High-speed production of thick cathode electrodes for battery systems for electric vehicles

Abstract

A vehicle includes: an electric motor; and a battery pack electrically coupled to the electric motor, where the battery pack comprises an electrochemical cell comprising: a cathode; an anode; and an electrolyte between the cathode and the anode; wherein the cathode includes a plurality of cathode voxel layers, where each cathode voxel layer includes a plurality of cathode voxels, and the plurality of cathode voxel layers are disposed on the cathode current collector, and where the plurality of cathode voxel layers have a total thickness of 20 [mu] m to 500 [mu] m.

Description

Technical Field

[0001] The present disclosure relates to battery cell technology, and more particularly to thick cathodes for electrochemical battery cells for electric vehicles. Background Art

[0002] High-voltage electrical systems are increasingly being used to power on-vehicle functions for mobile and stationary systems. For example, in motor vehicles, the demand to improve fuel economy and reduce emissions has led to the development of advanced electric vehicles (EVs). EVs rely on a rechargeable energy storage system (RESS), which typically includes one or more high-voltage battery packs and an electric drivetrain to deliver power from the battery to the wheels. Depending on the power requirements of a given application, the battery pack can include any number of interconnected battery modules. Each battery module includes a collection of electrochemically coupled battery cells. The battery pack is configured to provide a direct current (DC) output voltage at a level suitable for powering a coupled electrical and / or mechanical load (such as an electric motor).

[0003] A battery cell includes an anode, a cathode, an electrolyte composition, and an optional separator. The battery cell can operate in a charging mode to receive electrical energy. The battery cell can operate in a discharging mode to provide electrical energy. The battery cell can operate through charge and discharge cycles, where the battery first receives and stores electrical energy and then provides electrical energy to a connected system. In a vehicle that uses electrical energy to provide power, the vehicle's battery cells can be charged and then the vehicle can travel for a period of time using the stored electrical energy to generate power. The cathode is one of the key components responsible for the electrochemical reactions that occur during charging and discharging. Modern automotive high-voltage battery packs benefit from high-energy density cathodes to improve overall performance and range.

[0004] There is a continuing need for improved cathodes and methods for fabricating cathodes for electrochemical battery cells. Summary of the Invention

[0005] In one aspect, a vehicle is provided. The vehicle includes an electric motor and a battery pack electrically coupled to the electric motor, where the battery pack includes electrochemical battery cells. The electrochemical battery cells include a cathode, an anode, and an electrolyte located between the cathode and the anode. The cathode includes a plurality of cathode voxel layers. Each cathode voxel layer includes a plurality of cathode voxels. The plurality of cathode voxel layers are disposed on a cathode current collector. The plurality of cathode voxel layers have a total (dry) thickness of 20 micrometers (μm) to 500 μm.

[0006] In another embodiment, the plurality of cathode voxel layers have a total (dry) thickness of 30 μm to 250 μm.

[0007] In another embodiment, each cathode voxel layer of the plurality of cathode voxel layers independently has a thickness of 10 μm to 120 μm.

[0008] In another embodiment, the plurality of cathode voxel layers includes a first plurality of cathode voxel layers disposed on a cathode current collector and a second plurality of cathode voxel layers disposed on the first plurality of cathode voxel layers. Each cathode voxel layer in the first plurality of cathode voxel layers independently has a thickness of 10 μm to 20 μm, and each cathode voxel layer in the second plurality of cathode voxel layers independently has a thickness of 20 μm to 30 μm.

[0009] In another embodiment, a cathode is prepared by providing a donor foil, providing a carrier substrate disposed adjacent to the donor foil, providing a current collector defined by an X-Y plane, and activating an optical system to generate a laser beam passing through the donor foil and the carrier substrate to generate a first plurality of cathode voxels. The first plurality of voxels is collected on the current collector to form one or more first cathode voxel layers. The optical system is activated to generate a laser beam passing through the donor foil and the carrier substrate to generate a second plurality of cathode voxels, and the second plurality of cathode voxels is collected on the one or more first cathode voxel layers to form one or more second cathode voxel layers.

[0010] In another embodiment, the cathode is further prepared by curing one or more first cathode voxel layers before forming one or more second cathode voxel layers.

[0011] In another embodiment, the first plurality of cathode voxels includes a first group of cathode voxels and a second group of cathode voxels, and the second plurality of cathode voxels includes a third group of cathode voxels and a fourth group of cathode voxels. The first group of cathode voxels is spaced apart from the second group of cathode voxels along the X-Y plane, or the first group of cathode voxels at least partially overlaps the second group of cathode voxels along the X-Y plane. The third group of cathode voxels is spaced apart from the fourth group of cathode voxels along the X-Y plane, or the third group of cathode voxels at least partially overlaps the fourth group of cathode voxels along the X-Y plane.

[0012] In another embodiment, the first group of cathode voxels has a first thickness in the Z direction perpendicular to the X-Y plane, the second group of cathode voxels has a second thickness in the Z direction perpendicular to the X-Y plane, the third group of cathode voxels has a third thickness in the Z direction perpendicular to the X-Y plane, and the fourth group of cathode voxels has a fourth thickness in the Z direction perpendicular to the X-Y plane. The first thickness is greater than the second thickness, and the third thickness is greater than the fourth thickness.

[0013] On the other hand, an electrochemical cell unit is provided. The electrochemical cell unit includes a cathode, an anode, and an electrolyte disposed between the cathode and the anode. The cathode includes a plurality of cathode voxel layers, wherein each cathode voxel layer includes a plurality of cathode voxels, and the plurality of cathode voxel layers are disposed on a cathode current collector. The total (dry) thickness of the plurality of cathode voxel layers is 20 μm to 500 μm.

[0014] In another embodiment of the electrochemical cell unit, the plurality of cathode voxel layers have a total (dry) thickness of 30 μm to 250 μm.

[0015] In another embodiment of the electrochemical cell unit, each of the plurality of cathode voxel layers independently has a thickness of 10 μm to 120 μm.

[0016] In another embodiment of the electrochemical cell unit, the plurality of cathode voxel layers include a first plurality of cathode voxel layers disposed on a cathode current collector and a second plurality of cathode voxel layers disposed on the first plurality of cathode voxel layers. Each of the cathode voxel layers in the first plurality of cathode voxel layers independently has a thickness of 10 μm to 20 μm. Each of the cathode voxel layers in the second plurality of cathode voxel layers independently has a thickness of 20 μm to 30 μm.

[0017] In another embodiment of the electrochemical cell unit, a cathode is prepared by providing a donor foil; providing a carrier substrate disposed adjacent to the donor foil; providing a current collector defined by an X-Y plane; and activating an optical system to generate a laser beam passing through the donor foil and the carrier substrate to generate a first plurality of cathode voxels. The first plurality of voxels are collected on the current collector to form one or more first cathode voxel layers. The optical system is activated to generate a laser beam passing through the donor foil and the carrier substrate to generate a second plurality of cathode voxels, and the second plurality of cathode voxels are collected on the one or more first cathode voxel layers to form one or more second cathode voxel layers.

[0018] In another embodiment of the electrochemical cell unit, the first plurality of cathode voxels include a first group of cathode voxels and a second group of cathode voxels, and the second plurality of cathode voxels include a third group of cathode voxels and a fourth group of cathode voxels. The first group of cathode voxels is spaced apart from the second group of cathode voxels along the X-Y plane, or the first group of cathode voxels at least partially overlaps the second group of cathode voxels along the X-Y plane. The third group of cathode voxels is spaced apart from the fourth group of cathode voxels along the X-Y plane, or the third group of cathode voxels at least partially overlaps the fourth group of cathode voxels along the X-Y plane.

