EP4732348A1

EP4732348A1 - Rechargeable battery with multilayer monolithic electrode

Info

Publication number: EP4732348A1
Application number: EP24734127.4A
Authority: EP
Inventors: Lu Yu; Parthasarathy M. Gomadam; Prabhakar A. Tamirisa
Original assignee: Medtronic Inc
Current assignee: Medtronic Inc
Priority date: 2023-06-26
Filing date: 2024-06-03
Publication date: 2026-04-29
Also published as: WO2025003797A1; CN121444209A

Abstract

Electrochemical cells with improved power density and energy density capabilities are provided herein including an electrode an electrode with a dense layer and a porous layer adjacent and electrically coupled to the dense layer. The dense layer has a low porosity relative to the porous layer in order to increase the energy density of the cell. The porous layer has a porosity greater than the porosity of the dense layer in order to provide improved power density.

Description

RECHARGEABLE BATTERY WITH MULTILAYER MONOLITHIC ELECTRODE

[0001] This application claims the benefit of U.S. Provisional Patent Application, Serial No. 63/523,298, filed June 26, 2023, the entire content in which is incorporated herein by reference.

TECHNICAL FIELD

[0002] The present disclosure generally relates to the field of lithium-ion batteries or cells.

BACKGROUND

[0003] Lithium-ion batteries or cells include one or more positive electrodes, one or more negative electrodes, and, often, a liquid electrolyte provided within a case or housing. Separators made from a porous polymer or other suitable material may also be provided between the positive and negative electrodes to prevent direct contact between adjacent electrodes, and electrolytes penetrate through pores in this porous polymer.

[0004] Energy density and power density are two key attributes of batteries. Energy density is the amount of energy in the battery compared to the volume of the battery and may be expressed, for example, as watt-hours per liter (Wh/L) or as Joules per liter (J/L). Power density is the time rate of energy transfer of which a battery is capable compared to the volume of the battery and may be expressed, for example, in watts per liter (W/L). Both higher energy density and higher power density are generally desirable. However, battery design characteristics promoting higher energy density may commonly afford lower power density. Likewise, battery design characteristics promoting higher power density may commonly afford lower energy density. There is a general interest in improving energy density of batteries without sacrificing power density and vice-versa.

[0005] In general, batteries with greater energy density tend to last longer in discharge and may allow for miniaturization, such as for use small formfactor devices. In general, the energy density of a primary cell (that is, a cell configured to be discharged once and then discarded or recycled) is greater than the energy density of a secondary cell (that is, a rechargeable cell configured to be cycled through charge and discharge cycles for repeated use). In many applications, rechargeable batteries are preferred over primary batteries for benefits such as improving the lifespan of a device and reducing waste. Rechargeable batteries are especially desirable where replacing a primary battery would be difficult or impossible, such as in implantable medical devices, where accessing the device to replace its battery (or the device itself) could require an inpatient procedure. However, rechargeable batteries in implantable medical devices generally must be recharged frequently because of lower energy density and small form factor.

[0006] High power density is generally desirable for use in high-current applications, such as Bluetooth Low-Energy (BTLE) applications. BTLE may be used, for example, to transmit data from a battery-powered device to another device, such as from an implantable medical device to an external device for analyzing or displaying the transmitted data.

[0007] In general, there is a need for an electrochemical cell with increased energy density that is also capable of high-current applications, which could improve the lives, comfort, and quality of care for patients living with or receiving implantable medical devices such as pacemakers, insulin pumps, cardioverter-defibrillators, drug delivery pumps, and neuro stimulator s .

SUMMARY

[0008] For higher power density, batteries may generally be designed with relatively thin, porous, high surface area electrodes. Batteries designed with relatively thin, porous, high surface area electrodes tend to have lower energy density, for example, due to a relative greater amount of inactive material, such as current collectors and separators (compared to batteries having thicker electrodes). Conversely, for higher energy density, batteries may generally be designed with relatively thick, dense, low surface area electrodes. Batteries designed with relatively thick, dense, low surface area electrodes tend to afford lower power density, for example, due to ion transport limitations.

[0009] As described herein, electrochemical cells may be provided with multilayer monolithic electrodes having both a relatively thick, dense, low surface area layer and a relatively thin, porous, high surface area layer, together providing relatively high energy density with power density to support high-current applications, such as BTLE.

[0010] Embodiments disclosed herein may include an electrochemical cell with an electrode having a dense layer, a porous layer adjacent and electrically coupled to the dense layer, a current collector electrically coupled to the dense layer, a second electrode, and a separator between the second electrode and the porous layer of the electrode. The dense layer may have a porosity of less than 20 % and the porous layer may have a porosity greater than the porosity of the dense layer.

[0011] The porosity of the dense layer may be less than 10 % less or than 5 %. The dense layer may have a thickness of 0.3 millimeters (mm) or greater or 0.4 mm or greater. The dense layer may have a thickness at least 50 % greater than a thickness of the porous layer, at least two times a thickness of the porous layer, or at least three times a thickness of the porous layer. The dense layer may include a dry-formation electrode material. The dense layer of the electrode may be discharged at a discharge rate of C/24 or less, C/4, 383 or less, C/8, 766 or less, or C/87, 660 or less.

[0012] The porosity of the porous layer may be at least 20 % or at least 50 %. The porosity of the porous layer may be at least 50 % greater than the porosity of the dense layer, at least two times the porosity of the dense layer, or at least three times the porosity of the dense layer. The porous layer of the electrode may be discharged at a discharge rate of 1C rate or greater, 2C or greater, or 5C or greater.

[0013] A cross-sectional area of the electrode may be less than 500 times a thickness of the electrode or less than 50 times a thickness of the electrode.

[0014] The current collector may include one or both of a mesh and a grid.

[0015] The cell may have an energy density of 100 Wh/L or greater, 300 Wh/L or greater, or 500 Wh/L or greater. The cell may be pulse-discharged at a discharge rate C/50 or greater, C/20 or greater, or C/5 or greater.

[0016] Embodiments described herein may further include an electrochemical cell with a cathode and an anode. The cathode may include a cathode dense layer with a porosity of less than 20 % and a cathode porous layer with a porosity greater than the porosity of the cathode dense layer. The cathode porous layer may be adjacent and electrically coupled to the cathode dense layer. The anode may include an anode dense layer with a porosity of less than 20 % and an anode porous layer with a porosity greater than the porosity of the anode dense layer. The anode porous layer may be adjacent and electrically coupled to the anode dense layer. The electrochemical cell may further include a cathode current collector electrically coupled to the cathode dense layer, an anode current collector electrically coupled to the anode dense layer, and a separator between the anode porous layer and the cathode porous layer. [0017] The porosity of one or both of the cathode dense layer or the anode dense layer may be less than 10 % or less than 5 %. One or both of the cathode dense layer and the anode dense layer may have a thickness of at least 0.3 mm or at least 0.4 mm. The cathode dense layer may have a thickness at least 50 % greater than a thickness of the cathode porous layer, or the anode dense layer may have a thickness at least 50 % greater than a thickness of the anode porous layer, or both. The cathode dense layer may have a thickness of at least two times a thickness of the cathode porous layer, or the anode dense layer may have a thickness of at least two times a thickness of the anode porous layer, or both. The cathode dense layer may have a thickness of at least three times a thickness of the cathode porous layer, or the anode dense layer may have a thickness of at least three times a thickness of the anode porous layer, or both. One or both of the cathode dense layer and the anode dense layer may include a dry-formation electrode material. The cathode dense layer of the electrode may be discharged at a discharge rate of C/24 or less, C/4, 383 or less, C/8, 766 or less, or C/87, 660 or less; or the anode dense layer of the electrode may be discharged at a discharge rate of C/24 or less, C/4, 383 or less, C/8, 766 or less, or C/87, 660 or less; or both.

[0018] The porosity of one or both of the cathode porous layer or the anode porous layer may be 20 % or greater or 50 % or greater. The porosity of the cathode porous layer may be at least 50 % greater than the porosity of the cathode dense layer, or the porosity of the anode porous layer may be at least 50 % greater than the porosity of the anode dense layer, or both. The porosity of the cathode porous layer may be at least two times the porosity of the cathode dense layer, or the porosity of the anode porous layer may be at least two times the porosity of the anode dense layer, or both. The porosity of the cathode porous layer may be at least three times the porosity of the cathode dense layer, or the porosity of the anode porous layer may be at least three times the porosity of the anode dense layer, or both. One or both of the cathode porous layer and the anode porous layer may have a thickness of 0.2 mm or less or 0.1 mm or less. The cathode porous layer of the electrode may be discharged at a discharge rate of 1C rate or greater, 2C or greater, or 5C or greater; or the anode porous layer of the electrode may be discharged at a discharge rate of 1C rate or greater, 2C or greater, or 5C or greater; or both.

[0019] A cross-sectional area of the cathode may be less than 500 times a thickness of the cathode, or a cross-sectional area of the anode may be less than 500 times a thickness of the anode, or both. A cross-sectional area of the cathode may be less than 100 times a thickness of the cathode, or a cross-sectional area of the anode may be less than 100 times a thickness of the anode, or both. A cross-sectional area of the cathode may be less than 50 times a thickness of the cathode, or a cross-sectional area of the anode may be less than 50 times a thickness of the anode, or both.

