Use of perforated electrodes in silicon dominated anode cells

Abstract

Systems and methods for using a perforated anode in a silicon-dominant anode, the battery can include a cathode, an electrolyte, and an anode, where the cathode and anode each include an active material on a current collector. One or both of the current collector and active material can be perforated. For example, the current collector can be perforated and / or both the current collector and active material can be perforated. The battery can include a stack of anodes and cathodes. Each cathode of the stack can be perforated and / or each anode of the stack can be perforated. Each cathode of the stack can include two layers of active material on each face of the cathode, where a first layer of the two layers of active material can be used for pre-lithiation of the battery anode. A second layer of the two layers can be used for lithium cycling of the battery.

Description

[0001] Cross Reference / Incorporation by Reference of Related Applications

[0002] This application claims priority to U.S. Patent Application No. 16 / 676,813, filed November 7, 2020. TECHNICAL FIELD

[0003] Aspects of the present disclosure relate to energy generation and storage. More particularly, certain embodiments of the present disclosure relate to methods and systems for using a perforated anode in a silicon-dominant anode battery. BACKGROUND

[0004] Conventional methods for battery electrodes can be expensive, cumbersome, and / or inefficient, e.g., they can be complex and / or time-consuming to implement, and can limit battery service life.

[0005] Other limitations and disadvantages of conventional and traditional approaches will become apparent to one of ordinary skill in the art through comparison of such approaches with aspects of the present disclosure as set forth in the remainder of this application with reference to the drawings. SUMMARY

[0006] Systems and / or methods for using a perforated anode in a silicon-dominant anode battery, substantially as shown in, and / or described with respect to, at least one of the figures, as more fully set forth in the claims.

[0007] These and other advantages, aspects and novel features of the present disclosure, as well as details of an illustrated embodiment thereof, will be more fully understood from the following description and drawings. BRIEF DESCRIPTION OF DRAWINGS

[0008] Figure 1 is a diagram of a battery with a perforated electrode in accordance with an example embodiment of the present disclosure.

[0009] Figure 2 illustrates an anode during lithiation in accordance with an example embodiment of the present disclosure.

[0010] Figure 3 illustrates a top view and a side view of a battery in accordance with an example embodiment of the present disclosure.

[0011] Figure 4 is a flowchart of a method for manufacturing a battery in accordance with an example embodiment of the present disclosure.

[0012] Figure 5 is a flowchart of an alternative method for manufacturing a battery in accordance with an example embodiment of the present disclosure.

[0013] Figure 6A perforated cathode during anode lithiation is illustrated according to example embodiments of the present disclosure.

[0014] Figure 7A and Figure 7B Two embodiments of a multi-layered cathode according to example embodiments of the present disclosure are illustrated.

[0015] Figure 8 Battery capacity of standard and perforated electrodes according to example embodiments of the present disclosure is illustrated.

[0016] Figure 9 Cycle life of standard and perforated electrodes according to example embodiments of the present disclosure is illustrated. DETAILED DESCRIPTION

[0017] Figure 1 A diagram of a battery with a perforated electrode according to example embodiments of the present disclosure. Referring to Figure 1 , a battery 100 is shown that includes a separator 103 sandwiched between an anode 101 and a cathode 105, and current collectors 107A and 107B. For clarity, perforations are not shown in Figure 1 , but are shown in Figure 6 to Figure 9 . Also shown is a load 109 coupled to the battery 100, illustrating a situation when the battery 100 is in a discharge mode. In the present disclosure, the term "battery" can be used to indicate a single electrochemical cell, a plurality of electrochemical cells formed into a module, and / or a plurality of modules formed into an assembly.

[0018] The development of portable electronic devices and the electrification of transportation has driven the demand for high performance electrochemical energy storage. Small scale (<100 Wh) to large scale (>10 KWh) devices use lithium ion batteries primarily due to the high performance of lithium ion (Li-ion) batteries over other rechargeable battery chemistries.

[0019] The anode 101 and cathode 105, along with the current collectors 107A and 107B, can include electrodes that can include plates or films within or housing an electrolyte material, where the plates can provide a physical barrier for housing the electrolyte as well as conductive contact to an external structure. In other embodiments, the anode / cathode plates are immersed in an electrolyte while the housing provides electrolyte containment. The anode 101 and cathode are electrically coupled to the current collectors 107A and 107B, which contain metal or other conductive material for providing electrical contact to the electrodes as well as physical support to the active materials when forming the electrodes.

