KR20200055652A - Method for manufacturing an electrode precursor and electrode precursor and method for manufacturing an electrode paste - Google Patents

Abstract

The present invention relates to a method for manufacturing electrode precursors (11, 12), comprising, at least, a step of mixing or obtaining an electrode paste (20) and steps (S12, S14, S22, S24) of treating the electrode paste (20) with heat to obtain the electrode precursors (11, 12). Before the heat treatment steps (S12, S14, S22, S24), pore-forming particles (60) which are degassed and/or burned through the heat treatment steps (S12, S14, S22, S24) are provided to the electrode paste (20).

Description

Manufacturing method of electrode precursor and manufacturing method of electrode precursor and electrode paste {METHOD FOR MANUFACTURING AN ELECTRODE PRECURSOR AND ELECTRODE PRECURSOR AND METHOD FOR MANUFACTURING AN ELECTRODE PASTE}

The present invention relates to a method for manufacturing an electrode precursor according to the preamble of claim 1 of the present application and an electrode precursor according to claim 12. In addition, the present invention relates to a method for manufacturing an electrode paste according to claim 13 of the present application.

Lithium ion batteries are often used as energy sources in the entertainment industry and electric vehicles. Here, in particular, solid-state batteries guarantee high safety, longevity and energy density. Solid battery electrodes are generally made of an active material, a solid electrolyte, a binder, and a conductive additive, which are first mixed with an electrode paste, also referred to as "slurry," and then provided on a conductor film, and then for the electrode to be produced. Further processing. However, its performance is still limited. This is due in particular to the high porosity in solid-state battery electrodes, which is established in the production methods known so far. Above all, the high porosity induces a high interfacial resistance between the solid electrolyte and the active material, and leads to a reduction in the active material and the solid electrolyte present in the electrode, which in particular reduces the energy density as well as the reduced capacitance of the manufactured battery. Leads to.

As disclosed, for example, in document US 2015 056 520 A1, the prior art currently focuses on optimizing the ratio of the active material to the solid electrolyte in the electrode paste, for example to improve the characteristic value of the solid battery. have.

It is also known from document DE 10 2016 220 675 A1 that the active material is introduced into the interstitial space of the battery electrode precursor.

It is an object of the present invention to at least partially overcome the stated shortcomings of the prior art.

This object is achieved by a method having the features according to claims 1 and 13 of the present application and an electrode precursor according to claim 12. Advantageous development examples of the invention are indicated in the dependent claims. The features listed individually in the claims may be combined with each other in a technically meaningful manner, supplemented by details of the drawings and / or facts to be described from the detailed description, wherein another variant embodiment of the invention is shown. .

The method according to the present invention is a method for producing an electrode precursor,

-Mixing or obtaining electrode paste, and

-Heat-treating the electrode paste to obtain the electrode precursor

It includes at least.

The method is characterized in that, prior to the heat treatment step, pore forming particles that are degassed and / or burned through this heat treatment step are provided to the electrode paste.

In this case, the term electrode precursor should be understood as the battery electrode being manufactured. According to the present invention, the manufacture of the battery electrode is ended just before installing the battery electrode in the battery cell or with the installation of the battery electrode. However, it can also be considered that manufacturing is completely ended before some time for this installation. In the sense according to the invention, it should be understood that the electrode precursor is an intermediate product of the electrode manufacturing process, in particular the electrode paste is already applied on a conductor film, for example copper or aluminum. Preferably, it is also an intermediate product of the electrode manufacturing process that has already undergone a drying process, particularly preferably an intermediate product of the battery electrode manufacturing process that is present immediately before installation in the battery cell.

In the present invention, the pore-forming particles should be understood as particles that have a defined diameter and / or a different shape, for example, leaving a defined space in the electrode precursor during combustion and / or degassing. The use of particles for porosity generation has the advantage that porosity can be actively set within the scope of the manufacturing process.

Providing the pore-forming particles in the electrode paste may mean, in the sense according to the invention, that the electrode paste in which the pore-forming particles are present is obtained and / or selected and / or actively mixed.

The degassed and / or burned particles after the heat treatment step or during the heat treatment step leave defined pores in the electrode precursor. By possible future penetration of the particle suspension, these pores can be filled under particularly suitable space use. Thus, when selecting pore-forming particles, the nature of the particle suspension, particularly the size and / or shape of the particles contained, can be taken into account.

