WO2002025752A1

WO2002025752A1 - Housing for electrochemical cells

Info

Publication number: WO2002025752A1
Application number: PCT/DE2001/003552
Authority: WO
Inventors: Tim Schäfer
Original assignee: Gaia Akkumulatorenwerke Gmbh
Priority date: 2000-09-23
Filing date: 2001-09-15
Publication date: 2002-03-28
Also published as: DE10047206A1; AU2001291634A1; DE10194033D2

Abstract

The invention relates to a housing for electrochemical cells, comprising pole passages, preferably in the cover, in particular for lithium-ion polymer batteries (LIB). The housing consists of a container, which is directly connected to a contact (an electrode) and of a cover comprising the same material, into which the opposing-pole contact (electrode) is introduced, protected by an insulating mass. The invention is characterised in that the container and its cover consist of aluminium or alloys thereof, that the container is hermetically sealed by the cover, that the opposing-pole contact (7) that runs through the housing is electrically and mechanically isolated from the container by an insulating mass (8), which has a melting point of between 300° and 600 °C and that feed pipes or sensors, which are likewise embedded in the insulating mass, are optionally introduced through the container wall or cover wall. The invention has particular advantages if a glass solder (soldering glass) is used as the insulating mass. The inventive solution has particular advantages for the assembly process, in particular of LIBs and produces cell units that are maintenance-free in the long-term and are sealed in relation to the environment.

Description

Housing for electrochemical cells

The invention relates to a housing for electrochemical cells with pole feedthroughs, preferably in the cover, in particular for lithium-ion polymer batteries (hereinafter also called LIB). These are, in particular, cell housings and pole feedthroughs in the finished cover for electrochemical cells. Each of them includes a polymer electrolyte that conducts lithium ions, two reversible electrodes that store lithium ions, and batteries that comprise one or more such cells, especially for those that use polymer electrolyte lithium batteries.

Batteries, accumulators and the like basically consist of a housing in which electrodes and an electrolyte are arranged. The term polymer electrolyte describes a technology in which the separator does not consist of an “inert”, porous film and an injected liquid electrolyte, but instead of ion-conducting polymers with an additional separator function. In order to be able to release the electrical voltage generated by the battery and the like, it is known that Poles, in particular lead poles, are passed through the cover of the housing A key quality feature of such batteries is a sealed pole feedthrough, ie this pole feedthrough should be electrolyte and gas tight over the entire life of the battery.

From US-Patent 6,033,800, US Patent 5,492,779 and US Patent 4,467,021 are containers or Einhausungsvaπ ^'distinctive known that must be separately sealed hermetically.

Pole bolts or contacts of the generic type are known from DE 195 36 683. From DE 198 04 963, pole bolts are known which are suitable for galvanic cells with non-aqueous electrolytes, in which a large number of current conductors (contact capabilities) of the electrodes are connected to the pole bolts. It is A ceramic is provided in the passage area of the pole bolt through the cell cover, which is in particular soldered to the cell cover.

In order to meet the quality requirements of the dense and stable pole bushings, it is also known between the pole and the cover in the area of the pole bushing to encapsulate or shed it with hard plastic. It is also known to additionally provide seals in the form of sealing rings, or seals made of Viton, Teflon, between the pole and the cover.

Due to the electrochemical requirements for the resistance of the material in galvanic cells with non-aqueous electrolytes, the positive pole bolt is preferably made of titanium or a titanium alloy. The known battery cups consist regularly of stainless steel (such as SUS 304, SUS 316 or SUS 318 or molybdenum and various alloys such as stainless steel). From DE 198 39211 cell covers are known which provide connections for the use of a refill, each cell having a cover and the refill connections being connected when the refill connection and / or electrolyte circulating means are installed.