[0020] Figure 1The configuration shown in the middle illustrates the battery 100 in a discharge mode, while in a charging configuration, a charger can be used in place of the load 109 to reverse the process. In one class of batteries, the separator 103 is typically a film material made of, for example, an electrically insulating polymer that prevents electrons from flowing from the anode 101 to the cathode 105, or vice versa, while being porous enough to allow ions to pass through the separator 103. Typically, the separator 103, cathode 105, and anode 101 materials are formed as sheets, films, or active material-coated foils, respectively. The sheets of cathode, separator, and anode are stacked or rolled in sequence with the separator 103 separating the cathode 105 from the anode 101 to form the battery 100. In some embodiments, the separator 103 is a sheet and typically employs a roll-to-roll method and stacking in its manufacture. In these methods, the anode, cathode, and current collector (e.g., electrode) can include films.

[0021] In exemplary cases, the battery 100 can contain a solid, liquid, or gel electrolyte. The separator 103 is preferably insoluble in typical battery electrolytes, such as a composition that can include ethylene carbonate (EC), fluoroethylene carbonate (FEC), propylene carbonate (PC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), and the like, as well as dissolved LiBF4, LiAsF6, LiPF6, and LiClO4, and the like. The separator 103 can be wetted or soaked with a liquid or gel electrolyte. Further, in exemplary embodiments, the separator 103 does not melt below about 100°C to 120°C and exhibits sufficient mechanical properties for battery applications. In operation, the battery can experience swelling and shrinking of the anode and / or cathode. In exemplary embodiments, the separator 103 can swell and shrink by at least about 5% to 10% without failing and can also be flexible.

[0022] The separator 103 can be porous enough so that, once wetted with, for example, a liquid or gel electrolyte, ions can pass through the separator. Alternatively (or additionally), even without significant porosity, the separator can absorb electrolyte by gelling or other methods. The porosity of the separator 103 is also typically not so porous as to allow the anode 101 and cathode 105 to pass electrons through the separator 103.

[0023] Anode 101 and cathode 105 comprise electrodes for battery 100, providing electrical connections to devices for transferring charge in charging and discharging states. For example, anode 101 can comprise silicon, carbon, or a combination of these materials. Typical anode electrodes comprise carbon materials, which include a current collector such as a copper sheet. Carbon is commonly used because carbon has excellent electrochemical properties and is also electrically conductive. Anodes currently used in rechargeable lithium-ion batteries typically have a specific capacity of about 200 milliampere hours per gram. Graphite, an active material used for most lithium-ion battery anodes, has a theoretical energy density of 372 milliampere hours per gram (mAh / g). In contrast, silicon has a high theoretical capacity of 4200 mAh / g. To increase the volumetric and gravimetric energy densities of lithium-ion batteries, silicon can be used as an active material for the cathode or anode. Silicon anodes can be formed from, for example, silicon composites with more than 50% silicon.

[0024] In an example case, anode 101 and cathode 105 store ions, such as lithium, for separating charge. In this example, an electrolyte carries positively charged lithium ions from anode 101 to cathode 105 in a discharging mode, for example as shown in Figure 1 and vice versa, in a charging mode, through separator 105. The movement of lithium ions creates free electrons in anode 101, which creates a charge at positive current collector 107B. Current then flows from the current collector through load 109 to negative current collector 107A. Separator 103 blocks the flow of electrons within battery 100, allows the flow of lithium ions, and prevents direct contact between the electrodes.

[0025] When battery 100 discharges and provides current, anode 101 releases lithium ions to cathode 105 via separator 103, creating an electron flow from one side to the other via coupled load 109. When the battery is charged, the opposite occurs, where lithium ions are released by cathode 105 and received by anode 101.

[0026] The materials selected for anode 101 and cathode 105 are important for the possible reliability and energy density of battery 100. The energy, power, cost, and safety of current lithium-ion batteries need to be improved in order to compete with internal combustion engine (ICE) technology, for example, and to allow widespread adoption of electric vehicles (EVs). With the development of high-capacity and high-voltage cathodes, high-capacity anodes, and functional non-flammable electrolytes with high-voltage stability and compatibility with electrode interfaces, lithium-ion batteries are achieved that have high energy density, high power density, and improved safety. Furthermore, it is advantageous to have materials with low toxicity as battery materials to reduce process costs and promote consumer safety.