[0019] In another embodiment of the electrochemical cell unit, the first group of cathode voxels has a first thickness in the Z direction perpendicular to the X-Y plane, the second group of cathode voxels has a second thickness in the Z direction perpendicular to the X-Y plane, the third group of cathode voxels has a third thickness in the Z direction perpendicular to the X-Y plane, and the fourth group of cathode voxels has a fourth thickness in the Z direction perpendicular to the X-Y plane. The first thickness is greater than the second thickness, and the third thickness is greater than the fourth thickness.

[0020] On the other hand, a method of preparing a cathode for an electrochemical cell unit for an electric vehicle is provided. The electrochemical cell unit includes a cathode, an anode, and an electrolyte disposed between the cathode and the anode. The cathode is prepared by providing a donor foil; providing a carrier substrate disposed adjacent to the donor foil; providing a current collector defined by an X-Y plane; and activating an optical system to generate a laser beam passing through the donor foil and the carrier substrate to generate a first set of a plurality of cathode voxels. The first plurality of voxels are collected on the current collector to form one or more first cathode voxel layers. The optical system is activated to generate a laser beam passing through the donor foil and the carrier substrate to generate a second plurality of cathode voxels, and the second plurality of cathode voxels are collected on one or more first cathode voxel layers to form one or more second cathode voxel layers. The one or more first cathode voxel layers and the one or more second cathode voxel layers have a total (dry) thickness of 20 μm to 500 μm.

[0021] In an embodiment of the method, the one or more first cathode voxel layers and the one or more second cathode voxel layers have a total (dry) thickness of 30 μm to 250 μm.

[0022] In another embodiment of the method, each of the one or more first cathode voxel layers independently has a thickness of 10 μm to 120 μm.

[0023] In another embodiment of the method, the first plurality of cathode voxels includes a first set of cathode voxels and a second set of cathode voxels, and the second plurality of cathode voxels includes a third set of cathode voxels and a fourth set of cathode voxels. The first set of cathode voxels is spaced apart from the second set of cathode voxels along the X-Y plane, or the first set of cathode voxels at least partially overlaps the second set of cathode voxels along the X-Y plane. The third set of cathode voxels is spaced apart from the fourth set of cathode voxels along the X-Y plane, or the third set of cathode voxels at least partially overlaps the fourth set of cathode voxels along the X-Y plane.

[0024] In another embodiment of the method, the first set of cathode voxels has a first thickness in the Z direction perpendicular to the X-Y plane, the second set of cathode voxels has a second thickness in the Z direction perpendicular to the X-Y plane, the third set of cathode voxels has a third thickness in the Z direction perpendicular to the X-Y plane, and the fourth set of cathode voxels has a fourth thickness in the Z direction perpendicular to the X-Y plane. The first thickness is greater than the second thickness, and the third thickness is greater than the fourth thickness.

[0025] The above and other features and advantages of the present disclosure will become apparent when the following detailed description is read in conjunction with the accompanying drawings. Brief Description of the Drawings

[0026] Other features, advantages, and details appear only by way of example in the following detailed description, which refers to the accompanying drawings, in which:

[0027] Figure 1 is a vehicle configured according to one or more embodiments;

[0028] Figure 2A is a schematic diagram of an eLIFT system for preparing a cathode according to one or more embodiments;

[0029] Figure 2B is according to one or more embodiments Figure 1 a part of the eLIFT system and a schematic diagram of the resulting cathode voxel layer;

[0030] Figure 3A is a schematic diagram of an exemplary cathode voxel layer according to one or more embodiments;

[0031] Figure 3B is a schematic diagram of an exemplary cathode voxel layer according to one or more embodiments;

[0032] Figure 3C is a schematic diagram of an exemplary cathode voxel layer according to one or more embodiments;

[0033] Figure 3D is a schematic diagram of an exemplary cathode voxel layer according to one or more embodiments;

[0034] Figure 3E is a schematic diagram of an exemplary cathode voxel layer according to one or more embodiments;

[0035] Figure 3F is a schematic diagram of an exemplary cathode voxel layer according to one or more embodiments;

[0036] Figure 3G is a schematic diagram of an exemplary cathode voxel layer according to one or more embodiments;

[0037] Figure 3H is a schematic diagram of an exemplary cathode voxel layer according to one or more embodiments;

[0038] Figure 4 is a schematic diagram of a part of the eLIFT system and the resulting multiple cathode voxel layers according to one or more embodiments;

[0039] Figure 5 is a simplified configuration of an electrochemical cell unit of a battery pack according to one or more embodiments;

[0040] Figure 6A is a topographic map showing the roughness (top) and thickness distribution (bottom) of a single cathode voxel layer formed by an eLIFT cathode system;

[0041] Figure 6BIs a topographical map showing the roughness (top) and thickness distribution (bottom) of two cathode voxel layers formed by an eLIFT cathode system;

[0042] Figure 7 Is a graph of the roughness (micrometers, μm) of a cathode prepared by an eLIFT cathode system versus the roughness (S) values (Sq, Sp, Sv, Sz, and Sa);

[0043] Figure 8 Is a graph of the discharge capacity (milliamperes-hour per square centimeter, mAh / cm2) of an electrochemical cell unit versus the number of cycles (C), where the electrochemical cell unit includes a cathode prepared by an eLIFT cathode system or a comparative cathode prepared by a wet slurry coating method;

[0044] Figure 9A Is a graph of the fluorine signal intensity (counts, cps) versus distance (micrometers, μm), which is determined by averaging randomly selected 5 positions through electron probe microanalysis (EPMA) on an 85-μm thick cathode layer prepared by an eLIFT cathode system according to one or more embodiments;

[0045] Figure 9B Is a graph of the fluorine signal intensity (cps) versus distance (μm), which is determined by averaging randomly selected 5 positions through electron probe microanalysis (EPMA) on a 175-μm thick cathode layer prepared by an eLIFT cathode system according to one or more embodiments; and

[0046] Figure 9C Is a graph of the fluorine signal intensity (cps) versus distance (μm), which is determined by averaging randomly selected 5 positions through electron probe microanalysis (EPMA) on a 190-μm thick comparative cathode layer prepared by a wet slurry coating method. Detailed Description

[0047] The following description is merely exemplary in nature and is not intended to limit the present disclosure and its application or uses.

[0048] The present disclosure applies the electrode laser-induced forward transfer (eLIFT) process and eLIFT formulations to produce high-energy density cathodes for electrochemical cell units in the automotive industry. The eLIFT printing process uses a combination of eLIFT printing parameters and combines with adjusting the density of the cathode formulation to produce surface geometries and rough patterns. As provided herein, the cathode includes a plurality of cathode voxel layers, where each cathode voxel layer includes a plurality of cathode voxels such that the plurality of cathode voxel layers have a total (dry) thickness of 20 to 500 micrometers (μm). Since the eLIFT electrode product can produce a unique surface geometry through a customized combination, the eLIFT electrode product can be easily detected by a profilometer-microscope method.

[0049] These unique combinations enable one to control the surface geometry according to printer parameters, material density, voxel overlap, and gradient layers, to a much higher degree than in roll-to-roll methods. Other conventional methods such as roll-to-roll (R2R) have difficulty achieving such architectures with high reproducibility. In addition, due to the inherent process limitations on material properties (such as viscosity and particle size), many electrode materials are difficult to print, so other additive manufacturing processes (such as extrusion or inkjet printing) make it difficult to fabricate battery electrodes.

[0050] According to one aspect, a vehicle is provided that includes an electric motor and a battery pack electrically coupled to the electric motor. The battery pack includes electrochemical cell units, which will be described in further detail herein, where the electrochemical cell units include a cathode, an anode, and an electrolyte disposed between the cathode and the anode. The cathode includes a plurality of cathode voxel layers, where the cathode voxel layers are disposed on a cathode current collector to have a total (dry) thickness of 20 to 500 micrometers (μm).

