CN114094251A

CN114094251A - Battery pack and manufacturing method thereof

Info

Publication number: CN114094251A
Application number: CN202010631670.9A
Authority: CN
Inventors: 王良均; 邓春英; 马睿飞
Original assignee: Positec Power Tools Suzhou Co Ltd
Current assignee: Positec Power Tools Suzhou Co Ltd
Priority date: 2020-07-03
Filing date: 2020-07-03
Publication date: 2022-02-25

Abstract

The invention discloses a battery pack and a manufacturing method thereof, wherein the battery pack comprises: the battery module comprises a plurality of battery cores, and the battery cores are electrically connected with each other; an adapter for establishing mechanical and electrical connection between a power tool and the battery pack; the support is internally provided with a plurality of accommodating cavities, and each battery core is at least partially received in the accommodating cavity; the filler wraps up in the outside of every electric core and is located the inboard in chamber holds for outside the heat transfer that produces electric core holds the chamber, the filler along electric core lengthwise direction's length with the setting proportion of electric core length is not less than 30%. According to the battery pack and the manufacturing method thereof, the heat generated by the discharge of the battery core can be effectively transferred by optimizing the heat dissipation structure of the battery core, so that the discharge capacity of the battery core is increased, and the service time and the service life of the battery pack are prolonged.

Description

Battery pack and manufacturing method thereof

Technical Field

The invention relates to the technical field of electric tools, in particular to a battery pack and a manufacturing method thereof.

Background

The battery pack is generally a battery module formed by connecting a plurality of battery cells in series or in parallel. Furthermore, a plurality of battery modules can also form a battery core group with certain voltage and capacity in a series connection and parallel connection mode. The electric core in the battery package can produce the heat at the discharge in-process, and if these heats can not in time distribute, can influence the normal use of battery package, weaken the discharge capacity of battery package, shorten the life-span of battery package, can cause the incident even.

For the battery pack, it is required to have good heat dissipation performance. In the prior art, one way is to use air for heat dissipation. Specifically, a large airflow flowing gap is formed between the battery core and the support, and a negative pressure air duct communicated with the gap is arranged in the battery pack. However, the above heat dissipation manner for the battery core not only increases the volume of the battery pack, but also is not favorable for water resistance of the battery pack.

In addition, another mode in the prior art is to arrange a heat absorption material outside the battery cell for heat dissipation. Specifically, the periphery of the battery cell is provided with a heat absorbing material, and parts such as a plastic envelope backing plate and the like are required to be additionally arranged to carry out sealing assembly on the heat absorbing material. The mode is complex in structure on the whole and high in process cost.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention provides the battery pack and the manufacturing method thereof, and the heat generated by the discharge of the battery cell can be effectively transferred by optimizing the heat dissipation structure of the battery cell, so that the discharge capacity of the battery cell is increased, and the service time and the service life of the battery pack are prolonged.

The above object of the present invention can be achieved by the following technical solutions:

a battery pack, comprising: the battery module comprises a plurality of battery cores, and the battery cores are electrically connected with each other; an adapter for establishing mechanical and electrical connection between a power tool and the battery pack; the support is internally provided with a plurality of accommodating cavities, and each battery core is at least partially received in the accommodating cavity; the filler wraps up in the outside of every electric core and is located the inboard in chamber holds for outside the heat transfer that produces electric core holds the chamber, the filler along the length of electric core lengthwise direction with the setting proportion of electric core length is not less than 30%.

Further, the setting ratio of the setting length of the filler along the lengthwise direction of the battery cell to the length of the battery cell is not less than 50%.

Furthermore, the support is arranged in an integral manner, and the accommodating cavities are enclosed by the inner wall of the support and are independent of each other.

Further, the support includes first sub-support and second sub-support, hold the chamber including set up in a plurality of first chambeies that hold of first sub-support, and set up in a plurality of seconds of second sub-support hold the chamber, first chamber and the second of holding holds the chamber and is used for acceping at least part electric core respectively, works as when first sub-support and second sub-support dock in opposite directions, first chamber and the second of holding hold the chamber one-to-one.

Further, when the first sub-support and the second sub-support are oppositely butted, the first accommodating cavity and the second accommodating cavity are mutually communicated and can wrap the battery cell along the lengthwise direction of the battery cell without a gap.

Further, when the first sub-support and the second sub-support are oppositely butted, a gap is reserved between the first accommodating cavity and the second accommodating cavity along the lengthwise direction of the battery cell, and the outer side surface part of the battery cell is exposed from the gap.

Furthermore, the battery cell is provided with a lengthways extending body, and a positive pole section and a negative pole section are distributed at two ends of the body along the lengthways direction; the filler is arranged in a gap between the negative pole section and the accommodating cavity.

