Battery module

Abstract

Provided are a battery module, a method of manufacturing the same, and a resin composition applied to the method of manufacturing the same. A battery module manufactured with a simple process and low cost but having excellent output for the size thereof, a method of manufacturing the same, and a resin composition applied to the method of manufacturing the same are provided in the present invention.

Claims

1. A method of manufacturing a battery module, comprising: injecting a resin composition into a module case of a battery module, the module case including a lower plate and a sidewall forming an inside space, and the resin composition being a room temperature curing type resin composition; accommodating a plurality of battery cells in the inside space of the module case such that a first end portion of each of the battery cells faces the lower plate, each of the plurality of battery cells having a second end portion opposite to the first end portion; and after the step of accommodating the plurality of battery cells in the inside space, curing the resin composition in the inside space of the module case so as to form a resin layer therein, the curing being performed by maintaining the injected resin composition at room temperature, wherein the resin layer partially fills the inside space of the module case, such that the resin layer contacts the lower plate of the module case and each of the first end portions of the plurality of battery cells, but the resin layer does not contact each of the second end portions of the plurality of battery cells.

2. The method of claim 1, wherein the resin composition is injected into the inside space of the module case after the step of accommodating the plurality of battery cells in the inside space, and wherein the resin composition is injected into the inside space through an injection hole provided in the lower plate or the sidewall.

3. The method of claim 2, wherein the lower plate or the sidewall in which the injection hole is provided includes an observation hole.

4. The method of claim 1, wherein the resin layer comprises thermally conductive fillers and has thermal conductivity of 1.5 W/mK or more.

5. The method of claim 4, wherein the thermally conductive fillers are ceramic particles.

6. The method of claim 1, wherein the resin layer is formed so as to conform to the plurality of battery cells.

7. The method of claim 1, wherein the sidewall or the lower plate in contact with the resin layer includes a thermally conductive region.

8. The method of claim 7, wherein a contact ratio of the resin layer to the thermally conductive region is 80% or more of the entire area of the thermally conductive region.

9. The method of claim 1, wherein the resin layer comprises thermally conductive fillers and has thermal conductivity of 2 W/mK or more.

10. The method of claim 1, wherein the resin layer has an insulation breakdown voltage of 10 kV/mm or more.

11. The method of claim 1, wherein the resin layer has adhesion strength of 1,000 gf/10 mm or less.

12. The method of claim 1, wherein the resin layer has a specific gravity of 5 or less.

13. The method of claim 1, wherein a shore A hardness of the resin layer is less than 100 or a shore D hardness is 70 or less.

14. The method of claim 1, wherein, in a thermogravimetric analysis (TGA), the amount of residue of the resin layer at 800° C. is 70 weight % or more.

15. The method of claim 1, wherein the resin layer includes an acrylic resin, an epoxy resin, an urethane resin, an olefin resin, an ethylene vinyl acetate (EVA) resin, or a silicone resin.

16. The method of claim 1, wherein the resin layer includes a thixotropic additive, a diluent, a dispersant, a surface treatment agent, a flame retardant, or a coupling agent.

17. The method of claim 1, wherein the resin layer has a thickness in a range of 100 μm to 5 mm.

18. The method of claim 1, wherein the step of curing the resin composition is performed while the resin composition is in contact with the plurality of battery cells.

Description

DESCRIPTION OF DRAWINGS

(1) FIG. 1 is a schematic view illustrating an example of a module case that may be applied to the present invention.

(2) FIG. 2 is a view illustrating battery cells accommodated in the module case.

(3) FIG. 3 is a view illustrating an example of a lower plate in which injection holes and observation holes are formed.

(4) FIGS. 4 and 5 are schematic views illustrating examples of battery pouches which may be used as the battery cells.

(5) FIGS. 6 to 8 are schematic views illustrating examples of structures of the battery module.

REFERENCE NUMERALS

(6) 10: MODULE CASE

(7) 10A: LOWER PLATE

(8) 10B: SIDEWALL

(9) 10C: UPPER PLATE

(10) 10D: GUIDING PORTION

(11) 20: BATTERY CELL

(12) 30: RESIN LAYER

(13) 50A: INJECTION HOLE

(14) 50B: OBSERVATION HOLE

(15) 40: INSULATING LAYER

(16) 100: POUCH TYPE CELL

(17) 110: ELECTRODE ASSEMBLY

(18) 120: EXTERIOR MATERIAL

(19) 121: UPPER POUCH

(20) 122: LOWER POUCH

(21) S: SEALING PORTION

MODES OF THE INVENTION

(22) Hereinafter, although the present invention will be described with reference to examples and comparative examples, the scope of the present invention is not limited to the scope that will be described below.

