KR101720413B1 - Additive for electrochemical device and electrolyte, electrode and electrochemical device comprising the same - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to additives, electrolytic solutions, electrodes and electrochemical devices for electrochemical devices comprising phosphorous or boron-containing compounds having a double bond.

Description

TECHNICAL FIELD [0001] The present invention relates to an additive for electrochemical devices, and an electrolyte, an electrode, and an electrochemical device including the additive,

The present application claims the benefit of Korean Patent Application No. 10-2014-0055866, filed on May 9, 2014, to the Korean Intellectual Property Office, the entire contents of which are incorporated herein by reference.

The present specification relates to additives for electrochemical devices. The present invention also relates to an electrolyte and an electrode including an additive for electrochemical devices. The present invention also relates to an electrochemical device including an additive for electrochemical devices.

2. Description of the Related Art [0002] In recent years, portable electronic devices have been widespread, and as portable electronic devices have rapidly become smaller, lighter, and thinner, secondary batteries that are small, lightweight and capable of long- Development is required.

Lithium secondary batteries are widely used as driving power sources for portable electronic devices because of their high energy density due to their low oxidation-reduction potential and molecular weight. Therefore, in the lithium secondary battery, maintaining the cycle capacity and securing the high-temperature stability characteristics in accordance with the increase of the capacity and the voltage is one of the characteristics required to enhance the performance of the battery. Development of a variety of materials has been required for various performance improvements such as capacity, life span, and high temperature characteristics of such lithium secondary batteries.

Journal of Power Sources 144 (2005) 170-175

The present invention provides an additive for an electrochemical device, an electrolyte solution containing the additive, an electrode, and an electrochemical device.

An embodiment of the present invention provides an additive for an electrochemical device comprising a phosphorus-containing or boron-containing compound having a double bond.

According to one embodiment of the present disclosure, the phosphorus or boron-containing compound having a double bond includes phosphorus or boron as a ring source, an aliphatic or aromatic ring having 2 oxygen atoms and 2 to 5 carbon atoms.

According to one embodiment of the present invention, the phosphorus or boron-containing compound having a double bond further includes one or two or more aliphatic or aromatic rings having 5 to 10 carbon atoms condensed in the aliphatic or aromatic ring.

In addition, one embodiment of the present invention provides an electrolyte solution containing the additive for electrochemical device.

In addition, one embodiment of the present invention provides an electrode comprising an additive for the electrochemical device and a phosphor or boron-containing compound having the double bond in a part or all of the surface formed by an electrochemical polymer reaction.

Also, one embodiment of the present invention is an electrochemical device comprising a cathode, a cathode, a separator, and an electrolyte, wherein the electrolyte contains an additive for the electrochemical device, and / or at least one of the anode and the cathode has a An additive for an electrochemical device, and a phosphor or boron-containing compound having the double bond are contained in part or all of the surface of the film formed by the electrochemical polymer reaction.

The additive for an electrochemical device according to one embodiment of the present invention adsorbs at a defect point or an activation point on the surface of the secondary battery anode to inhibit the oxidative decomposition reaction of the nonaqueous electrolyte or form a complex with the metal ion eluted from the anode, It is possible to suppress the electrodeposition of metal ions to the negative electrode.

According to one embodiment of the present invention, the additive for electrochemical devices forms an effective protective film of the positive electrode by a polymer reaction to prevent further decomposition of the electrolyte, protects the positive electrode against attack of the lithium salt decomposition product, , Output, and / or high temperature characteristics.

Hereinafter, the present invention will be described in more detail.

One embodiment of the present disclosure provides an additive for an electrochemical device comprising a phosphorus or boron-containing compound having a double bond.

According to one embodiment of the present disclosure, the phosphorus or boron-containing compound having a double bond includes phosphorus or boron as a ring source, an aliphatic or aromatic ring having 2 oxygen atoms and 2 to 5 carbon atoms.