In one embodiment of the method according to the present invention, the electrode paste contains the active material particles, and the manufacturing method comprises:

It characterized in that it further comprises the step of infiltrating the solid electrolyte material particle suspension.

It should be understood that the electrode paste used to prepare the electrode precursor contains an active material. During manufacture, from this electrode paste, a porous matrix consisting essentially of active material particles can be produced, and then a suspension with solid electrolyte material particles is permeated into this porous matrix. Particularly advantageously, the pore forming particles in the electrode paste are adjusted to the size and shape of the solid electrolyte material particles, so that the solid electrolyte material particles can completely or substantially fill the pores. In a particularly preferred embodiment, the size and shape of the pore-forming particles substantially corresponds to the size and shape of the particles of the solid electrolyte material and / or integer multiples thereof. This produces electrode precursors with particularly low porosity at the end of the manufacturing process.

In a further embodiment, the electrode paste contains particles of solid electrolyte material, and the method of manufacture comprises:

-It characterized in that it further comprises the step of penetrating the active material particle suspension.

In this case, a porous matrix of substantially solid electrolyte material is produced from the electrode paste in the manufacturing step, and then a suspension with active material particles is penetrated into the porous matrix. In this case, particularly advantageously, the pore-forming particles are adapted to the size and shape of the active material particles in suspension. In a particularly preferred embodiment, the size and shape of the pore-forming particles substantially corresponds to the size and shape of the active material particles and / or integer multiples thereof. Thus, an electrode precursor having a particularly low porosity is produced at the end of the manufacturing process.

According to the invention, the solid electrolyte particles can also be solid electrolyte precursor materials, for example particles consisting of Li ₂ S and / or P ₂ S ₅ , which are further produced to form a solid electrolyte material, in particular a heat treatment step. Only responds.

As the active material, for example, LCO, NCM LFP or HV. Spinel can be used. The active material particles may also be provided with a coating consisting of, for example, LiNbO ₃ and / or NCM.

In a particularly preferred embodiment, the step of infiltrating is performed in vacuum. It should be understood that a vacuum here is a state in which a pressure lower than the ambient pressure is present in the work piece, that is, the electrode precursor being manufactured.

In a further embodiment, a conductive additive can be provided to the suspension. The conductive additive reduces the interface resistance between the active material and the solid electrolyte at the battery electrode. When a solid electrolyte suspension or an active material suspension is infiltrated, it can be taken into account when designing and / or selecting the size of the pore-forming particles. Thus, conductive additives can be optimally added between the active material and the solid electrolyte during the manufacturing process. As the conductive additive, for example, carbon black or acetylene black can be used.

In one embodiment of the manufacturing method, the heat treatment step is performed at a temperature substantially above the decomposition threshold of the pore-forming particles and / or a temperature below the decomposition threshold of the active material and / or solid electrolyte material. Through this, the pore-forming particles are decomposed during the heat treatment step, and pores capable of substantially corresponding to the size and shape of the pore-forming particles and / or integer multiples thereof are formed. By performing the treatment step at a temperature below the decomposition threshold of the active material and / or solid electrolyte, it is advantageously prevented that these materials are decomposed and / or chemically converted during the heat treatment step.

In the group of embodiments, the electrode paste contains a binder material. In this case, the heat treatment step can also be performed at a temperature substantially exceeding the decomposition threshold of the binder material. Advantageously through this, the binder is discharged from the electrode precursor, whereby the components of the electrochemically inert material in the electrode precursor are reduced. Particularly preferably, the binder material contains a material that acts as a conductive additive, which material remains after decomposition of the binder and / or forms a material that acts as a conductive additive during decomposition. Conductive carbon black can be produced, for example, by combustion of a cellulose-based binder.

Preferably, the heat treatment step is performed as a sintering process step. Through this, particles present in the electrode paste constituting the structure of the electrode precursor are combined with each other. Through this, the binder cannot be used in whole or in part. Particularly preferably, the sintering process step is performed at a temperature above the decomposition threshold of the binder, so that at a later time substantially at the same time as the bonding of the materials constituting the structure of the electrode precursor, in this case the unused binder is removed from the electrode precursor , Whereby the energy density of the battery cell produced by the electrode precursor can be further increased.

