

[0028] The electrodes 102, 104 may be provided in the form of relatively flat or planar plates, or may be wound or coiled in a spiral or other configuration (e.g., an oval configuration). The electrodes 102, 104 may also be provided in a folded configuration.

[0029] The separator 106 may be disposed between the anode 102 and the cathode 104. In other words, the separator 106 may be provided between or in the middle of the anode 102 and the cathode 104. The separator 106 may be configured to prevent direct contact between the anode 102 and the cathode 104. The separator 106 may also be configured to allow the transport of ionic charge carriers between the anode 102 and the cathode 104.

[0030] The separator 106 may be of any suitable size or shape. The separator 106 may be, for example, flat, planar, wound or coiled in a spiral, oval, or folded, or any other suitable shape for being disposed between the anode 102 and the cathode 104. Generally, the size or shape of the separator 106 may depend on or conform to the size or shape of the electrodes 102, 104. For example, when the electrodes 102, 104 are provided as planar plates, the separator 106 may be provided as relatively flat or planar. Additionally, for example, when the electrodes 102, 104 are provided in a wound or coiled configuration, the separator 106 may be provided in a coiled configuration to separate these electrodes.

[0031] The separator 106 can define a membrane forming the microporous layer. The separator 106 can include any one or more suitable materials. The separator 106 can include, for example, one or more of polymers, polyethylene, polypropylene, polyimide, cellulose, or other materials for forming the microporous layer.

[0032] The liquid electrolyte 108 can transport positively charged ions between the anode 102 and the cathode 104. The liquid electrolyte 108 can include any one or more suitable materials. The liquid electrolyte 108 can include one or more solutes. The solutes of the liquid electrolyte 108 can include, for example, lithium salts, lithium bis(trifluoromethylsulfonyl)imide (LiTFSI), lithium bis(pentafluoroethylsulfonyl)imide (LiBETI), lithium tris(trifluoromethylsulfonyl)methide, lithium perchlorate (LiClO4), lithium tetrafluoroborate (LiBF4), lithium hexafluoroarsenate (LiAsF6), lithium hexafluorophosphate (LiPF6), or other solutes capable of transporting ionic charge carriers. The gelled electrolyte of the cathode 104 can allow the liquid electrolyte 108 to be provided without using a volatile solvent. Typical solvents can include, for example, one or more of propylene carbonate, ethylene carbonate, dimethyl carbonate, dimethoxyethane, diethoxyethane, or other solvents. The liquid electrolyte 108 can be a low-viscosity liquid electrolyte. As used herein, the term "low viscosity" refers to a viscosity less than 50 centipoise. The viscosity of the liquid electrolyte 108 can be less than 10 centipoise. The viscosity of the liquid electrolyte 108 can be less than 5 centipoise. In one or more embodiments, the viscosity of the liquid electrolyte 108 is less than 2 centipoise. The electrochemical cell 100 can have an electrolyte weight to cathode weight ratio of 0.5 or less.

[0033] The electrochemical cell can further include a cell housing 118. The cell housing 118 of the electrochemical cell 100 can include any one or more suitable elastic materials. One or more elastic (e.g., puncture- and corrosion-resistant and chemically stable) materials can be configured to protect the internal components (e.g., anode 102, cathode 104, separator 106, liquid electrolyte 108, etc.) of the electrochemical cell 100. Such elastic materials can include, for example, nickel, steel, titanium, aluminum, or other elastic materials. The packaging can include any suitable packaging material or material for holding the internal components of the electrochemical cell 100 together in a predetermined shape. Such packaging materials can include plastics, ceramics, etc.

[0034] During charging and discharging of the electrochemical cell 100, lithium ions move between the anode 102 and the cathode 104. For example, when the electrochemical cell 100 is charged, lithium ions flow from the cathode 104 to the anode 102. Conversely, when the electrochemical cell 100 is discharged, lithium ions flow from the anode 102 to the cathode 104.