[0051] According to an exemplary embodiment, the vehicle is generally designated as 10 in Figure 1 which. The vehicle 10 is shown in the form of an automobile having a body 12. The body 12 includes a passenger compartment 14 within which a steering wheel, front seats, and rear passenger seats (not shown separately) are arranged. A plurality of components may be arranged within the body 12, including, for example, an electric motor 16 (shown by a projection under the front hood). The electric motor 16 is shown only for ease of illustration and discussion. It should be understood that the configuration, location, size, arrangement, etc. of the electric motor 16 are not meant to be particularly limited, and all such configurations (including multi-motor configurations) are within the scope of this disclosure.

[0052] The electric motor 16 is powered by a battery pack 18 (shown by a projection near the rear of the vehicle 10). The battery pack 18 is shown only for ease of illustration and discussion. It should be understood that the configuration, location, size, arrangement, etc. of the battery pack 18 are not meant to be particularly limited, and all such configurations (including split configurations) are within the scope of this disclosure. Additionally, while the embodiments are discussed in the context of a battery pack 18 configured for the electric motor 16 of the vehicle 10, the aspects described herein can be similarly incorporated in any system (vehicle, building, etc.) having an energy storage system (such as one or more battery packs or modules), and all such configurations and applications are within the scope of this disclosure.

[0053] It should be understood that the vehicle can be any one of a variety of different types of automobiles, such as sedans, vans, trucks, or sport utility vehicles (SUVs), and can be two-wheel drive (2WD) (i.e., rear-wheel drive or front-wheel drive), four-wheel drive (4WD), or all-wheel drive (AWD) and / or various other types of vehicles. In some embodiments, the transportation means can be a train, a truck, a ship, an airplane, and / or one or more other types of transportation means.

[0054] As discussed herein, in some embodiments, the battery pack 18 includes a cathode comprising a plurality of cathode voxel layers, wherein each cathode voxel layer comprises a plurality of cathode voxels, and the plurality of cathode voxel layers are disposed on a cathode current collector. Refer to Figure 2A , 2B , FIGS. 3A to 3H and 4 for a more detailed discussion of an example manufacturing process of the cathode.

[0055] In the cathode, the plurality of cathode voxel layers have a total (dry) thickness of 20 to 500 μm. For example, the plurality of cathode voxel layers can have a total (dry) thickness of 20 to 300 μm, 30 to 300 μm, 30 to 250 μm, 30 to 200 μm, 30 to 150 μm, 40 to 200 μm, 50 to 200 μm, 60 to 200 μm, 70 to 200 μm, 80 to 200 μm, or 80 to 190 μm. In some embodiments, each cathode voxel layer in the plurality of cathode voxel layers can independently have a thickness of 10 to 120 μm. For example, each cathode voxel layer in the plurality of cathode voxel layers can independently have a thickness of 10 to 90 μm, 10 to 80 μm, 10 to 70 μm, 10 to 60 μm, 10 to 50 μm, 10 to 40 μm, 10 to 30 μm, 12 to 30 μm, 15 to 30 μm, or 20 to 30 μm.

[0056] Multiple cathode voxel layers can include any number of suitable layers to achieve a desired total thickness. Each cathode voxel layer can have the same or a different thickness from other cathode voxel layers. For example, the multiple voxel layers can include a first plurality of cathode voxel layers disposed on a cathode current collector and a second plurality of cathode voxel layers disposed on the first plurality of cathode voxel layers, wherein each cathode voxel layer in the first plurality of cathode voxel layers has a different thickness from each cathode voxel layer in the second plurality of cathode voxel layers. In some embodiments, the multiple cathode voxel layers can include a first plurality of cathode voxel layers disposed on a cathode current collector and a second plurality of cathode voxel layers disposed on the first plurality of cathode voxel layers, wherein each cathode voxel layer in the first plurality of cathode voxel layers independently has a thickness of 10 to 20 μm, and each cathode voxel layer in the second plurality of cathode voxel layers independently has a thickness of 20 to 30 μm. In some aspects, the cathode voxel layers in the first plurality of cathode voxel layers can each have a thickness less than the thickness of each cathode voxel layer in the second plurality of cathode voxel layers. Any number of variations are envisioned, including three or more different pluralities of cathode voxel layers, wherein the thickness of the cathode voxel layers in each of the pluralities of voxel layers is different from the other cathode voxel layers.

[0057] As described herein, electrode laser-induced forward electrode transfer (eLIFT) can be used to fabricate the cathode of an electrochemical cell unit. A cathode can be fabricated by providing a donor foil, providing a carrier substrate disposed adjacent to the donor foil, providing an optical system, and providing a current collector defined by an X-Y plane. The optical system can be activated to generate a laser beam that passes through the donor foil and the carrier substrate, thereby generating a first plurality of cathode voxels, wherein the first plurality of cathode voxels can be collected on the current collector to form one or more first cathode voxel layers. The optical system can then be activated again to generate a laser beam that passes through the donor foil and the carrier substrate, thereby generating a second plurality of cathode voxels, wherein the second plurality of cathode voxels can be collected on the first plurality of cathode voxels to form one or more second cathode voxel layers. Optionally, one or more additional cathode voxel layers or one or more additional pluralities of cathode voxel layers can be further deposited to form a cathode product.

[0058] Reference Figure 2A and 2B , generally shows an eLIFT cathode system 100. System 100 utilizes laser-induced forward transfer (LIFT) printing technology to deposit component materials. System 100 includes a laser generating source 102 configured to generate a laser beam 108, a donor substrate 112, a donor layer 116 coated or otherwise applied to the surface of the donor substrate 112, and a receiving substrate 124 spaced from the surface of the donor substrate 112, the donor layer 116 being applied to the receiving substrate 124. For convenience, system 100 will be relative to Figure 1The orientation shown is described; however, system 100 is not necessarily limited to this orientation. Thus, donor substrate 112 is herein referred to as having an upper or top surface 123 facing laser source 102 and a lower or bottom surface 122 facing recipient substrate 124 to which donor layer 116 is applied. Donor layer 116 is herein referred to as having an upper or top surface 124 in contact with the lower surface 122 of donor substrate 112 and a lower or bottom surface 126 opposite its upper surface 124. Recipient substrate 124 is referred to as having an upper or top surface 128 facing the lower surface 126 of donor layer 116 thereon.

[0059] Generally, system 100 can be operated to selectively deposit the material of donor layer 116 (referred to herein as donor material) onto the upper surface 128 of recipient substrate 124. More specifically, laser source 102 can generate a laser beam 108 and direct it towards the upper surface 123 of donor substrate 112. Laser beam 108 can be modified, directed, and / or focused, for example, by optical elements such as mirrors, beam splitters, and / or lenses, at the interface between donor substrate 112 and donor layer 116. The operation of system 100 can be controlled by controller 111, including, for example, controlling laser source 102, any other components for modifying, directing, and / or focusing laser beam 108 (such as a scanner having a galvanometer mirror, lenses, etc.), and any components for moving donor substrate 112 and / or recipient substrate 124 (such as a motion platform).

