METHOD AND DEVICE FOR MANUFACTURING ALKALINE METAL-COATED POWER COLLECTORS FOR BATTERIES

Abstract

A method for producing an alkali metal coated current collector for a battery, wherein the method comprises melting the alkali metal, removing impurities floating on the surface of the molten alkali metal, and applying the purified molten alkali metal to the surface of at least one side of a passing current collector substrate to form a coating on the current collector substrate.A system for manufacturing an alkali metal-coated current collector for a battery comprises at least one extruder, a melting chamber, an inlet extending into the melting chamber, at least one feed roller in the inlet for feeding alkali metal introduced into the inlet into the melting chamber; a heater for melting alkali metal in the melting chamber; an opening in the chamber for removing impurities floating on the molten alkali metal in the melting chamber; an outlet extending from the melting chamber to a discharge opening; a reservoir for receiving molten alkali metal; and at least one drive roller for driving a current collector substrate past the reservoir to receive a coating of molten alkali metal.

Description

INTRODUCTION

[0001] The information provided in this section is intended to provide a general context for the disclosure. Work by the presently named inventors, to the extent described in this section, as well as aspects of the description that might not otherwise be prior art at the time of filing, are neither expressly nor impliedly admitted as prior art to the present disclosure.

[0002] The present disclosure relates to methods and apparatus for making alkali metal coated current collectors such as those used in batteries.

[0003] Current processes and apparatus for manufacturing alkali metal coated current collectors have a number of disadvantages, including complexity and space requirements for carrying out such processes and using such apparatus. SUMMARY

[0004] Embodiments of the methods and apparatus of this disclosure provide streamlined processes and simplified and more compact apparatus for manufacturing alkali metal coated current collectors such as those used in batteries.

[0005] According to a first embodiment of this disclosure, a method for fabricating an alkali metal-coated current collector is provided. In this first embodiment, the alkali metal is first melted in an inert atmosphere, and impurities floating on the surface of the molten metal are removed. The purified metal is then applied directly to the surface of at least one side of a current collector substrate, and optionally to both sides of the current collector substrate. These current collector substrates are typically a thin foil or mesh made of stainless steel, copper, aluminum, titanium, carbon fiber, or another suitable material. In some embodiments, the alkali metal is applied as the current collector substrate moves vertically.

[0006] According to a second embodiment of this disclosure, an apparatus for manufacturing an alkali metal-coated current collector is provided. This apparatus may comprise one or more extruders, each having a melting chamber, an inlet extending to the melting chamber, at least one feed roller in the inlet for feeding the alkali metal introduced into the inlet to the melting chamber, and a heater for melting the alkali metal in the melting chamber. The feed rollers may be adjustable, such as by spring tension, magnetism, electromagnetism, or air pressure, to provide an appropriate contact force for the alkali metal added to the melting chamber. There may be an orifice in each melting chamber for removing impurities floating on the molten alkali metal in the melting chamber.There is also an outlet extending from the melting chamber to discharge the molten alkali metal to a discharge port and then to a discharge chamber.

[0007] At least one drive roller drives a current collector substrate vertically through the dispensing chamber, where alkali metal is applied to both surfaces of the current collector substrate. The apparatus may include a temperature-controlled zone for conditioning the coated substrate. Following the temperature-controlled zone, optional, post-extrusion-controlled, tipped scrapers may further condition the surface of the alkali metal on the current collector substrate. A pair of conditioning rollers may further treat the surface and assist in driving the substrate through the dispensing chamber.

[0008] According to a third embodiment of this disclosure, an apparatus for manufacturing an alkali metal-coated current collector is provided. This apparatus may comprise one or more extruders, each having a melting chamber in the form of a passageway, an inlet extending to the melting chamber, at least one feed roller in the inlet for feeding the alkali metal introduced into the inlet to the melting chamber, and a heater for melting the alkali metal in the melting chamber. There is also an outlet extending from the melting chamber for discharging the molten alkali metal through an outlet opening to a manifold containing a discharge chamber.