[0020] One or both of the cathode current collector and the anode current collector may include one or both of a mesh and a grid.

[0021] The cell may have an energy density of 100 Wh/L or greater, 300 Wh/L or greater, or 500 Wh/L or greater. The cell may be pulse-discharged at a discharge rate C/50 or greater, C/20 or greater, or C/5 or greater.

[0022] Embodiments described herein may further include an electrochemical cell with a plurality of unit cells, each unit cell having a cathode and an anode. The cathode may include a cathode dense layer with a porosity of less than 20 % and a cathode porous layer with a porosity greater than the porosity of the cathode dense layer. The cathode porous layer may be adjacent and electrically coupled to the cathode dense layer. The anode may include an anode dense layer with a porosity of less than 20 % and an anode porous layer with a porosity greater than the porosity of the anode dense layer. The anode porous layer may be adjacent and electrically coupled to the anode dense layer. The electrochemical cell may further include a cathode current collector electrically coupled to the cathode dense layer, an anode current collector electrically coupled to the anode dense layer, and a separator between the anode porous layer and the cathode porous layer.

[0023] The cathode current collector of one of the plurality of unit cells may be the cathode current collector of another of the plurality of unit cells, or the anode current collector of one of the plurality of unit cells may be the anode current collector of another of the plurality of unit cells, or both. The cathode of one of the plurality of unit cells may be the cathode of another of the plurality of unit cells, or the anode of one of the plurality of unit cells may be the anode of another of the plurality of unit cells, or both.

[0024] The details of one or more aspects of the disclosure are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the techniques described in this disclosure will be apparent from the description and drawings, and from the claims. BRIEF DESCRIPTION OF DRAWINGS

[0025] FIGS. 1A-C are cross section side views of illustrative electrochemical cells with a multilayer monolithic electrode.

[0026] FIG. 2 is a cross section side view of an illustrative electrochemical cell including a second multilayer monolithic electrode.

[0027] FIG. 3 is a cross section side view of an illustrative electrochemical cell including additional multilayer monolithic electrodes.

[0028] FIG. 4 is a cross section side view of a portion of an illustrative electrochemical cell with a plurality of unit cells.

[0029] FIG. 5 is a cross section side view of a portion of an illustrative electrochemical cell including a plurality of overlapping unit cells.

[0030] The figures are rendered primarily for clarity and, as a result, are not necessarily drawn to scale. Moreover, various structure/components may be shown diagrammatically or removed from some of or all the views to better illustrate aspects of the depicted embodiments, or where inclusion of such structure/components is not necessary to an understanding of the various illustrative embodiments described herein. The lack of illustration/description of such structures/components in a particular figure is, however, not to be interpreted as limiting the scope of the various embodiments in any way.

DETAILED DESCRIPTION

[0031] All scientific and technical terms used herein have meanings commonly used in the art, unless otherwise specified. The definitions provided herein are to facilitate understanding of certain terms used frequently herein and are not meant to limit the scope of the present disclosure.

[0032] Unless otherwise indicated, the terms “polymer,” “polymerized monomers,” and “polymeric material” include, but are not limited to, organic homopolymers, copolymers, such as, for example, block, graft, random and alternating copolymers, terpolymers, etc., and blends and modifications thereof. Furthermore, unless otherwise specifically limited, the term “polymer” shall include all possible geometrical configurations of the material. These configurations include, but are not limited to, isotactic, syndiotactic, and atactic symmetries. [0033] The term “substantially” modifies the term that follows by at least about 90 %, at least about 95 %, or at least about 98 %. “Substantially” includes “significantly,” which refers to statistical significance.

[0034] The term “not substantially” modifies the term that follows by not more than 25 %, not more than 10 %, not more than 5 %, or not more than 2 %.

[0035] In this disclosure, all numbers are assumed to be modified by the term “about,” which encompasses the term “exactly.” As used herein in connection with a measured quantity, the term “about” refers to that variation in the measured quantity as would be expected by the skilled artisan making the measurement and exercising a level of care commensurate with the objective of the measurement and the precision of the measuring equipment used.

[0036] As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” include plural referents unless the content clearly dictates otherwise. It should also be noted that the term “or” is generally employed in its sense including “and/or” unless the content clearly dictates otherwise. The terms “and/or” and “any combination thereof’ and their grammatical equivalents as used herein, can be used interchangeably. These terms can convey that any combination is specifically contemplated. Solely for illustrative purposes, the following phrases “A, B, and/or C” or “A, B, C, or any combination thereof’ can mean “A individually; B individually; C individually; A and B; B and C; A and C; and A, B, and C.” The term “or” can be used conjunctively or disjunctively unless the context specifically refers to a disjunctive use.

[0037] The recitations of numerical ranges by endpoints include all numbers subsumed within that range (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, 5, etc. and 10 or less includes 10, 9.4, 7.6, 5, 4.3, 2.9, 1.62, 0.3, etc.). Where a range of values is “up to,” “at most,” or “at least” a particular value, that value is included within the range.

[0038] As used herein, “have,” “having,” “include,” “including,” “comprise,” “comprising,” or the like are used in their open-ended sense, and generally mean “including, but not limited to.” It will be understood that “consisting essentially of,” “consisting of,” and the like are subsumed in “comprising” and the like. As used herein, “consisting essentially of,” as it relates to a composition, product, method, or the like, means that the components of the composition, product, method, or the like are limited to the enumerated components and any other components that do not materially affect the basic and novel characteristic(s) of the composition, product, method, or the like.

[0039] As used in this specification and claim(s), the words “comprising” (and any form of comprising, such as “comprise” and “comprises”), “having” (and any form of having, such as “have” and “has”), “including” (and any form of including, such as “includes” and “include”) or “containing” (and any form of containing, such as “contains” and “contain”) are inclusive or open-ended and do not exclude additional, unrecited elements or method steps. It is contemplated that any embodiment discussed in this specification can be implemented with respect to any method or composition of the present disclosure, and vice versa. Furthermore, compositions of the present disclosure can be used to achieve methods of the present disclosure. Such inclusive or open-ended words encompass more restrictive or closed terms or phrases, such as “consisting” or “consisting essentially.” [0040] The words “preferred” and “preferably” refer to embodiments that may afford certain benefits, under certain circumstances. However, other embodiments may also be preferred, under the same or other circumstances. Furthermore, the recitation of one or more preferred embodiments does not imply that other embodiments are not useful and is not intended to exclude other embodiments from the scope of the disclosure, including the claims.

[0041] Reference in the specification to “some embodiments,” “an embodiment,” “one embodiment,” “embodiments,” “one or more embodiments,” or “other embodiments” means that a particular feature, structure, aspect, or characteristic described in connection with the embodiments is included in at least some embodiments, but not necessarily all embodiments, of the present disclosures.

[0042] Any direction referred to herein, such as “top,” “bottom,” “left,” “right,” “upper,” “lower,” and other directions and orientations are described herein for clarity in reference to the figures and are not to be limiting of an actual device or system or use of the device or system. Devices or systems as described herein may be used in a number of directions and orientations.

[0043] In several places throughout the application, guidance is provided through examples, which examples, including the particular aspects thereof, can be used in various combinations and be the subject of claims. In each instance, the recited list serves only as a representative group and should not be interpreted as an exclusive list. It is to be understood that the particular examples, materials, amounts, and procedures are to be interpreted broadly in accordance with the scope and spirit of the present disclosure. [0044] Reference will now be made in greater detail to various embodiments of the subject matter of the present disclosure, one or more embodiments of which are illustrated in the accompanying drawings. Like numbers used in the figures refer to like components and steps. However, it will be understood that the use of a number to refer to a component in a given figure is not intended to limit the component in another figure labeled with the same number. In addition, the use of different numbers to refer to components in different figures is not intended to indicate that the different numbered components cannot be the same as or similar to other numbered components.

[0045] A cross section side view of an illustrative electrochemical cell 100 with a multilayer monolithic electrode is shown in FIG. 1A. The electrochemical cell 100 includes a first multilayer monolithic electrode 110 and a second electrode 120. The first electrode 110 includes a dense layer 112 and a porous layer 114. The first electrode 110 and the second electrode 120 may have opposite polarities. The electrochemical cell 100 may include a separator 130 between the second electrode 120 and the porous layer 114 of the first electrode 110.

[0046] A current collector 140 may be electrically coupled to the first electrode 110. The current collector 140 may be electrically coupled to the dense layer 112 of the first electrode 110. As shown in FIG. 1A, the dense layer 112 of the first electrode 110 may be between the current collector 140 and the porous layer 114 of the first electrode 110.

[0047] Cross section side views of illustrative electrochemical cells 100 similar to the cell of FIG. 1A are shown in FIGS. IB and 1C, which illustrate alternative or additional positions of the current collector 140. As shown in FIG. IB, the current collector 140 may be adjacent, in contact with, or at least partially in contact with an interface region 113 (or interface, or boundary) between the dense layer 112 and the porous layer 114 of the first electrode 110. In such embodiments, the current collector 140 may be between at least a portion of the dense layer 112 of the first electrode 110 and at least a portion of the porous layer 114 of the first electrode 110.