A low internal resistance and improved storage behavior have a direct influence on the quality of the batteries (preservation of the nominal voltage, capacity). Contact problems of the active materials or collectors or oxidized (hydroxide) soiled battery sleeves can be mentioned as possible causes. To avoid this, it is known to provide notches. According to WO98 / 18170 it is known to coat the electrodes with a lacquer. Japanese patent H 9-171802 proposes organic coatings which are carbonated by heating and which then have further layers of chromium. DE 198 52 202 provides that particles of predominantly carbon are embedded in the galvanic coating. Disadvantages are known lead poles for LIB and separately sealed, hermetically sealed battery housings and troughs. Plastic solutions are not optimal because they are not permanently vapor-tight. Stainless steel and alloys made of it as material for battery cups are expensive and not cheap for LIB. Known ceramic connections tear off, and glass melts require very high temperatures, around 1500 ° C, are therefore disadvantageous. Contact problems resulting from chemical reactions such as oxidation reduce the quality of the batteries, none of the known solutions have proven to be advantageous for LIB, since in particular there was insufficient resistance and electrochemical compatibility. Likewise, a concept for a controlled LIB could not be implemented because sensor contacts and functions, in particular, could not be suitably implemented.

Therefore, the task was to develop a finished cover with contact part for LIB, other electrochemical cells and the like, optimized cell housings and pole feedthroughs. In particular, LIB should be contacted and housed, which have a so-called front-side contact. These are wound offset, so that the cell laminate, monofilar or bifilar, with protruding metallic edges of metallic or other suitable current collectors, primarily copper and aluminum foils, can be contacted in accordance with requirements. The solutions had to help optimize energy density, be durable, durable, and leakproof, and should not require separate housings such as troughs that had to be hermetically sealed. In order to get sealed bushings, it was up to the company to find alternatives to glazings that are particularly demanding at low temperatures. Also to ensure the quality to the extent that a lower internal resistance and improved storage stability can be achieved and controllable batteries can be supported.

These tasks are carried out in a housing for electrochemical cells, in particular for lithium-ion polymer batteries, which consists of a vessel which is directly connected to a contact (an electrode) and a cover made of the same Material in which the opposite pole contact (electrode) is inserted, protected by an insulating compound, is released when

- the vessel and its lid are made of aluminum or its alloys,

- the lid is hermetically sealed to the vessel,

- The opposite-pole contact leading through the housing is electrically and mechanically separated from the vessel by an insulating compound which has a melting point between 300 ° and 600 ° C and

- If necessary, fill pipes or sensors are passed through the vessel or lid wall, which are also embedded in the insulating material.

The vessel should preferably be designed as a cylindrical vessel (cup).

Economical, vapor diffusion-tight, light and seamless housings, which are also radiation-repellent and recyclable, can be produced according to the invention in particular from conventional aluminum, light metal and their alloys.

Cups of the generic type, round and out-of-round, in particular from conventional capacitor cups and the like, can be selected as cell containers or housings.

Such cups are usually manufactured industrially using the extrusion process and are available in appropriate quality. According to the invention, a particularly advantageous solution is seen in the use of so-called capacitor cups, which are often available industrially without additional tool costs.

1 shows such an embodiment.

A contact (1) is already incorporated in the cup base (11), which serves for contacting or fixing and can be provided in various ways, for example by means of threads, slots, bores, in order to enable better contacting. The advantage is to design this contact (1) so that it can serve as a carrier for the electronics, which is disadvantageous on the cover side (see FIG. 2) due to higher mechanical loads. The contacts (1 and 7) can also be further treated, for example galvanically, in order to create improved electrical connections. The cup base (11) can also be of the same thickness as the cup wall (2), and feedthroughs can also be made here which serve, for example, current sensor connections.

According to the invention, it is proposed that a conductive lacquer or adhesion promoter according to DE 100 30 571.7 is injected directly into the sleeves (FIG. 1) after the sleeves or cups have been produced and, if appropriate, freed from oil and resistance layers, such as aluminum oxide. This can be done in a simple manner as a possible further treatment using conventional paint guns.

Generally suitable are cans and containers, round and out of round, made of different materials and material combinations (also cans for food) as a battery container.

Soft drink cans and tin cans can be used, for example, which can be permanently closed using a simple machine (Lubeca). To do this, the lids are positioned and closed. The lids are fed automatically and can be pretreated if necessary. These containers are tightly manufactured using can closing machines, if necessary a sealant or sealing element can be incorporated. Adhesive techniques can also be used as locking technology and insulation of the bushings.