[0009] At least one drive roller drives a current collector substrate vertically through the dispensing chamber, where alkali metal is applied to both surfaces of the current collector substrate. The apparatus may include a temperature-controlled zone for conditioning the coated substrate. Following the temperature-controlled zone, optional, post-extrusion-controlled, tipped scrapers may further condition the surface of the alkali metal on the current collector substrate. A pair of conditioning rollers may further treat the surface and assist in driving the substrate through the dispensing chamber.

[0010] According to a fourth embodiment of this disclosure, an apparatus for manufacturing an alkali metal-coated current collector is provided. This apparatus may comprise one or more extruders, each having a melting chamber in the form of a passageway, an inlet extending to the melting chamber, at least one feed roller in the inlet for feeding the alkali metal introduced into the inlet to the melting chamber, and a heater for melting the alkali metal in the melting chamber. There is also an outlet extending from the melting chamber for discharging molten alkali metal through an outlet opening into a storage container and subsequently into a discharge chamber connected to the storage container. The recirculation lines recirculate the molten metal from the discharge chamber back to the storage container.

[0011] At least one drive roller drives a current collector substrate vertically through the reservoir and the dispensing chamber, applying alkali metal to both surfaces of the current collector substrate. The apparatus may include a temperature-controlled zone for conditioning the coated substrate. Following the temperature-controlled zone, optional, post-extrusion-controlled, tipped scrapers may further condition the surface of the alkali metal on the current collector substrate. A pair of conditioning rollers may further treat the surface and assist in driving the substrate through the dispensing chamber.

[0012] According to a fifth embodiment of this disclosure, an apparatus for manufacturing an alkali metal-coated current collector is provided. This apparatus may comprise an extruder, each of which has a melting chamber in the form of a passage, an inlet extending to the melting chamber, at least one feed roller in the inlet for feeding the alkali metal introduced into the inlet to the melting chamber, and a heater for melting the alkali metal in the melting chamber. An outlet extending from the melting chamber is also provided for discharging molten alkali metal through an outlet opening to a discharge chamber formed between two rollers.

[0013] At least one drive roller propels a current collector substrate past the dispensing chamber, where alkali metal is applied to the surface of the current collector substrate. The opposite side of the current collector substrate may be supported on a table, which may optionally be ultrasonically driven to distribute the metal applied to the current collector substrate. The apparatus may include a temperature-controlled zone for conditioning the coated substrate. Optional post-extrusion controlled strippers may be employed after the temperature-controlled zone to further condition the surface of the alkali metal. A pair of conditioning rollers may further treat the surface and help propel the substrate past the dispensing chamber.

[0014] According to a sixth embodiment of this disclosure, an apparatus for manufacturing an alkali metal-coated current collector is provided. This apparatus may comprise one or more extruders, each having a melting chamber in the form of a passageway, an inlet extending to the melting chamber, at least one feed roller in the inlet for feeding the alkali metal introduced into the inlet to the melting chamber, and a heater for melting the alkali metal in the melting chamber. There is also an outlet extending from the melting chamber for discharging molten alkali metal through a discharge opening to a reservoir. The reservoir has a bypass through which impurities floating on the surface of the molten alkali metal can be separated from the molten alkali metal. The reservoir empties via an outlet into a discharge chamber formed between feed rollers.At least one drive roller drives a current collector substrate past the dispensing chamber, depositing alkali metal onto a surface of the current collector substrate. The apparatus may include a temperature-controlled zone for conditioning the coated substrate. Following the temperature-controlled zone, optional, post-extrusion-controlled, tipped scrapers may further condition the surface of the alkali metal. A pair of conditioning rollers may further treat the surface and help drive the substrate past the dispensing chamber.