According to one embodiment of the present invention, the phosphorus or boron-containing compound having a double bond further includes one or two or more aliphatic or aromatic rings having 5 to 10 carbon atoms condensed in the aliphatic or aromatic ring.

According to one embodiment of the present invention, the phosphorus or boron-containing compound having a double bond has a halogen group or an alkenyl group having 1 to 5 carbon atoms which is substituted or unsubstituted with an alkyl group having 1 to 10 carbon atoms.

According to one embodiment of the present invention, the phosphorus or boron-containing compound having a double bond has an alkenyl group having 1 to 5 carbon atoms.

The additive for the electrochemical device may be added to the electrolytic solution, or a phosphorus or boron-containing compound having the double bond may be formed on a part or surface of the surface of the electrode by a film formed by an electrochemical polymer reaction. The membrane provided on a part or the surface of the electrode can be formed on part or all of the surface of the electrode by adding the additive for electrochemical element to the electrolytic solution during the production of the battery, Or the like.

According to one embodiment of the present invention, the phosphorus- or boron-containing compound having a double bond is represented by the following formula (1).

[Chemical Formula 1]

In Formula 1,

X is P or B,

Y is an organic group containing a double bond,

n is an integer of 1 to 3,

m is 0 or 1 when X is P, 0 when X is B,

R1 to R4 each independently represent hydrogen; A halogen group; Or a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms,

Two adjacent substituents of R 1 to R 4 are bonded to each other to form a substituted or unsubstituted C2-C20 heterocycle; Or a substituted or unsubstituted aromatic ring having 6 to 20 carbon atoms.

According to one embodiment of the present invention, the phosphorus or boron-containing compound having a double bond may be a compound represented by any one of the following formulas (1-1) to (1-3).

[Formula 1-1]

 [Formula 1-2]

[Formula 1-3]

Wherein X, Y, and m are as defined in Chemical Formula 1,

R1 to R8 each independently represent hydrogen; A halogen group; Or a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms,

Two adjacent substituents of R 1 to R 8 may be bonded to each other to form a substituted or unsubstituted C2-C20 heterocycle; Or a substituted or unsubstituted aromatic ring having 6 to 20 carbon atoms.

According to one embodiment of the present invention, the phosphorus or boron-containing compound having a double bond may be a compound represented by any one of the following formulas (1-4) to (1-7).

 [Formula 1-4]

[Formula 1-5]

[Chemical Formula 1-6]

[Chemical Formula 1-7]

In Formulas 1-4 to 1-7, X, Y, and m are as defined in Formula 1,

R1 to R8 each independently represent hydrogen; A halogen group; Or a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms,

Two adjacent substituents of R 1 to R 8 may be bonded to each other to form a substituted or unsubstituted C2-C20 heterocycle; Or a substituted or unsubstituted aromatic ring having 6 to 20 carbon atoms.

In the present specification, examples of the "halogen group" include fluorine, chlorine, bromine or iodine.

According to one embodiment of the present invention, R 1 to R 4 in Formula 1-1 are hydrogen.

According to one embodiment of the present invention, R 1 to R 6 in Formula 1-2 are hydrogen.

According to one embodiment of the present invention, R 1 to R 8 in the general formula 1-3 are hydrogen.

According to one embodiment of the present invention, R1 to R8 in the general formula 1-4 are hydrogen.

According to one embodiment of the present invention, R 1 to R 4 in Formula 1-5 are hydrogen.

According to one embodiment of the present invention, R 1 to R 6 in the formula 1-6 are hydrogen.

According to one embodiment of the present invention, R 1 to R 8 in the general formula 1-7 are hydrogen.

According to one embodiment of the present invention, X is P in the above formulas 1-1 to 1-7.

According to one embodiment of the present invention, X is B in the above formulas 1-1 to 1-7.

According to one embodiment of the present invention, in the general formulas 1-1 to 1-7, Y is an alkenyl group having 1 to 5 carbon atoms which is substituted or unsubstituted with a halogen group or an alkyl group having 1 to 10 carbon atoms.

