KR20200066421A - High power Lithium Ion Battery at elevated temperature with composite heat dissipated material - Google Patents

Abstract

The present invention relates to a lithium secondary battery for a high temperature and high rate with a composite heat dissipation material, which is capable of effectively dissipating heat while rapidly reducing a temperature difference between parts of a battery cell and a temperature difference between battery cells by having optimal values of thicknesses, weights, thermal conductivities and strengths of heat dissipation structures to be arranged between overlapping battery cells; is configured to have the appropriate strength at a low volume and a low weight; and is capable of stably performing a heat dissipation function by securing electrical insulation with the battery cells. According to the present invention, a heat dissipation structure (100) is obtained by sequentially stacking, in the order, a primary heat dissipation layer (110) formed of conductive heat insulating materials to be in close contact with a battery cell; a secondary heat dissipation layer (120) formed of aluminum alloy having the thickness of 0.01-0.2 mm, the thermal conductivity of 160-250 W/mK, the density of 2.5-2.8 g/cm^3, and the yield strength of 200-300 MPa and configured to absorb heat of the battery cell through the primary heat dissipation layer (110); and an electrical insulation layer (130) for insulating electricity. The heat dissipation structures are arranged between a plurality of battery cells.

Description

High power Lithium Ion Battery at elevated temperature with composite heat dissipated material}

The present invention has optimal thickness, thickness, thermal conductivity and strength of the heat dissipation structure to be disposed between the overlapping battery cells, effectively reducing the temperature difference between parts of the battery cell and the temperature difference between the battery cells, and effectively dissipating heat. , Yet it can be configured to have an appropriate strength with low volume and low weight, and also secures electrical insulation with a battery cell, and relates to a lithium secondary battery for high-temperature high-rate using a composite heat dissipation material capable of stably performing a heat dissipation function.

In general, a lithium secondary battery is manufactured by using a battery pack composed of a plurality of unit battery cells connected in series, parallel or in series, and is used for mounting on electric vehicles, drones, electric personal mobility, etc., and repeats charging and discharging in various environments and conditions of use. Therefore, high operational reliability is required.

For example, it is necessary to discharge at a high rate when starting or rapidly accelerating, and frequently charges faster than a slow charge, and may discharge or charge at a high rate even in a high temperature environment in summer.

In this case, the temperature rapidly rises due to the heat generated in each battery cell. If the generated heat is not properly discharged, not only damage caused by overheating reaching the critical temperature (battery ignition point) but also non-uniformity between battery cells occurs. Thus, the battery life is shortened, the battery usage time is shortened, and the stability is also reduced.

Particularly, in order to increase energy density while manufacturing a battery pack in a compact size and light weight, the gap between battery cells is very narrow, so the temperature difference between the battery cells becomes severe, and eventually, some battery cells are damaged depending on the position.

In order to solve the temperature difference and overheating problem between the battery cells, a heat sink is conventionally installed between the battery cells, and heat is radiated from the ends of each heat sink. In addition, by making the heat sink as thin as possible and making the thermal conductivity high, the heat dissipation efficiency was also increased, and an insulating film was formed to minimize the increase in thickness for electrical insulation with the battery cell.

However, since the heat dissipation plate disposed between the battery cells is influenced by heat conductivity and thickness, it is preferable to design it with a heat conductivity and thickness that satisfies both slimness and heat dissipation performance, and furthermore, in shock or vibration applied to the battery pack. By doing so, it may be damaged by friction with the battery cell, and since electrical insulation with the battery pack must also be secured, it is preferable to additionally provide a layer for thermal conductivity, electrical insulation, and cushioning, but this is not the case in the prior art. Designed with emphasis on heat dissipation performance or thickness minimization.

Moreover, the layer for conducting heat to the outside should be properly configured in consideration of a layer that performs heat conduction, electrical insulation, and cushioning.

KR 10-1256063 B1 2013.04.12. KR 10-1731337 B1 2017.04.24. KR 20-2017-0000125 A 2017.01.10.

Therefore, the present invention uses the optimum heat dissipation structure that comprehensively considers thickness, thermal conductivity, strength, insulation, and weight, thereby rapidly discharging heat to the outside while rapidly reducing the temperature difference between parts of the battery cell and the temperature difference between the battery cells, thereby providing high reliability. It is intended to provide a lithium secondary battery for high temperature and high rate with a composite heat dissipation material that is safe and durable by securing electrical insulation and strength.

In order to achieve the above object, the present invention is a lithium secondary battery for high temperature and high rate to which a composite heat dissipation material is applied, with a heat dissipation structure 100 interposed between a plurality of battery cells and sequentially overlapping a plurality of battery cells to dissipate the heat dissipation structure 100 ) To dissipate heat through both ends, the heat dissipation structure 100 is composed of a thermally conductive insulating material, the primary heat dissipation layer 110 in close contact with the battery cell; It is composed of an aluminum alloy with a thickness of 0.01 to 0.2 mm, a thermal conductivity of 160 to 250 W/mK, a density of 2.5 to 2.8 g/cm ³ , and a yield strength of 200 to 300 MPa, through the primary heat dissipation layer 110. A secondary heat dissipation layer 120 that absorbs heat of the battery cell; And an electrical insulation layer 130 for electrical insulation.