In another preferred embodiment, the heat treatment step is performed as a heat press step. This step can also be carried out in addition to the heat treatment step according to the invention which has already been carried out. Performing as a heat press step has the advantage that, in order to compress the electrode precursor to further reduce the residual porosity, this step is also often used basically during electrode manufacturing. Therefore, it is only necessary that the process parameters of the heat press step are adapted to, for example, pore forming particles.

In the group of embodiments, the pore forming particles are polymer based particles. This has the advantage that it is known to use polymer-based materials in battery manufacturing, and thus integration into the manufacturing process can be implemented particularly simply.

The pore-forming particles may be substantially or completely

-Cellulose

-Saccharide

-Graphite

-Carbon fiber

-Conductive carbon black

It is also possible that the particles are made of one or more of the materials.

These materials have been proven to be used in electrode manufacturing, and thus can be particularly well integrated into the manufacturing process.

The invention also relates to an anode or cathode electrode precursor which can be produced and / or produced by a method according to any one of the preceding claims.

In addition, the present invention relates to a method of manufacturing an electrode paste,

-Checking the minimum ratio of the active material to the solid electrolyte material according to the size of the active material particle diameter,

-Obtaining a value for an expected porosity of an electrode that can be produced by an electrode paste to be manufactured,

-Further determining a target ratio of the active material to the solid electrolyte material based on the expected porosity,

-Determining the target amount of active material,

-Identifying a target amount and target type of pore-forming particles, at least according to the target amount of the active material and the target ratio of the active material to the solid electrolyte material, and

-Mixing the electrode target with the identified target amount of active material and pore-forming particles

It includes at least.

This method produces an electrode paste that is particularly suitable for the method according to the invention for producing an electrode precursor. Above all, in this case, based on the value for the expected porosity of the electrode that can be produced by the electrode paste to be produced, the ratio of the active material to the solid electrolyte is determined in the process of manufacturing the electrode precursor. In this case, the expected porosity of the electrode that can be produced by the electrode paste to be produced is the production of the electrode precursor according to the invention when the method according to the invention for producing the electrode precursor is performed with a specific set of process parameters It should be understood that the porosity is expected to be set at the end of the process. These values can be confirmed, for example, from a series of measurements with electrodes already manufactured and / or based on the model. According to the invention, the value is introduced in the method as an input parameter. However, it is also possible that the porosity is instead determined based on the known process parameters of the method according to the invention for producing an electrode precursor in a method step.

In this case, the minimum ratio determines at least how much active material concentration should be present in the electrode paste, and in this case the target ratio-limited by the identified minimum ratio-indicates how much the active material concentration is actually set. . The values identified for the minimum ratio and the target ratio can be determined not only according to the designated variable, but also by other variables.

Values for the minimum ratio and / or target ratio of the active material to the solid electrolyte material can be confirmed, for example, by a model or a property map. This embodiment has the advantage that it can be particularly quickly and cost-effectively integrated into battery manufacturing, as it provides results quickly and provides low resource consumption to the computer system to be executed.

In a preferred embodiment, the method comprises obtaining a value for the energy density of a battery cell that can be produced by the electrode paste to be manufactured, and further determining the target ratio of the active material to the solid electrolyte material according to this energy density. It is characterized by. In this case, the energy density is generally specified quantitatively as storable electrical energy per weight or volume of a battery cell, which can be produced from the electrode paste produced by the method according to the invention for preparing the electrode paste. However, energy density can also be understood as a qualitative expression and / or obtained. Thus, for example, as a “energy cell”, ie, as a battery cell, specifically designed to store a lot of electrical energy, rather than providing a higher power, or as a “power cell”, ie a particularly large electrical energy storage It is also possible to classify as battery cells, specifically designed to provide higher power, than to do.

In addition, the method of manufacturing the electrode paste comprises: checking a value for a percolation threshold from the size of the active material particle diameter, and further checking a target ratio of the active material to a solid electrolyte material according to the percolation threshold Steps can be characterized. The percolation threshold can be understood in this context as the concentration of the active material in the electrode precursor that rapidly increases the ionic and / or electron conductivity of the electrode precursor and / or the electrode produced therefrom. In this embodiment, the target ratio of the active material to the solid electrolyte material can be determined in such a way that an active material concentration substantially above the percolation threshold is selected, for example when “energy cell” information is obtained as the energy density, This is because a high active material concentration generally occurs with increasing energy density in the battery cell. Conversely, if "power cell" information is obtained as the energy density, the active material concentration substantially lying at the percolation threshold may be selected, since high active material concentration is less important here.

