JPH11144736A - Lithium ion electrolyte battery and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a physically and chemically stabilized lithium ion battery by an inorganic binder as a binder. SOLUTION: In a secondary electrolyte battery, especially a lithium ion electrolyte battery containing an inorganic binder, and a manufacture thereof, the binder material is evenly applied on a surface of a first and/or a second electrode, while mixing the binder material with the active material. The binder material is insoluble in the active material and is insoluble with respect to other related organic electrolytes.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates generally to secondary electrolyte batteries, and more particularly, to a lithium ion electrolyte battery containing an inorganic binder and a method for producing the battery.

[0002]

2. Description of the Related Art Lithium ion electrolyte batteries (eg, lithium ion secondary batteries) have been known in the art for several years. In addition, organic polymers (eg, PVD
Lithium batteries utilizing anode and cathode materials joined using F, EPDM, and some fluorine-containing copolymers) are likewise well known in the art.

[0003] Despite the well-established use of organic binders in lithium-ion batteries, there are some known limitations associated with battery (single / single cell) performance. Indeed, when utilizing an organic binder, some of the binder may be physically and / or chemically unstable due to dissolution in the electrolyte. This is because the electrolyte used in lithium ion batteries is also formed from organic compounds.
Thus, when such dissolution occurs, the binder (and the electrode) deteriorates prematurely, which can result in a loss of adhesion between the active material and its associated current collector / electrode.

In addition, when an electrode is prepared using an organic binder and is bonded to a current collector, it is necessary to use an organic solvent (actually, when the binder is mixed with an active material paste / paint). Required).
Therefore, any residual solvent must be removed after applying the mixed active material / binder to the current collector and before the battery fabrication is complete. Failure to do so will result in significant loss of battery capacity and reduced cycle life.

[0005]

Accordingly, it is an object of the present invention to provide a lithium ion electrolyte battery having an active material having excellent physical and chemical stability. It is a further object of the present invention to provide a unique method of manufacturing an electrode using an inorganic binder. These and other objects will become apparent in light of the present specification, claims, and drawings.

[0006]

SUMMARY OF THE INVENTION The present invention is directed to a lithium ion electrolyte battery having a first current collector and a second current collector each having a surface. Organic electrolytes include liquids, polymers, plastics,
Alternatively, it is selected from the group consisting of a gel electrolyte and used in connection with a particular electrode. At least one of the first and second current collectors has an active material applied to each surface. The active material is associated with a means for coupling the active material to the first or second current collector surface, respectively. The binder means does not dissolve in the active material or the organic electrolyte. Furthermore, the binder means and the active material associated therewith are mechanically and chemically stable during cycling and storage.

[0007]

DETAILED DESCRIPTION OF THE INVENTION In a preferred embodiment of the present invention, the binder means comprises an inorganic compound. The compound may include silicic acid, lithium salts, Li ₂ Si ₅ O ₁₁ (also known as lithium lithium silicate), as well as other inorganic compounds known to those skilled in the art, but require the binder means. Must satisfy the characteristics described above. In another preferred embodiment of the present invention, the binder means is associated with an active material for both the first and second current collectors. Of course, it is also conceivable to use it in connection with only one of the first or second current collectors.

The present invention also provides a) a step of mixing a binder material and an active material to coat a surface of at least one of the first and second current collectors, wherein the binder material is Insoluble in the active material, and also insoluble in the related organic electrolyte,
B) mechanically and chemically stable during cycling and storage); and b) at least one of the first and second current collectors has a mixed binder material and active Applying a substance, and c) associating an organic electrolyte selected from the group consisting of a liquid, polymer, plastic, or gel electrolyte with the first and second current collectors.
The present invention also covers a method for manufacturing a lithium ion electrolyte battery.

