METHOD FOR PRODUCING AN ELECTRODE USING AN AUTOMATED FOLDING CALENDAR

Abstract

A method for manufacturing an electrode comprises feeding an electrode mixture onto a first conveyor belt. The electrode mixture comprises electrode active materials, conductive carbons, and polymeric binders. The first conveyor belt moves the electrode mixture film along a first belt movement direction. The method further comprises transferring the electrode mixture film from the first conveyor belt to a second conveyor belt. The second conveyor belt moves the electrode mixture film along a second longitudinal direction. The first belt movement direction is angled obliquely relative to the second longitudinal direction. The side rollers of the second conveyor belt fold the electrode mixture film at a predetermined angle with the assistance of a pair of guide rollers. The method comprises hot-pressing the electrode mixture film using at least one hot roller to fiberize the PTFE binder along the second belt movement direction.

Description

INTRODUCTION

[0001] The present disclosure relates generally to electrode manufacturing and, more particularly, to electrode manufacturing using an automated folding calender.

[0002] This introduction generally presents the context of the disclosure. Work by the present inventors, to the extent described in this introduction, as well as aspects of the description that may not otherwise be considered prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against this disclosure.

[0003] An N-methylpyrrolidone (NMP)-free manufacturing process for electrode fabrication, using a process-friendly alcohol as a processing solvent, requires a series of repeated hot-pressing and folding steps to fiberize the polytetrafluoroethylene (PTFE) binders in the electrode active material. However, this process operates in a batch-to-batch design, posing challenges for efficiency and scalability. Therefore, it is desirable to maximize the efficiency of this manufacturing process.

[0004] For the state of the art, reference is made to CN 1 11 716 616 A, DE 689 05 034 T2 and WO 2014 / 175 756 A1. SUMMARY

[0005] A method for manufacturing an electrode comprises feeding an electrode mixture onto a first conveyor belt. The electrode mixture comprises an electrode active material, conductive carbons, and a polymeric binder.

[0006] The first conveyor belt moves the electrode mixture along a first belt movement direction. The method also includes transferring the electrode mixture from the first conveyor belt to a second conveyor belt. The second conveyor belt moves the electrode mixture along a second longitudinal direction. The first belt movement direction is obliquely angled relative to the second longitudinal direction. A pair of side rollers on the second conveyor belt folds the electrode mixture at a predetermined oblique angle as the electrode mixture film is transferred from the first conveyor belt to the second conveyor belt with the assistance of a pair of guide rollers. The distance between the pair of side rollers on the second conveyor belt, a diameter of each of the pair of guide rollers, and a position of the pair of guide rollers control a width of the folded electrode mixture film.The method also includes hot pressing the electrode mixture using at least one hot roll to fiberize the polytetrafluoroethylene (PTFE) binder along the second belt travel direction after the electrode mixture is transferred from the first conveyor belt to the second conveyor belt.

[0007] In some aspects of the present disclosure, the electrode mixture is free of N-methylpyrrolidone (NMP). The polymeric binder is a polytetrafluoroethylene (PTFE) binder. The method may comprise feeding the electrode mixture into a hopper before feeding the electrode mixture to the first conveyor. The method may comprise calendering the electrode mixture after feeding the electrode mixture into the hopper and before feeding the electrode mixture to the first conveyor. Hot rolls may be used to calender the electrode mixture. The method may comprise trimming the electrode mixture and energizing the hopper using scrapers. The scrapers are connected to the hot roll (located before the first conveyor).

[0008] The present disclosure also describes a manufacturing assembly for producing an electrode. The manufacturing assembly includes a first conveyor belt configured to move an electrode mixture along a first belt travel direction. The electrode mixture includes electrode active materials, conductive carbons, and polymeric binders. The assembly also includes a second conveyor belt positioned to directly receive the electrode mixture from the first conveyor belt. The second conveyor belt is configured to move the electrode mixture along a second longitudinal direction. The first belt travel direction is angled obliquely relative to the second longitudinal direction to fold the electrode mixture as the electrode mixture is transferred from the first conveyor belt to the second conveyor belt.The assembly also includes one or more hot rollers positioned for hot pressing the electrode mixture and moving with the second conveyor belt along the second belt movement direction.

[0009] Further areas of applicability of the present disclosure will become apparent from the detailed description below. It should be understood that the detailed description and specific examples are for purposes of illustration only and are not intended to limit the scope of the disclosure.