According to one embodiment of the invention, the primary heat dissipation layer 110 has a thickness of 0.1 ~ 0.5mm, a thermal conductivity of 3 ~ 15W / mK, a density of 2.5 ~ 3.5g / cm ³ , 0.2 ~ 1N / It consists of a silicone-based rubber having a tensile strength of mm ² and an electrical resistivity of 10 ¹² Ωcm or more.

According to an embodiment of the present invention, the secondary heat dissipation layer 120 contains 1-10 wt% of additives made by selecting one or more of the group of additives consisting of manganese, silicon, magnesium, and zinc, and the balance is 90-99% Is an aluminum alloy made of aluminum, and is formed to a thickness of 0.01 to 0.2 mm.

According to an embodiment of the present invention, the primary heat dissipation layer 110 has a composition of 20 to 30% by weight of silicone rubber, 5 to 10% by weight of silica and 60 to 70% by weight of aluminum oxide, and a thickness of 0.1 to 0.5mm. It is formed of.

According to an embodiment of the present invention, both ends of the secondary heat dissipation layer 120 of the heat dissipation structure 100 are connected to the ends of the secondary heat dissipation layer 120 of different adjacent heat dissipation structures 100, so that a plurality of The heat dissipation structure 100 is connected in succession.

According to an embodiment of the present invention, one end of the second heat dissipation layer 120 of the last heat dissipation structure 100 connected to the other heat dissipation structure 100 is connected to the heat dissipation plate 200 so that the heat dissipation plate 200 ).

According to an embodiment of the present invention, the battery cell is a prismatic battery cell 1, and the heat dissipation structure 100 includes the primary heat dissipation layer 110, the secondary heat dissipation layer 120, and the electrical insulation layer 130. ) Are formed in a plate shape, respectively, to form a plate shape as a whole.

According to an embodiment of the present invention, the battery cell is a cylindrical battery cell (2), a plurality of parallel parallel battery cells (2') arranged in a plurality of cylindrical battery cells (2) in series, the heat dissipation structure (100) is interposed between the battery cell parallel group (2'), the secondary heat dissipation layer 120 and the electrical insulation layer 130 is formed in a plate shape, respectively, the primary heat dissipation layer 110 is Cylindrical battery cells (2) by continuously forming an arcuate groove (111) having a radius of curvature of the outer circumferential surface of the cylindrical battery cells (2) on a plate at intervals of the cylindrical battery cells (1) of the battery cell parallel group (2') Let the face contact.

Since the present invention is configured as described above, the secondary heat dissipation layer 120 for heat dissipation is interposed between the primary heat dissipation layer 110 and the electrical insulation layer 130, so that the heat dissipation structure 100 is interposed between the battery cells. Secondary heat dissipation layer (120) with thickness, thermal conductivity, density and yield strength designed to absorb heat from the cell to dissipate heat, as well as to have electrical stability and durability, and to have a volume, weight, and strength suitable for required heat dissipation performance (120 ), it is possible to suppress the local temperature rise and excessive temperature difference in the battery pack, it is possible to secure the operational reliability.

According to an embodiment of the present invention, the primary heat dissipation layer 110 has a heat conduction function toward the secondary heat dissipation layer 120, an adhesion function with a battery cell, a stable layer maintenance function of the entire heat dissipation structure 100, and a battery cell Since it has a thickness, a thermal conductivity, a density, and a tensile strength capable of faithfully performing all of the electrical insulating functions between the and the second heat dissipation layer 120, the heat dissipation performance as well as the durability are higher.

According to an embodiment of the present invention, by sequentially connecting each heat dissipation structure 100 interposed between the battery cells, while rapidly suppressing the temperature difference between the battery cells, the configuration for discharging heat to the outside of the battery pack is also simplified Can be.

1 is a schematic configuration diagram of a lithium secondary battery according to a first embodiment of the present invention.
Figure 2 is a top view of the interior of the lithium secondary battery according to the first embodiment of the present invention.
3 is a cross-sectional view of a modified embodiment of the heat dissipation structure 100.
4 is a schematic configuration diagram of a lithium secondary battery according to a second embodiment of the present invention.
5 is an internal top view of a lithium secondary battery according to a second embodiment of the present invention.
6 is a graph showing the results of measuring the temperature inside and outside of the battery cell stacking agent while discharging the lithium secondary battery before and after mounting the heat dissipation structure 100 at 1C current.
7 is a graph showing the results of measuring the inside and outside temperature of the battery cell stacking agent while discharging the lithium secondary battery before and after mounting the heat dissipation structure 100 with a 2C current.

The lithium secondary battery according to the present invention is a battery pack that radiates heat through both ends of each heat dissipation structure 100, sequentially stacked with a plurality of battery cells interposed therebetween.