[0009] In a preferred embodiment of the method, the mixing step includes mixing an aqueous inorganic binder solution with a specific active material. In another preferred embodiment of the present invention, the present invention provides a method comprising: a) mixing a binder material and an active material to coat a surface of at least one of the first and second current collectors. B) chemically bonding the binder material and the active material; and c) chemically bonding the bonded binder material and the active material to the surfaces of the first and second current collectors, respectively. D) associating the bonded and bonded binder material and active material with an organic electrolyte selected from the group consisting of a liquid, polymer, plastic, or gel electrolyte; and e) dissolving the binder material in the organic electrolyte. To maintain the mechanical and chemical stability of the binder material, and to provide additional bonding during battery cycling and storage. And a step of holding the wear has been a binder material and the active material, and directed to a chemical process associated with the production of lithium-ion electrolyte batteries.

While the invention is susceptible to various forms of embodiment, it is shown in the drawings and further described herein is one specific embodiment, the disclosure of which may be Should be considered as illustrative of the principles of the present invention and it is to be understood that the invention is not limited to the embodiments shown. The electrolyte battery 10 is shown in FIG.
This battery has a first current collector
12 (anode), a second current collector 14 (cathode), and an electrolyte 16 are included. Although not shown, the electrolyte can be made from conventional compositions. Note that the electrolyte includes a liquid, a polymer, a plastic, or a gel. The present invention is not intended for use with glass or solid oxide electrolytes.

The current collector 12 is made of an inorganic binder material.
It is coated with an active electrode material 18 containing 19. Although one preferred inorganic binder, lithium lithium silicate, is disclosed for use in the present invention, those of ordinary skill in the art will appreciate that other conventional inorganic materials can be used as well. . However, such inorganic materials must exhibit the desired adhesion, chemical and physical stability required during battery cycling and storage.

FIG. 1 also shows a current collector 14. This current collector is coated with an active material 20, which does not contain an inorganic binder. Although the active material of the anode is shown without the use of inorganic binders, it will be understood by those skilled in the art that inorganic binders and mixtures of the anode, cathode, or both active materials are also contemplated. Wax (also will be shown by experiment).

As will be explained below, the use of inorganic binders preserves the physical and chemical stability in the cell during prolonged cycling and storage, thereby improving the performance of the cell. Know through experimentation. In practice, due to the insolubility of the inorganic binder in the organic electrolyte, it causes a bond with the particular active material, resulting in excellent adhesion of the mixed binder / active material to the particular current collector surface, In addition, there is no risk of deterioration occurring when the binder is partially or wholly dissolved in the electrolyte.

To demonstrate the benefits obtained from utilizing inorganic binders in lithium ion electrolyte batteries (and to disclose how to make such batteries), four independent experiments were performed. In these three experiments, an inorganic binder was used and one did not. For the first three experiments, a three-electrode battery was made with the following common features.

1. A graphite anode was prepared as follows.
1.0 g of lithium hydroxide (LiOH, manufactured by Aldrich)
In distilled water. 23.4 g of lithium polysilicate (Al
drich (20% aqueous solution) was mixed with this LiOH solution. Next, 45.0 g of graphite powder (Lonza's
KS-6) was added. To this was added 150 g of distilled water and the whole was mixed until a creamy paste was formed. After mixing, the paste was applied on copper foil (KISCO).
This copper foil (current collector) was approximately 12 microns thick. (The thickness of the actual coating was measured to be in the range of 30-50 microns after drying). The coated foil was then dried at ambient temperature for 1 hour, followed by a further 2 hour drying cycle in an oven heated to 100 ° C. After this initial heating step, the mixture was heated at 400 ° C. for a further 5 minutes under a stream of nitrogen to remove any residual water from the lithium polysilicate. Next, the heat-treated anode thus obtained was stored under reduced pressure and prepared for use.