According to one embodiment of the present invention, in the above formulas 1-1 to 1-7, Y is an alkenyl group having 1 to 5 carbon atoms.

According to one embodiment of the present invention, in Formulas 1-1 to 1-7, Y is an alkenyl group having 2 to 4 carbon atoms.

According to one embodiment of the present invention, in the above formulas 1-1 to 1-7, Y is propenyl.

According to one embodiment of the present disclosure, the phosphorus or boron-containing compound having a double bond is a compound represented by any one of the following structural formulas.

[Formula 2-1]

[Formula 2-2]

[Formula 2-3]

[Chemical Formula 2-4]

[Chemical Formula 2-5]

[Chemical Formula 2-6]

[Chemical Formula 2-7]

[Chemical Formula 2-8]

[Chemical Formula 2-9]

[Chemical Formula 2-10]

[Chemical Formula 2-11]

[Formula 2-12]

Phosphorus or boron-containing compounds having double bonds according to the above-described embodiments may form cation radicals when the double bond is electrically oxidized to cause a polymer reaction to form a film or film. At this time, if P or B is included, the formed film or film has a porous structure, which can reduce the resistance of the electrode film.

The phosphorus or boron-containing compound having a double bond may include an aromatic ring group or an aliphatic ring group. They affect the solubility and oxidation potential of the compound in the electrolytic solution and can be selected depending on the solvent composition of the electrolytic solution.

According to one embodiment of the present invention, the electrolytic solution may further include an electrolyte salt and an electrolyte solvent.

According to one embodiment of the present disclosure, the electrolyte salt comprises lithium cations and is selected from the group consisting of PF ₆ ^- , BF ₄ ^- , Cl _- , Br ^- , I ^- , ClO ₄ ^- , AsF ₆ ^- , SO ₃ CF ₃ ^- , N (SO ₂ CF ₃ ) ₂ ^- , N (SO ₂ F) ₂ ^- , or an ion comprising a combination of at least one of the foregoing.

According to one embodiment of the present invention, the electrolyte solvent may be organic solvents. Specifically, cyclic carbonates, linear carbonates, cyclic esters, linear esters, and combinations thereof may be used. More specifically, examples of the electrolyte solvent include propylene carbonate (PC), ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), dipropyl carbonate ), Dimethyl sulfoxide, acetonitrile, dimethoxyethane, diethoxyethane, tetrahydrofuran (THF), N-methyl-2-pyrrolidone (NMP), gamma butyrolactone (GBL), fluoroethylene carbonate FEC), methyl formate, ethyl formate, propyl formate, methyl acetate, ethyl acetate, propyl acetate, butyl acetate and the like can be used. The organic solvents may be used alone or in combination of two or more. In the case of mixing two or more of them, the mixing ratio can be appropriately adjusted according to the desired lithium secondary electron affinity, which can be widely understood by those skilled in the art. A halogen derivative of the organic solvent may also be used.

According to one embodiment of the present invention, the electrolytic solution may be a non-aqueous electrolytic solution.

According to one embodiment of the present invention, the electrolytic solution may be for an electrochemical device. Specifically, the electrolyte solution may be for a lithium secondary battery.

According to one embodiment of the present invention, the phosphorus or boron-containing compound having a double bond may be contained in an amount of 0.01 wt% or more and 20 wt% or less with respect to the total amount of the electrolytic solution.

If the amount of the phosphorus-containing or boron-containing compound having a double bond is less than 0.01% by weight based on the total amount of the electrolytic solution, the effect of maintaining the desired life may be insufficient. If the amount exceeds 20% by weight, The performance of the device may deteriorate. Therefore, when the phosphorus or boron-containing compound having a double bond is included in the electrolyte solution within the above-mentioned content range, the electrolyte solution can improve the performance of the electrochemical device.