Further, the material of the filler comprises heat conduction glue, the heat conduction coefficient of the heat conduction glue is between 1 and 3, and the thickness of one side of the heat conduction glue is between 0 and 0.5 mm.

Further, the filler comprises a phase-change material which is in a solid state at normal temperature, and the phase-change material changes the form from the solid state to the liquid state or maintains the solid state in the heat absorption process.

Furthermore, the melting range of the phase-change material is between 40 ℃ and 70 ℃.

Furthermore, the inner wall of the accommodating cavity is convexly provided with a plurality of positioning pieces extending to the battery core, and the positioning pieces are abutted against the outer side surface of the battery core.

Further, the setting element is along electric core longitudinal extension, forms the mounting groove between the adjacent setting element, the filler set up in the mounting groove.

Further, the filler comprises at least 2 different phase-change materials, the melting ranges of the phase-change materials are at least partially different, and different phase-change materials are arranged in the adjacent mounting grooves.

A method for manufacturing a battery pack as described above, wherein for a case where the filler is in a solid state, the method comprises:

assembling the filler with one of the battery core and the bracket in a preset mode to form a first assembly body;

and assembling the first assembly body with the other one of the battery core and the bracket to form a second assembly body.

According to the battery pack and the manufacturing method thereof, the heat dissipation structure of the battery core is optimized, the gap between the battery core and the support is filled with the filler, and heat generated by discharging of the battery core can be effectively transferred, so that the discharge capacity of the battery core is increased, and the service life of the battery pack is prolonged.

Drawings

The invention is further described with reference to the following figures and embodiments.

Fig. 1 is an exploded view of a battery pack provided in an embodiment of the present application;

fig. 2 is a longitudinal cross-sectional view of a cell, a filler, and a single housing cavity in a bracket according to an embodiment of the present disclosure;

fig. 3 is a transverse cross-sectional view a-a of a single housing cavity in the cell, filler and holder provided in fig. 2;

FIG. 4 is a schematic illustration of a single receiving chamber in a stent provided in one embodiment of the present application;

fig. 5 is a schematic structural diagram of a cell, a filler and a single accommodating cavity in a bracket according to another embodiment of the present disclosure;

FIG. 6 is a transverse cross-sectional view of a single containment chamber in the stent provided with filler as provided in FIG. 5;

FIG. 7 is a longitudinal cross-sectional view of a single containment chamber of the stent provided with filler as provided in FIG. 5;

FIG. 8 is a longitudinal cross-sectional view of a single containment chamber of the alternative stent provided with filler as provided in FIG. 5;

fig. 9 is a longitudinal cross-sectional view of a cell, a filler, and a single containment chamber in a support provided in accordance with yet another embodiment of the present application;

fig. 10 is an exploded view of a battery pack provided in another embodiment of the present application;

fig. 11 is a longitudinal cross-sectional view of a single receiving cavity in a holder provided with a filler provided with the battery pack of fig. 10;

fig. 12 is a schematic diagram comparing cell temperature rise curves;

fig. 13 is a flowchart illustrating steps of a method for manufacturing a battery cell according to an embodiment of the present disclosure.

Description of reference numerals:

1. an electric core; 11. connecting sheets;

2. a support; 20. an accommodating chamber; 21. a first sub-mount; 22. a second sub-mount; 220. a limiting step; 23. a positioning member; 24. mounting grooves; 241. a first mounting groove; 242. a second mounting groove;

3. a filler; 31. a first thermally conductive adhesive; 32. a second thermally conductive adhesive;

41. an upper cover; 42. a lower cover;

5. a circuit board;

6. a seal member;

26. an open end; 27. a first limiting part; 28. a second limiting part.

Detailed Description

The technical solutions of the present invention will be described in detail with reference to the accompanying drawings and specific embodiments, it should be understood that these embodiments are merely illustrative of the present invention and are not intended to limit the scope of the present invention, and various equivalent modifications of the present invention by those skilled in the art after reading the present invention fall within the scope of the appended claims.

It will be understood that when an element is referred to as being "disposed on" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and the like as used herein are for illustrative purposes only and do not denote a unique embodiment.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the description of the present application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

The air is a bottleneck for preventing the heat transfer of the battery cell, the air can be reduced by reducing the thickness of the interface, the thermal resistance is reduced, and the air still exists more or less because the roughness of the interface is limited by the process and the assembly process of the battery cell.

This application is optimized through the heat radiation structure to electric core, utilizes the filler to fill the clearance between electric core and the support, can transmit out the heat that electric core discharge produced effectively to increase electric core discharge capacity, extension battery package live time and life.