[0015] Further areas of applicability of the present disclosure will become apparent from the detailed description, claims, and drawings. The detailed description and specific examples are for illustrative purposes only and are not intended to limit the scope of the disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The present disclosure will be more fully understood from the detailed description and the accompanying drawings, in which: Fig. 1 is a flow diagram of a method for manufacturing an alkali metal coated current collector according to a first embodiment of this disclosure; Fig. 2 is a schematic diagram of an apparatus for manufacturing an alkali metal coated current collector according to a second embodiment of this disclosure; Fig. 3 is a schematic diagram of an apparatus for manufacturing an alkali metal coated current collector according to a third embodiment of this disclosure; Fig. 4 is a schematic diagram of an apparatus for manufacturing an alkali metal coated current collector according to a fourth embodiment of this disclosure; Fig. 5 is a schematic diagram of an apparatus for manufacturing an alkali metal coated current collector according to a fifth embodiment of this disclosure; and Fig. 6 is a schematic diagram of an apparatus for manufacturing an alkali metal coated current collector according to a sixth embodiment of this disclosure;

[0017] Reference symbols may be reused in the drawings to identify similar and / or identical elements. DETAILED DESCRIPTION

[0018] A method of manufacturing an alkali metal coated current collector according to a first embodiment of this disclosure is described in Fig. 1 is generally indicated as 20. This alkali metal can be one of the alkali metals (lithium, sodium, potassium, rubidium, and cesium), in particular lithium, which is frequently used in batteries. According to this first embodiment, at 22 the alkali metal is first melted in an inert atmosphere, and at 24 impurities floating on the surface of the molten alkali metal are removed. At 26, the purified metal is then applied directly to the surface of at least one side of a current collector substrate, and optionally to both sides of the current collector substrate. The alkali metal can be between 1 µm and about 100 µm thick. In some embodiments, the alkali metal is applied as the current collector substrate moves vertically and is applied to both sides of the collector substrate.

[0019] An apparatus for manufacturing an alkali metal coated current collector according to a second embodiment of this disclosure is described in Fig. 2, generally designated 100. This apparatus 100 may include one or more extruders 102, each having a melting chamber 104 in the form of a cavity inside the extruder and an inlet 106 extending into the melting chamber. At least one feed roll 108 may be located in the inlet 106 to feed the alkali metal introduced into the inlet into the melting chamber. The inlet 106 and the feed rolls 108 may feed alkali metal in the form of plates, coupons, or rolled stock. The extruders 102 may include a heater, such as an induction heater, for melting alkali metal in the melting chamber 104.

[0020] The operating speed of the rollers 108 and the operation of the heater can be coordinated to dispense the alkali metal at the correct temperature and in the correct amount to coat the current collector substrate. Furthermore, the heater can include thermostatic control. Furthermore, the feed rollers can be adjustable, such as by spring tension, magnetism, electromagnetism, or air pressure, to provide an appropriate contact force for the alkali metal being added to the melting chamber and to ensure that the material feed is not obstructed or otherwise restricted.

[0021] An opening 110 may be provided in the melting chamber 104 for removing impurities floating on the molten alkali metal in the melting chamber. The impurities, such as metal oxides and foreign matter, may be collected in containers 112. An outlet 114 extending from the melting chamber 104 is also provided for discharging the molten alkali metal to a discharge opening 116 in a discharge chamber 118. The discharge chamber 118 may also include a heater, such as an induction heater, which is optionally thermostatically controlled to maintain the temperature of the molten alkali metal within a suitable temperature range for deposition on the current collector substrate.

[0022] At least one drive roller 120 drives a current collector substrate 122 vertically through the dispensing chamber 118, where alkali metal layers 124, 126 are applied to both surfaces of the current collector substrate. The apparatus 120 may include a temperature-controlled zone 128 for conditioning the coated substrate. After the temperature-controlled zone 128, optional, post-extrusion-controlled strippers 130 with tips 132 may further condition the surface of the alkali metal on the current collector substrate. A pair of conditioning rollers 134 may further treat the surface and assist in driving the substrate through the dispensing chamber.

[0023] An apparatus for manufacturing an alkali metal coated current collector according to a third embodiment of this disclosure is described in Fig. 3, generally designated 200. The apparatus 200 is similar to the apparatus 100, and corresponding parts are designated by corresponding reference numerals. The apparatus 200 may include one or more extruders 102', each having a melting chamber 104' in the form of a passageway within the extruder. There may be an inlet 106 extending to the melting chamber 104'. There may be at least one feed roll 108 in the inlet 106 to feed the alkali metal introduced into the inlet into the melting chamber. The inlet 106 and the feed rolls 108 may feed alkali metal in the form of slabs, coupons, or rolled stock. The extruders 102' may include a heater, such as an induction heater, for melting alkali metal in the melting chamber 104'.