The structure of a battery cover according to the invention is outlined in FIG. 2.

It consists of a pole contact (7), which is passed through a cover and is preferably glazed (8) with glass solder, special connections for a current sensor (10) being provided. These can be glazed in one piece with the pole contact (7) or separately (8). Such implementation on the basis of glass solders could be produced with at least temperature resistance up to 150 ° C and pressure resistant up to 10 bar.

A preferred variant is that the opposite-pole contact in the interior of the housing is designed as a plate, so that the two contacts (anode and cathode) almost fill the housing base and housing cover.

The inside of the lid is deep-drawn (4) with an upstanding edge, preferably of the same wall thickness as the cup according to FIG. 2, which can be welded to the cup rim (3, 6) or hermetically sealed in another way. According to the invention, beads are incorporated in the lid base (9), which enable increased heat transfer and stabilize the lid according to FIG. 2.

In the glass solder (8), which holds the contact (7), is fixed and is hermetic, a rupture disc (12) can be incorporated for the safety of the battery if protection against excess pressure is required. Then there is no need for separate overpressure safety valves.

According to the invention, it is particularly advantageous if a glass solder (solder glasses) is used as the insulating material. These are glasses with low viscosity and low surface tension with a melting point between 420 ° and 520 ° C.

According to the invention, glass solder-like solder materials or composite solder with glass portions with melting points between 300 ° and 600 ° C. can also be used in the broadest sense.

According to the invention, it is advantageous to provide the glazing using commercially available glass solder (for example from TA 23 or PA 23 from AmeriGlas). If material combinations other than Cu / Al are to be provided, melting alloys such as Nicosil against glass solder and melting body should also be arranged. Such an alloy tube can be brazed to the Cu contact bolt (7).

So-called GTM (Glass to Metal) or glass / metal or GLTM (Glass Lot to Metal) or glass solder / metal or CTM (Ceramic to Metal) or ceramic / metal and plastic composites such as AL / PP, AL / PET and others used. In principle, pole feedthroughs (8) can also consist of epoxy glass hard fabric, laminated materials, mica products and mineral pressed materials, also of paper composites, whereby it must be differentiated to what extent a suitable technology and, depending on the application, a sufficient quality of the bushings with regard to resistance and diffusion tightness can be achieved

The contact part according to FIG. 2 consists of a round bolt with a contacting unit (5). This consists of a highly conductive material, preferably copper (it is particularly advantageous to use S-ECU material qualities, i.e. oxygen-free copper, deoxidized or not deoxidized (in accordance with DIN 1787)), and notches, structures, coatings can be provided to protect the Protect contact, serve as a guide or better contact. The contacting unit is preferably worked as a contact plate (5) which is correspondingly smaller in diameter than the cover (6) and thus offers suitable protection against short circuits. A variant is to provide this contacting plate with openings to make it lighter.

Figure 2 shows an advantageous solution as a battery cover bushing. The inner cylinder height (4) for the glazing (8) should, however, be chosen so that it receives a good circulation, as suggested in FIG. 2 with approximately 3.5 mm. It is advantageous to provide axial depressions in the inner cylinder or inner edge (4), which can be continuous. As proposed, these axial depressions for the sintered glass body are worked into the inner cylinder (4) in a collar-shaped manner. This makes glazing easier, since the glass solder (8) finds good resistance, which can be called the glass solder brake.

Instead of axial depressions, other design measures can be used, such as guides, vertical depressions and the like.

The cylinder surface (7) should have a roughness of Rz = 1.6 μm and the deviation from the cylinder should be less than 0.2.

In order to achieve improved short-circuit behavior, for example in the event of a crash, and to fix the winding, a non-conductive, temperature-resistant fixing and adhesive composition is preferably introduced into the distance between the contact plate (5) and the cup wall (2). Alternatively, adhesive tapes, preferably electrical adhesive tapes or foils, in particular PET (polyethylene terephthalate) foils or glass flow materials, can be used.