Referring to fig. 1 to 9 or fig. 10 to 11 in combination, in an embodiment of the present disclosure, a battery pack is provided, where the battery pack mainly includes: the battery pack comprises a battery core 1, a bracket 2, filler 3 filled between the battery core 1 and the bracket 2, a circuit board 5, an adapting part for establishing mechanical and electrical connection between the battery pack and the electric tool, and other necessary electrical and mechanical connection mechanisms. The battery pack may further include a housing, the bracket 2 may be located in the housing, and in addition, the bracket 2 may be partially or wholly used as the housing, which is not specifically limited herein.

As shown in fig. 1 or fig. 10, in the present embodiment, the housing may include an upper cover 41 and a lower cover 42 that are coupled to each other. When the upper cover 41 and the lower cover 42 are butted, a relatively closed cavity is formed for accommodating the battery cell 1, the bracket 2, the circuit board 5 and the like.

In this embodiment, the battery cell 1 may be a cylindrical shape, for example, a cylindrical shape, and of course, the shape of the battery cell 1 may also be adaptively adjusted according to actual needs, for example, the battery cell may be a rectangular parallelepiped, or an approximate rectangular parallelepiped, or even other special-shaped structures. The shape and configuration of the battery cell 1 are not specifically limited in this application. In this specification, the battery cell 1 is mainly used as a cylindrical shape for illustration, and the shapes of other battery cells 1 can be referred to the present application by analogy. Specifically, the battery cell 1 may include a body extending along the longitudinal direction, and the body has a positive section and a negative section distributed along the longitudinal direction.

The number of the battery cells 1 and the serial-parallel connection mode between the battery cells 1 may be adjusted according to the voltage of the battery cells 1 and different nominal voltages, which is not specifically limited herein. Specifically, the battery cells 1 may be connected in series or in parallel through the connecting pieces 11, or a combination of series connection and parallel connection. The number of the battery modules can be one or two or more.

In the present embodiment, the bracket 2 is mainly used for mounting the battery cell 1, and a plurality of accommodating cavities 20 for mounting the battery cell 1 are formed inside the bracket 2. Each cell 1 is at least partially received in a corresponding receiving cavity 20. Specifically, the battery cell 1 may be partially located in the accommodating cavity 20; alternatively, the battery cells 1 may all be located in the accommodating cavity 20.

In the present embodiment, a filler 3 is disposed on an outer side surface of each of the battery cells 1 and inside the accommodating cavity 20, and the filler 3 is used for transferring heat generated by the battery cells 1 to the outside of the accommodating cavity 20.

In general, in the case of a battery pack in which the battery cell 1 is assembled by the holder 2, there are more or less gaps between the battery cell 1 and the holder 2, which gaps are air before the filler 3 is not provided. Air has high thermal resistance and small thermal conductivity coefficient, about 0.023(W/m.k), which is a poor heat conductor.

In order to ensure that the heat of the battery cell 1 can be effectively conducted out after the filler 3 replaces air, parameters such as the heat conductivity coefficient and the filling length of the filler 3 can be reasonably set. From the above, it is known that the resistance of an object to heat flow conduction is proportional to the length of a conduction path, inversely proportional to the cross-sectional area to pass through, and inversely proportional to the thermal conductivity of a material.

In the present embodiment, the ratio of the arrangement length of the filler 3 along the longitudinal direction of the battery cell 1 to the length of the battery cell 1 may be not less than 30%. Further, the longer the length of the material, the greater the thermal resistance. In order to better ensure the heat exchange effect between the filler 3 and the battery cell 1, the setting length of the filler 3 may be increased appropriately. Specifically, the ratio of the arrangement length of the filler 3 along the longitudinal direction of the battery cell 1 to the length of the battery cell 1 is not less than 50%.

In some embodiments, as shown in fig. 10 and 11, the stent 2 may be a monolithic stent; alternatively, in other embodiments, as shown in fig. 2-9, the stent 2 may be a split stent.

As shown in fig. 2 or fig. 7, when the stent 2 is a split stent, the stent 2 may include a first sub-stent 21 and a second sub-stent 22. The accommodating cavity 20 may include a plurality of first accommodating cavities disposed in the first sub-bracket 21 and a plurality of second accommodating cavities disposed in the second sub-bracket 22, where the first accommodating cavities and the second accommodating cavities are respectively configured to accommodate at least part of the battery cells 1, and when the first sub-bracket 21 and the second sub-bracket 22 are oppositely butted, the first accommodating cavities and the second accommodating cavities are in one-to-one correspondence.

For the split type support, as shown in fig. 2 or fig. 7, when the first sub-support 21 and the second sub-support 22 are butted oppositely, the first accommodating cavity and the second accommodating cavity are communicated with each other and can wrap the battery cell 1 along the lengthwise direction of the battery cell 1 without a gap. Or, as shown in fig. 9, a gap is left between the first accommodating cavity and the second accommodating cavity along the longitudinal direction of the battery cell 1, and the outer side surface of the battery cell 1 is partially exposed from the gap.

