JP2000182673A - Battery having controlled electrode surface, manufacture thereof and chemical process - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress gas generation due to decomposition of a solvent used in an electrolyte and decomposition of an additive during charging/discharging cycles or storage by providing a passivating means including an additive or a reducing additive associated with the surface of a metallic collector, and a means for substantially preventing gas generation. SOLUTION: In this battery, after a battery 110 is manufactured, a passivation layer 124 is formed by initial charging. After the initial charging, an additive is reduced near the interface between a surface 126 of a metallic collector 122 of a first electrode 112 and an electrolyte 116. In this reduction, it is included that the chemical structure of the additive is changed to become insoluble or the additive associates with the surface 126 of the metallic collector 122. The passivation layer 124 substantially prevents a solvent 118 in the electrolyte 116 from coming into contact with the surface 126 of the metallic collector 122. Therefore, the decomposition of the solvent is prevented and the gas generation in the battery 110 is substantially suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

FIELD OF THE INVENTION The present invention relates to batteries having a controlled electrode surface, and more particularly to the use of additives that are reduced in place to result from the decomposition of the solvent used in the electrolyte. The present invention relates to a lithium battery having a metal current collector which substantially prevents gas generation in a battery and substantially suppresses gas generation due to decomposition of an additive itself during charge / discharge cycles and storage of the battery. The invention further relates to the manufacturing method and the chemical process.

[0002]

2. Description of the Related Art Research and development of lithium ion batteries have been progressing for several years. Above all, research and development of lithium batteries using a liquid, gel, polymer or plastic electrolyte and using a metal current collector have been promoted. Although such an electrolyte can be used easily, it has been pointed out that a commercially available solvent used in the electrolyte decomposes during a charge / discharge cycle and storage of a battery.
In particular, when no conventional additives are present in the battery and no passivation layer is formed, the solvent reacts with the electrode interface,
Partially decomposes during battery charge / discharge cycles and storage.
This decomposition produces a significant amount of gas that affects battery performance, adversely affecting the electrochemical properties of the battery, especially Coulombic efficiency.

[0003] While conventional additives are used to form a passivation layer that substantially prevents contact between the solvent and the electrode, there are still problems with the conventional additives. That is, there is a problem that the conventional additive itself is decomposed during the charge / discharge cycle and storage of the battery, and this decomposition generates a large amount of gas in the battery that affects battery performance.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to substantially prevent gas generation in a battery due to the decomposition of a solvent used in an electrolyte, and to reduce the charge and discharge cycles of the battery and during storage. An object of the present invention is to provide a lithium battery having a metal current collector, in which gas generation due to decomposition of the additive itself is substantially suppressed.

[0005]

Means for Solving the Problems As a result of intensive studies to achieve the above object, the present inventors have found that a first electrode and a second electrode, an electrolyte, a specific additive and / or a reducing additive, It has been found that the above problem can be solved by a battery comprising the passivating means and the specific gas generation preventing means, and the present invention has been completed.

The present invention has been completed based on the above findings, and a first gist of the present invention is that at least one of the electrodes includes a first electrode and a second electrode each containing a metal current collector having one surface. An electrolyte containing at least one solvent, an additive and / or a reducing additive associated with the surface of the at least one metal current collector, a passivating means containing the additive or the reducing additive, and gas generation. Wherein the passivation means substantially prevents contact between at least one solvent in the electrolyte and the surface of the at least one metal current collector, Substantially preventing gas generation due to the decomposition of the solvent upon contact with the surface of the at least one metal current collector, wherein the gas generation prevention means is associated with an additive or a reducing additive and is used to charge the battery. Discharge cycle A controlled electrode surface which is a means for substantially preventing gas generation in the battery due to decomposition of the reducing additive on the surface of the at least one metal current collector during storage and storage. Exists in batteries.

In a preferred embodiment of the first aspect, the additive or the reducing additive is a means for improving the coulomb efficiency of the battery.

In another preferred embodiment of the first aspect, the Coulomb efficiency over the first to tenth cycles exceeds 85%. Further, the coulomb efficiency of the first cycle is 91% or more.

Another preferred embodiment of the first aspect further includes a means for substantially preventing the formation of dendrites near the surface of the metal current collector.

A second gist of the present invention is that (a) a step of manufacturing a first electrode and a second electrode including a metal current collector in which at least one electrode has one surface; and (b) first and second electrodes. 2
Associating at least one electrolyte comprising at least one solvent with the electrode; and (c) associating an additive with at least one electrode comprising at least one electrolyte or the metal current collector having one surface. And a method for manufacturing a battery.