[0024] The operating speed of the rollers 108 and the operation of the heater can be coordinated to deliver the alkali metal at the correct temperature and in the correct amount to coat the current collector substrate. Furthermore, the heater can include a thermostatic control.

[0025] An outlet 114 extends from the melting chamber 104' to discharge molten alkali metal to a discharge opening 116 in a discharge chamber 118. The discharge chamber 118 may also include a heater, such as an induction heater, which is optionally thermostatically controlled to maintain the temperature of the molten alkali metal within a suitable temperature range for deposition on the current collector substrate. Temperature sensors may be provided at the discharge opening 116 and in the discharge chamber 118.

[0026] An opening 236 may be provided in the dispensing chamber 118 to remove excess lithium into a collection chamber 238 and to maintain the liquid pouring pressure in the dispensing chamber.

[0027] At least one drive roller 120 drives a current collector substrate 122 vertically through the dispensing chamber 118, where alkali metal layers 124, 126 are applied to both surfaces of the current collector substrate. The apparatus 120 may include a temperature-controlled zone 128 for conditioning the coated substrate. After the temperature-controlled zone 128, optional, post-extrusion-controlled strippers 130 with tips 132 may further condition the surface of the alkali metal on the current collector substrate. A pair of conditioning rollers 134 may further treat the surface and assist in driving the substrate through the dispensing chamber.

[0028] An apparatus for manufacturing an alkali metal coated current collector according to a fourth embodiment of this disclosure is described in Fig. 4, generally indicated at 300. The apparatus 300 is similar to the apparatus 200, and corresponding parts are designated by corresponding reference numerals. The apparatus 300 may include one or more extruders 102', each having a melting chamber 104' in the form of a passageway within the extruder. There may be an inlet 106 extending into the melting chamber 104'. There may be at least one feed roll 108 in the inlet 106 to feed the alkali metal introduced into the inlet into the melting chamber. The inlet 106 and the feed rolls 108 may feed alkali metal in the form of slabs, coupons, or rolled stock. The extruders 102' may include a heater, such as an induction heater, for melting alkali metal in the melting chamber 104'.

[0029] The operating speed of the rollers 108 and the operation of the heater can be coordinated to deliver the alkali metal at the correct temperature and in the correct amount to coat the current collector substrate. Furthermore, the heater can include a thermostatic control.

[0030] An outlet 114 extends from the melting chamber 104' to discharge molten alkali metal to a discharge opening 116 in a discharge chamber 118. The discharge chamber 118 may also include a heater, such as an induction heater, which is optionally thermostatically controlled to maintain the temperature of the molten alkali metal within a suitable temperature range for deposition on the current collector substrate. Temperature sensors may be provided at the discharge opening 116 and in the discharge chamber 118.

[0031] Openings 240, 242 and passages 244 may be provided at the bottom of the discharge chamber 118 to return the molten alkali metal to the discharge chamber 118. A conduit 246 opening may be provided in the discharge chamber 118 for removing impurities floating on the molten alkali metal in the discharge chamber. The impurities, such as metal oxides and foreign matter, may be collected in a series of containers 248, 250, with the impurities concentrating in the second container 248.

[0032] At least one drive roller 120 drives a current collector substrate 122 vertically through the dispensing chamber 118, where alkali metal layers 124, 126 are applied to both surfaces of the current collector substrate. The apparatus 300 may include a temperature-controlled zone 128 for conditioning the coated substrate. After the temperature-controlled zone 128, optional post-extrusion controlled strippers 130 with tips 132 may further condition the surface of the alkali metal on the current collector substrate. A pair of conditioning rollers 134 may further treat the surface and assist in driving the substrate through the dispensing chamber.

[0033] An apparatus for manufacturing an alkali metal coated current collector according to a fifth embodiment of this disclosure is described in Fig.5, generally indicated at 400. This apparatus 400 may include an extruder 402 having a melting chamber 404 in the form of a passageway. There may be an inlet 406 extending into the melting chamber 404. There may be at least one feed roll 408 in the inlet 106 to feed the alkali metal introduced into the inlet 406 into the melting chamber 404. The inlet 406 and the feed rolls 408 may feed alkali metal in the form of slabs, coupons, or rolled stock. The extruder 402 may include a heater, such as an induction heater, for melting alkali metal in the melting chamber 404.