The battery pack will be described in detail with reference to specific embodiments and application scenarios.

In one embodiment, the battery cell 1 has a body extending lengthwise, and a positive pole section and a negative pole section are distributed at two ends of the body of the battery cell 1 along the lengthwise direction; the filler 3 is arranged in the gap between the negative pole section and the accommodating cavity 20.

In the present embodiment, the length of the negative electrode segment is generally greater than the length of the positive electrode segment. Correspondingly, the depth of the accommodating cavity of the sub-bracket arranged outside the negative electrode end along the longitudinal direction of the battery cell 1 is greater than the depth of the accommodating cavity of the sub-bracket arranged outside the positive electrode section along the longitudinal direction of the battery cell 1. The accommodating cavities with different depths can be correspondingly arranged in the first sub-bracket 21 or the second sub-bracket 22 according to different connection modes of the battery cells 1. As shown in fig. 1, when the battery cells 1 are connected in series, first receiving cavities with different depths may be arranged at intervals in the first sub-bracket 21. Similarly, the second sub-racks 22 may have second receiving cavities arranged at intervals and having different depths.

The accommodating cavity with the longer depth in the first accommodating cavity or the second accommodating cavity can be wrapped outside the negative pole section through the first heat-conducting glue 31 with zero clearance. In addition, the accommodating cavity with the shorter depth in the first accommodating cavity or the second accommodating cavity can be wrapped outside the positive electrode section of the battery core 1 through the second heat-conducting glue 32 with zero clearance. The first heat conductive paste 31 and the second heat conductive paste 32 may be the same or different. The zero-gap package may mean that the inner wall of the support 2 (including the first accommodating cavity and the second accommodating cavity) and the outer wall of the battery cell 1 (including the negative pole segment and the positive pole segment) may be partially or completely attached, and the two have no air gap in the radial direction at the attachment position.

The above-mentioned embodiment of the first and second sub-mounts 21 and 2, in which the mounts 2 are configured to be butted, is particularly suitable for a scenario where the sizes of the positive pole section and the negative pole section of the battery cell 1 are different. Specifically, for some electricity core 1, its positive pole section is the bulge form in radial direction for the negative pole section, if put this positive pole section with heat-conducting glue, the heat-conducting glue spills over easily. For the battery cells 1, the negative electrode section can be inserted into the accommodating cavity of a certain sub-bracket with a longer depth, and then the positive electrode section is sleeved in the accommodating cavity of another sub-bracket with a shorter depth.

In addition, when the length of the negative pole section is much longer than that of the positive pole section, the heat conduction function of the positive pole section is relatively very limited, and in this case, the filler 3 between the positive pole section and the inner wall of the accommodating cavity 20 can be omitted. For example, when the length of the negative electrode segment is 3 times or more the length of the positive electrode segment, the filler 3 outside the positive electrode segment may be omitted. That is, the filler 3 may be provided only in the gap between the negative electrode segment and the inner wall of the housing chamber 20.

As shown in fig. 2, in some embodiments, the holder 2 may have a cylindrical wall that matches the basic shape of the battery cell 1. The battery cell 1 and the inner wall of the accommodating cavity 20 may be in clearance fit to form a predetermined clearance H, and certainly, the situations that the battery cell 1 and the accommodating cavity 20 are in transition fit and interference fit are not excluded. In particular, the shape of the receiving cavity 20 may substantially match the external shape of the battery cell 1. For example, when the battery cell 1 is cylindrical as a whole, the accommodating cavity 20 of the holder 2 may have a hollow cylindrical shape.

For the embodiment that the accommodating cavity 20 of the bracket 2 is matched with the battery cell 1, the filler 3 is solid, and the filler 3 is continuously distributed along the longitudinal direction of the battery cell 1, which is beneficial to uniform heat exchange between the two.

In other embodiments, for example, where the filler 3 is in a liquid state, the shape of the accommodating cavity 20 may or may not match the shape of the battery cell 1. In particular, the cross-section of the receiving cavity 20 may be any regular or irregular shape, and the application is not limited thereto.

In addition, as shown in fig. 9, the brackets 2 may be discontinuously distributed in the longitudinal direction of the battery cell 1. The shape and size of the accommodating cavity 20 may be adapted according to whether the filler 3 is filled between the bracket 2 and the battery cell 1, and the type of the filler 3, and the like, and the application is not limited in detail here.

In some embodiments, when heat generated by the battery cell 1 needs to be conducted out through the support 2 as soon as possible, the support 2 may be made of a heat conducting material, which can conduct heat on the battery cell 1 out in time. For example, in order to ensure that the support 2 has good thermal conductivity, the thermally conductive material may be selected from materials having high thermal conductivity.

