Cell formation system for batteries

Abstract

A cell forming system for lithium-based secondary batteries includes a battery tray and a forming base. The battery tray includes a base and a population of battery slots configured to hold lithium-based secondary batteries with first and second terminals extending through the base of the battery tray. The forming base is configured to attach to the battery tray. The forming base includes connector groups and pre-lithiation modules. Each connector group is configured to make electrical contact with the first and / or second terminals of a different one of the lithium-based secondary batteries in the battery tray. Each pre-lithiation module is electrically connected to at least one connector group, and each pre-lithiation module is configured to diffuse lithium into an electrode active material of a lithium-based secondary battery connected to the connector group.

Description

[Technical field]

[0001] The field of the disclosure relates generally to the formation of secondary batteries, and more specifically to cell formation systems for lithium-based secondary batteries. [Background technology]

[0002] In a rocking chair battery cell, both the positive and negative electrodes of the secondary battery contain a material into which carrier ions, such as lithium, can be inserted and extracted. When the battery is discharged, carrier ions are extracted from the negative electrode and inserted into the positive electrode. When the battery is charged, carrier ions are extracted from the positive electrode and inserted into the negative electrode.

[0003] Silicon has become a promising candidate to replace carbonaceous materials as anodes due to its high specific capacity. For example, a graphite anode formed from LiC6 can have a specific capacity of about 370 milliampere-hours per gram (mAh / g), while a Li 15 Crystalline silicon anodes formed from Si4 can have a specific capacity of about 3600 mAh / g, nearly 10 times higher than graphite anodes. However, the use of silicon anodes has been limited due to the large volume change (e.g., 300%) of silicon when Li carrier ions are inserted into the silicon anode. This volume increase, together with the cracking and pulverization associated with charge and discharge cycles, has limited the practical use of silicon anodes. In addition, the use of silicon anodes has been limited due to their poor initial coulombic efficiency (ICE), which leads to capacity loss during the initial formation of secondary batteries utilizing silicon anodes.

[0004] After a lithium-based secondary battery is assembled, the assembled battery is typically subjected to a formation process. During the formation process, the battery is slowly charged and discharged one or more times. At least some known formation processes include a pre-lithiation process to add lithium to the battery. These formation processes are typically performed by large-scale centralized systems. Such systems include a central control center connected to all the batteries undergoing the formation process. The central control center directly controls the charging, discharging, and (where applicable) pre-lithiation of all the batteries to which it is connected. To control the formation process and enable the distribution of power to a large number of batteries, the central control center is a relatively large and expensive system that uses a significant amount of power, occupies a significant amount of space, and utilizes a large number of wires to connect to all of the batteries undergoing formation. Summary of the Invention

[0005] One aspect of the disclosure is a cell formation system for lithium-based secondary batteries. Each lithium-based secondary battery includes a bilayer population, an electrode busbar, a counter electrode busbar, an enclosure surrounding the bilayer population, the electrode busbar, and the counter electrode busbar, a first terminal electrically connected to the electrode busbar and extending from the enclosure, and a second terminal electrically connected to the counter electrode busbar and extending from the enclosure. Each bilayer of the bilayer population includes an electrode structure, a separator structure, and a counter electrode structure. The electrode structure of each member of the bilayer population includes an electrode current collector and an electrode active material layer, and the counter electrode structure of each member of the bilayer population includes a counter electrode current collector and a counter electrode active material layer. The cell formation system includes a battery tray and a forming base. The battery tray has a side surface population and a base connected to the side surface population. The battery tray includes a population of battery slots above the base, each battery slot of the population of battery slots configured to hold one lithium-based secondary battery with first and second terminals extending through the battery tray base to a position accessible from an underside of the battery tray base. The forming base is configured to attach to the battery tray from an underside of the battery tray base. The forming base includes a population of connector groups and a population of pre-lithiated modules, each connector group of the population of connector groups configured to make electrical contact with at least one of the first and second terminals of a different one of the lithium-based secondary batteries in the battery tray. Each pre-lithiated module of the population of pre-lithiated modules is electrically connected to at least one connector group, and each pre-lithiated module is configured to diffuse lithium into an electrode active material of a lithium-based secondary battery connected to the connector group to which the pre-lithiated module is electrically connected.

[0006] Another aspect of the disclosure is a method of forming cells for lithium-based secondary batteries. Each lithium-based secondary battery includes a bilayer assembly, an electrode bus bar, a counter bus bar, an enclosure surrounding the bilayer assembly, the electrode bus bar, and the counter bus bar, a first terminal electrically connected to the electrode bus bar and extending from the enclosure, and a second terminal electrically connected to the counter bus bar and extending from the enclosure. Each bilayer in the bilayer assembly includes an electrode structure, a separator structure, and a counter electrode structure. The electrode structure of each member of the bilayer assembly includes an electrode current collector and an electrode active material layer, and the counter electrode structure of each member of the bilayer assembly includes a counter electrode current collector and a counter electrode active material layer.The method includes: (i) loading a population of lithium based secondary batteries into a battery tray, the battery tray having a population of side surfaces and a base connected to the population of side surfaces, the battery tray including a population of battery slots on an upper side of the base, each battery slot of the population of battery slots configured to hold one lithium based secondary battery of the population of lithium based secondary batteries with a first terminal and a second terminal extending through the battery tray base to a position accessible from an underside of the battery tray base; and (ii) attaching a forming base to the battery tray from an underside of the battery tray base to form a formed assembly, the forming base including a population of connector groups and a population of pre-lithiated modules, each connector group of the population of connector groups being connected to an underside of the battery tray base. (iii) mounting the forming assembly in a forming station, (iv) buffering the population of lithium-based secondary batteries in the forming assembly using the pre-lithiation modules, (v) removing the forming base from the battery tray, and (vi) performing additional processes on the population of lithium-based secondary batteries in the battery tray, wherein each pre-lithiation module of the population of pre-lithiation modules is electrically connected to at least one of the first terminal and the second terminal of a different one of the lithium-based secondary batteries, and each pre-lithiation module is electrically connected to at least one connector group, and each pre-lithiation module is configured to diffuse lithium into an electrode active material of a lithium-based secondary battery connected to the connector group to which the pre-lithiation module is electrically connected; (iii) positioning the forming assembly in a forming station; (iv) buffering the population of lithium-based secondary batteries in the forming assembly using the pre-lithiation modules; (v) removing the forming base from the battery tray; and (vi) performing additional processes on the population of lithium-based secondary batteries in the battery tray.

[0007] Another aspect of the disclosure is a cell formation system for lithium-based secondary batteries. Each lithium-based secondary battery includes a bilayer population, an electrode busbar, a counter busbar, an enclosure surrounding the bilayer population, the electrode busbar, and the counter busbar, a first terminal electrically connected to the electrode busbar and extending from the enclosure, and a second terminal electrically connected to the counter busbar and extending from the enclosure. Each bilayer of the bilayer population includes an electrode structure, a separator structure, and a counter electrode structure. The electrode structure of each member of the bilayer population includes an electrode current collector and an electrode active material layer, and the counter electrode structure of each member of the bilayer population includes a counter electrode current collector and a counter electrode active material layer. The cell formation system includes a battery tray and a forming base. The battery tray has a side surface population and a base connected to the side surface population. The battery tray includes a population of battery slots on an upper side of a base, each battery slot of the population of battery slots configured to hold one lithium-based secondary battery with a first terminal and a second terminal extending through the battery tray base to a position accessible from an underside of the battery tray base. The forming base is configured to attach to the battery tray from an underside of the battery tray base. The forming base includes a population of connector groups and a population of forming clusters. Each connector group of the population of connector groups is configured to make electrical contact with at least one of the first terminal and the second terminal of a different one of the lithium-based secondary batteries in the battery tray. Each forming cluster includes a charging module connected to one of the connector groups and configured to charge the lithium-based secondary battery connected to the connector group, a pre-lithiation module connected to one of the connector groups and configured to diffuse lithium into an electrode active material layer of the lithium-based secondary battery connected to the connector group, and a discharging module connected to one of the connector groups and configured to discharge the lithium-based secondary battery connected to the connector group.

[0008] Yet another aspect is a method of cell formation system for lithium-based secondary batteries. Each lithium-based secondary battery includes a bilayer population, an electrode bus bar, a counter bus bar, an enclosure surrounding the bilayer population, the electrode bus bar, and the counter bus bar, a first terminal electrically connected to the electrode bus bar and extending from the enclosure, and a second terminal electrically connected to the counter bus bar and extending from the enclosure. Each bilayer in the bilayer population includes an electrode structure, a separator structure, and a counter electrode structure. The electrode structure of each member of the bilayer population includes an electrode current collector and an electrode active material layer, and the counter electrode structure of each member of the bilayer population includes a counter electrode current collector and a counter electrode active material layer. The method includes (i) loading at a first location a population of battery trays, each battery tray having a population of lithium-based secondary batteries, each battery tray configured to hold its population of lithium-based secondary batteries with first and second terminals extending through the battery tray to a position accessible from an underside of the battery tray; (ii) transporting the population of battery trays to a second location having at least one charging station; (iii) positioning the battery trays in the charging station; (iv) charging the population of lithium-based secondary batteries in the battery trays at the charging station; (v) removing the battery trays from the charging station; and (vi) forming a base on the battery trays. and mounting a population of pre-lithiated modules, each battery tray having a different forming base mounted thereto, each forming base including a population of connector groups and a population of pre-lithiated modules, each connector group of the population of connector groups configured to make electrical contact with at least one of a first terminal and a second terminal of a different one of the lithium-based secondary batteries in the battery tray, each pre-lithiated module of the population of pre-lithiated modules being electrically connected to at least one connector group, each pre-lithiated module being configured to diffuse lithium into an electrode active material of a lithium-based secondary battery connected to the connector group to which the pre-lithiated module is electrically connected;(vii) transporting the battery tray with the attached forming base to a third location having at least one forming station; (viii) positioning the battery tray with the attached forming base in the forming station; (ix) buffering the population of lithium-based secondary batteries in the battery tray using a pre-lithiation module in the forming base; (x) removing the battery tray with the attached forming base from the forming station; (xi) removing the forming base from the battery tray; (xii) transporting the battery tray to a fourth location; and (xiii) performing additional processes on the population of lithium-based secondary batteries in the battery tray at the fourth location.

[0009] Various refinements exist on the features mentioned in relation to the above aspects. Further features may be incorporated into the above aspects. These refinements and additional features may exist individually or in any combination. For example, various features discussed below in relation to any of the illustrated embodiments may be incorporated alone or in any combination into any of the above aspects. [Brief description of the drawings]

[0010] [Figure 1] FIG. 2 is a perspective view of an exemplary embodiment of a secondary battery. [Diagram 2] 2 illustrates a unit cell of the secondary battery assembly of FIG. [Diagram 3] 3 illustrates a cathode structure for the unit cell of FIG. 2 of an exemplary embodiment. [Figure 4] Draw the anode structure for the unit cell in Figure 2. [Diagram 5] 1 illustrates a perspective view of an exemplary embodiment of a cushioning system; [Figure 6] Draw an exploded view of the cushioning system of Figure 5. [Figure 7] 1 depicts a perspective view of an exemplary embodiment auxiliary pole; [Figure 8] Draw an exploded view of the auxiliary pole in Figure 7. [Figure 9] 8 is a perspective view of the auxiliary pole of FIG. 7 at one stage in the assembly process of the auxiliary pole of FIG. 7. [Figure 10] 8 is a perspective view of the auxiliary pole of FIG. 7 at another stage in the assembly process of the auxiliary pole of FIG. 7. [Figure 11] 8 is a perspective view of the auxiliary pole of FIG. 7 at yet another stage in the assembly process of adding an extending tab to the auxiliary pole of FIG. 7. [Figure 12] 6 is a perspective view of the cushioning system of FIG. 5 at one stage in the assembly process of the cushioning system. [Figure 13] 6 is a perspective view of the cushioning system of FIG. 5 at one stage in the assembly process of the cushioning system. [Figure 14] 6 is a perspective view of the cushioning system of FIG. 5 at one stage in the assembly process of the cushioning system. [Figure 15] FIG. 15 is a cross-sectional view of a portion of the cushioning system of FIG. [Figure 16] 7A-7C are perspective views of the cushioning system of FIGS. 5-6 at different stages in an assembly process of the cushioning system. [Figure 17] FIG. 6 is a perspective view of the buffering system of FIG. 5 after performing a buffering process on the secondary battery. [Figure 18] 1 is a flowchart of a method for pre-lithiating a secondary battery with carrier ions using an auxiliary electrode of an exemplary embodiment. [Figure 19] 19 is a flowchart depicting further details of the method of FIG. 18. [Figure 20] 19 is a flowchart depicting further details of the method of FIG. 18. [Figure 21] 19 is a flowchart depicting further details of the method of FIG. 18. [Figure 22] FIG. 1 is a block diagram of an exemplary cell formation system. [Diagram 23] FIG. 23 is a diagram of an exemplary battery tray for the cell formation system of FIG. [Figure 24] FIG. 23 is a diagram of an exemplary forming base tray for the cell forming system of FIG. 22. [Figure 26]25 is a side view of the battery tray of FIG. 23 positioned to be attached to the forming base of FIG. 24 to form a forming assembly. [Figure 27] 25 is a partial view of the battery tray of FIG. 23 positioned on the forming base of FIG. 24 with the assembly connectors aligned. [Figure 28] 25 is a partial view of the battery tray of FIG. 23 lowered onto the forming base of FIG. 24. [Figure 29] 25 is a partial view of the battery tray of FIG. 23 lowered onto the forming base of FIG. 24 with the assembly connector engaged. [Diagram 30] FIG. 1 is a block diagram of an exemplary cell formation system for a lithium-based secondary battery. [Diagram 31] FIG. 31 is a block diagram of an exemplary cell forming cluster for use in the cell forming system of FIG. 30. [Diagram 32] FIG. 32 is a block diagram of an exemplary pre-lithiation module for use in the cell formation cluster of FIG. [Diagram 33] FIG. 33 is a simplified circuit diagram of an exemplary embodiment of a switched-capacitor circuit for use in the pre-lithiation module of FIG. [Figure 34A] 34 is a graph of a series of PFM control pulses applied to the switches of the switched capacitor circuit of FIG. 33 as a function of time. [Figure 34B] 34B is a graph of the resulting current through the auxiliary electrode in response to the control pulse of FIG. 34A as a function of time. [Diagram 35] FIG. 33 is a circuit diagram of an exemplary embodiment of a switched-capacitor circuit for use in the pre-lithiation module of FIG. [Figure 36A] 1 is a graph of a buffer current for use as part of an exemplary pre-lithiation profile. [Figure 36B] 1 is a graph of pulse duration for an exemplary prelithiation profile. [Figure 36C] 1 is a graph of the number of pulses for an exemplary pre-lithiation profile. [Figure 37A] FIG. 36C is a graph of the cathode-anode voltage and the cathode-auxiliary electrode voltage as a function of time when prelithiating using the prelithiation profiles of FIGS. 36A-36C. [Figure 37B] FIG. 36C is a graph of buffer current as a function of time when prelithiating using the prelithiation profiles of FIGS. 36A-36C. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] definition As used herein, "A," "an," and "the" (i.e., singular) refer to plural referents unless the context clearly dictates otherwise. For example, in one instance, reference to "an electrode" includes both a single electrode and a plurality of similar electrodes.

[0012] As used herein, "about" and "approximately" refer to plus or minus 10%, 5%, or 1% of the stated value. For example, in one example, about 250 micrometers (μm) includes 225 μm to 275 μm. As a further example, in one example, about 1,000 μm includes 900 μm to 1,100 μm. Unless otherwise indicated, all numbers expressing quantities (e.g., measurements, etc.) and the like used in the specification and claims should be understood in all instances as being modified by the term "about". Accordingly, unless otherwise indicated to the contrary, the numerical parameters set forth in the following specification and the appended claims are approximations. Each numerical parameter should be construed, at least in light of the number of reported significant digits and by applying ordinary rounding techniques.

[0013] "Anode" as used herein in the context of a secondary battery refers to the negative electrode in the secondary battery.

[0014] As used herein, "anode material" or "anode active" means a material suitable for use as the negative electrode of a secondary battery.

[0015] "Cathode" as used herein in the context of a secondary battery refers to the positive electrode in the secondary battery.

[0016] As used herein, "cathode material" or "cathode active" means a material suitable for use as the positive electrode of a secondary battery.

[0017] "Conversion chemically active material" or "conversion chemistry" refers to a material that undergoes a chemical reaction during the charge and discharge cycle of a secondary battery.

[0018] As used herein, "counter electrode" may refer to either the negative or positive electrode (anode or cathode) of a secondary battery, unless the context clearly indicates otherwise.

[0019] As used herein, "counter electrode current collector" may refer to the negative or positive (anode or cathode) current collector opposite the negative electrode current connector of a secondary battery, unless the context clearly indicates otherwise.

[0020] As used herein in the context of cycling a secondary battery between a charging state and a discharging state, "cycling" refers to charging and / or discharging the battery to move the battery in a cycle from a first state, either a charging state or a discharging state, to a second state that is the opposite of the first state (i.e., a charging state if the first state was discharged, or a discharging state if the first state was charged), and then returning the battery to the first state to complete the cycle. For example, a single cycle of a secondary battery between a charging state and a discharging state may include charging the battery from a discharging state to a charging state, as in a charging cycle, and then discharging to a discharging state to complete the cycle. A single cycle may also include discharging the battery from a charging state to a discharging state, as in a discharging cycle, and then charging to a charging state to complete the cycle.

[0021] As used herein, "electrochemically active material" means an anode active material or a cathode active material.

[0022] As used herein, "electrode" may refer to either the negative or positive electrode (anode or cathode) of a secondary battery, unless the context clearly indicates otherwise.

[0023] As used herein, "secondary battery current collector" may refer to either the negative or positive (anode or cathode) current collector of an electrode, unless the context clearly indicates otherwise.

[0024] As used herein, "electrode material" may refer to either an anode material or a cathode material, unless the context clearly indicates otherwise.

[0025] As used herein, "electrode structure" may refer to an anode structure (e.g., anode structure) or a cathode structure (e.g., cathode structure) adapted for use in a battery, unless the context clearly indicates otherwise.

[0026] "Capacity" or "C", as used herein, unless the context clearly indicates otherwise, refers to the amount of charge that a battery (or a subportion of a battery including one or more pairs of electrode and counter electrode structures forming a bilayer) can deliver at a given voltage.

[0027] "Electrolyte," as used herein, unless the context clearly indicates otherwise, refers to a non-metallic liquid, gel, or solid material adapted for use in a battery in which electrical current is carried by the movement of ions.

[0028] As used herein in the context of the condition of a secondary battery, "state of charge" refers to a state in which a secondary battery is charged to at least 75% of its rated capacity, unless the context clearly indicates otherwise. For example, a battery may be charged to at least 80% of its rated capacity, at least 90% of its rated capacity, or even at least 95% of its rated capacity, such as 100% of its rated capacity.

[0029] "Discharge capacity," as used herein with respect to the negative electrode, means the amount of carrier ions available for extraction from the negative electrode and insertion into the positive electrode during a discharge operation of the battery between a given set of cell end-of-charge and cell end-of-discharge voltage limits, unless the context clearly indicates otherwise.

[0030] A "discharged state," as used herein in the context of the state of a secondary battery, refers to a state in which a secondary battery is discharged to less than 25% of its specified capacity, unless the context clearly indicates otherwise. For example, a battery may be discharged to less than 20% of its rated capacity, such as less than 10% of its rated capacity, or even less than 5% of its rated capacity, such as 0% of its rated capacity.

[0031] "Reversible Coulombic capacity," as used herein with reference to an electrode (i.e., positive, negative, or auxiliary electrode), means the total capacity of the electrode for carrier ions available for reversible exchange with the counter electrode.

[0032] As used herein, the terms "longitudinal axis", "lateral axis", and "vertical axis" refer to axes that are perpendicular to one another (i.e., each is perpendicular to the other). For example, the terms "longitudinal axis", "lateral axis", and "vertical axis" used herein are similar to a Cartesian coordinate system used to define three-dimensional aspects or orientations. As such, the description of the elements of the subject matter disclosed herein is not limited to the particular axis(es) used to describe the three-dimensional orientation of the elements. Alternatively stated, the axes may be interchangeable when referring to three-dimensional aspects of the subject matter disclosed herein.

[0033] As used herein, "composite material" or "composite" refers to a material that includes two or more constituent materials, unless the context clearly indicates otherwise.

[0034] As used herein, "porosity" or "porosity" or "void volume fraction" refers to a measurement of void (i.e., empty) space in a material and is the fraction of the volume of voids relative to the total volume of the material as a percentage from 0 to 1, or 0% to 100%.

[0035] "Polymer," as used herein, unless the context clearly indicates otherwise, may refer to a substance or material composed of repeating macromolecular subunits.

[0036] As used herein, unless the context clearly indicates otherwise, "microstructure" may refer to the structure of the surface of a material as revealed by an optical microscope at a magnification of greater than about 25 times.

