KR102434617B1 - 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 of manufacturing an electrode precursor (11, 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)
at least comprising
Prior to the heat treatment steps S12, S14, S22, and S24, the electrode paste 20 is provided with pore-forming particles 60 that are degassed and/or burned through the heat treatment steps S12, S14, S22, and S24. characterized.

Description

Method for manufacturing an electrode precursor, an electrode precursor, and a method for manufacturing an electrode paste

The present invention relates to a method for producing an electrode precursor according to the preamble of claim 1 of the present application and to an electrode precursor according to claim 12 . The present invention also relates to a method for producing 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 ensure 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 into an electrode paste, also referred to as a “slurry,” and then provided on a conductor film, and then for the electrode to be manufactured. further processed. However, its performance is still limited at present. This is due in particular to the high porosity in the solid battery electrode, which is established in the hitherto known manufacturing methods. Above all, the high porosity leads to a high interfacial resistance between the solid electrolyte and the active material, and leads to a decrease in the active material and the solid electrolyte present in the electrode, which in particular reduces the capacitance as well as the reduced energy density of the manufactured battery. also leads to

As disclosed for example in document US 2015 056 520 A1, the prior art currently focuses on the optimization of the ratio of active material to solid electrolyte in the electrode paste, for example, in order to improve the characteristic values of solid batteries and have.

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

The object of the present invention is to at least partially overcome the mentioned disadvantages of the prior art.

This task 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 developments of the invention appear in the dependent claims. The features individually enumerated in the claims can be combined with each other in a technically meaningful way, complemented by facts which will be explained from the description and/or details of the drawings, in which different variant embodiments of the invention are shown. .

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

- mixing or obtaining an electrode paste, and

- heat-treating the electrode paste to obtain an electrode precursor

includes at least

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

In the present case, an electrode precursor is to be understood as a battery electrode being manufactured. According to the present invention, the production of the battery electrode is terminated immediately before or with the installation of the battery electrode in the battery cell. However, it can also be considered that manufacturing is completely finished some time before this installation. Electrode precursors in the sense of the present invention are to be understood as intermediate products of the electrode manufacturing process, in particular in which electrode pastes have already been applied onto a conductor film, for example copper or aluminum. Preferably, it is also an intermediate product of an electrode manufacturing process that has already undergone a drying process, particularly preferably an intermediate product of a battery electrode manufacturing process that is present immediately before installation in a battery cell.

In the present invention, it should be understood that pore-forming particles are, for example, particles having a defined diameter and/or differently defined in shape, leaving a defined space in the electrode precursor upon combustion and/or degassing. The use of particles for porosity generation has the advantage that the porosity can be actively set over the range of the manufacturing process.

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

After or during the heat treatment step, the outgassed and/or burned particles leave defined pores in the electrode precursor. By possible subsequent penetration of the particle suspension, these pores can be filled with particularly suitable use of space. Accordingly, when selecting the pore-forming particles, the nature of the particle suspension, in particular the size and/or shape of the particles contained may be taken into account.

In one embodiment of the method according to the invention, the electrode paste contains particles of active material, the method comprising:

- impregnating 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 particles of the active material can be produced, which is then impregnated with a suspension with particles of solid electrolyte material. Particularly advantageously, the pore-forming particles in the electrode paste are tailored to the size and shape of the solid electrolyte material particles, so that the solid electrolyte material particles can completely or substantially completely fill the pores. In a particularly preferred embodiment, the size and shape of the pore-forming particles substantially correspond to the size and shape of the solid electrolyte material particles and/or integer multiples thereof. This results in an electrode precursor with a particularly low porosity at the end of the manufacturing process.

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

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

In this case, from the electrode paste in the manufacturing step, a porous matrix consisting substantially of a solid electrolyte material is produced, and the suspension with active material particles is then impregnated into this 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 correspond to the size and shape of the active material particles and/or integer multiples thereof. Thus, an electrode precursor with a particularly low porosity is produced at the end of the manufacturing process.