As shown in fig. 2, in the present embodiment, the filler 3 is wrapped on the outer side surface of each battery cell 1 and located inside the accommodating cavity 20, so as to transfer heat generated by the battery cells 1 to the outside of the accommodating cavity 20. For example, when the predetermined gap between the outer side surface of the battery cell 1 and the inner side surface of the accommodating cavity 20 of the bracket 2 is H, the thickness of the filler 3 may be H. Specifically, the material of the filler 3 may include a thermally conductive glue or a phase change material. Depending on the specific form of the material of the filler 3, the way in which the heat of the cell 1 is transferred varies. When the material of the filler 3 is a heat-conducting glue, the filler 3 serves as an intermediate medium for conducting heat of the battery cell 1 out to the support 2. When the material of the filler 3 is a phase-change material, the filler 3 serves as a heat-absorbing medium for absorbing heat generated by the battery cell 1.

In some embodiments, when the material of the filler 3 is in the form of a thermal conductive adhesive, the thermal conductive adhesive may be disposed between the support 2 and the battery cell 1 through any one of a back adhesive, a glue storage groove disposed on the support 2, and a secondary injection molding. Specifically, the heat-conducting adhesive can be arranged in different ways according to different providing forms. For example, for a solid planar thermally conductive gum sheet: the battery core can be bonded with the back glue on the periphery of the battery core 1 and then is arranged in the cylinder wall of the bracket 2 in an interference manner; the liquid adhesive may be pressed together to the predetermined gap H when the battery cell 1 is assembled, or when the predetermined gap H is 0, a space for accommodating the liquid adhesive may be formed by providing a glue storage groove on the holder 2. In addition, the secondary injection molding mode is a process of molding a certain plastic raw material in a primary plastic mold, taking out the molded part, putting the molded part into a secondary molding mold, and injecting the same or another plastic material again, and is the same as the encapsulation process of soft rubber.

In the present embodiment, the thermal conductive paste has a high thermal conductivity. In particular, the thermal conductivity may be between 1 and 3. When the material of the filler 3 is a heat conductive adhesive, the most core function of the filler 3 is to exhaust air in a predetermined gap H formed between the battery cells 1 and the filler. The thickness of the heat-conducting glue on one side is the same as the preset gap H. For example, when the predetermined gap is set to be greater than 0 and less than 0.5 mm, the one-sided thickness of the thermally conductive paste is also between 0 and 0.5 mm. It should be noted that the predetermined gap H is theoretically half of the difference between the aperture of the accommodating cavity 20 of the bracket 2 and the outer diameter of the battery cell 1, but in actual installation, the single-side gap may have a certain deviation, which may be greater than 0.5 mm, in consideration of installation errors.

In one embodiment, the battery cell 1 may include a body extending along a longitudinal direction, and the body has a positive section and a negative section distributed along the longitudinal direction. The gap formed between the battery cell 1 body and the bracket 2 may include a first gap between the negative pole segment and the bracket 2; at least the first gap is provided with the filler 3.

In the present embodiment, the battery cell 1 may be divided into a negative electrode segment and a positive electrode segment in the longitudinal direction thereof. The negative pole section is one section of battery cell comprising a negative pole, and the positive pole section is the other section of battery cell comprising a positive pole. Generally, the negative pole section is a cylindrical section with a regular shape and a smaller diameter, and the radial dimension of the positive pole section is larger than that of the negative pole section. At this time, the filler 3 may be provided only in the first gap between the negative electrode segment and the holder 2.

In one embodiment, the inner wall of the accommodating cavity 20 is convexly provided with a plurality of positioning members 23 extending towards the battery cell 1. This setting element 23 and electric core 1 lateral surface looks butt for to electric core 1's circumference location.

In this embodiment, the bracket 2 may further be provided with a positioning element 23 to position the battery cell 1, and the positioning element 23 may reliably ensure the stability of positioning the battery cell 1. As shown in fig. 3 and 4, the positioning element 23 may be a plurality of local rigid rib plates disposed at the end of the bracket 2, and the local rigid rib plates may be uniformly distributed along the circumferential direction. For example, 4 local rigid rib plates may be uniformly arranged along the circumferential direction, and when the battery cell 1 is installed in the bracket 2, the circumferential direction of the battery cell 1 abuts against the local rigid rib plates, so that circumferential positioning is achieved. Of course, the specific form of the positioning element 23 may be a hard material protruding portion, such as a plastic protruding portion, which is the same as the material of the bracket 2. Circumferential abutting can be achieved between the positioning piece 23 and the battery core 1, so that the battery core 1 is reliably circumferentially positioned. Of course, the specific form, material, etc. of the positioning member 23 are not limited to the above examples in the present specification, and those skilled in the art can make adjustment for adaptation, and the present application is not limited to the specific form herein.