[0034] The operating speed of the rollers 408 and the operation of the heater can be coordinated to deliver the alkali metal at the correct temperature and in the correct amount to coat the current collector substrate. Furthermore, the heater can include a thermostatic control.

[0035] An outlet 414 is provided extending from the melting chamber 404 to discharge molten alkali metal to a discharge opening 416 into a discharge chamber 418 formed between two rollers 420 adjacent to the discharge opening 416. Temperature sensors may be provided at the discharge opening 116 and / or in the rollers 420.

[0036] At least one drive roller 422 drives a current collector substrate 424 past the dispensing chamber 418, where a layer of alkali metal 426 is applied to the surface of the current collector substrate 424. The opposite side of the current collector substrate may be supported on a table 428, which may optionally be ultrasonically driven to distribute the metal applied to the current collector substrate 424. The apparatus may include a temperature-controlled zone 430 for conditioning the coated substrate. Following the temperature-controlled zone, optional post-extrusion controlled strippers (not shown) may further condition the surface of the alkali metal. A pair of conditioning rollers 432 may further treat the surface and assist in driving the substrate 434 past the dispensing chamber 418.

[0037] An apparatus for manufacturing an alkali metal-coated current collector according to a sixth embodiment of this disclosure is generally indicated at 500. This apparatus may include one or more extruders 502, each having a melt chamber 504 in the form of a passageway and an inlet 506 extending into the melt chamber. At least one feed roll 508 may be present in the inlet 506 to feed the alkali metal introduced into the inlet 506 into the melt chamber 504. The inlet 506 and the feed rolls 508 may feed alkali metal in the form of plates, coupons, or rolled stock. The feed rolls may be adjustable, such as by spring tension, magnetism, electromagnetism, or air pressure, to provide an appropriate contact force for the lithium and ensure that the material feed is not obstructed or otherwise restricted.The extruder 502 may include a heater, such as an induction heater, for melting alkali metal in the melting chamber 504.

[0038] The operating speed of the rollers 508 and the operation of the heater can be coordinated to deliver the alkali metal at the correct temperature and in the correct amount to coat the current collector substrate. Furthermore, the heater can include a thermostatic control.

[0039] An outlet 514 extends from the melting chamber 504 to discharge molten alkali metal through a discharge opening 516 to a pressurized crucible 518. The crucible allows the escape of gas trapped in the alkali metal to reduce the porosity of the discharged lithium and improve the surface quality of the lithium deposited on the substrate. In other cases, it may be desirable to sparge gas through the molten alkali metal to reduce its density and impart porosity to the metal deposited on the substrate. The crucible 518 has a gas inlet 520 and a gas outlet 522 for circulating an inert gas (e.g., argon) to provide an inert, pressurized environment within the crucible.

[0040] The crucible 518 includes a bypass 524 through which impurities floating on the surface of the molten alkali metal can be separated from the molten alkali metal. A wheel 525 can push floating impurities into the bypass 524. An opening 526 allows the impurities to flow to one or more containers (not shown), such as the containers 248, 250 described above. The crucible 518 discharges via an outlet 528 into a discharge chamber 530 formed between the discharge rollers 532, 534. A piston 540 can be provided to force molten alkali metal from the crucible through the outlet 528. A table, such as table 428, can be provided to support the substrate 538 while the alkali metal coating is applied.

[0041] At least one drive roller 536 drives a current collector substrate 538 past the dispensing chamber 530, where a layer of alkali metal 542 is applied to a surface of the current collector substrate. The apparatus may include a temperature-controlled zone for conditioning the coated substrate. After the temperature-controlled zone, optional, post-extrusion-controlled, tipped scrapers may further condition the surface of the alkali metal. A pair of conditioning rollers may further treat the surface and help propel the substrate past the dispensing chamber. All are as shown and described above with respect to the apparatus 400.