According to the present invention, the heat dissipation structure 100, while minimizing the increase in the volume and weight of the battery pack, to properly dissipate heat to maintain a temperature below the management temperature, in particular, as well as the temperature difference for each part of each battery cell as well as the battery cell It also lowers the temperature difference between the livers sufficiently, and ensures durability by having adequate strength to withstand external shocks or vibrations.

As the heat dissipation structure 100 increases, the volume and weight increase cannot be avoided as the heat dissipation performance is increased, and the volume and weight increase cannot be avoided even if the durability is to be increased.

However, a battery pack constructed by connecting a plurality of battery cells in series, parallel or in series and parallel is sufficient to maintain proper heat dissipation performance under the highest temperature of the environment in use, and electric vehicles and drones that use an electric pack composed of lithium secondary batteries with high durability. In a situation where it is mounted on personal mobility or the like, it is sufficient to satisfy an ideal durability or higher.

Therefore, in the present invention, it is possible to minimize the volume and weight that cannot be coexisted, and to improve the heat dissipation performance and durability to the extent that it can meet the needs of the environment.

To this end, the heat dissipation structure 100 includes a thermally conductive primary heat dissipation layer 110 in close contact with a battery cell; It is composed of an aluminum alloy with a thickness of 0.01 to 0.2 mm, a thermal conductivity of 160 to 250 W/mK, a density of 2.5 to 2.8 g/cm ³ , and a yield strength of 200 to 300 MPa, through the primary heat dissipation layer 110. A secondary heat dissipation layer 120 that absorbs heat of the battery cell; And an electrical insulation layer 130 for electrical insulation of the secondary heat dissipation layer 120.

Accordingly, the secondary heat dissipation layer 120 absorbs heat of the battery cells in close contact with the primary heat dissipation layer 110 formed on the front side of the battery cells on the front and rear sides, and can radiate heat through both ends. The battery cell contacting the formed electrical insulating layer 130 is electrically insulated.

Here, since the thermal conductivity and thickness of the secondary heat dissipation layer 120 determine the heat capacity, the heat dissipation heat is also determined, and the applicant of the present invention is a battery cell size of a lithium secondary battery that is commonly used and a battery composed of the battery cells Considering the size of the pack, etc., while having a heat dissipation performance that satisfies the management temperature and the management temperature difference required for the battery pack, the thickness is as thin as possible, and has an optimal value to meet durability.

That is, the thermal conductivity has a value of 160W/mK or more and 250W/mK or less, and the thickness of the secondary heat dissipation layer 120 is made of aluminum alloy to have a value of 0.01mm or more and 0.2mm or less, and 2.5 to 2.8g/cm. By having a density of ³ , weight increase is also minimized, and by having a yield strength of 200 to 300 MPa, durability is also sufficiently obtained.

It was confirmed that the secondary heat dissipation layer 120 configured as described above satisfies the management temperature and the management temperature difference required for the battery pack of the actual product, while minimizing the increase in volume and weight and also meeting the durability.

If the thermal conductivity is less than 160W/mK, the time required to disperse the amount of heat to be conducted to have a uniform temperature as a whole increases, and eventually, the rate of thermal conductivity toward both ends decreases and exceeds 0.2mm for sufficient heat transfer. Since the thickness of the primary heat dissipation layer 110 and the electrical insulation layer 130, which must have a certain degree of thickness in function, is added, the energy density decrease and space utilization are lowered as the volume of the battery pack increases.

Conversely, when the thermal conductivity exceeds 250 W/mK, the thermal conductivity becomes faster than necessary, and the thickness may be less than 0.01 mm, but durability due to a decrease in strength becomes a problem.

Therefore, the secondary heat dissipation layer 120 is configured to have a value in the range of 160 to 250 W/mK while limiting the thickness within the range of 0.01 to 0.2 mm, thereby increasing the energy density of the battery pack as the volume of the battery pack increases. Even if it decreases, the reduction width of the energy density is minimized as much as possible, the minimum strength is guaranteed, and the heat dissipation characteristics are also satisfied.

In addition, the range of yield strength 200 ~ 300MPa is a material having a thickness of 0.01 ~ 0.2mm, while satisfying the minimum durability not to reach the yield point, it can be said that the range does not need to have more strength than necessary, mounted in the battery pack After that, the stress was generated by applying an external force to check its durability, and the density range of 2.5 to 2.8 g/cm ³ determines the total weight according to the thickness of 0.01 to 0.2 mm. It can be said to be the range that has the minimum value that can be manufactured as a material having a thickness of 0.01 to 0.2 mm, a thermal conductivity of 160 to 250 W/mK, and a yield strength of 200 to 300 MPa while reducing as much as possible.

As described above, the secondary heat dissipation layer 120 having a thickness of 0.01 to 0.2 mm, a thermal conductivity of 160 to 250 W/mK, a density of 2.5 to 2.8 g/cm ³ , and a yield strength of 200 to 300 MPa is manganese and silicon. , 1 to 10% by weight of the additives made by selecting one or more from the group of additives consisting of magnesium and zinc, and the remainder (90 to 99% by weight) could be made of an aluminum alloy made of aluminum. Here, if the additive is less than 1% by weight or more than 10% by weight, it was confirmed that the above-described secondary heat dissipation layer 120 could not be manufactured to have all of the thickness, thermal conductivity, density and yield strength of the above-mentioned. Silver should have a range of 1% by weight or more and 10% by weight or less.