A third gist of the present invention is that (a) a step of manufacturing a first electrode and a second electrode including a metal current collector in which at least one electrode has one surface; and (b) first and second electrodes. Associating at least one electrolyte comprising at least one solvent with the two electrodes; (c) associating an additive with the surface of the electrolyte or the at least one metal current collector; and (d) associating an additive with the at least one metal current collector. Forming a passivation layer between the surface of the metal current collector and the electrolyte, wherein the passivation layer forming step further comprises: (1) charging the battery (2) a step of substantially reducing an additive on the surface of the metal current collector to make the reduced additive substantially insoluble in the electrolyte; and (3) at least one solvent in the electrolyte and the at least one solvent. With two metal current collector surfaces A step of substantially preventing interaction, (4) charge-discharge cycle and during storage of the battery,
Substantially preventing gas generation within the battery due to decomposition of the reducing additive.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. The present invention is not limited to the embodiments and descriptions illustrated below, as the invention is capable of various embodiments.

FIG. 1 is a schematic view of a conventional battery before initial charging. As shown in FIG. 1, a conventional battery 10 before charging is:
Usually, it is composed of the first electrode 12, the second electrode 14, and the electrolyte 16. The electrolyte 16 includes a solvent 18 and a conventional additive 20.

FIG. 2 is a schematic diagram of a conventional battery after initial charging. As shown in FIG. 2, the conventional battery 10 after the initial charge
Consists of a first electrode 12, a second electrode 14, an electrolyte 16 and a passivation layer 20 '. The passivation layer 20 'is formed in part by the association of the conventional additive with the electrode prior to the interaction of the conventional additive with the solvent in the electrolyte. While such a passivation layer substantially prevents contact between the solvent and the electrode, the additive initiates decomposition during the charge and discharge cycle and storage of the battery, and a significant amount of gas that affects battery performance. Occurs.

FIG. 3 is a schematic diagram of the battery according to the present invention before the initial charging. As shown in FIG. 3, the battery 110 of the present invention before the initial charge generally has a first electrode 112 and a second electrode 11.
4 and the electrolyte 116. The electrode 112 includes a metal current collector 122. As the metal current collector, many metal species or metallic species can be used as long as they do not form an alloy or an interlayer compound with lithium, and specifically, it is preferably made of copper. Its thickness is usually 25 μm or less, preferably 1 to 25
μm.

The electrolyte 116 comprises a solvent 118 and an additive 12
0 is included. In the figure, the additive 120 is merely illustrative.
However, the additive 120 is initially associated with the electrolyte 116, but the additive 120 may be associated with the first electrode 112. As a related method between the additive 120 and the electrode, any of conventional methods such as spraying, rolling or coating may be used. If a substance that is substantially soluble in the electrolyte, such as succinic anhydride, is used as the additive, the additive may be mixed with the electrolyte at any stage using conventional mixing techniques.

Further, examples of the additives 120 include, but are not limited to, phosphites, carboxylate salts, thiophenes, and anhydrides, as exemplified in the following experimental examples. The properties of such additives are shown below.

1) It may be either soluble or insoluble in the related electrolyte before the reduction, and becomes substantially insoluble in the related electrolyte after the reduction.

2) It can be reformed to a reduced state substantially without generating gas.

3) A passivation layer is formed on the surface of the metal current collector to substantially prevent contact between the solvent in the electrolyte and the surface of the metal current collector, resulting from the interaction between the solvent and the electrode surface. Prevents decomposition and decomposition and outgassing of the uncontrolled passivation layer.

4) A battery having an increased first cycle Coulomb efficiency can be formed as compared with a battery without an additive.

5) The formation of dendrites in the battery is substantially prevented.

The additives having such properties include HTP (3-hexylthiophene, chemical formula 1) represented by the following chemical structural formula, TPP (triphenyl phosphite,
Chemical formula 2), A-4 (aldrithiol, chemical formula 3),
SA (succinic anhydride, chemical formula 4), DSA (2-dodecene-1-yl succinic anhydride, chemical formula 5), THPA (cis-1,2,3,6-tetrahydrophthalic anhydride, chemical formula 6), PMD (2,2-pentamethylene-1,3-dioxolane, Chemical Formula 7), BEC (3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate, Chemical Formula 8) and EDTDA (ethylenediaminetetraacetic acid dianhydride, Examples include, but are not limited to, chemical formula 9).