These then form an intermediate layer and prevent a short circuit, for example, in the event of deformation. The use of adhesives that do not start to harden due to the catalytic effect of the moisture contained in the air is particularly advantageous. Epoxy materials and the anaerobic adhesives described are gap-filling, temperature-resistant from -60 ° to +220 ° C, because the hardening process can be influenced or activated by heat, especially by activators or heat, these materials are well suited for fixing the cell laminate in the cup.

Even when the laminate is stretched for the first time, for example during formation, the material goes along with it, so that deformation or the like cannot occur or the laminate is damaged. One-component reaction adhesives based on acrylates have emerged as particularly suitable adhesive materials (for example from the Omni / Fit product line from Henkel). In this way, the contacting unit in particular can advantageously be fixed in a few seconds, for example by applying the adhesive. It is advantageous to use this fixing or Adhesives in that, to a certain extent, one measure improves the vibration resistance of the arrangement in the vibration test, reduces short-circuits and the contacting unit can be fixed quickly.

Rupture disks (12) as structural overpressure safeguards can be incorporated as required, as illustrated in FIG. 3, and pressure valves can also be expedient.

Filling nozzles known per se, which can be hermetically sealed, are arranged in order to provide an evacuation after the formation, so that formation gas can escape and afterwards there is still access. Sensor bushings are just as easy to manufacture. They serve the generation of measurement data, which are to be arranged essentially in the context of a so-called intelligent battery. According to a special embodiment, the glass bushing (8) or glass serves as a sensor element in that it generates excess pressure and, if necessary, eliminates it by bursting.

After construction, each battery cell, regardless of its chemical composition, needs a so-called formation. This is a phase of controlled charging and discharging, in which the later properties of the battery are decisively determined. In addition to the process of reversible energy storage, which will later ideally be the only process occurring, other processes also occur, such as the formation gas formation. These gases may have to be removed.

Fig. 3 shows an embodiment of a pressure sensor with a rupture disk (12) made of glass solder, which can be arranged so or directly on the contact part. According to system requirements or to gain knowledge, a so-called filler neck (10) or vacuum tube must be arranged. The rupture disc (12) can consist of the pole penetration material used as a predetermined breaking point, whereby one or more substances can also be installed. The use of glass solders (8) of the types described is particularly advantageous according to the invention. Vacuum tube or the filler neck or the like is worked according to FIG. 3 to fit the rupture disc or the pressure sensor.

4 shows a finished, optimized cell housing with pole feedthrough primarily for lithium-ion polymer batteries. A filler neck or vacuum tube (10) is arranged, the solution of the glazing (8) is particularly suitable for one or more sensor bushings, which can be incorporated according to the invention as contact wires that are glazed (8). Furthermore, there is a contact (7), here sketched with thread, glazed (8): The internal, hidden contact plate (5), which is firmly connected to the contact (7), serves to position the contact and fix the cell winder. The edge of the cover (6) is permanently hermetically connected to the cup wall (2) or the cup rim (3) by means of suitable welding processes or other suitable joining techniques.

An electronic battery management system (BMS) provides additional functions that contribute to the controllable battery, relieve the load on other systems and are particularly useful in high-current applications. The current sensor should deliver the necessary data precisely and reliably to the BMS. It is characterized by higher accuracy and lower power loss, and thus enables a more precise determination of the state of charge. Information about the state of charge, service life etc. of the battery should be made available to the user.

The battery receives "intelligence" from electronic components such as charging and power modules, and the current sensor to be integrated into the battery design, as described in DE 198 60 561.7.

The construction of different cell structures into modules has become simpler through the housing according to the invention, and the emergence of plasticizers or vapors, such as carbonate solvents, into the module housing, which could contain the sensitive electronics, is reduced to zero reduced. Furthermore, the use of different housing materials for the module housing, such as plastic, is permitted, and a hermetic seal is no longer required. The inventive solution brings some great advantages to the assembly process, especially from LIB. After all, it is a particular advantage to have a cell unit that is maintenance-free and tight to the outside in the long term.

