DE102008008483A1 - Solid polymer electrolyte-active substance, useful to produce a solid polymer electrolyte-foil for electrochemical battery device, comprises a polymer with a microporous structure and a metal salt e.g. solid/liquid-like lithium salt - Google Patents

Abstract

The invention relates to a solid polymer electrolyte material for an electrochemical battery device, a solid polymer electrolyte film for an electrochemical battery device, an electrochemical battery and a method for producing a solid polymer electrolyte film.
It is envisaged that the solid polymer electrolyte comprises a solid-like polymer component and a solid-like lithium salt component distributed within the solid-like polymer component, wherein a liquid-like lithium salt component is disposed at least in a part of the microporous structure.

Description

The The invention relates to a solid polymer electrolyte material for an electrochemical battery device with the in the preamble of claim 1 features, a solid polymer electrolyte film for an electrochemical battery device with the in The preamble of claim 9 mentioned features, an electrochemical Battery with the features mentioned in the preamble of claim 10 and a method for producing a solid polymer electrolyte sheet with the features mentioned in the preamble of claim 17.

The Lithium-ion batteries are very often used as energy storage systems for laptops, mobile phones or camcorders and the like used. Due to the high energy density up to 180 Wh / kg The lithium-ion batteries compared to conventional Batteries prevailed.

The anode of a lithium-ion battery may be made of metallic lithium or a compound that can store lithium ions. The cathode usually consists of lithium metal oxides of the general composition LiMO ₂ , where M is a placeholder for one of the metal elements such as Fe, Mn, Co, Va, Sn and so on. The electrolyte, which must have sufficient lithium-ion conductivity, may be liquid or solid. The liquid electrolytes contain solutions of LiPF ₆ or lithium phosphate (LiPON) in organic solvents. The high reactivity of elemental lithium (as a metal or intercalation compound) over organic solvents can lead to a reaction at high charge currents that destroys the electrolyte. In the case of liquid components in the electrolyte, gaseous products form, which lead to an increase in pressure in the battery. This pressure increase, which can lead to the destruction or explosion of the battery, generally represents a high security risk for battery operation.

at Lithium-ion batteries based on liquid electrolytes need to ensure the electrical insulation of the Electrolytes additionally separator films are introduced.

Around the disadvantages of lithium-ion batteries based on liquid Dealing with electrolytes has become very intense in recent years worked on lithium polymer batteries, either a reduced solvent content or no solvent at all.

Standard systems of polymer electrolyte batteries based on polyethylene oxide (PEO) show at room temperature too low a conductivity for use in a battery (see US 5,037,712 ). Other solid polymer systems such as polysiloxane (see US 5,123,512 ) or polyphosphazene (see US 4,840,856 ) show too low conductivity and film strength for use as electrolyte in a battery. The known in the art polymer electrolyte systems can not be produced on a large scale with film thicknesses <10 microns and at the same time great mechanical, thermal and electrochemical stability. Therefore, plasticizers and other additives are added to the polymer electrolyte. The so-called polymer gel electrolytes (see Japanese Pat JP 22453496 ) show increased ionic conductivities, but too little mechanical stability of the film for practical use in a battery. In addition, the same safety problems as with the liquid electrolytes again show up.

Necessary property improvements of the separator can be achieved by a composite component electrolyte separator. Separator films based on polyolefins such as polyethylene or polypropylene are currently available on the market. Essentially, two properties are important to the separators. On the one hand the wettability or surface tension, so that the electrolyte remains in the pores of the separator material, so that a sufficient ionic conductivity is formed, and on the other hand the thermal stability, so that a "thermal runaway" can be prevented good wettability with the electrolyte, but the thermal stability can be further optimized, in particular the decrease of the mechanical stability of the separator with the temperature deteriorates the system characteristics of a battery cell, as well as the separator film Separion ^® from Evonik, the temperatures> 200 ° C due to a withstand ceramic protection layer can not prevent due to changes in material at elevated temperature locally breakthroughs resulting in a short circuit and the mentioned "thermal runaway". The construction of so-called "separation electrolytes" seems to be a promising possibility to further improve the characteristics of a lithium-ion battery.

Basically, the use of solid polymer electrolytes in batteries also opens up a way to increase performance, which is not possible with liquid electrolytes. Due to the dendrite formation of the lithium at the anode, it is not possible to use lithium metal anodes with liquid electrolytes. Therefore graphite intercalation electrodes have been developed, in which the lithium can be incorporated. Lithium metal electrodes are characterized by a higher capacity than intercalation electrodes, resulting in a Leistungsver Improvement of the battery leads.

alternative The solid polymer electrolytes can increase the conductivity also be operated at higher temperatures, thereby but a loss of capacity or power density the battery is brought about.