[0010] The above features and advantages, as well as other features and advantages of the presently disclosed system and method, are readily apparent from the detailed description, including the claims and exemplary embodiments, taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The present disclosure will become more fully understood from the detailed description and the accompanying drawings, in which: Fig. 1 is a schematic plan view of a production arrangement with an automated folding calender. Fig. 2 a schematic side view of a feed of the production arrangement with automated folding calender of Fig. 1 is. Fig. 3 is a schematic plan view of an automated folding and calendering unit of the production arrangement with automated folding calender of Fig. 1. Fig. 4 a schematic side view of the guide rollers of the automated folding and calendering unit of Fig. 3 is. Fig. 5 is a schematic plan view of a manufacturing arrangement comprising a feeder and a plurality of automated folding and calendering units arranged in series of Fig. 3. Fig. 6 is a schematic plan view of a manufacturing arrangement comprising a feeder and a plurality of vertically stacked automated folding and calendering units of Fig. 3. Fig. 7 is a flow chart of a method for manufacturing an electrode using the automated folding calender manufacturing arrangement of Fig. 1. DETAILED DESCRIPTION

[0012] Reference will now be made in detail to several examples of the disclosure, which are illustrated in the accompanying drawings. Wherever possible, like or similar reference characters are used throughout the drawings and the description to refer to like or similar parts or steps.

[0013] Fig. 1-3 show a manufacturing system with an automated folding calender 100 for producing electrodes for batteries. The manufacturing system 100 is capable of multidirectionally calendering electrode films from roll to roll, thereby improving the manufacturing efficiency of electrodes. In the illustrated embodiment, the manufacturing system 100 comprises a feeder 102 and an automated folding and calendering unit 104. The electrode mixture 106 is introduced into the feeder 102. The feeder 102 is located upstream of the automated folding and calendering unit 104 and is configured to feed the electrode mixture 106 to the automated folding and calendering unit 104. The electrode mixture 106 comprises electrode active materials, conductive carbons, and polymeric binders. The electrode mixture may be free of N-methylpyrrolidone (NMP) to minimize environmental impact.The polymeric binder may, for example, include a polytetrafluoroethylene (PTFE) binder to increase the strength of the electrode mixture. In the present disclosure, the term "electrode active materials" refers to cathode materials, anode materials, and / or electrochemically active materials, including solvents, additives, solid-state electrolytes, and electrolyte salts, that contribute to the electrochemical processes required for energy storage.

[0014] With reference to Fig. 2, the feeder 102 includes a hopper 108, one or more hot rollers 110 downstream of the hopper 108, and one or more strippers 112. The hopper 108 is configured to receive the electrode mixture 106 and feed it to the hot rollers 110. The hot rollers 110 are configured to press the electrode mixture 106 and are maintained at a temperature between room temperature (i.e., twenty degrees Celsius) and two hundred degrees Celsius to facilitate calendering of the electrode mixture 106. The hot rollers 110 are used to calender the electrode mixture 106 and convert it into an electrode mixture film 106. The speed offset of the hot rollers 110 can be adjusted between 0% and 100%. After this hot pressing by the hot rollers 110, the electrode mixture 106 can be labeled as an electrode film.The strippers 112 are located downstream of the hot rolls 110 to trim the electrode mixture that excites the hopper 108. The strippers 112 can be used to strip the electrode film from the hot rolls 110 and clean the remaining material.

[0015] With reference to Fig. 1 and Fig. 3, the automated folding and calendering unit 104 is positioned to receive the electrode mixture 106 exiting the feeder 102. In other words, the automated folding and calendering unit 104 is located downstream of the feeder 102. The automated folding and calendering unit 104 includes a first conveyor belt 114 and one or more edge trimmers 116 coupled to the first conveyor belt 114. The first conveyor belt 114 is configured to move the electrode mixture 106 along a first belt travel direction 118. The edge trimmers 116 are configured to trim the edges of the electrode mixture 106 moved by the first conveyor belt 114.

