KR20160143109A - Electrode for secondary battery and Method for manufacturing the same - Google Patents

Abstract

The present invention relates to an electrode for a secondary battery including an electrode current collector and an electrode active material layer formed on at least one side of the electrode current collector and a method for manufacturing the same. The electrode active material layer has a plurality dot patterns which are separated from each other in parallel, thereby improving battery performance by increasing the capacity of the electrode per initial charging/discharging gram, discharge capacity, and constant current charging time.

Description

TECHNICAL FIELD [0001] The present invention relates to an electrode for a secondary battery,

The present invention relates to an electrode for a secondary battery and a manufacturing method thereof, and more particularly, to an electrode for a secondary battery having improved impregnation properties for an electrolyte and a method for manufacturing the same.

2. Description of the Related Art [0002] In recent years, demand for secondary batteries which can be recharged by the spread of portable electronic devices such as mobile phones, notebooks, and PDAs has been rapidly increasing, and the performance of the secondary batteries has been gradually improved.

Nickel-hydrogen (Ni-MH) batteries and lithium ion (Li-ion) batteries are used as typical secondary batteries. Further, the secondary battery can be divided into a cylindrical shape, a square shape, and a pouch type battery according to the appearance of the case housing the electrode assembly.

The secondary battery is assembled by alternately stacking the positive electrode, the negative electrode, and the separator, inserting the battery into a battery case such as a can or a pouch having a predetermined size and shape, and finally injecting the electrolyte.

At this time, the electrolyte injected later is impregnated into the space between the anode, the cathode and the separator by a capillary force, and this electrolyte plays a role as an agent for the movement of ions. If the impregnation of the electrolyte solution is not performed well, the performance of the produced secondary battery can not be sufficiently exhibited.

However, in the process of producing the secondary battery, it takes a considerable time to impregnate the electrode and the separator with the electrolyte after injecting the electrolyte, and a demanding process condition is required.

Efforts to improve the energy storage capability of secondary batteries are now being demanded. Particularly, although a high loading technique for increasing the amount of active material is applied as well as an effort to change the composition of the active material, battery performance has not been developed due to impregnation property of the electrolyte during high load application.

KR 2013-0004807 A KR 2006-0055380 A

In order to solve the problems of the prior art, it is an object of the present invention to provide an electrode for a secondary battery and a method of manufacturing the same, which can improve the impregnation property of the electrolyte to improve the performance of the battery.

It is to be understood, however, that the technical subject matter of the present invention is not limited to the above-mentioned problems, and other matters not mentioned can be clearly understood by those skilled in the art from the description of the invention described below.

According to an aspect of the present invention, there is provided an electrode for a secondary battery including an electrode current collector and an electrode active material layer formed on at least one surface of the electrode current collector, wherein the electrode active material layer has a plurality The electrode for a secondary battery is provided.

(A) preparing an electrode current collector; (b) forming an electrode active material layer on at least one of both surfaces of the electrode current collector; And (c) irradiating a surface of the electrode active material layer with a laser to form a plurality of dot patterns spaced apart from each other and formed in parallel to each other.

INDUSTRIAL APPLICABILITY According to the present invention, the electrolyte impregnability of the electrode for the secondary battery is improved, thereby improving the efficiency of the manufacturing process of the secondary battery and improving the performance of the secondary battery.

According to the present invention, by forming an intaglio dot pattern on the electrode active material layer of an electrode for a secondary battery, it is possible to improve the battery performance by increasing the capacity per initial charge / discharge g of the electrode, increasing the discharge capacity, and increasing the constant current charge time.

1 is an optical image of a dot pattern produced according to Example 1. Fig.
Fig. 2 is an optical image of a dot pattern produced according to Comparative Example 1. Fig.
3 is an optical image of a dot pattern prepared according to Comparative Example 2. Fig.
Fig. 4 is a profile of a dot pattern produced according to Example 1. Fig.
5 is a profile of a dot pattern prepared according to Comparative Example 1. Fig.
Fig. 6 is a profile of a dot pattern produced according to Comparative Example 2. Fig.
7 is a graph showing a change in capacity per g charge and discharge g per cycle of a battery having a dot pattern prepared according to Reference Example 1, Comparative Example 1, and Comparative Example 2;
FIG. 8 is a graph showing a change in capacitance with a change in discharge current of a battery having a dot pattern manufactured according to Reference Example 1, Comparative Example 1, and Comparative Example 2. FIG.
9 is a graph showing a constant current (CC) charging time of a battery having a dot pattern manufactured according to Reference Example 1, Comparative Example 1, and Comparative Example 2. FIG.

Hereinafter, the present invention will be described in detail.

The electrode for a secondary battery according to the present invention includes an electrode current collector and an electrode active material layer formed on at least one of both surfaces of the electrode current collector.

The electrode for a secondary battery of the present invention may have an electrode active material layer formed on only one surface of the electrode current collector or an electrode active material layer formed on both surfaces of the electrode current collector.