[0024]

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[0025]

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[0026]

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[0027]

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[0028]

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[0029]

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[0030]

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[0031]

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[0032]

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As the solvent 118, commercially available or conventionally used solvents or electrochemical substances (such as liquids (ethers), polymers, gels or plastics) can be used. Preferably, propylene carbonate (PC) or ethylene is used. Organic carbonate solvents such as carbonate (EC).

FIG. 4 is a schematic view of the battery according to the present invention after the initial charge. As shown in FIG. 4, the battery 1 after the initial charge
10 is a passivation layer 12 on the surface 126 of the metal current collector 122.
4 As described in more detail below, passivation layer 124
Is formed by reduction of an additive existing near the interface between the electrolyte 116 and the surface 126 of the metal current collector 122.
As described above, this passivation layer 124 substantially prevents contact between the solvent 118 and the surface 126 and substantially prevents gassing resulting from decomposition of the solvent. Also, as described above, the decomposition of the additive itself does not lead to the generation of a large amount of gas that affects the performance of the battery. Therefore, not only can gas generation be substantially prevented, but also the coulomb efficiency of the battery can be drastically increased as compared to a battery manufactured without using the additive of the present invention. The coulomb efficiency will be described in detail below.

FIG. 5 is a flowchart showing a chemical process according to the present invention. As shown in FIG.
The manufacturing method (see FIGS. 3 and 4) and the actual chemical process that takes place in the battery during the initial charge consists of the following steps.

First, the battery before the initial charging is connected to the first electrode 11.
2. It is manufactured by forming the second electrode 114 and the electrolyte 116. As the first electrode 112, for example, an anode having a metal current collector 122 is exemplified, and as the second electrode 114, a cathode is exemplified. In the form of a secondary battery, the anode and cathode are interchangeable depending on the state of charge or discharge of the battery. Certain electrolytes, as well as electrodes, can be manufactured using conventional techniques. Further, the solvent 118 and the additive 120 may be initially associated with the electrolyte 116. Also, as described above, the additive 120 can be associated with one or both of the first electrode 112 and the second electrode 114.

After fabrication of the battery 110, the battery is initially charged to at least partially form the passivation layer 124. After the initial charge, the additive 120 is applied to the first electrode 112
Is reduced near the interface between the surface 126 of the metal current collector 122 and the electrolyte 116. Such reductions include a change in the chemical structure of the additive, such that the additive is at least substantially insoluble in the electrolyte 116, or the additive is associated with a metal current collector surface.

The passivation layer is composed of the solvent 11 in the electrolyte 116.
8 is substantially prevented from contacting the metal current collector surface. Accordingly, the prevention of the contact substantially prevents the decomposition of the solvent, more specifically, the generation of gas in the battery 110.

Although the decomposition of the solvent and the decomposition of the conventional additive that occur upon contact with the electrode surface cause a substantial loss in Coulomb efficiency, the battery using the additive of the present invention has a higher efficiency than the battery not using the additive. Thus, it can be seen that the first cycle coulomb efficiency, and in some cases, the first to tenth cycle coulomb efficiency are substantially improved.

[0040]

EXAMPLES To demonstrate the improvement in electrochemical performance, batteries were made using various additives as described below. The experimental methods and results are summarized below.

First, a copper current collector (anode), a metal lithium cathode having a metal lithium reference electrode, and an additive (0.5%) in a PC electrolyte containing 1M LiAsF ₆ were used.
~ 5.0 wt%). After battery production, using cyclic voltammetry,
The conversion efficiency from the additive to the passivation layer in the battery was measured. The manufactured battery was subjected to a cycle step from 3.0 V to 0.0 V stepwise. The results of the voltammetry were converted into Coulomb efficiencies, and the Coulomb efficiencies at 1 to 10 cycles are shown in Table 1 below. Coulomb efficiency is 10
A value closer to 0% is more preferable.

[0042]

[Table 1]

As can be seen from Table 1, most of the batteries to which the above additives were added showed better results than the batteries to which no additives were added. Among them, SA, HTP (1%) and BE
The cells to which C was added exhibited extremely favorable Coulomb efficiency values throughout the first to tenth cycles. Furthermore, the cells with added SA exhibited a very high first cycle Coulomb efficiency of 91%.

The above description and drawings are merely illustrative of the invention, and various modifications and changes can be made in the present invention without departing from the gist of the invention.