2. A LiCoO ₂ cathode was made as follows. Dissolve 1.0 g of LiOH (Aldrich) in 21 g of distilled water and add 24 g of lithium polysilicate (Aldrich).
20% aqueous solution). 1.9 g graphite powder (KS-6 from Lonza), 2.9 g C-100 carbon black (Cheveron), and 85.6 g LiCoO ₂ powder (FMC), and 2.
0 g of Triton® X-100 (from Aldrich) were added together, followed by stirring and mixing until a creamy paste formed. Next, this paste was applied on an Al foil (current collector) (using an application plate). This Al foil had a thickness of about 25 μm. The thickness of the coating was measured to be approximately 30-70 microns after drying. (The primed Al foil was prepared as follows.
A suspension of lithium polysilicate and graphite was applied on Al foil. Next, pre-dry at 100 ° C for 1 hour, and finally 400 ° C
For 5 minutes. Typical subbing layer thickness was 2-4 microns. ) Next, apply the applied foil at ambient temperature for 1
After drying for an hour, an additional 2 hour drying cycle was performed in an oven heated to 100 ° C. After this initial heating step, the mixture was heated at 400 ° C. for a further 5 minutes under a stream of nitrogen to remove any residual water from the lithium polysilicate. Next, the heat-treated cathode thus obtained was stored under reduced pressure and prepared for use.

3. A control electrode was prepared as follows. 98 g of 2 g of poly (vinylidene fluoride) ("PVDF")
90.0 g of graphite powder (Lonz) was added to 100.0 g of a polymer solution prepared by dissolving in 1-methyl-2-pyrrolidone (“NMP”) solvent of
a) KS-6) was added. These ingredients were then mixed together until a creamy paste was formed. Next, this paste was applied on a copper foil. This copper foil was approximately 12 μm thick. (The undercoated copper foil was prepared as follows. First, a graphite-lithium polysilicate suspension was applied on the copper foil, and then pre-dried at 100 ° C. for 1 hour. Apply the coating under nitrogen flow for 40 minutes.
Heat at 0 ° C. for 5 minutes. The thickness of the undercoat layer on the copper foil was measured and was in the range of 2-4 microns. After the coating was completed, the NMP solvent was removed under reduced pressure at about 120 ° C. for about 12 hours. When measuring the typical thickness of the coating layer, 80-90
μm. After producing the above-mentioned electrodes, the following three experiments were performed.

Experiment No. 1 In this experiment, a graphite anode in a three-electrode battery manufactured as follows (the one manufactured as described above,
(Including a lithium polysilicate inorganic binder). The working electrode (the thickness of the coating layer is approximately 43 microns) was cut into a size of 2 × 2 cm ² . Lithium metal (also cut to a size of 2 × 2 cm ² ) was used as a counter electrode, and a lithium reference electrode (0.
(Cut to 5 × 0.5 cm ² ). Each electrode was separated using a glass fiber separator immersed in an electrolyte solution. As can be seen from FIG. 2, this battery has a charge / discharge current of 1 m
The cycle of A was 0.005 to 2.500 V. Voltage is 2.500V
, The voltage was held for 20 minutes. Calculated based on the results of this experiment, the first cycle Coulomb efficiency was approximately 82%.

Experiment No. 2 In this experiment, the above-described three-electrode battery was used for a test,
The electrode with the PVDF binder was evaluated. This organic binder was approximately 82 microns thick. As can be seen from FIG. 3, the cycling conditions for the battery were the same as above except that the charge and discharge current was 2 mA. When calculated based on the results of this experiment, the first cycle Coulomb efficiency was approximately 65%, much lower than the battery of Experiment No. 1 using an inorganic binder.

Experiment No. 3 In this experiment also, the above-described three-electrode battery was used for the test, but the purpose was to evaluate a LiCoO ₂ cathode (working electrode) having a lithium polysilicate binder. The thickness of the inorganic binder was measured to be about 39 μm.
In this experiment, as can be seen from FIG. 4, the three-electrode battery had a cycle of 3.200 to 4.200 V at a charging / discharging current of 1 mA. When calculated based on the results of this experiment, the Coulomb efficiency for the first cycle was approximately 91%, and for the subsequent cycles it was approximately 100%.