[0027] The performance of electrochemical electrodes depends on many factors, but largely depends on the robustness of electrical contact between electrode particles and between the current collector and electrode particles. The electrical conductivity of silicon anode electrodes can be controlled by the incorporation of conductive additives with different morphological properties. Carbon black (Super P), vapor grown carbon fibers (VGCF), and mixtures of both have previously been incorporated individually into anode electrodes, resulting in improvements in anode performance. The synergistic interaction between the two carbon materials can facilitate electrical contact during the large volume changes of silicon anodes during charge and discharge.

[0028] Prior art lithium ion batteries typically employ graphite-dominant anodes as the intercalation material for lithium. With the demand for improved performance of lithium ion batteries, such as higher energy density and fast charging, silicon is added as an active material or even completely replaces graphite as the dominant anode material. Most electrodes in the industry that are considered "silicon anodes" are graphite anodes with a small amount (typically <20%) of silicon added. These graphite-silicon hybrid anodes must use graphite with a lower lithiation voltage compared to silicon; in order to use graphite, the silicon must be almost completely lithiated. Therefore, these electrodes do not have the advantages of silicon or silicon composite anodes, where the voltage of the electrode is relative to Li / Li + significantly higher than 0 V, and therefore lithium plating is not easily performed. Furthermore, these electrodes can have significantly higher excess capacity on silicon compared to the counter electrode, to further increase robustness to high rates.

[0029] Silicon-based anodes relative to Li / Li + with a lithiation / delithiation voltage plateau at about 0.3 V to 0.4 V, which keeps the open circuit potential, avoiding unwanted Li plating and dendrite formation. While silicon shows excellent electrochemical activity, achieving stable cycle life for silicon-based anodes is challenging due to the large volume change of silicon during lithiation and delithiation. The silicon regions can lose electrical contact to the anode, as the large volume change, combined with its low electrical conductivity, separates the silicon from the surrounding materials in the anode.

[0030] Furthermore, the large volume change of silicon exacerbates the formation of the solid electrolyte interphase (SEI), which can further lead to electrical insulation, resulting in capacity loss. The expansion and contraction of the silicon particles upon charge-discharge cycling causes pulverization of the silicon particles, which increases its specific surface area. With the intercycle silicon surface area change and increase, the SEI repeatedly disintegrates and recombines. As a result, the SEI accumulates around the pulverized silicon regions during cycling, becoming a thick, electronically and ionically insulating layer. This accumulated SEI increases the impedance of the electrode and decreases the electrode electrochemical reactivity, which is detrimental to cycle life.

[0031] The cathode in a lithium-ion battery is typically the source of lithium during operation, but some systems have an anode that sources the lithium and is often also used as the source during the first few charges of the battery (also known as formation). In most battery applications or designs, multiple cathodes are sandwiched together with multiple anodes, where in the simplest case there is one anode and one cathode. In some cases, the cathode may have active material on one side, while in other cases the cathode has active material on both sides in a stacked battery to better provide lithium. In a stacked battery where the cathode is the outer layer and is double-sided, the active material on the outer surface is completely wasted because the lithium cannot reach the anode. Alternatively, if a single-sided cathode is used for the outer cathode in a stacked battery, the manufacturing process is more complicated and expensive due to the use of two types of cathodes. This can be alleviated by using perforated electrodes, where the anode and cathode are formed on a perforated current collector, or alternatively, the perforations are formed in the manufactured electrode. This will refer to Figure 2 to Figure 7B Further shown.

[0032] Figure 2 An anode during lithiation according to an exemplary embodiment of the present disclosure is illustrated. Figure 2 , showing a current collector 201, a binder 203, and an active material 205. It should be noted that the binder 203 may or may not be present depending on the type of anode manufacturing process used, as the binder is not required in direct coating processes and, if present, may be applied before or after heat treatment. Furthermore, the layer thicknesses are not necessarily shown to scale, and the binder 203 is typically thin enough so that the active material 205 contacts the current collector 201 at various locations on the surface. In an exemplary embodiment, the anode active material 205 comprises silicon particles in a binder material and a solvent, wherein the active material is pyrolyzed to convert the binder into glassy carbon, which provides a structural framework around the silicon particles and also provides electrical conductivity. The binder 203 can be used to couple the active material to the current collector 201. The current collector 201 can comprise a metal film such as copper, nickel, or titanium, although other conductive foils can be used depending on the desired tensile strength. The current collector 201 can include electrode perforations formed therein to allow lithiation to pass through the side of the current collector 201 opposite the active material 205.