[0035] When the electrochemical cell 100 is charged or discharged, the cathode 104 can expand. A typical cathode usually includes pores or voids that can expand as such a cathode expands. However, in a typical lithium battery (or other battery chemistries), when the cathode and the pores expand, the liquid electrolyte may not fill the pores of the cathode, and thus voids may form in the pores of such a cathode. The voids are an interruption of the contact between the liquid electrolyte and the cathode, which may reduce the effective area of ion conduction between the liquid electrolyte and the cathode. Therefore, when the cathode expands and the ion conduction between the liquid electrolyte and the cathode fluctuates, such voids may cause unstable changes in the battery voltage and an increase in the resistance of the electrochemical cell 100. However, the cathode 104 of the electrochemical cell 100 includes a gelled electrolyte dispersed throughout the cathode 104.

[0036] The gelled electrolyte of the cathode 104 can eliminate or reduce the occurrence of any pores or voids in the cathode 104. Additionally, the gelled electrolyte of the cathode 104 can also reduce or eliminate the expansion of any pores or voids that may be included in the cathode 104. The gelled electrolyte of the cathode 104 can easily fill any pores or voids when expanded, thereby preventing or reducing void formation and maintaining a tight contact for ion conduction between the liquid electrolyte 108 and the cathode 104. Therefore, unstable changes in the voltage that may be caused by such voids are also prevented or reduced in the electrochemical cell 100. Additionally, the increase in resistance that may be caused by void formation can be eliminated or reduced, and the pulse power or capacity of the electrochemical cell 100 can be maintained during the entire battery charge or discharge.

[0037] Figure 2 A flowchart of a method or process 200 for forming a battery or an electrochemical cell unit (e.g., Figure 1 the electrochemical cell 100) is shown.

[0038] At 202, the cathode material can be ground to provide a cathode powder. Grinding the cathode material can provide a relatively uniform particle size distribution in the cathode powder. The cathode powder can have a particle size distribution between about 0.1 microns and about 1000 microns. In one embodiment, the cathode powder has an average particle size distribution of at least 100 microns to no greater than 200 microns.

[0039] The cathode material may include an active material, a conductive material, and a binder. Providing the cathode material before grinding may include mixing the cathode material with a solvent to form or provide a cathode slurry. The cathode slurry may be provided without using a volatile solvent. Any one or more suitable techniques may be used to mix the active material, the conductive material, and the binder. Such techniques may include, for example, mixing using a planetary mixer, a rotary mixer, or a helical mixer. Providing the cathode material may also include heating the cathode slurry to provide a dried cathode mixture. In other words, the cathode material may be provided as a dried cathode mixture. The cathode slurry may be heated to at least 100 degrees Celsius and not more than 200 degrees Celsius. Heating the cathode slurry may dry the cathode slurry. In other words, heating the cathode slurry may remove moisture that may be present in the cathode slurry.

[0040] At 204, the cathode material may be ground to provide a cathode powder. Grinding the dried cathode mixture may provide a relatively uniform particle size distribution in the cathode powder. The cathode powder may have a particle size distribution between about 0.1 micrometers and about 1000 micrometers. In one embodiment, the cathode powder has an average particle size distribution of at least 100 micrometers and not more than 200 micrometers. The cathode powder may be optionally heated. The cathode powder may be heated to at least 150 degrees Celsius and not more than 300 degrees Celsius. Heating the cathode powder may dry the cathode powder. In other words, heating the cathode powder may remove any residual moisture from the cathode powder.

[0041] At 206, the gelling powder may be mixed with the cathode powder to provide a gelled cathode powder. Mixing the gelling powder with the cathode powder may provide a more uniform mixture of the cathode material and the gelling powder compared to other stages in cathode formation. For example, the gelling powder may absorb water or other moisture during a previous step. Any one or more suitable techniques may be used to mix the gelling powder with the cathode powder. Such techniques may include, for example, using an acoustic mixer, a planetary mixer, a helical mixer, or other mixing equipment or techniques to mix the gelling powder with the cathode powder. The gelled cathode powder may include at least 0.1 wt% and not more than 10 wt% of the gelling powder. The gelled cathode powder may include at least 1 wt% and not more than 5 wt% of the gelled cathode powder. The gelled cathode powder may include at least 2 wt% and not more than 4 wt% of the gelling powder.