[0048] As shown in FIG. 1C, the current collector 140 may be between a back surface 116 (or a back surface region) of the dense layer 112 and the interface region 113 between the dense layer 112 and the porous layer 114 of the first electrode 110. In such embodiments, the current collector 140 may extend from within the first electrode 110 to or beyond a surface of the first electrode 110. The current collector 140 may extend to or beyond a top surface 118 (or top surface region) of the first electrode 110, as an example. [0049] In one or more embodiments, the electrochemical cell 100 may include two or more current collectors 140 (not shown in FIGS. 1A-C). Each current collector 140 may be adjacent or in contact with the interface region 113 between the dense layer 112 and the porous layer 114 (for example, as shown in FIG. IB), may be adjacent or in contact with the back surface 116 (or back surface region) of the dense layer 112 (for example, as shown in FIG. 1A), may be between the back surface 116 of the dense layer 112 and the interface region 113 (for example, as shown in FIG. 1C), or may extend from within the first electrode 110 to or beyond a surface of the first electrode 110 (for example, as shown in FIG. 1C).

[0050] In some embodiments, the electrochemical cell 100 may include one or more second electrode current collectors electrically connected to the second electrode 120. Each second electrode current collector may be adjacent to a front surface (not explicitly labeled in the figures) of the second electrode 120, may be between the front surface and a back surface (not explicitly labeled in the figures) of the second electrode 120, or may extend from within the second electrode 120 to or beyond a surface of the second electrode 120.

[0051] The electrochemical cell 100 may include an electrolyte (not shown). The electrochemical cell 100 may be at least partially disposed within a housing (not shown). [0052] A cross section side view of an illustrative electrochemical cell 200 including a second multilayer monolithic electrode is shown in FIG. 2. The electrochemical cell 200 includes a first multilayer monolithic electrode 210 and a second multilayer monolithic electrode 220. The first electrode 210 may include a first electrode dense layer 212 and a first electrode porous layer 214. The second multilayer monolithic electrode 220 may include a second electrode dense layer 222 and a second electrode porous layer 224. The electrochemical cell 200 includes a separator 230 between the first electrode 210 and the second electrode 220. The separator 230 may be between the first electrode porous layer 214 and the second electrode porous layer 224.

[0053] In one or more embodiments according to aspects of FIG. 2, a first electrode current collector 240 is electrically coupled to the first electrode dense layer 212. As shown in FIG. 2, the first electrode current collector 240 may be adjacent, in contact with, or at least partially in contact with a back surface (not labeled) of the first electrode dense layer 212. The electrochemical cell 200 may include one or more additional first electrode current collectors (not shown in FIG. 2) electrically coupled to the first electrode dense layer 212. Each first electrode current collector (for example, the first electrode current collector 240) may be adjacent or in contact with a first electrode interface region 213 between the first electrode dense layer 212 and the first electrode porous layer 214, may be adjacent or in contact with a back surface (or back surface region, not labeled)) of the first electrode dense layer 212 (for example, as shown in FIG. 2), may be between the back surface of the first electrode dense layer 212 and the first electrode interface region 213, or may extend from within the first electrode 210 to or beyond a surface of the first electrode 210.

[0054] In some embodiments, a second electrode current collector 250 is electrically coupled to the second electrode dense layer 222. The second electrode current collector 250 may be adjacent, in contact with, or at least partially in contact with a back surface (not labeled) of the second electrode dense layer 222. The electrochemical cell 200 may include one or more additional second electrode current collectors (not shown in FIG. 2) electrically coupled to the second electrode dense layer 222. Each second electrode current collector (for example, the second electrode current collector 250) may be adjacent or in contact with a second electrode interface region 223 between the second electrode dense layer 222 and the second electrode porous layer 224, may be adjacent or in contact with a back surface (or back surface region, not labeled) of the second electrode dense layer 222 (for example, as shown in FIG. 2), may be between the back surface of the second electrode dense layer 222 and the second electrode interface region 223, or may extend from within the second electrode 220 to or beyond a surface of the second electrode 220. [0055] A cross section side view of an illustrative electrochemical cell 300 including additional multilayer monolithic electrodes is shown in FIG. 3. The electrochemical cell 300 may include a first multilayer monolithic electrode 310a and a second multilayer monolithic electrode 320a. The first electrode 310a may include a first electrode dense layer 312a and a first electrode porous layer 314a. The second electrode 320a may include a second electrode dense layer 322a and a second electrode porous layer 324a. The electrochemical cell 300 may include a first separator 330a between the first electrode porous layer 314a and the second electrode porous layer 324a. The electrochemical cell 300 may include one or more current collectors, such as a first electrode current collector 340a electrically coupled to the first electrode dense layer 312a. For another example, a second electrode current collector 350a may be electrically coupled to the second electrode dense layer 322a.

[0056] In some embodiments and as shown in FIG. 3, the electrochemical cell 300 may further include a third multilayer monolithic electrode 310b with a third electrode dense layer 312b and a third electrode porous layer 314b. The third electrode 310b may have the same polarity as the first electrode 310a. The third electrode dense layer 312b may be adjacent (such as directly adjacent) the first electrode dense layer 312a or a back current collector 360 may be between (that is, separating or at least partially separating) the third electrode dense layer 312b and the first electrode dense layer 312a, as depicted in FIG. 3. A third electrode current collector 340b may be electrically coupled to the third electrode dense layer 312b.

[0057] A second separator 330b may be between the third electrode porous layer 314b and a porous layer 324b of a fourth multilayer monolithic electrode 320b. The fourth electrode 320b may include a fourth electrode dense layer 322b. The fourth electrode 320b may have the same polarity as the second electrode 320a, which may be opposite the polarity of the first electrode 310a and the third electrode 310b. A fourth electrode current collector 350b may be electrically coupled to the fourth electrode dense layer 322b.

[0058] In one or more embodiments, and as shown in FIG. 3, the electrochemical cell 300 may include the first electrode current collector 340a, the third electrode current collector 340b, and the back current collector 360 (that is, a current collector located between or shared by the first electrode 310a and the third electrode 310b). Additionally or alternatively, the electrochemical cell 300 may include more or fewer current collectors electrically connected to the first electrode 310a and the third electrode 310b.

[0059] In at least one embodiment, the back current collector 360 may be between the first electrode dense layer 312a and the third electrode dense layer 312b. That is, the first electrode dense layer 312a and the third electrode dense layer 312b may be separated or at least partially separated by the back current collector 360. Additionally or alternatively, the first and third electrodes 310a, 310b may be directly adjacent. In one or more embodiments, the first and third electrodes 310a, 310b may establish a single monolithic multilayer electrode, for example, including the first electrode dense layer 312a, the third electrode dense layer 312b, the first electrode porous layer 314a, and the third electrode porous layer 314b.

[0060] A cross section side view of a portion of an illustrative electrochemical cell 400 including a plurality of unit cells is shown in FIG. 4. The electrochemical cell 400 may include a plurality of unit cells (that is, a plurality of opposite-polarity pairs of multilayer monolithic electrodes), including a unit cell 402. Each of the plurality of unit cells, as illustrated by the unit cell 402, may include a first multilayer monolithic electrode 410 and a second multilayer monolithic electrode 420. The first electrode 410 may include a first electrode dense layer 412, a first electrode porous layer 414, and one or more current collectors (for example, a first electrode current collector 440) electrically coupled to the first electrode dense layer 412. The second electrode 420 may include a second electrode dense layer 422, a second electrode porous layer 424, and one or more current collectors (for example, a second electrode current collector 450) electrically coupled to the second electrode dense layer 422. The unit cell 402 may include a separator 430 between the first electrode porous layer 414 and the second electrode porous layer 424.

[0061] A cross section side view of a portion of an illustrative electrochemical cell 500 including a plurality of overlapping unit cells is shown in FIG. 5. The electrochemical cell 500 may include a plurality of unit cells. In one or more embodiments, and as shown in FIG. 5, each unit cell of the plurality of unit cells may overlap with another unit cell of the plurality of unit cells. That is, each unit cell of the plurality of unit cells may share an electrode with another unit cell of the plurality of unit cells. For example, the electrochemical cell 500 may include a first unit cell 502 and a second unit cell 504.

[0062] In some embodiments, the electrochemical cell 500 may include a first multilayer monolithic electrode 510 with a dense layer 512 and a first porous layer 514. The first electrode 510 may further include a second porous layer 515 and may include one or more current collectors (not shown) electrically coupled to the dense layer 512 of the first electrode 510. A second multilayer monolithic electrode 520 may include a dense layer 522 and a first porous layer 524. The second electrode 520 may further include a second porous layer 525 and may include one or more current collectors (not shown) electrically coupled to the second electrode dense layer 522. A separator 540 may be between the first porous layer 514 of the first electrode 510 and the first porous layer 524 of the second electrode 520. The first electrode 510 and the second electrode 520 may have opposite polarities, which may be described as establishing the first unit cell 502, or a pair of opposite-polarity electrodes with a separator between the electrodes.