[0060] The controller 111 includes at least one processor 113, a communication bus 115, and a computer-readable storage device or medium 117. The processor 113 performs the computing and control functions of the controller 111. The processor 113 can be any custom or commercially available processor, a central processing unit (CPU), a graphics processing unit (GPU), an auxiliary processor among multiple processors associated with the controller 111, a semiconductor-based microprocessor (in the form of a microchip or chipset), a macroprocessor, any combination thereof, or any device commonly used to execute instructions. The computer-readable storage device or medium 117 can include volatile and non-volatile storage such as, for example, read-only memory (ROM), random access memory (RAM), and keep-alive memory (KAM). KAM is a permanent or non-volatile memory that can be used to store various operating variables when the processor 113 is powered off. The computer-readable storage device or medium 117 can be implemented using any of a variety of known memory devices, such as PROM (programmable read-only memory), EPROM (electric PROM), EEPROM (electrically erasable PROM), flash memory, or any other combination of electrical, magnetic, optical, or memory devices capable of storing data, some of which represents executable instructions used by the controller 111 in controlling the system 100. The bus 115 is used to transfer programs, data, status, and other information or signals between the various components of the system 100. The bus 115 can be any suitable physical or logical means for connecting computer systems and components. This includes, but is not limited to, direct hardwired connections, fiber optics, infrared, and wireless bus technologies.

[0061] The instructions can include one or more separate programs, each program including an ordered list of executable instructions for implementing logical functions. When executed by the processor 113, the instructions receive and process signals, perform logic, computations, methods, and / or algorithms, and generate data based on the logic, computations, methods, and / or algorithms. Although only one controller 111 is shown in FIG. 2, embodiments of the system 100 can include any number of controllers 111 that communicate via any suitable communication medium or combination of communication media and cooperate to process sensor signals, perform logic, computations, methods, and / or algorithms, and generate data.

[0062] The controller 111 can be different from Figure 2AThe embodiments shown. For example, the controller 111 may be coupled to or may utilize one or more remote computer systems and / or other control systems, such as being part of one or more of the above-described devices and systems. It should be understood that although this exemplary embodiment is described in the context of a full-featured computer system, those skilled in the art will recognize that these mechanisms can be distributed as a program product, where one or more types of non-transitory computer-readable signal-bearing media are used to store the program and its instructions and effectuate its distribution, such as a non-transitory computer-readable medium that bears the program and contains computer instructions stored therein for causing a computer processor (such as processor 113) to execute and run the program. Examples of signal-bearing media include recordable media such as floppy disks, hard disks, memory cards, and optical disks, as well as transmission media such as digital and analog communication links. It should be understood that cloud-based storage and / or other technologies may also be utilized in certain embodiments. It is also understood that the computer system of the controller 111 may also be different from Figure 2A the embodiments shown. For example, the computer system of the controller 111 may be coupled to or may utilize one or more remote computer systems and / or other control systems.

[0063] The wavelength of the laser beam 108 can and preferably does substantially match or be similar to the transparency of the donor substrate 112 and the absorption ability of the donor layer 116. With this arrangement, the laser beam 108 can pass through the donor substrate 112 and irradiate the donor layer 116 thereon.

[0064] The portion 130 of the donor layer 116 irradiated by the laser beam 108 can be ejected from the donor layer 116 and controllably deposited on the receiving substrate 124. As used herein, the individual deposited materials are referred to as cathode voxels 118. The pattern of the cathode voxels 118 can be formed by scanning and / or rasterizing the laser beam 108 (such as by a scanner with galvanometer mirrors) and / or by moving the donor substrate 112 and / or the receiving substrate 124 (such as by a motion stage 121). In various embodiments, the laser beam 108 can be scanned over the donor layer 116 at a speed of 20 to 50 meters per second (m / s).

[0065] In various embodiments, prior to operating the laser generating source 102, the lower surface 122 of the donor substrate 112 and / or the lower surface 126 of the donor layer 116 thereon are oriented to be substantially parallel to the upper surface 128 of the receiving substrate 124. Depending on the composition of the donor material, the gap or spacing 140 between the donor layer 116 and the receiving substrate 124 can be between, for example, a fraction of a micron to several millimeters. For example, non-Newtonian ink may require a narrower space 140, while Newtonian ink may allow a wider space 140. In some embodiments, the laser beam 108 is directed to be substantially perpendicular to the lower surface 122 of the donor substrate 112. In other embodiments, the laser beam 108 is directed at an angle to the lower surface 122 of the donor substrate 112 that is not perpendicular.

[0066] In various embodiments, the laser generating source 102 can be configured to pulse the laser beam 108, for example, with a laser repetition rate (i.e., pulse) of several nanoseconds, picoseconds, or femtoseconds. In some embodiments, the laser generating source 102 is configured to produce a continuous wave laser beam 108. The laser beam 108 can be produced at various wavelengths. The laser beam 1108 can be produced with a power of about several milliwatts to several hundred watts.

[0067] The system 100 can be configured to controllably deposit the donor material by controlling various parameters of the system 100. In some embodiments, the system 100 is configured to deposit the cathode voxels 118 to overlap, having a dot per inch of about 5% to about 90%.

[0068] The donor substrate 112 is primarily used to mechanically support the donor layer 116 and can thus be configured to have at least a moderate rigidity relative to the donor material. Since the donor substrate 112 is also preferably substantially transparent to the laser beam 108, suitable materials for the donor substrate 112 can include various glass materials (e.g., for near-infrared and visible wavelengths), quartz or fused quartz (e.g., for ultraviolet wavelengths), or various polymeric materials such as polyethylene terephthalate (PET). The donor substrate 112 can have various cross-sectional thicknesses, such as about 5 to 1000 micrometers (μm).

[0069] The donor layer 116 can be applied to the donor substrate 112 using various techniques. In some embodiments, a thin ink layer including the donor material can be uniformly applied on the lower surface 122 of the donor substrate 112. Exemplary techniques for applying the ink can include, but are not limited to, spin coating, doctor blading, or via a continuous ink supply system, such as a roll-to-roll (R2R) coating system.

[0070] To eject the portion 130 of the donor layer 116 irradiated by the laser beam 108, the ink can include at least one component configured to absorb radiation at the wavelength of the laser beam 108. Alternatively or additionally, non-linear absorption can be facilitated by using femtosecond laser beam pulses. In various embodiments, a thin intermediate (sacrificial) layer can be located between the donor substrate 112 and the donor layer 116, which is configured to absorb radiation at the wavelength of the laser beam 108. The intermediate layer can be, for example, a thin film (e.g., from dozens to hundreds of nanometers) of various metal and polymer materials, which are configured to decompose during deposition to minimize contamination on the receiving substrate 124. In some embodiments, the ink can include an active material, a solvent, and optionally one or more additional materials, such as a binder. In such embodiments, the ink can include an active material between about 5 and 20 weight percent (wt%) and a solvent between 5 and 75 wt%. Non-limiting examples of the active material include, but are not limited to, graphite and carbon black. The donor layer 116 can have different cross-sectional thicknesses, e.g., about 5 to 1000 micrometers (μm).

[0071] The receiving substrate 124 can include one or more materials, including but not limited to various metal materials. In some embodiments, the receiving substrate 124 can include materials similar to those used to produce battery components using various other techniques, such as roll-to-roll (R2R) coating. Non-limiting examples of the receiving substrate 124 include, but are not limited to, copper or its alloys, aluminum or its alloys, and certain polymer substrates. The receiving substrate 124 can have different cross-sectional thicknesses, e.g., about 5 to 1000 micrometers (μm).

[0072] The optical system 102 can generate a laser beam 108 that passes through the donor foil 112 and the cathode material 116 to create a cathode voxel 118, which is received on a current collector 124 that defines an X-Y plane, such as a current collector foil. A plurality of cathode voxels 118 create a cathode voxel layer 120, as Figure 2B shown. Each cathode voxel layer 120 can be created with various different densities, resolutions (e.g., overlap of voxels), depositions, etc.