Experiment No. 4 In this experiment, a polylithium silicate binder was used.
A two-electrode cell (as opposed to a three-electrode cell) was made using a LiCoO ₂ cathode and a graphite anode also having a lithium lithium silicate binder. Furthermore, in this battery, ethylene carbonate and dimethyl carbonate (weight ratio 3: 2) using the electrolyte containing 1M LiAsF ₆ solution. This battery had a cycle of 2.700 to 4.150 V at a charge / discharge current of 1 mA. As can be seen from FIG. 5, the charging and discharging times were very close. This demonstrates that the use of an inorganic binder improves the Coulomb efficiency.
The foregoing description is merely illustrative and illustrative of the invention and is not intended to limit the invention.
However, while limited by the scope of the appended claims, one of ordinary skill in the art, upon reading the disclosure, will be able to make modifications and changes therein without departing from the scope of the invention.

[0022]

【The invention's effect】 [Brief description of the drawings]

FIG. 1 is a schematic diagram of a lithium ion electrolyte battery of the present invention.

FIG. 2 is a graph of the results of Experiment 1, especially showing voltage versus time.

FIG. 3 is a graph of the results of Experiment 2, specifically showing voltage versus time.

FIG. 4 is a graph of the results of Experiment 3, particularly showing voltage versus time.

FIG. 5 is a graph of the results of an experiment performed using a two-electrode battery using the inorganic binder of the present invention, and particularly shows voltage versus time.

[Explanation of symbols]

10 electrolyte battery, 12 first current collector (anode), 14 second current collector (cathode), 1
6 electrolyte, 18 active electrode material, 19 inorganic binder material, 20 active material

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Arthur A. Masco USA Massachusetts 01760 Natick Tamarack Road 20

Claims (11)

[Claims] 1. A first current collector and a second current collector each having a surface, an organic electrolyte selected from the group consisting of a liquid, polymer, plastic, or gel electrolyte, and an active material respectively applied to the surface. At least one of the first and second current collectors having a material; and the active material associated with binder means for binding the active material to a surface of the first or second current collector; A binder means that is insoluble in the organic electrolyte and mechanically and chemically stable during battery cycling and storage. 2. The lithium ion electrolyte battery according to claim 1, wherein said binder means contains an inorganic compound. 3. The lithium ion electrolyte battery according to claim 2, wherein said binder means includes a silicic acid and a lithium salt. 4. The lithium ion electrolyte battery according to claim 2, wherein said binder means includes Li ₂ Si ₅ O ₁₁ . 5. The lithium ion electrolyte battery according to claim 1, wherein said binder means is associated with said active material for said first and second current collectors. 6. The lithium ion electrolyte battery according to claim 1, wherein said second current collector comprises an anode made using graphite / carbon. 7. A step of mixing a binder material and an active material to coat a surface of at least one of the first and second current collectors, wherein
The binder material is at least insoluble in the organic electrolyte and is mechanically and chemically stable during battery cycling and storage); and at least one of the first and second current collectors. Applying the mixed binder material and active material to a surface of a current collector; and applying an organic electrolyte selected from the group consisting of a liquid, polymer, plastic, or gel electrolyte to the first and second electrolytes.
Associating with a current collector of the invention, comprising the steps of: 8. The method according to claim 7, wherein the mixing step includes mixing an inorganic binder aqueous solution and the specific active material. 9. The method according to claim 7, wherein the binder material contains an inorganic compound. 10. A method of mixing a binder material and an active material to cover a surface of at least one of the first and second current collectors, wherein the binder material and the active material are chemically combined. Chemically bonding the bonded binder material and active material to respective surfaces of the first or second current collector; and bonding and further bonding the binder material and the active material. Associating the active material with an organic electrolyte selected from the group consisting of a liquid, polymer, plastic, or gel electrolyte; and suppressing the dissolution of the binder material in the organic electrolyte to reduce the mechanical and mechanical properties of the binder material. It retains chemical stability and further binds and adheres the binder material and active material during battery cycling and storage. And a step of lifting, associated with the production of lithium-ion electrolyte battery chemical methods. 11. The method according to claim 10, wherein said binder material comprises an inorganic compound.