[0063] The electrochemical cell 500 may further include a third multilayer monolithic electrode 530 with a dense layer 532 and a first porous layer 534. The third electrode 530 may further include a second porous layer 535 and may include one or more current collectors (not shown) electrically coupled to the dense layer 532 of the third electrode 530. A separator 542 may be between the first porous layer 534 of the third electrode 530 and the second porous layer 525 of the second electrode 520. The third electrode 530 may have a polarity opposite the polarity of the second electrode 520, which may be described as establishing the second unit cell 504, or a pair of opposite-polarity electrodes with a separator between the electrodes.

[0064] It will be understood in light of the present disclosure that any suitable electrochemical cell geometry or construction (such as rectangular, prismatic, cylindrical, coiled, stacked, as examples) may be used and the disclosure is not limited in this regard. [0065] Illustrative electrochemical cells described herein may provide improved energy density. In one or more embodiments, for example, the electrochemical cell may have an energy density between 1 Wh/L and 1,000 Wh/L or between 100 Wh/L and 500 Wh/L. Cell energy densities may additionally or alternatively include 1 Wh/L or greater, 5 Wh/L or greater, 10 Wh/L or greater, 50 Wh/L or greater, 100 Wh/L or greater, 250 Wh/L or greater, 400 Wh/L or greater, 500 Wh/L or greater, 600 Wh/L or greater, or 800 Wh/L or greater.

[0066] As described herein, some embodiments may provide improved power density. In one or more embodiments, for example, the electrochemical cell may have a power density between 0.1 W/L and 100,000 W/L or between 10 W/L and 1,000 W/L. Cell power densities may additionally or alternatively include 0.1 W/L or greater, 1 W/L or greater, 10 W/L or greater, 50 W/L or greater, 100 W/L or greater, 500 W/L or greater, 750 W/L or greater, 1,000 W/L or greater, 10,000 W/L or greater, 50,000 W/L or greater, or 80,000 W/L or greater.

[0067] As described herein, illustrative electrochemical cells may be suitable for high- current applications. The electrochemical cell may be capable of producing BTLE pulses, for example. The electrochemical cell may be capable of producing such high-current pulses at improved load voltages. For example, the electrochemical cell may be capable of producing a high-current pulse of at least 7 milliamps (mA) with a minimum voltage of at least 2 V. For further examples, the electrochemical cell may be capable of producing a high-current pulse of at least 7 mA with a minimum voltage between 1.5 V and 5 V or between 2 V and 4 V. Cell minimum voltages for producing a high-current pulse of at least 7 mA may additionally or alternatively include at least 0 V, at least 0.5 V, at least 1 V, at least 1.5 V, at least 2 V, at least 2.5 V, or at least 4 V.

[0068] In some embodiments, as described herein, the electrochemical cell may include one or more cathodes, which may be the first multilayer monolithic electrode 110 or the second electrode 120 of FIGS. 1A-1C, as examples. For further examples, the one or more cathodes may be the first multilayer monolithic electrode 510 and the third multilayer monolithic electrode 530 of FIG. 5, or may be the second multilayer monolithic electrode 520. It will be understood in light of the present disclosure that any suitable cathode configuration may be used and the disclosure is not limited in this regard.

[0069] The one or more cathodes may each be made of any suitable material or combination of materials. Suitable cathode materials may be selected based on capacity, interfacial kinetics, electrical conductivity, lithium ion diffusivity particle size, particle surface area, density, porosity, or tortuosity, as examples. Suitable cathode materials may include lithium cobalt oxide, as an example. For further examples, suitable cathode materials may include lithium-metal oxides (such as LiM C , Li(Ni_xMn_yCo_z)O2), vanadium oxides, olivines (such as LiFePC ), rechargeable lithium oxides, silver vanadium oxide, carbon monofluoride, or manganese dioxide. It will be understood in light of the present disclosure that any suitable cathode materials may be used and the disclosure is not limited in this regard. It will be further understood in light of the present disclosure that suitable cathode materials may vary depending on factors, including those described herein.

[0070] In one or more embodiments, as described herein, the electrochemical cell may include one or more anodes, which may be the first multilayer monolithic electrode 110 or the second electrode 120 of FIGS. 1A-1C, as examples. For further examples, the one or more anodes may be the first multilayer monolithic electrode 510 and the third multilayer monolithic electrode 530 of FIG. 5, or may be the second multilayer monolithic electrode 520. It will be understood in light of the present disclosure that any suitable anode configuration may be used and the disclosure is not limited in this regard.

[0071] The one or more anodes may be made of any suitable material or combination of materials. Suitable anode materials may be selected based on capacity, interfacial kinetics, electrical conductivity, lithium ion diffusivity, particle size, particle surface area, density, porosity, and tortuosity, as examples. Suitable anode materials may include graphite, as examples. For further examples, suitable anode materials may include graphite, lithium titanium oxide, lithium, lithium-alloying materials, intermetallic materials (e.g., alloys), or silicon. In some embodiments, the anode may include a copper foil, which may include a layer of metallic lithium, such as a coating or plating of lithium or of a lithium alloy. It will be understood in light of the present disclosure that any suitable anode materials may be used and the disclosure is not limited in this regard. It will be further understood in light of the present disclosure that suitable anode materials may vary depending on factors, including those described herein.

[0072] Each electrode (for example, the first multilayer monolithic electrode 110 or the second electrode 120 of FIGS. 1A-1C, or the first or second multilayer monolithic electrodes 210, 220 of FIG. 2) may have any suitable thickness. Thickness (te) of each electrode may be described, for example, as a dimension of the electrode (e.g., the electrode 110) along an axis orthogonal to a plane defined by an interface between the electrode and a separator (e.g., the separator 130). Suitable electrode thicknesses may be selected based on balancing desired energy density against desired power density, manufacturability, or mechanical integrity, as a few examples. Suitable electrode thicknesses may include about 0.5 mm, as an example. As further examples, suitable electrode thicknesses may be between 0.05 mm and 1 mm or between 0.2 mm and 0.5 mm. Suitable electrode thicknesses may include greater than 0.01 mm, greater than 0.1 mm, greater than 0.3 mm, greater than 0.5 mm, greater than 1 mm, or greater than 5 mm. It will be understood in light of the present disclosure that any suitable electrode thickness may be used and the disclosure is not limited in this regard. It will be further understood in light of the present disclosure that suitable electrode thicknesses may vary depending on factors, including those described herein.

[0073] Each electrode may have any suitable aspect ratio. As used herein, the aspect ratio of the electrode may be described as the ratio between a cross-sectional area and a thickness of the electrode. In illustrative embodiments according to aspects described herein, the electrode may have a low aspect ratio, relative to typical electrochemical cells. Without wishing to be bound by theory, a lower electrode aspect ratio tends to afford an electrochemical cell with improved energy density (attributable, for example, to a cell with fewer non-active materials) and reduced power density (attributable, for example, to a cell with reduced ion transport capability).

[0074] Suitable electrode aspect ratios may be selected based on balancing desired energy density against desired power density, manufacturability, or mechanical integrity, as a few examples. Suitable electrode aspect ratios may include, less than about 50:1 (that is, a cross-sectional area of 50 times a thickness), for example. For further examples, suitable electrode aspect ratios may include between 5:1 and 5,000:1 or between 15:1 and 100:1. Suitable electrode aspect ratios may include less than 5,000:1, less than 3,000:1, less than 1,000:1, less than 700:1, less than 500:1, less than 400:1, less than 200:1, less than 100:1, less than 80:1, less than 60:1, less than 50:1, less than 30:1, less than 15:1, or less than 10:1. It will be understood in light of the present disclosure that any suitable electrode aspect ratio may be used and the disclosure is not limited in this regard. It will be further understood in light of the present disclosure that suitable electrode aspect ratio may vary depending on factors, including those described herein.

[0075] Embodiments of the electrochemical cell, as described herein, may include one or more multilayer monolithic electrodes. A multilayer monolithic electrode may be described as having two or more layers (i.e., multilayered) with characteristic differences. Characteristic differences between the layers may include different porosities (e.g., a porous layer and a dense layer, as described herein), different densities, or different electrode materials, as examples. The two or more layers of a multilayer monolithic electrode may be described as integrated into a unitary (i.e., monolithic) electrode. That is to say, the multilayer monolithic electrode may be described as having a seamless interface between one layer of the two or more layers and another layer of the two or more layers.

[0076] Each multilayer monolithic electrode may include multiple layers, including one or more dense layers and one or more porous layers. As an example, a multilayer monolithic electrode may include one dense layer and one porous layer (such as in the first multilayer monolithic electrode 110 shown in FIG. 1A). For another example, a multilayer monolithic electrode may include one dense layer between two porous layers, (such as in the first multilayer monolithic electrode 510 shown in FIG. 5).