Other advantages and advantageous embodiments and development examples of the present invention will be described based on the following description with reference to the drawings.

1 shows an exemplary process of an embodiment of the method according to the invention.
2 shows an exemplary process of another embodiment of the method according to the invention.
FIG. 3 schematically shows a rule for confirming a target ratio of an active material to a solid electrolyte according to an expected porosity of an electrode that can be prepared by an electrode paste to be manufactured.
Figure 4 schematically shows the rule of identification of the minimum ratio of the active material to the solid electrolyte material according to the size of the active material particle diameter.

Referring to the drawings, an embodiment of the method according to the invention is shown.

1 shows an exemplary process for a possible embodiment of the present invention. In this case, in the first drying step (S11), the electrode paste (20) containing the active material (40) and the binder (90) and the pore-forming material (60), and is already applied on the conductor film (30) The electrode precursor pre-stage 10 is prepared from. Subsequently, this electrode precursor pre-stage is sintered and baked out in a further method step S12. In this case, process parameters such as temperature are set in such a way that the active material particles 40 form a sintered matrix at the same time, while the pore former 60 and the binder 90 decompose or degas. Subsequently, in the permeation step (S13), the solid electrolyte material suspension 70 is permeated under vacuum to the resulting matrix. Since the size and shape of the pore-forming particles 60 are adapted to the particles present in the solid electrolyte material suspension 70, the solid electrolyte particles 50 almost completely fill the pores. Finally, in the optional process step (S14), the electrode precursor 11 is compressed once again by a heat press, and the remaining pores are reduced or substantially closed, so that the electrode precursor has low porosity according to the present invention. (12) is produced.

2 shows another exemplary process for another embodiment of the present invention. In this case, as shown in FIG. 1, an electrode paste 20 containing a solid electrolyte material 50 is used instead of the active material. The process parameters of the method steps S21 to S24 are thus adapted to the modified composition of the electrode paste 20. Finally, in the permeation step (S23), instead of the solid electrolyte material suspension 70, the active material suspension 71 is permeated. The size and shape of the pore-forming particles 60 in the electrode paste 20 and the size and shape of the active material particles 40 in the active material suspension 71 are also adjusted to each other.

FIG. 3 shows rules for confirming the target ratio of the active material to the solid electrolyte, according to the expected porosity of the electrode that can be prepared by the electrode paste to be produced. In this case, porosity 111 of 5%, porosity 112 of 10% and porosity 113 of 20% are provided, where the region 110 of the densest packing possible can be technically implemented within the electrode. none. In this case, depending on the specific surface area 120, the target ratio 100 of the active material to the solid electrolyte material may be selected at a given porosity 111, 112, 113. The sizes shown for specific surface area 120 and porosity 110, 111, 112, 113 all represent characteristic values, which are specific to a set of process parameters for the method according to the invention for producing electrode precursors. When performed by, it is expected to be set at the end of the manufacturing process of the electrode precursor according to the present invention, and is introduced as a method for manufacturing the electrode paste as a preset process parameter. The resulting ratio 100 of active material to solid electrolyte material can be read, for example, from a property map in which the depicted relationship is stored.

Figure 4 further shows the rule of identification of the minimum ratio of active material to solid electrolyte material, depending on the size of the active material particle diameter. Percolation thresholds 140 and 150 are shown with tolerances according to the diameter 130 of the active material particles 40 provided for manufacturing the electrode paste 20. The illustrated relationship can be used in the method according to the invention for manufacturing the electrode paste 20 to determine the minimum ratio of the active material 40 to the solid electrolyte material 50. In this case, a value for the upper limit of the tolerance range may be selected in the design for the "energy cell", and a value for the lower limit of the tolerance range may be selected for the design for the "power cell".