The primary heat dissipation layer 110 has a heat conduction function to conduct heat generated from the battery cell to the secondary heat dissipation layer 110, and has flexibility even when an external shock or vibration is applied, thereby maintaining a close contact with the battery cell, thereby providing heat conduction. A layer having a strength that does not crack and break and maintains a fixed state in the secondary heat dissipation layer 120 so as not to deviate from the secondary heat dissipation layer 120 even when an external shock or vibration is applied to stably perform the It has a holding function and an insulating function to electrically insulate between the battery cell and the secondary heat dissipation layer 120.

However, since it is impossible to perform all of the heat conduction function, the adhesion function, the layer retention function, and the insulation function at its best, in the embodiment of the present invention, the primary heat dissipation layer 110 sufficiently performs each function within the battery pack. To be able to fulfill my role.

According to an embodiment of the present invention, the primary heat dissipation layer 110 has a thickness of 0.1 to 0.5 mm, a thermal conductivity of 3 to 15 W/mK, a density of 2.5 to 3.5 g/cm ³ , and 0.2 to 1 N. It consists of a silicone-based rubber having a tensile strength of /mm ² and an electrical resistivity of 10 ¹² Ωcm or more.

The primary heat dissipation layer 110 is made of a thin thickness in order to minimize the increase in volume, but may have a relatively low thermal conductivity compared to the secondary heat dissipation layer 120, but if it is too thin, electrical insulation and adhesion are also lowered, and impact or It is easy to be damaged by vibration, and further, when the thermal conductivity is high, the electrical insulating property is lowered.

Accordingly, in consideration of shrinkage when in close contact, it is limited to not exceed a maximum thickness of 0.5 mm, and has a thermal conductivity of up to 15 W/mK so as not to increase the thermal conductivity more than necessary without excessively inhibiting electrical insulation, The upper limits of thickness and thermal conductivity were established.

And, in order to have a sufficient adhesion function and a layer retention function, the thickness was set to a lower limit of 0.1 mm, and a relatively small thermal conductivity of 3 W/mK was sufficient, and this value was determined as the lower limit of the thermal conductivity. Accordingly, by lowering the thermal conductivity by an appropriate value when the thickness is thin, electrical insulation can be determined high, and electrical insulation can be secured by providing an electrical resistivity of at least 10 ¹² Ωcm or more.

As a result, the primary heat dissipation layer 110 has a thickness of 0.1 to 0.5 mm, a thermal conductivity of 3 to 15 W/mK, and an electrical resistivity of 10 ¹² Ωcm or more, while taking into account the thickness range, 0.2 to 1 N/mm ² By having a tensile strength and constructing a silicon-based rubber to have a density of 2.5 to 3.5 g/cm ³ , it is possible to faithfully perform all of the heat conduction function, adhesion function, layer retention function, and insulation function.

The primary heat dissipation layer 110 could be produced in a composition of 20 to 30% by weight of silicone rubber, 5 to 10% by weight of reinforcing material, and 60 to 70% by weight of thermal conductive material. Here, the reinforcing material can be made of silica, and the heat conducting material can be made of aluminum oxide.

The electrical insulating layer 130 is a layer for electrically insulating a surface opposite to the surface insulated by the primary heat dissipation layer 110 among both surfaces of the plate-shaped secondary heat dissipation layer 120, and if possible, as thin and electrically insulating. If you secure it, you are satisfied.

However, although the electrical insulation layer 130 may be formed by surface treatment of the secondary heat dissipation layer 120, considering that the electrical insulation layer 130 may also be worn in contact with a battery cell, silicon-based It is good to be composed of rubber. For example, if only pure electrical insulation is to be secured, the electrical insulation layer 130 may not have a thermal conductive material added, so that it may have a relatively thin thickness compared to the primary heat dissipation layer 110. . However, the electrical insulating layer 130 may be configured to contribute to heat dissipation, in this case, the same as the primary heat dissipation layer 110, or to include a thermal conductive material to increase the thermal conductivity but increase the content relative It may be made to be relatively thin than the primary heat dissipation layer 110.

As described above, the heat dissipation structure 100 having the primary heat dissipation layer 110, the secondary heat dissipation layer 120, and the electrical insulating layer 130 is interposed between the battery cells, and the secondary heat dissipation layer Both ends of the (120) are extended, and heat is radiated to the extended portion.

At this time, since all the battery cells constituting the battery pack must be in close contact with the primary heat dissipation layer 110 without omission, all the heat dissipation structures 100 are battery cells such that the primary heat dissipation layer 110 faces the same direction. It must be interposed.

However, it is preferable to radiate heat while reducing the temperature difference between the plurality of battery cells, and in fact, even if the heat dissipation to the outside of the battery pack is slow, the temperature difference between the battery cells is quickly reduced to solve the imbalance between the battery cells and high-rate charging and discharging under a high temperature environment. It also solves the problem of reduced stability caused by overheating and imbalance, shortened battery life and reduced usable time.

