KR20170039369A - Electrolyte additives for secondary battery and secondary battery comprising same - Google Patents

Abstract

The present invention relates to an electrolyte additive for a secondary battery and a secondary battery comprising the same. The electrolyte additive for a secondary battery of the present invention can improve output performance of a battery by lowering interfacial resistance of the battery in battery discharge, and can implement stable charge and discharge capacity of the battery even in a high temperature environment.

Description

ELECTROLYTE ADDITIVES FOR SECONDARY BATTERY AND SECONDARY BATTERY COMPRISING SAME BACKGROUND OF THE INVENTION 1. Field of the Invention [0001]

TECHNICAL FIELD The present invention relates to an electrolyte additive for a secondary battery and a secondary battery including the same, and more particularly, to an electrolyte additive for a secondary battery and a secondary battery including the same, which improves the output characteristics and high temperature storage characteristics of the battery.

As the use of secondary batteries has diversified, the market for secondary batteries related to electric vehicles and wireless home appliances has been gradually expanding. The secondary battery has been required to have a high output characteristic in a specific working environment, and efforts have been made to improve the output characteristics of the secondary battery by using electrolytes, in particular, of the battery materials.

In the past, a number of techniques have been reported for adding specific additives to electrolytes for secondary batteries in order to improve output characteristics or life characteristics. For example, Japanese Laid-Open Patent Publication No. 2003-137890 and Korean Laid-Open Patent Application No. 2013-0102969 disclose electrolytes comprising lithium oxalato borate or lithium oxalate phosphate, respectively. Korean Patent No. 1486618 discloses that the cyclic lifetime characteristics of a battery and the output characteristics of a battery at low or high temperature can be improved by incorporating a phenyl sulfonic acid compound into an electrolytic solution and disclosed in Korean Patent Publication No. 2015-0050493 Discloses that ethylene sulfate can be included in an electrolyte to improve the output characteristics of the battery at high temperature and low temperature. Korean Patent Laid-Open Publication No. 2015-0050082 discloses that a compound containing a sulfinyl group can be added to an electrolytic solution to improve the cycle characteristics of the battery. In Korean Patent Laid-Open Publication No. 2013-0008174, a propylene sulfide compound is dissolved in an electrolyte It is described that the life characteristics of the battery can be improved at high temperature by using it as an additive. Korean Patent No. 0976958 discloses that a high temperature stability of a battery can be improved by using a sulfone compound as an electrolyte additive agent, and Japanese Patent No. 4190162 discloses that propene sulfone is used as an electrolyte additive, High temperature stability can be improved, and WO 2005-053644 describes that a sulfuric acid ester compound can be added to an electrolyte to improve the high-temperature storage capacity characteristics of the battery.

However, in the case of an electric vehicle battery, it is still urgent to develop an electrolyte additive for a secondary battery capable of satisfying an output characteristic and a high temperature storage characteristic of a battery capable of sufficiently securing a necessary amount of electric current at the start of a rapid acceleration while shortening a charging time.

As a result of continuous research, the present inventors have found a compound capable of improving the output characteristics and high-temperature storage characteristics of a secondary battery, and applying the same to an electrolyte for a secondary battery, thereby completing the present invention.

Japanese Patent Application Laid-Open No. 2003-137890 Korea Patent Publication No. 2013-0102969 Korean Patent No. 1486618 Korean Patent Publication No. 2015-0050493 Korean Patent Publication No. 2015-0050082 Korea Patent Publication No. 2013-0008174 Korean Patent No. 0976958 Japanese Patent No. 4190162 International Patent Application WO < RTI ID = 0.0 >

Accordingly, an object of the present invention is to provide an electrolyte additive capable of improving the output characteristics and high-temperature storage characteristics of a secondary battery, and an electrolyte and a secondary battery containing the same.

In order to achieve the above object, the present invention provides an electrolyte additive for a secondary battery having a structure represented by the following formula (1) or a structure represented by the following formula (2)

The present invention also relates to a nonaqueous solvent; Lithium salts; And an electrolyte additive having the structure of Formula 1 or the structure of Formula 2.

Further, the present invention provides a secondary battery including the above-described electrolyte for a secondary battery.

The electrolyte additive for a secondary battery of the present invention can improve the output characteristics and high-temperature storage capacity characteristics of the battery.

Hereinafter, the present invention will be described in detail.

The electrolyte additive for a secondary battery according to the present invention is for improving the output characteristics and high temperature storage characteristics of a secondary battery and has a structure represented by the following formula (1) or a structure represented by the following formula (2).

[Chemical Formula 1]

(2)

The electrolyte additive of the present invention is a spiro chemical structure and can be prepared by a conventional method.

The present invention also relates to a nonaqueous solvent; Lithium salts; And an electrolyte additive represented by the structure of the formula (1) or the structure of the formula (2).