[0077] As described herein, the one or more dense layers of the multilayer monolithic electrode may afford improved energy density and limited charge/discharge rate capabilities, while the one or more porous layers may afford improved charge/discharge rate capabilities and limited energy density. The multilayer monolithic electrode, according to aspects described herein, may afford both of improved energy density and improved charge/discharge rate capabilities, or may afford improved charge/discharge rate capabilities with minimal tradeoff in energy density, or may afford improved energy density with minimal tradeoff in charge/discharge rate capabilities. Without wishing to be bound by theory, improved charge/discharge rate of the multilayer monolithic electrode may be supported by penetration of electrolyte into the one or more porous layers (or ion transport in the one or more porous layers). Without wishing to be bound by theory, while the limited energy capacity of an illustrative porous layer may afford relatively brief application of high current, an illustrative dense layer may charge (or discharge) the illustrative porous layer after a high current application has reached the charge/discharge capacity of the porous layer.

[0078] As described herein, the multilayer monolithic electrode may be capable of any suitable pulsed discharge profile, and may be capable of improved pulsed discharge profiles with minimal tradeoff in energy density.

[0079] Suitable pulsed discharge profiles may include any suitable pulse periods. Suitable pulse periods may be between 1 millisecond (ms) and 10 ms, for example. As further examples, suitable pulse periods may be 0.5 ms or greater, 1 ms or greater, 3 ms or greater, 5 ms or greater, 8 ms or greater, or 10 ms or greater. As still further examples, suitable pulse periods may be 15 ms or less, 10 ms or less, 7 ms or less, 5 ms or less, 2 ms or less, or 1 ms or less.

[0080] Suitable pulsed discharge profiles may include any suitable discharge rate. Suitable pulsed discharge rates may include between C/50 and 1C or between C/50 and C/5, as examples. As further examples, suitable pulsed discharge rates may include C/60 or greater, C/50 or greater, C/30 or greater, C/15 or greater, C/5 or greater, or 1C or greater. As still further examples, suitable pulsed discharge rates may include 1C or less, C/5 or less, C/15 or less, C/30 or less, or C/50 or less. [0081] Suitable pulsed discharge profiles may include any suitable duty cycle. Suitable duty cycles may include between 20 % and 70 %, for example. As further examples, suitable duty cycles may include 15% or greater, 20 % or greater, 35 % or greater, 50 % or greater, or 70 % or greater. In still further examples, suitable duty cycles may include 80% or less, 70 % or less, 55 % or less, 40 % or less, or 20 % or less.

[0082] Suitable pulsed discharge profiles may include any suitable total duration. Suitable total durations may include, for example, between 2 seconds and 30 minutes or between 10 seconds and 10 minutes. As further examples, suitable total durations may include 1 second or greater, 5 seconds or greater, 10 seconds or greater, 30 seconds, or greater, 1 minute or greater, 5 minutes or greater, 10 minutes or greater, 20 minutes or greater, or 30 minutes or greater. As yet further examples, suitable total durations may include 60 minutes or less, 30 minutes or less, 15 minutes or less, 10 minutes or less, 5 minutes or less, 1 minute ore less, 30 seconds or less, 10 seconds or less, or 5 seconds or less.

[0083] As described herein, each multilayer monolithic electrode may include one or more dense layers. Without wishing to be bound by theory, the dense layer affords an electrode (and, in turn the electrochemical cell) with improved energy density, which may be attributable, for example, to increased mass and density of electrochemically active material. For another example, and without wishing to be bound by theory, improved energy density may be attributable to reduced inactive materials in the electrochemical cell. However, without wishing to be bound by theory, a dense layer affords limited power density, which may be attributable, for example, to limited ion transfer due to low porosity and high tortuosity.

[0084] Each dense layer may have any suitable porosity. Porosity may be determined, or measured, using any suitable method or technique, such as Mercury Intrusion Porosimetry or Electromechanical Impedance Spectroscopy, for two examples. Suitable dense layer porosities may be selected based on desired energy density or material properties such as particle size, particle shape or particle surface area, as examples. Suitable dense layer porosities may include, for example, about 10 %. For further examples, suitable dense layer porosities may include between 1 % and 30 % or between 5 % and 20 %. Suitable dense layer porosities may include less than 40 %, less than 30 %, less than 25 %, less than 20 %, less than 15 %, less than 10 %, less than 8 %, or less than 5 %. [0085] Each dense layer may have any suitable thickness. Thickness of each dense layer (e.g., ta) may be described, for example, as a dimension of the dense layer (e.g., the dense layer 112) along an axis orthogonal to a plane defined by an interface between the dense layer and a porous layer (e.g., the porous layer 114). As another example, thickness of each dense layer may be described as a dimension of the dense layer along an axis orthogonal to a plane defined by an interface between the electrode (e.g., the electrode 110) and a separator (e.g., the separator 130). Suitable dense layer thicknesses may be selected based on balancing desired energy density against desired power density, manufacturability, or mechanical integrity, as a few examples. Suitable dense layer thicknesses may include about 0.4 mm, as an example. For additional examples, suitable dense layer thicknesses may include between 0.05 mm and 1 mm or between 0.1 mm and 0.5 mm. Suitable dense layer thicknesses may include greater than 0.01 mm, greater than 0.1 mm, greater than 0.3 mm, greater than 0.4 mm, greater than 0.5 mm, greater than 1 mm, or greater than 5 mm. It will be understood in light of the present disclosure that any suitable dense layer thickness may be used and the disclosure is not limited in this regard. It will be further understood in light of the present disclosure that suitable dense layer thicknesses may vary depending on factors, including those described herein.

[0086] Each dense layer may have any suitable thickness relative to a thickness of a respective porous layer. As used herein, the respective porous layer may refer to a porous layer of the same multilayer monolithic electrode as the referent dense layer. That is to say, each multilayer monolithic electrode may have any suitable ratio of dense layer thickness (or total dense layer thickness) to porous layer thickness (or total porous layer thickness). Suitable dense layer thickness may be at least four times greater than the thickness of the respective porous layer, as an example. For another example, suitable dense layer thickness may be between 25 % greater and 100 times greater than the thickness of the respective porous layer or between 2 times greater and 10 times greater than the thickness of the respective porous layer. Suitable dense layer thicknesses may be at least 25 % greater, at least 50 % greater, at least 2 times greater, at least 3 times greater, at least 4 times greater, at least 5 times greater, at least 8 times greater, at least 10 times greater, at least 25 times greater, at least 50 times greater, or at least 100 times greater than the thickness of the respective porous layer. [0087] Each dense layer may be capable of any suitable discharge rate. Suitable dense layer discharge rates may include about 1C, as an example. Suitable dense layer discharge rates may include between C/87, 660 and C/24 or between C/8, 766 and C/4, 383, for example. As further examples, suitable dense layer discharge rates may include C/87, 660 or greater, C/50, 000 or greater, C/10, 000 or greater, C/8, 766 or greater, C/4, 383 or greater, C/1, 000 or greater, C/100 or greater, or C/24 or greater. For still further examples, suitable dense layer discharge rates may include C/24 or less, C/100 or less, C/1, 000 or less, C/4, 383 or less, C/8, 766 or less, C/10, 000 or less, C/50, 000 or less, or C/87, 660 or less. [0088] Each dense layer may be made of any suitable material or combination of materials, as described herein. Suitable dense layer materials may be selected based on capacity, interfacial kinetics, electrical conductivity, particle size, particle surface area, density, porosity, and tortuosity, as examples. In some embodiments, suitable dense layer materials may be selected based on a polarity of a respective electrode. Suitable dense layer materials may be selected, for example, from the list of suitable cathode materials described in the present disclosure. For further examples, suitable dense layer materials may be selected from the list of suitable anode materials described in the present disclosure.

[0089] Any suitable electrode formation process may be used to form each dense layer. Suitable formation processes may be selected based on material properties, particle size, particle surface area, desired electrode thickness, density, porosity, and tortuosity, as examples. In one or more embodiments, suitable dense layer formation processes may include dry-formation processes, for example. As another example, suitable dense layer formation processes may include slurry-formation processes. In some embodiments, formation of the dense layer by dry-formation processes may be preferred, for example, to afford greater density (or reduced porosity) in the dense layer. Without wishing to be bound by theory, relatively denser or relatively thicker dense layers may afford relatively increased energy density (or energy capacity) in the respective electrode, which may afford relatively increased energy density in the electrochemical cell.

[0090] As described herein, each multilayer monolithic electrode may include one or more porous layers. Without wishing to be bound by theory, the porous layer affords an electrode (and, in turn the electrochemical cell) with improved power density, or improved charge/discharge rate capabilities, which may be attributable, for example, to increased ion transport in the electrode via the pores. However, without wishing to be bound by theory, a porous layer may afford limited energy density, which may be attributable, for example, to reduced mass and density of electrochemically active material.

[0091] Each porous layer may be capable of any suitable discharge rate. Suitable porous layer discharge rates may include about 1C, as an example. Suitable porous layer discharge rates may include between C/2 and 20C or between 5C and 15C, as further examples. For still further examples, suitable porous layer discharge rates may include at least 1C or at least 2C.

[0092] Each porous layer may be capable of any suitable pulsed discharge profile. Suitable pulsed discharge profiles may include 7 mA for 6 ms and 1.56 mA current for 24 ms, as an example. Suitable pulsed discharge profiles may include 15 mA for 7 ms, and 4 microamps (uA) for 9 ms as another example.