Accordingly, both ends of the secondary heat dissipation layer 120 of the heat dissipation structure 100 interposed between the battery cells are connected to the ends of the secondary heat dissipation layer 120 of different heat dissipation structures 100. That is, the plurality of heat dissipation structures 100 are connected in series to the provided secondary heat dissipation layer 120 to be connected in succession.

Then, one end that is not connected to the other heat dissipation structure 100 among both ends of the second heat dissipation layer 120 of the last heat dissipation structure 100 is connected to the heat dissipation plate 200 to radiate heat to the heat dissipation plate 200.

Hereinafter, structural features of the lithium secondary battery according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

<First embodiment of the present invention>

1 is a schematic configuration diagram of a lithium secondary battery according to a first embodiment of the present invention. 1, the rectangular battery cell 1 built in the case 10 is shown in perspective. For the heat dissipation structure 100, only the upper side of the portion hidden by the rectangular battery cell 1 is shown in perspective. The arrangement of the prismatic battery cells 1 and the continuous continuous state of the prismatic battery cells 1 can be easily recognized.

2 is a perspective view showing a lithium secondary battery according to a first embodiment of the present invention.

1 and 2, a lithium secondary battery is a battery pack constructed by stacking a plurality of square battery cells 1 in the case 10 with the heat dissipation structure 100 interposed therebetween.

In addition, since the first or last arrangement of the prismatic battery cells 1 does not have the heat dissipation structure 100 contacting the primary heat dissipation layer 110, the heat dissipation structure 100 is additionally installed on the outer side.

Since the prismatic battery cell 1 has a rectangular parallelepiped shape, and is provided with a terminal on one side (the upper side in the figure) of the non-overlapping side, it can be electrically connected in series, parallel or in parallel, so the heat dissipation structure ( 100) the primary heat dissipation layer 110, the secondary heat dissipation layer 120 and the electrical insulation layer 130 is formed in a plate shape, respectively, it is sufficient to have a plate shape.

Thus, each heat dissipation structure 100 has a stacked stacked in parallel with each other spaced apart by the thickness of the square battery cell (1).

In addition, each heat dissipation structure 100 has a secondary heat dissipation layer 120 protruding out of a surface (a side in the drawing) in which a battery cell electrode is not formed among the stacks of the square battery cells 1. And, by bending the protruding portion of the secondary heat dissipation layer 120, so as to be connected to the secondary heat dissipation layer 120 of the adjacent heat dissipation structure 100, the protruding portions on both sides of the secondary heat dissipation structure 100 are different The heat dissipation layer 120 is connected to the heat dissipation layer 120, and the other heat dissipation structure 100 is connected to the second heat dissipation layer 120 in series.

Of course, since all of the prismatic battery cells 1 are in contact with the primary heat dissipation layer 110 of the heat dissipation structure 100, either one of the two surfaces comes into contact with the rapid thermal heat dissipation path by the heat dissipation structure 100.

On the other hand, by mutually connecting the protrusions of the facing secondary heat dissipation layer 120, there is a fear that the protrusions contact the prismatic battery cell 1. Thus, as shown in Figures 1 and 2, the electrical insulating layer 130 is formed to extend one end at both ends to the protrusions of the secondary heat dissipation layer 120 to cover the side surfaces of the prismatic battery cell 1. It is good.

Here, the connection method between the secondary heat dissipation layers 120 is, in addition to the method of overlapping and bonding as shown, for example, symmetrically bends to make contact, then welds or otherwise penetrates with a bolt and then tightens the nut to compress it. You can also do it in a way.

In addition, the second heat dissipation layer 120 of the last one disposed among the plurality of heat dissipation structures 100 has a case 10 at one end, which is not connected to the second heat dissipation layer 120 of the other heat dissipation structure 100 among both ends. It was extended to the outside, so that it was connected to the heat sink 200 installed outside the case 10. Here, the heat sink 200 is illustratively shown as having a cooling fin 210 that increases the contact area with external air, such that it is cooled by natural air convection or forcedly cooled by a fan. It can be cooled. Of course, the heat sink 200 may be cooled by water cooling.

As described above, the lithium secondary battery composed of a battery pack incorporating a prismatic battery cell 1 has a primary heat dissipation layer 110 capable of faithfully performing all of the heat conduction function, adhesion function, layer retention function and insulation function as described above. ) Stably maintains the adhesion state and insulation state of the prismatic battery cell 1 and the heat dissipation structure 100 and is not damaged, and absorbs heat generated from the battery cell 1 into the secondary heat dissipation layer 120. . In addition, the heat absorbed by the secondary heat dissipation layer 120 is dispersed in the secondary heat dissipation layer 120 to prevent local overheating, so that the temperature difference between the parts in each battery cell 1 and the temperature difference between the battery cells 1 is also quickly. By reducing it, the imbalance problem is solved, and heat is radiated to the heat sink 200, thereby reducing the total amount of heat in the battery pack, thereby reducing the battery life due to local overheating, shortening the use time, and reducing stability.

