DE102020005083A1 - Stack battery with solid electrolyte - Google Patents

Abstract

The invention relates to a method for producing stacked batteries with a solid electrolyte, which comprises method steps for stacking, heating, evacuating, filling and cooling.

Description

The invention relates to a method for producing stacked batteries which contain a solid electrolyte. Stack batteries, which can also be referred to as bipolar batteries, are constructed according to a bipolar principle, which is known from the field of fuel cells. The stacked batteries consist of bipolar electrodes stacked one on top of the other. The bipolar electrodes consist of a carrier film made of either metal or a conductive plastic that is coated on both sides with active material. The property of a positive electrode is imprinted on one side of a respective bipolar electrode by the choice of material for the coating. The property of a negative electrode is imposed on the other side by the choice of material for the coating. The anode material layer and cathode material layer are generally congruent on a bipolar electrode or one of the electrodes (anode or cathode) protrudes over the other in both directions of extension, which may be necessary, for example, to avoid so-called lithium plating.

An electrolyte that allows ion exchange between opposing layers of anode material and cathode material of adjacent bipolar electrodes is required to form a galvanic cell. In the case of stacked batteries, the oppositely stacked arrangement of the bipolar electrodes forms a series connection of the galvanic cells, with n bipolar electrodes forming n-1 galvanic cells.

Stack batteries have the express advantage that the energy density is significantly higher compared to conventionally constructed batteries with the same basic chemistry, because fewer components are installed and dead volumes are largely excluded. In addition, the costs are often lower because the variety of parts is smaller, fewer parts are installed and fewer production steps are required for production.

In the area of lithium-ion batteries, the trend towards further increasing the energy content of batteries while at the same time increasing safety has led to efforts going in the direction that on the one hand the concept of the stacked battery is to be compared to the conventional design with individually housed and electrically connected batteries galvanic cells is becoming more widespread and, on the other hand, the development tendencies are geared towards using a solid electrolyte instead of the previous liquid electrolytes, which have good electrical properties but are regarded as safety-critical in the event of a fault. The use of solid electrolytes is expected to make it possible to use metallic lithium on the anode site instead of an intercalation material and thus achieve an additional increase in energy density.

There are different types of solid electrolytes. Three material classes are currently viewed as promising candidates for a commercial breakthrough: the very safe and handling-uncritical oxides, such as LLZO and LATP, the very conductive but difficult-to-handle thiophosphates, such as LPS, and the broad class of ion-conducting materials Polymers, e.g. PEO, n-PAN.

What oxidic and thiophosphate solid electrolytes have in common is that fundamental questions about the kinetics at the boundary layers (permeation and stability) between active materials and solid electrolyte have not been fully clarified and these technologies are therefore still in the research stage (DOI: 10.1149/1945-7111/ ab7f84). The problem of the boundary layer is also known for polymer electrolytes, whereby the compatibility with common active materials is better than with oxides and thiophosphates. The processing of the polymer electrolytes into galvanic cells is described in the patent literature, for example in DE102014113833A1 designates a method which provides for producing a free-standing film consisting of a polymer electrolyte by hot pressing and arranging this between an anode and a cathode. In this way, however, there is insufficient contacting of the active material surfaces. In addition, there are few methods available for integrating a polymer electrolyte, none of which solves the problem of contacting by sufficiently wetting the surfaces simultaneously for the anode side and the cathode side.

Proceeding from this prior art, a method for producing stacked batteries with a solid electrolyte is proposed which, through optimal wetting of the surfaces, generates a minimum contact resistance at the phase boundaries between the active materials and the solid electrolyte.

The object is achieved by a method for producing a stack battery (1), which consists of a recurring sequence of overlapping plate-shaped elements, namely the anode layers (12), the ion-blocking separating layers (14), the cathode layers (16) and the solid electrolyte layers (10), with seals (20) on the peripheral edges of the plate-shaped elements, characterized in that that the stacked battery is mechanically assembled in a first method step, the stacking step, in that a sequence of the following plate-shaped elements, anode layers, ion-blocking separating layers, cathode layers and additional porous separating layers with seals on the peripheral edges of the plate-shaped elements are assembled by alternating stacking of the plate-shaped elements and applying the seals, with at least one cannula being positioned at a predetermined position on the respective edges of the plate-shaped elements before or after the application of a seal. In a subsequent process step, the heating step, the sequence of the following plate-shaped elements, anode layers, ion-blocking separating layers, cathode layers and additional porous separating layers with seals on the peripheral edges of the plate-shaped elements is heated, for example by tactile heating by means of heating plates on the flat upper surface. and/or the flat, extended underside of the sequence of plate-shaped elements, by irradiating or flowing a warm gas around them. The temperature of the designated sequence of plate-shaped elements is heated to a temperature between 50°C and 300°C, particularly preferably to a temperature between 100°C and 150°C.