[0073] Figures 3A to 3H Illustrated are various configurations of cathode voxel layers that can be selectively and independently formed in each of a plurality of cathode voxel layers. Figure 3A Illustrated is a cathode voxel layer 120a, which includes a series of first cathode voxels 118a without any dilution. Figure 3B Illustrated is a cathode voxel layer 120b, which includes a series of second cathode voxels 118b that are 10 wt% diluted in a solvent. Figure 3CShows a cathode voxel layer 120c, which includes a series of first cathode voxels 118a without any dilution, a series of second cathode voxels 118b containing 10 wt% dilution in a solvent, and a series of third cathode voxels 118c containing 20 wt% dilution in a solvent, wherein these series of cathode voxels 118a, 118b, 118c can be arranged in any suitable configuration. Figure 3D Shows a cathode voxel layer 120d, which includes cathode voxels 118 arranged in rows along the X-Y plane, wherein the cathode voxels 118 are spaced apart from each other by a first distance. Figure 3E Shows a cathode voxel layer 120e, which includes cathode voxels 118 arranged in rows along the X-Y plane, wherein the cathode voxels 118 are spaced apart from each other by a second distance, and the second distance is less than Figure 3D the first distance in Figure 3F Shows a cathode voxel layer 120f, which includes cathode voxels 118 overlapping each other with a first overlap degree. Figure 3G Shows a cathode voxel layer 120g, which includes cathode voxels 118 overlapping each other with a second overlap degree, and the second overlap degree is greater than Figure 3F the first overlap degree in Figure 3H Shows a cathode voxel layer 120h, which includes cathode voxels 118 that at least partially overlap each other, for example, where the overlap degree varies within the cathode voxel layer 120h. Figures 3A to 3H The configurations shown can be used to adjust and control the resolution of each cathode voxel layer in a plurality of voxel layers.

[0074] In some embodiments, the first plurality of cathode voxels can include a first group of cathode voxels and a second group of cathode voxels, and the second plurality of cathode voxels can include a third group of cathode voxels and a fourth group of cathode voxels, where each group of cathode voxels can be the same or different. In some embodiments, the first group of cathode voxels can be spaced apart from the second group of cathode voxels along the X-Y plane, or the first group of cathode voxels can at least partially overlap the second group of cathode voxels along the X-Y plane. In some embodiments, the third group of cathode voxels can be spaced apart from the fourth group of cathode voxels along the X-Y plane, or the third group of cathode voxels can at least partially overlap the fourth group of cathode voxels along the X-Y plane. In some embodiments, the first group of cathode voxels can have a first thickness in the Z direction perpendicular to the X-Y plane, the second group of cathode voxels can have a second thickness in the Z direction perpendicular to the X-Y plane, the third group of cathode voxels can have a third thickness in the Z direction perpendicular to the X-Y plane, the fourth group of cathode voxels can have a fourth thickness in the Z direction perpendicular to the X-Y plane, the first thickness can be greater than the second thickness, and the third thickness can be greater than the fourth thickness.

[0075] In some embodiments, the cathode voxels in each cathode voxel layer can be formed with a specified degree of overlap or no overlap. As described above, in some embodiments, the cathode voxels in the cathode voxel layer can include regions with cathode voxel overlap and regions without overlap. In some embodiments, the cathode voxels can have an overlap degree of 0% (no overlap) to 75%, such as an overlap degree of 15% to 75% or 25% to 75%, but the embodiments are not limited thereto.

[0076] Figure 4 is shown Figure 2B The illustrated eLIFT cathode system is used to prepare a plurality of cathode voxel layers. The embodiment labeled "A" includes four cathode voxel layers to provide a total height of, for example, about 100 μm. The embodiment labeled "B" includes eight cathode voxel layers to provide a total height of, for example, about 200 μm. However, the embodiments are not limited thereto, and any suitable number of cathode voxel layers can be used. For example, the plurality of cathode voxel layers can include 2 to 25 cathode voxel layers, 4 to 20 cathode voxel layers, 4 to 15 cathode voxel layers, or 4 to 10 cathode voxel layers. Additionally, as noted herein, the plurality of cathode voxel layers can be subdivided into two or more groups of voxel layers, such as a first plurality of cathode voxel layers and a second plurality of cathode voxel layers.

[0077] In some embodiments, the cathode can be further prepared by curing one or more first cathode voxel layers before forming one or more second cathode voxel layers thereon. For example, a first plurality of cathode voxels can be collected on a current collector to form one or more first cathode voxel layers, and then one or more first cathode voxel layers can be cured before depositing a second plurality of cathode voxels thereon. In some embodiments, the cathode voxel layer can be cured after each layer is formed, while in other embodiments, the plurality of cathode voxel layers can be cured after adding every 2 - 10 layers, such as every 2 - 6 layers or every 2 - 4 layers. In some embodiments, one or more first cathode layers are cured before one or more second cathode layers are added thereto.

[0078] An electrochemical cell unit is also provided, including a cathode, an anode, and an electrolyte located between the cathode and the anode. The cathode includes a plurality of cathode voxel layers as described herein, wherein each cathode voxel layer includes a plurality of cathode voxels. The plurality of cathode voxel layers are disposed on a cathode current collector such that the plurality of cathode voxel layers have a total (dry) thickness of 20 to 500 μm. The plurality of cathode voxel layers in the electrochemical cell unit are as described herein for the electrochemical cell of a vehicle, and aspects of the electrochemical cell unit described below also apply to the electrochemical cell unit of a vehicle herein.

[0079] Figure 5 is shown according to one or more embodiments a battery pack (e.g. Figure 1Simplified configuration of the electrochemical cell unit of the battery pack 18). As Figure 5 shown, the electrochemical cell unit 200 may include a cathode 202 (i.e., the positive electrode), an anode 204 (i.e., the negative electrode), and an electrolyte 206 located between the cathode 202 and the anode 204. Although only a single electrochemical cell unit 200 is shown for convenience, it should be understood that the battery pack may include any number of cell units required to meet the battery design constraints (e.g., capacity requirements).

[0080] In some embodiments, the active material (also referred to as the electroactive material) of the cathode 202 may include a lithium-containing active material that can sufficiently perform lithium insertion and extraction, alloying and dealloying, and / or plating and stripping while serving as the positive terminal of the electrochemical cell unit 200. The electroactive material of the cathode 202 may include one or more transition metals, such as manganese (Mn), nickel (Ni), cobalt (Co), chromium (Cr), iron (Fe), vanadium (V), or combinations thereof. Exemplary lithium-containing active materials include spinel lithium manganese oxide (LiMn2O4), lithium cobalt oxide (LiCoO2), nickel manganese oxide spinel (Li(Ni 0.5 Mn 1.5 )O2), layered nickel manganese cobalt oxide (having the general formula xLi2MnO3(1-x)LiMO2, where M is composed of any proportion of Ni, Mn, and / or Co). A specific example of the layered nickel manganese oxide spinel is xLi2MnO3(1-x)Li(Ni 1 / 3 Mn 1 / 3 CO 1 / 3 )O2. Other exemplary lithium-containing cathode active materials include Li(Ni 1 / 3 Mn 1 / 3 Co 1 / 3 )O2), LiNiO2, Li x +yMn2-yO4 (LMO, 0 < x < 1 and 0 < y < 0.1), lithium iron polyanion oxides, such as lithium iron phosphate (LiFePO4) or lithium iron fluorophosphate (Li2FePO4F, LFP), or combinations thereof. Other lithium-containing cathode active materials may also be used, such as LiNi x M 1-x O2 (M is composed of any proportion of Al, Co, and / or Mg), LiNi 1-x Co 1-y M x+y O2 or LiMn 1.5-x Ni 0.5-y M x+y O4 (M is composed of any proportion of Al, Ti, Cr, and / or Mg), stable lithium manganese oxide spinel (Li x Mn 2-y M yO4, where M consists of Al, Ti, Cr, and / or Mg in any proportion), lithium nickel cobalt aluminum oxide (e.g., LiNi 0.8 Co 0.15 Al 0.05 O2 or NCA), aluminum-stabilized lithium manganese oxide spinel (LixMn 2-x Al y O4), NCMA (LiNi 1-x-y-z Co x Mn y Al z O2) (where 0.02 ≤ x ≤ 0.20, 0.01 ≤ y ≤ 0.12 and 0.01 ≤ z ≤ 0.08), lithium vanadium oxide (LiV2O5), Li2MSiO4 (where M consists of Co, Fe, and / or Mn in any proportion), high-efficiency nickel manganese cobalt material (HE-NMC, NMC or LiNiMnCoO2), olivine LiMn x Fe (1-x) PO4 (LMFP), etc. or combinations thereof. "Any proportion" means that any element can be present in any amount. In another example, anion substitution can be carried out in the lattice of any example of the lithium transition metal active material to stabilize the crystal structure. For example, any O atom can be replaced by an F atom. In some embodiments, the cathode includes NCM111, NCM 532, NCM 622, NCM 712, NCM 811, NCMA, NCA, LNMO, or combinations thereof. In some embodiments, the cathode includes NCMA.