[0016] With reference to Fig. 1, Fig. 3 and Fig. 4, the automated folding and calendering unit 104 includes a second conveyor belt 120 positioned downstream of the first conveyor belt 114. Accordingly, the second conveyor belt 120 is positioned to receive the electrode mixture film 106 exiting the first conveyor belt 114. The second conveyor belt 120 is configured to move the electrode mixture film 106 along a second belt travel direction 122. The second belt travel direction 122 is angled obliquely relative to the first belt travel direction 118. The pair of side rollers 126 on the second conveyor belt 122 fold the electrode mixture film 106 at a predetermined oblique angle as the electrode mixture film is transferred from the first conveyor belt 114 to the second conveyor belt 122 with the assistance of the pair of guide rollers 124.The distance between the pair of side rollers 126 on the second conveyor belt 120, the diameter and the position of each of these pairs control the width of the folded electrode mixture film 106. . Fig. 1 shows the folding direction 113. The automated folding and calendering unit 104 includes one or more guide rollers 124 along the second conveyor belt 120 to facilitate folding the electrode mixture 106. The automated folding and calendering unit 104 further includes one or more side rollers 126 positioned along the edges of the second conveyor belt 120 to facilitate folding the electrode mixture 106. One or more strippers 112 may be coupled to the side rollers 126 to trim off excess electrode mixture 106 moved by the second conveyor belt 120. The automated folding and calendering unit 104 further includes one or more heat rollers 110 disposed downstream of the side rollers 126 and the guide rollers 124.These hot rollers 110 are positioned to hot-press the electrode mixture film 106 moved by the second conveyor belt 120, thereby shredding the PTFE binders along the second belt travel direction 122. The hot rollers 110 are used to calender the electrode mixture 106. One or more strippers 112 may be positioned downstream of these hot rollers 110 to trim off the excess electrode mixture film 106. The hot rollers 110 are designed to press the electrode mixture film 106 and are maintained at a temperature between room temperature (i.e., twenty degrees Celsius) and two hundred degrees Celsius to facilitate calendering the electrode mixture 106. In . Fig. 2, the dashed lines 128 represent the edges of the electrode mixture film (i.e., the electrode mixture 106 after hot pressing by the hot rollers 110 coupled to the hopper 108).

[0017] With reference to Fig. 5, the manufacturing assembly 10 may comprise a feeder 102 and a plurality of serially arranged (i.e., in-line) automatic folding and calendering units 104.

[0018] With reference to Fig. 6, the manufacturing assembly 100 may include a feeder 102 and a plurality of vertically stacked automated folding and calendering units 104, thereby reducing the footprint of the equipment.

[0019] Fig.7 is a method 200 for manufacturing an electrode of a battery. The method 200 begins at block 202. The manufacturing method 200 may be applied to solvent-free mixed dough (i.e., electrode mixture 106), with the option of applying traces of solvent to the film prior to hot calendering to improve the cohesion and formability of the folded film. The solvent may be alcohol, ester, glycol, or mixtures thereof. At block 202, the electrode mixture 106 is introduced into the hopper 108. Then, the method 200 continues at block 204. At block 204, the electrode mixture 106 is calendered into a thick film by the hot rollers 110. Excess material may be trimmed off by the scrapers 112. Then, the method 200 continues at block 206.At block 206, the thick electrode mixture film is folded at a predetermined oblique angle by the side rollers 126 with the assistance of the guide rollers 124 as the electrode mixture film 106 is transferred from the first conveyor belt 114 to the second conveyor belt 120. Specifically, the electrode mixture film 106 is rolled up by the side rollers 126 and the guide rollers 124. The guide rollers 124 are adjustable and are used to support the upper surface of the electrode film. Furthermore, the distance between the two side rollers 126 on the second conveyor belt 120 and the diameter and position of each of these pairs control the width of the folded electrode mixture film 106. The method 200 then proceeds to block 208. At block 208, the electrode mixture film 106 is hot calendered by the hot rollers 110 located on the second conveyor belt 120 to form a new electrode film.The hot rolls 110 also help to fibrillate the polymeric binders (e.g., PTFE binders) along the second belt travel direction 122 and a transverse direction transverse to the second belt travel direction 122. Blocks 204, 206, and 208 are repeated as needed until a dense, strong film with the desired degree of PTFE fibrillation is obtained.

[0020] While exemplary embodiments are described above, it is not intended that these embodiments describe all possible forms encompassed by the claims. The words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the disclosure. As previously described, the features of various embodiments may be combined to form other embodiments of the presently disclosed system and method that may not be explicitly described or illustrated.While various embodiments may have been described as providing advantages or being preferred over other prior art embodiments or designs with respect to one or more desired characteristics, those of ordinary skill in the art will recognize that one or more features or characteristics may be compromised to achieve desired overall system attributes depending on the specific application and design. These attributes may include, but are not limited to, cost, strength, durability, life cycle cost, marketability, appearance, packaging, size, usability, weight, manufacturability, ease of assembly, etc.As such, embodiments that are described as less desirable than other embodiments or prior art embodiments with respect to one or more characteristics are not outside the scope of the disclosure and may be desirable for certain applications.