One embodiment of the present invention provides an electrode comprising a phosphor or boron-containing compound having a double bond described above on a part or all of a surface of the film formed by an electrochemical polymer reaction.

According to one embodiment of the present disclosure, the electrode may be an anode, a cathode, or an anode and a cathode. Specifically, the electrode may be an anode.

One embodiment of the present invention relates to a secondary battery including a cathode, a cathode, a separator, and an electrolyte, wherein the electrolyte includes the above-described additive for electrochemical devices.

According to one embodiment of the present invention, at least one of the positive electrode and the negative electrode is an electrode including a phosphor or boron-containing compound having a double bond as described above in a part or all of the surface formed by an electrochemical polymer reaction.

One embodiment of the present invention relates to an electrochemical device including a cathode, a cathode, a separator, and an electrolyte, wherein at least one of the anode and the cathode includes the additive for the electrochemical device and the phosphorus or boron-containing compound And an electrode provided with a film formed by the electrochemical polymer reaction on a part or the whole of the surface.

According to one embodiment of the present invention, the anode includes a cathode active material containing a transition metal, and the phosphorus or boron-containing compound having the double bond in a part or the whole of the anode surface is formed by an electrochemical polymer reaction do.

According to an embodiment of the present invention, the electrochemical device may be a secondary battery, for example, a lithium secondary battery.

According to one embodiment of the present invention, the negative electrode is manufactured by mixing and stirring a negative electrode active material, a binder, a solvent, a conductive material, and / or a dispersant, which is produced by a general method, .

According to one embodiment of the present invention, the negative electrode active material may be a conventional negative electrode active material that can be used for a negative electrode of a conventional secondary battery. Non-limiting examples of the negative electrode active material include lithium metal or a lithium metal alloy, coke, activated carbon, graphite, graphitized carbon, carbon nanotube, graphine, and / Carbon materials, or the like. As the negative electrode current collector, a foil made of a combination of copper, nickel or the like and an alloy thereof may be used.

According to one embodiment of the present invention, the anode may be manufactured in such a manner that the cathode active material is applied on the cathode current collector according to a general method. LiCoO ₂ , LiNiO ₂ , LiMnO ₂ , LiMn ₂ O ₄ , and Li (Ni _a Co _b Mn _c ) may be used as the positive electrode active material. O ₂ , where a, b and c are each a number from 0 to 1, a + b + c = 1, LiFePO ₄ or a mixture of one or more thereof. The positive electrode current collector may be a foil or the like made of a combination of aluminum, nickel, and one or more of these alloys.

According to one embodiment of the present invention, the separation membrane is not particularly limited and may be in the form of a porous membrane. Specifically, the separation membrane may be formed of polyethylene, polypropylene, other polyolefin-based membranes, or multilayer films thereof. Or a ceramic coating may be applied to the separation membrane.

The secondary battery according to one embodiment of the present invention may be manufactured by a conventional method known in the art and may be manufactured by injecting an electrolyte into a cylindrical, square, or pouch-like shape assembled with the cathode, anode, have.

As described above, in the secondary battery according to one embodiment of the present invention, the phosphorus or boron-containing compound having the double bond contained in the electrolytic solution functions as an electrode, particularly on the surface of the anode, The effect of minimizing the reduction can be obtained.

Hereinafter, the present invention will be described in detail by way of examples with reference to the drawings. However, the embodiments according to the present disclosure can be modified in various other forms, and the scope of the present specification is not construed as being limited to the embodiments described below. Embodiments of the present disclosure are provided to more fully describe the present disclosure to those of ordinary skill in the art.

[ Example  1 to 6]

An electrolyte solution was prepared by adding 1 wt% of the compound shown in Table 1 to a 1: 2 volume ratio solution of 1M LiPF ₆ in ethylene carbonate and ethyl methyl carbonate.