The DE 10 2005 013 790 describes the preparation of a solid polymer electrolyte for a battery. Conductivities of> 10 ^-4 S / cm are achieved. However, the polymers used are not sufficiently stable thermally and electrochemically. In addition, film production with these polymers on an industrial scale is likely to be very expensive.

The DE 698 27 760 T2 discloses an electrolyte based on polyolefin or polypropylene, including the preparation of the polypropylene under catalyst conditions. The solution offered uses a porous polymer film impregnated with an electrolyte salt solution. The salt solutions used belong to alkali metal and alkaline earth metal salts such as LiF, Nal, LiI, LiClO ₄ , LiAsF ₆ , LiPF ₄ , LiCF ₃ SO ₃ and NaSCN.

Out DE 697 09 740 T2 For example, a substance usable in a nonaqueous electrolyte element of a lithium secondary cell and combining one or more lithium salts with a lithium polysulfide is known.

The DE 10 2005 013 790 B4 discloses a solid polymer electrolyte which does not contain liquid components at room temperature comprising a lithium component and a polymer component, wherein the polymer component comprises at least one polymer compound which interacts with the anions of the lithium salt component to promote dissociation of the lithium salt, the polymer electrolyte has an ionic conductivity at room temperature of at least 10 ^-4 S / cm without the addition of plasticizers or solvents.

From the DE 697 34 339 T2 the use of a halogen-substituted carbonic acid ester as a solvent of a non-aqueous electrolytic solution is known, whereby it is possible to improve the elastic modulus of the solid electrolyte and the retention of the solvent without lowering the ionic conductivity. It is a gel electrolyte with an improvement on the known drawbacks mentioned, but a polymer solid electrolyte with even more improved ionic conductivity and mechanical properties is still desired.

The DE 699 14 559 T2 discloses a solid polymer electrolyte prepared by using a multi-component copolymer in which propylene oxide and ethylene oxide are combined with another crosslinkable oxirane compound and mixing this copolymer with an electrolyte salt compound with addition of a plasticizer. The problems with the plasticizers have already been referred to elsewhere in this specification.

From the DE 10 2004 018 929 A1 For example, an electrolyte composition of an ionic liquid, a conductive salt, a film former, and a viscosity modifier is known. Since the electrolyte is liquid, this separators are required, which are associated with the known limitations described disadvantages.

The DE 699 23 138 T2 discloses a wound or laminated arrangement of anode, cathode and an intermediate solid electrolyte layer. Here it is intended to achieve the favorable by the winding spatial arrangement to achieve greater compactness and thus the power density of a battery.

In the DE 699 34 064 T2 discloses a solid polymer electrolyte in which, to achieve higher mechanical strength, at least two polymers enter into an interlocking polymer compound, which are equipped to bridge a plurality of compounds having bridging groups. A light metal salt is dissolved in one of the polymers. Although this mechanical properties have been improved, but the ionic conductivity of the electrolyte remains low.

The known solid polymer electrolytes are among the cooperating Aspects of ionic conductivity, film strength and chemical stability, however, as solid polymer electrolytes still insufficient for batteries.

Of the Invention is based on the object, solid or solid-like Polymer electrolytes with almost no liquid components, with High ionic conductivity and high mechanical strength, if possible already at room temperature. Furthermore, these should Polymer electrolytes thermally and electrochemically and in particular very stable with respect to lithium, yet electrically insulating and also cost-effective in an economical Scale to a film as thin as possible be processable as a solid polymer electrolyte film. Farther should be provided solid polymer electrolytes in electrochemical Devices such as batteries or accumulators, in particular in Lithium metal polymer batteries, lithium polymer batteries and lithium ion batteries be usable.

The The invention is based on a first invention Aspect of a solid polymer electrolyte material for a electrochemical battery device comprising at least one polymer having a microporous structure and a metal salt.

Thereby, that the solid polymer electrolyte is a solid-like polymer component and one distributed within the solid polymer component arranged solid-like lithium salt component, wherein at least in part of the microporous structure liquid-like lithium salt component is arranged, the objects of the present invention are achieved.

Further preferred embodiments of the invention will become apparent from the others, in the subclaims mentioned features.