[0042] The foregoing description is merely illustrative and is not intended to limit the disclosure, its application, or uses in any way. The broad teachings of the disclosure may be embodied in a variety of forms. Therefore, while this disclosure includes specific examples, the true scope of the disclosure should not be limited thereto, since other changes will become apparent after studying the drawings, the patent specification, and the following claims. It is understood that one or more steps within a method may be performed in a different order (or simultaneously) without altering the principles of the present disclosure.Furthermore, although the embodiments are each described above as having specific features, any one or more of these features described with respect to one embodiment of the disclosure may be implemented and / or combined with features of any of the other embodiments, even if this combination is not expressly described. In other words, the described embodiments are not mutually exclusive, and an exchange of one or more embodiments for one another remains within the scope of this disclosure.

[0043] Spatial and functional relationships between elements (e.g., between modules, circuit elements, semiconductor layers, etc.) are described using various terms, including "connected," "engaging," "coupled," "adjacent," "beside," "on top of," "over," "below," and "disposed." Where a relationship between first and second elements is not explicitly described as "direct" in the above disclosure, that relationship may be a direct relationship, with no other intervening elements between the first and second elements, or an indirect relationship, with one or more intervening elements (either spatial or functional) between the first and second elements.As used herein, the term “A, B and / or C” should be construed as logical (A ORed with B ORed with C) using a non-exclusive logical OR and should not be understood as “at least one of A, at least one of B and at least one of C”.

[0044] In the figures, the direction of an arrow, as indicated by the arrowhead, generally illustrates the flow of information (such as data or instructions) of interest to the illustration. For example, if element A and element B exchange a plurality of pieces of information, but the information sent from element A to element B is relevant to the illustration, the arrow may point from element A to element B. This unidirectional arrow does not imply that no other information is sent from element B to element A. Further, for information sent from element A to element B, element B may send requests or acknowledgments for the information to element A.

Claims

[1] A method of manufacturing an alkali metal coated current collector for a battery, the method comprising: Melting the alkali metal in an inert atmosphere; Removing impurities floating on the surface of the molten alkali metal; and Applying the purified molten alkali metal to the surface of at least one side of a passing current collector substrate to form a coating of about 1 µm to about 100 µm thick on the current collector substrate. [2] A method of manufacturing an alkali metal coated current collector according to claim 1, wherein the step of applying the purified alkali metal to the passing current collector substrate comprises applying the purified alkali metal to both sides of the passing current collector substrate. [3] A method of manufacturing an alkali metal coated current collector according to claim 2, wherein the current collector substrate is moved vertically downward through a discharge chamber containing the purified molten alkali metal. [4] A method of manufacturing an alkali metal coated current collector according to claim 1, wherein the current collector substrate is moved horizontally past a discharge chamber containing the purified molten alkali metal. [5] A method of manufacturing an alkali metal coated current collector according to claim 1, further comprising passing the alkali metal coated current collector substrate past a conditioning stripper to condition the surface of the alkali metal coating. [6] A method for producing an alkali metal coated current collector according to claim 1, wherein the alkali metal is melted in an extruder having a feed opening with at least one feed wheel for drawing alkali metal into the extruder for melting. [7] A method of manufacturing an alkali metal coated current collector according to claim 6, wherein the extruder has a nozzle extending substantially across the width of the current collector substrate. [8] A method of manufacturing an alkali metal coated current collector according to claim 1, wherein the extruder die has an edge for conditioning the surface of the alkali metal coating. [9] A method of manufacturing an alkali metal coated current collector according to claim 1, wherein floating impurities are removed by passing the gas over the surface of the molten alkali metal to force the floating impurities out of an outlet. [10] A system for producing an alkali metal coated current collector for a battery, the system comprising: at least one extruder having a melting chamber, an inlet extending into the melting chamber, at least one feed roller in the inlet for feeding alkali metal introduced into the inlet into the melting chamber; a heater for melting alkali metal in the melting chamber; an opening in the chamber for removing impurities floating on the molten alkali metal in the melting chamber; an outlet extending from the melting chamber to a discharge opening; a reservoir for receiving molten alkali metal; and at least one drive roller driving a current collector substrate past the reservoir to receive a coating of molten alkali metal.

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