After the stacking step has taken place, in a further process step, the evacuation step, gas located in the areas between the ion-conducting separating layers and the seals is removed through the cannulas, for example by temporarily connecting vacuum generators to the outer ends of the cannulas.

After the evacuation step, in a further process step, the filling step, defined amounts of a liquefied solid electrolyte are introduced through the cannulas into the areas between the ion-conducting separating layers and the seals by liquid pumps or syringe machines or functionally similar devices being connected to the outer ends of the cannulas and the defined amounts of a liquefied solid electrolyte are introduced into the cannulas with excess pressure. The resulting presence of the solid electrolyte between the anode layers and the cathode layers forms the galvanic cells and the sequence of plate-shaped elements becomes a functional stack battery.

After the filling step, in a further process step, the cooling step, the stack battery is cooled down, for example by flowing a cold gas or by applying temperature-controlled plates, to a temperature of, for example, 25 °C or to the temperature before the heating step or to a different temperature definable temperature.

In an advantageous embodiment of the method according to the invention, in an additional method step, the evaporation step, which takes place after the filling step and before the cooling step, the cannulas are used to The amount of gas or vapor present is discharged into the environment, for example by connecting a vacuum pump to the outer end of the cannula. This evaporation step takes place over a defined holding time, during which the gas or vapor is removed.

In a further advantageous embodiment of the method according to the invention, the liquefied electrolyte is provided for the filling step by being converted into the liquid state of aggregation by heating in a storage container.

In a further advantageous embodiment of the method according to the invention, a force is exerted in the stacking direction of the stacked battery during the stacking step, during the heating and evacuation step, during the filling step, during the evaporation step and/or during the cooling step.

In a further advantageous embodiment of the invention, two or more cannulas are inserted into each circumferential seal of the stack battery for the purpose of evacuating and/or filling the stack battery with electrolyte.

In a further advantageous embodiment of the invention, the cannulas for evacuating and/or filling the stack battery with electrolyte consist of one of the following materials: polyetheretherketone (PEEK), polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE) or stainless steel 1.4404 and have a septum or a luer connector or a plug connector.

• 1 eine Stapelbatterie 1, die aus der wiederkehrenden Abfolge übereinander in folgender Reihenfolge gestapelter Schichten, i.e. Anodenschicht 12₁, 12₂, ... über Festelektrolytschicht 10₁, 10₂, ... über Kathodenschicht 16₁, 16₂, ... über Ionen-blockierender Trennschicht 14₁, 14₂, ..., besteht sowie aus Dichtungen 20₁, 20₂, ..., die einen freien Austausch der vorgenannten Schichten mit der Umgebung verhindern. Als Teil des Herstellungsprozesses der Stapelbatterie 1 wird erfindungsgemäß in einem Stapelschritt eine wiederkehrende Abfolge der folgenden Schichten, i.e. Anodenschicht 12₁, 12₂, ... über poröser Trennschicht 18₁, 18₂, ... über Kathodenschicht 16₁, 16₂, ... über Ionen-blockierender Trennschicht 14₁, 14₂, ... durch den Einsatz konventioneller Manipulations- und Positioniertechniken für folienartige Bauteile erzeugt.

The invention is described below with further features, details and advantages on the basis of the appended 1 explained. the 1 only illustrates exemplary embodiments of the invention. It shows

• 1 a stack battery 1, which consists of the recurring sequence of layers stacked one above the other in the following order, ie anode layer 12 ₁ , 12 ₂ , ... over solid electrolyte layer 10 ₁ , 10 ₂ , ... over cathode layer 16 ₁ , 16 ₂ , ... over ion-blocking separation layer 14 ₁ , 14 ₂ , ..., and gaskets 20 ₁ , 20 ₂ , ..., which prevent a free exchange of the aforementioned layers with the environment. According to the invention, as part of the manufacturing process of the stacked battery 1, in a stacking step, a recurring sequence of the following layers, ie anode layer 12 ₁ , 12 ₂ , ... over porous separating layer 18 ₁ , 18 ₂ , ... over cathode layer 16 ₁ , 16 ₂ , ... over ion-blocking separating layer 14 ₁ , 14 ₂ , ... generated using conventional manipulation and positioning techniques for sheet-like components.