In Preferred embodiment of the invention, the solid-like Lithium salt component and the liquid-like lithium salt component a same lithium salt substance.

According to one Another embodiment of the present invention form the solid-like Polymer component and the solid-like lithium salt component together at least one chemical compound.

According to one further advantageous embodiment of the present invention is the percentage by weight of the liquid-like Lithium salt component between 5 and 20%. In a more preferred Design is the percentage by weight of liquid-like lithium salt component about 12%.

Preferably is the polymer of the polymer component in a preferred embodiment of the present invention selected from the group of polyazoles.

According to another preferred embodiment of the present invention, the polymer of the polymer component is selected from the group of polyazoles. Preference is given to using the poly-m- (phenylene) 5,5-bibenzimidazole PBI having the structure:

Further more preferably, the PBI has an inherent viscosity, measured in a 1% weight percent solution in N, N-dimethylacetamide, of> 0.9 dl / g.

In a further preferred embodiment of the present invention, the lithium salt component is at least one of the inorganic anions LiPF ₆ , LiBF ₄ , LiAsF ₆ , LiClO ₄ and / or organic anions LiCF ₃ SO ₃ , Li (CF ₃ SO ₂ ) ₂ N, LiC ₄ BO ₈ (LiBOB).

The Invention is according to a second invention Aspect of a solid polymer electrolyte sheet for an electrochemical Battery device, wherein the inventive Problems are solved in that the solid polymer electrolyte film from a procured according to one of the embodiments described above Solid polymer electrolyte material is formed.

To a third aspect of the invention is the Invention of an electrochemical battery based on a Solid polymer electrolyte, the at least one arrangement of a first drain electrode, an anode, a first separator, a Electrolyte, a second separator, a cathode and a second Ableiterelektrode has. Alternatively, the present invention of an electrochemical battery based on a solid polymer electrolyte, the at least one arrangement of a first arrester electrode, an anode, an electrolyte, a cathode and a second drain electrode having, off. The tasks of the invention are solved in both alternative cases by as a solid polymer electrolyte, a solid polymer electrolyte film after the second invention described above Aspect is used.

In a particularly preferred embodiment of the present invention the anode is essentially formed of metallic lithium.

alternative In another embodiment, the anode may consist of an intercalation compound of Lithium be formed in carbon.

According to a further embodiment of the present invention, the cathode is essentially formed from a metal-oxide alloy of lithium having the formula description Li [M] O ₂ , where M denotes a placeholder for an alloying metal. More preferably, the alloying metal M is selected from a group Co, Mn, Fe, Ni.

According to a preferred embodiment of the present invention, the cathode of the battery device according to the invention is essentially formed from lithium iron phosphate LiFePO ₄ .

To a third aspect of the invention is the Invention of a process for producing a solid polymer electrolyte film for an electrochemical battery device made of a solid polymer electrolyte material out.

• – in einem ersten Schritt eine feststoffartige Polymer-Komponente in einem Lösungsmittel aufgelöst wird;
• – in einem zweiten Schritt in der aufgelösten feststoffartigen Polymer-Komponente eine vorbestimmte Menge der feststoffartigen Lithiumsalz-Komponente aufgelöst wird;
• – in einem dritten Schritt die erhaltene Lösung zu einem Dünnfilm verarbeitet wird;
• – in einem vierten Schritt eine so erhaltene Dünnfilmfolie getrocknet wird, bis das Lösungsmittel im Wesentlichen verdunstet ist und in der Dünnfilmfolie eine bleibende mikroporöse Struktur erzeugt wird;
• – in einem fünften Schritt in die Dünnfilmfolie eine flüssigstoffartige Lithiumsalz-Komponente, die aus einem in einem Lösungsmittel aufgelösten Lithiumsalz ausgebildet ist, derart eingebracht wird, dass die flüssigstoffartige Lithiumsalz-Komponente die mikroporöse Struktur im Wesentlichen ausfüllt.

The objects of the invention are procedurally achieved in that

• - In a first step, a solid-like polymer component is dissolved in a solvent;
• In a second step, in the dissolved solid-like polymer component, a predetermined amount of the solid-like lithium salt component is dissolved;
• - In a third step, the resulting solution is processed into a thin film;
• In a fourth step, a thin-film foil obtained in this way is dried until the solvent has substantially evaporated and a permanent microporous structure is produced in the thin-film foil;
• - In a fifth step in the thin film film, a liquid-like lithium salt component, which is formed from a solvent dissolved in a lithium salt, is introduced such that the liquid-like lithium salt component substantially fills the microporous structure.