[0033] Figure 2Also illustrated are lithium particles that are grafted to and lithiated active material 205 when incorporated into a battery having a cathode, electrolyte, and separator (not shown). Lithium lithiation of a silicon-dominated anode causes expansion of the material, with horizontal expansion represented by the x and y axes and thickness expansion represented by the z axis, as shown. The current collector 201 has a thickness t, where thicker foils provide greater strength and, if the binder 203 is strong enough, limit expansion in the x and y directions, resulting in greater expansion in the z direction, thereby producing anisotropic expansion. For example, an exemplary thicker foil of copper can have a thickness greater than 10 μm, such as 20 μm, while a thinner foil of copper can have a thickness less than 10 μm, such as ~5 μm or less.

[0034] In an exemplary embodiment, where an adhesive is used, the adhesive 203 comprises a polymer such as polyimide (PI) or polyamide-imide (PAI) that provides bonding strength between the active material film 205 and the current collector 201 while also providing electrical contact with the current collector 201. Depending on the strength required, other adhesives can be used as long as they can provide bonding strength with sufficient conductivity after processing. If the adhesive 203 provides a stronger, more rigid bond, assuming the current collector is also strong, expansion in the x and y directions can be more limited. Conversely, a more flexible and / or thicker adhesive can allow for more xy expansion, reducing the anisotropic nature of the anode expansion.

[0035] The current collector 201 may include electrode through-holes formed therein to allow lithiation to pass through from the other side of the current collector 201 opposite to the active material 205. This will be referred to as Figure 3 to Figure 8 Further shown.

[0036] Figure 3 1 and 2 show a top view and a side view of a battery according to an exemplary embodiment of the present disclosure. Figure 3 , shows a battery 301 having an anode 305 and a cathode 307. In this example, the battery 301 comprises a button cell, but other types of batteries are also relevant, such as pouch, square, and cylindrical. Anode terminal 309 and cathode terminal 311 provide electrical contact with an external load coupled to the battery 301. Figure 3 In the example shown in FIG, there are two cathodes 307 surrounding a single anode 305, but any number of anodes and cathodes is possible. The battery 300 also includes a separator 313 for separating the anode and cathode while allowing lithium ions to pass through.

[0037] When multiple anodes and cathodes are stacked, active material can be formed on both sides of the current collector so that each cathode can lithiate two different anodes, one on each side. This can improve manufacturing and packaging efficiency to have active material on both sides of the current collector. However, for cathodes on the top and bottom of the stack, such as cathode 307 in Figure 3 , active material on the outside (e.g., cathode backside 307B) is almost impossible to use for battery operation. To this end, a single-sided cathode can be used to eliminate wasted cathode active material, but this means that for a stacked battery with multiple cathodes and anodes, two different types of cathodes will be used, which increases manufacturing cost and complexity.

[0038] In an example scenario, cathode 307 can include holes or perforations through their respective current collectors, or alternatively, holes can be formed through both the current collector and the active material. One example is to form the active material on a perforated current collector, and another example is to make holes in the finished anode and / or cathode. Reference is made to Figure 4 and Figure 5 for descriptions of battery manufacturing processes.

[0039] Figure 4 is a flowchart of a method for manufacturing a battery according to an example embodiment of the present disclosure. The method includes physically mixing together active material, conductive additive, and binder, and coating it directly on a current collector. This example method includes a direct coating process in which a slurry of an anode or cathode is coated directly on a copper foil using a binder such as CMC, SBR, sodium alginate, PAI, PI, and mixtures and combinations thereof. Another example method includes forming the active material on a substrate and then transferring to a current collector, as described with respect to Figure 5 .

[0040] In step 401, the raw electrode active materials can be mixed using a binder / resin (e.g., PI, PAI), solvent, and conductive carbon. For example, for the anode, graphene / VGCF (1:1 by weight) can be dispersed in NMP under sonication for, e.g., 45 to 75 minutes, followed by the addition of Super P (1:1:1 with VGCF and graphene) and additional sonication for, e.g., 45 to 75 minutes. Silicon powder with a desired particle size can then be dispersed in a polyamide acid resin (15% solids in N-methyl pyrrolidone (NMP)) in a ball mill at, e.g., 800 to 1200 rpm for a specified time, then a conjugated carbon / NMP slurry can be added and dispersed at, e.g., 1800 to 2200 rpm for, e.g., another predetermined time to achieve a slurry viscosity of 2000 to 4000 cP and a total solids content of about 30%. The particle size and mixing time can be varied to configure the density and / or roughness of the active material. Further, the cathode active material can be mixed in step 401, where the active material can include lithium cobalt oxide (LCO), lithium iron phosphate, lithium nickel cobalt manganese oxide (NMC), lithium nickel cobalt aluminum oxide (NCA), lithium manganese oxide (LMO), lithium nickel manganese spinel, or similar materials or combinations thereof, mixed with the binder described above for the anode active material.