[0037] As used herein, unless the context clearly indicates otherwise, "microporous" may refer to a material that contains pores having diameters of less than about 2 nanometers.

[0038] As used herein, "macroporous" may refer to materials that contain pores having diameters greater than about 50 nanometers, unless the context clearly indicates otherwise.

[0039] As used herein, "nanoscale" or "nanoscopic scale" can refer to structures having length scales ranging from about 1 nanometer to about 100 nanometers.

[0040] As used herein, the terms “pre-lithiation” or “pre-lithiating” may refer to the addition of lithium to the active lithium content of a lithium-based secondary battery as part of the formation process prior to operation of the battery to compensate for the loss of active lithium.

[0041] The embodiments of the present disclosure provide a distributed formation process in which modern electronic devices and distributed embedded network strategies are adopted. Thus, instead of a centralized system that requires a dedicated connection to every battery undergoing a formation process and controls the formation process of hundreds or thousands of batteries, the formation process in the exemplary embodiments of the present disclosure is distributed among smaller clusters, each of which directly handles the formation process of the battery to which it is connected. These embodiments can simplify the construction of the formation system by requiring a less powerful central controller and less interconnection wiring, while allowing the formation processing system to be more easily scaled and physically distributed to desired locations.

[0042] Some embodiments of the present disclosure may provide advantages such as mitigation or amelioration of poor ICE associated with silicon-based anodes in secondary batteries utilizing an auxiliary anode electrochemically coupled with the secondary battery to provide additional carrier ions during and / or after initial battery formation. The use of the auxiliary anode mitigates the initial loss of carrier ions in the secondary battery during initial formation, thereby providing the technical advantage of, for example, increasing the capacity of the secondary battery after formation. Furthermore, the introduction of additional carrier ions after battery formation mitigates the cycle-based loss of carrier ions typically lost through secondary reactions, thereby providing the technical advantage of reducing capacity loss per cycle in the secondary battery. Still further, the introduction of additional carrier ions after battery formation improves the cycle performance of the secondary battery by maintaining the anode of the secondary battery at a lower potential voltage upon discharge since the anode contains additional carrier ions. In some embodiments, the auxiliary anode is removed from the secondary battery after formation, thereby providing the technical advantage of increasing the energy density of the battery.

[0043] Figure 1 is a perspective view of an exemplary embodiment of a secondary battery 100, and Figure 2 illustrates a unit cell 200 for the secondary battery 100. The secondary battery 100 of Figure 1 has an exposed portion that shows a portion of the internal structure of the secondary battery, as described further below.

[0044] As illustrated in FIG. 1, the secondary battery 100 includes a plurality of adjacent subunits 102. Each of the electrode subunits 102 has dimensions of an X-axis, a Y-axis, and a Z-axis, respectively. The X-axis, the Y-axis, and the Z-axis are each perpendicular to each other, similar to a Cartesian coordinate system. As used herein, the dimension of each electrode subunit 102 in the Z-axis may be referred to as the "height", the dimension in the X-axis may be referred to as the "length", and the dimension in the Y-axis may be referred to as the "width". The electrode subunits 102 may be combined into one or more unit cells 200 (see FIG. 2). Each of the unit cells 200 includes at least one anode active material layer 104 and at least one cathode active material layer 106. The anode active material layer 104 and the cathode active material layer 106 are electrically insulated from each other by a separator layer 108. It should be understood that in preferred embodiments of the present disclosure, any number of electrode subunits 102 may be used in the secondary battery 100, such as 1 to 200 or more electrode subunits 102.

[0045] Referring to FIG. 1, the secondary battery 100 includes a first bus bar 110 and a second bus bar 112, which are in electrical contact with the anode active material layer 104 and the cathode active material layer 106 of each of the electrode subunits 102, respectively, via electrode tabs 114. The electrode tabs 114 are only visible on a first side 120 of the secondary battery 100 in FIG. 1, but a different set of electrode tabs 114 is present on a second side 121 of the secondary battery. The electrode tabs 114 on the first side 120 of the secondary battery 100 are electrically coupled to the first bus bar 110, which may be referred to as an anode bus bar. The electrode tabs 114 on the second side 121 of the secondary battery 100 (not visible in FIG. 1) are electrically coupled to the second bus bar 112, which may be referred to as a cathode bus bar. In this embodiment, the first bus bar 110 is electrically coupled to a first electrical terminal 124 of the secondary battery 100, which is electrically conductive. If the first busbar 110 comprises a positive busbar for the secondary battery, the first electrical terminal 124 comprises a negative terminal for the secondary battery 100. Further, in this embodiment, the second busbar 112 is electrically coupled to a second electrical terminal 125 of the secondary battery 100, which is electrically conductive. If the second busbar 112 comprises a negative busbar for the secondary battery, the second electrical terminal 125 comprises a positive terminal for the secondary battery 100.

[0046] In one embodiment, a casing 116, which may be referred to as a constraint, may be applied over one or both of the XY surfaces of the secondary battery 100. In the embodiment shown in Figure 1, the casing 116 includes a number of perforations 118 to facilitate electrolyte distribution or flow once the secondary battery 100 is fully assembled. In one embodiment, the casing 116 includes stainless steel, such as SS301, SS316, 440C, or 440C hard. In other embodiments, the casing 116 is made of aluminum (e.g., aluminum 7075-T6, hard H18, etc.), titanium (e.g., 6Al-4V), beryllium, beryllium copper (hard), copper (O2 free, hard), nickel, other metals or metal alloys, composites, polymers, ceramics (e.g., alumina (e.g., sintered or Coorstek AD96), zirconia (e.g., Coorstek YZTP), yttria stabilized zirconia (e.g., ENrG E-Strate®)), glass, tempered glass, polyetheretherketone (PEEK) (e.g., Aptiv 1102), PEEK with carbon (e.g., Victrex 90HMF40 or Xycomp 1000-04), polyphenylene sulfide (PPS) with carbon (e.g., Tepex Dynalite 207), 30% Polyetheretherketone (PEEK) glass (e.g., Victrex 90HMF40 or Xycomp 1000-04), Polyimide (e.g., Kapton®), E Glass Std Fabric / Epoxy, 0°, E Glass UD / Epoxy, 0°, Kevlar Std Fabric / Epoxy, 0°, Kevlar UD / Epoxy, 0°, Carbon Std Fabric / Epoxy, 0°, Carbon UD / Epoxy, 0°, Toyobo Zylon® HM Fiber / Epoxy, Kevlar 49 Aramid Fiber, S Glass Fibers, Carbon Fibers, Vectran UM LCP Fibers, Dyneema, Zylon, or other suitable materials.

[0047] In some embodiments, the casing 116 comprises a sheet having a thickness ranging from about 10 to about 100 micrometers. In one embodiment, the casing 116 comprises a stainless steel sheet (e.g., SS316) having a thickness of about 30 μm. In another embodiment, the casing 116 comprises an aluminum sheet (e.g., 7075-T6) having a thickness of about 40 μm. In another embodiment, the casing 116 comprises a zirconia sheet (e.g., Coorstek YZTP) having a thickness of about 30 μm. In another embodiment, the casing 116 comprises an E-glass UD / epoxy 0 degree sheet having a thickness of about 75 μm. In another embodiment, the casing 116 comprises 12 μm carbon fiber with a packing density of >50%.

[0048] In this embodiment, secondary battery 100 includes a first major surface 126 and a second major surface 127 opposite first major surface 126. Major surfaces 126, 127 of secondary battery 100 may be substantially planar in some embodiments.

[0049] Referring to FIG. 2, which shows the secondary battery 100 along the cut line DD in FIG. 1, individual layers of a unit cell 200, which may be the same or similar to the electrode subunit 102, are depicted. For each of the unit cells 200, in some embodiments, the separator layer 108 is an ion-permeable microporous polymeric material suitable for use as a separator in a secondary battery. In one embodiment, the separator layer 108 is coated with ceramic particles on one or both sides. In this embodiment, the unit cell 200 includes a positive electrode current collector 202 in the center, which may include or be electrically coupled to one of the tabs 114 on one of the sides 120, 121 of the secondary battery 100 (see FIG. 1). The unit cell 200 further includes, in a stacked formation, a positive electrode active material layer 104, a separator layer 108, a negative electrode active material layer 106, and a negative electrode current collector 204. The negative electrode current collector 204 may include or be electrically coupled to one of the tabs 114 on one of the sides 120 , 121 of the secondary battery 100 that is different from the positive electrode current collector 202 .

[0050] In an alternative embodiment, the arrangement of the cathode active material layer 106 and the anode active material layer 104 may be swapped such that the cathode active material layer is toward the center and the anode active material layer is distal to the cathode active material layer. In one embodiment, unit cell 200A includes, stacked in succession from left to right, an anode current collector 202, an anode active material layer 104, a separator layer 108, a cathode active material layer 106, and a cathode current collector 204. In an alternative embodiment, unit cell 200B includes, stacked in succession from left to right, a separator layer 108, a first layer of cathode active material layer 106, a cathode current collector 204, a second layer of cathode active material layer, a separator layer, a first layer of anode active material layer 104, an anode current collector 202, a second layer of anode active material layer, and a separator layer.

[0051] 2, the layered structure comprising the cathode active material layer 106 and the cathode current collector 204 may be referred to as a cathode structure 206, while the layered structure comprising the anode active material layer 104 and the anode current collector 202 may be referred to as an anode structure 207. Collectively, the collection of cathode structures 206 for the secondary battery 100 may be referred to as the positive electrode 208 of the secondary battery, and the collection of anode structures 207 for the secondary battery 100 (only one of the anode structures is shown in FIG. 2) may be referred to as the negative electrode 209 of the secondary battery.

[0052] A voltage difference V exists between adjacent cathode structures 206 and anode structures 207, the adjacent structures being considered bilayers in some embodiments. Each bilayer has a capacity C determined by the configuration and construction of the cathode structures 206 and anode structures 207. In this embodiment, each bilayer produces a voltage difference of about 4.35 volts. In other embodiments, each bilayer has a voltage difference of about 0.5 volts, about 1.0 volts, about 1.5 volts, about 2.0 volts, about 2.5 volts, about 3.0 volts, about 3.5 volts, about 4.0 volts, 4.5 volts, about 5.0 volts, 4-5 volts, or any other suitable voltage. During cycling between charge and discharge states, the voltage may vary, for example, between about 2.5 volts and about 4.35 volts. The capacity C of the bilayer in this embodiment is about 3.5 milliamp hours (mAh). In other embodiments, the capacity C of the bilayer is about 2 mAh, less than 5 mAh, or any other suitable capacity. In some embodiments, the capacity C of the bilayer can be up to about 10 mAh.

[0053] The cathode current collector 204 may include aluminum, nickel, cobalt, titanium, and tungsten, or alloys thereof, or any other material suitable for use as a cathode current collector layer. 3 For example, in one such embodiment, the cathode current collector 204 has a conductivity of at least about 10 4 By way of further example, in one such embodiment, the cathode current collector 204 has a conductivity of at least about 10 5The cathode current collector 204 has a conductivity of Siemens / cm. In general, the cathode current collector 204 may include a metal such as aluminum, carbon, chromium, gold, nickel, NiP, palladium, platinum, rhodium, ruthenium, alloys of silicon and nickel, titanium, or combinations thereof (see A.H. Whitehead and M. Schreiber, "Current collectors for positive electrodes of lithium-based batteries," Journal of the Electrochemical Society, 152(11)A2105-A2113 (2005)). By way of further example, in one embodiment, the cathode current collector 204 includes gold or an alloy thereof, such as gold silicide. By way of further example, in one embodiment, the cathode current collector 204 includes nickel or an alloy thereof, such as nickel silicide.

[0054] The cathode active material layer 106 can be an intercalation-type chemically active material, a conversion chemically active material, or a combination thereof.

[0055] Exemplary conversion chemical materials useful in the present disclosure include S (or the lithiated form LiS), LiF, Fe, Cu, Ni, FeF, FeO d F 3.2d , FeF3, CoF3, CoF2, CuF2, NiF2, and the like, where 0≦d≦0.5, and the like.

[0056] The exemplary cathode active material layer 106 may also include any of a wide range of intercalation-type cathode active materials. For example, in the case of a lithium-ion battery, the cathode active material may include a cathode active material selected from transition metal oxides, transition metal sulfides, transition metal nitrides, lithium transition metal oxides, and lithium transition metal sulfides, with lithium transition metal nitrides being selectively used. The transition metal elements of these transition metal oxides, transition metal sulfides, and transition metal nitrides may include metal elements having a d-shell or an f-shell. Specific examples of such metal elements may include Sc, Y, lanthanides, actinides, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Tc, Re, Fe, Ru, Os, Co, Rh, Ir, Ni, Pb, Pt, Cu, Ag, and Au. Additional cathode active materials include LiCoO2, LiNi 0.5 Mn 1.5 O4, Li(Ni x Co y Al z )O2, LiFePO4, Li2MnO4, V2O5, molybdenum oxysulfide, phosphates, silicates, vanadates, sulfur, sulfur compounds, oxygen (air), Li(Ni x Mn y Co z ) O2, and combinations thereof.

[0057] Generally, the cathode active material layer 106 has a thickness of at least about 20 μm. For example, in one embodiment, the cathode active material layer 106 has a thickness of at least about 40 μm. By way of further example, in one such embodiment, the cathode active material layer 106 has a thickness of at least about 60 μm. By way of further example, in one such embodiment, the cathode active material layer 106 has a thickness of at least about 100 μm. Typically, the cathode active material layer 106 has a thickness of less than about 90 μm or less than about 70 μm.

[0058] FIG. 3 illustrates the cathode structures 206 of FIG. 2. Each cathode structure 206 has a longitudinal axis (A CE ) measured along the length (L CE ) and width (W CE ) and length L CE and width WCE The height (H CE ) and.

[0059] The total length L of the cathode structure 206 CE will vary depending on the secondary battery 100 and its intended use. In general, however, each cathode structure 206 typically has a length L in the range of about 5 millimeters (mm) to about 500 mm. CE For example, in one such embodiment, each cathode structure 206 has a length L of about 10 mm to about 250 mm. CE By way of further example, in one such embodiment, each cathode structure 206 has a length L of about 25 mm to about 100 mm. CE According to one embodiment, the cathode structure 206 includes one or more first electrode members having a first length and one or more second electrode members having a second length different from the first length. In yet another embodiment, the different lengths of the one or more first electrode members and the one or more second electrode members may be selected to conform to a predetermined shape of the electrode assembly, such as an electrode assembly shape having different lengths along one or more of the longitudinal and / or lateral axes, and / or to provide predetermined performance characteristics of the secondary battery 100.

[0060] Width W of cathode structure 206 CE W also varies depending on the secondary battery 100 and its intended use. In general, however, the cathode structure 206 typically has a width W in the range of about 0.01 mm to 2.5 mm. CE For example, in one embodiment, each cathode structure 206 has a width W CE By way of further example, in one embodiment, the width W of each cathode structure 206 ranges from about 0.025 mm to about 2 mm. CEis in the range of about 0.05 mm to about 1 mm. According to one embodiment, the cathode structure 206 includes one or more first electrode members having a first width and one or more second electrode members having a second width different from the first width. In yet another embodiment, the different widths of the one or more first electrode members and the one or more second electrode members may be selected to conform to a predetermined shape of the secondary battery 100, such as an assembly having different widths along one or more of the longitudinal and / or lateral axes, and / or to provide predetermined performance characteristics of the secondary battery.

[0061] Height H of cathode structure 206 CE will vary depending on the secondary battery 100 and its intended use. In general, however, the cathode structure 206 typically has a height H in the range of about 0.05 mm to about 25 mm. CE For example, in one embodiment, each cathode structure 206 has a height H CE By way of further example, in one embodiment, the height H of each cathode structure 206 ranges from about 0.05 mm to about 5 mm. CE is in the range of about 0.1 mm to about 1 mm. According to one embodiment, the cathode structure 206 includes one or more first cathode members having a first height and one or more second cathode members having a second height different from the first height. In yet another embodiment, the different heights of the one or more first cathode members and the one or more second cathode members may be selected to conform to a predetermined shape of the secondary battery 100, such as a shape having different heights along one or more of the longitudinal and / or lateral axes, and / or to provide predetermined performance characteristics of the secondary battery.

[0062] Generally, each cathode structure 206 has a width W CE and its height H CE Length L, substantially larger than CE For example, in one embodiment, for each cathode structure 206, L CE and W CE and H CE and each of the L CE and W CEand L are at least 5:1, respectively. CE and H CE and W are each at least 5:1. CE and H CE L for each CE is at least 10:1 for each cathode structure 206. By way of further example, in one embodiment, W CE and H CE L for each CE is at least 15:1 for each cathode structure 206. By way of further example, in one embodiment, W CE and H CE L for each CE is at least 20:1 for each cathode structure 206.

[0063] In one embodiment, the width W of the cathode structure 206 CE Height H CE and H are each at least 0.4:1. CE Against W CE is at least 2:1, respectively, for each cathode structure 206. By way of further example, in one embodiment, H CE Against W CE is at least 10:1, respectively, for each cathode structure 206. By way of further example, in one embodiment, H CE Against W CE The ratio of H is at least 20:1 for each cathode structure 206, respectively. CE Against W CE The ratio of H is generally less than 1,000:1, respectively, for each cathode structure 206. For example, in one embodiment, CE Against W CE is less than 500:1, respectively, for each cathode structure 206. By way of further example, in one embodiment, H CE W CE and H are each less than 100:1. CE W CEand H are each less than 10:1. CE Against W CE is in the range of about 2:1 to about 100:1 for each cathode structure 206, respectively.

[0064] Anode structure and materials 2, the anode current collector 202 in the unit cell 200 may comprise a conductive material such as copper, carbon, nickel, stainless steel, cobalt, titanium, and tungsten, and alloys thereof, or any other material suitable as an anode current collector layer. Generally, the anode current collector 202 has a thickness of at least about 10 3 For example, in one such embodiment, the anode current collector 202 has a conductivity of at least about 10 4 By way of further example, in one such embodiment, the anode current collector 202 has a conductivity of at least about 10 5 It has a conductivity in Siemens / cm.

[0065] Generally, the anode active material layer 104 in the unit cell 200 can be selected from the group consisting of: (a) silicon (Si), germanium (Ge), tin (Sn), lead (Pb), antimony (Sb), bismuth (Bi), zinc (Zn), aluminum (Al), titanium (Ti), nickel (Ni), cobalt (Co), and cadmium (Cd); (b) alloys or intermetallic compounds of Si, Ge, Sn, Pb, Sb, Bi, Zn, Al, Ti, Ni, Co, or Cd with other elements; (c) alloys or intermetallic compounds of Si, Ge, Sn, Pb, Sb, Bi, Zn , oxides, carbides, nitrides, sulfides, phosphides, selenides, and tellurides of Al, Ti, Fe, Ni, Co, V, or Cd, and mixtures, composites, or lithium-containing composites thereof; (d) salts and hydroxides of Sn; (e) lithium titanate, lithium manganate, lithium aluminate, lithium-containing titanium oxides, lithium transition metal oxides, ZnCo2O4; (f) particles of graphite and carbon; (g) lithium metal; and (h) combinations thereof.

[0066] Exemplary anode active material layer 104 includes graphite and soft or hard carbon, or carbon materials such as graphene (e.g., single-walled or multi-walled carbon nanotubes), or any of a range of metals, metalloids, alloys, oxides, nitrides, and compounds that can intercalate or alloy with lithium. Specific examples of metals or metalloids that can comprise the anode material include graphite, tin, lead, magnesium, aluminum, boron, gallium, silicon, Si / C composites, Si / graphite blends, silicon oxide (SiOx), porous Si, intermetallic Si alloys, indium, zirconium, germanium, bismuth, cadmium, antimony, silver, zinc, arsenic, hafnium, yttrium, lithium, sodium, graphite, carbon, lithium titanate, palladium, and mixtures thereof. In one exemplary embodiment, the anode active material includes aluminum, tin, or silicon, or oxides thereof, nitrides thereof, fluorides thereof, or other alloys thereof. In another exemplary embodiment, the anode active material layer 104 includes silicon or an alloy or oxide thereof.

[0067] In one embodiment, the anode active material layer 104 is microstructured to provide a significant void volume fraction to accommodate volumetric expansion and contraction as lithium ions (or other carrier ions) are incorporated into or exit the anode active material layer during charging and discharging processes of the secondary battery 100. In general, the void volume fraction of the (each of) the anode active material layer 104 is at least 0.1. Typically, however, the void volume fraction of the (each of) the anode active material layer 104 is 0.8 or less. For example, in one embodiment, the void volume fraction of the (each of) the anode active material layer 104 is about 0.15 to about 0.75. By way of further example, in one embodiment, the void volume fraction of the (each of) the anode active material layer 104 is about 0.2 to about 0.7. By way of further example, in one embodiment, the void volume fraction of the (each of) the anode active material layer 104 is about 0.25 to about 0.6.