According to one Another embodiment of the present invention, the solid-like Lithium salt component and the liquid-like lithium salt component formed from a same lithium salt substance.

In a preferred further embodiment of the method according to the present Invention form solid-like polymer component and a solid-like Lithium salt component with each other at least one chemical compound out.

Of the percent by weight of the liquid-like lithium salt component is in a preferred embodiment between 5 and 20%.

The Polymer of the polymer component is preferably selected from the group the polyazole selected.

Yet more preferably, the polymer of the polymer component in a Embodiment of the group of polyazoles, namely poly-m- (phenylene) 5,5-bibenzimidazole, designated PBI.

Further has the PBI in a further preferred, advantageous embodiment an inherent viscosity, measured in 1% percent by weight solution in N, N-dimethylacetamide, of> 0.9 dl / g.

According to a further embodiment of the method of the present invention, the lithium salt component is formed from at least one of the inorganic anions LiPF ₆ , LiBF ₄ , LiAsF ₆ , LiClO ₄ and / or organic anions LiCF ₃ SO ₃ , Li (CF ₃ SO ₂ ) ₂ N, LiC ₄ BO ₈ formed.

Based an example will now be a laboratory production the solid polymer electrolyte according to the invention explained.

2.5 g poly-m- (phenylene) 5,5-bibenzimidazole with an inherent Viscosity of 1.02 dl / g, measured on a 1% by weight Solution in N, N-dimethylacetamide, with 47.5 g of N, N-dimethylacetamide in a round bottom flask with an attached reflux condenser brought. The polymer solution is obtained by the above Mixture for 4 hours under reflux at T = 170 ° C is heated. With a propeller stirrer is the solution thereby constantly stirred. The obtained PBI solution is optionally filtered through a paper filter for cleaning. The resulting solution is treated with 0.014 g LiBOB (see above). dissolved in 10 ml of N, N-dimethylacetamide, and 20% by weight LiBOB based on PBI, offset. This polymer electrolyte solution is poured on a glass plate. The glass plate with applied Polymer electrolyte solution is kept in the drying oven for 4 hours dried at 200 ° C. The finished polymer electrolyte foil can then be removed from the glass plate. Subsequently The film is for one hour at 150 ° C in a drying oven of dried on both sides.

Of the Polymer electrolyte is mixed with a 10% weight percent solution of LiBOB in N, N-dimethylacetamide impregnated. The amount of impregnating solution is adjusted so that the bulk intake of LiBOB is preferably about 12% by weight is. This impregnation is at room temperature carried out.

The previous embodiments of the present invention are by way of example only, and not to be construed as limiting the present invention. The present invention can easily be applied to other applications become. The description of the embodiment is by way of illustration provided and not to the scope of the claims limit. Many alternatives, modifications and Variants are obvious to one of ordinary skill in the art without that he is the scope of the present invention would have to leave the, in the following claims is defined.

For the lithium-ion conductivity, a value of 1.3 × 10 ^-3 S / cm is obtained for an exemplary polybenzimidazole / lithium salt polymer electrolyte of the present invention at room temperature.

The solid polymer electrolyte according to the invention enables the use of metallic lithium electrodes and doing without special separators, allows a higher operating temperature and is processable into thin films with thicknesses below 10 microns, whereby electrochemical devices of higher power density can be implemented.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - US 5037712 [0006]
• US 5123512 [0006]
• US 4840856 [0006]
• - JP 22453496 [0006]
• - DE 102005013790 [0010]
• - DE 69827760 T2 [0011]
• - DE 69709740 T2 [0012]
• DE 102005013790 B4 [0013]
• - DE 69734339 T2 [0014]
• - DE 69914559 T2 [0015]
• DE 102004018929 A1 [0016]
• - DE 69923138 T2 [0017]
• - DE 69934064 T2 [0018]

Claims (24)