[0042] At 208, the gelled cathode powder may be mixed with a liquid electrolyte to provide a gelled cathode mixture. Any one or more suitable techniques may be used to mix the gelled cathode powder with the liquid electrolyte. Such techniques may include, for example, using an acoustic mixer, a planetary mixer, a helical mixer, or other mixing equipment or techniques to mix the gelled cathode powder with the liquid electrolyte. In one or more embodiments, mixing the liquid electrolyte with the gelled cathode powder includes using an acoustic mixer to mix the liquid electrolyte with the gelled cathode powder.

[0043] Method 200 may also include storing the gelled cathode mixture for a predetermined period of time. Storing the gelled cathode mixture may allow the gelled powder and the liquid electrolyte to form a gelled electrolyte throughout the gelled cathode mixture. The predetermined period of time may be at least 1 hour. In one or more embodiments, the predetermined period of time may be at least 1 hour and not more than 2 days, or any time range therebetween. The gelled cathode mixture may be stored at room temperature or up to 100 degrees Celsius. For example, the gelled cathode mixture may be stored at a temperature of at least 20 °C and not higher than 70 °C.

[0044] At 214, the gelled cathode mixture may be pressed to form a cathode (e.g., cathode 104) of an electrochemical cell. The gelled cathode mixture may be pressed into a current collector cup, onto a current collector, or into a mold to form the cathode. When pressed, the gelled cathode mixture may be subjected to a pressure of about 1000 psi to about 100000 psi.

[0045] Method 200 may also include disposing a liquid electrolyte (e.g., liquid electrolyte 108) in a housing (e.g., cell housing 118) of the electrochemical cell to transport ions between the anode (e.g., anode 102) and the cathode of the electrochemical cell. Additionally, method 200 may also include sealing the electrochemical cell.

[0046] Figure 3 A flowchart of a method or process 300 for forming a battery or an electrochemical cell unit (e.g., Figure 1 electrochemical cell 100) is shown.

[0047] At 302, an active material, a conductive material, a binder, and a solvent may be mixed to provide a cathode slurry. The cathode slurry may be provided without using any solvent. Any one or more suitable techniques may be used to mix the active material, the conductive material, and the binder. Such techniques may include, for example, mixing using a planetary mixer, a rotary mixer, or a helical mixer.

[0048] At 304, the cathode slurry may be heated to provide a cathode mixture. The cathode slurry may be heated to at least 100 degrees Celsius to not more than 200 degrees Celsius. Heating the cathode slurry may dry the cathode slurry. In other words, heating the cathode slurry may remove moisture that may be present in the cathode slurry.

[0049] At 306, the dried cathode mixture may be ground to provide a cathode powder. Grinding the dried cathode mixture may provide a relatively uniform particle size distribution in the cathode powder. The cathode powder may have a particle size distribution between about 0.1 micron and about 1000 microns. In one embodiment, the cathode powder has an average particle size distribution of at least 100 microns to not greater than 200 microns.

[0050] At 308, the cathode powder may optionally be heated. The cathode powder may be heated to at least 150 degrees Celsius and not more than 300 degrees Celsius. Heating the cathode powder may dry the cathode powder. In other words, heating the cathode powder may remove any residual moisture from the cathode powder.