[0081] In some embodiments, the electrolyte 206 serves as a separator to provide a physical barrier between the cathode 202 and the anode 204. In some embodiments, the electrolyte 206 includes a dendrite blocking layer, one or more interface layers, and / or one or more electrolyte layers (not shown separately). In some embodiments, in addition to providing a physical barrier between the cathode 202 and the anode 204, the electrolyte 206 can also provide a minimum resistance path for the internal passage of lithium ions (and associated anions) during lithium ion cycling to facilitate the function of the electrochemical cell unit 200.

[0082] The electrolyte 206 provides a medium for the conduction of lithium ions between the cathode 202 and the anode 204 through the electrochemical cell unit 200, and can be in the form of a solid, liquid, or gel. In some aspects, the electrolyte 206 can include a non-aqueous liquid electrolyte solution that includes a lithium salt dissolved in a non-aqueous aprotic organic solvent or a mixture of non-aqueous aprotic organic solvents. Non-limiting examples of lithium salts include lithium hexafluorophosphate (LiPF6), lithium perchlorate (LiClO4), lithium tetrachloroaluminate (LiAlCl4), lithium iodide (LiI), lithium bromide (LiBr), lithium thiocyanate (LiSCN), lithium tetrafluoroborate (LiBF4), lithium tetraphenylborate (LiB(C6H5)4), lithium bis(oxalato)borate (LiB(C2O4)2) (LiBOB), lithium difluorooxalate borate (LiBF2(C2O4)), lithium hexafluoroarsenate (LiAsF6), lithium trifluoromethanesulfonate (LiCF3SO3), lithium bis(trifluoromethane)sulfonimide (LiN(CF3SO2)2), lithium bis(fluorosulfonyl)imide (LiN(FSO2)2) (LiSFI), lithium bis(triglyme)trifluoromethanesulfonylimide (Li(G3)(TFSI), lithium bis(trifluoromethanesulfonyl)azanide (LiTFSA), and combinations thereof. Non-limiting examples of non-aqueous aprotic organic solvents include cyclic carbonates (e.g., ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), fluoroethylene carbonate (FEC)), linear carbonates (e.g., dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC)), aliphatic carboxylic acid esters (e.g., methyl formate, methyl acetate, methyl propionate), γ-lactones (e.g., γ-butyrolactone, γ-valerolactone), chain structure ethers (e.g., 1,2-dimethoxyethane, 1,2-diethoxyethane, ethoxymethoxyethane), cyclic ethers (e.g., tetrahydrofuran, 2-methyltetrahydrofuran), 1,3-dioxolane), etc.

[0083] In some embodiments, the electrolyte can be a solid-state electrolyte. The solid-state electrolyte can include one or more solid-state electrolyte particles, which can include one or more polymer-containing particles, oxide-containing particles, sulfide-containing particles, halide-containing particles, borate-containing particles, nitride-containing particles, hydride-containing particles, or combinations thereof. Exemplary solid-state electrolytes include, but are not limited to, LiTi2(PO4)3, LiGe2(PO4)3, Li7La3Zr2O 12 ,Li3xLa 2 / 3 -xTiO3, Li3PO4, Li3N, Li4GeS4, Li 10 GeP2S 12 ,Li2S-P2S5, Li6PS5Cl, Li6PS5Br, Li6PS5I, Li3OCl, Li 2.99 Ba0.005 ClO or combinations thereof.

[0084] In some embodiments, the anode 204 includes an electroactive material, such as a lithium host material that can serve as the negative terminal of the electrochemical cell unit 200. In various aspects, the electroactive material includes lithium and can be lithium metal. In some embodiments, the anode 204 can include an electroactive lithium host material, such as graphite. In some embodiments, the anode 204 can include a conductive material and one or more polymeric binder materials to structurally hold the graphite material together. The negative electrode can contain greater than or equal to about 50% to less than or equal to about 100% electroactive material (such as graphite or a mixture of graphite and lithiated silicon oxide), optionally less than or equal to about 30% conductive material, and the balance binder. For example, in some embodiments, the anode 204 can include an active material that includes graphite particles mixed with a binder material, which can be polyvinylidene fluoride (PVdF), ethylene propylene diene monomer (EPDM), and / or carboxymethyl cellulose (CMC), styrene butadiene rubber (SBR), a compound and / or mixture of CMC and SBR, nitrile butadiene rubber (NBR), lithium polyacrylate (LiPAA), sodium polyacrylate (NaPAA), sodium alginate, lithium alginate, and combinations thereof, as non-limiting examples. Suitable additional conductive materials can include carbon-containing materials and / or conductive polymers. Carbon-containing materials can include, for example, conductive carbon black, conductive acetylene black, acetylene black, carbon black, graphite, graphene, graphene oxide, carbon nanofibers, carbon nanotubes, etc. Examples of conductive polymers include polyaniline, polythiophene, polyacetylene, polypyrrole, etc. In certain aspects, mixtures of these conductive materials can be used.

[0085] In some embodiments, the cathode material or the material used to prepare the cathode can include a solvent, a binder, and / or a slurry stabilizer (not shown separately). Depending on the choice of the cathode active material, the solvent can be selected from known materials. For example, the solvent for the NCMA active material can include N-methyl-2-pyrrolidone (NMP). Other solvents can be used, such as cyclic carbonates (such as ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), fluoroethylene carbonate (FEC)); acyclic (i.e., linear) carbonates (such as dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC)); aliphatic carboxylic acid esters (such as methyl formate, methyl acetate, methyl propionate); γ-lactones (such as γ-butyrolactone, γ-valerolactone); chain structure ethers (such as 1,2-dimethoxyethane, 1,2-diethoxyethane, ethoxymethoxyethane); cyclic ethers (such as tetrahydrofuran, 2-methyltetrahydrofuran, 1,3-dioxolane); or combinations thereof.

[0086] The cathode active material can be mixed with a binder and / or a conductive filler. Suitable binders include polyvinylidene fluoride (PVdF), poly(ethylene oxide) (PEO), ethylene propylene diene monomer (EPDM), carboxymethyl cellulose (CMC), styrene-butadiene rubber (SBR), styrene-butadiene rubber carboxymethyl cellulose (SBR-CMC), polyacrylic acid (PAA), crosslinked polyacrylic acid-polyethyleneimine, polyimide, polyvinyl alcohol (PVA), sodium alginate, combinations thereof or other suitable binders. Examples of conductive fillers are high surface area carbon such as acetylene black and the like. The binder can hold the electrode materials together, and the conductive filler can ensure good electronic conduction between the positive electrode side current collector and the active material particles of the cathode.