<Modification of the first embodiment of the present invention>

3 is a cross-sectional view of a modified embodiment of the heat dissipation structure 100.

First, referring to FIG. 3(a), the secondary heat dissipation layer 120 has a long formed plate-like shape, and the primary heat dissipation layer 110 follows the longitudinal direction of the secondary heat dissipation layer 120 and is a prismatic battery. It is formed on the secondary heat dissipation layer 120 at intervals d by the thickness of the cell 1, and is formed on selected surfaces alternately on both sides of the secondary heat dissipation layer 120.

The electrical insulating layer 130 is formed to face the primary heat dissipation layer 110 with the secondary heat dissipation layer 120 interposed therebetween, extending by the thickness of the prismatic battery cell 1, and adjoining 1 formed on the same surface. The heat dissipation layer 110 is brought into contact. As such, the extended surface of the electrical insulating layer 130 is a surface for covering the side surface of the prismatic battery cell 1 as shown in FIG. 1.

In other words, the primary heat dissipation layer 110 is formed on the upper and lower surfaces of the upper and lower surfaces of the secondary heat dissipation layer 120, and an electrical insulating layer 130 is formed on the lower surface, but extended by the thickness of the prismatic battery cell 1, When the first primary heat dissipation layer 110 is formed at a distance d by the thickness of the prismatic battery cell 1 and then the primary heat dissipation layer 110 is formed, it is formed on the lower surface, and the electrical insulating layer 130 is formed. Silver is formed on the upper surface but extends as much as the thickness of the prismatic battery cell 1, and the pair of the primary heat dissipation layer 110 and the electrical insulation layer 130 formed on the upper and lower surfaces is the secondary heat dissipation layer 120. It is formed sequentially along the longitudinal direction.

By bending the heat dissipation structure 100 configured as described above along the boundary lines of both ends of each primary heat dissipation layer 110, the primary heat dissipation layer 110 and the electrical insulation layer 130 are prismatic battery cells as shown in FIG. 1. (1) can be installed to be disposed between the prismatic battery cells 1 so as to contact. Accordingly, as described with reference to FIG. 1, there is no need to connect the heat dissipation structures 100 interposed between the square battery cells 1 to each other. In addition, the volume of the battery pack can be reduced as much as there is no space for connection.

Next, referring to FIG. 3(b), FIG. 3 is a point in which the direction in which the electrical insulating layer 130 is extended by the thickness of the prismatic battery cell 1 is directed toward the primary heat dissipation layer 110 that was previously formed. It differs from that shown in (a).

The difference between FIGS. 3(a) and 3(b) occurs according to a direction in which the secondary heat dissipation layer 120 is bent at an angle of 90° at the end of the primary heat dissipation layer 110. That is, when installing by bending toward the primary heat dissipation layer 110, the electrical insulation layer 130 is formed from the end of the primary heat dissipation layer 110, and bent in a direction opposite to the primary heat dissipation layer 110. In the case of installation, the electrical insulation layer 130 is extended on the opposite side of the primary heat dissipation layer 110.

<Second embodiment of the present invention>

4 is a schematic configuration diagram of a lithium secondary battery according to a second embodiment of the present invention. 4, the interior of the lithium secondary battery is illustrated in a perspective view.

5 is a perspective view showing the interior of the lithium secondary battery according to the second embodiment of the present invention.

According to the lithium secondary battery illustrated in FIGS. 4 and 5, a plurality of parallel battery cells 2'arranged in a plurality of cylindrical battery cells 2 in series are provided to sequentially overlap within the battery pack case 10. Is laid. That is, in contrast to the lithium secondary battery shown in FIG. 1, it can be seen that the battery cell parallel group 2 ′ of the cylindrical battery cell 2 is placed at the position where the prismatic battery cell 1 is placed.

Accordingly, the heat dissipation structure 100 may be interposed between the battery cells parallel group 2'.

By the way, when the primary heat dissipation layer 110, the secondary heat dissipation layer 120, and the electrical insulation layer 130 of the heat dissipation structure 110 are respectively formed in a plate shape, the primary heat dissipation layer 110 is a battery cell parallel group It is in line contact with each cylindrical battery cell 2 of (2'), and heat dissipation is poor.

Thus, the primary heat dissipation layer 110 has an arcuate groove 111.

The arc-shaped groove 111 is formed by having a protrusion on a plate-like structure having a thickness in the range of 0.1 to 0.5 mm as described above, and having a radius of curvature on the outer circumferential surface of the cylindrical battery cell 2, and paralleling the battery cells Cylindrical battery cells 1 of group 2'are continuously formed at intervals.

Since the heat dissipation structure 100 configured as described above is in a state interposed between the battery cells parallel group 2', the primary heat dissipation layer 110 is in surface contact with the battery cells parallel group 2', so that the cylindrical battery cell The heat generated in (2) can be quickly absorbed.