(23) 1. Method of Measuring Thermal Conductivity of Resin Layer

(24) Thermal conductivity of a resin layer was measured based on ASTM D5470 standard. That is, based on ASTM D5470 standard, a thermal equilibrium state (temperature change is approximately 0.1° C. or less in five minutes) was reached by positioning the resin layer between two copper bars, having one of the two copper bars be in contact with a heater, having the other be in contact with a cooler, maintaining the heater at a constant temperature, and adjusting the capacity of the cooler. The temperature of each copper bar was measured in the thermal equilibrium state, and thermal conductivity K (unit: W/mK) was evaluated using the following equation. During evaluating the thermal conductivity, pressure applied to the resin layer was adjusted to be approximately 11 Kg/25 cm.sup.2, and when the thickness of the resin layer was changed during measurement, the thermal conductivity was calculated based on a final thickness.

(25) <Equation of Thermal Conductivity>
K=(Q×dx)/(A×dT)

(26) In Equation of thermal conductivity, K denotes thermal conductivity (W/mK), Q denotes heat that transfers per unit time (unit: W), dx denotes a thickness of the resin layer (unit: m), A denotes a cross-sectional area of the resin layer (unit: m2), and dT denotes a temperature difference of the copper bars (unit: K).

(27) 2. Method for Evaluating Specific Gravity

(28) Specific gravity of the resin layer was measured based on ASTM D792 standard. For example, the weight of the resin layer is measured based on the standard, the weight is then measured again in water, and density and specific gravity may be calculated using the difference between the measured weights, or a predetermined amount of power or pellet (for example, approximately 5 g) is put into a premeasured volume with a pyrometer, and the specific gravity may be calculated using differences of the weight and volume thereof at 73.4° F.

(29) 3. Method of Thermogravimetric Analysis (TGA).

(30) TGA was performed using an instrument, TA400 made by TA Instruments. The analysis was performed using a resin layer of approximately 10 mg, at a temperature in a range of 25° C. to 800° C., at heating speed of 20° C./min, and under an N.sub.2 atmosphere of 60 cm.sup.3/min.

(31) 4. Measurement of Insulation Breakdown Voltage

(32) An insulation breakdown voltage of the resin layer was evaluated based on ASTM D149 standard. The insulation breakdown voltage refers to a voltage applied up to the moment at which a material loses insulation properties, the insulation properties disappear as conductivity is rapidly increased at a high voltage of a certain level or more. The breakdown voltage refers to a minimum voltage required for causing an insulation breakdown, and the insulation properties are generated by completely generating an arc through a specimen. A voltage gradient may be obtained by dividing a voltage at the moment at which a breakdown occurs by an insulation thickness. The insulation breakdown voltage was measured using an instrument, PA70-1005/202 made by Backman Industrial Co., and here, the thickness of the specimen (resin layer) was approximately 2 mm, and the diameter was approximately 100 mm 5. Measurement of Adhesion Strength

(33) A lower plate of a module case formed of aluminum in which an insulation film (epoxy and/or polyester based insulating layer) and a polyethylene terephthalate (PET) film were attached using a resin layer, and here, the width of attachment was approximately 10 mm Here, the thickness of the resin layer was approximately 1 mm. The attachment was performed by loading an uncured resin composition between the insulation film and the PET film and curing the resin composition. Next, adhesion strength was measured while the PET film was being delaminated at speed of approximately 300 mm/min and a delamination angle of 180°.

(34) 6. Measurement of Hardness

(35) Hardness of a resin layer was measured based on ASTM D 2240, and JIS K 6253 standards. ASKER, a durometer hardness instrument, was used for measuring the hardness. Initial hardness was measured by applying a weight of 1 Kg or more (approximately 1.5 Kg) to a flat sample (the resin layer), and hardness was evaluated by confirming a stable measurement value after 15 seconds.

(36) 7. Reliability Evaluation of Battery Module.