The nonaqueous solvent preferably has a high solubility with respect to the lithium salt and the additive. Specific examples thereof include ethylene carbonate, propylene carbonate, ethylmethyl carbonate, dimethyl carbonate, Gamma-butyrolactone, diethyl carbonate and the like can be used alone or in combination. More specifically, linear carbonates such as ethyl methyl carbonate, dimethyl carbonate, and diethyl carbonate, and propylene carbonate , Ethylene carbonate, and the like can be mixed and used.

However, the non-aqueous solvent is preferably dehydrated, and the concentration of water in the non-aqueous solvent may be 150 ppm by weight or less. When the moisture concentration of the non-aqueous solvent exceeds 150 ppm by weight, it is difficult to optimize the performance of the electrolyte due to decomposition of the lithium salt in the battery.

Specifically, LiClO ₄ , LiCF ₃ SO ₃ , LiPF ₆ , LiBF ₄ , LiAsF ₆ , LiN (CF ₃ SO ₂ ) ₂ , and the like can be used singly or in combination as the lithium salt. have.

The concentration (content) of the lithium salt may be 0.9 M to 3.0 M (mol / liter), specifically, 1.0 M to 2.0 M. By including the lithium salt in the above content range, the ion conductivity of the electrolytic solution can be ensured at an appropriate level.

The content of the electrolyte additive having the structure of Formula 1 or the structure of Formula 2 is 0.05 to 20% by weight, 0.05 to 10% by weight, 0.05 to 5% by weight, 0.05 to 3% by weight, 0.05 to 2% by weight 0.5 to 2% by weight, 0.5 to 1.5% by weight, 0.5 to 1.2% by weight, 0.5 to 1% by weight, 1 to 1.5% by weight or 1 to 1.2% by weight. By including the additive in the above content range, it is possible to maintain excellent physical properties in terms of power improvement and chemical storage stability.

The electrolyte for a secondary battery of the present invention is a nonaqueous solvent; Lithium salts; And an electrolyte additive having the structure of Formula 1 or the structure of Formula 2 may be mixed and stirred.

The secondary battery battery of the present invention can be manufactured by injecting the above-described electrolyte for a secondary battery of the present invention into an electrode assembly including a cathode, a cathode and a separator therebetween. The secondary battery of the present invention includes all kinds of secondary batteries, and specifically, it may be a lithium ion battery, a lithium ion polymer battery, or a lithium polymer battery.

The electrolyte additive for a secondary battery of the present invention can improve the output characteristics and high-temperature storage capacity characteristics of the battery.

Hereinafter, the present invention will be described in more detail with reference to specific examples and comparative examples. The following examples are intended to further illustrate the present invention and are not intended to limit the scope of the present invention.

[ Example ]

Example  One.

429 g of ethylene carbonate, 589 g of ethylmethyl carbonate and 380 g of diethyl carbonate were mixed and 167.1 g of LiPF ₆ was added thereto to prepare a 1.1 M LiPF ₆ electrolytic solution. Then, pentaerythritol Pentaerythritol disulfite (Manufacturing Method Reference: British Patent Application 1959-024351) was added in an amount of 0.5% by weight based on the total amount of the electrolytic solution to prepare an electrolytic solution for battery test.

[Chemical Formula 1]

Example  2.

An electrolytic solution for battery test was prepared in the same manner as in Example 1, except that pentaerythritol disulfite was added in an amount of 1.5 wt% based on the total amount of the electrolytic solution.

Example  3.

An electrolytic solution for battery test was prepared in the same manner as in Example 1, except that pentaerythritol disulfite was added in an amount of 3.0 wt% based on the total amount of the electrolytic solution.

Example  4.

An electrolytic solution for battery test was prepared in the same manner as in Example 1, except that pentaerythritol disulfite was added in an amount of 10.0% by weight based on the total amount of the electrolytic solution.

Example  5.

An electrolytic solution for battery test was prepared in the same manner as in Example 1, except that pentaerythritol disulfite was added in an amount of 15.0 wt% based on the total amount of the electrolytic solution.

Example  6.

Except that pentaerythritol disulfate (Preparation Method: British Patent Application 1959-024351) represented by the following formula (2) was added instead of pentaerythritol disulfite to prepare an electrolytic solution for battery test in the same manner as in Example 1 .

(2)

Example  7.

An electrolytic solution for battery test was prepared in the same manner as in Example 6, except that pentaerythritol disulfate was added in an amount of 1.5% by weight based on the total amount of the electrolytic solution.

Example  8.

An electrolytic solution for battery test was prepared in the same manner as in Example 6, except that pentaerythritol disulfate was added in an amount of 3.0 wt% based on the total amount of the electrolytic solution.

Example  9.

An electrolytic solution for battery test was prepared in the same manner as in Example 6, except that pentaerythritol disulfate was added in an amount of 10.0% by weight based on the total amount of the electrolytic solution.

Example  10.

An electrolytic solution for battery test was prepared in the same manner as in Example 6, except that pentaerythritol disulfate was added in an amount of 15.0 wt% based on the total amount of the electrolytic solution.