In addition, as described with reference to FIG. 3, the embodiment illustrated in FIGS. 4 and 5 is configured as an integral type so that the heat dissipating structures 100 interposed between the battery cell parallel groups 2 ′ are mutually connected. It is easy and can be manufactured by reducing the size of the battery pack. However, the portions connecting the interposed portions between the battery cell parallel groups 2'can be in contact with the cylindrical battery cells 2, and in this case, the separation distance between the primary heat dissipation layers 110 is cylindrical. The circumferential length of the battery cell 2 is set to half of the circumference (circumference according to the diameter of the outer circumference), and the electrical insulating layer 130 must be extended by the length of the half.

<1st verification of temperature uniformity>

In order to verify the temperature uniformity between battery cells of the lithium secondary battery according to the present invention, after preparing 12 square battery cells 1 having an average voltage of 3.7V and a capacity of 22AH, the heat dissipation structure 100 is a square battery cell ( Twelve prismatic battery cells 1 were arranged in parallel so as to pass closely between 1), and twelve prismatic battery cells 1 were electrically connected in series to form a rated 44V battery pack.

Then, the temperature difference between the prismatic battery cells 1 appearing in the lithium secondary battery before and after mounting the heat dissipation structure 100 was first verified.

First, by dismounting the heat dissipation structure 100 that was mounted, a battery pack in which the heat dissipation structure 100 is not mounted was prepared.

After the battery pack before mounting the heat dissipation structure 100 was fully charged at room temperature, it was allowed to stand for a period of time under an environment of high temperature of 50°C, and then discharged at a high rate up to 41V with a current of 1C (22A) while maintaining high temperature of 50°C. During the high-rate discharge, the temperature was measured at the central portion and the outer surface portion of the battery cell stack to obtain a graph of FIG. 6(a).

Here, the center portion of the temperature measurement is the battery cell stacked at the innermost, and the outer surface portion of the temperature measurement is the battery cell stacked at the outermost.

Looking at the graph of FIG. 6(a), the temperature difference between the central portion temperature and the surface portion temperature gradually increased as the discharge time elapsed, and reached about 12° C. at about 1 hour. Since it was discharged with 1C (22A) current, the discharge current decreased and the temperature gradually decreased, and the temperature difference decreased slightly.

Next, a battery pack equipped with a heat dissipation structure 100 was prepared.

After the heat dissipation structure 100 is installed, the battery pack with the heat dissipation structure 100 is fully charged in the same manner as the battery pack, and after standing at a high temperature of 50°C for a certain period of time, 41V at a current of 1C (22A) under a high temperature of 50°C environment. High rate discharge until. The heat sink 200 is exposed to an environment at a high temperature of 50°C.

During the high-rate discharge, the central portion temperature and the surface portion temperature were detected to obtain a graph of FIG. 6(b).

Looking at the graph of FIG. 6(b), the temperature difference between the central temperature and the surface temperature gradually increases as the discharge time elapses, but the rate of increase is slower than before the heat dissipation structure 100 is mounted, and at about 1 hour It reached about 7°C. That is, the heat dissipation structure 100 is reduced by approximately 5 ℃ compared to before installation. In addition, the temperature difference was lower than before the heat dissipation structure 100 was installed even when the temperature gradually decreased.

As a result of the comparison, it was confirmed that the temperature difference between the battery cells can be significantly reduced by mounting the heat dissipation structure 100.

The reason why the temperature of the surface portion is high and the temperature of the central portion cannot be sufficiently lowered is because the amount of heat dissipated to the outside of the battery pack is small by dissipating the heat sink 200 exposed under a high temperature environment. However, since the temperature difference between the battery cells can be significantly reduced, if it is possible to sufficiently dissipate heat through the heat sink 200, the central portion temperature and the surface portion temperature can also be significantly reduced.

On the other hand, when the heat dissipation structure 100 is mounted, it can be confirmed by comparing FIG. 6(a) and FIG. 6(b) that the discharge time is increased, thereby obtaining an effect of extending the use time, and the heat sink ( By increasing the amount of heat dissipation through 200), the use time can be further extended.

<2nd verification of temperature uniformity>

This secondary verification was performed in the same manner as the primary verification except that the discharge current was adjusted upward from 1C (22A) current to 2C (44A).

7(a) is a graph obtained by detecting the temperature of the central portion and the outer surface portion while discharging the lithium secondary battery before the heat dissipation structure 100 is mounted.

Looking at the graph of FIG. 7(a), the temperature of the central portion and the outer surface portion rises more rapidly than when discharged with 1C(22A) current, and the temperature difference increases more rapidly, and the temperature difference of 13℃ after 30 minutes Reached. Thereafter, as the temperature decreased, the temperature difference tended to decrease again.

7(b) is a graph obtained by detecting the central portion temperature and the outer surface portion temperature during discharge of the lithium secondary battery after the heat dissipation structure 100 is mounted.

Looking at the graph of FIG. 7(b), the central temperature and the outer surface temperature rise at a slower rate than before the heat dissipation structure 100 is mounted, and the temperature difference increases, but it is more noticeable than before the heat dissipation structure 100 is mounted. Significantly, the rate of increase is low, and the temperature reaches its peak at a later point than before the heat dissipation structure 100 is installed, and the temperature difference at this time is 8°C. That is, it was possible to lower the temperature of approximately 5°C than before the heat dissipation structure 100 was mounted. Thereafter, it was found that the temperature difference was almost maintained while the temperature was falling.