S11: Drying step S12: Sintering and baking-out step
S13: Step to infiltrate S14: Step to heat / heat press
S21: Drying step S22: Sintering and baking-out step
S23: Step to infiltrate S24: Step to heat / heat press
10: electrode precursor pre-stage
11: electrode precursor after the step of infiltrating
12: electrode precursor after the step of heating / heat pressing
20: electrode paste 30: conductor film
40: active material 50: solid electrolyte
60: pore former 70: solid electrolyte material suspension
71: active material particle suspension 80: conductive additive
90: binder
100: Ratio of active material to solid electrolyte [% by volume]
110: dense packing 111: 5% porosity
112: 10% porosity 113: 20% porosity
120: specific surface area [10 ⁵ ㎡ / ㎥] 130: particle diameter [㎛]
140: Percolation threshold [% active material by volume]

Claims (15)

As a method for manufacturing the electrode precursors 11 and 12,
-Mixing or obtaining the electrode paste 20, and
-Heat-treating the electrode paste 20 to obtain the electrode precursors 11 and 12 (S12, S14, S22, S24)
In the production method of the electrode precursor, including at least,
Prior to the heat treatment steps (S12, S14, S22, S24), providing the electrode paste 20 with pore-forming particles 60 that are degassed or burned through the heat treatment steps (S12, S14, S22, S24) The manufacturing method characterized by the above. According to claim 1, The electrode paste 20 contains the active material particles 40,
The manufacturing method
-Infiltrating the solid electrolyte material particle suspension 70 (S13, S23)
The manufacturing method further comprising a. The electrode paste (20) according to claim 1, wherein the electrode paste (20) contains solid electrolyte material particles (50),
The manufacturing method
-Infiltrating the active material particle suspension (71) (S13, S23)
The manufacturing method further comprising a. The method according to claim 2 or 3, wherein the step of infiltrating (S13, S23) is performed in a vacuum. Method according to claim 2 or 3, characterized in that the suspension (70, 71) is provided with a conductive additive (80). The method according to any one of claims 1 to 3, wherein the heat treatment step (S12, S14, S22, S24) is a temperature above the decomposition threshold of the pore-forming particles 60 or the active material 40 or solid electrolyte material The manufacturing method characterized in that it is carried out at a temperature below the decomposition threshold of (50). 4. The electrode material (20) according to any one of claims 1 to 3, wherein the electrode paste (20) contains a binder material (90), and the heat treatment steps (S12, S14, S22, S24) also comprise the binder material (90). The manufacturing method characterized in that it is carried out at a temperature exceeding the decomposition threshold of. The manufacturing method according to any one of claims 1 to 3, wherein the heat treatment steps (S12, S22) are performed as a sintering process step (S12, S22). The method according to any one of claims 1 to 3, wherein the heat treatment steps (S14, S24) are performed as heat press steps (S14, S24). The method according to any one of claims 1 to 3, wherein the pore-forming particles (60) are polymer-based particles. The method according to any one of claims 1 to 3, wherein the pore-forming particles (60),
-Cellulose
-Saccharide
-Graphite
-Carbon fiber
-Conductive carbon black
It is a manufacturing method characterized in that the particles made of at least one material. An electrode precursor (11, 12) of an anode or a cathode, which may or may be produced by the method according to any one of claims 1 to 3. In the manufacturing method of the electrode paste 20,
-According to the size of the active material particle diameter 130, checking the minimum ratio of the active material 40 to the solid electrolyte material 50,
-Obtaining a value for expected porosity (110, 111, 112, 113) of the electrode that can be produced by the electrode paste (20) to be manufactured,
-Further, based on the expected porosity (110, 111, 112, 113), checking the target ratio of the active material 40 to the solid electrolyte material 50,
-Determining a target amount of the active material 40,
-Confirming the target amount and target type of the pore-forming particles 60, according to at least the target amount of the active material 40 and the target ratio of the active material 40 to the solid electrolyte material 50, and
-Mixing the identified target amount of the active material 40 and the pore-forming particles 60 with the electrode paste 20
Manufacturing method comprising at least. 14. The method of claim 13, wherein the step of obtaining a value for the energy density of the battery cell that can be produced by the electrode paste (20) to be manufactured, and further, the active material (40) for the solid electrolyte material (50) according to the energy density The manufacturing method characterized in that the step of confirming the target ratio. 15. The method of claim 13 or 14, further comprising: identifying a value for a percolation threshold (140) from the size of the active material particle diameter (130), and additionally the percolation threshold (140). According to the manufacturing method characterized in that the step of confirming the target ratio of the active material 40 to the solid electrolyte material (50).

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