[0093] Each porous layer may have any suitable porosity. Suitable porous layer porosities may be defined as greater than the porosity of a respective dense layer. As used herein, the respective dense layer may refer to a dense layer of the same multilayer monolithic electrode as the referent porous layer. For example, in reference to FIG. 2, the porous layer 214 of the first multilayer monolithic electrode 210 may have a porosity greater than a porosity of the dense layer 212 of the first multilayer monolithic electrode 210. As another example, in reference to FIG. 5, the first porous layer 514 of the first multilayer monolithic electrode 510 may have a porosity greater than a porosity of the dense layer 512 of the first multilayer monolithic electrode 510. Similarly, the second porous layer 515 may have a porosity greater than the porosity of the dense layer 512. In some embodiments, each porous layer of an electrode with two or more porous layers (for example, each of the first and second porous layers 514, 515 of the first electrode 510) may have the same or approximately the same porosity. Additionally or alternatively, each porous layer of an electrode with two or more porous layers may have different porosities. [0094] Suitable porous layer porosities may be selected based on desired power density, mechanical integrity, or material properties such as particle size, particle shape, or particle surface area, as examples. Suitable porous layer porosities may include, for example, about 40 %. For further examples, suitable porous layer porosities may include between 10 % and 80 % or between 30 % and 50 %. Suitable porous layer porosities may include at least 10 %, at least 15 %, at least 20 %, at least 25 %, at least 30 %, at least 40 %, at least 50 %, at least 60 %, at least 70 %, or at least 80 %.

[0095] Each porous layer may have any suitable porosity relative to the porosity of a respective dense layer. Suitable porous layer porosities may be between 10 % greater and 10 times greater than the porosity of the respective dense layer or between 50 % greater and 4 times greater than the porosity of the respective dense layer, as examples. For further examples, suitable porous layer porosities may be at least 10 % greater, at least 25 % greater, at least 50 % greater, at least 80 % greater, at least 2 times greater, at least 3 times greater, at least 4 times greater, at least 5 times greater, at least 7 times greater, or at least 10 times greater than the porosity of the respective dense layer.

[0096] Each porous layer may have any suitable thickness. Thickness of each porous layer (e.g., T_P) may be described, for example, as a dimension of the porous layer (e.g., the porous layer 114) along an axis orthogonal to a plane defined by an interface between the porous layer and a dense layer (e.g., the dense layer 112). As another example, thickness of each porous layer may be described as a dimension of the porous layer along an axis orthogonal to a plane defined by an interface between the electrode (e.g., the electrode 110) and a separator (e.g., the separator 130). Suitable porous layer thicknesses may be selected based on balancing desired energy density against desired power density, desired capacity for high-current applications, manufacturability, or mechanical integrity, as a few examples. In some embodiments, and as described herein, suitable porous layer thicknesses may preferably be less than a thickness of a respective dense layer. As used herein, the respective dense layer may refer to a dense layer of the same multilayer monolithic electrode as the referent porous layer. That is to say, a dense layer of the same multilayer monolithic electrode as the respective porous layer.

[0097] Suitable porous layer thicknesses may include about 0.1 mm, as an example. For additional examples, suitable porous layer thicknesses may include between 0.005 mm and 0.1 mm or between 0.01 mm and 0.05 mm. Suitable porous layer thicknesses may include greater than 0.001 mm, greater than 0.003 mm, greater than 0.005 mm, greater than 0.008 mm, greater than 0.01 mm, greater than 0.05 mm, greater than 0.08 mm, greater than 0.1 mm, greater than 0.5 mm, or greater than 1 mm. Suitable porous layer thicknesses may additionally or alternatively include less than 1 mm, less than 0.5 mm, less than 0.2 mm, less than 0.1 mm, less than 0.08 mm, less than 0.05 mm, less than 0.02 mm, less than 0.01 mm, or less than 0.005 mm. It will be understood in light of the present disclosure that any suitable porous layer thickness may be used and the disclosure is not limited in this regard. It will be further understood in light of the present disclosure that suitable porous layer thicknesses may vary depending on factors, including those described herein.

[0098] Each porous layer may be made of any suitable material or combination of materials, as described herein. Suitable porous layer materials may be selected based on capacity, interfacial kinetics, lithium ion diffusivity, rechargeability, electrical conductivity, particle size, particle surface area, density, porosity, and tortuosity, as examples. In some embodiments, suitable porous layer materials may be selected based on a polarity of a respective electrode. Suitable porous layer materials may be selected, for example, from the list of suitable cathode materials described in the present disclosure. For further examples, suitable porous layer materials may be selected from the list of suitable anode materials described in the present disclosure. In some embodiments, the material composition of the dense layer may be different than the material composition of the porous layer. For example, the material composition of the porous layer may include materials suitable for a rechargeable, or secondary, battery and the material composition of the dense layer may include materials suitable for a non-rechargeable, or primary, battery. [0099] Any suitable electrode formation process may be used to form each porous layer. Suitable formation processes may be selected based on material properties, particle size, particle surface area, density, porosity, and tortuosity, as examples. In one or more embodiments, suitable porous layer formation processes may include dry-formation processes, for example. As another example, suitable porous layer formation processes may include slurry-formation processes. As still another example, suitable porous layer processes may include use of a porogen, or pore-forming agent, which may be embedded in the electrode during formation and then removed after formation.

[0100] In one or more embodiments, as described herein, the electrochemical cell may include one or more separators, which may each be between electrodes of opposite polarities. That is to say, each of the one or more separators may be disposed or sandwiched between electrodes of opposite polarities, such as between a cathode and an anode and may further be in intimate contact with said electrodes. The one or more separators may each be porous, microporous, perforated, or may include holes for electrolyte to penetrate the separator. Accordingly, each of the one or more separators may facilitate ion transfer within the electrochemical cell because an electrolyte provides a medium for ion transfer.

[0101] The one or more separators may each be made of any suitable material or combination of materials. Suitable separator materials may be selected based on porosity, tortuosity, or mechanical strength, as just a few examples. Suitable separator materials may include, for example polypropylene, polyethylene, Polytetrafluoroethylene (PTFE), cellophane, nylon, polyolefin, microporous membrane, or multilayer microporous membrane (e.g., CELGARD® 2320 Trilayer Microporous Membrane). It will be understood in light of the present disclosure that any suitable separator materials may be used and the disclosure is not limited in this regard. It will be further understood in light of the present disclosure that suitable separator materials may vary depending on factors, including those described herein.

[0102] The one or more separators may each be any suitable thickness. Suitable separator thickness may be selected based on resistance and mechanical strength, as just two examples. Suitable separator thicknesses may include, for example, between 1 micrometer (um) and 100 um or between 1 um and 10 um. Suitable separator thickness may additionally or alternatively include, for example, greater than 1 um, greater than 3 um, greater than 5 um, greater than 8 um, greater than 10 um, greater than 20 um, or greater than 50 um. It will be understood in light of the present disclosure that any suitable separator thickness may be used and the disclosure is not limited in this regard. It will be further understood in light of the present disclosure that suitable separator thicknesses may vary depending on factors, including those described herein.

[0103] In one or more embodiments, as described herein, the electrochemical cell may include an electrolyte. Although not explicitly labeled in the figures, the electrolyte may generally fill at least a portion of any spaces inside the housing not filled by the other components of the electrochemical cell. The electrolyte may facilitate ion transfer between opposite-polarity electrodes, such as between an anode and a cathode. The electrolyte may have an electrical potential. The electrolyte may include any suitable material and may be one or more of, for example, a liquid, a gel, a solid, or a paste. The material composition of the electrolyte may depend on a cell type of the electrochemical cell. The material composition of the electrolyte may include, for example, lithium salt, fluorinated sulfone, or other suitable electrolyte. The electrolyte may include a non-aqueous solution in which a lithium salt (for example, lithium hexafluorophosphate salt) is dissolved in an organic carbonate solvent (such as, for example, mixtures including one or more of ethylene carbonate, dimethyl carbonate, propylene carbonate, diethyl carbonate, or ethyl methyl carbonate). It will be understood in light of the present disclosure that any electrolyte composition may be used and the disclosure is not limited in this regard. It will be further understood in light of the present disclosure that suitable electrolyte compositions may vary depending on factors, including those described herein.

[0104] The electrochemical cell may include a volume not filled by electrolyte (that is, a void). The void may be useful, for example, to avoid overpressure of the enclosure.

[0105] In one or more embodiments, as described herein, the electrochemical cell may be at least partially disposed in a housing. Although not explicitly shown in the figures, the housing may generally enclose the components of the electrochemical cell and contain the electrolyte within the housing. At least portions of at least some components may not be enclosed by the housing. Portions of each of the one or more current collectors may not be enclosed by the housing, as an example.

[0106] The housing may include any suitable material or combination of materials. Suitable housing materials may include aluminum, titanium, stainless steel, nickel, and nickel coated ferrous steels, as examples. In one or more embodiments, the housing may include a polymeric material.

[0107] In some embodiments, the electrochemical cell may have a “case neutral” design. In other words, the housing may float according to the electrolyte potential of the electrochemical cell. To achieve a case neutral design, the electrochemical cell may include one or more current collectors that extend through the housing while being insulated from the housing by a feedthrough insulator.