[0041] In step 403, the anode or slurry can be coated on a copper foil. Similarly, the cathode active material can be coated on a foil material, e.g., aluminum. In one embodiment, the foil can include perforations through the material to allow for the flow-through of lithiation during battery operation.

[0042] The active material can undergo drying in step 405, resulting in a residual solvent content of less than 15%. In step 407, an optional calendering process can be used, where a series of hard compression rollers can be used to trim the film / substrate into a smooth and dense piece of material.

[0043] In step 409, the anode active material can be pyrolized by heating to 500 to 800C, such that the carbon precursor is partially or fully converted to glassy carbon. In cases where the anode is heated at 400 degrees Celsius or above, the pyrolization step can result in an anode active material having a silicon content greater than or equal to 50% by weight. The pyrolization can be performed in the form of a roll, or after the punching in step 411. If performed in the form of a roll, the punching is performed after the pyrolization process. In cases where the current collector foil is not pre-punched / pre-perforated, the formed electrode can be perforated with, for example, a punching roll. The perforated electrode can then be sandwiched with a separator and electrolyte to form a battery. In step 413, the battery can undergo a formation process including initial charging and discharging steps to lithiate the anode, with some residual lithium remaining, and the battery capacity can be evaluated. The perforations in the electrode allow lithium to flow from the double-sided cathode to the anode, even if one side of the cathode does not face the anode, thereby increasing the battery capacity.

[0044] Figure 5 is a flow chart of an alternative method for manufacturing a battery according to exemplary embodiments of the present disclosure. While the previous method of manufacturing a composite electrode employed a direct coating process, this method physically mixes the active material, conductive additive, and binder together and is combined with a peeling and lamination process.

[0045] This method is illustrated in the flow chart of Figure 5 begins with step 501, in which the active material can be mixed with a binder / resin (e.g., polyimide (PI) or polyamide-imide (PAI)), a solvent, a silo silazane additive, and optionally a conductive carbon. As with the method described in Figure 4 graphene / VGCF (1 : 1 by weight) can be dispersed in NMP under sonication for, for example, 45 to 75 minutes, followed by the addition of Super P (1 : 1 : 1 with VGCF and graphene) and additional sonication for, for example, 45 to 75 minutes. Silicon powder having a desired particle size can then be dispersed in a polyamide acid resin (15% solids in N-methyl pyrrolidone (NMP)) in a ball mill at, for example, 1800 to 1200 rpm for a specified time, a conjugated carbon / NMP slurry can then be added and dispersed at, for example, 1800 to 2200 rpm for, for example, another predetermined time to achieve a slurry viscosity of 2000 to 4000 cP and a total solids content of about 30%. The particle size and mixing time can be varied to configure the density and / or roughness of the active material.

[0046] Additionally, the cathode active material can be mixed in step 501, where the active material can include lithium cobalt oxide (LCO), lithium iron phosphate, lithium nickel cobalt manganese oxide (NMC), lithium nickel cobalt aluminum oxide (NCA), lithium manganese oxide (LMO), lithium nickel manganese spinel, or similar materials or combinations thereof, mixed with the binder described above for the anode active material.

[0047] In step 503, the slurry can be coated on a polymer substrate, such as polyethylene terephthalate (PET), polypropylene (PP), or Mylar. The slurry can be coated on a PET / PP / Mylar film at a loading of 3 to 4 mg / cm 2 with 15% solvent content, and then dried in step 505 to remove a portion of the solvent. An optional calendering process can be used, where a series of hard rollers can be used to trim the film / substrate into a smooth and dense piece of material.

[0048] In step 507, the green film can then be removed from the PET, where the active material can be peeled off the polymer substrate, the peeling process being optional for polypropylene (PP) substrates as PP can leave ~2% carbon residue upon pyrolysis. After peeling, a curing and pyrolysis step 509 can be performed, where the film can be cut into pieces and vacuum dried using a two-stage method (100 to 140°C for 12 to 18 hours, 200 to 240°C for 4 to 6 hours). The dry film can be heat treated at 800 to 1200°C to convert the polymer matrix into carbon. The pyrolysis step can result in an anode active material having a silicon content greater than or equal to 50% by weight in the case where the anode is heated at 400 degrees Celsius or above.