Comparative Example  One.

An electrolytic solution for battery test was prepared in the same manner as in Example 1, except that pentaerythritol disulfite was not added.

Comparative Example  2.

Except that 1,3-trimethylene sultone instead of pentaerythritol disulfite was added in an amount of 3% by weight based on the total amount of the electrolytic solution, an electrolytic solution for battery test was prepared in the same manner as in Example 1 .

Comparative Example  3.

(Carboxymethyl) disulfide) instead of pentaerythritol disulfite was added in an amount of 3% by weight based on the total amount of the electrolytic solution, an electrolytic solution for battery test was prepared in the same manner as in Example 1 Respectively.

Comparative Example  4.

An electrolytic solution for a battery test was prepared in the same manner as in Example 1, except that ethylene sulfite was added in an amount of 3 wt% based on the total amount of the electrolytic solution instead of pentaerythritol sulfite.

Experimental Example  1. Impedance Measurement of Secondary Battery

A 1.3Ah pouch battery was fabricated by a conventional method using a cathode material obtained by mixing LiNi ₅ Co ₂ Mn ₃ and LiMnO ₂ as cathode active materials in a ratio of 1: 1 (weight ratio) and an anode material using artificial graphite as a negative electrode active material, 6 g of each of the electrolyte solutions for testing batteries of Examples 1 to 10 and Comparative Examples 1 to 4 was injected to complete the secondary battery. Thereafter, the impedance obtained when discharging at 3 C (coulomb) for 10 seconds while maintaining a 60% charged state voltage of the 1.3 Ah pouch battery at 25 ° C. was measured with a PNE-0505 charge / discharge device (manufacturer: Note) PNE solution) and the results are shown in Table 1 below.

Further, after measuring the impedance of the battery, the discharge impedances of the batteries were measured in the same manner as described above after storage for 7 days and 14 days in a 70 ° C oven.

Impedance (mΩ) 25 ℃ 7 days after storage at 70 ℃ 14 days after storage at 70 ℃ Example 1 33 40 47 Example 2 35 37 40 Example 3 39 40 41 Example 4 42 41 43 Example 5 43 44 47 Example 6 35 42 49 Example 7 37 39 41 Example 8 41 42 43 Example 9 43 42 44 Example 10 44 45 48 Comparative Example 1 35 56 81 Comparative Example 2 35 50 74 Comparative Example 3 47 56 96 Comparative Example 4 35 51 70

As shown in Table 1, Examples 1 to 10 including the additive of the present invention show that the impedance at the time of high temperature storage and discharge is lower than that of Comparative Examples 1 to 4. This shows that the output characteristics of the battery are improved due to the low resistance characteristic between the electrode and the electrolyte in the battery discharge process by including the additive of the present invention.

Experimental Example  2. High-temperature storage characteristics of secondary battery (capacity Recoverability ) evaluation

A secondary battery (1.3Ah pouch battery) which had been subjected to the cellization process in the same manner as in Experimental Example 1 was stored in a 70 ° C oven for 7 days and 14 days in a fully charged state, The capacity was measured with a PNE-0505 charge / discharge device, and the discharge capacity after a high-temperature storage relative to the initial charge capacity of the battery was shown in Table 2 as a percentage of the initial capacity as a recovery capacity.

High Temperature Storage Recovery Capacity (%) Early (%) 7 days after storage at 70 ℃ 14 days after storage at 70 ℃ Example 1 100 90 80 Example 2 100 93 82 Example 3 100 94 90 Example 4 100 92 84 Example 5 100 90 83 Example 6 100 90 80 Example 7 100 93 82 Example 8 100 94 90 Example 9 100 92 84 Example 10 100 90 83 Comparative Example 1 100 85 74 Comparative Example 2 100 85 75 Comparative Example 3 100 84 67 Comparative Example 4 100 86 79

As shown in Table 2, as compared with Comparative Examples 1 to 4, Examples 1 to 10, which are electrolytic solutions containing the additive of the present invention, confirm that the recovery capacity after storage at 70 ° C relative to the initial temperature is stable . This shows that the reduction of the electrochemical electrode capacity occurring during high-temperature storage of the battery is remarkably reduced by including the additive of the present invention. As a result, it is confirmed that the use of the additive of the present invention realizes a stable charge / discharge capacity even at a high temperature.

Claims (4)

An electrolyte additive for a secondary battery having a structure represented by the following formula (1) or a structure represented by the following formula (2)
[Chemical Formula 1]

(2)

Non-aqueous solvent;
Lithium salts; And
An electrolyte solution for a secondary battery comprising an electrolyte solution additive having a structure represented by the following formula (1) or a structure represented by the following formula (2)
[Chemical Formula 1]

(2)

3. The method of claim 2,
Wherein the electrolyte additive is contained in an amount of 0.05 to 20% by weight based on the total amount of the electrolyte for the secondary battery.
A secondary battery comprising an electrolyte solution for a secondary battery according to claim 2 or 3.