[0051] At 310, the gelling powder may be mixed with the cathode powder to provide a gelled cathode powder. Mixing the gelling powder with the cathode powder may provide a more uniform mixture of the cathode material and the gelling powder compared to other stages in cathode formation. For example, the gelling powder may absorb water or other moisture during a previous step. Any one or more suitable techniques may be used to mix the gelling powder with the cathode powder. Such techniques may include, for example, using an acoustic mixer, a planetary mixer, a helical mixer, or other mixing equipment or techniques to mix the gelling powder with the cathode powder. The gelled cathode powder may include at least 0.1 wt% and not more than 10 wt% of the gelling powder. The gelled cathode powder may include at least 1 wt% and not more than 5 wt% of the gelled cathode powder. The gelled cathode powder may include at least 2 wt% and not more than 4 wt% of the gelling powder.

[0052] At 312, the gelled cathode powder may be mixed with a liquid electrolyte to provide a gelled cathode mixture. Any one or more suitable techniques may be used to mix the gelled cathode powder with the liquid electrolyte. Such techniques may include, for example, using an acoustic mixer, a planetary mixer, a helical mixer, or other mixing equipment or techniques to mix the gelled cathode powder with the liquid electrolyte. In one or more embodiments, mixing the liquid electrolyte with the gelled cathode powder includes using an acoustic mixer to mix the liquid electrolyte with the gelled cathode powder.

[0053] Method 300 may further include storing the gelled cathode mixture for a predetermined period of time. Storing the gelled cathode mixture may allow the gelling powder and the liquid electrolyte to form a gelled electrolyte throughout the gelled cathode mixture. The predetermined period of time may be at least 1 hour. In one or more embodiments, the predetermined period of time may be at least 1 hour and not more than 2 days, or any time range therebetween. The gelled cathode mixture may be stored at room temperature or up to 100 degrees Celsius. For example, the gelled cathode mixture may be stored at a temperature of at least 20°C and not higher than 70°C.

[0054] At 314, the gelled cathode mixture may be pressed to form a cathode (e.g., cathode 104) of an electrochemical cell. The gelled cathode mixture may be pressed into a current collector cup, onto a current collector, or into a mold to form the cathode. When pressed, the gelled cathode mixture may be subjected to a pressure of about 1000 psi to about 100000 psi.

[0055] Method 300 may further include disposing a liquid electrolyte (e.g., liquid electrolyte 108) within a housing of an electrochemical cell (e.g., cell housing 118) to transport ions between an anode (e.g., anode 102) and a cathode of the electrochemical cell. Additionally, method 300 may further include sealing the electrochemical cell.

[0056] The present invention is defined in the claims. However, an incomplete list of non-limiting examples is provided below. Any one or more features of these examples may be combined with any one or more features of another example, embodiment, or aspect described herein.

[0057] Example 1: A method of forming an electrochemical cell, the method comprising: mixing an active material, a conductive material, and a binder to provide a cathode slurry; heating the cathode slurry to provide a dried cathode mixture; milling the dried cathode mixture to provide a cathode powder; mixing a gelling powder with the cathode powder to provide a gelled cathode powder; mixing a liquid electrolyte with the gelled cathode powder to provide a gelled cathode mixture; and pressing the gelled cathode mixture to form a cathode of the electrochemical cell.

[0058] Example 2: The method according to Example 1, further comprising storing the gelled cathode mixture for at least 1 hour.

[0059] Example 3: The method according to any one of the preceding examples, further comprising storing the gelled cathode mixture for a predetermined period of time at a temperature between 20 degrees Celsius and 100 degrees Celsius.

[0060] Example 4: The method according to any one of the preceding examples, wherein mixing the liquid electrolyte with the gelled cathode powder comprises mixing the liquid electrolyte with the gelled cathode powder using an acoustic mixer.

[0061] Example 5: The method according to any one of the preceding examples, wherein the gelled cathode powder comprises 2 wt% to 4 wt% of the gelling powder.

[0062] Example 6: The method according to any one of the preceding examples, wherein the gelling powder comprises poly(ethylene oxide).

[0063] Example 7: The method according to any one of the preceding examples, wherein the conductive material comprises conductive carbon.