According to the present invention, the solid electrolyte particles may also be particles consisting of a solid electrolyte precursor material, for example Li ₂ S and/or P ₂ S ₅ , which is subjected to a further manufacturing step, in particular a heat treatment step, to form a solid electrolyte material. react only in

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

In a particularly preferred embodiment, the infiltrating step is carried out in vacuum. A vacuum is to be understood herein as a state in which a pressure lower than ambient pressure is present in the workpiece, ie in the electrode precursor being produced.

In a further embodiment, the suspension may be provided with a conductive additive. Conductive additives reduce the interfacial resistance between the active material and the solid electrolyte in the battery electrode. When the solid electrolyte suspension or the active material suspension is impregnated, this may be taken into account in the design and/or selection of the size of the pore-forming particles. Therefore, the conductive additive 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 method of manufacture, the thermally treating step is performed substantially at a temperature above the decomposition threshold of the pore-forming particles and/or below the decomposition threshold of the active material and/or the solid electrolyte material. Thereby, the pore-forming particles decompose during the heat treatment step and form pores that can substantially correspond to the size and shape of the pore-forming particles and/or integer multiples thereof. By carrying out the treatment steps at a temperature below the decomposition threshold of the active material and/or the solid electrolyte, these materials are advantageously prevented from decomposing and/or chemically converting during the heat treatment step.

In a group of embodiments, the electrode paste contains a binder material. In this case, the heat treatment step may also be performed at a temperature substantially above the decomposition threshold of the binder material. This advantageously results in the binder being discharged from the electrode precursor, thereby reducing the composition of the electrochemically inactive material in the electrode precursor. Particularly preferably, the binder material contains a material which acts as a conductive additive, said material remains after decomposition of the binder and/or forms a material which 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 carried out as a sintering process step. Through this, the particles present in the electrode paste constituting the structure of the electrode precursor are later combined with each other. This makes the binder completely or partially unusable. Particularly preferably, the sintering process step is carried out at a temperature above the decomposition threshold of the binder, so that substantially simultaneously with the subsequent bonding of the materials constituting the structure of the electrode precursor, in this case the unused binder is removed from the electrode precursor and , whereby the energy density of the battery cell prepared by the electrode precursor can be further increased.

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

In a group of embodiments, the pore-forming particle is a polymer-based particle. This has the advantage that it is known to use polymer-based materials in the manufacture of batteries, so that their 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 for the particles to be made of one or more of the following materials.

These materials have proven to be used in the manufacture of electrodes and can therefore be particularly well integrated into the manufacturing process.

The invention also relates to an electrode precursor for an anode or cathode, which is prepared and/or can be prepared with a method according to any one of the preceding claims.

The present invention also relates to a method for producing an electrode paste,

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

- obtaining a value for the expected porosity of the electrode manufacturable by the electrode paste to be produced;

- further identifying a target ratio of the active material to the solid electrolyte material based on the expected porosity;

- determining the target amount of the active material;

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

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

includes at least

This method produces an electrode paste which is particularly suitable for the method according to the invention for preparing electrode precursors. In this case, among other things, the ratio of the active material to the solid electrolyte is determined in the manufacturing process of the electrode precursor, based on the value for the expected porosity of the electrode producible by the electrode paste to be manufactured. In this case, the expected porosity of the electrode manufacturable by the electrode paste to be produced means the production of the electrode precursor according to the invention when the method according to the invention for producing the electrode precursor is carried out with a specific set of process parameters. It should be understood to be the porosity expected to be established at the end of the process. These values can be ascertained, for example, from a series of measurements with electrodes already manufactured and/or on the basis of models. According to the invention, said value is introduced into the method as an input parameter. However, it is also possible for the porosity to be determined instead on the basis of the known process parameters of the method according to the invention for preparing the electrode precursor in a method step instead.