(37) Reliability of a battery module was evaluated by measuring thermal conductivity and a withstand voltage of the module. The withstand voltage is measured for checking the highest applied voltage up to which the battery module tolerates without breaking down. In below examples and comparative examples, the withstand voltage was measured while an applied voltage was started from approximately 1.2 kV and increased. The thermal resistance of the battery module was evaluated by positioning the module between upper and lower blocks of the measurement instrument, executing DynTIM Tester software on a controlling computer, determining and inputting a heating current and measurement time in the software, completing setting of parameters such as the measurement pressure and measurement condition of the thermal resistance, and measuring the thermal resistance depending on the measurement conditions by using a T3Ster and DynTIM tester controlled by software. Reliability according to each evaluation result was classified based on below reference.

(38) <Reliability Evaluation Reference according to Withstand Voltage Resistance>

(39) Good: Withstand voltage is 2 kV or more.

(40) Fair: Withstand voltage is less than 2 kV and 0.5 kV or more.

(41) Poor: Withstand voltage is less than 0.5 kV.

(42) <Reliability Evaluation Reference according to Thermal Resistance Evaluation>

(43) Good: Thermal resistance is 2 K/W or less

(44) Fair: Thermal resistance is greater than 2 K/W and 6 K/W or less.

(45) Poor: Thermal resistance is greater than 6 K/W.

EXAMPLE 1

(46) Resin Composition Preparation

(47) A resin composition with viscosity of approximately 250,000 cP at room temperature was prepared by mixing an amount of alumina (particle size distribution: 1 to 60 μm) into a two-component urethane based adhesive composition (main material: HP-3753 (KPX Chemical Co., Ltd) and hardener: TLA-100 (AsshiKASEI)) such that the two-component urethane based adhesive composition has thermal conductivity of approximately 3 W/mK after curing (in a range of approximately 600 to 900 parts by weight with respect to 100 parts by weight of the total two-components solid content), and the resin composition was applied to preparing a battery module.

(48) Battery Module Manufacturing

(49) A battery module was formed using a module case that is in the shape shown in FIG. 1 and includes a lower plate, a sidewall, and an upper plate formed of aluminum. A guiding portion that guides installation of battery cells was formed on an inside surface of the lower plate of the module case. Injection holes for injecting a resin composition were formed at a regular gap in a central portion of the lower plate of the module case. Observation holes were formed at end portions of the lower plate. A bundled pouch in which a plurality of battery pouches were stacked was accommodated in the module case. Then, the top surface of the module case was covered by the upper plate. Next, the prepared resin composition was injected until it was confirmed that the resin composition reached the observation holes, and then the battery module was manufactured by curing the resin composition.

EXAMPLE 2

(50) Resin Composition Preparation

(51) A resin composition with viscosity of approximately 130,000 cP at room temperature was prepared by mixing an amount of alumina (particle size distribution: 1 to 60 μm) into a two-components silicone based adhesive composition (main material: SL5100A (KCC Corporation), hardener: SL5100B (KCC Corporation)) such that the two-component silicone based adhesive composition had thermal conductivity of approximately 3 W/mK after curing (in a range of approximately 800 to 1200 parts by weight with respect to 100 parts by weight of the total two-components solid content), and the resin composition was applied to manufacturing the following battery module.

(52) Battery Module Manufacturing

(53) A battery module was used that had the same structure as that of the Example 1 however in which an injection hole and an observation hole for injecting a resin composition were not formed. The battery module was manufactured by coating a front surface of an inside surface of the corresponding case with the prepared resin composition with a thickness of approximately 500 μm, accommodating the same battery cells as that of the Example 1, covering an upper plate, and curing a layer of the resin composition.

EXAMPLE 3

(54) A battery was identically manufactured with that of the Example 1 except using a resin composition whose viscosity was adjusted to approximately 350,000 cP at room temperature by mixing an amount of alumina (particle size distribution: 1 to 60 μm) into a two-component urethane based adhesive composition (main material: PP-2000(KPX Chemical), hardener: TLA-100 (AsshiKASEI)) such that the two-components urethane based adhesive composition had thermal conductivity of approximately 3.5 W/mK after curing (in a range of approximately 600 to 900 parts by weight with respect to of 100 parts by weight of the total two-components solid content).

EXAMPLE 4

(55) A battery was identically manufactured with that of the Example 1 except using a resin composition whose viscosity was adjusted to approximately 500,000 cP at room temperature by mixing an amount of alumina (particle size distribution: 1 to 60 μm) into an adhesive composition having an epoxy based room temperature curing type made by KUKDO Chemical Co., Ltd such that the adhesive composition had thermal conductivity of approximately 3 W/mK after curing (in a range of approximately 600 to 900 parts by weight with respect to 100 parts by weight of the total two-components solid content).