[0108] In various embodiments, the electrochemical cell may include various insulators (not shown in the figures) to insulate the conductive components (such as the housing, the one or more current collectors, and the one or more multilayer monolithic electrodes, for a few examples) from one another. The insulators may be made of any suitable material or combination of materials. Suitable insulator materials may include, for example, polytetrafluoroethylene (PTFE), polysulfone, glass, and ceramic materials (such as alumina). It will be understood in light of the present disclosure that any suitable insulator materials may be used and the disclosure is not limited in this regard. It will be further understood in light of the present disclosure that suitable insulator materials may vary depending on factors, including those described herein.

[0109] In one or more embodiments, the electrochemical cell may include various electrical connections, such as between conductive components. Such electrical connections may be made by intimate contact between two or more conducting materials. Additionally or alternatively, such electrical connections may be made by welding two or more conducting materials together (e.g., by resistance welding or laser welding). Where conducting materials have at least slightly incompatible metallurgical characteristics (such as in a connection between titanium and copper), a weld interposer (e.g., a vanadium weld interposer) may be used to manage weld stability and strength.

[0110] In one or more embodiments, as described herein, the electrochemical cell may include one or more current collectors. As described in reference to the figures, the one or more current collectors (for example, the current collector 140 shown in FIG. 1A) is electrically connected to the electrode (for example, the first electrode 110) and may be in any suitable position. Suitable current collector positions may be selected based on structural support of the electrode, proximity to one or more reaction zones of the electrode, or ease of manufacturing, as just a few examples. According to aspects of one or more preferred embodiments, each of the one or more current collectors may be electrically connected to the dense layer of the multilayer monolithic electrode.

[0111] Each of the one or more current collectors may include any suitable material or combination of materials. Suitable current collector materials may be selected based on porosity, electrical conductivity, or material compatibility with the electrodes, as a few examples. Suitable current collector materials may include, for example, copper, aluminum, titanium, or stainless steel. Other examples of suitable current collector materials may include alloys, such as aluminum alloys or titanium alloys. Each of the one or more current collectors may be at least partially electrolyte-permeable. Additionally or alternatively, each of the one or more current collectors may be at least partially porous. Electrolyte-permeability or porousness of the one or more current collectors may be useful, for example, to permit the electrolyte to penetrate the current collector. Each of the one or more current collectors additionally or alternatively may be in the form of a mesh or grid, which may be useful, for example, to permit electrolyte to penetrate the one or more current collectors. It will be understood in light of the present disclosure that any suitable current collector materials may be used and the disclosure is not limited in this regard. It will be further understood in light of the present disclosure that suitable current collector materials may vary depending on factors, including those described herein.

ILLUSTRATIVE ASPECTS

[0112] The following is a list of illustrative aspects according to the present disclosure.

[0113] Aspect 1 is an electrochemical cell comprising: an electrode comprising: a dense layer with a porosity of less than 20 %; and a porous layer with a porosity greater than the porosity of the dense layer, the porous layer adjacent and electrically coupled to the dense layer; a current collector electrically coupled to the dense layer; a second electrode; and a separator between the second electrode and the porous layer of the electrode.

[0114] Aspect 2 is the electrochemical cell of aspect 1, wherein the porosity of the dense layer is less than 10 %.

[0115] Aspect 3 is the electrochemical cell of aspect 1, wherein the porosity of the dense layer is less than 5 %.

[0116] Aspect 4 is the electrochemical cell of aspect 1, wherein the porosity of the porous layer is at least 20 %.

[0117] Aspect 5 is the electrochemical cell of aspect 1, wherein the porosity of the porous layer is at least 50 %.

[0118] Aspect 6 is the electrochemical cell of aspect 1, wherein the porosity of the porous layer is at least 50 % greater than the porosity of the dense layer.

[0119] Aspect 7 is the electrochemical cell of aspect 1, wherein the porosity of the porous layer is at least two times the porosity of the dense layer.

[0120] Aspect 8 is the electrochemical cell of aspect 1, wherein the porosity of the porous layer is at least three times the porosity of the dense layer.

[0121] Aspect 9 is the electrochemical cell of aspect 1, wherein the dense layer has a thickness of 0.3 mm or greater.

[0122] Aspect 10 is the electrochemical cell of aspect 1, wherein the dense layer has a thickness of 0.4 mm or greater. [0123] Aspect 11 is the electrochemical cell of aspect 1, wherein the porous layer has a thickness of 0.2 mm or less.

[0124] Aspect 12 is the electrochemical cell of aspect 1, wherein the porous layer has a thickness of 0.1 mm or less.

[0125] Aspect 13 is the electrochemical cell of aspect 1, wherein the dense layer has a thickness at least 50 % greater than a thickness of the porous layer.

[0126] Aspect 14 is the electrochemical cell of aspect 1, wherein the dense layer has a thickness of at least two times a thickness of the porous layer.

[0127] Aspect 15 is the electrochemical cell of aspect 1, wherein the dense layer has a thickness of at least three times a thickness of the porous layer.

[0128] Aspect 16 is the electrochemical cell of aspect 1, wherein a cross-sectional area of the electrode is less than 500 times a thickness of the electrode.

[0129] Aspect 17 is the electrochemical cell of aspect 1, wherein a cross-sectional area of the electrode is less than 100 times a thickness of the electrode.

[0130] Aspect 18 is the electrochemical cell of aspect 1, wherein a cross-sectional area of the electrode is less than 50 times a thickness of the electrode.

[0131] Aspect 19 is the electrochemical cell of aspect 1, wherein the dense layer comprises a dry-formation electrode material.

[0132] Aspect 20 is the electrochemical cell of aspect 1, wherein the current collector comprises one or both of a mesh and a grid.

[0133] Aspect 21 is the electrochemical cell of aspect 1, wherein the cell has an energy density of 100 Wh/L or greater.

[0134] Aspect 22 is the electrochemical cell of aspect 1, wherein the cell has an energy density of 300 Wh/L or greater.

[0135] Aspect 23 is the electrochemical cell of aspect 1, wherein the cell has an energy density of 500 Wh/L or greater.

[0136] Aspect 24 is the electrochemical cell of aspect 1, wherein the cell can be pulse- discharged at a discharge rate C/50 or greater, C/20 or greater, or C/5 or greater.

[0137] Aspect 25 is the electrochemical cell of aspect 1, wherein the dense layer of the electrode can be discharged at a discharge rate of C/24 or less, C/4, 383 or less, C/8, 766 or less, or C/87, 660 or less. [0138] Aspect 26 is the electrochemical cell of aspect 1, wherein the porous layer of the electrode can be discharged at a discharge rate of 1C rate or greater, 2C or greater, or 5C or greater.

[0139] Aspect 27 is an electrochemical cell comprising: a cathode comprising: a cathode dense layer with a porosity of less than 20 %; and a cathode porous layer with a porosity greater than the porosity of the cathode dense layer, the cathode porous layer adjacent and electrically coupled to the cathode dense layer; a cathode current collector electrically coupled to the cathode dense layer; an anode comprising: an anode dense layer with a porosity of less than 20 %; and an anode porous layer with a porosity greater than the porosity of the anode dense layer, the anode porous layer adjacent and electrically coupled to the anode dense layer; an anode current collector electrically coupled to the anode dense layer; and a separator between the anode porous layer and the cathode porous layer.

[0140] Aspect 28 is the electrochemical cell of aspect 27, wherein the porosity of one or both of the cathode dense layer or the anode dense layer is less than 10 %.

[0141] Aspect 29 is the electrochemical cell of aspect 27, wherein the porosity of one or both of the cathode dense layer or the anode dense layer is less than 5 %.

[0142] Aspect 30 is the electrochemical cell of aspect 27, wherein the porosity of one or both of the cathode porous layer or the anode porous layer is at least 20 %.

[0143] Aspect 31 is the electrochemical cell of aspect 27, wherein the porosity of one or both of the cathode porous layer or the anode porous layer is at least 50 %.

[0144] Aspect 32 is the electrochemical cell of aspect 27, wherein the porosity of the cathode porous layer is at least 50 % greater than the porosity of the cathode dense layer, or wherein the porosity of the anode porous layer is at least 50 % greater than the porosity of the anode dense layer, or both.

[0145] Aspect 33 is the electrochemical cell of aspect 27, wherein the porosity of the cathode porous layer is at least two times the porosity of the cathode dense layer, or wherein the porosity of the anode porous layer is at least two times the porosity of the anode dense layer, or both. [0146] Aspect 34 is the electrochemical cell of aspect 27, wherein the porosity of the cathode porous layer is at least three times the porosity of the cathode dense layer, or wherein the porosity of the anode porous layer is at least three times the porosity of the anode dense layer, or both.

[0147] Aspect 35 is the electrochemical cell of aspect 27, wherein one or both of the cathode dense layer and the anode dense layer has a thickness of 0.3 mm or greater.

[0148] Aspect 36 is the electrochemical cell of aspect 27, wherein one or both of the cathode dense layer and the anode dense layer has a thickness of 0.4 mm or greater.

[0149] Aspect 37 is the electrochemical cell of aspect 27, wherein one or both of the cathode porous layer and the anode porous layer has a thickness of 0.2 mm or less.