[0068] Depending on the composition of the microstructured anode active material layers 104 and their method of formation, the microstructured anode active material layers may include macroporous, microporous, or mesoporous material layers, or combinations thereof, such as a combination of mesoporous and macroporous. Microporous materials are typically characterized by pore dimensions less than 10 nanometers (nm), wall dimensions less than 10 nm, pore depths between 1 μm and 50 μm, and pore morphologies generally characterized by a "spongy" irregular appearance, non-smooth walls, and branched pores. Mesoporous materials are typically characterized by pore dimensions between 10 nm and 50 nm, wall dimensions between 10 nm and 50 nm, pore depths between 1 μm and 100 μm, and pore morphologies generally characterized by more or less well-defined branched or dendritic pores. Macroporous materials are typically characterized by pore dimensions greater than 50 nm, wall dimensions greater than 50 nm, pore depths between 1 μm and 500 μm, and pore morphologies that can be linear, branched, or dendritic, and smooth or rough-walled. In addition, the void volume can include open or closed porosity, or a combination thereof. In one embodiment, the void volume includes open porosity, i.e., the anode active material layer 104 includes porosity at the sides of the anode active material layer that has openings through which lithium ions (or other carrier ions) can enter or exit. For example, lithium ions can enter the anode active material layer 104 through the pore openings after leaving the cathode active material layer 106. In another embodiment, the void volume includes closed porosity, i.e., the anode active material layer 104 includes porosity that is enclosed. In general, open porosity can provide a larger interfacial surface area for carrier ions, while closed porosity tends to be less susceptible to SEI formation, each providing room for expansion of the anode active material layer 104 upon the ingress of carrier ions. Thus, in certain embodiments, it is preferred that the anode active material layer include a combination of open and closed porosity.

[0069] In one embodiment, the anode active material layer 104 comprises porous aluminum, tin, or silicon, or alloys, oxides, or nitrides thereof. The porous silicon layer may be formed, for example, by anodization, by etching (e.g., by depositing a precious metal such as gold, platinum, silver, or gold / palladium on the surface of single crystal silicon and etching the surface with a mixture of hydrofluoric acid and hydrogen peroxide), or by other methods known in the art, such as patterned chemical etching. In addition, the porous anode active material layer 104 generally has a porosity of at least about 0.1 but less than 0.8, and a thickness of about 1 μm to about 100 μm. For example, in one embodiment, the anode active material layer 104 comprises porous silicon, has a thickness of about 5 μm to about 100 μm, and has a porosity of about 0.15 to about 0.75. By way of further example, in one embodiment, the anode active material layer 104 comprises porous silicon, has a thickness of about 10 μm to about 80 μm, and has a porosity of about 0.15 to about 0.7. By way of further example, in one such embodiment, the anode active material layer 104 comprises porous silicon, has a thickness of about 20 μm to about 50 μm, and has a porosity of about 0.25 to about 0.6. By way of further example, in one such embodiment, the anode active material layer 104 comprises a porous silicon alloy (such as nickel silicide), has a thickness of about 5 μm to about 100 μm, and has a porosity of about 0.15 to about 0.75.

[0070] In another embodiment, the anode active material layer 104 comprises fibers of aluminum, tin, or silicon, or alloys thereof. The individual fibers may have a diameter (thickness dimension) of about 5 nm to about 10,000 nm, and a length that generally corresponds to the thickness of the anode active material layer. The silicon fibers (nanowires) may be formed by, for example, chemical vapor deposition or other techniques known in the art, such as vapor-liquid-solid (VLS) growth and solid-liquid-solid (SLS) growth. In addition, the anode active material layer 104 generally has a porosity of at least about 0.1 but less than 0.8, and a thickness of about 1 μm to about 200 μm. For example, in one embodiment, the anode active material layer 104 comprises silicon nanowires, has a thickness of about 5 μm to about 100 μm, and a porosity of about 0.15 to about 0.75. By way of further example, in one embodiment, anode active material layer 104 comprises silicon nanowires, has a thickness of about 10 μm to about 80 μm, and a porosity of about 0.15 to about 0.7. By way of further example, in one such embodiment, anode active material layer 104 comprises silicon nanowires, has a thickness of about 20 μm to about 50 μm, and a porosity of about 0.25 to about 0.6. By way of further example, in one such embodiment, anode active material layer 104 comprises silicon alloy (such as nickel silicide) nanowires, has a thickness of about 5 μm to about 100 μm, and a porosity of about 0.15 to about 0.75.

[0071] In yet another embodiment, the anode active material layer 104 is coated with a particulate lithium material selected from the group consisting of stabilized lithium metal particles, such as lithium carbonate stabilized lithium metal powder, lithium silicate stabilized lithium metal powder, or other sources of stabilized lithium metal powder or ink. The particulate lithium material is coated with a concentration of about 0.05 mg / cm. 2 ~5mg / cm 2 , for example, about 0.1 mg / cm 2 ~4mg / cm 2 , or even about 0.5 mg / cm 2 ~3mg / cm 2 The lithium particulate material may be applied onto the anode active material layer 104 by spraying, packing, or otherwise disposing on the anode active material layer at a loading of 0.1 to 0.5 μm. 50The average particle size (D) can be from 5 μm to 200 μm, for example, from about 10 μm to 100 μm, from 20 μm to 80 μm, or even from about 30 μm to 50 μm. 50 ) can be defined as the particle size corresponding to 50% on the cumulative volume-based particle size distribution curve. 50 ) can be measured, for example, using laser diffraction methods.

[0072] In one embodiment, the anode current collector 202 has a conductivity that is substantially greater than the conductivity of its associated anode active material layer 104. For example, in one embodiment, the ratio of the conductivity of the anode current collector 202 to the conductivity of the anode active material layer 104 is at least 100:1 when there is an applied current to store energy in the secondary battery 100 or an applied load to discharge the secondary battery. By way of further example, in some embodiments, the ratio of the conductivity of the anode current collector 202 to the conductivity of the anode active material layer 104 is at least 500:1 when there is an applied current to store energy in the secondary battery 100 or an applied load to discharge the secondary battery. By way of further example, in some embodiments, the ratio of the conductivity of the anode current collector 202 to the conductivity of the anode active material layer 104 is at least 1000:1 when there is an applied current to store energy in the secondary battery 100 or an applied load to discharge the secondary battery. By way of further example, in some embodiments, the ratio of the electrical conductivity of the anode current collector 202 to the electrical conductivity of the anode active material layer 104 is at least 5000:1 when there is an applied current to store energy in the secondary battery 100 or an applied load to discharge the secondary battery. By way of further example, in some embodiments, the ratio of the electrical conductivity of the anode current collector 202 to the electrical conductivity of the anode active material layer 104 is at least 10000:1 when there is an applied current to store energy in the secondary battery 100 or an applied load to discharge the secondary battery.

[0073] FIG. 4 illustrates an exemplary embodiment of the anode structure 207 of FIG. 2. Each anode structure 207 of FIG. 4 is aligned along the longitudinal axis (A E ) measured along the length (LE ) and width (W E ) and length L E and width W E The height (H E ) and.

[0074] Length L of anode structure 207 E will vary depending on the secondary battery 100 and its intended use. In general, however, the anode structure 207 typically has a length L in the range of about 5 millimeters (mm) to about 500 mm. E For example, in one such embodiment, the anode structure 207 has a length L of about 10 mm to about 250 mm. E By way of further example, in one such embodiment, the anode structure 207 has a length L of about 25 mm to about 100 mm. E According to one embodiment, the anode structure 207 includes one or more first electrode members having a first length and one or more second electrode members having a second length different from the first length. In yet another embodiment, the different lengths of the one or more first electrode members and the one or more second electrode members may be selected to conform to a predetermined shape of the secondary battery 100, such as a shape having different lengths along one or more of the longitudinal and / or lateral axes, and / or to provide predetermined performance characteristics of the secondary battery 100.

[0075] Width W of anode structure 207 E W also varies depending on the secondary battery 100 and its intended use. In general, however, each anode structure 207 typically has a width W in the range of about 0.01 mm to 2.5 mm. E For example, in one embodiment, each anode structure 207 has a width W E By way of further example, in one embodiment, the width W of each anode structure 207 ranges from about 0.025 mm to about 2 mm. Eis in the range of about 0.05 mm to about 1 mm. According to one embodiment, the anode structure 207 includes one or more first electrode members having a first width and one or more second electrode members having a second width different from the first width. In yet another embodiment, the different widths of the one or more first electrode members and the one or more second electrode members may be selected to conform to a predetermined shape of the secondary battery 100, such as a shape having different widths along one or more of the longitudinal and / or lateral axes, and / or to provide predetermined performance characteristics of the secondary battery 100.

[0076] Height H of anode structure 207 E H also varies depending on the secondary battery 100 and its intended use. In general, however, the anode structure 207 typically has a height H in the range of about 0.05 mm to about 25 mm. E For example, in one embodiment, each anode structure 207 has a height H E By way of further example, in one embodiment, the height H of each anode structure 207 ranges from about 0.05 mm to about 5 mm. E is in the range of about 0.1 mm to about 1 mm. According to one embodiment, the anode structure 207 includes one or more first electrode members having a first height and one or more second electrode members having a second height different from the first height. In yet another embodiment, the different heights for the one or more first electrode members and the one or more second electrode members may be selected to conform to a predetermined shape of the secondary battery 100, such as a shape having different heights along one or more of the longitudinal and / or lateral axes, and / or to provide predetermined performance characteristics of the secondary battery.

[0077] Generally, the anode structure 207 has a width W E and its height H E A length L substantially larger than each of E For example, in one embodiment, for each anode structure 207, L E and W E and H E and each of the L E and W Eand L are at least 5:1, respectively. E and H E and W are each at least 5:1. E and H E L for each E is at least 10:1. By way of further example, in one embodiment, W E and H E L for each E is at least 15:1. By way of further example, in one embodiment, W E and H E L for each E is at least 20:1 for each anode structure 207.

[0078] In one embodiment, the width W of the anode structure 207 E Height H E The ratio of H to H is at least 0.4:1, respectively. For example, in one embodiment, E Against W E is at least 2:1, respectively, for each anode structure 207. By way of further example, in one embodiment, H E W E and H are each at least 10:1. E W E The ratio of H to H is at least 20:1, respectively. E W E and H are generally less than 1,000:1, respectively. For example, in one embodiment, E W E and H are each less than 500:1. E W E and H are each less than 100:1. E W E and H are each less than 10:1. E W Eto ranges from about 2:1 to about 100:1 for each anode structure 207, respectively.

[0079] Separator structure, separator material, and electrolyte Referring again to FIG. 2, separator layer(s) 108 separate the cathode structure 206 from the anode structure 207. The separator layer 108 is made of an electrically insulating but ionically permeable separator material. The separator layer 108 is adapted to electrically insulate each member of the plurality of cathode structures 206 from each member of the plurality of anode structures 207. Each separator layer 108 will typically comprise a microporous separator material that can be permeated with a non-aqueous electrolyte; for example, in one embodiment, the microporous separator material comprises pores having diameters of at least 50 angstroms (Å), more typically in the range of about 2,500 Å, and a porosity in the range of about 25% to about 75%, more typically in the range of about 35% to 55%.

[0080] Generally, the separator layers 108 each have a thickness of at least about 4 μm. For example, in one embodiment, the separator layers 108 have a thickness of at least about 8 μm. By way of further example, in one such embodiment, the separator layers 108 have a thickness of at least about 12 μm. By way of further example, in one such embodiment, the separator layers 108 have a thickness of at least about 15 μm. In some embodiments, the separator layers 108 have a thickness of up to 25 μm, up to 50 μm, or any other suitable thickness. Typically, however, the separator layers 108 have a thickness of less than about 12 μm or less than about 10 μm.

[0081] In general, the material of the separator layer 108 can be selected from a wide range of materials capable of conducting carrier ions between the anode active material layer 104 and the cathode active material layer 106 of the unit cell 200. For example, the separator layer 108 can include a microporous separator material capable of being permeated with a liquid non-aqueous electrolyte. Alternatively, the separator layer 108 can include a gel or solid electrolyte capable of conducting carrier ions between the anode active material layer 104 and the cathode active material layer 106 of the unit cell 200.

[0082] In one embodiment, the separator layer 108 may include a polymer-based electrolyte. Exemplary polymer electrolytes include PEO-based polymer electrolytes, polymer-ceramic composite electrolytes, polymer-ceramic composite electrolytes, and polymer-ceramic composite electrolytes.

[0083] In another embodiment, the separator layer 108 may include an oxide-based electrolyte. An exemplary oxide-based electrolyte is lithium lanthanum titanate (Li 0.34 La 0.56 TiO3), Al-doped lanthanum zirconate lithium (Li 6.24 La3Zr2Al 0.24 O 11.98 ), Ta-doped lithium lanthanum zirconate (Li 6.4 La3Zr 1.4 Ta 0.6 O 12 ), and lithium aluminum titanium phosphate (Li 1.4 Al 0.4 Ti 1.6 (PO4)3).

[0084] In another embodiment, the separator layer 108 may include a solid electrolyte. An exemplary solid electrolyte is lithium tin sulfide (Li 10 SnP2S 12 ), lithium phosphorus sulfide (β-Li3PS4), and lithium phosphorus sulfide iodide (Li6PS5Cl 0.9 I 0.1 ) and other sulfide-based electrolytes.

[0085] In some embodiments, the separator layer 108 may include a solid lithium-ion conducting ceramic, such as a lithium-filled garnet.

[0086] In one embodiment, the separator layer 108 comprises a microporous separator material including a particulate material and a binder, the microporous separator material having a porosity of at least about 20% by volume. The pores of the microporous separator material have a diameter of at least 50 Å, typically in the range of about 250 Å to about 2500 Å. The microporous separator material typically has a porosity of less than about 75%. In one embodiment, the microporous separator material has a porosity of at least about 25% by volume. In one embodiment, the microporous separator material has a porosity of about 35 to 55%.

[0087] Binders for microporous separator materials can be selected from a wide range of inorganic or polymeric materials. For example, in one embodiment, the binder is an organic material selected from the group consisting of silicates, phosphates, aluminates, aluminosilicates, and hydroxides such as magnesium hydroxide, calcium hydroxide, etc. For example, in one embodiment, the binder is a fluoropolymer derived from monomers containing vinylidene fluoride, hexafluoropropylene, tetrafluoropropene, etc. In another embodiment, the binder is a polyolefin such as polyethylene, polypropylene, or polybutene having any of a variety of molecular weight and density ranges. In another embodiment, the binder is selected from the group consisting of ethylene-diene-propene terpolymer, polystyrene, polymethyl methacrylate, polyethylene glycol, polyvinyl acetate, polyvinyl butyral, polyacetal, and polyethylene glycol diacrylate. In another embodiment, the binder is selected from the group consisting of methyl cellulose, carboxymethyl cellulose, styrene rubber, butadiene rubber, styrene butadiene rubber, isoprene rubber, polyacrylamide, polyvinyl ether, polyacrylic acid, polymethacrylic acid, and polyethylene oxide. In another embodiment, the binder is selected from the group consisting of acrylates, styrenes, epoxies, and silicones, hi another embodiment, the binder is a copolymer or blend of two or more of the foregoing polymers.

[0088] The particulate material included in the microporous separator material may also be selected from a wide range of materials. Generally, such materials have relatively low electronic and ionic conductivity at operating temperatures and do not corrode under the operating voltages of the battery electrodes or current collectors that contact the microporous separator material. For example, in one embodiment, the particulate material is in the range of 1×10 -4 By way of further example, in one embodiment, the particulate material has a conductivity for carrier ions (e.g., lithium) of less than 1×10 -5 By way of further example, in one embodiment, the particulate material has a carrier ion conductivity of less than 1×10 -6The conductive material has a carrier ion conductivity of less than 10 ... In one embodiment, the particulate material has an average particle size of about 20 nm to 2 μm, more typically 200 nm to 1.5 μm, In one embodiment, the particulate material has an average particle size of about 500 nm to 1 μm.

[0089] In alternative embodiments, the particulate materials comprised by the microporous separator material may be bound by techniques such as sintering, bonding, curing, etc., while maintaining a desired porosity for electrolyte infiltration to provide ionic conductivity for the functioning of the battery.

[0090] In secondary battery 100 (see FIG. 1), the microporous separator material of separator layer 108 is infiltrated with a non-aqueous electrolyte suitable for use as a secondary battery electrolyte. Typically, the non-aqueous electrolyte comprises a lithium salt and / or mixture of salts dissolved in an organic solvent and / or solvent mixture. Exemplary lithium salts include inorganic lithium such as LiClO4, LiBF4, LiPF6, LiAsF6, LiCl, and LiBr, as well as inorganic lithium salts such as LiB(C6H5)4, LiN(SO2CF3)2, LiN(SO2CF3)3, LiNSO2CF3, LiNSO2CF5, LiNSO2C4F9, LiNSO2C5F 11 , LiNSO2C6F 13 , and LiNSO2C7F 15Examples of organic lithium salts include organic lithium salts such as cyclic esters, chain esters, cyclic ethers, and chain ethers. Specific examples of cyclic esters include propylene carbonate, butylene carbonate, γ-butyrolactone, vinylene carbonate, 2-methyl-γ-butyrolactone, acetyl-γ-butyrolactone, and γ-valerolactone. Specific examples of chain esters include dimethyl carbonate, diethyl carbonate, dibutyl carbonate, dipropyl carbonate, methyl ethyl carbonate, methyl butyl carbonate, methyl propyl carbonate, ethyl butyl carbonate, ethyl propyl carbonate, butyl propyl carbonate, alkyl propionate, dialkyl malonate, and alkyl acetate. Specific examples of cyclic ethers include tetrahydrofuran, alkyltetrahydrofuran, dialkyltetrahydrofuran, alkoxytetrahydrofuran, dialkoxytetrahydrofuran, 1,3-dioxolane, alkyl-1,3-dioxolane, and 1,4-dioxolane.Specific examples of chain ethers include 1,2-dimethoxyethane, 1,2-diethoxyethane, diethyl ether, ethylene glycol dialkyl ether, diethylene glycol dialkyl ether, triethylene glycol dialkyl ether, and tetraethylene glycol dialkyl ether.

[0091] Additional Embodiments of the Disclosure When a secondary battery is assembled, the amount of carrier ions available for circulation between the anode and cathode is often initially provided at the cathode because cathode active materials such as lithium cobalt oxide are relatively stable in ambient air (e.g., they resist oxidation) compared to lithiated anode materials such as lithiated graphite. When the secondary battery is first charged, carrier ions are extracted from the cathode and introduced into the anode. As a result, the anode potential drops significantly (towards the potential of the carrier ions) and the cathode potential rises (to become more positive). These potential changes can cause parasitic reactions at both the cathode and anode, but sometimes more severely at the anode. For example, decomposition products containing lithium (or other carrier ions) and electrolyte components, known as solid electrolyte interfaces (SEIs), can easily form on the surface of carbon anodes. These surfaces or coating layers are carrier ion conductors and establish ionic bonds between the anode and the electrolyte, preventing the reaction from proceeding further.

[0092] Although the formation of the SEI layer is desirable for the stability of the half-cell system including the anode and electrolyte, a portion of the carrier ions introduced into the cell through the cathode are irreversibly bound and therefore removed from the cycling operation, i.e., from the capacity available to the user. As a result, during the initial discharge, fewer carrier ions are transferred back from the anode to the cathode than were initially provided by the cathode during the initial charging operation, resulting in irreversible capacity loss. During each subsequent charge and discharge cycle, the capacity loss resulting from mechanical and / or electrical degradation to the anode and / or cathode tends to be much less per cycle, but even the relatively small carrier ion losses per cycle contribute significantly to the reduction in energy density and cycle life as the battery ages. In addition, chemical and electrochemical degradation can also occur on the electrodes, causing capacity loss. To compensate for the formation of the SEI (or another carrier ion consumption mechanism, such as mechanical and / or electrical degradation of the negative electrode), additional or supplemental carrier ions can be provided from an auxiliary electrode after the formation of the battery.

[0093] In general, the positive electrode 208 of the secondary battery 100 (e.g., the population of negative electrode structures 206 in the secondary battery 100) preferably has a reversible coulombic capacity that matches the discharge capacity of the negative electrode 209 (e.g., the population of anode structures 207 in the secondary battery 100). Stated another way, the positive electrode 208 of the secondary battery 100 is sized to have a reversible coulombic capacity that corresponds to the discharge capacity of the negative electrode 209, which is a function of the end-of-discharge voltage of the negative electrode 209.

[0094] In some embodiments, the negative electrode 209 of the secondary battery 100 (e.g., the collective collection of positive electrode structures 207 in the secondary battery 100) is designed to have a reversible coulombic capacity that exceeds the reversible coulombic capacity of the positive electrode 208. For example, in one embodiment, the ratio of the reversible coulombic capacity of the negative electrode 209 to the reversible coulombic capacity of the positive electrode 208, respectively, is at least 1.2:1. As a further example, in one embodiment, the ratio of the reversible coulombic capacity of the negative electrode 209 to the reversible coulombic capacity of the positive electrode 208, respectively, is at least 1.3:1. As a further example, in one embodiment, the ratio of the reversible coulombic capacity of the negative electrode 209 to the reversible coulombic capacity of the positive electrode 208, respectively, is at least 2:1. As a further example, in one embodiment, the ratio of the reversible coulombic capacity of the negative electrode 209 to the reversible coulombic capacity of the positive electrode 208, respectively, is at least 3:1. As a further example, the ratio of the reversible coulombic capacity of the negative electrode 209 to the reversible coulombic capacity of the positive electrode 208 is at least 4:1, respectively. As a further example, the ratio of the reversible coulombic capacity of the negative electrode 209 to the reversible coulombic capacity of the positive electrode 208 is at least 5:1, respectively. Advantageously, the excess coulombic capacity of the negative electrode 209 provides a source of positive electrode active material, allowing the secondary battery 100 to operate reversibly within a certain voltage that inhibits the formation of crystalline phases (which incorporate carrier ions) on the negative electrode 209 that would reduce the cycle life of the negative electrode as a result of cycling.

[0095] As mentioned above, the formation of the SEI during the initial charge / discharge cycles reduces the amount of carrier ions available for reversible cycling. Mechanical and / or electrical degradation of the negative electrode 209 during cycling of the secondary battery 100 may further reduce the amount of carrier ions available for reversible cycling. Therefore, to compensate for the formation of the SEI (or another carrier ion consumption mechanism such as mechanical and / or electrical degradation of the negative electrode), additional or supplemental carrier ions can be provided from an auxiliary electrode after formation of the secondary battery 100. In an embodiment of the present disclosure, the auxiliary electrode is used to electrochemically transfer additional carrier ions to the positive electrode 208 and / or negative electrode 209 of the secondary battery 100 during and / or after formation. In one embodiment, the auxiliary electrode is removed after transferring additional carrier ions to the secondary battery 100 to improve the energy density of the final form of the secondary battery.

[0096] FIG. 5 is a perspective view of an exemplary embodiment of a buffer system 500, and FIG. 6 is an exploded view of the buffer system 500. In general, the buffer system 500 can be temporarily assembled during or after the initial formation of the secondary battery 100, and the buffer system is used to introduce additional carrier ions to the positive electrode 208 and / or negative electrode 209 of the secondary battery 100 using an auxiliary pole 502 (see FIG. 6). In this embodiment, the buffer system 500 includes an enclosure 504 that encapsulates the auxiliary pole 502 (see FIG. 6) and the secondary battery 100 within the periphery 506 of the enclosure 504. In FIG. 5, the electrical terminals 124, 125 of the secondary battery 100 and segments of the conductive tab 508-1 extend from the periphery 506 of the enclosure 504 and provide electrical connections to the auxiliary pole 502 and the secondary battery 100. In this embodiment, the enclosure 504 includes a first enclosure layer 510 and a second enclosure layer 511 joined together to form the enclosure 504 .

[0097] 6, the first enclosure layer 510 has a perimeter 512 and the second enclosure layer 511 has a perimeter 513. Each of the enclosure layers 510, 511 may include a flexible or semi-flexible material, such as aluminum, a polymer, a thin flexible metal, or the like. In one embodiment, one or more of the enclosure layers 510, 511 includes a multi-layer aluminum polymer material, plastic, or the like. In another embodiment, one or more of the enclosure layers 510, 511 includes a polymer material laminated on a metal substrate, such as aluminum. In one embodiment, the first enclosure layer 510 includes a pouch 514 (e.g., a recess) that is sized and shaped to match the exterior size and shape of the secondary battery 100.

[0098] The auxiliary pole 502 partially surrounds the secondary battery 100 in the buffer system 500 and includes a source of carrier ions to replenish the lost energy capability of the secondary battery 100 after formation (i.e., to compensate for the loss of carrier ions during the formation of the SEI and other carrier ion losses during the first charge and / or discharge cycle of the secondary battery 100). In some embodiments, the auxiliary pole 502 may include a foil of carrier ions in metallic form (e.g., a foil of lithium, magnesium, or aluminum) or any of the aforementioned materials used for the cathode active material layer 106 and / or anode active material layer 104 (see FIG. 2) in a carrier ion-containing form. For example, the auxiliary pole 502 may include lithiated silicon or a lithiated silicon alloy. When the buffer system 500 is assembled, the combination of the auxiliary pole 502, which may be referred to as an auxiliary subassembly 516 (see FIG. 6), and the secondary battery 100 is inserted into the pouch 514, and the enclosure layers 510, 511 are sealed together to form the buffer system 500 as depicted in FIG. 5. Specific details of the assembly process for the buffer system 500 and how the buffer system is used during the carrier ion transfer process to the secondary battery 100 are described in more detail below. The auxiliary pole 502 in this embodiment includes a conductive tab 508, which may be segmented, for example, for ease of manufacturing, into a conductive tab 508-1 covered by the enclosure 504 and a conductive tab 508-1 partially exposed by the enclosure, as depicted in FIG. 5.

[0099] FIG. 7 is a perspective view of an auxiliary electrode 502 according to an embodiment of the present invention, and FIG. 8 is an exploded perspective view of the auxiliary electrode. Referring to FIG. 7, the auxiliary electrode 502 includes a separator 702 covering a conductive layer 704 and a carrier ion supply layer 706. When the auxiliary electrode 502 is formed into the shape depicted in FIG. 6, the carrier ion supply layer 706 is disposed adjacent to the main surfaces 126, 127 (see FIG. 1) of the secondary battery 100, and the separator 702 insulates the casing 116 of the secondary battery 100 from the conductive layer 704 and the carrier ion supply layer 706. The separator 702 includes an electrolyte, which facilitates the movement of carrier ions from the carrier ion supply layer 706 to the secondary battery 100 during the buffering process.

[0100] 8, the auxiliary electrode 502 includes, from bottom to top in FIG. 8, a collection of a separator 702, a conductive layer 704, and a carrier ion supply layer 706. The auxiliary electrode 502 in this embodiment further includes a conductive tab 508-2, which is conductive and electrically coupled to the conductive layer 704. The conductive tab 508-2 provides an electrical connection to the auxiliary electrode 502. Generally, the auxiliary electrode 502 is used during a buffer process to transfer carrier ions from the carrier ion supply layer 706 to the positive electrode 208 and / or negative electrode 209 of the secondary battery 100 during or after formation of the secondary battery 100.

[0101] The separator 702 may include any of the materials described above with respect to the separator layer 108 of the secondary battery 100. The separator 702 may be impregnated with an electrolyte that provides a medium for conducting carrier ions from the carrier ion supply layer 706 to the positive electrode 208 of the secondary battery 100 and / or the negative electrode 209 of the secondary battery. The electrolyte may include any of the materials described above with respect to the secondary battery 100.

[0102] The separator 702 in this embodiment includes a first surface 802 and a second surface 803 opposite the first surface 802. The surfaces 802, 803 of the separator 702 form the main surface of the separator 702 and are disposed in the XY plane of FIG. 8. The separator 702 in this embodiment has a width 804 extending in the direction of the Y axis. The separator 702 in this embodiment is segmented in the width 804 into a first portion 805 and a second portion 806. In some embodiments, the separator 702 can include a first separator layer 702-1 corresponding to the first portion 805 and a second separator layer 702-2 corresponding to the second portion 806.

[0103] In one embodiment, the width 804 of the separator 702 is about 34 mm. In other embodiments, the width 804 of the separator is about 30 mm, about 35 mm, or another suitable value. In some embodiments, the width 804 of the separator 702 is within a range of values ​​from about 10 mm to about 200 mm, or any other suitable range that enables the separator to function as described herein.

[0104] The separator 702, in one embodiment, has a length 808 that extends in the direction of the X-axis. In one embodiment, the length 808 of the separator 702 is about 72 mm. In other embodiments, the length 808 of the separator 702 is about 65 mm, about 70 mm, about 75 mm, or some other suitable value that enables the separator to function as described herein. In some embodiments, the length 808 of the separator 702 is within a range of values ​​from about 30 mm to about 200 mm, or some other suitable range of values ​​that enables the separator to function as described herein.

[0105] In one embodiment, the separator 702 has a thickness 810 extending in the direction of the Z-axis. Generally, the thickness 810 is the distance from the first surface 802 of the separator 702 to (and including) the second surface 803 of the separator. In one embodiment, the thickness 810 of the separator 702 is about 0.025 mm. In other embodiments, the thickness 810 of the separator 702 is about 0.015 mm, about 0.02 mm, about 0.03 mm, about 0.035 mm, or some other suitable value. In some embodiments, the thickness 810 of the separator 702 is within a range of values ​​from about 0.01 mm to about 1.0 mm, or some other suitable range of values ​​that enables the separator to function as described herein.

[0106] The conductive layer 704 is electrically conductive and may include a metal, a metallized film, an insulating base material to which a conductive material is applied, or some other type of conductive material. In some embodiments, the conductive layer 704 includes copper. In other embodiments, the conductive layer 704 includes aluminum or another metal. In this embodiment, the conductive layer 704 is electrically coupled to a conductive tab 508-2, which is also electrically conductive. The conductive tab 508-2 has a first end 812 disposed proximate to the conductive layer 704 and a second end 813 disposed distally of the conductive layer opposite the first end 812. The first end 812 of the conductive tab 508-2 is electrically coupled to the conductive layer 704. In some embodiments, the first end 812 of the conductive tab 508-2 is spot welded to the conductive layer 704. In other embodiments, the first end 812 of the conductive tab 508-2 is soldered to the conductive layer 704. In general, the conductive tab 508-2 may be affixed to the conductive layer 704 at the first end 812 using any suitable means that ensures a mechanical and electrical connection to the conductive layer. The conductive tab 508-2 may comprise any type of conductive material as desired. In one embodiment, the conductive tab 508-2 comprises a metal. In these embodiments, the conductive tab 508-2 may comprise nickel, copper, aluminum, or other suitable metal or metal alloy that enables the conductive tab to function as described herein.

[0107] The conductive layer 704 in this embodiment includes a first surface 814 and a second surface 815 opposite the first surface 814. The surfaces 814, 815 of the conductive layer 704 form the major surfaces of the conductive layer and are disposed in the XY plane of FIG. 8. The conductive layer 704 in this embodiment has a width 816 that extends in the direction of the Y axis. In one embodiment, the width 816 of the conductive layer 704 is about 15 mm. In other embodiments, the width 816 of the conductive layer 704 is about 10 mm, about 20 mm, or any other suitable value that enables the conductive layer to function as described herein.

[0108] In some embodiments, the width 816 of the conductive layer 704 is within a range of values ​​from about 5 mm to about 100 mm, or any other suitable range of values ​​that enables the conductive layer to function as described herein. The first surface 814 of the conductive layer 704 in this embodiment is segmented into a first region 818-1 disposed proximate a first end 820 of the conductive layer 704, a second region 818-2 disposed proximate a second end 821 of the conductive layer 704, and a third region 818-3 disposed between the first region 818-1 and the second region 818-2.

[0109] The conductive layer 704 has a length 822 that extends in the direction of the X-axis. In one embodiment, the length 822 of the conductive layer 704 is about 70 mm. In other embodiments, the length 822 of the conductive layer 704 is about 60 mm, about 65 mm, about 75 mm, or some other suitable value that enables the conductive layer 704 to function as described herein. In some embodiments, the length 822 of the conductive layer 704 is within a range of values ​​from about 30 mm to about 200 mm, or some other suitable range of values ​​that enables the conductive layer to function as described herein.

[0110] The conductive layer 704 has a thickness 824 extending in the direction of the Z-axis. Generally, the thickness 824 is the distance from the first surface 814 of the conductive layer 704 to (and including) the second surface 815 of the conductive layer 704. In one embodiment, the thickness 824 of the conductive layer 704 is about 0.1 mm. In other embodiments, the thickness 824 of the conductive layer 704 is about 0.005 mm, about 0.15 mm, or about 0.2 mm. In some embodiments, the thickness 824 of the conductive layer 704 is within a range of values ​​from about 0.01 mm to about 1.0 mm, or any other suitable range of thicknesses that enable the conductive layer to function as described herein.

[0111] In one embodiment, the carrier ion supply layer 706 including the population of carrier ion supply layers includes any of the carrier ion containing materials described above that may be utilized to supply carrier ions to the positive electrode 208 and / or negative electrode 209 of the secondary battery 100. The carrier ion supply layer 706 may include one or more sources of lithium ions, sodium ions, potassium ions, calcium ions, magnesium ions, and aluminum ions. In this embodiment, the carrier ion supply layer 706 is disposed in the first region 818-1 and the second region 818-2 of the conductive layer 704. In some embodiments, the carrier ion supply layer 706 is also disposed in the third region 818-3 of the conductive layer 704.

[0112] The carrier ion supply layer 706 in this embodiment has a first surface 826 and a second surface 827 opposite the first surface 826. The surfaces 826, 827 of the carrier ion supply layer 706 form the major surfaces of the carrier ion supply layer and are disposed in the XY plane of FIG. 8. The carrier ion supply layer 706 in this embodiment has a width 828 extending in the direction of the Y axis. In one embodiment, the width 828 of the carrier ion supply layer 706 is about 15 mm. In other embodiments, the width 828 of the carrier ion supply layer 706 is about 10 mm, about 20 mm, or any other suitable value that enables the carrier ion supply layer to function as described herein. In some embodiments, the width 828 of the carrier ion supply layer 706 is within a range of values ​​between about 5 mm and about 100 mm, or any other suitable range of values ​​that enables the carrier ion supply layer to function as described herein.

[0113] The carrier ion supply layer 706, in one embodiment, has a length 830 extending in the direction of the X-axis. In one embodiment, the length 830 of the carrier ion supply layer 706 is about 23 mm. In other embodiments, the length 830 of the carrier ion supply layer 706 is about 15 mm, about 20 mm, about 25 mm, or any other suitable length that enables the carrier ion supply layer to function as described herein. In some embodiments, the length 830 of the carrier ion supply layer 706 is within a range of values ​​from about 10 mm to about 100 mm, or any other suitable range of values ​​that enables the carrier ion supply layer to function as described herein.

[0114] The carrier ion supply layer 706 has a thickness 832 extending in the direction of the Z-axis. Generally, the thickness 832 is the distance between a first surface 826 of the carrier ion supply layer 706 and a second surface 827 of the carrier ion supply layer. In one embodiment, the thickness 832 of the carrier ion supply layer 706 is about 0.13 mm. In other embodiments, the thickness 832 of the carrier ion supply layer 706 is about 0.005 mm, about 0.15 mm, or about 0.2 mm. In some embodiments, the thickness 832 of the carrier ion supply layer 706 is within a range of values ​​from about 0.01 mm to about 1.0 mm, or any other suitable range of thickness values ​​that enable the carrier ion supply layer to function as described herein.

[0115] In this embodiment, the carrier ion supply layers 706 are separated from one another by a distance 834 that corresponds to the third region 818-3. In one embodiment, the distance 834 is about 23 mm. In other embodiments, the distance 834 is about 15 mm, about 20 mm, about 25 mm, or about 30 mm. In some embodiments, the distance 834 is within a range of values ​​from about 10 mm to about 50 mm, or any other suitable range of values ​​that enables the carrier ion supply layers to function as described herein.

[0116] In one embodiment, the carrier ion supply layer 706 is sized to provide at least 15% of the reversible coulombic capacity of the positive electrode 208 of the secondary battery 100. For example, in one such embodiment, the carrier ion supply layer 706 is sized to include sufficient carrier ions (e.g., lithium, magnesium, or aluminum ions) to provide at least 30% of the reversible coulombic capacity of the positive electrode 208 of the secondary battery 100. By way of further example, in one such embodiment, the carrier ion supply layer 706 is sized to include sufficient carrier ions to provide at least 100% of the reversible coulombic capacity of the positive electrode 208 of the secondary battery 100. By way of further example, in one such embodiment, the carrier ion supply layer 706 is sized to include sufficient carrier ions to provide at least 200% of the reversible coulombic capacity of the positive electrode 208 of the secondary battery 100. By way of further example, in one such embodiment, the carrier ion supply layer 706 is sized to include sufficient carrier ions to provide at least 300% of the reversible coulombic capacity of the positive electrode 208 of the secondary battery 100. By way of further example, in one such embodiment, the carrier ion supply layer 706 is sized to include sufficient carrier ions to provide between about 100% and about 200% of the reversible coulombic capacity of the positive electrode 208 of the secondary battery 100.

[0117] During the assembly process of the auxiliary pole 502, the separator 702 may be cut from stock material or may be prefabricated to achieve the width 804 and length 808 as shown in FIG. 8. The conductive layer 704 may be cut from stock material or may be prefabricated to achieve the width 816 and length 822 shown in FIG. 8. In some embodiments, the conductive layer 704 is prefabricated to include a conductive tab 508-2 having a first end 812 mechanically and electrically affixed to the conductive layer 704 as depicted in FIG. 8. In other embodiments, the conductive tab 508-2 is cut from stock material and mechanically and electrically coupled to the conductive layer 704 (e.g., by spot welding or soldering the first end 812 to the conductive layer). In some embodiments, the carrier ion supply layer 706 is cut to size from a stock material and bonded or otherwise laminated to the conductive layer 704 (e.g., by cold welding the carrier ion supply layer 706 onto the conductive layer) to achieve the orientation depicted in Figure 8, with the second surface 827 of the carrier ion supply layer 706 in contact with the first surface 814 of the conductive layer 704. For example, the material (e.g., lithium) used to form the carrier ion supply layer 706 may be present in stock form as a roll of lithium sheets cut to size.

[0118] In another embodiment, the conductive layer 704 is prefabricated to include a carrier ion supply layer 706 arranged in the orientation depicted in Figure 8. In this embodiment, the conductive layer 704 is disposed within the first portion 805 of the separator 702 along the X-axis, and the second surface 815 of the conductive layer 704 contacts the first surface 802 of the separator.

[0119] Figure 9 is a perspective view of auxiliary pole 502 at an intermediate stage in the fabrication process of the auxiliary pole. At this stage, conductive layer 704 is disposed on first portion 805 of separator 702, and conductive tab 508-2 extends from a first end 812 attached to conductive layer 704 to the left (Y-axis direction) of Figure 9, away from separator 702 and conductive layer 704, toward a second end 813. A first surface 802 of separator 702 is covered by conductive layer 704 in first portion 805 of the separator, while first surface 802 of separator remains uncovered in second portion 806 of the separator.

[0120] To continue the fabrication process of the auxiliary pole 502, in one embodiment, the second portion 806 of the separator 702 is folded in the direction of the left-facing arrow 902 in FIG. 9 (in the X-axis direction) such that the first surface 802 in the second portion 806 of the separator 702 contacts the first surface 826 of the carrier ion supply layer 706 and the first surface 814 of the conductive layer 704 exposed between the carrier ion supply layers 706. If the separator 702 includes a first separator layer 702-1 and a second separator layer 702-2, the second separator layer may be positioned such that the first surface 802 of the second separator layer contacts the first surface 826 of the carrier ion supply layer 706 and the first surface 814 of the conductive layer 704 exposed between the carrier ion supply layers.

[0121] 10 is a perspective view of the auxiliary pole 502 at another intermediate stage in the fabrication process. At this stage, the separator 702 encapsulates the conductive layer 704 and the carrier ion supply layer 706, leaving a portion between the first end 812 of the conductive tab 508-2 and the second end 813 of the conductive tab 508-2 uncovered by the separator 702. The separator 702 can then be bonded to itself along at least a portion of the separator's periphery 1002 to encapsulate the conductive layer 704 within the separator's first portion 805 and the separator's second portion 806 along the separator's first surface 802 (not visible in FIG. 10).

[0122] In one embodiment, the separator 702 is bonded to itself along at least a portion of the separator's periphery 1002 using a hot melt process, a welding process, a bonding process, or the like. In FIG. 10, the auxiliary pole 502 at this stage includes a first side 1004 and a second side 1005 opposite the first side 1004. The first side 1004 includes the second surface 803 of the separator 702, which covers the carrier ion supply layer 706 in a first region 818-1 adjacent the first end 820 of the conductive layer 704 (not visible in FIG. 10) and in a second region 818-2 adjacent the second end 821 of the conductive layer (not visible in this view). 10, the first region 818-1 is proximate to the first end 812 of the conductive tab 508-2 and the second region 818-2 is disposed away from the first end 812 of the conductive tab 508-2. In some embodiments, the conductive tab 508-2 may extend (see FIG. 11, which depicts the auxiliary pole 502 after assembly).

[0123] Implementing a fabrication process for the buffer system 500 (see FIGS. 6 and 7) in response to fabrication of the auxiliary pole 502 continues as follows. FIGS. 12-16 are perspective views of the buffer system 500 at various stages of the fabrication process. Referring to FIG. 12, the second region 818-2 of the auxiliary pole 502 is inserted into the pouch 514 of the first enclosure layer 510, the second side 1005 of the auxiliary pole is disposed within the pouch 514 toward the first enclosure layer 510, and the first side 1004 of the auxiliary pole is disposed within the pouch away from the first enclosure layer. The third region 818-3 and the first region 818-1 of the auxiliary pole 502 extend away from the pouch 514 along the Y-axis direction.

[0124] With the auxiliary pole 502 oriented in the pouch 514 as depicted in FIG. 12, the secondary battery 100 is placed on the auxiliary pole 502 in the pouch 514 corresponding to the second region 818-2 of the auxiliary pole 502 (see FIG. 13). In this embodiment, the first major surface 126 (see FIG. 1, not visible in FIG. 13) of the secondary battery 100 contacts the auxiliary pole 502 in the pouch 514, and the second major surface 127 of the secondary battery is disposed away from the auxiliary pole 502. The electrical terminals 124, 125 of the secondary battery 100 extend away from the pouch 514 in the Y-axis direction of FIG. 13, positioning the electrical terminals outside the perimeter 512 of the first enclosure layer 510. At this stage in the fabrication process of the buffer system 500, in one embodiment, an electrolyte is added to the pouch 514. In another embodiment, the separator 702 of the auxiliary pole 502 is pre-impregnated with the electrolyte.

[0125] With the secondary battery 100 loaded onto the second region 818-2 of the auxiliary pole 502 in the pouch 514, the auxiliary pole 502 is rotated in the direction of the arrow 1302 to position the first side surface 1004 of the first region 818-1 of the auxiliary pole 502 in contact with the second main surface 127 of the secondary battery 100, the result of which is depicted in Fig. 14. In this configuration, both main surfaces 126, 127 of the secondary battery 100 (see Fig. 1) are electrochemically bonded to the carrier ion supply layer 706 of the auxiliary pole 502 using the separator 702 (see Figs. 7-11) and an electrolyte disposed between each of the main surfaces 126, 127 of the secondary battery and the carrier ion supply layer.

[0126] FIG. 15 is a cross-sectional view of the buffer system 500 taken along the line AA in FIG. 14. In this view, the layers of the buffer system 500 in the pouch 514 of the first enclosure layer 510 are visible. In particular, FIG. 15 illustrates the arrangement of the secondary battery 100 and the auxiliary pole 502 in the pouch 514, specifically, from top to bottom, the separator 702, the conductive layer 704, one of the carrier ion supply layers 706, the separator 702, and the second main surface 127 of the secondary battery 100 in the casing 116. FIG. 15 further illustrates the first enclosure layer 510, the separator 702, the conductive layer 704, one of the carrier ion supply layers 706, the separator 702, and the first main surface 126 of the secondary battery 100 in the casing 116, which are stacked in this order from bottom to top.

[0127] With the secondary battery 100 sandwiched by the auxiliary pole 502 within the pouch 514 as illustrated in FIG. 15, the second enclosure layer 511 is aligned to the first enclosure layer 510 as depicted in FIG. 16. After the second enclosure layer 511 is properly positioned relative to the first enclosure layer 510, the enclosure layers 510, 511 are sealed along a sealing line 1602 (shown by a dashed line in FIG. 16) to form the enclosure 504. The enclosure layers 510, 511 may be sealed along the sealing line 1602 by welding, heat sealing, adhesives, combinations thereof, and the like. In another embodiment, the enclosure layers 510, 511 can be sealed along three sides of the sealing line 1602 to form a pocket therein. In this embodiment, the secondary battery 100 can be placed within the pocket, and then the final edge of the sealing line 1602 is sealed. In one embodiment, the sealing line 1602 is sealed using a hot press, which applies a controlled temperature and pressure to the sealing line 1602 to bond or fuse the enclosure layers 510, 511 together along the sealing line 1602. In another embodiment, a vacuum is applied to the secondary battery 100 during the sealing process to evacuate any excess volume occupied by air or other gases. The time that the sealing line 1602 undergoes the hot press may be controlled and depends on the material selected for the enclosure layers 510, 511. When sealed over the secondary battery 100, the sealed enclosure layers 510, 511 form the buffer system 500. When sealed, the buffer system 500 is liquid-tight and / or air-tight, depending on the desired application. The electrical terminals 124-125 of the secondary battery 100 and the conductive tabs 508-1 remain exposed and are not covered by the enclosure layers 510, 511, allowing a subsequent buffering process to be applied to the secondary battery.

[0128] With the secondary battery 100 and the carrier ion supply layer 706 of the auxiliary pole 502 (not visible in FIG. 16) electrochemically bonded together within the enclosure 504 of the buffer system 500, a carrier ion buffering process is performed on the secondary battery 100 during or after the initial formation of the secondary battery. Generally, this carrier ion buffering process transfers carrier ions from the carrier ion supply layer 706 of the auxiliary pole 502 to each of the first major surface 126 of the secondary battery 100 and the second major surface 127 of the secondary battery (see FIG. 15). Generally, transferring carrier ions from both major surfaces 126, 127 of the secondary battery 100 to the secondary battery as depicted in FIG. 15 provides the technical advantage that more carrier ions are loaded into the anode and / or cathode of the secondary battery, thus distributing the forces generated by the expansion of the anode and / or cathode more evenly across the casing 116 of the secondary battery 100.

[0129] Either before or after inserting the secondary battery 100 into the buffer system 500, the secondary battery 100 is charged (e.g., via electrical terminals 124, 125) by transferring carrier ions from the secondary battery's cathode structure 206 to the secondary battery's anode structure 207. Charging may be interrupted when the secondary battery's positive electrode 208 reaches its end-of-charge design voltage. During the initial charging cycle, an SEI may form on the surface of the secondary battery's anode structure 207. To compensate for the loss of carrier ions to the SEI and to further provide additional carrier ions to mitigate long-term secondary reactions during cycling in which carrier ions are lost due to side reactions, the positive electrode 208 and / or negative electrode 209 of the secondary battery 100 can be replenished by applying a voltage across the auxiliary electrode 502 and the cathode structure 206 and / or anode structure 207 (e.g., via the conductive tab 508-1 of the auxiliary electrode 502 and one of the electrical terminals 124, 125) to drive carrier ions from the carrier ion supply layer 706 of the auxiliary electrode 502 to the cathode structure 206 and / or anode structure 207 of the secondary battery 100. Upon completion of the transfer of carrier ions from the auxiliary electrode 502 to the secondary battery 100, the negative electrode 209 of the secondary battery 100 is charged again, and this time carrier ions are transferred from the cathode structure 206 of the secondary battery to the anode structure 207 of the secondary battery.

[0130] In one embodiment, the amount of carrier ions transferred from the auxiliary electrode 502 to the secondary battery 100 during the buffering process is about 50% of the reversible coulombic capacity of the positive electrode 208 of the secondary battery. In other embodiments, the amount of carrier ions transferred from the auxiliary electrode 502 to the secondary battery 100 during the buffering process is about 55%, about 60%, about 65%, about 70%, about 75%, about 80%, about 85%, about 90%, about 95%, or about 100% of the reversible coulombic capacity of the positive electrode 208 of the secondary battery. In some embodiments, the amount of carrier ions transferred from the auxiliary electrode 502 to the secondary battery 100 is within a range of values ​​from about 1% to about 100% of the reversible coulombic capacity of the positive electrode 208 of the secondary battery. In one particular embodiment, the negative electrode 209 of the secondary battery 100 has about 170% of the reversible coulombic capacity of the positive electrode 208 of the secondary battery stored as carrier ions when the secondary battery is charged, and about 70% of the reversible coulombic capacity of the positive electrode 208 of the secondary battery stored as carrier ions when the secondary battery is discharged. The excess carrier ions in the negative electrode 209 of the secondary battery 100 provided during the buffering process provide the technical advantage of mitigating the loss of carrier ions in the secondary battery due to the SEI upon initial formation. Furthermore, the excess carrier ions in the negative electrode 209 of the secondary battery 100 provided during the buffering process provide the technical advantage of mitigating the loss of carrier ions in the secondary battery due to side reactions that deplete carrier ions in the secondary battery when the secondary battery is cycled during use, which reduces the capacity loss of the secondary battery over time.

[0131] In some embodiments, the transfer of carrier ions from the auxiliary electrode 502 to the secondary battery 100 may occur simultaneously with the initial formation of the secondary battery (e.g., during a first charge of the secondary battery) and / or during a subsequent charge of the secondary battery after the initial formation. In these embodiments, the carrier ions transfer from the positive electrode 208 of the secondary battery 100 to the negative electrode 209 of the secondary battery. Simultaneously or based on a time delay or pattern, the carrier ions transfer from the auxiliary electrode 502 to the positive electrode 208 and / or negative electrode 209 of the secondary battery 100.

[0132] In yet another embodiment, the positive electrode 208 can replenish carrier ions by transferring carrier ions from the auxiliary electrode 502 to the positive electrode 208 of the secondary battery 100 while simultaneously transferring carrier ions from the positive electrode of the secondary battery to the negative electrode 209 of the secondary battery. Referring to FIG. 6, a voltage is applied across the electrical terminals 124, 125 of the secondary battery 100 to drive carrier ions from the positive electrode 208 to the negative electrode 209 of the secondary battery. While the carrier ions are transferring from the positive electrode 208 to the negative electrode 209, a voltage is applied across the conductive tab 508-1 of the auxiliary electrode 502 and the positive electrode 208 of the secondary battery 100 to drive carrier ions from the auxiliary electrode 502 to the positive electrode 208 of the secondary battery. Thus, carrier ions are transferring from the auxiliary electrode 502 to the positive electrode 208 of the secondary battery 100 while carrier ions are transferring from the positive electrode to the negative electrode 209 of the secondary battery. That is, a voltage sufficient to drive carrier ions from the positive electrode to the negative electrode of the secondary battery is maintained across the positive electrode 208 and the negative electrode 209 of the secondary battery 100, and at the same time, a voltage sufficient to drive carrier ions from the auxiliary electrode to the positive electrode is maintained across the conductive tab 508-1 of the auxiliary electrode 502 and the positive electrode of the secondary battery. In another embodiment, the initiation of carrier ion migration from the auxiliary electrode 502 to the positive electrode 208 of the secondary battery 100 may begin simultaneously with the initiation of carrier ion migration from the positive electrode to the negative electrode 209 of the secondary battery. In one embodiment, the migration rate of carrier ions from the positive electrode 208 to the negative electrode 209 of the secondary battery 100 is equal to or greater than the migration rate of carrier ions from the auxiliary electrode 502 to the positive electrode of the secondary battery, so that a good overall migration rate of carrier ions from the auxiliary electrode to the negative electrode of the secondary battery via the positive electrode can be maintained. That is, the relative speed of the movement between the positive electrode 208 and the negative electrode 209 of the secondary battery 100 and between the auxiliary electrode 502 and the positive electrode can be maintained so as not to exceed the total capacity of the positive electrode for additional carrier ions. This allows the positive electrode 208 to be maintained in a state capable of accepting new carrier ions from the auxiliary electrode 502, and allows the subsequent movement of carrier ions to the negative electrode 209 of the secondary battery 100.

[0133] In one embodiment, without being limited by any particular theory, carrier ions migrate from the auxiliary electrode 502 to the positive electrode 208 of the secondary battery 100 as part of replenishing the negative electrode 209 of the secondary battery (as opposed to migrating directly from the auxiliary electrode to the negative electrode of the secondary battery) because the positive electrode may be able to receive carrier ions more uniformly across its surface, thus allowing the carrier ions to participate more uniformly in their migration between the positive and negative electrodes of the secondary battery.

[0134] After the buffering process is performed on the secondary battery 100 using the buffering system 500, the auxiliary pole 502 can be removed from the buffering system to improve the energy density of the secondary battery 100 in its final form. For example, after the buffering process, the carrier ion supply layer 706 (see FIG. 7) may be removed from the conductive layer 704 that has been electrochemically transferred to the secondary battery 100. Thus, the auxiliary pole 502 may not be needed at this point. To remove the auxiliary pole 502 from the enclosure 504 after the buffering process is performed, the enclosure layers 510, 511 of the enclosure may be cut along the cut lines 1702 illustrated as solid lines in FIG. 17, allowing the enclosure layers 510, 511 to be peeled away adjacent to the auxiliary pole 502. The auxiliary pole 502 is removed from the enclosure 504 of the buffering system 500, and the secondary battery 100 is left in the pouch 514 (see FIG. 12). The enclosure layers 510, 511 can then be resealed along a final sealing line 1704, illustrated as a dashed line, to form the enclosure 504 in its final form prior to use of the secondary battery 100. This resealing may be performed using any of the processes previously described for sealing the first enclosure layer 510 and the second enclosure layer 511 together.

[0135] FIG 18 is a flowchart of a method 1800 of pre-lithiating a secondary battery with carrier ions using an auxiliary electrode of an exemplary embodiment, and FIGS. 19-21 are flowcharts depicting further details of method 1800. Although method 1800 is described with respect to secondary battery 100, buffer system 500, and auxiliary electrode 502 of FIGS. 1-17, method 1800 may be applied to other systems not shown. The steps of method 1800 are not all inclusive, and method 1800 may include other steps not shown. Additionally, the steps of method 1800 may be performed in an alternate order.

[0136] In this embodiment, a secondary battery 100 (see FIG. 1 ) has opposing major surfaces 126, 127 and electrical terminals 124, 125. The electrical terminals 124, 125 are coupled to one of a positive electrode 208 of the secondary battery 100 (e.g., a group of cathode structures 206 in the secondary battery as depicted in FIG. 2 ) and a negative electrode 209 of the secondary battery (e.g., a group of anode structures 207 in the secondary battery as depicted in FIG. 2 ). Between the negative electrode 209 and the positive electrode 208, the secondary battery 100 includes an electrolyte-permeated microporous separator layer 108 (see FIG. 2 ) that is in ionic contact with the negative electrode 209 and the positive electrode 208. The negative electrode 209 includes a positive electrode active material 104, such as silicon or an alloy thereof, that has a coulombic capacity for carrier ions. The positive electrode 208 includes a negative electrode active material 106 that has a coulombic capacity of carrier ions, and the coulombic capacity of the negative electrode 209 exceeds the coulombic capacity of the positive electrode 208 .

[0137] The auxiliary pole 502 (see FIG. 6) is placed in contact with the major surfaces 126, 127 of the secondary battery 100 to form an auxiliary subassembly 516, in which the auxiliary pole 502 includes a conductive layer 704, a carrier ion supply layer 706 disposed on the conductive layer adjacent to the major surfaces 126, 127 of the secondary battery 100, a separator 702 disposed between the carrier ion supply layer and the major surfaces 126, 127 of the secondary battery, and a conductive tab 508 coupled to the conductive layer (see step 1802 of FIG. 18 and FIGS. 8-11).

[0138] The auxiliary subassembly 516 is installed within the enclosure 504, where the electrical terminals 124, 125 and the conductive tab 508 of the auxiliary pole 502 electrically extend from the periphery 506 of the enclosure 504 (see step 1804 and FIG. 16).

[0139] Carrier ions are transferred from the positive electrode 208 of the secondary battery 100 to the negative electrode 209 of the secondary battery by applying an electric potential voltage across the electrical terminals 124, 125 to at least partially charge the secondary battery (see step 1806). The charging may be interrupted when the positive electrode 208 of the secondary battery 100 reaches its end-of-charge design voltage. During the initial charging cycle, an SEI may form on the internal structural surface of the negative electrode 209 of the secondary battery 100.

[0140] To compensate for the loss of carrier ions to the SEI and to further provide additional carrier ions to mitigate long-term secondary reactions during cycling in which carrier ions are lost to side reactions, the carrier ions are transferred from the carrier ion supply layer 706 of the auxiliary pole 502 to the positive electrode 208 and / or negative electrode 209 of the secondary battery 100 by applying a potential voltage across the conductive tab 508 and one or more of the electrical terminals 124, 125 of the secondary battery (see step 1808 of FIG. 16). Generally, this carrier ion buffering process transfers carrier ions from the carrier ion supply layer 706 of the auxiliary pole 502 to each of the first major surface 126 of the secondary battery 100 and the second major surface 127 of the secondary battery (see FIG. 15). Generally, transferring carrier ions from both major surfaces 126, 127 of the secondary battery 100 into the secondary battery, as depicted in FIG. 15 , provides the technical advantage that more carrier ions are loaded into the cathode and / or anode of the secondary battery 100, thereby distributing forces generated by expansion of the anode and / or cathode more evenly across the casing 116 of the secondary battery.

[0141] In one embodiment, the amount of carrier ions transferred from the auxiliary electrode 502 to the secondary battery 100 is about 50% of the reversible coulombic capacity of the positive electrode 208 of the secondary battery. In other embodiments, the amount of carrier ions transferred from the auxiliary electrode 502 to the secondary battery 100 is about 55%, about 60%, about 65%, about 70%, about 75%, about 80%, about 85%, about 90%, about 95%, or about 100% of the reversible coulombic capacity of the positive electrode 208 of the secondary battery. In some embodiments, the amount of carrier ions transferred from the auxiliary electrode 502 to the secondary battery 100 is within a range of values ​​from about 1% to about 100% of the reversible coulombic capacity of the positive electrode 208 of the secondary battery. In one particular embodiment, the negative electrode 209 of the secondary battery 100 has about 170% of the reversible coulombic capacity of the positive electrode 208 of the secondary battery stored as carrier ions when the secondary battery is charged, and about 70% of the reversible coulombic capacity of the positive electrode 208 of the secondary battery stored as carrier ions when the secondary battery is discharged. The excess carrier ions in the negative electrode 209 of the secondary battery 100 provided during the buffering process provide the technical advantage of mitigating the loss of carrier ions in the secondary battery due to the SEI upon initial formation. Furthermore, the excess carrier ions in the negative electrode 209 of the secondary battery 100 provided during the buffering process provide the technical advantage of mitigating the loss of carrier ions in the secondary battery due to side reactions that deplete carrier ions in the secondary battery when the secondary battery is cycled during use, which reduces the capacity loss of the secondary battery over time.

[0142] In some embodiments, the transfer of carrier ions from the auxiliary electrode 502 to the secondary battery 100 may occur simultaneously with the initial formation of the secondary battery (e.g., during a first charge of the secondary battery) and / or during a subsequent charge of the secondary battery after the initial formation. In these embodiments, the carrier ions transfer from the positive electrode 208 of the secondary battery 100 to the negative electrode 209 of the secondary battery. Simultaneously or based on a time delay or pattern, the carrier ions transfer from the auxiliary electrode 502 to the positive electrode 208 and / or negative electrode 209 of the secondary battery 100.

[0143] The carrier ions are again transferred from the positive electrode 208 of the secondary battery 100 to the negative electrode 209 of the secondary battery by applying a potential voltage across the electrical terminals 124, 125 of the secondary battery, charging the secondary battery until the negative electrode 209 has more than 100% of the coulombic capacity of the positive electrode 208 stored as carrier ions (see step 1810).

[0144] In yet another embodiment, the positive electrode 208 can be replenished with carrier ions by transferring carrier ions from the auxiliary electrode 502 to the positive electrode 208 of the secondary battery 100 while simultaneously transferring carrier ions from the positive electrode 208 of the secondary battery to the negative electrode 209 of the secondary battery. Referring to FIG. 6, a voltage is applied across the electrical terminals 124, 125 of the secondary battery 100 to drive carrier ions from the positive electrode 208 of the secondary battery to the negative electrode 209 of the secondary battery. While the carrier ions are transferring from the positive electrode 208 to the negative electrode 209, a voltage is applied across the conductive tab 508-1 of the auxiliary electrode 502 and the positive electrode 208 of the secondary battery 100 to drive carrier ions from the auxiliary electrode 502 to the positive electrode 208 of the secondary battery. Thus, carrier ions transfer from the auxiliary electrode 502 to the positive electrode 208 of the secondary battery 100 while carrier ions are transferring from the positive electrode 208 to the negative electrode 209 of the secondary battery. That is, a voltage sufficient to drive carrier ions from the positive electrode 208 to the negative electrode 209 of the secondary battery is maintained across the positive electrode 208 and the negative electrode 209 of the secondary battery 100, and at the same time, a voltage sufficient to drive carrier ions from the auxiliary electrode 502 to the positive electrode 208 is maintained across the conductive tab 508-1 of the auxiliary electrode 502 and the positive electrode 208 of the secondary battery. In another embodiment, the initiation of carrier ion migration from the auxiliary electrode 502 to the positive electrode 208 of the secondary battery 100 may begin simultaneously with the initiation of carrier ion migration from the positive electrode 208 to the negative electrode 209 of the secondary battery. In one embodiment, the migration rate of carrier ions from the positive electrode 208 to the negative electrode 209 of the secondary battery 100 is equal to or greater than the migration rate of carrier ions from the auxiliary electrode 502 to the positive electrode 208 of the secondary battery 100, so that a good overall migration rate of carrier ions from the auxiliary electrode 502 to the negative electrode 209 of the secondary battery via the positive electrode can be maintained. That is, the relative speed of the movement between the positive electrode 208 and the negative electrode 209 of the secondary battery 100 and between the auxiliary electrode 502 and the positive electrode can be maintained so as not to exceed the total capacity of the positive electrode for additional carrier ions. This allows the positive electrode 208 to be maintained in a state capable of accepting new carrier ions from the auxiliary electrode 502, and allows the subsequent movement of carrier ions to the negative electrode 209 of the secondary battery 100.

[0145] In one embodiment, without being limited by any particular theory, carrier ions are transferred from the auxiliary electrode 502 to the positive electrode 208 of the secondary battery 100 as part of replenishing the negative electrode 209 of the secondary battery (as opposed to transferring directly from the auxiliary electrode 502 to the negative electrode of the secondary battery) because the positive electrode may be able to receive carrier ions more uniformly across its surface, thus allowing the carrier ions to participate more uniformly in their transfer between the positive and negative electrodes of the secondary battery.

[0146] In some embodiments of method 1800, enclosure 504 is opened (see step 1902 of FIG. 19 ) and auxiliary pole 502 is removed from enclosure 504 (see step 1904). In response to removing auxiliary pole 502 from enclosure 504, the enclosure is resealed to its final form to enclose secondary battery 100 for use (see step 1906). In other embodiments, auxiliary pole 502 is not removed from enclosure 504.

[0147] As previously described with respect to step 1804 detailed above, one particular embodiment installs the auxiliary subassembly 516 within the enclosure 504, but includes installing the auxiliary subassembly 516 on the first enclosure layer 510 (see step 2002 of FIG. 20). A second enclosure layer 511 is installed on the first enclosure layer 510 (see step 2004), and the first enclosure layer 510 and the second enclosure layer 511 are sealed together along the sealing line 1602 to form the enclosure 504 (see step 2006).

[0148] The enclosure layers 510, 511 may be sealed along a sealing line 1602 (see FIG. 16 ) by welding, heat sealing, adhesives, combinations thereof, and the like. In another embodiment, the enclosure layers 510, 511 may be sealed along three sides of the sealing line 1602 to form a pocket therein. In this embodiment, the secondary battery 100 may be placed in the pocket, after which the final edge of the sealing line 1602 is sealed. In one embodiment, the sealing line 1602 is sealed using a hot press, which applies a controlled temperature and pressure to the sealing line 1602 to bond or fuse the enclosure layers 510, 511 together along the sealing line 1602. In another embodiment, a vacuum is applied to the secondary battery 100 during the sealing process to evacuate any excess volume occupied by air or other gases. The time that the sealing line 1602 undergoes the hot press may be controlled and depends on the material selected for the enclosure layers 510, 511. When sealed over the secondary battery 100, the sealed enclosure layers 510, 511 form the cushioning system 500. When sealed, the cushioning system 500 is liquid-tight and / or air-tight, depending on the desired application. The electrical terminals 124, 125 and the conductive tabs 508 of the secondary battery 100 remain exposed and are not covered by the enclosure layers 510, 511.

[0149] In embodiments in which the first enclosure layer 510 includes a pouch 514, placing the auxiliary subassembly 516 in the enclosure 504 includes first disposing the auxiliary subassembly 516 in the pouch 514 (see step 2102 of FIG. 21 ). In some embodiments, electrolyte is added to the pouch (e.g., either before or after placing the auxiliary subassembly 516 in the pouch 514), and then the enclosure 504 is formed by sealing the first enclosure layer 510 and the second enclosure layer 511 together along the seal line 1602.

[0150] In some embodiments, one or more steps of the forming process performed on the secondary battery 100 discussed above may be performed using a battery tray and a forming base removably attachable to the battery tray.

[0151] 22 is a block diagram of an exemplary cell formation system 2200 for a lithium-based secondary battery, such as secondary battery 100. System 2200 includes a battery tray 2202, a forming base 2204, a loading station 2206, a charging station 2208, and a forming station 2210. Battery tray 2202 and forming base 2204, when attached, form a forming assembly 2209. Other embodiments do not include charging station 2208, and batteries to be processed by cell formation system 2200 may be charged using any suitable charging system.

[0152] The battery tray 2202 includes battery slots 2212 and a first assembly connector 2213. Each battery slot 2212 is configured (e.g., sized and shaped) to receive and hold a secondary battery 100. In an exemplary embodiment, each battery slot 2212 is configured to receive only one secondary battery 100, although in other embodiments, each battery slot may be configured to receive two or more batteries. In one exemplary embodiment, the battery tray 2202 includes 120 battery slots 2212 arranged in three rows of 40 battery slots. Other embodiments include more or fewer battery slots 2212 arranged in more or fewer rows. Openings are defined in the bottom of the battery tray 2202 at locations corresponding to the battery slots 2212 to allow the first terminal 124, the second terminal 125, and the conductive tab 508-1 to extend through the bottom of the battery tray when the secondary battery 100 is positioned in the battery slot 2212.

[0153] The forming base 2204 is designed to be similar in size and shape to the battery tray 2202 and is configured to removably attach to the battery tray. The forming base 2204 includes a connector group 2214, a pre-lithiated module 2216, and a second assembly connector 2218. Each connector group 2214 is configured to make an electrical connection to the conductive tab 508-1 and one of the first terminal 124 and the second terminal 125 of the different secondary battery 100 when the battery tray 2202 with the secondary battery loaded therein is attached to the forming base. One of the first terminal 124 and the second terminal 125 of the different secondary battery 100 to which the connector group 2214 connects is a negative terminal. In other embodiments, each connector group 2214 is configured to make an electrical connection to the conductive tab 508-1 and one of the first terminal 124 and the second terminal 125 of the different secondary battery 100 when the battery tray 2202 with the secondary battery loaded therein is attached to the forming base.

[0154] Each pre-lithiation module 2216 is electrically connected to a different one of the connector groups 2214 and configured to diffuse lithium into the electrode active material of the secondary battery 100 connected to the connector group to which the pre-lithiation module is electrically connected. In other embodiments, each pre-lithiation module 2216 is electrically connected to more than one of the connector groups 2214 and configured to diffuse lithium into the electrode active material of the secondary battery 100 connected to the two or more connector groups to which the pre-lithiation module is electrically connected. In one example, the pre-lithiation module 2216 is a switched capacitor circuit. In another example, the pre-lithiation module 2216 includes a resistor electrically connected between the conductive tab 508-1 and one of the first terminal 124 and the second terminal 125, and a circuit that interrupts the connection when the voltage drops to 1.5V (indicating completion of the buffering process). Other embodiments include any other suitable pre-lithiation module. In some embodiments, each pre-lithiated module is separate from each other pre-lithiated module, while in other embodiments, two or more pre-lithiated modules are integrated into a common circuit or mounted on a common support (such as a rigid circuit board, a flexible circuit board, or other suitable support).

[0155] The second assembly connector 2218 is configured to matingly engage with the first assembly connector 2213 to mechanically connect the battery tray 2202 to the forming base 2204. In one exemplary embodiment, the first assembly connector 2213 is a rectangular opening through the bottom of the battery tray 2202 and the second assembly connector 2218 is a rotatable T-shaped connector extending from the forming base 2204. In a first orientation, the second assembly connector 2218 can pass through the rectangular opening of the first assembly connector 2213 to allow the battery tray 2202 to be placed in a predetermined position on the forming base 2204. When the second assembly connector 2218 is rotated to a second position (e.g., 90 degrees from the first position), the second assembly connector cannot pass through the rectangular opening of the first assembly connector 2213. Thus, after the battery tray 2202 is placed in place on the forming base 2204, the second assembly connector 2218 is rotated to a second position to lock the battery tray and forming base together within the forming assembly 2209. Other embodiments may use other connection systems as the first and second assembly connectors.

[0156] The loading station 2206, the charging station 2208, and the forming station 2210 are stations for loading the batteries 100 into the battery trays 2202, charging the batteries in the battery trays, and buffering the batteries in the forming assembly 2209, respectively. In the loading station 2206, the secondary batteries 100 are typically loaded into the battery trays 100 by a robotic loader (not shown). In other embodiments, the secondary batteries 100 are loaded into the battery trays 2202 by a human operator. The charging station 2208 is configured to receive the battery trays 2202 loaded with the batteries 100, store the loaded battery trays, and charge the batteries 100 in the battery trays. The forming station 2210 is configured to receive the forming assembly 2209 including the battery trays 2202 loaded with the charged batteries 100, and store the forming assembly while lithium is diffused into the electrode active material of the secondary batteries in the battery trays by the pre-lithiation module 2216. Some embodiments also include a loading station (not shown) at which the battery tray 2202 is loaded to the forming base 2204. The battery tray 2202 and forming assembly 2209 can move between the loading station 2206, the charging station 2208, the forming station 2210, and the loading station on a conveyor belt or any other suitable transport system.

[0157] The charging station 2208 includes a rack or shelving system for storing the battery trays 2202, as well as electrical connections for providing power to the battery trays to charge the secondary batteries 100 therein. In some embodiments, the charging station includes charging circuitry for controlling the charging of the batteries 100, while in other embodiments the charging circuitry is included within the battery trays 2202 or forming base 2204. In some embodiments, the charging station 2208 also includes communications connections that allow one or more remote computing devices to control and / or monitor the charging of the secondary batteries 100 at the charging station 2208.

[0158] The forming station 2210 includes a rack or shelving system for storing the forming assemblies 2209, as well as electrical connections for providing power to the forming process. In some embodiments, the forming station 2210 also includes communication connections that allow one or more remote computing devices to control and / or monitor the forming process at the forming station 2210.

[0159] 23 is a diagram of an exemplary battery tray that may be used as the battery tray 2202. The battery tray includes sides 2300 that are connected to and extend above a base 2302. In the exemplary embodiment, the battery tray 2202 includes four sides 2300 of approximately equal length, height, and thickness. In other embodiments, the battery tray may include more or fewer sides 2300 and / or the sides may vary in one or more of their dimensions. The exemplary battery tray 2202 includes 120 battery slots 2212 arranged in three columns 2304 of 40 slots each. Other embodiments may include more or fewer total slots 2212 arranged in more or fewer rows 2304. At least one opening (not shown in FIG. 23 and shown as 2800 in FIG. 28) is defined through the base 2302 at the location of each slot 2212 to allow the conductive tabs 508-1, the first terminals 124, and the second terminals 125 to extend from the slots 2212 through the base of the battery tray 2202 to a location accessible from the underside 2306 of the battery tray's base. The battery tray 2202 includes six first assembly connectors 2213 (not shown in FIG. 23) for matingly engaging with six corresponding second assembly connectors 2218 of the formed base 2204 to mechanically connect the battery tray 2202 to the formed base 2204. Other embodiments may include more or fewer first assembly connectors 2213 and second assembly connectors 2218.

[0160] FIG. 24 is a diagram of an exemplary forming base that may be used as the forming base 2204. The forming base includes as many connector groups 2214 as the battery tray 2202 has battery slots 2212. Three connector groups 2214 are shown in FIG. 25. The exemplary forming base 2204 includes six second assembly connectors 2218 (three on each side, only one visible in FIG. 24) for mating engagement with the first assembly connectors 2213 of the battery tray 2202 to mechanically connect the battery tray 2202 to the forming base 2204.

[0161] FIG. 26 is a side view of the battery tray 2202 positioned to attach to the forming base 2204 to form a forming assembly 2209. FIGS. 27-29 show the process of engaging one of the second assembly connectors 2218 of the forming base 2204 with one of the first assembly connectors 2213 of the battery tray 2202. During connection of the battery tray 2202 to the forming base 2204, the same process will occur for each first assembly connector 2213 and second assembly connector 2218. As seen in FIG. 27, the battery tray 2202 is positioned on the forming base 2204 with the first assembly connector 2213 aligned over the second assembly connector 2218. In this embodiment, the first assembly connector 2213 is a rectangular opening and the second assembly connector 2218 includes a rotatable rectangular bar 2700 supported above the base 2702 by posts 2704. The rectangular bar 2700 is sized to fit through a rectangular opening in the first assembly connector 2213, and the posts 2704 are sized to be approximately the same height as the thickness of the battery tray base 2302, or slightly greater above the base 2702. When starting to assemble the forming assembly 2209, the second assembly connector 2218 is oriented with the rectangular bar in a first orientation that will allow it to pass through the rectangular opening in the first assembly connector 2213 when lowering the battery tray (or raising the forming base) to connect the battery tray and forming base. The forming base 2702 also has a group of alignment posts 2706 (only one of which is shown in FIG. 27) that correspond to alignment holes 2708 in the battery tray 2202. When the battery tray 2202 is positioned on the forming base 2204, the alignment posts 2706 pass into the alignment holes to help align the forming base and the battery tray and to limit movement of the battery tray relative to the forming base in a plane parallel to the base 2702.

[0162] In FIG. 28, the battery tray 2202 has been lowered onto the forming base 2204 and the rectangular bar 2700 of the second assembly connector 2218 has passed through the rectangular opening of the first assembly connector 2213. The rectangular bar 2700 is now still in the first orientation and the battery tray 2202 can be lifted and removed from the forming base 2204. In FIG. 29, the rectangular bar 2700 has been rotated to a second orientation. In the second orientation, the rectangular bar 2700 of the second assembly connector 2218 cannot pass through the opening of the first assembly connector 2213, thereby securing the battery tray 2202 to the forming base 2204. The second orientation is approximately 90 degrees from the first orientation, but the two orientations can differ by any angle sufficient to allow passage of the rectangular bar 2700 through the opening in the first assembly connector 2213 in the first orientation and to prevent passage of the rectangular bar 2700 through the opening in the first assembly connector 2213. Other embodiments may use any other suitable types of connectors for the first and second assembly connectors.

[0163] Described below is one exemplary method of cell formation using cell formation system 2200. It should be understood that cell formation system 2200 may also be used for other methods of cell formation.

[0164] First, a group of lithium-based secondary batteries 100 are loaded into the battery tray 2202. Each battery 100 is loaded into a different battery slot 2212 having a conductive tab 508-1, a first terminal 124, and a second terminal 125 extending through the battery tray base 2302 to a position accessible from the underside of the battery tray base. The battery tray 2202 is then transported to a charging station 2208, where the lithium-based secondary batteries 100 in the battery tray are charged. The battery tray 2202 is removed from the charging station 2208, and the forming base 2204 is attached to the battery tray from the underside of the battery tray base 2302 to form a forming assembly 2209. The forming assembly 2209 is transported to the forming station 2210, and the lithium-based secondary batteries 100 in the forming assembly 2209 are pre-lithiated using the pre-lithiated module 2216. The forming base 2204 is removed from the battery tray 2202 after pre-lithiation is completed. One or more additional processes may be performed on the lithium-based secondary batteries 100 in the battery tray 2202. The forming base 2204 is returned for reuse while the additional processes are performed. Thus, additional populations of lithium-based secondary batteries 100 can be loaded into additional battery trays 2202, and the above process can be repeated with additional battery trays 2202 and forming bases 2204.

[0165] In some embodiments, the formation process is performed by a distributed formation system (which may include cell formation system 2200), in which each secondary battery 100 is connected to a separate formation cluster that performs the formation process for the secondary battery 100 to which it is connected. In embodiments using cell formation system 2200, a separate formation cluster for each secondary battery 100 may be included in formation base 2204. In such embodiments, charging and discharging may occur with formation base 2204 attached to the battery tray, or may occur within the battery tray without formation base 2204 attached (e.g., charging and discharging modules may be in the battery tray and pre-lithiation module may be in the formation base).

[0166] 30 is a block diagram of an exemplary cell formation system 3000 for a lithium-based secondary battery, such as the secondary battery 100. The cell formation system includes a population of formation clusters 3002 and a central controller 3004. Each formation cluster 3002 is connected to a secondary battery 100 and performs a formation process on the connected secondary battery 100.

[0167] The forming clusters 3002 are communicatively coupled to the central controller 3004 by a network 3006. The network 3006 may be any type of wired or wireless network suitable for communication between the forming clusters 3002 and the central controller 3004. For example, the network 3006 may be an Inter-Integrated Circuit (I2C) network, a Controller Area Network (CAN), a Local Area Network (LAN), a Wide Area Network (WAN), etc. Although shown connected to the same network 3006 in FIG. 30, the forming clusters 3002 and the central controller 3004 may be connected to different networks or a combination of the same and different networks. For example, some of the forming clusters 3002 may be connected to a first LAN and some of the forming clusters may be connected to a second LAN, and the first and second LANs may be connected to the central controller 3004 through a WAN that is connected to both the first and second LANs.

[0168] Each forming cluster 3002 is connected to a power source 3008, such as a power grid, a generator, a solar power system, a battery, etc. The forming cluster 3202 uses power from the power source 3008 to power the forming cluster and perform the forming process. Although illustrated in Figure 30 as being connected to the same power source 3008, the forming clusters 3002 in the cell forming system 3000 may be connected to different power sources.

[0169] The group of forming clusters 3002 are supported by a housing 3010. The housing 3010 can be an enclosure such as a cabinet, or an open support such as a rack. For simplicity, two forming clusters 3002 are shown in one housing 3010 and a single forming cluster 3002 is shown in another housing, but in practice, each housing 3010 will typically support a larger number of forming clusters, such as 10, 25, 50, 100, 250, or 1000 forming clusters. Notably, the central controller 3004 is separate from (and may be located remotely from) the housings 3010 and their forming clusters 3002. Furthermore, the housings 3010 may be located in different locations from each other, so long as they are located anywhere with access to a power source 3008 and a network 3006. Furthermore, each housing 3010 can support a different number of forming clusters 3002.

[0170] 31 is a block diagram of an example formation cluster 3002. The formation cluster 3002 includes a battery connector 3100, a charging module 3102, a pre-lithiation module 3104 (sometimes referred to as a buffer module), a discharging module 3106, a communication interface 3108, a formation cluster controller 3110, a power connection 3112, a power supply unit (PSU) 3113, and a sensor 3114.

[0171] The battery connector 3100 connects the forming cluster 3002 to the secondary battery 100. The battery connector 3100 may be any connector suitable for connecting to the secondary battery 100, including a connector configured to mate with a similar connector on the battery, a clamp connector (such as an alligator clip), wires soldered or welded to the battery and the forming cluster 3002, and the like. The battery connector 3100 is configured to connect to the positive and negative poles of the secondary battery 100. In some embodiments, the battery connector 3100 also electrically connects the forming cluster 3002 to the auxiliary pole 502. In other embodiments, the forming cluster 3002 includes a separate connector, referred to as a pre-lithiated connector, that electrically connects the forming cluster 3002 to the auxiliary pole 502. In some embodiments, the forming cluster 3002 includes two or more battery connectors 3100, each battery connector connected to a separate one of the modules of the forming cluster.

[0172] The charging module 3102 is connected to the battery connector 3100 and configured to charge the secondary battery 100 connected to the battery connector 3100. The pre-lithiation module 3104 is connected to the battery connector 3100 and configured to diffuse lithium carrier ions to the electrode active material layers (cathode active material layer 106 and / or anode active material layer 104) of the secondary battery 100. The discharging module 3106 is connected to the battery connector 3100 and configured to discharge the secondary battery 100.

[0173] The communication interface 3108 connects the forming clusters 3002 to the central controller 3004. The communication interface 3108 may be any wired or wireless communication interface that allows the controllers to communicate with the communication central controller 3004 directly or over a network. The wireless communication interface 3108 may include a radio frequency (RF) transceiver, a Bluetooth adapter, a Wi-Fi transceiver, a ZigBee transceiver, an infrared (IR) transceiver, and / or any other device and communication protocol connection for wireless communication. (Bluetooth is a registered trademark of the Bluetooth Special Interest Group, Kirkland, Washington, and ZigBee is a registered trademark of the ZigBee Alliance, San Ramon, California.) The wired communication interface 3108 may use any suitable wired communication protocol for direct communication, including but not limited to USB, RS232, I2C, SPI, analog, and proprietary I / O protocols. In some embodiments, the wired communication interface 3108 includes a wired network adapter that allows the controller to be coupled to a network, such as the Internet, a local area network (LAN), a wide area network (WAN), a mesh network, and / or any other network for communicating with remote devices and systems via the network.

[0174] The formation cluster controller 3110 controls the operation of the formation cluster 3002 to operate as described herein. The formation cluster includes a processor 3116 and a memory 3118. The processor 3116 is any programmable system including a microcontroller, a microcomputer, a microprocessor, a reduced instruction set circuit (RISC), an application specific integrated circuit (ASIC), a programmable logic circuit (PLC), and any other circuit or processor capable of performing the functions described herein. The memory 3118 stores computer readable instructions executable by the processor 3116 for control of the formation cluster 3002 as described herein. The memory 3118 can be any suitable type of memory, such as, but not limited to, a random access memory (RAM), such as a dynamic RAM (DRAM) or a static RAM (SRAM), a read only memory (ROM), an erasable programmable read only memory (EPROM), an electrically erasable programmable read only memory (EEPROM), and a non-volatile RAM (NVRAM). In some embodiments, the processor 3116 and the memory 3118 are both embodied within a microcontroller, while in other embodiments, the processor 3116 and the memory 3118 are separate components.

[0175] In an exemplary embodiment, the formation cluster controller 3110 is programmed (by instructions stored in memory 3118) to directly control each of the modules 3102, 3104, and 3106. That is, the formation cluster controller 3110 is programmed to control the charging module for charging the secondary battery 100, the pre-lithiation module 3104 for pre-lithiating (also referred to as buffering) the secondary battery 100, and the discharge module 3106 for discharging the secondary battery 100. The formation cluster controller 3110 is also programmed to control the entire formation process, including which modules to use and when.

[0176] In other embodiments, one or more of the modules 3102, 3104, and 3106 include their own module controllers (with processors and memory). In such embodiments, the formation cluster controller 3110 controls the entire formation process, but the module controllers control the specific tasks of those modules. For example, the formation cluster controller 3110 may instruct the charging module 3102 to charge the secondary battery 100, and then the module controller in the charging module will control the charging module to charge the secondary battery 100 according to instructions stored in the memory of the module controller of the charging module.

[0177] In further embodiments, the forming cluster 3002 does not include a forming cluster controller 3110. Rather, each of the modules 3102, 3104, and 3106 includes its own module controller. In such embodiments, the central controller 3004 controls the entire forming process and sends instructions to the module controllers through the communication interface 3108. In such embodiments, the multiple module controllers in the forming cluster 3002 can be considered a distributed forming cluster controller 3110.

[0178] Various levels of interaction and control may be performed by the central controller 3004 and the forming cluster controller 3110 in different embodiments. For example, in some embodiments, the central controller 3004 simply sends instructions to the forming cluster 3002 to start the forming process. Then, in response to the instructions, the forming cluster controller 3110 controls the modules 3102, 3104, and 3106 to perform the forming process. Alternatively, in response to the instructions, the forming cluster controller 3110 may instruct the modules 3102, 3104, and 3106 to perform their functions at the appropriate times. In other embodiments, the central controller 3004 sends instructions to the forming cluster 3002 to perform individual parts of the forming process (e.g., "charge the battery here"), and the forming cluster controller 3110 or the module controllers perform the tasks instructed by the central controller. In some embodiments, the central controller 3004 may send instructions to the forming cluster 3002 on how to perform one or more of the forming tasks, including sending a control algorithm. In some embodiments, the forming cluster controller 3110 or module controller may store instructions for multiple methods of performing the same task (e.g., fast charging, slow charging, charging with rest periods, etc.), and the central controller's instructions may instruct the forming cluster 3002 which method to use.

[0179] In some embodiments, the central controller 3004 can program or update the programming of the formation cluster controllers 3110 or the module controllers. For example, the central controller 3004 can send a control algorithm to the formation cluster 3002, and the formation cluster controller 3110 and / or the module controllers can store the control algorithm in their respective memories. In other embodiments, the central controller can send modifications to a control algorithm already stored in the formation cluster, such as changing variables, changing timing, etc. The formation cluster controller 3110 or the controller module then stores the modifications in memory for use in the formation process.

[0180] The formation cluster controller 3110, in some embodiments, also transmits information back to the central controller 3004. The information sent to the central controller 3004 may include confirmation that the command was received, confirmation that the commanded process has begun, the status of the operation being performed, data collected from the sensors 3114, or any other suitable information.

[0181] The power connection 3112 connects the forming cluster 3002 to the power source 3008. 3100 can be any connector suitable for connection to the power source 3008, including a plug configured to insert into a mating socket of the power source, wires soldered or welded to the power source, a clamp connector for clamping to the terminals or wires of the power source, etc. The PSU 3113 converts and / or distributes power from the power source to the remainder of the forming cluster 3002 for use in the forming process. The PSU 3113 may be an AC / DC power converter, a DC / DC power converter, an inverter, or any other unit suitable for converting power and / or distributing power to the forming cluster. Some embodiments do not include a PSU and utilize power directly from the power source 3008.

[0182] The sensor 3114 is any sensor capable of monitoring a variable important to the formation process. For example, the sensor 3114 may be a voltage sensor for monitoring the voltage of the secondary battery 100, an ambient temperature sensor for monitoring the temperature surrounding the formation cluster 3002, a temperature sensor for monitoring the temperature of the battery assembly or components of the formation cluster, a current sensor for monitoring the current flowing into, out of, or through the battery assembly, etc. Some embodiments include more than one sensor 3114, including a combination of the aforementioned sensors. Furthermore, some sensors 3114 may perform more than one of the above-mentioned monitoring tasks.

[0183] The modular and distributed nature of the cell formation system 3000 allows the system to be easily expanded or contracted as desired. Unlike conventional centralized systems that are configured to form a set number of batteries at a time, the system 3000 can be expanded to any number of batteries by simply adding more forming modules (including increasing the number of batteries by as little as one additional battery). In conventional centralized systems, increasing the number of batteries formed requires the acquisition of additional systems and an increase in a set number of batteries (determined by the size and configuration of the centralized system obtained). Furthermore, centralized systems typically require running significant additional wiring to each additional battery to provide controlled power and communication to the additional batteries. In contrast, the cell formation system 3000 only requires connecting the additional forming modules 3002 to a power source and an existing communication network. The cell formation clusters 3002 in the system 3000 do not all need to be the same, as long as the central controller 3004 knows the configuration of each cluster. Furthermore, different batteries can be formed at different times or simultaneously using the cell forming clusters 3002 in the system 3000, as long as the central controller 3004 or forming cluster controller 3110 is aware of which secondary batteries 100 are connected to the forming cluster.

[0184] 32 is a block diagram of an exemplary pre-lithiation module 3104 for use in the cell formation cluster 3002. As described above, the pre-lithiation module 3104 is configured to diffuse lithium into an electrode active material layer of the secondary battery 100. The pre-lithiation module 3104 includes a switched capacitor circuit 3200, a pre-lithiation module controller 3202, a battery connector 3204, a pre-lithiation connector 3206, and a communication interface 3208.

[0185] The switched capacitor circuit 3200 is a switched resistor-capacitor network. The switched capacitor circuit 3200 is described in more detail below with reference to FIG. 33. Generally, in a first stage, a current can be passed through the circuit to charge the capacitor network, and then in a second stage, the energy stored in the capacitor network is discharged through a discharge resistor and released as heat. In the pre-lithiation module 3104, a current can be passed between the auxiliary electrode 502 and one of the electrodes of the secondary battery 100 to diffuse lithium from the auxiliary electrode 502 to the electrode active material layer of the secondary battery 100.

[0186] The pre-lithiation module controller 3202 controls the operation of the pre-lithiation module 3104 to pre-lithiate the secondary battery 100 by selectively passing current through the auxiliary electrode 502 to diffuse lithium into the electrode active material layer of the battery assembly. The pre-lithiation module controller 3202 includes a processor 3210 and a memory 3212. The memory 3212 stores instructions that, when executed by the processor 3210, cause the processor to perform pre-lithiation as described herein. The processor 3210 is any programmable system, including a microcontroller, microcomputer, microprocessor, reduced instruction set circuit (RISC), application specific integrated circuit (ASIC), programmable logic circuit (PLC), and any other circuit or processor capable of performing the functions described herein. The memory 3212 may be any suitable type of memory, including, but not limited to, random access memory (RAM), such as dynamic RAM (DRAM) or static RAM (SRAM), read only memory (ROM), erasable programmable read only memory (EPROM), electrically erasable programmable read only memory (EEPROM), and non-volatile RAM (NVRAM). In some embodiments, the processor 3210 and memory 3212 are both embodied within a microcontroller, while in other embodiments, the processor and memory are separate components.

[0187] The battery connector 3204 connects the pre-lithiation module 3104 to the secondary battery 100. The battery connector 3204 may be the battery connector 3100 or may be a separate battery connector connected only to the pre-lithiation module 3104. The battery connector 3204 may be any connector suitable for connection to the secondary battery 100, including a connector configured to mate with a similar connector on the battery, a clamp connector (such as an alligator clip), wires soldered or welded to the battery and the pre-lithiation module 3104, etc. The battery connector 3204 is configured to connect to the positive and negative poles of the secondary battery 100.

[0188] The pre-lithiated connector 3206 connects the pre-lithiated module 3104 to the auxiliary pole 502 of the secondary battery 100. The pre-lithiated connector 3204 may be any connector suitable for connection to the secondary battery 100, including a connector configured to mate with a similar connector on the battery, a clamp connector (such as an alligator clip), wires soldered or welded to the battery and pre-lithiated module 3104, etc. In some embodiments, the pre-lithiated connector 3206 is part of the battery connector 3100.

[0189] The communication interface 3208 connects the pre-lithiation module 3104 to the central controller 3004. The communication interface 3208 may be the communication interface 3108 or may be a separate communication interface. The communication interface 3208 may allow the pre-lithiation module 3104 to communicate directly with the central controller 3004 or may allow the pre-lithiation module 3104 to communicate indirectly with the central controller, for example, via the formation cluster controller 3110. The communication interface 3208 may be any wired or wireless communication interface that allows the controller to communicate with the communication central controller 3004 directly or over a network. The wireless communication interface 3208 may include a radio frequency (RF) transceiver, a Bluetooth adapter, a Wi-Fi transceiver, a ZigBee transceiver, an infrared (IR) transceiver, and / or any other device and communication protocol connection for wireless communication. (Bluetooth is a registered trademark of the Bluetooth Special Interest Group, Kirkland, Washington, and ZigBee is a registered trademark of the ZigBee Alliance, San Ramon, California.) The wired communications interface 3208 can use any suitable wired communications protocol for direct communications, including, but not limited to, USB, RS232, I2C, SPI, analog, and proprietary I / O protocols. In some embodiments, the wired communications interface 3108 includes a wired network adapter that allows the controller to be coupled to a network, such as the Internet, a local area network (LAN), a wide area network (WAN), a mesh network, and / or any other network for communicating with remote devices and systems over the network.

[0190] 33 is a simplified circuit diagram of an exemplary embodiment of a switched capacitor circuit 3200 connected to a secondary battery 100. The switched capacitor circuit includes a microcontroller 3300, a storage capacitor 3302, a discharge resistor 3304, a first switch 3306, and a second switch 3308.

[0191] Microcontroller 3300 controls the switched capacitor circuit according to a control algorithm stored in its memory. In an exemplary embodiment, microcontroller 3300 is also pre-lithiation module controller 3202. In other embodiments, pre-lithiation module controller 3202 is separate from microcontroller 3300. In an exemplary embodiment, the microcontroller is a PIC 16F15323 microcontroller from Microchip Technology Inc. of Chandler, Arizona, USA. In other embodiments, any other suitable microcontroller may be used. In this embodiment, microcontroller 502 is powered by power supply 3008 via PSU 3113.

[0192] The microcontroller 3300 controls the pre-lithiation of the secondary battery 100 by selectively conducting current through the auxiliary pole 502 by controlling the first switch 3306 and the second switch 3308. The first switch 3306 is an N-channel enhancement mode MOSFET and the second switch 3308 is a P-channel enhancement mode MOSFET. Other embodiments may use any other suitable switches. By closing the first switch 3306 and opening the second switch 3304, the microcontroller 3300 forms a first current path from the negative bus bar 112 of the secondary battery 100 through the first switch 3306 to the auxiliary pole. The first current path includes a storage capacitor 3302. When a current flows through the first current path, lithium diffuses from the auxiliary pole 502 to the electrode active material layer of the battery assembly and energy is stored in the storage capacitor. The microcontroller 3300 then closes the second switch 3308 and opens the first switch 3306 to establish a second current path. The second current path includes a storage capacitor 3302, a discharge resistor, and a second switch 3308. As current flows through the second current path, the energy stored in the capacitor 3302 is discharged through the discharge resistor 3304 and released as heat.

[0193] In an exemplary embodiment, lithium migrates from the auxiliary electrode 502 to the positive electrode active material layer. In other embodiments, the diffusion is to the negative electrode active material layer by connecting the switched capacitor circuit 3200 such that the first current loop includes the anode bus bar 110 instead of the cathode bus bar 112. In yet other embodiments, the switched capacitor circuit 3200 may be duplicated such that there are two first current loops, one including the anode bus bar 110 and the other including the cathode bus bar 112. Such an embodiment allows a single pre-lithiation module 3104 to migrate lithium from the auxiliary electrode 502 to the positive and negative electrode active material layers of the secondary battery without having to stop the formation process to reconfigure the connections to the secondary battery 100 and the auxiliary electrode, and without having to use two separate pre-lithiation modules.

[0194] Pre-lithiation of the secondary battery 100 using the switched capacitor circuit 3200 generally draws charge from one small packet of the battery assembly at a time at a high rate. Thus, the average current is equal to the packet charge / discharge frequency multiplied by the packet size in coulombs, as shown by:

number

number

[0195] To control the switched capacitor circuit 3200, the microcontroller 3300 uses a pulse frequency modulated (PFM) control signal to the first switch 3306 and the second switch 3308. PFM is described by pulses with a fixed width (i.e., each pulse is at a fixed length of time) with a variable time between the pulses. The time between the pulses is varied to provide different frequencies for charge transfer. The faster the packets move (i.e., the shorter and higher the frequency of the fixed width pulses), the higher the current conducted through the auxiliary pole 502. Conversely, the lower the frequency of the pulses (i.e., the longer the time between the pulses), the lower the current conducted through the auxiliary pole. The upper limit of the current conducted through the auxiliary pole is determined by the settling time of the RC circuit element of the switched capacitor circuit 3200. Thus, by varying the frequency of the control pulses to the switches 33060 and 3304, the microcontroller 3300 can control the current flowing through the auxiliary pole 502. In another embodiment, the microcontroller 3300 uses pulse width modulated (PWM) control signals to the first switch 3306 and the second switch 3308. With PWM control, pulses occur at a fixed frequency, but the length of each pulse can be varied to control the amount of charge moved, thereby controlling the amount of current.

[0196] FIG. 34A is a graph of a series of PFM control pulses applied to switches 3306 and 3308 as a function of time. As can be seen, in a first portion 3400 of the series of pulses, fixed width pulses are applied at a higher frequency than in a second portion 3402 of the series of pulses. FIG. 34B is a graph of the resulting current through auxiliary pole 502 in response to the control pulses shown in FIG. 34A as a function of time. The current increases in a sawtooth pattern during the first portion 3400 to a first maximum current 3404. When the frequency of the pulses is reduced in the second portion 3402, the current through auxiliary pole 502 decreases to a second maximum current 3406 that is lower than the first maximum current.

[0197] 35 is a circuit diagram of an exemplary implementation of a switched-capacitor circuit 3200 connected to a secondary battery 100. Like components share reference numbers with their corresponding components in FIG. 33. In this embodiment, the microcontroller 3300 is powered by the secondary battery 100 rather than the PSU 3113. The microcontroller 3300 presents a small leakage on the battery assembly, generally in the range of 50 nA to 100 nA, in most situations except when it is in an active state.

[0198] During the pre-lithiation process, the microcontroller 3300 detects the voltage at the negative electrode of the secondary battery 100 and the voltage V at the auxiliary electrode 502. L Monitor the cathode voltage V c To measure V, pin RC3 of the microcontroller 3300 is driven low with respect to the positive pole of the battery assembly, which is considered the reference point for this circuit. This creates a voltage divider, which measures the voltage V y is read out on pin RA0 of the microcontroller 3300. Then, the cathode voltage V c is calculated by the microcontroller 3300 as follows:

number

number

[0199] When measuring the voltage, the microcontroller 3300 may use filtering to increase the stability of the measurement. For example, the microcontroller 3300 may use decimation, non-linear IIR filtering, or some combination of such signal processing to improve measurement stability. Filtering can improve resolution and reduce noise before the data is consumed by the management functions of the microcontroller 3300. This provides a relatively clean decision-making regardless of any external factory noise that may otherwise affect the measurement. Because pre-lithiation is a relatively slow process (often requiring tens of hours), significant signal processing can be used without much concern regarding time.

[0200] 36A-36C are graphs of exemplary pre-lithiation profiles used by the microcontroller 3300 to perform pre-lithiation of the secondary battery 100. FIG. 36A is a graph showing the buffer current (i.e., the current through the auxiliary pole 502) as a function of the voltage difference in millivolts (mV) between the negative pole of the secondary battery 100 and the auxiliary pole. FIG. 36B is a graph showing the period of the pulses as a function of the voltage difference in mV between the negative pole of the secondary battery 100 and the auxiliary pole. FIG. 36C is a graph showing the number of pulses as a function of the voltage difference in mV between the negative pole of the secondary battery 100 and the auxiliary pole. Of course, different profiles may be used for battery assemblies 100 having different capacities and / or different upper charging voltage limits.

[0201] The pre-lithiation profiles shown in Figures 36A-36C were used in conjunction with the embodiment of the switched capacitor circuit 3200 shown in Figure 33 to pre-lithiate a secondary battery 100. The results of this process are shown in Figures 37A and 37B. Figure 37A is a graph of the cathode-to-anode voltage 3700 and the cathode-to-auxiliary voltage 3702 as a function of time. Figure 37B is a graph of the buffer current as a function of time.

[0202] The embodiments of the present disclosure utilize an auxiliary electrode to transfer or buffer carrier ions to the secondary battery during or after the initial formation of the secondary battery. Transferring carrier ions to the secondary battery (also referred to as pre-lithiation or buffering) provides the technical advantage of mitigating carrier ion losses during formation, for example, by the SEI, thereby improving the capacity of the secondary battery. Furthermore, transferring or buffering carrier ions to the secondary battery provides the negative electrode of the secondary battery with additional carrier ions in excess of the positive electrode coulombic capacity of the secondary battery, thereby providing a reservoir of additional carrier ions over the cycle life of the secondary battery, further mitigating carrier ion losses during cycling due to side reactions that remove carrier ions from availability during cycling. The result of the additional carrier ions in the negative electrode provides the further technical advantage of reducing the amount of capacity loss in the secondary battery from one discharge-charge cycle to the next, thereby improving the overall capacity of the secondary battery during cycle life.

[0203] The following embodiments are provided to illustrate various aspects of the present disclosure. The following embodiments are not intended to be limiting, and thus the present disclosure further supports other aspects and / or embodiments not specifically provided below.

[0204] Embodiment 1. A cell formation system for lithium-based secondary batteries, each of which includes a bilayer assembly, an electrode bus bar, a counter electrode bus bar, an auxiliary electrode, an enclosure surrounding the bilayer assembly, the electrode bus bar, the counter electrode bus bar, and the auxiliary electrode, a first terminal electrically connected to the electrode bus bar and extending from the enclosure, a second terminal electrically connected to the counter electrode bus bar and extending from the enclosure, and a conductive tab electrically connected to the auxiliary electrode and extending from the enclosure. each bilayer of the population of bilayers comprises an electrode structure, a separator structure, and a counter electrode structure, the electrode structure of each member of the bilayer population comprises an electrode current collector and an electrode active material layer, the counter electrode structure of each member of the bilayer population comprises a counter electrode current collector and a counter electrode active material layer, and the cell formation system is a battery tray having a population of side surfaces and a base connected to the population of side surfaces, the battery tray including a population of battery slots above the base, each battery slot of the population of battery slots having a first terminal, a second terminal 13. A cell formation system comprising: a battery tray configured to hold one lithium-based secondary battery with the conductive tab extending through the battery tray base to a position accessible from an underside of the battery tray base; and a forming base configured to attach to the battery tray from an underside of the battery tray base, the forming base including a population of connector groups and a population of pre-lithiated modules, each connector group of the population of connector groups configured to make electrical contact with the conductive tab and at least one of a first terminal and a second terminal of a different one of the lithium-based secondary batteries in the battery tray, each pre-lithiated module of the population of pre-lithiated modules electrically connected to the at least one connector group, and each pre-lithiated module configured to diffuse lithium to an electrode active material of a lithium-based secondary battery connected to the connector group to which the pre-lithiated module is electrically connected.

[0205] Embodiment 2. The cell formation system of embodiment 1, wherein the formation base comprises a population of supports, and the population of pre-lithiated modules are formed on the population of supports, and each support of the population of supports is electrically connected to at least one connector group.

[0206] Embodiment 3. The cell formation system of embodiment 2, wherein each support of the population of supports comprises two or more pre-lithiated modules.

[0207] Embodiment 4. The cell formation system of embodiment 2, wherein each support of the population of supports comprises one pre-lithiated module.

[0208] Embodiment 5. A cell formation system according to any one of embodiments 1 to 4, wherein each pre-lithiated module comprises a switched capacitor circuit.

[0209] Embodiment 6. A cell formation system as described in embodiment 5, wherein each pre-lithiation module includes a pre-lithiation module controller connected to its switched capacitor circuit, each pre-lithiation module controller including a processor and a memory, the memory storing instructions for programming the pre-lithiation module controller to operate the switched capacitor circuit to selectively conduct current for diffusing lithium into an electrode active material layer of a lithium-based secondary battery connected to a connector group to which the pre-lithiation module is electrically connected.

[0210] Embodiment 7. A cell formation system as described in embodiment 5, wherein the formation base comprises a pre-lithiation module controller connected to two or more switched capacitor circuits, the pre-lithiation module controller including a processor and a memory, the memory storing instructions for programming the pre-lithiation module controller to operate the switched capacitor circuits to each selectively conduct an electric current for diffusing lithium into an electrode active material layer of a lithium-based secondary battery connected to a connector group to which the pre-lithiation module is electrically connected.

[0211] Embodiment 8. A cell formation system described in any one of embodiments 1 to 7, wherein the battery tray includes a first assembly connector and the forming base includes a second assembly connector configured to mate and engage with the first assembly connector to mechanically connect the battery tray to the forming base.

[0212] Embodiment 9. A cell formation system as described in embodiment 8, wherein the first assembly connector comprises a rectangular slot in the base of the battery tray and the second assembly connector comprises a rotatable rectangular bar extending from the forming base and having a rectangular dimension smaller than the rectangular slot in the base of the battery tray.

[0213] Embodiment 10. A cell formation system as described in any one of embodiments 1 to 9, further comprising a charging station including a charging module configured to charge the lithium-based secondary batteries in the battery tray, the charging station configured to receive a battery tray without a forming base attached, the charging station including a population of charging connector groups electrically connected to the charging module, each charging connector group of the population of connector groups configured to make electrical contact with a first terminal and a second terminal of a different one of the lithium-based secondary batteries in the battery tray.

[0214] Embodiment 11. A cell formation system as described in any one of embodiments 1 to 9, further comprising a charging station including a population of charging modules configured to charge the lithium-based secondary batteries in the battery tray, the charging station configured to receive a battery tray without a forming base attached, the charging station including a population of charging connector groups each electrically connected to a different charging module, each charging connector group of the population of connector groups configured to make electrical contact with a first terminal and a second terminal of a different one of the lithium-based secondary batteries in the battery tray.

[0215] Embodiment 12. A cell formation system according to any one of embodiments 1 to 11, wherein the group of battery slots consists of 120 battery slots.

[0216] Embodiment 13. A method of a cell formation system for a lithium-based secondary battery, wherein each lithium-based secondary battery comprises a bilayer assembly, an electrode bus bar, a counter electrode bus bar, an auxiliary electrode, an enclosure surrounding the bilayer assembly, the electrode bus bar, the counter electrode bus bar, and the auxiliary electrode, a first terminal electrically connected to the electrode bus bar and extending from the enclosure, a second terminal electrically connected to the counter electrode bus bar and extending from the enclosure, and a conductive tab electrically connected to the auxiliary electrode and extending from the enclosure, wherein each of the bilayer assembly and the electrode bus bar is electrically connected to the counter electrode bus bar. each of the bilayers comprises an electrode structure, a separator structure, and a counter electrode structure, the electrode structure of each member of the bilayer population comprises an electrode current collector and an electrode active material layer, and the counter electrode structure of each member of the bilayer population comprises a counter electrode current collector and a counter electrode active material layer, the method comprising: (i) loading a population of lithium-based secondary batteries into a battery tray having a population of side surfaces and a base connected to the population of side surfaces, the battery tray including a population of battery slots above the base, each battery slot of the population of battery slots having a first end and a second end; (ii) mounting a forming base on the battery tray from beneath the battery tray base to form a formed assembly, the forming base including a population of connector groups and a population of pre-lithiated modules, each connector group of the population of connector groups configured to make electrical contact with the conductive tab and at least one of the first terminal and the second terminal of a different one of the lithium-based secondary batteries in the battery tray, each pre-lithiated module of the population of pre-lithiated modules electrically connected to the at least one connector group, each pre-lithiated module configured to diffuse lithium into an electrode active material of a lithium-based secondary battery connected to the connector group to which the pre-lithiated module is electrically connected;(iii) positioning the forming assembly in a forming station; (iv) buffering the population of lithium-based secondary batteries in the forming assembly using a pre-lithiation module; (v) removing the forming base from the battery tray; and (vi) performing additional processes on the population of lithium-based secondary batteries in the battery tray.

[0217] Embodiment 14. The method of embodiment 1, further comprising: (vii) loading an additional population of lithium-based secondary batteries into an additional battery tray; (viii) attaching a forming base to the additional battery tray to form an additional forming assembly; (ix) positioning the additional forming assembly within the forming station; (x) buffering the population of lithium-based secondary batteries in the additional forming assembly using a pre-lithiation module; and (xi) removing the forming base from the additional battery tray.

[0218] Embodiment 15. The method of embodiment 13 or embodiment 14, further comprising, after (i) and before (ii), (i') positioning the battery tray in a charging station, (i") charging the population of lithium-based secondary batteries in the battery tray, and (i'') removing the battery tray from the charging station.

[0219] Embodiment 16. The method of any one of embodiments 13 to 15, wherein (i) loading the population of lithium-based secondary batteries into the battery tray includes loading 120 lithium-based secondary batteries into the battery tray.

[0220] Embodiment 17. A method according to any one of embodiments 13 to 16, wherein the battery tray includes a first assembly connector and the forming base includes a second assembly connector configured to mate and engage with the first assembly connector to mechanically connect the battery tray to the forming base, and (ii) attaching the forming base to the battery tray from an underside of the battery tray's base to form a forming assembly includes positioning the battery tray on top of the forming base and actuating the second assembly connector to engage the second assembly connector with the first assembly connector.

[0221] Embodiment 18. A cell formation system for a lithium-based secondary battery, each lithium-based secondary battery comprising: a collection of bilayers; an electrode bus bar; a counter electrode bus bar; an auxiliary electrode; an enclosure surrounding the collection of bilayers, the electrode bus bar, the counter electrode bus bar, and the auxiliary electrode; a first terminal electrically connected to the electrode bus bar and extending from the enclosure; a second terminal electrically connected to the counter electrode bus bar and extending from the enclosure; and a conductive tab electrically connected to the auxiliary electrode and extending from the enclosure, each bilayer of the collection of bilayers comprising an electrode bus bar; the electrode structure of each member of the bilayer population comprises an electrode current collector and an electrode active material layer, the counter electrode structure of each member of the bilayer population comprises a counter electrode current collector and a counter electrode active material layer, and the cell formation system includes a battery tray having a population of side surfaces and a base connected to the population of side surfaces, the battery tray including a population of battery slots above the base, each battery slot of the population of battery slots having a first terminal, a second terminal, and a conductive tab extending through the base of the battery tray to an underside of the base of the battery tray. a battery tray configured to hold one lithium-based secondary battery in a state in which the battery tray extends to an accessible position; a forming base configured to be attached to the battery tray from an underside of the battery tray base, the forming base including a population of connector groups, each connector group of the population of connector groups configured to make electrical contact with the conductive tab and at least one of the first terminal and the second terminal of a different one of the lithium-based secondary batteries in the battery tray; and a population of forming clusters, each forming cluster including: a charging module connected to one of the connector groups and configured to charge the lithium-based secondary battery connected to the connector group; a pre-lithiation module connected to one of the connector groups and configured to diffuse lithium into an electrode active material of the lithium-based secondary battery connected to the connector group; and a discharging module connected to one of the connector groups and configured to discharge the lithium-based secondary battery connected to the connector group.a formation base including a population of formation clusters;

[0222] Embodiment 19. A cell formation system as described in embodiment 18, wherein the formation base comprises a population of supports, the population forming cluster is formed on the population of supports, and each support of the population of supports is electrically connected to at least one connector group.

[0223] Embodiment 20. A cell formation system as described in embodiment 19, wherein each support of the population of supports comprises more than the forming cluster.

[0224] Embodiment 21. A cell formation system as described in embodiment 19, wherein each support of the population of supports comprises one formation cluster.

[0225] Embodiment 22. A cell formation system described in any one of embodiments 18 to 21, wherein each pre-lithiation module comprises a switched capacitor circuit.

[0226] Embodiment 23. A cell formation system as described in embodiment 22, wherein each pre-lithiation module includes a pre-lithiation module controller connected to its switched capacitor circuit, each pre-lithiation module controller including a processor and a memory, the memory storing instructions for programming the pre-lithiation module controller to operate the switched capacitor circuit to selectively conduct current for diffusing lithium into an electrode active material layer of a lithium-based secondary battery connected to a connector group to which the pre-lithiation module is electrically connected.

[0227] Embodiment 24. A cell formation system as described in embodiment 22, wherein the formation base comprises a pre-lithiation module controller connected to two or more switched capacitor circuits, the pre-lithiation module controller including a processor and a memory, the memory storing instructions for programming the pre-lithiation module controller to operate the switched capacitor circuits to each selectively conduct an electric current for diffusing lithium into an electrode active material layer of a lithium-based secondary battery connected to a connector group to which the pre-lithiation module is electrically connected.

[0228] Embodiment 25. A cell formation system described in any one of embodiments 18 to 24, wherein the battery tray includes a first assembly connector and the forming base includes a second assembly connector configured to mate and engage with the first assembly connector to mechanically connect the battery tray to the forming base.

[0229] Embodiment 26. A cell formation system as described in embodiment 25, wherein the first assembly connector has a rectangular slot in the base of the battery tray and the second assembly connector has a rotatable rectangular bar extending from the forming base and having a rectangular dimension smaller than the rectangular slot in the base of the battery tray.

[0230] Embodiment 27. A cell formation system described in any one of embodiments 18 to 26, wherein the group of battery slots consists of 120 battery slots.

[0231] Embodiment 28. A cell formation system described in any one of embodiments 18 to 27, wherein the group of battery slots is integrally formed within the battery tray.

[0232] Embodiment 29. A cell formation system described in any one of embodiments 18 to 27, wherein the group of battery slots is removably attached to the battery tray.

[0233] Embodiment 30. A method of a cell formation system for lithium-based secondary batteries, each lithium-based secondary battery comprising: a collection of bilayers; an electrode bus bar; a counter electrode bus bar; an auxiliary electrode; an enclosure surrounding the collection of bilayers, the electrode bus bar, the counter electrode bus bar, and the auxiliary electrode; a first terminal electrically connected to the electrode bus bar and extending from the enclosure; a second terminal electrically connected to the counter electrode bus bar and extending from the enclosure; and a conductive tab electrically connected to the auxiliary electrode and extending from the enclosure; each bilayer of the bilayers comprises an electrode structure, a separator structure, and a counter electrode structure, the electrode structure of each member of the bilayer population comprises an electrode current collector and an electrode active material layer, and the counter electrode structure of each member of the bilayer population comprises a counter electrode current collector and a counter electrode active material layer, the method comprising: (i) loading, at a first location, a population of battery trays, each having a population of lithium-based secondary batteries, each battery tray being configured with a first terminal, a second terminal, and a conductive tab extending through the battery tray to a position accessible from an underside of the battery tray; (ii) transporting the population of battery trays to a second location having at least one charging station; (iii) positioning the battery trays in the charging station; (iv) charging the population of lithium-based secondary batteries in the battery trays at the charging station; (v) removing the battery trays from the charging station; and (vi) attaching a population of forming bases to the battery trays, each battery tray having a different forming base attached thereto, each forming base including a population of connector groups and a population of pre-lithiated modules, each connector group of the population of connector groups configured to make electrical contact with the conductive tabs and at least one of the first terminal and the second terminal of a different one of the lithium-based secondary batteries in the battery trays, each pre-lithiated module of the population of pre-lithiated modules being electrically connected to the at least one connector group, each pre-lithiated module being configured to(vii) transporting the battery tray with the attached forming base to a third location having at least one forming station, (viii) positioning the battery tray with the attached forming base in the forming station, (ix) buffering the population of lithium-based secondary batteries in the battery tray using the pre-lithiation module in the forming base, (x) removing the battery tray with the attached forming base from the forming station, (xi) removing the forming base from the battery tray, (xii) transporting the battery tray to a fourth location, and (xiii) performing additional processes on the population of lithium-based secondary batteries in the battery tray at the fourth location.

[0234] Embodiment 31. The method of embodiment 30, further comprising: (xiv) loading a population of additional battery trays at a first location, each having a population of additional lithium-based secondary batteries; (xv) transporting the population of additional battery trays to a second location; (xvi) positioning the additional battery trays in a charging station; (xvii) charging the population of additional lithium-based secondary batteries in the additional battery trays at the charging station; (xviii) removing the additional battery trays from the charging station; (xix) attaching forming bases to the population of additional battery trays; and repeating (xv)(vii)-(x) for the additional battery trays having attached forming bases.

[0235] Embodiment 32. A cell formation system described in any one of embodiments 1 to 12, wherein the group of battery slots is integrally formed within the battery tray.

[0236] Embodiment 33. A cell formation system described in any one of embodiments 1 to 12, wherein the group of battery slots is removably attached to the battery tray.

[0237] This written specification uses examples to disclose the invention, including the best mode, and also enables any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal words of the claims, or if they include equivalent structural elements with differences that do not differ insubstantially from the literal words of the claims.

Claims

1. A system for forming cells of a plurality of batteries, the system comprising: a tray having a base connected to a side extending from the base in an upward direction, the base having an upper side and a lower side opposite the upper side, the lower side being in a downward direction relative to the upper side and the downward direction being opposite the upward direction, the tray including a plurality of slots adjacent the upper side, each of the plurality of slots holding a battery with a first terminal and a second terminal extending through the base of the tray to a position in the downward direction, the first terminal and the second terminal being accessible from the underside, each battery of the plurality of batteries having the first terminal electrically coupled to at least one electrode and the second terminal electrically coupled to at least one counter electrode, the tray being configured to accommodate the plurality of batteries, a forming base configured to attach to the tray at its underside, the forming base including a plurality of connector groups and a plurality of pre-lithiated modules, each connector group configured to electrically connect with at least one of (i) the first terminal of the first battery and (ii) the second terminal of the second battery, each pre-lithiated module of the plurality of pre-lithiated modules electrically connected to at least one of the plurality of connector groups, and each pre-lithiated module configured to allow diffusion of lithium into an electrode active material of at least one electrode of the battery connected to the connector group to which the pre-lithiated module is electrically connected; A system comprising:

2. The system described in claim 1, wherein: (A) the forming base comprises a plurality of supports; (B) the plurality of pre-lithiated modules are formed on the plurality of supports; and (C) each support of the plurality of supports is electrically connected to at least one of the plurality of connector groups.

3. The system described in claim 2, wherein each support of the plurality of supports includes one pre-lithiated module.

4. The system described in claim 2, wherein each support of the plurality of supports includes one or more pre-lithiated modules.

5. The system described in claim 1, wherein each pre-lithiated module comprises a switched capacitor circuit.

6. The system of claim 1, wherein the tray includes a first assembly connector and the forming base includes a second assembly connector configured to mate and engage with the first assembly connector to mechanically connect the tray to the forming base.

7. The system described in claim 6, wherein the second assembly connector comprises a rotatable bar extending from the forming base.

8. The system described in claim 6, wherein the first assembly connector has a slot in the base of the tray, and the second assembly connector has a rotatable bar extending from the forming base and having dimensions smaller than the slot in the base of the tray.

9. The system described in claim 6, wherein the first assembly connector has a rectangular slot in the base of the tray, and the second assembly connector has a rotatable rectangular bar extending from the formed base and having rectangular dimensions smaller than the rectangular slot in the base of the tray.

10. The system described in claim 1, further comprising a charging station including a charging module configured to charge the plurality of batteries in the tray, the charging station configured to accept the tray without the forming base attached, the charging station including a plurality of charging connector groups electrically connected to the charging module, each charging connector group of the plurality of charging connector groups configured to be in electrical contact with the first terminal of the first battery and the second terminal of the second battery.

11. The system of claim 1, further comprising a charging station including a charging module configured to charge the plurality of batteries in the tray, the charging station configured to accept the tray without the forming base attached, the charging station including a plurality of charging connector groups, each of the plurality of charging connector groups electrically connected to a different charging module, and each charging connector group of the plurality of charging connector groups configured to be in electrical contact with the first terminal of the first battery and the second terminal of the second battery.

12. The system described in claim 1, further comprising a discharge module configured to connect to one of the plurality of connector groups, the discharge module configured to discharge a battery connected to the connector group.

13. The system described in claim 1, wherein the plurality of slots are integrally formed with the tray.

14. The system described in claim 1, wherein the plurality of slots are removably attached to the tray.

15. The system described in claim 1, wherein the battery is electrically coupled to an auxiliary electrode.

16. The system described in claim 15, wherein the auxiliary poles are configured to be simultaneously coupled to opposite sides of the battery.

17. The system described in claim 15, wherein the auxiliary electrode is configured to supply carrier ions during and / or after formation of the battery by at least partly using the system, and the carrier ions include lithium.

18. The system of claim 15, wherein the system is configured to electrochemically couple the battery to an auxiliary electrode, the auxiliary electrode configured to reduce initial loss of carrier ions in the battery during initial formation, the carrier ions comprising lithium.

19. The system of claim 15, wherein the system is configured to electrochemically couple the battery to an auxiliary electrode, the auxiliary electrode being configured to increase the capacity of the battery after formation compared to the capacity before formation.

20. The system described in claim 1, wherein the at least one electrode and the at least one counter electrode of the battery are held by a constraint portion having a plurality of perforations, the constraint portion being positioned on a surface of the battery having the largest surface area, and the plurality of batteries includes the battery.

21. The system described in Claim 20, wherein the multiple perforations are evenly spaced along the constraint portion.

22. The system described in claim 20, wherein each of the plurality of perforations has a first semicircle and a second semicircle opposite the first semicircle.

23. The system described in claim 20, wherein the plurality of perforations are configured to facilitate flow of electrolyte solution through the plurality of perforations into the battery.

24. The system of claim 20, wherein the constraint portion includes a polymer.

25. The system of claim 1, wherein the electrode active material comprises silicon.

26. The system of claim 1, wherein the electrode active material comprises a silicon-carbon (Si / C) composite material.

27. ​​The system described in claim 1, wherein the electrode active material includes a composite material.

28. The system of claim 1, wherein the electrode active material comprises hard carbon.

29. The system described in claim 1, wherein the electrode active material comprises soft carbon.

30. The system of claim 1, wherein the electrode active material comprises nanotubes.

31. The system described in claim 1, wherein the electrode active material includes an active material layer.

32. The system of claim 1, wherein the electrode active material comprises a material layer that is macroporous, microporous, mesoporous, or a combination thereof.

33. The system described in claim 1, wherein the electrode active material includes openings through which carrier ions can enter and exit, and the carrier ions are lithium.

34. A method for forming cells of a plurality of batteries, the method comprising: (a) providing a system described in any one of claims 1 to 33; and (b) using the system to form cells of the plurality of batteries.

35. Non-transitory computer-readable program instructions that, when read by one or more processors operably coupled to a system described in any one of claims 1 to 33, cause the one or more processors to perform one or more operations for forming cells of the plurality of batteries.

36. An apparatus for forming cells of a plurality of batteries, comprising a plurality of controllers configured to be operatively coupled to a system described in any one of claims 1 to 33, wherein the plurality of controllers instruct the system to perform one or more operations for forming cells of the plurality of batteries.

37. The apparatus described in claim 36, wherein the plurality of controllers includes a central controller, a forming cluster controller configured to instruct the plurality of modules, and a module controller configured to control tasks of one or more modules of the plurality of modules.

38. The apparatus described in claim 36, wherein each pre-lithiation module includes a pre-lithiation module control system connected to a switched capacitor circuit, the pre-lithiation module control system being configured to instruct the switched capacitor circuit to selectively conduct current to diffuse lithium into the electrode active material of the battery connected to the connector group to which the pre-lithiation module is electrically connected, and the plurality of controllers include the pre-lithiation module control system.

39. The apparatus described in claim 36, wherein the forming base includes a pre-lithiation module control system connected to a plurality of switched capacitor circuits, the pre-lithiation module control system configured to operate the switched capacitor circuits to each selectively conduct current for diffusing lithium into the electrode active material of the battery connected to the connector group to which the pre-lithiation module is electrically connected, and the plurality of controllers include the pre-lithiation module control system.

40. A system for forming cells of a plurality of batteries, the system comprising an auxiliary electrode configured to contact at least one side of a unit cell stack of one of the plurality of batteries, the at least one side being a type having the largest surface area among the side types of the unit cell stack, the unit cell stack including one or more unit cells, one unit cell of the one or more unit cells including an electrode and an opposing counter electrode stacked along an axis, the auxiliary electrode configured to contact the side to enable pre-loading of charge carriers in an electrode active material of an electrode of the battery, the battery and the auxiliary electrode being positioned in a tray of the system, the tray being configured to enable the system to be electrically connected to a power source.

41. A system for forming cells of a plurality of batteries, the system comprising a pouch containing an auxiliary electrode and a battery, the auxiliary electrode configured to contact at least one side of a unit cell stack of the battery, the unit cell stack including one or more unit cells, one unit cell of the one or more unit cells including an electrode and an opposing counter electrode stacked along an axis, the auxiliary electrode configured to contact the side to enable pre-loading of charge carriers in an electrode active material of the electrode of the battery, the pouch sealed to enable electrical connection using a conductive tab extending from the interior of the pouch to the exterior of the pouch, the battery and the auxiliary electrode positioned in a tray of the system, the tray configured to enable the system to be electrically connected to a power source.

42. A system for forming cells of a plurality of batteries, the system including a constraint system having a plurality of perforations configured to facilitate the flow of electrolyte through the plurality of perforations into the plurality of batteries, the electrolyte acting as a medium for conducting carrier ions through the plurality of perforations during formation of the batteries, allowing pre-loading of charge carriers in electrode active material of electrodes of the batteries, the batteries and the auxiliary electrodes being positioned within a tray of the system, the tray configured to allow the system to be electrically connected to a power source.

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