A solid polymer electrolyte material for an electrochemical battery device comprising at least one polymer having a microporous structure and a metal salt, characterized in that the solid polymer electrolyte comprises a solid-like polymer component and a solid-like lithium salt component distributed within the solid-state polymer component, at least a part of the microporous structure, a liquid-like lithium salt component is arranged. Solid polymer electrolyte material according to claim 1, characterized in that the solid-like lithium salt component and the liquid-type lithium salt component a have the same lithium salt substance. Solid polymer electrolyte material according to claim 1 or 2, characterized in that the solid-like polymer component and a solid-type lithium salt component with each other at least form a chemical compound. Solid polymer electrolyte material according to claim 1, 2 or 3, characterized in that the weight percentage the liquid-like lithium salt component between 5 and 20%. Solid polymer electrolyte material according to one of the claims 1 to 4, characterized in that the polymer of the polymer component is selected from the group of polyazoles. Solid polymer electrolyte material according to claim 5, characterized in that the polymer of the polymer component from the group of polyazoles a poly-m- (phenylene) 5,5-bibenzimidazole (PBI) is. Solid polymer electrolyte material according to claim 6, characterized in that the PBI has an inherent viscosity, measured in a 1% weight percent solution in N, N-dimethylacetamide, of> 0.9 dl / g. Solid polymer electrolyte material according to one of claims 1 to 4, characterized in that the lithium salt component of at least one of the inorganic anions LiPF ₆ , LiBF ₄ , LiAsF ₆ , LiClO ₄ and / or organic anions LiCF ₃ SO ₃ , Li (CF ₃ SO ₂ ) ₂ N, LiC ₄ BO. ₆ Solid polymer electrolyte film for an electrochemical Battery device, characterized in that the solid polymer electrolyte film of a solid polymer electrolyte material obtained according to any one of claims 1 to 8 is trained. Electrochemical battery based on a solid polymer electrolyte, comprising at least one arrangement of a first arrester electrode, a Anode, a first separator, an electrolyte, a second separator, a cathode and a second arrester electrode, characterized as a solid polymer electrolyte, a solid polymer electrolyte film used according to claim 9. Electrochemical battery based on a solid polymer electrolyte, comprising at least one arrangement of a first arrester electrode, a Anode, an electrolyte, a cathode and a second arrester electrode, characterized in that the solid polymer electrolyte is a solid polymer electrolyte film used according to claim 9. An electrochemical battery according to claim 10 or 11, characterized in that the anode consists essentially of metallic Lithium is formed. An electrochemical battery according to claim 10 or 11, characterized in that the anode consists of an intercalation compound is formed of lithium in carbon. Electrochemical battery according to one of claims 10 to 13, characterized in that the cathode is formed essentially of a metal-oxide alloy of lithium having the formula description Li [M] O ₂ , wherein M denotes a placeholder for an alloying metal. Electrochemical battery according to claim 14, characterized in that the alloying metal M is selected from a group Co, Mn, Fe, Ni is selected. Electrochemical battery according to one of claims 10 to 13, characterized in that the cathode is formed substantially from lithium iron phosphate LiFePO ₄ . A process for producing a solid polymer electrolyte sheet for a battery electrochemical device from a solid polymer electrolyte material, characterized in that - in a first step, a solid-like polymer component is dissolved in a solvent; In a second step, in the dissolved solid-like polymer component, a predetermined amount of the solid-like lithium salt component is dissolved; - In a third step, the resulting solution is processed into a thin film; In a fourth step, a thin-film foil obtained in this way is dried until the solvent has substantially evaporated and a permanent microporous structure is produced in the thin-film foil; - In a fifth step in the thin film film, a liquid-like lithium salt component, which is formed from a solvent dissolved in a lithium salt, is introduced such that the liquid-like lithium salt component substantially fills the microporous structure. Method according to claim 17, characterized in that that the solid-like lithium salt component and the liquid-like Lithium salt component formed from a same lithium salt substance become. Method according to claim 17 or 18, characterized the solid-like polymer component and a solid-like Lithium salt component with each other at least one chemical compound form. A method according to claim 17, 18 or 19, characterized characterized in that the percentage by weight of the liquid-like Lithium salt component is between 5 and 20%. Method according to one of claims 17 to 20, characterized in that the polymer of the polymer component is selected from the group of polyazoles. Method according to claim 21, characterized that as a polymer of the polymer component from the group of polyazoles a poly-m- (phenylene) 5,5-bibenzimidazole PBI was selected becomes. Method according to claim 22, characterized in that that the PBI an inherent viscosity, measured in a 1% weight percent solution in N, N-dimethylacetamide, of> 0.9 dl / g. Method according to one of claims 17 to 20, characterized in that the lithium salt component of at least one of the inorganic anions LiPF ₆ , LiBF ₄ , LiAsF ₆ , LiClO ₄ and / or organic anions LiCF ₃ SO ₃ , Li (CF ₃ SO ₂ ) ₂ N, LiC4BO _{6 is} formed.