N-methyl-2-pyrrolidone (NMP) was added to 90% by weight of graphite carbon and 10% by weight of polyvinylidene difluoride (PVDF) as a negative electrode and mixed in a mixer for 2 hours. And dried. The positive electrode was prepared by mixing 90 wt% of LiCoO ₂ , 3 wt% of PVDF, and 7 wt% of carbon black as an NMP slurry for 2 hours, coating on an aluminum foil, and drying at 150 ° C. A polyolefin-based separator was interposed between the anode and the cathode, and the electrolyte was injected into the cylindrical secondary battery.

[ Comparative Example  1 to 5]

The same procedures as in Examples were carried out except that the compounds shown in Table 1 were used as additives.

additive Discharge Capacity Retention Rate (%)
23 ℃ Discharge Capacity Retention Rate (%)
45 ° C Example 1

85 80 Example 2

86 83 Example 3

85 82 Example 4

86 84 Example 5

83 82 Example 6

84 82 Comparative Example 1

67 59 Comparative Example 2

73 70 Comparative Example 3

69 61 Comparative Example 4

72 70 Comparative Example 5

70 64

[Experimental Example] - Performance evaluation of lithium secondary battery

Each of the secondary batteries prepared in Examples 1 to 6 and Comparative Examples 1 to 5 was subjected to the following tests. Each battery was repeatedly charged and discharged at a temperature of 23 ° C and 45 ° C in a range of 4.4 V and 3 V at a current of 1.0 C to measure a change in the discharge capacity of the battery. To confirm the anode protection effect, the battery was charged to a high voltage of 4.4 V instead of 4.2 V, and discharged at a relatively fast C-rate of 1.0 C instead of 0.5 C. The discharge capacity retention after 200 cycles of the initial discharge capacity is shown in Table 1 below.

As shown in Table 1, the discharge capacity retention ratio in Examples was superior to that of Comparative Examples. Thus, it was confirmed that the additives according to the embodiments of the present invention can improve the capacity maintenance of the electrochemical device.

Claims (18)

An additive for an electrochemical device comprising a phosphorus-containing or boron-containing compound having a double bond represented by the following general formula (1-5) or (1-7).
[Formula 1-5]

[Chemical Formula 1-7]

In Formula 1-5, X is P,
In Formula 1-7, X is P or B,
In Formulas 1-5 and 1-7,
Y is a C ₂ -C ₄ alkenyl group,
m is 0,
R ₁ to R ₈ are hydrogen. delete delete delete delete delete delete The additive for an electrochemical device according to claim 1, wherein the phosphorus- or boron-containing compound having a double bond is represented by any one of the following formulas:

An electrolyte solution comprising the additive for an electrochemical device according to any one of claims 1 to 8. The electrolyte according to claim 9, wherein the electrolyte further comprises an electrolyte salt and an electrolyte solvent. The electrolytic solution according to claim 9, wherein the phosphorus or boron-containing compound having a double bond is contained in an amount of 0.01 wt% to 20 wt% with respect to the total amount of the electrolytic solution. The electrolyte according to claim 9, wherein the electrolyte is a non-aqueous liquid electrolyte. The electrolyte according to claim 9, wherein the electrolyte is a secondary battery. An electrode comprising an additive for an electrochemical device according to any one of claims 1 to 8 and a film formed by an electrochemical polymer reaction of a phosphorus or boron-containing compound having a double bond on a part or the whole of its surface. 15. The electrode of claim 14, wherein the electrode is an anode, a cathode, or an anode and a cathode. A secondary battery comprising an anode, a cathode, a separator, and an electrolyte according to claim 9. [Claim 16] The method according to claim 16, wherein at least one of the positive electrode and the negative electrode includes a phosphor or boron-containing compound having a double bond and a phosphorus or boron-containing compound having the double bond in a part or all of the surface formed by the electrochemical polymer reaction A secondary battery. Wherein at least one of the positive electrode and the negative electrode is an electrode according to claim 14, the positive electrode, the negative electrode, the separator, and the electrolyte.