The electrode current collector may be formed of a different metal material depending on whether the electrode is an anode or a cathode. For example, an aluminum material may be used when the electrode is an anode, and a copper material may be used when the electrode is a cathode.

However, the material of the electrode current collector is not limited to the material of the electrode current collector of the present invention, and is not particularly limited as long as it has high conductivity without causing chemical change in the secondary battery .

In addition, the electrode current collector can be used in various forms such as a film, a sheet, a foil, a net, a porous body, a foam, a non-woven fabric, or the like in order to increase the adhesive force with the electrode active material layer by forming fine irregularities on the surface.

When the electrode active material layer is a positive electrode active material layer, for example, LiCoO ₂ , LiMn ₂ O ₄ , LiNiO ₂ , LiMnO ₂ And the like. In the case of the negative electrode active material layer, for example, a carbon-based material, Si, Sn, tin oxide, composite tin alloys, transition metal oxide Etc. may be used.

The electrode active material layer included in the electrode for a secondary battery according to the present invention is characterized in that it has a plurality of dot patterns formed to be spaced apart from each other in order to improve impregnability with the electrolyte solution.

The plurality of dot patterns preferably have an interval of 400 to 800 mu m. When the distance between the dot patterns is less than 400 탆, the energy density of the electrode active material is increased and the energy density is decreased. When the distance is more than 800 탆, it is difficult to expect the impregnation improving effect due to the formation of the engraved pattern.

The diameter of the dots in the dot pattern is preferably 50 to 120 mu m. When the diameter of the dot is less than 50 탆, it is difficult to expect the improvement effect of the impregnation according to the pattern formation. If the diameter exceeds 120 탆, the quantitative loss of the active material is large and the energy density is lowered.

The dot pattern is formed in the electrode active material layer at a recessed angle. The dot pattern preferably has a depth of 5% to 40% of the thickness of the electrode active material layer. When the depth of the dot pattern is less than 5% of the thickness of the electrode active material layer, it is difficult to expect the effect of improving the impregnation property of the electrolyte due to the formation of the dot pattern. If the depth exceeds 40%, the quantitative loss of the electrode active material becomes too large Which can lead to a serious degradation of the energy density.

The dot pattern may be formed by preparing an electrode collector required according to the characteristics of the secondary battery, forming an electrode active material layer on one or both surfaces thereof, and then performing a laser patterning operation on the surface of the electrode active material layer .

In a preferred embodiment of the present invention, the dot pattern may be formed using a pulse laser whose pulse repetition rate can be adjusted. Of the scanner

The laser irradiation interval can be adjusted by changing the speed and pulse repetition rate.

If the size of the laser beam is smaller than the laser irradiation interval, a dot-shaped pattern can be formed and the interval of the dot pattern can be adjusted. The diameter of the dots can be controlled through the size of the laser beam.

The electrode may correspond to a positive electrode or a negative electrode. When an electrode having an engraved pattern formed on an electrode active material layer is improved in electrolyte impregnability, when an anode and a cathode are formed using such an electrode, a separator is interposed therebetween, and a casing is used to manufacture a secondary battery, The efficiency of the manufacturing process can be improved and the performance of the secondary battery can be improved.

According to another aspect of the present invention, there is provided a secondary battery in which the electrode for a secondary battery according to the present invention is applied as at least one of an anode and a cathode.

According to another aspect of the present invention, there is provided a method of manufacturing an electrode assembly, comprising: (a) preparing an electrode current collector; (b) forming an electrode active material layer on at least one of both surfaces of the electrode current collector; And (c) irradiating a surface of the electrode active material layer with a laser to form a plurality of dot patterns spaced apart from each other and formed in parallel to each other.

In the step (c), the plurality of dot patterns may have an interval of 400 to 800 μm.

Hereinafter, the present invention will be described in detail with reference to examples.

≪ Example 1 >

Coin cell (Coin-cell)

A graphite series negative electrode active material was used and the conductive material (Denka black), the thickener (CMC) and the binder (SBR) were mixed in distilled water (H ₂ O) at a weight ratio of 97.5: 0.5: 1.0: And then coated with a copper foil having a thickness of 20 탆 and rolled and dried to prepare a negative electrode. Then, a pulse laser was irradiated to form a dot pattern having a pattern interval of 500 탆, a diameter of 80 탆 and a pattern depth of 15 탆 on the negative electrode active material layer To prepare a negative electrode for a coin cell.

Coin cell (Coin-cell) battery

An electrode assembly was prepared between the lithium metal and the negative electrode prepared above through a separator, and the electrode assembly was embedded in the battery case.

A lithium nonaqueous electrolyte solution containing 1 M of LiPF ₆ as a lithium salt was mixed with ethyl carbonate and ethylmethyl carbonate at a volume ratio of 1: 2, and the mixture was sealed to form a coin-cell. A battery was prepared.