[0087] In some embodiments, the electrochemical cell unit can further include a separator (not shown). Exemplary separators include polymer membranes such as polypropylene membranes or coated polypropylene membranes. The separator can include a polyolefin-containing material having the general formula (CH2CH R ) n wherein R is an alkyl group. In some embodiments, the separator can include a single polyolefin or a combination of polyolefins. Examples of polyolefins include polyethylene (PE), polypropylene (PP), polyamide (PA), polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), polyvinyl chloride (PVC), and / or polyacetylene. Examples of other polymeric materials that can be included in or used to form the separator include cellulose, polyimide, copolymers of polyolefin and polyimide, polyethylene coated with poly(4-styrenesulfonic acid lithium), polyetherimide (PEI), bisphenol-acetone dianhydride (BPADA), p-phenylenediamine, poly(m-phenylene isophthalamide) (PMIA), and / or expanded polytetrafluoroethylene-reinforced polyvinylidene fluoride-hexafluoropropylene.

[0088] The current collector for the cathode and / or anode can be any suitable conductive material. For example, the current collector can include copper, nickel, titanium, platinum, gold, silver, magnesium, aluminum, vanadium, alloys thereof, or combinations thereof. The current collector can have a thickness of 10 nanometers (nm) to 1000 nm. For example, the current collector can have a thickness of 10 nm to 500 nm or 50 nm to 400 nm or 100 nm to 400 nm, but the embodiments are not limited thereto.

[0089] There is also provided a method of fabricating a cathode for an electrochemical cell unit for an electric vehicle, wherein the electrochemical cell unit includes a cathode, an anode, and an electrolyte disposed between the cathode and the anode. The method of fabricating the cathode includes providing a donor foil, providing a carrier substrate disposed adjacent to the donor foil, providing an optical system, and providing a current collector defined by an X-Y plane. The optical system is activated to generate a laser beam passing through the donor foil and the carrier substrate, thereby generating a first plurality of cathode voxels, and the first plurality of cathode voxels are collected on the current collector to form one or more first cathode voxel layers. Then the optical system is activated again to generate a laser beam passing through the donor foil and the carrier substrate, thereby generating a second plurality of cathode voxels, and the second plurality of cathode voxels are collected on the one or more first cathode layers to form one or more second cathode voxel layers. The one or more first cathode voxel layers and the one or more second cathode voxel layers have a total (dry) thickness of 20 to 500 μm.

[0090] In some embodiments, the eLIFT system can be used to fabricate a cathode as described herein, including a plurality of cathode voxel layers, at a line speed of 10 meters per minute (m / min) to 60 m / min, 20 m / min to 50 m / min, or 30 m / min to 40 m / min, but the embodiments are not limited thereto.

[0091] In terms of the hardware architecture, the eLIFT system can be partially implemented using a computing device, which can include a processor, a memory, and one or more input and / or output (I / O) device interfaces, which are communicatively coupled via a local interface. The local interface can include, for example but not limited to, one or more buses and / or other wired or wireless connections. The local interface can have additional elements, such as controllers, buffers (caches), drivers, repeaters, and receivers to enable communication, which are omitted for simplicity. In addition, the local interface can include address, control, and / or data connections to enable proper communication between the above components.

[0092] When the computing device is running, the processor can be configured to execute software stored in the memory, transfer data to and from the memory, and overall control the operation of the computing device according to the software. The software in the memory is read in whole or in part by the processor, possibly cached in the processor, and then executed. The processor can be a hardware device for executing software, particularly the software stored in the memory. The processor can be a custom or commercially available processor, a central processing unit (CPU), an auxiliary processor among multiple processors associated with the computing device, a semiconductor-based microprocessor (in the form of a microchip or chipset), or any device generally used for executing software.

[0093] The memory may include volatile memory elements (e.g., any one or combination of random access memories (RAMs, such as DRAM, SRAM, SDRAM, VRAM, etc.)) and / or non-volatile memory elements (e.g., ROM, hard disk drive, CD-ROM, etc.). Additionally, the memory may incorporate electrical, magnetic, optical, and / or other types of storage media. Note that the memory may also have a distributed architecture where various components are located far from each other but can be accessed by the processor.

[0094] The software in the memory may include one or more separate programs, each program including an ordered list of executable instructions for implementing logical functions. System components embodied as software may also be interpreted as source programs, executable programs (object code), scripts, or any other entity that includes a set of instructions to be executed. When built as a source program, the program is translated by compilers, assemblers, interpreters, etc., which may or may not be included in the memory.

[0095] The discharge capacity C of the battery (measured in ampere-hours or Ah) can be evaluated at different currents or, more commonly, at different C-rates. The C-rate is typically used to describe the battery load or the time (in ampere-hours) for battery charging, i.e., charging or discharging C. The unit of the C-rate is ampere A and is the capacity C divided by the time (in hours). A C-rate of 1C means discharging C for 1 hour (ampere-hours). Other C-rates can be adopted to evaluate the discharge capacity, such as C / 2 (discharging for 2 hours), C / 6 (discharging for 6 hours), C / 10 (discharging for 10 hours), etc.

[0096] Examples

[0097] Example 1

[0098] Cathodes with different thicknesses are prepared using the eLIFT process. The cathode material includes NCMA as the active material. A comparative sample is prepared by forming a single cathode voxel layer on the substrate surface, where the cathode voxels are printed with a 75% overlap. A working sample is prepared by forming two cathode voxel layers on the substrate surface, where the cathode voxels are printed with a 75% overlap in each layer. After applying the NCMA active material layer, the cathode material is cured.

[0099] As a comparative sample, Figure 6A is a topographic map showing the surface roughness (top) and thickness profile (bottom) of a single cathode voxel layer formed by the eLIFT cathode system. As a working sample, Figure 6B is a topographic map showing the surface roughness (top) and thickness profile (bottom) of two cathode voxel layers formed by the eLIFT cathode system. The topographic map shows that the surface roughness decreases when multiple cathode voxel layers are used. This further shows that in Figure 7In it, the figure shows a quantified reduction in the surface roughness of the multi-layer working sample "A" compared to the single-layer reference sample "B". Figure 7 Also shown in it are the baseline roughness "C" and the calculated roughness "D" of the single layer.

[0100] Example 2

[0101] A working cathode is prepared using the eLIFT process, where eight cathode layers each with a thickness of 22 microns are printed to provide a cathode active material layer with a total dry thickness of 174 microns. The cathode voxels are printed with an overlap of 75% in each layer. A curing step is performed after every two layers are printed. The cathode material includes NCMA as the active material. The resulting cathode is assembled into an electrochemical cell unit including an anode and an electrolyte.

[0102] A reference cathode is prepared using a wet slurry coating process with NMP as the solvent. The total dry thickness of the resulting cathode layer is 190 microns. The cathode material includes NCMA as the active material. The resulting reference cathode is assembled into a reference electrochemical cell unit including an anode and an electrolyte.

[0103] The discharge capacities of the working electrochemical cell unit and the reference electrochemical cell unit are compared at various discharge rates. Figure 8 Shown are the discharge capacities of the working electrochemical cell unit and the reference electrochemical cell unit at C-rates of C / 20, C / 3, 1C, 2C, and 4C during multiple cycles. At most charge rates, the charge capacity of the working electrochemical cell unit (75% overlap, labeled "E2") exhibits performance comparable to that of the reference electrochemical cell units (prepared by the conventional slurry method, labeled "CE2A" and "CE2B"). It is also noted that after 15 cycles, the second C / 3 cycle of the working electrochemical cell unit shows a smaller decrease in discharge capacity compared to the reference electrochemical cell units.