In this case, the minimum ratio determines at least what concentration of active material should be present in the electrode paste, in which case the target ratio - defined by the identified minimum ratio - indicates what concentration of active material is actually set. . The values identified for the minimum ratio and the target ratio may not only be determined according to the specified variable, but may also be determined by other variables as well.

Values for the minimum and/or target ratio of active material to solid electrolyte material may be ascertained, for example, by means of a model or a property map. Such an embodiment has the advantage that it provides results particularly quickly and provides a low resource consumption for the computer system to be executed, and thus can be integrated particularly time-savingly and cost-effectively in the manufacture of batteries.

In a preferred embodiment, the method comprises the steps of obtaining a value for the energy density of a battery cell producible by the electrode paste to be produced, and further identifying a target ratio of the active material to the solid electrolyte material according to this energy density. is characterized by In this case, the energy density is generally specified quantitatively as the storable electrical energy per weight or volume of a battery cell that can be produced from an electrode paste produced by the method according to the invention for producing an electrode paste. However, energy density may also be understood and/or obtained as a qualitative expression. Thus, for example, they are classified as “energy cells”, ie battery cells designed to store in particular large amounts of electrical energy rather than providing in particular higher power, or as “power cells”, ie storing particularly large amounts of electrical energy. It is also possible to classify as a battery cell specifically designed to provide higher power than

In addition, the method for manufacturing the electrode paste includes the steps of: confirming a value for a percolation threshold from the size of the particle diameter of an active material, and further confirming a target ratio of the active material to the solid electrolyte material according to the percolation threshold It can be characterized as a step. The percolation threshold may be understood in this context as the concentration of active material in the electrode precursor at which the ionic and/or electronic conductivity of the electrode precursor and/or the electrode prepared therefrom increases rapidly. In such an embodiment, the target ratio of active material to solid electrolyte material may 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 high active material concentrations generally occur with increasing energy density within the battery cell. Conversely, when “power cell” information is obtained as energy density, an active material concentration that is substantially at the percolation threshold may be selected, since a higher active material concentration is less important here.

Other advantages and advantageous embodiments and developments of the present invention are explained on the basis of the following description with reference to the drawings.

1 shows an exemplary process of an embodiment of a method according to the invention;
2 shows an exemplary process of another embodiment of the method according to the present invention.
Fig. 3 schematically shows the confirmation rule of the target ratio of the active material to the solid electrolyte, depending on the expected porosity of the electrode producible by the electrode paste to be produced.
Fig. 4 schematically shows the confirmation rule of the minimum ratio of the active material to the solid electrolyte material according to the size of the particle diameter of the active material.

With reference 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 , the binder 90 , and the pore-forming material 60 , and additionally already applied on the conductor film 30 . The electrode precursor pre-stage 10 is prepared from. Then, this electrode precursor pre-stage is sintered and baked-out in a further method step S12. In this case, for example, process parameters such as temperature are set in such a way that the active material particles 40 form a sintered matrix with each other, while the pore former 60 and the binder 90 are decomposed or degassed. Then, in the permeation step S13, the solid electrolyte material suspension 70 is permeated into the resulting matrix under vacuum. 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 optionally performed process step (S14), the electrode precursor 11 is compressed again by heat press, and the remaining pores are reduced or substantially closed, so the electrode precursor having a low porosity according to the present invention (12) is generated.

2 depicts another exemplary process for another embodiment of the present invention. In this case, unlike shown in FIG. 1 , the electrode paste 20 containing the solid electrolyte material 50 is used instead of the active material. The process parameters of the method steps S21 to S24 are adapted accordingly to the changed composition of the electrode paste 20 . Finally, instead of the solid electrolyte material suspension 70 in the permeation step S23, 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 coordinated with each other.