The invention will be explained below for the special application of a battery in a "sandwich" arrangement:

The following lithium-ion polymer battery (LIB) creates a so-called gel electrolyte system. The polymer is the carrier for the high-boiling polar and aprotic electrolyte components (ethylene and propylene carbonate) in which a lithium conductive salt such as LIPF ₆ , lithium perchlorate or LiCF ₃ S0 _{3 is} dissolved. In contrast to the older "classic" solid polymer electrolyte system, the lithium ion conductivity is now determined by the liquid component and is> 1 mS / cm. The electrolyte system also serves as a separator between the electrodes. This electrolyte can therefore hardly flow and This particularly affects the seal. Lithium-manganese spinel (LiMn ₂ θ ₄ ) is used as the cathode active material.

Intercalation graphites are used as anode active material. In the electrodes, the polymer electrolyte acts as a binder between the electrochemically active particles. The electrode masses are applied as thin layers (50 - 250 μm) to metal foils, and the battery is manufactured in a "sandwich" arrangement. In contrast to liquid electrolyte systems, self-adhesive laminates are created. This eliminates the contact pressure required with fixed liquid electrolyte systems due to the winding and free design becomes possible.

The so-called cell winding results from the winding together of the three individual webs for anode, solid electrolyte and cathode (plus insulation film for monofilament winding). The protective films wrapped during the coating are removed. The contact is made on the respective coating free metal strips on the edge of the arrester foil. It takes place at the same time as the winding process using a friction welding process. Defined contact flags are attached to the metallic edge of the respective conductor foil in such a way that they come to lie on top of each other despite the variable winding circumference.

One electrode is in contact with the bottom of the housing, the other is in direct connection with the contact plate of the cover.

The lithium-ion polymer technology makes it possible to meet the demands of the market, e.g. the automotive industry, according to flexible design. The starting point are special, wound and contacted cells. The lamination and winding of the laminates allows for wide variations and modular construction of batteries for a wide variety of applications and performance areas. Furthermore, free shaping in flat cells of any size, in contrast to other battery systems, is feasible. This makes it possible for the device and battery to "fuse" to form a system with new, improved properties, for example by accommodating the battery as a housing component.

Exemplary lithium polymer cells are 207 mm high according to a special design, have a diameter of 85 mm with a weight of 2.12 kg, 3.8 V and a nominal capacity of 5 Ah (C5).

The sizes of the cells are variable, and special requirements can easily be taken into account. The following table shows an example of characteristic electrical data of such LIB: Lithium polymer cell

List of reference numbers

1 contact on the ground

2 cup wall

3 cup rim

11 cup base

4 edges, inside, cover

5 contact plate

6 lids

7 Contact in the lid

8 glass, glass solder

9 lid base

10 filler neck, sensor feedthrough

11 cup base

12 rupture disc

Claims

claims

1. Housing for electrochemical cells, in particular for lithium-ion polymer batteries, from a vessel that is directly connected to a contact (an electrode), and a cover made of the same material in which the opposite-pole contact (electrode) is protected by an insulating compound is introduced, characterized in that

- the vessel and its lid are made of aluminum or its alloys,

- the lid is hermetically sealed to the vessel,

2. Housing for electrochemical cells according to claim 1, characterized in that the vessel is designed as a cylindrical vessel (cup).

3. Housing for electrochemical cells, in particular for lithium-ion polymer batteries, according to claim 1 and 2, characterized in that the opposite-pole contact in the interior of the housing is designed as a plate, so that the two contacts (anode and cathode) housing bottom and almost fill the housing cover.

4. Housing for electrochemical cells according to one or more of claims 1 to 3, characterized in that a glass solder with a melting point between 420 ° and 520 ° C is used as the insulating mass.

5. Housing for electrochemical cells according to claim 1 to 4, characterized in that a glaslotähniicher solder material or composite solder with glass portions with melting points between 300 ° C and 600 ° C is used as the insulating mass.

6. Housing for electrochemical cells according to one or more of claims 1 to 5, characterized in that there is a rupture disc in the cover of the housing, which is connected to the insulating mass and the other entries in the housing (contact, filler tube or sensor) is.

7. Housing for electrochemical cells according to one or more of claims 1 to 6, characterized in that there is a pressure valve in the cover of the housing that connected to the insulating mass and the other entries in the housing (contact, filler tube or sensor) is.