Referring to fig. 5, 6 and 7, in other embodiments, the material of the filler 3 may include a phase change material that is solid at normal temperature. Wherein the normal temperature is generally 25 ℃.

In these embodiments, the phase change material having a thermal conductivity of about 1(W/m.k) and a high heat absorption capacity is filled in the predetermined gap H between the battery cell 1 and the support 2, so that heat discharged from the battery cell 1 can be effectively absorbed. Specifically, as shown in fig. 8, the phase change material changes its form from solid to liquid in an endothermic process; alternatively, as shown in fig. 9, the phase change material maintains a solid state during the heat absorption process.

In particular, the melting range may be at least partially different for the same phase change material. The melting range of the phase-change material is between 40 and 70 ℃.

In the present embodiment, the phase change material itself and the melting range of the phase change material are optimized, whereby an ideal heat absorption effect can be achieved.

Specifically, the heat conduction of the material takes time, and the battery cell 1 instantly emits a large amount of heat when discharging with a large current. Tests show that: when a 18650 electric core 1 discharges at the working current of 30A at normal temperature, the outer surface temperature is about 1 minute from 60 ℃ to 75 ℃. If the temperature of the phase change is about 75 ℃ closer to the protection temperature of the battery cell 1, the heat absorption efficiency is very low, i.e., the heat emitted by the large-current discharge of the battery cell 1 cannot be absorbed in time.

In addition, the comprehensive reference outdoor working environment temperature is about 40 ℃, when phase change materials with at least partially different melting ranges are selected, one melting range can be close to the environment temperature, and the other melting range is lower than the protection temperature of the battery core 1. As shown in fig. 12, applicants have found that: the condition that at least 2 kinds of phase change materials with different melting ranges are provided is the condition that the phase change materials with single melting ranges are relatively provided, the temperature rise curve of the battery cell 1 is more gentle, the battery cell 1 can be delayed to reach the protection temperature, and the discharging time of the battery cell 1 can be effectively prolonged.

In the present embodiment, when the phase-change material is selected as the filler 3, the phase-change material changes its form from a solid to a liquid during heat absorption, or maintains a solid state.

In one embodiment, the phase change material is disposed between the battery cell 1 and the support 2 in a full-circle wrapping manner.

In this embodiment, the form of the full-circle wrapping may be specifically: the phase change material may be in a through ring shape in the circumferential direction, and is disposed between the battery cell 1 and the support 2 with zero gap. The form of the whole circle of wrapping can effectively ensure the contact area between the battery cell 1 and the phase-change material.

As shown in fig. 5 and 6, in one embodiment, the positioning members 23 extend along the longitudinal direction of the battery cell 1, mounting grooves 24 are formed between adjacent positioning members 23, and the filler 3 is disposed in the mounting grooves 24.

In the present embodiment, a positioning member 23 extending in a longitudinal direction is disposed on an inner wall of the support 2, and on one hand, the positioning member 23 can be used for circumferentially positioning the battery cell 1, and on the other hand, a plurality of spaced mounting grooves 24 are formed between two adjacent positioning members 23. After the positioning piece 23 is arranged on the bracket 2, the phase change material is divided into a plurality of independent heat absorption areas with fan-shaped cross sections, so that the stability of the phase change material structure can be improved, the fit degree of the phase change material and the battery cell 1 can be ensured, and the phase change material, particularly the brittle phase change material, is prevented from cracking and the like in the use process; on the other hand, the phase change materials with different melting ranges (melting range: melting point of the phase change material after the organic matter is mixed, the melting point is a temperature range, and the temperature range is called melting range) can be flexibly arranged in different mounting grooves 24, so that the heat absorption effect of the phase change materials is improved.

In one embodiment, the filler 3 may include at least 2 different phase change materials, the melting ranges of the phase change materials are at least partially different, and different phase change materials are disposed in adjacent mounting grooves 24.

In the present embodiment, the mounting groove 24 may include: a first mounting groove 241 and a second mounting groove 242. The melting ranges of the phase change materials in the first and

second installation grooves

241 and 242 are different.

The number of the first mounting grooves 241 may be plural, and the number of the second mounting grooves 242 may also be plural. For example, in the figure, the number of the first mounting grooves 241 and the second mounting grooves 242 is 3, respectively. This first mounting groove 241 and second mounting groove 242 can be along the circumferencial direction interval distribution of this electricity core 1, and the journey of melting in this first mounting groove 241 and the second mounting groove 242 is different, can improve heat absorption efficiency to improve phase change material's heat absorption effect, realize the effective control to electric core 1 temperature rise.

