Multi-layer electrodes with current-optimized electronic resistances and batteries with the same features

Abstract

Lithium battery cell (10) comprising: an electrolyte (17); an anode (11) disposed within the electrolyte (17) and including a current collector (12) having the following: a length (L), the length (L) defining a first end (31) and a second end (32), a width (W), a host material of the anodes (11) disposed on the current collector (12) of the anode (11) between the first end (31) and the second end (32), a first tab (33) extending from the first end (31), and a second tab (34) extending from the second end (32); and a cathode (14) disposed within the electrolyte (17) and including a current collector (15) having: a length (L), the length (L) defining a first end (31) and a second end (32), a width (W), an active material of the cathode (14) disposed on the current collector (15) of the cathode (14) between the first end (31) and the second end (32), a first tab (33) extending from the first end (31), and a second tab (34) extending from the second end (32); characterized in that the current collector (12) of the anode (11) has a first anode electronic resistor (35) extending longitudinally inward from the first end (31), and the current collector (15) of the cathode (14) has a first cathode electronic resistor (35) extending longitudinally inward from the first end (31); wherein one or more of the anodes (11) and cathodes (14) are thicker near the middle of the length.

Description

[0001] The present invention relates to a lithium battery cell according to the preamble of claim 1, as is essentially known from US 8 248 756 B2.

[0002] Furthermore, the invention relates to battery packs with a special electrode geometry.

[0003] From US 2015 0 243 962 A1 it is known to form the electrodes of a battery cell with slots in order to give the electrode more flexibility.

[0004] Further prior art can be found in WO 2007 063 877 A1. INTRODUCTION

[0005] Lithium-ion batteries describe a class of rechargeable batteries in which lithium ions move between a negative electrode (i.e., anode) and the positive electrode (i.e., cathode). Liquid and polymer electrolytes can facilitate the movement of lithium ions between the anode and cathode. Lithium-ion batteries are becoming increasingly popular for use in defense, automotive, and aerospace applications due to their high energy density and ability to undergo consecutive charge and discharge cycles. SUMMARY

[0006] A lithium battery cell is provided which is characterized by the features of claim 1.

[0007] The first tab of the cathode may be asymmetrical to the second tab of the cathode, and / or the first tab of the anode may be asymmetrical to the second tab of the anode. The first anode electronic resistor may be located closer to the center of the width of the first end of the anode than the first end of the anode, and / or the first cathode electronic resistor may be located closer to the center of the width of the first end of the cathode than the first tab of the cathode. The first anode electronic resistor may be adjacent to the first tab of the anode, and / or the first cathode electronic resistor may be adjacent to the first tab of the cathode. The first anode electronic resistor and / or the first cathode electronic resistor may include a slot in the anode current collector and the cathode current collector, respectively. The first anode electronic resistor and / or the first cathode electronic resistor may include a region with substantially no anode or cathode current.Cathode host material. The first anode electronic resistor and / or the first cathode electronic resistor can be formed via laser ablation or metal blade notches of the anode and cathode host materials, respectively. The anode and cathode can be stacked such that their respective length-width planes are substantially planar with the first end of the anode near the first end of the cathode, and the first anode electronic resistor can be located between the first tab of the anode and the first tab of the cathode, respectively, and / or the first cathode electronic resistor can be located between the first tab of the anode and the first tab of the cathode, respectively. The first tab of the cathode can be symmetrical to the second tab of the cathode, and / or the first tab of the anode can be symmetrical to the second tab of the anode.

[0008] Furthermore, according to the invention, a battery pack is presented which is characterized by the features of claim 2 or those of claim 3.

[0009] The anodes and cathodes may be stacked such that their respective length-width planes are substantially flat. Each of the anode electronic resistors and the second anode electronic resistor may have a length that is less than half the anode length, and each of the first cathode electronic resistors and the second cathode electronic resistors may have a length that is less than half the cathode length. Each of the first anode electronic resistors, the second anode electronic resistors, the first cathode electronic resistors, and the second cathode electronic resistors may be a slot. One or more of the anodes and the cathodes may be thicker at the center of their longitudinal center. The battery pack may be a lithium battery pack. The battery pack may be a power source for an electric or hybrid vehicle.Each of the anodes may have an aspect ratio of at least 2 and the cathode may have an aspect ratio of at least 2.

[0010] Further purposes, advantages and novel features of the embodiments will become apparent from the following detailed description of the embodiments and the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 illustrates a lithium battery cell according to one or more embodiments; Fig. 2 illustrates a schematic diagram of a hybrid electric vehicle according to one or more embodiments; Fig. 3A is a plan view of an electrode according to one or more embodiments; Fig. 3B illustrates a top view of an electrode according to one or more embodiments; Fig. 4A illustrates a schematic side view of a battery pack according to one or more embodiments; Fig. 4B illustrates a perspective view of a battery separator and a plurality of anodes and a plurality of cathodes according to one or more embodiments; and Fig. 4C illustrates a top view of a battery pack according to one or more embodiments. DETAILED DESCRIPTION

[0011] Fig. 1 illustrates a lithium battery cell 10 comprising a negative electrode (i.e., the anode) 11, a positive electrode (i.e., the cathode) 14, an electrolyte 17 operatively disposed between the anode 11 and the cathode 14, and a separator 18. The anode 11, cathode 14, and electrolyte 17 may be enclosed within container 19, which may be, for example, a hard (e.g., metallic) box or a soft (e.g., polymer) bag. The anode 11 and cathode 14 are located on opposite sides of the separator 18, which may comprise a microporous polymer or other suitable material capable of conducting lithium ions and optionally also electrolytes (i.e., liquid electrolytes). For example, the electrolyte may comprise a polymer or a liquid electrolytic solution.Liquid electrolytes 17 may include, among others, LiPF6, LiBF4, and LiClO4 dissolved in a non-aqueous solvent. Polymer electrolytes 17 may include one or more polymers, such as, among others, polyethylene oxide (PEO) or polyacrylonitrile, or one or more lithium salts, such as, among others, LiPF6, LiBF4, LiClO4, LiSICON, or LiPON. The anode 11 generally includes a current collector 12 and a lithium intercalation host material 13 deposited thereon. The cathode 14 generally includes a current collector 15 and a lithium-based active material 16 deposited thereon. In one example, anode 11 comprises lithium. In one embodiment, anode 11 comprises lithium and cathode 14 comprises sulfur. The active material 16 may store lithium ions, for example, at a higher electrical potential than the intercalation host material 13. The

[0012] The current collectors 12 and 15 associated with the electrodes are connected by an interruptible external circuit that allows the flow of electric current between the electrodes to electrically balance the migration of the lithium ions. Although Fig. 1 illustrates the host material 13 and the active material 16 in a schematic manner for the sake of clarity, the host material 13 and the active material 16 may each comprise an exclusive interface between the anode 11 and the cathode 14 and the electrolyte 17.

[0013] The host material 13 may include any lithium host material that sufficiently supports the intercalation, deintercalation, and alloying of lithium ions while acting as the negative terminal of the lithium-ion battery 10. The host material 13 may also include a polymer binder to structurally hold the lithium host material together. For example, in one embodiment, the host material 13 may include graphite blended with one or more of polyvinyldiene fluoride (PVdF), an ethylene propylene diene monomer (EPDM) rubber, carboxymethoxycellulose (CMC), and styrene, 1,3-butadiene polymer (SBR). Graphite and carbonaceous materials are popular for forming the negative electrode because of their desirable properties for intercalating and deintercalating lithium ions, their relatively non-reactive nature, and their ability to store lithium ions in quantities that result in a relatively high energy density.Other materials may also be used to form the host material 13, including, but not limited to, one or more of lithium titanate, silicon, silicon oxide, tin, and tin oxide. The anode current collector 12 may also include, but is not limited to, copper, aluminum, stainless steel, and other suitable electrically conductive materials known to those skilled in the art. The anode current collector 12 may be treated (e.g., coated) with highly electrically conductive materials. These include, but are not limited to, one or more of conductive carbon black, graphite, carbon nanotubes, carbon nanofibers, graphene, and vapor growth carbon fiber (VGCF).

[0014] The active material 16 may include any lithium-based active material sufficiently capable of undergoing lithium intercalation and deintercalation while serving as the positive terminal of the battery cell 10. The active material 16 may also include a polymer binder to structurally hold the lithium-based active material together. A common class of known materials that can be used to fabricate the active material 16 are layered lithium transition metal oxides.In various embodiments, the active material 16 may, for example, comprise one or more of the following: spinel lithium manganese oxide (LiMn2O4), lithium cobalt oxide (LiCoO2), a nickel manganese cobalt oxide [Li(NixMnYCoz)O2], or a lithium iron polyanion oxide, such as lithium iron phosphate (LiFePO4) or lithium iron fluorophosphate (Li2FePO4F) blended with at least one of the following: polyvinyl diene fluoride (PVdF), an ethylene propylene diene monomer (EPDM) rubber, carboxy methoxycellulose (CMC), and styrene, 1,3-butadiene polymer (SBR). Other lithium-based active materials may also be used. These alternative materials include, but are not limited to, lithium nickel oxide (Li-NiO2), lithium aluminum manganese oxide (LixAlYMn1-yO2), and lithium vanadium oxide (LiV2O5), to name a few.The cathode current collector 15 may comprise aluminum or any other suitable electrically conductive material known to those skilled in the art and may be formed in a foil and grid configuration. The cathode current collector 15 may be treated (e.g., coated) with highly electrically conductive materials. These include, but are not limited to, one or more of conductive carbon black, graphite, carbon nanotubes, carbon nanofibers, graphene, and vapor growth carbon fiber (VGCF).

[0015] Any suitable electrolyte solution capable of conducting lithium ions between the anode 11 and the cathode 14 may be used in the battery cell 10. In one embodiment, the electrolyte solution may be a non-aqueous liquid electrolyte solution comprising a lithium salt dissolved in an organic solvent or a mixture of organic solvents. Those skilled in the art are familiar with the many non-aqueous liquid electrolyte solutions that may be used in the battery cell 10, as well as how to manufacture and purchase them commercially. A non-limiting list of lithium salts that may be dissolved in an organic solvent to form the non-aqueous liquid electrolyte solution includes LiClO4, LiAlCl4, LiIl, LiBr, LiSCN, LiBF4, LiB(C6H5)4, LiAsF6, LiCF3SO3, LiN(CF3SO2)2, LiPF6, and combinations thereof.These and similar lithium salts can be used in a number of organic solvents, for example: cyclic carbonates (ethylene carbonate, propylene carbonate, butylene carbonate), acyclic carbonates (dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate), aliphatic carboxylic acid esters (methyl formate, methyl acetate, methyl propionate), γ-lactones (γ-butyrolactone, γ-valerolactone), chain structure ethers (1,2-dimethoxyethane, 1,2-diethoxyethane, ethoxymethoxyethane), cyclic ethers (tetrahydrofuran, 2-methyltetrahydrofuran) and mixtures of these.

[0016] The microporous, polymeric separator 18, in one embodiment, may comprise a polyolefin. The polyolefin may be a homopolymer (derived from a single monomer component) or a heteropolymer (derived from more than one monomer component), and may be either linear or branched. When a heteropolymer derived from two monomer components is used, the polyolefin may adopt any copolymer chain arrangement, including that of a block copolymer or a random copolymer. The same applies when the polyolefin is a heteropolymer derived from more than two monomer components. In one embodiment, the polyolefin may be polyethylene (PE), polypropylene (PP), or a blend of PE and PP. The separator 18 may, among other things, optionally be coated with materials including one or more of the following: ceramic-like alumina (e.g.,Al2O3) and lithiated zeolite-like oxides. Lithiated zeolite-like oxides can improve the safety and service life of lithium-ion batteries, such as battery cell 10.

[0017] The microporous polymer separator 18 may be a single layer or a multi-layer laminate formed from either a dry or wet process. For example, in one embodiment, a single layer of polyolefin may constitute the entirety of the microporous polymer separator 18. However, as another example, the microporous polymer separator 18 may also be composed of multiple separate layers of the same or a dissimilar polyolefin. The microporous polymer separator 18 may comprise other polymers besides the polyolefin, such as, but not limited to, polyethylene terephthalate (PET), polyvinylidene fluoride (PVdF), and / or a polyamide (nylon).The polyolefin layer and any other polymer layers that may be present may also be included in the microporous polymer separator 18 as a fibrous layer to provide the microporous polymer separator 18 with suitable structural and porosity characteristics. Those skilled in the art are aware not only of the many available polymers and commercially available products from which the microporous polymer separator 18 may be made, but also of the many processes that may be used to manufacture the microporous polymer separator 18.

[0018] The battery cell 10 is generally powered by the reversible flow of lithium ions between the anode 11 and the cathode 14. Lithium ions move from the cathode 14 to the anode 11 during the charging process and from the anode 11 to the cathode 14 during the discharging process. At the beginning of a discharge, the anode 11 contains a high concentration of intercalated lithium ions, while the cathode 14 is more or less depleted. Establishing a closed external circuit between the anode 11 and the cathode 14 causes the intercalated lithium ions to be extracted from the anode 11 under such circumstances. The extracted lithium ions are split into lithium ions and electrons as they leave an intercalation host at the electrode-to-electrolyte interface.The lithium ions are carried through the micropores of the separator 18 from the anode 11 to the cathode 14 through the ionically conductive electrolyte 17, while the electrons are simultaneously transferred through the external circuitry from the anode 11 to the cathode 14 to balance the overall electrochemical cell. The flow of electrons through the external circuitry can be harnessed and fed into a charging device until the level of lithium stored in the negative electrode falls below a minimum level, or when there is no longer a need for energy. The arrows indicate that current is flowing out of the anode 11 and that current is flowing into the cathode 14, which is why the battery cell 10 is shown as being in a charged state.

[0019] The battery cell 10 can be recharged after a partial or full discharge of its available capacity. To recharge or resupply the lithium-ion battery cell, an external power source (not shown) is connected to the positive and negative electrodes to reverse the electrochemical reactions of battery discharge. This means that during charging, the external power source extracts the lithium ions present in the cathode 14 to produce lithium ions and electrons. The lithium ions are carried back through the electrolyte solution by the separator, and the electrons are driven back by the external circuit, both times toward the anode 11. The lithium ions and electrons are finally reunited at the negative electrode, where lithium is again stored for future discharge of the battery cell.

[0020] The lithium-ion battery cell 10, or a battery module or pack comprising a plurality of battery cells 10 connected in series and / or parallel, can be used to reversibly supply current and energy to an associated charging device. Lithium-ion batteries can also be used in various consumer electronic devices (e.g., laptop computers, cameras, and cell phones / smartphones), military electronics (e.g., radios, mine detectors, and thermal weapons), aircraft, and satellites, among others. Lithium-ion batteries, modules, and packs can be integrated into a vehicle, such as a hybrid electric vehicle (HEV), a battery electric vehicle (BEV), a plug-in HEV, or an extended-range electric vehicle (EREV), to generate sufficient current and energy to operate one or more systems of the vehicle.For example, battery cells, modules, and packs can be used in combination with a gasoline or diesel internal combustion engine to power the vehicle (as in hybrid electric vehicles), or can be used alone to power the vehicle (as in battery-powered vehicles).

[0021] Fig. 2 illustrates a schematic diagram of a hybrid electric vehicle 1 including a battery pack 20 and associated components. A battery pack, such as battery pack 20, may include a plurality of battery cells 10. A plurality of battery cells 10 may be connected in parallel to form a group, and a plurality of groups may be connected in series, for example. One skilled in the art will understand that any number of battery cell connection configurations is practical when using the battery cell architectures used herein and will further recognize that vehicle applications are not limited to the described vehicle architecture. Battery pack 20 may provide power to an inverter 2, which converts the direct current (DC) battery voltage to a three-phase alternating current (AC) signal used by a drive motor 3 to propel vehicle 1.A motor 5 can be used to drive a generator 4, which in turn can provide energy to recharge the battery pack 20 via the inverter 2. External (e.g., grid) power can also be used to recharge the battery pack 20 via an additional circuit (not shown). The motor 5 can comprise, for example, a gasoline or diesel engine.

[0022] Fig. 3A illustrates a top view of an exemplary electrode 30 suitable for use in the anode 11 and / or the cathode 14. The electrode 30 is characterized by a width W and a length L, the latter defining a first end 31 and a second end 32. The length L and the width W define, for example, a top side and a bottom side. To the extent that the length L and the width W dimensions of the electrode 30 are described, they are applicable to either a current collector or a current collector in conjunction with a corresponding coating (for example, a lithium intercalation host material or a lithium-based active material), since when the latter is applied to the former, it is processed to have substantially the same length and width dimensions.The electrode 30, as defined by the length L and the width, is illustrated as a rectangle, but other shapes, such as oval shapes, are practical, where the length L comprises, for example, an average length and the width W an average width.

[0023] The electrode 30 further includes a first tab 33 extending from the first end 31 and a second tab 34 extending from the second end 32. In particular, the first tab 33 and second tab 34 extend from the current collector electrode 30 and are electrically connected thereto. A tab can be defined as a portion of an electrode that does not include, for example, an active material or a host material. The first tab 33 and the second tab 34 can comprise the same or a similar material of construction as the current collector electrode 30 or any other suitable electrically conductive material. A width of the first tab 33 and the second tab 34 can be smaller than the width W of the electrode 30, as will be described below. The electrode 30 (including the first tab 33 in the second tab 34) can, for example, be of a one-piece construction.The first tab 33 and the second tab 34 may generally be opposite each other and may, as shown in . Fig. 3A, be arranged symmetrically at the first end 31 and the second end 32. Alternatively, as shown in Fig. 3B, the first tab 33 and the second tab 34 may be arranged asymmetrically at the first end 31 and the second end 32, for example, to enable packaging of the electrode 30 enclosing the plurality of battery cells and / or to improve the electrical properties.

[0024] As in Fig. 3A and Fig. 3B, the electrode 30 further includes a first electron resistor 35 and a second electron resistor 36. Electron resistors advantageously distribute the current density in an electrode by interrupting the shortest flow path of electrons moving through the electrode. Accordingly, electron resistors improve current distribution through an electrode. An electron resistor comprises a region where electron flow is restricted or minimally possible. In some embodiments, an electron resistor comprises a slot. In a particular embodiment, an electron resistor comprises a slot in the current collector of an electrode. In some embodiments, an electron resistor comprises a region of the current collector in which no or substantially no active material or host material is present.In such embodiments, the electronic resistance can be formed by the electrode via laser ablation or metal blade notches of the active or host material. According to the invention, the electrode can be thicker near the center of the electrode's length to accommodate the increased current density induced by one or more electronic resistances.

[0025] The first electronic resistor 35 may extend longitudinally inward from the first end 31 and the second electronic resistor 36 may extend longitudinally inward from the first end 32. As shown in Fig. 3B for electrodes with asymmetric tabs, the electron resistor of a corresponding electrode side may be located closer to the center of the width of the electrode than the respective tab. In some embodiments, an electron resistor may be located adjacent to the electron tab of the same electrode side. For example, the first electron resistor 35 may be located adjacent to the first electrode tab 33 and / or the second electron resistor 36 may be located adjacent to the second electrode tab 34. The position of an electron resistor at an electrode may be determined by the orientation of the anode / cathode pairs in a battery cell. In particular, the anode and cathode may be stacked such that their respective length-width planes are substantially planar and arranged with the first end of the anode proximate the first end of the cathode.In such embodiments, the electrode resistance of the anode and / or the cathode can be arranged such that it is located between the first tab of the anode and the first tab, respectively. Likewise, the second electrode resistance of the anode and / or the cathode can be arranged such that it is located between the second tab of the anode and the second tab, respectively.

[0026] The electronic resistors can have different shapes and lengths. As in Fig. 3A, the electron resistance can be rectangular or substantially rectangular. As shown in Fig. 3B, electron resistors may be triangular. Other shapes and configurations of electron resistors are similarly practical, as will be understood by anyone skilled in the art after examining this invention. In some embodiments, the length of the electron resistors is less than half the electrode length. In some embodiments, where two electron resistors of a common electrode are asymmetric, the lengths of the electron resistors may exceed half the electrode length.

[0027] Fig. 4A illustrates a schematic side view of a battery pack 20 including a plurality of anodes 11 and cathodes 14, each insulated by a separator 18. Anodes 11 and cathodes 14 are shown without electron resistors 35 and 36 for clarity. The battery pack 20 may include a plurality of battery cells 10, each battery cell 10 including an anode 11 and a cathode 14. Generally, this applies to each of the anodes 11 and cathode 14, or alternatively, to each battery cell 10, such that the length-width planes of each electrode are substantially parallel (i.e., within 10 degrees). Such a stacked orientation provides strength and thermal advantages, unlike other electrode configurations, such as wound or coiled "jelly-roll" type electrodes.In some embodiments, a battery cell 10 or a plurality of anodes 11 and cathodes 14 may include a Z-type separator 18' as shown in FIG. Fig. 4B. The single Z-type separator 18' may be folded once or a plurality of times to accept one or a plurality of anodes 11 and cathodes 14. In particular, the one or a plurality of folds form a plurality of subsections of the separator 18', where each subsection may be positioned between two electrodes (e.g., between an anode 11 and a cathode 14). For each number of folds n, the separator 18' comprises n+1 subsections. Separators such as separator 18' may, for example, improve manufacturing efficiency.

[0028] A plurality of cathodes 14 can be electrically connected to the battery at the first end 31 via a first cathode bus bar 33' and to the battery second end 32 via a second cathode bus bar 34'. A plurality of anodes 11 can be electrically connected to the battery first end 31 via a first anode bus bar 33'' and to the battery second end 32 via a second anode bus bar 34''. Each bus bar can be electrically connected to different electrodes via the respective electrode tab. In particular, a first cathode bus bar 33' can be connected to a cathode tab or a plurality of first cathode tabs 33C at the battery first end 31, and the cathode second bus bar 34' can be connected to a cathode tab or a plurality of second cathode tabs 34C at the battery second end 32.Similarly, a first anode bus bar 33" may be connected to one or more of the first anode tabs 33A at the first end 31 of the battery, and the second anode bus bar 34" may be connected to one or more of the second anode tabs 34A at the second end of the battery 32. As shown, each bus bar is connected to a plurality of electrodes located within the box 19 and extends outwardly from the box 19 to electrically connect to various other circuits (not shown). In other embodiments, one or more cell tabs of one or more electrodes may extend outside the box 19 and connect to a respective bus bar.Bus bars 33' and 34' each connect to a corresponding positive battery terminal 37, and bus bars 33" and 34" each connect to a corresponding negative battery terminal 38. In some embodiments, bus bars 33' and 34' are each connected to a common positive battery terminal (as shown) and / or bus bars 33" and 34" are each connected to a common negative battery terminal (as shown).

[0029] In some embodiments, a battery pack 20 includes a plurality of anodes and a plurality of cathodes and may be configured such that one or more of the first tab of each anode overlaps and connects to the first tab of at least one other anode, the second tab of each anode overlaps and connects to the second tab of at least one other anode, the first tab of each cathode overlaps and connects to the first tab of at least one other cathode, and the second tab of each cathode overlaps and connects to the second tab of at least one other cathode. Fig. 4C illustrates a top view of such a battery pack 20, including a plurality of anodes 11 and a plurality of cathodes 14. Fig.4C illustrates a battery pack 20 including three anodes 11 and three cathodes 14 for illustrative purposes only and is not intended to limit the battery pack to fewer than three anodes 11 and cathodes 14 or more than three anodes 11 and cathodes 14. As illustrated, each of the three anodes includes a first tab (31A*, 31A**, and 31A***) of the anode, and each of the three cathodes includes a first tab (31C*, 31C**, and 31C***) of the cathode. As shown, consecutive first tabs of the anode overlap and consecutive first tabs of the cathode overlap. A similar configuration is practical at the second end 32 (not shown) of the battery pack 20.In some embodiments, one or more first tabs of the anode may overlap with a plurality of other first tabs of the anode, and / or one or more first tabs of the cathode may overlap with a plurality of first tabs of the cathode. A similar configuration is practical at the second end 32 (not shown) of the battery pack 20. Such a configuration allows for simple and effective electrical connection of the battery cells 10 and allows the tabs to be designed to maximize electrical and thermal performance. Furthermore, the overlapping tabs may simplify the manufacturing of a battery pack 20. For example, the tabs may be laser- or ultrasonically welded.Once a plurality of tabs are brought together, a bus bar can be electrically connected to a single point or a reduced number of points to establish an electrical connection to the battery pack 20.

[0030] The two-tab design of electrode 30 in combination with one or more electron resistors can be used by lithium metal batteries (e.g., Li-S batteries) and lithium-ion batteries and can provide them with numerous advantages, including, among others, improved (i.e., more uniform) current distribution, increased heat dissipation, reduced resistance, and a reduced or limited risk of lithium plating. At high charge currents, for example, the Li+ ion transport rate to an anode may exceed the rate at which Li+ ions are able to intercalate into the anode host material. At high charge currents, the Li+ ion transport rate to an anode may, for example, exceed the rate at which Li+ ions are able to intercalate into the anode host material. Accordingly, Li+ can be deposited as metallic Li because the conditions for lithium ion reduction are favored over those for intercalation.This problem can be particularly pronounced during rapid charging at high currents, charging at low ambient temperatures, and delayed lithium-ion movement and regenerative braking in vehicles (i.e., energy is captured from vehicle braking and used to charge an associated battery, such as battery 20). The lithium coating can impair battery performance and degrade battery life and durability in a variety of ways. In particular, the reduction of free lithium ions causes irreversible capacity loss within a battery cell, and non-homogeneous dendritic coating can cause a short circuit between two paired electrons. In particular, lithium coating can be caused and exacerbated by uneven current distribution.The advantages of the two-layer electrodes with specific aspect ratios as described herein enable higher charge / discharge voltages (higher discharge current) with minimal or reduced risk of lithium plating.

[0031] The two-tab electrodes (e.g., 30) and batteries (e.g., battery cell 10, battery pack 20) ​​including one or more electron resistors (e.g., 35, 36) are particularly advantageous when the electrode is characterized by a high aspect ratio. In particular, the electrodes 30 may comprise efficiencies greater than 1. In some embodiments, the electrodes 30 comprise efficiencies greater than about 2. In some embodiments, the electrodes 30 comprise efficiencies greater than about 2.5. In some embodiments, the electrodes 30 comprise efficiencies greater than or equal to about 3. In one example, an electrode 30 may comprise an aspect ratio of about 2.5 to about 10, or about 3 to about 8. In one example, an electrode 30 of the current collector may comprise a length of about 300 mm to about 600 mm and a width of about 50 mm to about 100 mm.In such an embodiment, the current collector may comprise a thickness of about 0.03 mm to about 0.03 mm or about 0.005 mm to about 0.025 mm. When an electrode composition (e.g., anode host material or cathode active material) is applied to the top side of the electrode and / or the bottom side of the electrode, the electrode may comprise a total thickness of up to about 0.5 mm or about 0.05 mm to about 0.5 mm.

[0032] Although the two-tab design slightly reduces the potential energy density of a battery enclosing electrode 30, the dimensions (i.e., efficiency) of electrode 30 provide high strength and effective heat dissipation, while the two tabs provide improved electrical properties, such as uniform current density. Electron resistances improve current distribution in electrodes and current, delivering increased power and longer electron lifetime. Furthermore, the elongated battery shape (i.e., optional high-efficiency electrodes) offers improved packaging aspects in various applications, as a single electrode 30 can replace two smaller electrodes aligned end-to-end, reducing the wasted space caused by the inner tabs.

Claims

[1] Lithium battery cell (10) comprising: an electrolyte (17); an anode (11) disposed within the electrolyte (17) and including a current collector (12) having the following: a length (L), the length (L) defining a first end (31) and a second end (32), a width (W), a host material of the anodes (11) disposed on the current collector (12) of the anode (11) between the first end (31) and the second end (32), a first tab (33) extending from the first end (31), and a second tab (34) extending from the second end (32); and a cathode (14) disposed within the electrolyte (17) and including a current collector (15) having: a length (L), the length (L) defining a first end (31) and a second end (32), a width (W), an active material of the cathode (14) disposed on the current collector (15) of the cathode (14) between the first end (31) and the second end (32), a first tab (33) extending from the first end (31), and a second tab (34) extending from the second end (32); characterized by , that the current collector (12) of the anode (11) has a first anode electronic resistor (35) extending longitudinally inward from the first end (31), and the current collector (15) of the cathode (14) has a first cathode electronic resistor (35) extending longitudinally inward from the first end (31); wherein one or more of the anodes (11) and cathodes (14) are thicker near the middle of the length. [2] Battery pack comprising: a plurality of anodes (11), each anode (11) including the following: an anode length (L), the anode length (L) defining a first end (31) of the anode (11) and a second end (32) of the anode (11), an anode width (W), a first anode tab (33) extending from the first end (31) of the anode, and a second anode tab (34) extending from the second end (32) of the anode, a first anode electronic resistor (35) extending longitudinally inward from the first end (31), and a second anode electronic resistor (36) extending longitudinally inward from the second end (32); a plurality of cathodes (14), each cathode (14) including: a cathode length (L), the cathode length (L) defining a first end (31) of the cathode (14) and a second end (32) of the cathode (14), a cathode width (W), a first cathode tab (33) extending from the first end (31) of the cathode (14) and a second cathode tab (34) extending from the second end (32) of the cathode (14), a first cathode electronic resistor (35) extending longitudinally inward from the first end (31), and a second cathode electronic resistor (36) extending longitudinally inward from the second end (32); a bus bar of the anode (11) connecting the plurality of first anode tabs (33) and the plurality of second anode tabs (34) to a negative pole; and a cathode busbar (14) connecting the plurality of first cathode tabs (33) and the plurality of second cathode tabs (34) to a positive terminal; wherein the anodes (11) and cathodes (14) can be stacked such that their respective length-width planes are substantially flat; where: (i) the first tab (33) and the second tab (34) of each anode (11) are opposite one another and are arranged centrally at the first end (31) and the second end (32) of the anode (11), the two anode electron resistors extending inwards from diagonally opposite end portions of the respective anode (11); or (ii) the first tab (33) of each cathode (14) is asymmetrical to the second tab (34) of each cathode (14) and the first tab (33) of each anode (11) is asymmetrical to the second tab (34) of each anode (11), wherein the two anode electronic resistors are located in the middle of the width (W) of each anode (11) and wherein the two cathode electronic resistors are also located in the middle of the width (W) of each cathode (14). [3] Battery pack for an electric or hybrid vehicle, comprising: a plurality of stacked battery cells, each cell comprising: an anode (11) having a length (L), the length (L) defining a first end (31) and a second end (32), a width (W), a first tab (33) extending from the first end (31) of the anode (11), and a second tab (34) extending from the second end (32) of the anode (11), a first anode electronic resistor (35) extending longitudinally inward from the first end (31), and a second anode electronic resistor (36) extending longitudinally inward from the second end (32); and a cathode (14) having a length (L), the length (L) defining a first end (31) and a second end (32), a width (W), a first tab (33) extending from the first end (31) of the cathode (14) and a second tab (34) extending from the second end (32) of the cathode (14), a first cathode electronic resistor (35) extending longitudinally inward from the first end (31), and a second cathode electronic resistor (36) extending longitudinally inward from the second end (32); wherein the first tab (33) of each anode (11) overlaps and connects to the first tab (33) of at least one other anode (11), the second tab (34) of each anode (11) overlaps and connects to the second tab (34) of at least one other anode (11), the first tab (33) of each cathode (14) overlaps and connects to the first tab (34) of at least one other cathode (14), and the second tab (34) of each cathode (14) overlaps and connects to the second tab (34) of at least one other cathode, and wherein each anode (11) has a length-to-width ratio of at least 1 and each cathode (14) has a length-to-width ratio of at least 1; and wherein: (i) the first tab (33) and the second tab (34) of each anode (11) are opposite one another and are arranged centrally at the first end (31) and the second end (32) of the anode (11), the two anode electron resistors extending inwards from diagonally opposite end portions of the respective anode (11); or (ii) the first tab (33) of each cathode (14) is asymmetrical to the second tab (34) of each cathode (14) and the first tab (33) of each anode (11) is asymmetrical to the second tab (34) of each anode (11), wherein the two anode electronic resistors are located in the middle of the width (W) of each anode (11) and wherein the two cathode electronic resistors are also located in the middle of the width (W) of each cathode (14). [4] Battery pack according to claim 2 or 3, wherein the first anode electronic resistor (35) and / or the first cathode electronic resistor (35) each comprise a slot in the anode current collector or in the cathode current collector. [5] Battery pack according to one of claims 2 to 4, wherein the first anode electronic resistor (35) and / or the first cathode electronic resistor (35) comprises a region with substantially no anode or cathode host material. [6] Battery pack according to one of claims 2 to 5, wherein the anode (11) and cathode (14) can be stacked such that their respective length-width planes are substantially flat with the first end (31) of the anode (11) near the first end (31) of the cathode (14), wherein the first anode electronic resistor (35) is located between the first tab (33) of the anode (11) and the first tab (33) of the cathode (14) and / or the first cathode electronic resistor (35) is located between the first tab (33) of the anode (11) and the first tab (33) of the cathode (14). [7] A battery pack according to any one of claims 2 to 6, wherein each of the first anode electronic resistors and the second anode electronic resistor (36) has a length that is less than half the anode length and each of the first cathode electronic resistors and the second cathode electronic resistor (36) has a length that is less than half the length (L) of the cathode (14). [8] A battery pack according to any one of claims 2 to 7, wherein one or more of the anodes (11) and cathodes (14) are thicker near the center of their length.

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