During the stacking step, cannulas 30 ₁ , 30 ₂ , ... are also inserted into the seals 20 ₁ , 20 ₂ , ... so that these cannulas lie with one end inside the aforementioned, recurring sequence of layers and with the respective outer ends, the outer connections of the cannulas 95 ₁ , 95 ₂ , ..., lie outside. The outer connections of the cannulas 95 ₁ , 95 ₂ , ... are in the in 1 shown embodiment 3-way valves 60 ₁ , 60 ₂ , ..., connected with one of their terminals. With another of their connections, the 3-way valves 60, 60, ... are each connected to a filling pump 55 ₁ , 55 ₂ , ... to which a storage container 40 ₁ , 40 ₂ , ... is connected contained liquefied electrolytes 15 ₁ , 15 ₂ , ... and the other terminals of the 3-way valves 60 ₁ , 60 ₂ , ... Vacuum pumps 50 ₁ , 50 ₂ , ... are connected, so that in a stacking step subsequent evacuation step, gases that are located in and between the layers are discharged by sucking them through the cannulas 30 ₁ , 30 ₂ , . . .

In the exemplary embodiment shown, the recurring sequence of layers is surrounded by heating plates 90 ₁ , 90 ₂ , ... so that in a heating step following the stacking step, the sequence of layers is heated to a higher temperature, starting from an initial temperature, for example room temperature 25 °C is, for example, to a temperature of 130 °C by using the in 1 shown exemplary embodiment illustrated heating plates 90 ₁ , 90 ₂ , ... are heated and the recurring sequence of layers are heated by thermal conduction.

In the filling step according to the invention, after the evacuation step and heating step have been completed, _{liquefied electrolyte 15 1} , 15 ₂ , _. . . promoted between the layers of the recurring sequence of layers.

In a cooling step that follows the filling step, in the exemplary embodiment shown, the temperature of the recurring sequence of layers is also reduced by lowering the temperature of the heating plates, whereby the solid electrolyte layers 10 ₁ , 102 , Evaporation step Solvent components in the liquefied electrolyte 15 ₁ , 15 ₂ , ... are evaporated and removed via the cannulas 30 ₁ , 30 ₂ , ... and vacuum pumps 50 ₁ , 50 ₂ , ..., whereby the liquefied electrolyte 15 ₁ , 15 ₂ , ... gradually stagnates, whereby the solid electrolyte layers 10 ₁ , 102 , ... are formed. After the remaining solvent components have been expelled, in the final cooling step the temperature of the stacked battery 1 is reduced again, for example to room temperature 25°C.

Reference List

1

stack battery

101, 102,

solid electrolyte layer

121, 122,

anode layer

141, 142,

Ion-blocking separating layer

151, 152,

liquefied solid electrolyte

161, 162,

cathode layer

181, 182,

porous separating layer

201, 202,

poetry

301, 302,

cannula

401, 402,

storage container

501, 502,

vacuum pump

551, 552,

filling pump

601, 602,

3-way valve

901, 902,

hotplate

951, 952,

outer connection of the cannula

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• DE 102014113833 A1 [0006]

Claims (7)