[0049] In step 511, the pyrolyzed material can be flat or roll laminated onto a current collector, where, for example, for an anode, a copper foil can be coated with a nominal loading of 0.4 to 0.6 mg / cm 2 of polyamide-imide (applied as a 6 wt% varnish in NMP, vacuum dried at 100 to 140°C for 14 to 18 hours), while for a cathode, the active material can be laminated onto an aluminum foil. The foils can include perforations. A heated hydraulic press (40 to 60 seconds, 250 to 450°C, and 3000 to 5000 psi) can be used to laminate the silicon-carbon composite film onto the coated foils, thereby forming the final silicon composite electrode. In another embodiment, the pyrolyzed material can be roll laminated to the current collector. In the case where the current collector is not perforated prior to lamination with the active material, the completed electrode can be perforated, for example, using a punching process.

[0050] In step 513, the electrodes can then be sandwiched with the separator and cathode to form a battery. The battery can undergo a formation process including initial charge and discharge steps to lithiate the anode, with some residual lithium remaining, and the battery capacity can be evaluated. The perforations in the electrodes allow lithium to flow from the double-sided cathode to the anode, even if one side of the cathode is not facing the anode, thereby increasing the battery capacity.

[0051] Figure 6 A perforated cathode during anode lithiation is illustrated according to an example embodiment of the disclosure. Referring to Figure 6 , an anode 610 and a cathode 620 are shown. The anode 610 includes a current collector 609 and active materials 611A and 611B, with no adhesive shown but which can be present between the active materials 611A and 611B and the current collector 609 depending on the manufacturing process used. The cathode 620 includes a current collector 603 and active materials 605A and 605B. As in previous figures, the layer thicknesses are not necessarily to scale. Figure 1 As in previous figures, the layer thicknesses are not necessarily to scale.

[0052] In the example shown, the cathode 620 has perforations through the entire electrode, but in other examples the perforations can be only in the current collector 603. Further, the anode 610 is illustrated as not being perforated, as it can be sandwiched by cathodes on both sides (not shown), but alternatively the anode can also be perforated, as shown in the inset, with an alternative anode 630 showing perforations similar to the cathode 620.

[0053] In an example scenario where the cathode 620 is a top or bottom electrode of a battery stack (meaning that no other electrodes are located outside of it), the perforations 607 can allow lithium to travel from the active material 605B to the anode 610, increasing the capacity of the battery, as without the perforations any active material on the back side, i.e. active material 605B, would not be available for battery operation. Although the electrode perforations 607 are shown as holes through the structure, other structures are possible, such as a mesh foil or an expanded foil with a chain-link fence-like pattern. In example embodiments, the perforated area of the anode and cathode can be 0.1% to 40% of the electrode area.

[0054] The active material 605B can be a source of lithium for pre-lithiation of the battery. Various factors can allow lithium to travel from this layer throughout the battery. One is the formation charge rate, where a slower charge rate at 1C can improve this pre-lithiation. Further, higher temperatures during formation (e.g. greater than 50°C) can improve the diffusion of lithium, and higher cycle counts at low charge rates and higher temperatures can be used.

[0055] Figure 7A and Figure 7B Two examples of a multi-layered cathode according to example embodiments within the disclosure are illustrated. Referring toFigure 7A , shows an electrode 710 that includes a current collector 703 and a pair of active layers on each side, active layer 1 705A and active layer 2 707A on one side, and active layer 1 705B and active layer 2 707B on the other side. In an exemplary embodiment, one active layer on each side can include a pre-lithiation source, while the other active layer on each side includes lithium that circulates during normal operation of the battery. The loading, or amount of material per area, can be configured in each layer for different functions (e.g., pre-lithiation or cycling).

[0056] refer to Figure 7B , shows an electrode 720 comprising two current collectors 703A and 703B and an active layer on each side, each current collector having active layer 1 705A or 705B on one side and active layer 2 707A or 707B on the other side. In an exemplary embodiment, one active layer on each side may include a pre-lithiation source, while the other active layer on each side includes lithium that circulates during normal operation of the battery. The loading or amount of material per area can be configured in each layer for different functions (e.g., pre-lithiation or cycling).