As a result of comparison, by mounting the heat dissipation structure 100 even at a high rate discharge of 2C (44A), the temperature difference between the battery cells can be significantly reduced, and the temperature rise rate is also slowed down, thereby reducing the temperature difference between the battery cells and increasing the use time. It was confirmed that there was.

Therefore, it can be seen that the heat dissipation structure 100 provided by the present invention rapidly absorbs heat generated in the battery cell and uniformly disperses the absorbed heat to all parts to make the temperature uniform. In addition, heat can be quickly released through the heat sink 200. Since the temperature of all parts can be rapidly lowered according to heat release, the temperature difference between battery cells is significantly and rapidly reduced to solve the imbalance phenomenon by location of the battery cells, and heat generated from the battery cells is quickly released, thereby overheating. It can be prevented, and eventually, the lithium secondary battery ensures stability, battery life and usage time.

In the above, in order to illustrate the technical spirit of the present invention, a specific embodiment is illustrated and described, but the present invention is not limited to the same configuration and operation as the specific embodiment as described above, and various modifications are within the limits of the present invention. Can be carried out at Therefore, such modifications should also be regarded as belonging to the scope of the present invention, and the scope of the present invention should be determined by the claims below.

1: Square battery cell
2: Cylindrical battery cell 2': Battery cell parallel group
10: case
100: heat dissipation structure
110: primary heat dissipation layer 111: arc-shaped groove
120: secondary heat dissipation layer
130: electrical insulating layer
200: heat sink
210: cooling fin

Claims (8)

The heat dissipation structure 100 is interposed between the plurality of battery cells, and the plurality of battery cells are sequentially stacked to radiate heat through both ends of the heat dissipation structure 100,
The heat dissipation structure 100
Primary heat dissipation layer 110 made of a thermally conductive insulating material and in close contact with the battery cell;
It is composed of an aluminum alloy with a thickness of 0.01 to 0.2 mm, a thermal conductivity of 160 to 250 W/mK, a density of 2.5 to 2.8 g/cm ³ , and a yield strength of 200 to 300 MPa, through the primary heat dissipation layer 110. A secondary heat dissipation layer 120 that absorbs heat of the battery cell; And
An electrical insulating layer 130 for electrical insulation;
Stacked in the order of
Lithium secondary battery. According to claim 1,
The primary heat dissipation layer 110 is
A silicon series with a thickness of 0.1 to 0.5 mm, a thermal conductivity of 3 to 15 W/mK, a density of 2.5 to 3.5 g/cm ³ , a tensile strength of 0.2 to 1 N/mm ² , and an electrical resistivity of 10 ¹² Ωcm or more. Made of rubber
Lithium secondary battery. According to claim 1,
The secondary heat dissipation layer 120
Manganese, silicon, magnesium, and one or more additives made by selecting one or more of the group consisting of zinc is contained 1 to 10% by weight, the remainder 90 to 99% is an aluminum alloy made of aluminum, formed of 0.01 to 0.2mm thick
Lithium secondary battery. According to claim 1,
The primary heat dissipation layer 110 is
It has a composition of 20 to 30% by weight of silicone rubber, 5 to 10% by weight of silica and 60 to 70% by weight of aluminum oxide, and is formed in a thickness of 0.1 to 0.5mm.
Lithium secondary battery. According to claim 1,
Both ends of the secondary heat dissipation layer 120 of the heat dissipation structure 100 are connected to the ends of the secondary heat dissipation layer 120 of adjacent different heat dissipation structures 100, so that the plurality of heat dissipation structures 100 are successively connected. Made
Lithium secondary battery. The method of claim 5,
Among the ends of the second heat dissipation layer 120 of the last connected heat dissipation structure 100, one end that is not connected to the other heat dissipation structure 100 is connected to the heat dissipation plate 200 so that the heat dissipation plate 200 dissipates heat.
Lithium secondary battery. According to claim 1,
The battery cell is a prismatic battery cell (1),
The heat dissipation structure 100 forms the first heat dissipation layer 110, the second heat dissipation layer 120, and the electrical insulation layer 130 in the form of a plate, thereby forming a plate shape as a whole.
Lithium secondary battery. According to claim 1,
The battery cell is a cylindrical battery cell (2),
A plurality of parallel parallel battery cells (2') in which a plurality of cylindrical battery cells (2) are arranged in a row, are sequentially stacked,
The heat dissipation structure 100 is interposed between the battery cells parallel group (2'), the secondary heat dissipation layer 120 and the electrical insulation layer 130 is formed in a plate shape, respectively, the primary heat dissipation layer ( 110) is a cylindrical battery cell, such that the circular groove 111 having an outer peripheral surface curvature radius of the cylindrical battery cell 2 is continuously formed at intervals of the cylindrical battery cells 1 of the battery cell parallel group 2'. (2)
Lithium secondary battery.

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