Method for producing a stack battery (1), which consists of a recurring sequence of overlapping plate-shaped elements, namely the anode layers (12 ₁ , 12 ₂ , ...), the ion-blocking separating layers (14 ₁ , 14 ₂ , ...), the cathode layers (16 ₁ , 16 ₂ , ...) and the solid electrolyte layers (10 ₁ , 10 ₂ , ...), with gaskets (20 ₁ , 20 ₂ , ...) at the peripheral ones Edges of the plate-shaped elements, characterized in that a. in a first process step, the stacking step, a recurring sequence of mutually overlapping, plate-shaped elements, namely the anode layers (12 ₁ , 12 ₂ , ...), the ion-blocking separating layers (14 ₁ , 14 ₂ , ...). ), the cathode layers (16 ₁ , 16 ₂ , ...) and additional porous separating layers (18 ₁ , 18 ₂ , ...), with seals (20 ₁ , 20 ₂ , ...) at the peripheral edges of the plate-shaped elements is produced by alternately stacking the plate-shaped elements and applying the seals (20 ₁ , 20 ₂ , ...) and when applying the seals (20 ₁ , 20 ₂ , ...) cannulas (30 ₁ , 30 ₂ , .. .) In the seals (20 ₁ , 20 ₂ , ...) are inserted and b. in a further process step, the heating step, which takes place after the stacking step, the recurring sequence of mutually overlapping, plate-shaped elements, namely the anode layers (12 ₁ , 12 ₂ , ...), the ion-blocking separating layers (14 ₁ , 14 ₂ , ...), the cathode layers (16 ₁ , 16 ₂ , ...) and additional porous separating layers (18 ₁ , 18 ₂ , ...), with gaskets (20 ₁ , 20 ₂ , ...) is heated at the peripheral edges of the plate-shaped elements, for example from 25 °C to a temperature between 100 °C and 150 °C, and in the anode layers (12 ₁ , 12 ₂ , ...), the cathode layers (16 ₁ , 16 ₂ ,...) and the porous separator layers (18 ₁ , 18 ₂ , ...) contained and by the ion blocking separator layers (14 ₁ , 14 ₂ , ...) and the gaskets (20 ₁ , 20 ₂ , ...) included and c. in a further process step, the evacuation step, which takes place after the stacking step, amounts of gas contained in the anode layers (12 ₁ , 12 ₂ , ...), the cathode layers (16 ₁ , 16 ₂ , ...) and the porous separating layers ( 18 ₁ , 18 ₂ ,...) and enclosed by the ion-blocking separators (14 ₁ , 14 ₂ ,...) and the gaskets (20 ₁ , 20 ₂ ,...), by creating a Vacuum by evacuating through the cannulas (30 ₁ , 30 ₂ , ...) are led out d. in a further process step, the filling step, which is arranged after the evacuation step, through the cannulas (30 ₁ , 30 ₂ , ...) into the ion-blocking separating layers (14 ₁ , 14 ₂ , ...) and the Seals (20 ₁ , 20 ₂ , ...) enclosed areas defined amounts of a liquefied solid electrolyte (15 ₁ , 15 ₂ , ...) are pumped, which is formed from a molten, thermoplastic polymer with ion-conducting properties or a Molten, thermoplastic polymer mixture with ion-conducting properties, for example of succinonitrile and polyacylonitrile, with conducting salts dissolved therein, for example lithium bis(trifluoromethanesulfonyl)imide (LiTFSI for short), or of a dispersion consisting of solid electrolyte particles and a solvent, and e. in a further process step, the cooling step, which is arranged after the filling step, the recurring sequence of mutually overlapping, plate-shaped elements, namely the anode layers (12 ₁ , 12 ₂ , ...), the ion-blocking separating layers (14 ₁ , 14 ₂ , ...), the cathode layers (16 ₁ , 16 ₂ , ...) and additional porous separating layers (18 ₁ , 18 ₂ , ...), with gaskets (20 ₁ , 20 ₂ , ... ) at the peripheral edges of the plate-shaped elements and the liquefied solid electrolyte (15 ₁ , 15 ₂ , ...) contained therein is cooled, for example to 25 °C. Method for producing a stack battery (1). claim 1 , characterized in that in an additional process step, the evaporation step, which takes place after the filling step and before the cooling step, over a holding time by creating a vacuum by evacuating through the cannulas (30 ₁ , 30 ₂ , ...) gas and vapor quantities are led out, which are caused by evaporation or boiling in the areas enclosed by the ion-blocking separating layers (14 ₁ , 14 ₂ , ...) and the seals (20 ₁ , 20 ₂ , ...). Method for producing a stack battery (1). claim 1 , characterized in that the liquefied solid electrolyte (15 ₁ , 15 ₂ , ...) liquefied by heating and in a temperature-controlled storage container (40 ₁ , 40 ₂ , ...) for the filling step is provided. Method for producing a stack battery (1). claim 1 and 2 , characterized in that during the stacking step, during the heating and evacuation step, during the filling step, during the evaporation step and/or during the cooling step, a force is exerted in the stacking direction of the stacked battery (1). Stack battery (1) after claim 1 , characterized in that in each seal (20 ₁ , 20 ₂ , ...) two or more cannulas (30 ₁ , 30 ₂ , ...) are inserted. Method for producing a stack battery (1). claim 1 and 5 , characterized in that in the filling step simultaneously through a number of cannulas (30 ₁ , 30 ₂ , ...) in the of the ion-blocking separating layers (14 ₁ , 14 ₂ , ...) and the areas enclosed by the seals (20 ₁ , 20 ₂ , ...) defined amounts of a liquefied solid electrolyte (15 ₁ , 15 ₂ , ...) are pumped in and through a further number of cannulas (30 ₁ , 30 ₂ , ...) the areas enclosed by the ion-blocking separators (14 ₁ , 14 ₂ , ...) and the gaskets (20 ₁ , 20 ₂ , ...). to be evacuated. Stack battery (1) after claim 1 , characterized in that the cannulas (30 ₁ , 30 ₂ , ...) are made of plastic, for example polyetheretherketone (PEEK), polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), or metal, for example stainless steel 1.4404, and on the outside Connection of the cannulas (95 ₁ , 95 ₂ , ...) each have a septum or a Luer connector or plug connector.

Images