[0057] This multilayer electrode stacking and controlled formation can enable precise configuration of available lithium throughout the battery. This can greatly improve battery capacity and energy density. Figure 6 As described in, in exemplary embodiments, the perforated area of ​​the electrode can be 0.1% to 40% of the electrode area.

[0058] Figure 8 The battery capacities of the standard electrode and the perforated electrode according to an exemplary embodiment of the present disclosure are illustrated. Figure 8 , shows a plot of the battery capacity of two-layer button cells with no perforation (control, Group 1), a perforated cathode and an unperforated anode (Group 2), and a perforated anode and a perforated cathode (Group 3). As can be seen, the capacity of the perforated cathode cells in Group 2 increased significantly compared to the non-perforated electrodes in Group 1, from ~8 mAh to ~11 mAh. For Group 3, in which both electrodes were perforated, the increase was smaller, which may be due to the excess capacity of the anode, where the cathode limits the battery capacity, so improving the anode does not significantly change the capacity. However, anode perforation can further increase the energy density of the battery and make more efficient use of the active material.

[0059] Figure 9 The cycle life of a standard electrode and a perforated electrode according to an exemplary embodiment of the present disclosure is illustrated. Figure 9 , shows a plot of the normalized capacity of Group 1 (no perforated electrode), Group 2 (perforated cathode), and Group 3 (perforated anode and cathode).

[0060] The perforated electrode cells of Group 2 and Group 3 were very similar to each other, but both were much better than the control Group 1, with significantly better cycle life. The cells were cycled with 1C charge to 4.2 V and 1C discharge to 2.5 V. The perforated electrode cells retained over 80% capacity after 250 cycles, while the control group without perforated electrodes dropped to 75% capacity after ~175 cycles.

[0061] In example embodiments of the disclosure, methods and systems for using perforated anodes in silicon-dominant anode cells are described. The cells can include a cathode, an electrolyte, and an anode, where the cathode and anode each include active materials on a current collector. One or both of the current collector and active materials can be perforated. For example, the current collector can be perforated and / or both the current collector and active materials can be perforated. The cells can include a stack of anodes and cathodes. Each cathode of the stack can be perforated and / or each anode of the stack can be perforated. Each cathode of the stack can include two layers of active materials on each face of the cathode, where a first layer of the two layers of active materials can be used for prelithiation of the anode of the cell. A second layer of the two layers can be used for lithium cycling of the cell. A formation process of the cell can be performed at a charge rate less than 1C. The active material of the anode can include 50% or more silicon by weight.

[0062] An outer surface of an outermost cathode of the stack can include active materials for prelithiating silicon-dominant anodes in the cell. Each cathode of the stack can include a first type of active material on a first surface of the cathode and a second type of active material on a second surface of the cathode, where the first type of active material is used for prelithiating silicon-dominant anodes of the cell and the second type of active material is used for lithium cycling of the cell. Each cathode of the stack can include two current collectors, each current collector having a first type of active material on a first surface of the current collector and a second type of active material on a second surface of the current collector, where the first type of active material is used for prelithiating silicon-dominant anodes of the cell and the second type of active material is used for lithium cycling of the cell.

[0063] As used herein, “and / or” means any one or more of the items in the list joined by “and / or.” As an example, “x and / or y” means any one of the three-element sets {(x), (y), (x, y)}. In other words, “x and / or y” means “one or both of x and y.” As another example, “x, y, and / or z” means any one of the seven-element sets {(x), (y), (z), (x, y), (x, z), (y, z), (x, y, z)}. In other words, “x, y, and / or z” means “one or more of x, y, and z.” As used herein, the term “exemplary” means serving as a non-limiting example, instance, or illustration. As used herein, the terms “e.g.,” and “for example” set off a list of one or more non-limiting examples, instances, or illustrations. As used herein, a battery, circuit, or device “operable” to perform a function when the battery, circuit, or device includes the hardware and code (if applicable) necessary to perform that function, regardless of whether the function is enabled or disabled (e.g., by a user-configurable setting, factory trim, configuration, etc.).

[0064] While the application has been described with reference to certain implementations, it will be understood by those skilled in the art that various changes can be made and equivalents can be substituted for elements thereof without departing from the scope of the application. In addition, many modifications can be made to adapt a particular situation or material to the teachings of the application without departing from the scope thereof. Therefore, it is intended that the application not be limited to the particular implementation disclosed, but that the application will include all implementations falling within the scope of the appended claims.