[0104] Example 3

[0105] A first working cathode is prepared using the eLIFT process, where four cathode layers are printed to provide a cathode active material layer with a total dry thickness of 85 microns. The cathode voxels are printed with an overlap of 75% in each layer. A curing step is performed after every two layers are printed. The cathode material includes NCMA as the active material. The resulting cathode is assembled into an electrochemical cell unit including an anode and an electrolyte.

[0106] A second working cathode is prepared using the eLIFT process, where eight cathode layers are printed to provide a cathode active material layer with a total dry thickness of 175 microns. The cathode voxels are printed with an overlap of 75% in each layer. A curing step is performed after every two layers are printed. The cathode material includes NCMA as the active material. The resulting cathode is assembled into an electrochemical cell unit including an anode and an electrolyte.

[0107] A comparative cathode was prepared using a wet slurry coating process with NMP as the solvent. The total dry thickness of the resulting cathode layer was 190 microns. The cathode material included NCMA as the active material. The resulting comparative cathode was assembled into a comparative electrochemical cell unit including an anode and an electrolyte. The drying rate of the NMP solvent was adjusted to match the conveying speed of 40 m / min of an 8-meter-long dryer.

[0108] Figure 9A and 9B shows electron probe microanalysis (EPMA) cross-sections of the first and second working eLIFT cathode layers, which have a more uniform PVDF (binder) distribution compared to the cathode layers prepared by the wet slurry process in Figure 9C . These results indicate that the cathode has improved mechanical strength and improved cycling durability.

[0109] The terms "a" and "an" do not denote a limitation of quantity, but rather denote the presence of at least one of the referenced item. The term "or" means "and / or" unless the context clearly dictates otherwise. References throughout the specification to "one aspect" mean that a particular element (e.g., a feature, a structure, a step, or a property) described in connection with that aspect is included in at least one aspect described herein, and may or may not be present in other aspects. Additionally, it should be understood that the described elements can be combined in any suitable manner in the various aspects.

[0110] When an element such as a layer, a film, a region, or a substrate is referred to as being "on" another element, it can be directly on the other element or intervening elements may also be present. In contrast, when an element is referred to as being "directly on" another element, no intervening elements are present.

[0111] Unless stated to the contrary herein, all test standards are the latest valid standards as of the filing date of the present application, or, if priority is claimed, the filing date of the earliest priority application in which the test standard appears.

[0112] Unless otherwise defined, technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains.

[0113] Although the foregoing disclosure has been described with reference to exemplary embodiments, those skilled in the art will understand that various changes can be made and equivalents can be substituted for its elements without departing from its scope. Additionally, many modifications can be made to adapt a particular situation or material to the teachings of the disclosure without departing from the essential scope thereof. Accordingly, it is intended that the disclosure not be limited to the particular embodiments disclosed, but that it will include all embodiments falling within its scope.

Claims

1. A vehicle, comprising: An electric motor; And A battery pack electrically coupled to the electric motor, wherein the battery pack includes electrochemical cell units, and the electrochemical cell units include: A cathode; An anode; and An electrolyte located between the cathode and the anode; Wherein, the cathode includes a plurality of cathode voxel layers, each cathode voxel layer includes a plurality of cathode voxels, and the plurality of cathode voxel layers are disposed on a cathode current collector, and Wherein, the plurality of cathode voxel layers have a total thickness of 20 microns to 500 microns.

2. The vehicle according to claim 1, wherein, The plurality of cathode voxel layers have a total thickness of 30 microns to 250 microns; Each cathode voxel layer in the plurality of cathode voxel layers independently has a thickness of 10 microns to 120 microns; or A combination thereof.

3. The vehicle according to claim 1, wherein, The plurality of cathode voxel layers include: A first plurality of cathode voxel layers disposed on the cathode current collector; and A second plurality of cathode voxel layers disposed on the first plurality of cathode voxel layers, Wherein, each cathode voxel layer in the first plurality of cathode voxel layers independently has a thickness of 10 microns to 20 microns, and Wherein, each cathode voxel layer in the second plurality of cathode voxel layers independently has a thickness of 20 microns to 30 microns.

4. An electrochemical cell unit, comprising: A cathode; An anode; And An electrolyte located between the cathode and the anode; Wherein, the cathode includes a plurality of cathode voxel layers, each cathode voxel layer includes a plurality of cathode voxels, and the plurality of cathode voxel layers are disposed on a cathode current collector, and Wherein, the plurality of cathode voxel layers have a total thickness of 20 microns to 500 microns.

5. The electrochemical cell unit according to claim 4, wherein, The plurality of cathode voxel layers have a total thickness of 30 microns to 250 microns; Each cathode voxel layer in the plurality of cathode voxel layers independently has a thickness of 10 microns to 120 microns; or A combination thereof.

6. The electrochemical cell unit according to claim 4, wherein, The plurality of cathode voxel layers include: A first plurality of cathode voxel layers disposed on the cathode current collector; and A second plurality of cathode voxel layers disposed on the first plurality of cathode voxel layers, Wherein, each cathode voxel layer in the first plurality of cathode voxel layers independently has a thickness of 10 microns to 20 microns, and Wherein, each cathode voxel layer in the second plurality of cathode voxel layers independently has a thickness of 20 microns to 30 microns.

7. A method for fabricating a cathode of an electrochemical cell unit for an electric vehicle, wherein the electrochemical cell unit includes a cathode, an anode, and an electrolyte located between the cathode and the anode, the method comprising: Providing a donor foil; Providing a carrier substrate disposed adjacent to the donor foil; Providing an optical system; Providing a current collector defined by an X-Y plane; Activating the optical system to generate a laser beam passing through the donor foil and the carrier substrate, thereby generating a first plurality of cathode voxels; Collecting the first plurality of cathode voxels on the current collector to form one or more first cathode voxel layers; Activating the optical system to generate a laser beam passing through the donor foil and the carrier substrate, thereby generating a second plurality of cathode voxels; And Collecting the second plurality of cathode voxels on the one or more first cathode voxel layers to form one or more second cathode voxel layers, Wherein, the total thickness of one or more first cathode voxel layers and one or more second cathode voxel layers is from 20 microns to 500 microns.

8. The method according to claim 7, wherein the total thickness of the one or more first cathode voxel layers and the one or more second cathode voxel layers is from 30 microns to 250 microns; each of the one or more first cathode voxel layers independently has a thickness of 10 μm to 120 μm; or a combination thereof.

9. The method according to claim 7, wherein, The first plurality of cathode voxels includes a first group of cathode voxels and a second group of cathode voxels, and the second plurality of cathode voxels includes a third group of cathode voxels and a fourth group of cathode voxels, wherein the first group of cathode voxels is spaced apart from the second group of cathode voxels along the X-Y plane, or the first group of cathode voxels at least partially overlaps with the second group of cathode voxels along the X-Y plane, and wherein the third group of cathode voxels is spaced apart from the fourth group of cathode voxels along the X-Y plane, or the third group of cathode voxels at least partially overlaps with the fourth group of cathode voxels along the X-Y plane.

10. The method according to claim 9, wherein The first group of cathode voxels has a first thickness in the Z direction perpendicular to the X-Y plane, the second group of cathode voxels has a second thickness in the Z direction perpendicular to the X-Y plane, the third group of cathode voxels has a third thickness in the Z direction perpendicular to the X-Y plane, the fourth group of cathode voxels has a fourth thickness in the Z direction perpendicular to the X-Y plane, the first thickness is greater than the second thickness, and the third thickness is greater than the fourth thickness.

Images