As shown in fig. 8 or fig. 7, in the case that the phase-change material changes from a solid state to a liquid state during heat absorption, the battery cell 1 and the bracket 2 cooperate to form a sealed cavity for installing the phase-change material.

As shown in fig. 7, both ends of the phase change material in the longitudinal direction may be sealed by press-fitting between the end of the holder 2 and the electric core 1, so as to prevent the liquid phase change material from flowing out from the end faces where the two are fitted when the phase change material is converted into a liquid state or a solid-liquid mixed state.

Specifically, a sealed cavity can be formed between the battery cell 1 and the support 2 under the action of an axial compression force. The phase-change material is arranged in the sealing cavity to realize sealing. As shown in fig. 7, the phase change material is distributed in a negative pole section with a smaller diameter, the negative pole section corresponds to the first sub-mount 21, the positive pole section corresponds to the second sub-mount 2, and the inner diameter of the second sub-mount 2 is smaller than the inner diameter of the first sub-mount 21, so that a limit step 220 is formed at the butt joint position of the first sub-mount 21 and the second sub-mount 2. The thickness of the sealed cavity in which the phase change material is installed is the height of the limit step 220. The sealed cavity can be formed by matching the inner wall of the first sub-bracket 21, the outer wall of the battery cell 1 and the limiting step 220.

In addition, in order to further secure the reliability of the sealing, as shown in fig. 8, a sealing member 6 may be provided at least one end portion of the phase change material. The seal 6 may be embodied in the form of an elastic sealing gasket, the radial width of which may be slightly larger than the predetermined gap, so as to effectively seal the phase change material.

As shown in fig. 8, a circumferential position-limiting member for circumferentially positioning the battery cell 1 may be further formed at a position on the holder 2 near the end portion. The circumferential limiting member may be a first limiting portion 27 formed on the side of the holder 2 near the open end 26. Specifically, the first position-limiting portion 27 can refer to the positioning element 23, and the description of the present application is omitted. Of course, the first limiting portion 27 may also be in other forms capable of circumferentially limiting the battery cell 1, and the application is not limited in particular herein. The bracket 2 may be formed with a second position-limiting portion 28 at a position away from the open end 26, where the second position-limiting portion 28 is used for axially positioning the electric core 1. Specifically, the second position-limiting portion 28 may be a baffle plate disposed at an end of the bracket 2.

When the filler 3 is a phase-change material, the support 2 may refer to the specific description of the embodiment in which the filler 3 is a thermal conductive adhesive, and the detailed description is omitted here. For example, when the first sub-mount 21 is much longer than the second sub-mount 2, the phase change material in the second sub-mount 2 may also be omitted.

As shown in fig. 10 and 11, in the case where the phase change material maintains a solid state during heat absorption, the sealing property of the phase change material to convert into a liquid state does not need to be considered, and in this case, the structure of the bracket 2 can be further simplified. The bracket 2 is an integral bracket, and the accommodating cavities 20 are enclosed by the inner wall of the bracket 2 and are independent.

Specifically, the support 2 may be a hollow cylinder, one end of the cylinder is set as an open end 26, and the other end of the cylinder is provided with a second limiting portion 28 for limiting the axial direction of the battery cell 1. Specifically, the second limiting portion 28 may be a baffle at the end of the support 2, or may be in the form of a limiting step formed inside the support 2, so as to limit the axial direction of the battery cell 1. During assembly, the phase change material and the battery cell 1 can be mounted in the barrel body until the phase change material and the battery cell 1 abut against the second limiting part 28, and therefore mounting is achieved.

Referring to fig. 13, based on the battery pack provided in the foregoing embodiment, the present application further provides a method for manufacturing a battery pack, where the filler 3 is in a solid state, the method includes:

step S11: assembling the filler 3 and one of the battery core 1 and the bracket 2 in a preset mode to form a first assembly body;

step S13: and assembling the first assembly body with the other one of the battery core 1 and the bracket 2 to form a second assembly body.

In the present embodiment, the case that the filler 3 is in a solid state is mainly described, and the manufacturing method of the battery pack mainly includes assembling the filler 3 and one of the battery cell 1 and the bracket 2 by one of injection molding, assembly, adhesive application, and the like to form a first assembly. The first assembly is subsequently assembled with the remaining parts to form a second assembly. Finally, the plurality of second assemblies are electrically connected and are placed in the case to form the battery pack.

When the structure of the support 2 and the specific arrangement of the sealing member 6 are different, the manufacturing method of the battery cell 1 has certain differences.

The following description will be given by taking as an example that the holder 2 includes a first sub-holder 21 and a second sub-holder 22. During specific manufacturing, the filler 3 may be first installed in the first sub-mount 21 to form a first assembly; subsequently, the electrical core 1 is inserted into the first assembly; part of the battery cell 1 is exposed out of the first sub-mount 21. Then, the second sub-mount 22 provided with the sealing member 6 is sleeved outside the exposed battery cell 1 to form a second assembly body. And subsequently, electrically connecting the plurality of second assemblies, and putting the second assemblies into the shell to form the battery pack.