Claims

1. A battery, the battery comprising: a cathode, an electrolyte, and a silicon-dominant anode, the anode comprising an active material on a current collector, and the cathode comprising a first current collector and a second current collector, wherein the current collector of the anode and / or the first and second current collectors of the cathode are perforated; the cathode comprises a first type of active material on a first surface of the first and second current collectors and a second type of active material on a second surface of the first and second current collectors; the first and second types of active material comprise lithium cobalt oxide, lithium iron phosphate, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium manganese oxide, lithium nickel manganese spinel, or a combination thereof; the first type of active material is a pre-lithiation source of lithium for the silicon-dominant anode of the battery, and the second type of active material is for lithium cycling of the battery; wherein the battery comprises a stack of anodes and cathodes, an outer surface of an outermost cathode of the stack comprising the first type of active material.

2. The battery of claim 1, wherein both the current collector and active material are perforated.

3. The battery of claim 1, wherein each cathode of the stack is perforated.

4. The battery of claim 1, wherein each anode of the stack is perforated.

5. The battery of claim 1, wherein each cathode of the stack comprises the first type of active material on a first surface of the cathode and the second type of active material on a second surface of the cathode.

6. The battery of claim 1, wherein each cathode comprises two current collectors, each current collector having the first type of active material on a first surface of the current collector and the second type of active material on a second surface of the current collector.

7. The battery of claim 1, wherein each cathode of the stack comprises two layers of active material on each face of the cathode.

8. The battery of claim 7, wherein a first of the two layers of active material on each face of the cathode is for pre-lithiation of the silicon-dominant anode of the battery, and a second of the two layers on each face of the cathode is for lithium cycling of the silicon-dominant anode of the battery.

9. The battery of claim 1, wherein the active material of the anode comprises 50% or more silicon by weight.

10. The battery of claim 1, wherein a formation process of the battery is performed at a charge rate of less than 1C.

11. A method of forming a battery, the method comprising: forming a battery, the battery comprising a cathode, an electrolyte, and a silicon-dominant anode, the anode comprising an active material on a current collector, and the cathode comprising a first current collector and a second current collector, wherein the current collector of the anode and / or the first and second current collectors of the cathode are perforated; the cathode comprises a first type of active material on a first surface of the first and second current collectors and a second type of active material on a second surface of the first and second current collectors; The first and second types of active materials include lithium cobalt oxide, lithium iron phosphate, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium manganese oxide, lithium nickel manganese spinel, or a combination thereof; The first type of active material is a source of lithiation for prelithiation of silicon-dominant anodes of the battery, and the second type of active material is for lithium cycling of the battery; wherein the battery includes a stack of anodes and cathodes, an outer surface of an outermost cathode of the stack includes the first type of active material.

12. The method of claim 11, wherein both the current collector and active material are perforated.

13. The method of claim 11, wherein each cathode of the stack is perforated.

14. The method of claim 11, wherein each cathode of the stack includes the first type of active material on a first surface of the cathode and the second type of active material on a second surface of the cathode.

15. The method of claim 11, wherein each cathode includes two current collectors, each current collector having the first type of active material on a first surface of the current collector and the second type of active material on a second surface of the current collector.

16. The method of claim 11, wherein each anode of the stack is perforated.

17. The method of claim 11, wherein each cathode of the stack includes two layers of active material on each face of the cathode.

18. The method of claim 17, wherein a first of the two layers of active material on each face of the cathode is for prelithiation of silicon-dominant anodes of the battery, and a second of the two layers on each face of the cathode is for lithium cycling of silicon-dominant anodes of the battery.

19. The method of claim 11, wherein a formation process of the battery is performed at a charge rate of less than 1C.

20. A battery, the battery comprising: a battery including a plurality of cathodes, an electrolyte, and a plurality of silicon-dominant anodes, the anodes including active material on a current collector, and the cathodes including a first current collector and a second current collector, wherein one or more of the plurality of cathodes are perforated over less than 40% of an area of the cathode, and a silicon content of the anodes is at least 50% by weight of silicon, the cathodes including a first type of active material on a first surface of the first and second current collectors and a second type of active material on a second surface of the first and second current collectors; the first and second types of active materials include lithium cobalt oxide, lithium iron phosphate, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium manganese oxide, lithium nickel manganese spinel, or a combination thereof; the first type of active material is a source of lithiation for prelithiation of silicon-dominant anodes of the battery, and the second type of active material is for lithium cycling of the battery; wherein the battery includes a stack of anodes and cathodes, an outer surface of an outermost cathode of the stack includes the first type of active material.

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