Fig. 3 shows a confirmation rule of the target ratio of the active material to the solid electrolyte according to the expected porosity of the electrode that can be produced by the electrode paste to be produced. In this case, a porosity 111 of 5%, a porosity 112 of 10% and a porosity 113 of 20% are provided, where the region of densest packing possible 110 can be technically implemented within the electrode. none. In this case, according to the specific surface area 120 , a target ratio 100 of the active material to the solid electrolyte material at a given porosity 111 , 112 , 113 can be selected. The sizes plotted for specific surface area 120 and porosity 110 , 111 , 112 , 113 all represent characteristic values, which characteristic values indicate that the method according to the invention for producing an electrode precursor is a specific set of process parameters. 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 relationships shown are stored.

Fig. 4 further shows the confirmation rule of the minimum ratio of the active material to the solid electrolyte material according to the size of the particle diameter of the active material. Percolation thresholds 140 and 150 having an allowable error range according to the diameter 130 of the active material particles 40 provided for manufacturing the electrode paste 20 are shown. The relationship shown can be used in the method according to the invention for producing 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 of the upper limit of the tolerance range may be selected in the design for the "energy cell", and the value of the lower limit of the tolerance range may be selected in the design for the "power cell".

S11: drying step S12: sintering and baking-out step
S13: infiltrating step S14: heating/heat pressing step
S21: drying step S22: sintering and baking-out step
S23: Infiltrating step S24: Heating/heat pressing step
10: electrode precursor pre-stage
11: Electrode precursor after the step of infiltrating
12: electrode precursor after 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 [volume %]
110: dense packing 111: 5% porosity
112: 10% porosity 113: 20% porosity
120: specific surface area [10 ⁵ m2/m3] 130: particle diameter [㎛]
140: percolation threshold [volume % active material]

Claims (15)

A method for producing an electrode precursor (11, 12), comprising:
- 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 manufacturing method of the electrode precursor comprising at least,
Before the heat treatment step (S12, S14, S22, S24), the pore-forming particles 60 and the binder material 90, which are degassed or burned through the heat treatment step (S12, S14, S22, S24), the electrode paste ( 20), wherein the binder material (90) contains a material that acts as a conductive additive (80). The method according to claim 1, wherein the electrode paste (20) contains active material particles (40),
The manufacturing method is
- impregnating the solid electrolyte material particle suspension 70 (S13, S23)
Manufacturing method, characterized in that it further comprises. The method according to claim 1, wherein the electrode paste (20) contains solid electrolyte material particles (50),
The manufacturing method is
- Infiltrating the active material particle suspension 71 (S13, S23)
Manufacturing method, characterized in that it further comprises. The method according to claim 2 or 3, wherein the infiltrating step (S13, S23) is performed in a vacuum. 4. Process according to claim 2 or 3, characterized in that the suspension (70, 71) is provided with a conductive additive (80). 4. The active material (40) or solid electrolyte material according to any one of claims 1 to 3, wherein the heat treatment step (S12, S14, S22, S24) is performed at a temperature above the decomposition threshold of the pore-forming particles (60) or A process according to any one of the preceding claims, characterized in that it is carried out at a temperature below the decomposition threshold of (50). Production according to any one of the preceding claims, characterized in that the heat treatment step (S12, S14, S22, S24) is also carried out at a temperature exceeding the decomposition threshold of the binder material (90). Way. The method according to any one of claims 1 to 3, wherein the heat treatment step (S12, S22) is performed as a sintering process step (S12, S22). The method according to any one of claims 1 to 3, characterized in that the heat treatment step (S14, S24) is performed as a hot press step (S14, S24). The method according to any one of claims 1 to 3, wherein the pore-forming particles (60) are polymer-based particles. According to any one of claims 1 to 3, wherein the pore-forming particles (60),
- Cellulose
- saccharide
- Graphite
- carbon fiber
- Conductive Carbon Black
A manufacturing method, characterized in that the particles are made of one or more of the materials. An electrode precursor (11, 12) of an anode or cathode, which is or can be produced by the method according to any one of claims 1 to 3. delete delete delete

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