[0064] Example 8: The method according to any one of the preceding examples, forming an anode of the electrochemical cell, the anode comprising lithium.

[0065] Example 9: The method according to any one of the preceding examples, the method further comprising disposing a liquid electrolyte in the housing of the electrochemical cell to transport ions between the anode and the cathode of the electrochemical cell.

[0066] Example 10: The method according to any one of the preceding examples, wherein the liquid electrolyte comprises a lithium salt solution.

[0067] Example 11: The method according to any one of the preceding examples, wherein the liquid electrolyte has a viscosity of less than 10 centipoise.

[0068] Example 12: The method according to any one of the preceding examples, wherein the active material of the cathode comprises carbon fluoride and silver vanadium oxide.

[0069] Example 13: An electrochemical cell, the electrochemical cell comprising: an anode; a cathode, the cathode comprising a gelled cathode mixture, the gelled cathode mixture comprising: an active material; a conductive material; a binder; and a gelled electrolyte; a separator disposed between the anode and the cathode, the separator configured to prevent direct contact between the anode and the cathode; and a liquid electrolyte for transporting ions between the cathode and the anode.

[0070] Example 14: The electrochemical cell according to Example 13, wherein the porosity of the cathode is less than 20% by volume.

[0071] Example 15: The electrochemical cell according to any one of Examples 13 or 14, wherein the cathode comprises 10% to 20% by weight of the gelled electrolyte.

[0072] Example 16: The electrochemical cell according to any one of Examples 13 to 15, wherein the gelled electrolyte comprises poly(ethylene oxide).

[0073] Example 17: The electrochemical cell according to any one of Examples 13 to 16, wherein the conductive material comprises conductive carbon.

[0074] Example 18: The electrochemical cell according to any one of Examples 13 to 17, wherein the anode comprises lithium.

[0075] Example 19: The electrochemical cell according to any one of Examples 13 to 18, wherein the electrolyte comprises a lithium salt solution.

[0076] Example 20: The electrochemical cell according to any one of Examples 13 to 19, wherein the liquid electrolyte has a viscosity of less than 10 centipoise.

[0077] Example 21: The electrochemical cell according to any one of Examples 13 to 20, wherein the electrochemical cell has an electrolyte weight to cathode weight ratio of 0.5 or less.

[0078] Example 22: The electrochemical cell according to any one of Examples 13 to 21, wherein the active material of the cathode comprises carbon fluoride and silver vanadium oxide.

[0079] Example 23: A method of forming an electrochemical cell, the method comprising: grinding a cathode material to provide a cathode powder; mixing a gelling powder with the cathode powder to provide a gelled cathode powder; mixing a liquid electrolyte with the gelled cathode powder to provide a gelled cathode mixture; and pressing the gelled cathode mixture to form the cathode of the electrochemical cell.

[0080] Example 24: The method according to Example 23, further comprising storing the gelled cathode mixture for at least 1 hour.

[0081] Example 25: The method according to any one of Examples 23 to 24, further comprising storing the gelled cathode mixture for a predetermined period of time at a temperature between 20 degrees Celsius and 100 degrees Celsius.

[0082] Example 26: The method according to any one of Examples 23 to 25, wherein mixing the liquid electrolyte with the gelled cathode powder comprises using an acoustic mixer to mix the liquid electrolyte with the gelled cathode powder.

[0083] Example 27: The method according to any one of Examples 23 to 26, wherein the gelled cathode powder comprises 2 wt% to 4 wt% of the gelling powder.

[0084] Example 28: The method according to any one of Examples 23 to 27, wherein the gelling powder comprises polyethylene oxide.

[0085] Example 29: The method according to any one of Examples 23 to 28, wherein the cathode material comprises an active material and a conductive material.

[0086] Example 30: The method according to any one of Examples 23 to 29, forming the anode of the electrochemical cell, the anode comprising lithium.