[0021] The drawings are presented in simplified form and are not to scale. For clarity and convenience, directional terms such as top, bottom, left, right, above, above, below, below, back, and front may be used with reference to the drawings. These and similar directional terms should not be construed to limit the scope of the disclosure in any way.

[0022] Embodiments of the present disclosure are described herein. It should be understood, however, that the disclosed embodiments are merely examples, and other embodiments may take various and alternative forms. The figures are not necessarily to scale; some features may be larger or smaller to show details of particular components. Therefore, the specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the presently disclosed system and method.As will be understood by those of ordinary skill in the art, various features illustrated and described with reference to one of the figures may be combined with features illustrated in one or more of the other figures to produce embodiments not explicitly illustrated or described. The illustrated feature combinations provide representative embodiments for typical applications. However, various combinations and modifications of the features consistent with the teachings of this disclosure may be desired for particular applications or implementations.

[0023] This 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 modifications will become apparent upon examination of the drawings, the patent specification, and the following claims.

Claims

[1] A method for producing an electrode, comprising; Feeding an electrode mixture film to a first conveyor belt, the electrode mixture comprising electrode active materials, conductive carbons, and polymeric binders, and the first conveyor belt moving the electrode mixture along a first belt movement direction; Transferring the electrode mixture film from the first conveyor belt to a second conveyor belt, wherein the second conveyor belt moves the electrode mixture along a second belt movement direction, the first belt movement direction is angled obliquely relative to the second belt movement direction, a pair of side rollers on the second conveyor belt fold the electrode mixture at a predetermined oblique angle as the electrode mixture film is transferred from the first conveyor belt to the second conveyor belt with the assistance of a pair of guide rollers, and a distance between the pair of side rollers on the second conveyor belt, a diameter of each of the two guide rollers, and a position of the pair of guide rollers control the width of the folded electrode mixture film; and after folding the electrode film, hot-pressing the electrode mixture using at least one hot roll to fiberize the polymeric binder along the second belt movement direction. [2] The method of claim 1, wherein the electrode mixture is free of N-methylpyrrolidone (NMP). [3] The method of claim 2, wherein the polymeric binders comprise a polytetrafluoroethylene (PTFE) binder. [4] The method of claim 2, further comprising feeding the electrode mixture into a hopper before feeding the electrode mixture to the first conveyor belt. [5] The method of claim 4, further comprising calendering the electrode mixture into an electrode mixture film after feeding the electrode mixture into the hopper and before feeding the electrode mixture to the first conveyor belt. [6] The method of claim 5, wherein the at least one hot roll is a first hot roll, and wherein at least one second roll is used to calender the electrode mixture. [7] The method of claim 6, further comprising trimming the electrode mixture exiting the funnel. [8] A method for producing an electrode, comprising; Feeding an electrode mixture to a first conveyor belt, wherein the electrode mixture comprises electrode active materials, conductive carbons, and polymeric binders, the first conveyor belt moves the electrode mixture along a first belt movement direction, and the electrode mixture is free of N-methylpyrrolidone (NMP), and the polymeric binders comprise a polytetrafluoroethylene (PTFE) binder; Transferring the electrode mixture film from the first conveyor belt to a second conveyor belt, the second conveyor belt moving the electrode mixture along a second longitudinal direction, the first belt moving direction being obliquely angled relative to the second longitudinal direction, a pair of side rollers on the second conveyor belt folding the electrode mixture at a predetermined oblique angle as the electrode mixture film is transferred from the first conveyor belt to the second conveyor belt with the assistance of a pair of guide rollers, a distance between the pair of side rollers on the second conveyor belt, the diameter of the pair of guide rollers, and the position of the guide rollers controlling the width of the folded electrode mixture film; after folding, hot-pressing the folded electrode mixture film to defiber the PTFE binder along the second belt moving direction. [9] The method of claim 8, further comprising using at least one hot roller for hot pressing the electrode mixture. [10] The method of claim 9, further comprising feeding the electrode mixture into a hopper before feeding the electrode mixture to the first conveyor belt.

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