[0045]

The battery of the present invention substantially prevents gas generation in the battery due to the decomposition of the solvent used in the electrolyte, and also suppresses the additive itself during the charge / discharge cycle and storage of the battery. Since the gas generation due to decomposition is substantially suppressed and the cycle coulomb efficiency is very high, the industrial value of the present invention is high.

[Brief description of the drawings]

FIG. 1 is a schematic view of a conventional battery before initial charging.

FIG. 2 is a schematic view of a conventional battery after initial charging.

FIG. 3 is a schematic diagram of a battery according to the present invention before initial charging.

FIG. 4 is a schematic diagram of a battery according to the present invention after initial charging.

FIG. 5 is a flowchart showing a chemical process according to the present invention.

[Explanation of symbols]

 10: Battery 12: First electrode 14: Second electrode 16: Electrolyte 18: Solvent 20: Conventional additive 20 ': Passivation layer 110: Battery of the present invention 112: First electrode 114: Second electrode 116: Electrolyte 118: Solvent 120: Additive 122: Metal current collector 124: Passivation layer 126: Surface of metal current collector

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Eric S. Kolb, Massachusetts, USA 01720 Acton Tenney C.I.

Claims (16)

[Claims] 1. A method according to claim 1, wherein at least one electrode includes a first electrode and a second electrode each containing a metal current collector having one surface, an electrolyte containing at least one solvent, and at least one metal current collector. A battery comprising: an additive and / or a reducing additive associated with a surface; a passivating means containing the additive or the reducing additive; and a means for substantially preventing gas generation. Substantially prevents contact of at least one solvent in the electrolyte with the surface of the at least one metal current collector, resulting in decomposition of the solvent upon contact with the surface of the at least one metal current collector. The gas generation preventing means is substantially associated with an additive or a reducing additive, and is provided on the surface of the at least one metal current collector during charge / discharge cycles and storage of the battery. A battery having a controlled electrode surface, which is a means for substantially preventing gas generation in the battery due to decomposition of the additive. 2. The battery according to claim 1, wherein the additive or the reducing additive is means for improving the coulomb efficiency of the battery. 3. The battery according to claim 2, wherein the Coulomb efficiency over the first to tenth cycles exceeds 85%. 4. The battery according to claim 2, wherein the coulomb efficiency in the first cycle is 91% or more. 5. The battery according to claim 1, further comprising means for substantially preventing dendrite formation near the surface of the at least one metal current collector. 6. The battery according to claim 5, wherein the dendrite formation preventing means comprises an additive and / or a reducing additive. 7. The battery according to claim 1, wherein the reduction additive is soluble or insoluble in the electrolyte before reduction. 8. The battery according to claim 1, wherein the metal current collector comprises a metal foil having a thickness of less than 25 μm. 9. A step of (a) manufacturing a first electrode and a second electrode including a metal current collector in which at least one electrode has one surface; and (b) at least one solvent for the first and second electrodes. And (c) associating an additive with at least one electrolyte or at least one electrode comprising a metal current collector having one surface. Battery manufacturing method. 10. The additive according to claim 9, wherein the additive is insoluble in the electrolyte.
The method described in. 11. The method according to claim 9, wherein an additive is applied directly to a surface of the at least one metal current collector. 12. A step of (a) manufacturing a first electrode and a second electrode including a metal current collector in which at least one electrode has one surface; and (b) at least one solvent for the first and second electrodes. Associating at least one electrolyte comprising: (c) associating an additive with an electrolyte or a surface of the at least one metal current collector; and (d) associating an additive with the surface of the at least one metal current collector. Forming a passivation layer between the electrolyte and an electrolyte, wherein the passivation layer forming step further comprises: (1) charging a battery; and (2) the metal. A step of substantially reducing the additive on the surface of the current collector to make the reducing additive substantially insoluble in the electrolyte; and (3) at least one solvent in the electrolyte and the surface of the at least one metal current collector. Substantially interacts with And (4) substantially preventing gas generation in the battery due to decomposition of the reducing additive during charge / discharge cycles and storage of the battery. Chemical process. 13. The chemical process of claim 12, wherein said battery exhibits a Coulombic efficiency of greater than 85% during the first to tenth cycles. 14. The chemical process according to claim 12, wherein the battery exhibits a first cycle Coulombic efficiency of 91% or more. 15. The method according to claim 1, wherein the additive is insoluble in the electrolyte.
15. The chemical process according to any one of 2 to 14. 16. The chemical process according to claim 12, wherein an additive is applied directly to a surface of the at least one metal current collector.