[0087] Example 31: The method according to any one of Examples 23 to 30, the method further comprising disposing a liquid electrolyte in a housing of the electrochemical cell to transport ions between the anode and the cathode of the electrochemical cell.

[0088] Example 32: The method according to Example 31, wherein the liquid electrolyte comprises a lithium salt solution.

[0089] Example 33: The method according to any one of Examples 31 or 32, wherein the liquid electrolyte has a viscosity of less than 10 centipoise.

[0090] Example 34: The method according to any one of Examples 23 to 33, wherein the active material of the cathode comprises carbon fluoride and silver vanadium oxide.

[0091] Unless otherwise noted, all scientific and technical terms used herein have the meanings commonly used in the art. The definitions provided herein are intended to facilitate understanding of certain terms commonly used herein and are not intended to limit the scope of the present disclosure.

[0092] As used herein, unless the context clearly indicates otherwise, the singular forms "a / an" and "the" include plural referents. As used in this specification and the appended claims, the term "or" is generally used in its sense, including "and / or", unless the text clearly specifies otherwise. The term "and / or" means any one or all of the listed elements or any combination of any two or more of the listed elements.

[0093] Unless otherwise expressly stated, no method set forth herein is intended to be construed as requiring that its steps be performed in a particular order. Accordingly, where a method claim does not actually recite an order to be followed by its steps or where no particular order is otherwise specifically set forth in the claim or in the specification, no particular order should be inferred. Any single or multiple recited features or aspects in any claim may be combined with or permuted with any other recited feature or aspect in any other claim.

[0094] It will be apparent to those skilled in the art that various modifications and variations can be made to the inventive technology without departing from the spirit and scope of the present disclosure. Since those skilled in the art can make modifications, combinations, sub-combinations and variations of the disclosed embodiments incorporating the spirit and substance of the inventive technology, the inventive technology should be construed to include all things within the scope of the appended claims and their equivalents.

Claims

1. An electrochemical cell, the electrochemical cell comprises: an anode; a cathode, the cathode comprising a gelled cathode mixture, the gelled cathode mixture comprising: active material; conductive material; binder; and gelled electrolyte; a separator disposed between the anode and the cathode, the separator configured to prevent direct contact between the anode and the cathode; and a liquid electrolyte for transporting ions between the cathode and the anode.

2. The electrochemical cell according to claim 1, wherein the porosity of the cathode is less than 20% by volume.

3. The electrochemical cell according to claim 2, wherein the cathode comprises 10% to 20% by weight of the gelled electrolyte.

4. The electrochemical cell according to claim 3, wherein the gelled electrolyte comprises polyethylene oxide.

5. The electrochemical cell according to claim 4, wherein the conductive material comprises conductive carbon.

6. The electrochemical cell according to claim 5, wherein the anode comprises lithium.

7. The electrochemical cell according to any one of claims 1 to 5, wherein the electrolyte comprises a lithium salt solution.

8. The electrochemical cell according to any one of claims 1 to 5, wherein the liquid electrolyte has a viscosity of less than 10 centipoise.

9. The electrochemical cell according to any one of claims 1 to 5, wherein the electrochemical cell has an electrolyte weight to cathode weight ratio of 0.5 or less.

10. A method of forming an electrochemical cell, the method comprises: grinding cathode material to provide cathode powder; mixing gelled powder with the cathode powder to provide gelled cathode powder; mixing a liquid electrolyte with the gelled cathode powder to provide a gelled cathode mixture; and pressing the gelled cathode mixture to form the cathode of the electrochemical cell.

11. The method according to claim 10, the method further comprising storing the gelled cathode mixture at a temperature between 20 degrees Celsius and 100 degrees Celsius for at least 1 hour.

12. The method according to claim 10 or 11, wherein the gelled cathode powder comprises 2% to 4% by weight of the gelled powder.

13. The method according to any one of claims 10 to 12, wherein the gelled powder comprises polyethylene oxide, and wherein the cathode material comprises active material and conductive material.

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