EXAMPLE 5

(56) A battery was identically manufactured with that of the Example 2 except using a resin composition whose viscosity was adjusted to approximately 2,000,000 cP at room temperature by mixing an amount of graphite into a two-component silicone based adhesive composition (main material: SL5100A (KCC Corporation), hardener: SL5100B (KCC Corporation)) such that the two-component silicon based adhesive composition had thermal conductivity of approximately 1.5 W/mK after curing (in a range of approximately 100 to 300 parts by weight with respect to 100 parts by weight of the total two-components solid content).

EXAMPLE 6

(57) A battery was identically manufactured with that of the Example 2 except using a resin composition whose viscosity was adjusted to approximately 100,000 cP at room temperature by mixing an amount of alumina (particle size distribution: 1 to 60 μm) into a two-component silicone based adhesive composition (main material: SL5100A (KCC Corporation), hardener: SL5100B (KCC Corporation)) such that the adhesive composition had thermal conductivity of approximately 1.5 W/mK after curing (in a range of approximately 300 to 500 parts by weight with respect to of the total two-components solid content 100 parts by weight of the total two-components solid content).

EXAMPLE 7

(58) A battery was identically manufactured with that of the Example 1 except using a resin composition whose viscosity was adjusted to approximately 150,000 cP at room temperature by mixing an amount of alumina (particle size distribution: 1 to 60 μm) into a two-component urethane based adhesive composition (main material: PP-2000(KPX Chemical), hardener: TLA-100 (AsshiKASEI)) such that the two-component urethane based adhesive composition had thermal conductivity of approximately 2 W/mK after curing (in a range of approximately 400 to 900 parts by weight with respect to 100 parts by weight of the total two-components solid content) to the two-components urethane based adhesive composition.

COMPARATIVE EXAMPLE 1

(59) A battery module was identically manufactured with that of the Example 2 except an adhesive composition was not used, that is, did not form a resin layer.

(60) Materials properties of the resin layers and reliabilities of the battery modules from the above examples and comparative examples were measured, summarized, and input in table 1 below.

(61) TABLE-US-00001 TABLE 1 Comparative Examples example 1 2 3 4 5 6 7 1 Resin Thermal 3 3 3.5 3 1.5 1.5 2 — layer conductivity (W/mK) Specific 3.1 3.1 3.2 3.2 2 2 2.6 — gravity Residue at >80 >80 >80 >80 about about about — 800° C. 60 60 50 (weight %) Adhesion 500 100 450 600 80 90 500 — strength (gf/10mm) hardness 90 60 90 100 40 40 70 — (shore A) Insulation 15 11 10 <8 2 5 4 — breakdown voltage (kV/mm) Reliability good good good fair fair fair fair poor (withstand voltage) Reliability (thermal good good good fair fair fair fair poor resistance)

(62) It is apparent from the result of table 1 that materials properties of a resin layer are influenced by the type and ratio of resin used for the resin layer, and accordingly reliability of a module is also influenced.

(63) For example, it is apparent from a comparison between Examples 1, 2, and 4 that when alumina is added to obtain the same level of thermal conductivity, adhesion strength is higher in the order of an epoxy base resin layer, an urethane based resin layer, and a silicone based resin layer, hardness is higher in the order of an epoxy based resin layer, an urethane based resin layer, and a silicone based resin layer, and specific gravities and TGA results of thermal resistance were adjusted to a similar level. It is apparent that hardness in the case of Example 4 is slightly higher than those of Examples 1 and 2, and, accordingly, reliability result is slightly lowered.

(64) In addition, in is apparent from a comparison among Examples 2, 5, and 6 or among Examples 1, 3, and 7 that when the same material based resins are used, thermal conductivity, specific gravity, TGA result for thermal resistance, hardness, and the like were changed according to the type and amount of a filler. For example, in the case of Example 7, by applying an amount of filler less than those of the cases of Examples 1 and 3, values of thermal conductivity and specific gravity were slightly low, TGA result for thermal resistance was also slightly lower, although adhesion strength was at a similar level, hardness was slightly lowered, and particularly, an insulation breakdown voltage was lowered due to lowering of a ratio of the filler that influenced obtaining insulation properties. Accordingly, it is apparent that reliability evaluation result of Example 7 is slightly lower than those of Examples 1 and 3.