[0150] Aspect 38 is the electrochemical cell of aspect 27, wherein one or both of the cathode porous layer and the anode porous layer has a thickness of 0.1 mm or less.

[0151] Aspect 39 is the electrochemical cell of aspect 27, wherein the cathode dense layer has a thickness at least 50 % greater than a thickness of the cathode porous layer, or wherein the anode dense layer has a thickness at least 50 % greater than a thickness of the anode porous layer, or both.

[0152] Aspect 40 is the electrochemical cell of aspect 27, wherein the cathode dense layer has a thickness of at least two times a thickness of the cathode porous layer, or wherein the anode dense layer has a thickness of at least two times a thickness of the anode porous layer, or both.

[0153] Aspect 41 is the electrochemical cell of aspect 27, wherein the cathode dense layer has a thickness of at least three times a thickness of the cathode porous layer, or wherein the anode dense layer has a thickness of at least three times a thickness of the anode porous layer, or both.

[0154] Aspect 42 is the electrochemical cell of aspect 27, wherein a cross-sectional area of the cathode is less than 500 times a thickness of the cathode, or wherein a cross-sectional area of the anode is less than 500 times a thickness of the anode, or both.

[0155] Aspect 43 is the electrochemical cell of aspect 27, wherein a cross-sectional area of the cathode is less than 100 times a thickness of the cathode, or wherein a cross-sectional area of the anode is less than 100 times a thickness of the anode, or both. [0156] Aspect 44 is the electrochemical cell of aspect 27, wherein a cross-sectional area of the cathode is less than 50 times a thickness of the cathode, or wherein a cross-sectional area of the anode is less than 50 times a thickness of the anode, or both.

[0157] Aspect 45 is the electrochemical cell of aspect 27, wherein one or both of the cathode dense layer and the anode dense layer comprises a dry-formation electrode material.

[0158] Aspect 46 is the electrochemical cell of aspect 27, wherein one or both of the cathode current collector and the anode current collector comprises one or both of a mesh and a grid.

[0159] Aspect 47 is the electrochemical cell of aspect 27, wherein the cell has an energy density of 100 Wh/L or greater.

[0160] Aspect 48 is the electrochemical cell of aspect 27, wherein the cell has an energy density of 300 Wh/L or greater.

[0161] Aspect 49 is the electrochemical cell of aspect 27 wherein the cell has an energy density of 500 Wh/L or greater.

[0162] Aspect 50 is the electrochemical cell of aspect 27, wherein the cell can be pulse- discharged at a discharge rate C/50 or greater, C/20 or greater, or C/5 or greater.

[0163] Aspect 51 is the electrochemical cell of aspect 27, wherein the cathode dense layer of the electrode can be discharged at a discharge rate of C/24 or less, C/4, 383 or less, C/8, 766 or less, or C/87, 660 or less; or wherein the anode dense layer of the electrode can be discharged at a discharge rate of C/24 or less, C/4, 383 or less, C/8, 766 or less, or C/87, 660 or less; or both.

[0164] Aspect 52 is the electrochemical cell of aspect 27, wherein the cathode porous layer of the electrode can be discharged at a discharge rate of 1C rate or greater, 2C or greater, or 5C or greater; or wherein the anode porous layer of the electrode can be discharged at a discharge rate of 1C rate or greater, 2C or greater, or 5C or greater; or both. [0165] Aspect 53 is an electrochemical cell comprising: a plurality of unit cells, each unit cell comprising: a cathode comprising: a cathode dense layer with a porosity of less than 20 %; and a cathode porous layer with a porosity greater than the porosity of the cathode dense layer, the cathode porous layer adjacent and electrically coupled to the cathode dense layer; a cathode current collector electrically coupled to the cathode dense layer; an anode comprising: an anode dense layer with a porosity less than 20 %; and an anode porous layer with a porosity greater than the porosity of the anode dense layer, the anode porous layer adjacent and electrically coupled to the anode dense layer; an anode current collector electrically coupled to the anode dense layer; and a separator between the cathode porous layer and the anode porous layer.

[0166] Aspect 54 is the electrochemical cell of aspect 53, wherein the cathode current collector of one of the plurality of unit cells is the cathode current collector of another of the plurality of unit cells, or wherein the anode current collector of one of the plurality of unit cells is the anode current collector of another of the plurality of unit cells, or both. [0167] Aspect 55 is the electrochemical cell of aspect 53, wherein the cathode of one of the plurality of unit cells is the cathode of another of the plurality of unit cells, or wherein the anode of one of the plurality of unit cells is the anode of another of the plurality of unit cells, or both.

[0168] It should also be noted that, as used in this specification and the appended claims, the phrase “configured” describes a system, apparatus, or other structure that is constructed to perform a particular task or adopt a particular configuration. The word “configured” can be used interchangeably with similar words such as “arranged,” “constructed,” “manufactured,” and the like.

[0169] It should further be noted that, as used in this specification and the appended claims, reference to numbers of electrodes is merely for the purpose of distinguishing between electrodes and does not necessarily limit the number of electrodes.

[0170] All publications and patent applications in this specification are indicative of the level of ordinary skill in the art to which this technology pertains. All publications and patent applications are herein incorporated by reference to the same extent as if each individual publication or patent application was specifically and individually indicated by reference. In the event that any inconsistency exists between the disclosure of the present application and the disclosure(s) of any document incorporated herein by reference, the disclosure of the present application shall govern.

[0171] This application is intended to cover adaptations or variations of the present subject matter. It is to be understood that the above description is intended to be illustrative, and not restrictive, and the claims are not limited to the illustrative embodiments as set forth herein.

Claims

WHAT IS CLAIMED IS:

1. An electrochemical cell comprising: a cathode comprising: a cathode dense layer with a porosity of less than 20 %; and a cathode porous layer with a porosity greater than the porosity of the cathode dense layer, the cathode porous layer adjacent and electrically coupled to the cathode dense layer; a cathode current collector electrically coupled to the cathode dense layer; an anode comprising: an anode dense layer with a porosity of less than 20 %; and an anode porous layer with a porosity greater than the porosity of the anode dense layer, the anode porous layer adjacent and electrically coupled to the anode dense layer; an anode current collector electrically coupled to the anode dense layer; and a separator between the anode porous layer and the cathode porous layer.

2. The electrochemical cell of claim 1, wherein the porosity of one or both of the cathode dense layer or the anode dense layer is less than 10 %.

3. The electrochemical cell of any one of the preceding claims, wherein the porosity of one or both of the cathode porous layer or the anode porous layer is at least 20 %.

4. The electrochemical cell of any one of the preceding claims, wherein the porosity of the cathode porous layer is at least 50 % greater than the porosity of the cathode dense layer, or wherein the porosity of the anode porous layer is at least 50 % greater than the porosity of the anode dense layer, or both.

5. The electrochemical cell of any one of the preceding claims, wherein the porosity of the cathode porous layer is at least two times the porosity of the cathode dense layer, or wherein the porosity of the anode porous layer is at least two times the porosity of the anode dense layer, or both.

6. The electrochemical cell of any one of the preceding claims, wherein one or both of the cathode dense layer and the anode dense layer has a thickness of 0.3 mm or greater.

7. The electrochemical cell of any one of the preceding claims, wherein one or both of the cathode porous layer and the anode porous layer has a thickness of 0.2 mm or less.

8. The electrochemical cell of any one of the preceding claims, wherein the cathode dense layer has a thickness at least 50 % greater than a thickness of the cathode porous layer, or wherein the anode dense layer has a thickness at least 50 % greater than a thickness of the anode porous layer, or both.

9. The electrochemical cell of any one of the preceding claims, wherein the cathode dense layer has a thickness of at least two times a thickness of the cathode porous layer, or wherein the anode dense layer has a thickness of at least two times a thickness of the anode porous layer, or both.

10. The electrochemical cell of any one of the preceding claims, wherein a cross- sectional area of the cathode is less than 100 times a thickness of the cathode, or wherein a cross-sectional area of the anode is less than 100 times a thickness of the anode, or both.

11. The electrochemical cell of any one of the preceding claims, wherein one or both of the cathode current collector and the anode current collector comprises one or both of a mesh and a grid.

12. The electrochemical cell of any one of the preceding claims, wherein the cell has an energy density of 100 Wh/L or greater.

13. The electrochemical cell of any one of the preceding claims, wherein the cell can be pulse-discharged at a discharge rate C/50 or greater, C/20 or greater, or C/5 or greater.

14. The electrochemical cell of any one of the preceding claims, wherein the cathode dense layer of the electrode can be discharged at a discharge rate of C/24 or less, C/4, 383 or less, C/8, 766 or less, or C/87, 660 or less; or wherein the anode dense layer of the electrode can be discharged at a discharge rate of C/24 or less, C/4, 383 or less, C/8, 766 or less, or C/87, 660 or less; or both.

15. The electrochemical cell of any one of the preceding claims, wherein the cathode porous layer of the electrode can be discharged at a discharge rate of 1C rate or greater, 2C or greater, or 5C or greater; or wherein the anode porous layer of the electrode can be discharged at a discharge rate of 1C rate or greater, 2C or greater, or 5C or greater; or both.