≪ Comparative Example 1 &

A battery was prepared in the same manner as in Example 1, except that the pattern interval was 300 mu m.

≪ Comparative Example 2 &

A battery was prepared in the same manner as in Example 1 except that the pattern interval was changed to 1000 mu m.

<Reference>

A battery was produced in the same manner as in Example 1 without laser patterning.

<Experimental Example 1>

The amount of loading of the electrode active material in the cells prepared in Example 1 and Comparative Examples 1 and 2 was measured, and the amount of decrease in the loading amount of the electrode active material relative to the reference is shown in Table 1 below.

Example 1 Comparative Example 1 Comparative Example 2 reference 0.458 0.453 0.461 0.468 -2.14% -3.21% -1.50% -

As shown in Table 1, it can be seen that as the pattern interval increases, the amount of reduction of the active material becomes smaller.

<Experimental Example 2>

Example 1, Comparative Examples 1 and 2 proceed with the initial charge and discharge test over the 1 ^st cycle (0.1C / 0.1C) and 2 ^nd cycles (0.1C / 0.1C) for the batteries prepared by the results in Are shown in Table 2 below. The same test was performed on the reference.

1 ^st cycle (0.1 C / 0.1 C) 2 ^nd cycle (0.1 C / 0.1 C) charge
(mAh / g) Discharge
(mAh / g) efficiency
(%) charge
(mAh / g) Discharge
(mAh / g) efficiency
(%) reference 373.4 349.3 93.6 352.5 349.5 99.1 Example 1 387.7 361.5 93.3 365.3 361.8 99.0 Comparative Example 1 383.3 360.5 94.1 363.7 360.7 99.2 Comparative Example 2 387.5 361.1 93.2 364.8 361.9 99.2

As shown in Table 2, the batteries of Example 1 and Comparative Examples 1 and 2 including the electrode active material layer having the dithessed dot pattern were increased in initial charge and discharge capacity as compared with the reference.

<Experimental Example 3>

The batteries manufactured in Example 1 and Comparative Examples 1 and 2 were subjected to a discharge test by current, and the results are shown in Table 3 below. The same test was performed on the reference.

0.1 C
Discharge capacity
(mAh / g) 1.0C discharge 2.0C discharge Capacity (mAh / g) 1.0C / 0.1C (%) Capacity (mAh / g) 2.0C / 0.1C (%) reference 349.5 335.8 96.1 223.8 64.0 Example 1 361.8 354.3 97.9 292.9 81.0 Comparative Example 1 360.7 354.1 98.2 291.8 80.9 Comparative Example 2 361.9 357.2 98.7 294.9 81.5

As shown in Table 3, the batteries prepared in Example 1 and Comparative Examples 1 and 2 had the same initial discharging capacity as the reference performance.

<Experimental Example 4>

The batteries prepared in Example 1 and Comparative Examples 1 and 2 were subjected to a current-based charge test, and the results are shown in Table 3 below. The same test was performed on the reference.

Constant current charging time (Min) 0.2C charge 0.5C charge 1.0C charge reference 109.1 6.3 1.1 Example 1 270.6 66.2 9.3 Comparative Example 1 243.1 42.6 3.2 Comparative Example 2 228.8 50.5 7.2

As shown in Table 4, the cells prepared in Example 1 and Comparative Examples 1 and 2 had an increase in the constant current (CC) charging time relative to the reference. However, the battery of Example 1 having a pattern spacing of 500 mu m drastically increased the constant current charging time than the batteries of Comparative Examples 1 and 2.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the present invention is not limited thereto and that various changes and modifications will be apparent to those skilled in the art. It goes without saying that various modifications and variations are possible within the scope of equivalence of the scope.

Claims (9)

An electrode for a secondary battery comprising an electrode current collector and an electrode active material layer formed on at least one surface of the electrode current collector,
Wherein the electrode active material layer has a plurality of dot patterns spaced apart from one another and formed in parallel. The method according to claim 1,
Wherein the plurality of dot patterns have an interval of 400 to 800 占 퐉. The method according to claim 1,
Wherein the diameter of the dot in the dot pattern is 50 to 120 占 퐉. The method according to claim 1,
Wherein the dot pattern has a depth of 5% to 40% of the thickness of the electrode active material layer. The method according to claim 1,
Wherein the dot pattern is formed in the electrode active material layer at an obtuse angle by laser patterning. The method according to claim 1,
The electrode
Wherein the positive electrode is a positive electrode or a negative electrode. A secondary battery in which the electrode for a secondary battery according to any one of claims 1 to 6 is applied as at least one of a positive electrode and a negative electrode. (a) preparing an electrode current collector;
(b) forming an electrode active material layer on at least one of both surfaces of the electrode current collector; And
(c) forming a plurality of dot patterns spaced apart from each other and irradiating a laser beam onto the surface of the electrode active material layer to form a plurality of dot patterns The method of claim 8,
Wherein the plurality of dot patterns have an interval of 400 to 800 占 퐉 in the step (c).

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