On the whole, the manufacturing method of the battery pack is simple in process, low in manufacturing cost and high in reliability, and is beneficial to improving the performance of the battery pack and reducing the cost of the battery pack.

In addition, in the case that the filler 3 is in a liquid state, the manufacturing method may form the filler 3 between the battery cell 1 and the support 2 mainly by injecting, painting, or the like. Specifically, the manufacturing method may include: assembling the battery core 1 and the bracket 2 to form a space for filling the filler 3; a filler 3 in liquid form is injected into the space formed. Subsequently, the plurality of assemblies are electrically connected and placed into the case to form the battery pack.

It should be noted that, in the description of the present application, the terms "first", "second", and the like are used for descriptive purposes only and for distinguishing similar objects, and no precedence between the two is intended or should be construed to indicate or imply relative importance. In addition, in the description of the present application, "a plurality" means two or more unless otherwise specified.

The above embodiments in the present specification are all described in a progressive manner, and the same and similar parts among the embodiments may be referred to each other, and each embodiment is described with emphasis on being different from other embodiments.

The above description is only a few embodiments of the present invention, and although the embodiments of the present invention are described above, the above description is only for the convenience of understanding the present invention, and is not intended to limit the present invention. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims

1. A battery pack, comprising:

the battery module comprises a plurality of battery cores, and the battery cores are electrically connected with each other;

an adapter for establishing mechanical and electrical connection between a power tool and the battery pack;

the support is internally provided with a plurality of accommodating cavities, and each battery core is at least partially received in the corresponding accommodating cavity;

the filler wraps up the lateral surface of every electric core and is located the inboard in chamber holds for outside the heat transfer that produces electric core holds the chamber, the filler along the length of setting up of electric core lengthwise direction with the proportion of electric core length is not less than 30%.

2. The battery pack of claim 1, wherein a ratio of a disposition length of the filler along a lengthwise direction of the battery cell to a disposition length of the battery cell is not less than 50%.

3. The battery pack of claim 1, wherein the frame is integrally formed, and the receiving cavities are defined by inner walls of the frame and are independent of each other.

4. The battery pack according to claim 1, wherein the holder includes a first sub-holder and a second sub-holder, the accommodating cavities include a plurality of first accommodating cavities provided in the first sub-holder and a plurality of second accommodating cavities provided in the second sub-holder, the first accommodating cavities and the second accommodating cavities are respectively configured to accommodate at least a portion of the battery cells, and when the first sub-holder and the second sub-holder are butted in opposite directions, the first accommodating cavities correspond to the second accommodating cavities one to one.

5. The battery pack of claim 4, wherein when the first sub-bracket and the second sub-bracket are butted in opposite directions, the first accommodating cavity and the second accommodating cavity are communicated with each other and can wrap the battery cell without a gap along the lengthwise direction of the battery cell.

6. The battery pack of claim 4, wherein when the first sub-bracket and the second sub-bracket are butted in opposite directions, a gap is formed between the first accommodating cavity and the second accommodating cavity along the longitudinal direction of the battery cell, and a part of the outer side surface of the battery cell is exposed from the gap.

7. The battery pack of claim 1, wherein the battery cell has a body extending lengthwise, and a positive section and a negative section are distributed at two ends of the body along the lengthwise direction; the filler is arranged in a gap between the negative pole section and the accommodating cavity.

8. The battery pack of claim 1, wherein the filler material comprises a thermally conductive paste having a thermal conductivity of between 1 and 3, and a single-sided thickness of between 0 and 0.5 mm.

9. The battery pack according to claim 1, wherein the filler includes a phase change material that is solid at normal temperature, and the phase change material changes its form from a solid to a liquid or maintains a solid state during an endothermic process.

10. The battery pack of claim 9, wherein the phase change material has a melting range between 40 ℃ and 70 ℃.

11. The battery pack of claim 1, wherein a plurality of positioning members extending toward the battery core are convexly disposed on an inner wall of the accommodating cavity, and the positioning members abut against an outer side surface of the battery core.

12. The battery pack of claim 11, wherein the positioning members extend longitudinally along the battery cells, mounting grooves are formed between adjacent positioning members, and the filler is disposed in the mounting grooves.

13. The battery pack of claim 12, wherein the filler comprises at least 2 different phase change materials, the phase change materials have at least partially different melting ranges, and different phase change materials are disposed in adjacent mounting grooves.

14. A method for manufacturing a battery pack according to claim 1, wherein the method for manufacturing the battery pack includes, for a case where the filler is in a solid state: