A high expansion battery with a piston structure

Abstract

This invention discloses a high-expansion battery pack with an ultra-light piston structure, comprising a piston battery module, a cylinder, and a battery pack casing. The piston battery module and the cylinder are disposed inside the battery pack casing. The piston battery module includes an array of individual battery cells and a piston. A first end of the individual battery cell array is fixedly connected to the piston, and a second end of the individual battery cell array is fixedly connected to the battery pack casing. The cylinder is fixedly connected to the battery pack casing. The cylinder has a cavity for accommodating the piston. The expansion and contraction of the individual battery cell array drives the piston to reciprocate within the cavity. The cavity limits the piston, ensuring that the reciprocating motion of the piston is a linear motion along the expansion and contraction direction of the individual battery cell array. This invention achieves the technical effect of stable external dimensions during the charging and discharging process of the battery pack, effectively avoiding damage to the casing caused by the expansion and contraction of the battery module.

Description

Technical Field

[0001] This invention belongs to the field of battery pack technology, specifically relating to a high-expansion battery pack with a piston structure, and particularly to a lithium metal secondary battery pack with a piston structure. Background Technology

[0002] In recent years, the rapid development of drone technology has placed increasingly higher demands on the energy of storage batteries. However, the resulting increase in battery weight has severely limited the application of batteries in drone models. With the gradual maturation of lithium metal rechargeable battery technology, these batteries can achieve charge-discharge cycles within a certain timeframe, and their specific energy can reach over 530Wh / kg, making them highly valuable in high-energy-density applications. However, lithium metal rechargeable batteries lack the space for lithium-ion intercalation compared to traditional graphite anode materials. Therefore, significant volume expansion occurs during charging, especially in square soft-pack lithium metal batteries, where the thickness expansion is typically over 8%. During charging and discharging, the battery array size undergoes substantial contraction and expansion. Conventional methods of bonding and fixing individual cells or mechanically securing the battery module cannot prevent this. Otherwise, the relative displacement between the individual cells and the battery pack casing during expansion and contraction can lead to damage to the aluminum-plastic film on individual cells, expansion damage to mechanically fixed positions, and even structural damage to the battery pack casing due to expansion. When applied to drones, if the battery module expands too much, the mounting position and battery casing structure will be damaged, and the vibration will damage the battery module, ultimately causing the drone to fail to supply power. Summary of the Invention

[0003] The purpose of this invention is to overcome the above-mentioned defects and provide a high-expansion battery pack with an ultra-light piston structure. This invention solves the technical problem that the expansion and contraction of existing lithium metal battery modules damages the outer casing, and further solves the technical problem that existing lithium metal battery modules are difficult to lighten. This invention can achieve the technical effect of stable external dimensions of the battery pack during charging and discharging, and effectively avoids the damage to the outer casing caused by the expansion and contraction of the battery module.

[0004] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0005] The battery module inside the lithium metal secondary battery pack of the present invention can automatically adapt its size during the thickness expansion and contraction of the lithium metal secondary battery during the charging and discharging process, and completely fix the battery module in a three-dimensional square shape. This solves the problem that the internal battery module of the lithium metal secondary battery pack for UAVs cannot be effectively installed and fixed during flight, resulting in poor vibration resistance and damage to the battery pack shell caused by charging and discharging expansion.

[0006] A high-expansion battery pack with a piston structure includes a piston battery module, a cylinder, and a battery pack casing;

[0007] The piston battery module and cylinder are located inside the battery pack casing;

[0008] The piston battery module includes an array of individual battery cells and a piston; the first end of the individual battery cell array is fixedly connected to the piston, and the second end of the individual battery cell array is fixedly connected to the battery pack casing.

[0009] The cylinder is fixedly connected to the battery pack casing; the cylinder is provided with a cavity for accommodating the piston. The expansion and contraction of the individual battery array drives the piston to reciprocate in the cavity. The cavity limits the piston, so that the reciprocating motion of the piston is a linear motion along the expansion and contraction direction of the individual battery array.

[0010] Furthermore, the pistons in the cylinder and piston battery module are made of foam material.

[0011] Furthermore, the foam material is a high-strength foam plastic with a strength of 5~20MPa;

[0012] The high-strength foam plastic includes PVC, PMI, PP, PE or EPS.

[0013] Furthermore, the single-cell array includes several ordered single-cell cells, each of which is a lithium metal secondary battery cell.

[0014] The piston battery module also includes clamps and binding wires;

[0015] Two clamps are respectively located at both ends of the single cell array along the expansion and contraction direction; binding wire is wrapped around the outside of the single cell array and the clamps to tighten the clamps at both ends of the single cell array to fix the shape of the single cell array.

[0016] The plywood is made of carbon fiber material;

[0017] The binding thread is made of aramid fiber material.

[0018] Furthermore, the first and second ends of the single-cell array are located at opposite ends along the expansion and contraction direction of the single-cell array.

[0019] The second end of the single cell array and the cylinder are located on both sides of the battery pack casing along the expansion and contraction direction of the single cell array, respectively.

[0020] The first end of the single cell array is bonded to the piston.

[0021] Furthermore, the dimensions of the cylinder cavity in each of the three dimensions are 0.2 to 0.5 mm smaller than those of the piston in each of the three dimensions.

[0022] The end face of the piston that extends into the cylinder can be either regular or irregular in shape.

[0023] Furthermore, a cut-off area is provided on the lower edge of the piston end that extends into the cylinder, and the cut-off area is used to guide the piston during the process of entering the cylinder.

[0024] Furthermore, the bottom of the individual cell array in the piston battery module contacts the bottom of the battery pack casing. When the individual cell array expands and contracts, relative sliding occurs between the bottom of the individual cell array and the bottom of the battery pack casing.

[0025] Furthermore, a bottom heating strip is attached to the upper surface of the bottom of the battery pack casing. The contact surface between the bottom of the individual battery array in the piston battery module and the bottom heating strip is lubricated with a lubricant. When the individual battery array expands and contracts, relative sliding occurs between the bottom of the individual battery array and the bottom heating strip.

[0026] The first end of the single-cell array is also equipped with an end heating strip.

[0027] Furthermore, the number of piston battery modules is ≥1;

[0028] The number of cavities in the cylinder is equal to the number of pistons in the piston battery module, and the cavities correspond one-to-one with the pistons.

[0029] Compared with the prior art, the present invention has at least one of the following advantages:

[0030] (1) This invention creatively proposes a high-expansion battery pack with a piston structure, which solves the key problems such as the large expansion and contraction of the battery cell thickness during the use of lithium metal secondary battery modules, which makes it impossible to install the lithium metal battery modules and causes damage to the installation structure or battery pack shell. It also pioneers a method suitable for installing and fixing lithium metal battery modules, achieving the technical effect of stable external dimensions of the battery pack during the charging and discharging process.

[0031] (2) The lithium metal battery module of the present invention can achieve complete fixation of the three-dimensional structure under expansion and contraction conditions, and has the best adaptability to the lithium metal battery pack used in the flight vibration process of the UAV, thus achieving the technical effect of reliable fixation of the charging, discharging, contraction and expansion structure of the battery pack during flight vibration.

[0032] (3) The present invention adopts a foam piston structure. The foam piston and foam cylinder are made of high-strength foam plastic with a strength of 5~20MPa, which has the advantages of high strength and light weight compared with conventional metal or rubber elastic materials.

[0033] (4) The present invention adopts a piston structure design. The foam piston will expand into the foam cylinder along with the battery array of the lithium metal battery module, providing extra space for the battery array and defining the expansion direction of the battery array, effectively preventing the battery pack shell from deforming during the expansion and contraction of the lithium metal battery module.

[0034] (5) The present invention can flexibly adjust the number of individual battery arrays in the battery pack. The change in the number of battery arrays does not affect the fixing effect of the present invention on the battery pack and the limiting effect on deformation.

[0035] (6) The present invention has finely designed the cut-off area and size of the piston, which is beneficial to improving the stability of the piston and cylinder cooperation. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of the high-expansion battery pack structure of the present invention;

[0037] Figure 2 This is a schematic diagram of a typical arrangement of the single-cell battery array of the present invention;

[0038] Figure 3 This is a schematic diagram of the cylinder block structure of the present invention.

[0039] Figure 4 This is a schematic diagram of the piston dimensions of the present invention, wherein (a) is a front view and (b) is a side view;

[0040] Figure 5 This is a schematic diagram of the dimensions of the foam cylinder of the present invention, wherein (a) is a front view and (b) is a side view;

[0041] In the diagram, 1-piston battery module, 2-cylinder, 3-battery pack casing, 101-single cell, 102-clamping plate, 103-piston, 104-binding wire, 105-bottom heating band, 106-end heating band, 201-cylinder body, 202-cylinder cavity. Detailed Implementation

[0042] The features and advantages of the present invention will become clearer and more apparent from the following detailed description.

[0043] The term “exemplary” as used herein means “serving as an example, embodiment, or illustration.” Any embodiment illustrated herein as “exemplary” is not necessarily to be construed as superior to or better than other embodiments. Although various aspects of embodiments are shown in the accompanying drawings, the drawings are not necessarily drawn to scale unless specifically indicated otherwise.

[0044] This invention solves the problems of difficult installation, heavy weight, damage to the outer shell, and inability to adapt to the vibration of drone flight by installing a foam piston on the lithium metal battery module to form a piston constraint.

[0045] The present invention provides a high-expansion battery pack with a piston structure, comprising a piston battery module 1, a cylinder 2, and a battery pack casing 3.

[0046] The piston battery module 1 includes a single cell array and a piston. The single cell array is an array formed by several single cells being clamped by clamps. One end of the array is directly or indirectly fixed to the battery pack shell 3, and the other end of the array is fitted with a piston. The piston is partially inserted into the cavity of the cylinder 2. During the charging and discharging process of the battery, it expands and contracts, and the piston reciprocates inside the cylinder 2.

[0047] The bottom and top of the piston battery module 1 are not fixedly connected to the battery pack housing 3. They are only directly or indirectly fixed to one side of the battery pack housing 3 at one end of the individual cell array. There is no fixed connection between the module and the other sides of the battery pack housing 3. The bottom of the individual cell array is in contact with the bottom of the battery pack housing, allowing relative sliding. When a bottom heating strip 105 is present, it is adhered and fixed to the upper surface of the bottom of the housing 3. The upper surface of the bottom heating strip 105 is in contact with the bottom of the individual cell array, allowing relative sliding. Thermally conductive silicone grease is used to conduct heat and lubricate the bottom of the entire individual cell array.

[0048] Both the piston and cylinder 2 are made of foam material, and the cavity structure dimensions of the cylinder are matched with the outer shape structure dimensions of the piston.

[0049] The cavity docking shape of the piston and cylinder 2 can be various, including circular, square, triangular, plum blossom-shaped or other irregular shapes. Alternatively, the position can be interchanged, that is, the cylinder 2 is connected to the single cell array and reciprocates with the expansion and contraction of the single cell array, while the piston is fixed on the battery pack housing 3.

[0050] The single cell is a lithium metal secondary battery cell.

[0051] Piston battery module 1 includes:

[0052] Individual cells are arranged in an orderly manner to form a battery array; clamps are placed at both ends of the battery array; binding wires or straps are used to tighten the clamps at both ends to fix the battery array; pistons are attached to the outer end face of one side of the clamp.

[0053] The binding thread is made of aramid fiber.

[0054] The cylinder 2 includes: a cavity for accommodating the piston and allowing the piston to slide; and a cylinder body that is directly or indirectly fixed to the battery pack housing 3.

[0055] The plywood is made of lightweight, high-strength material, preferably carbon fiber.

[0056] The piston and cylinder 2 are made of high-strength foam plastic with a strength of 5~20MPa, and the materials selected are PVC, PMI, EPS, etc.

[0057] This invention primarily addresses the problems of poor vibration resistance and damage to the battery pack casing caused by the inability to effectively install and secure the internal battery modules during flight in UAV lithium metal secondary battery packs. By employing a piston and cylinder structure, automatic dimensional adaptation is achieved during the thickness expansion and contraction of the lithium metal secondary battery during charging and discharging. This solves problems such as significant deformation of the battery pack casing due to the volume expansion of the lithium metal battery, and vibrations during transportation and use caused by the inability to effectively secure the battery pack due to excessive expansion during charging and discharging. The piston and cylinder are made of foam material, minimizing their weight and playing a crucial role in the lightweight design of UAVs.

[0058] Example:

[0059] like Figure 1 As shown, the high-expansion battery pack provided in this embodiment includes: a piston battery module 1, a cylinder 2, and a battery pack casing 3. The high-expansion battery pack of the present invention can accommodate multiple piston battery modules 1. By restricting the expansion direction of the lithium metal secondary battery through the piston structure, it avoids deformation of the piston battery module while greatly saving the internal space of the high-expansion battery pack, and can give full play to the high specific energy advantage of the lithium metal secondary battery.

[0060] like Figure 2 As shown, the piston battery module 1 includes: a single-cell array composed of individual cells 101, clamping plates 102 on both sides of the single-cell array, a piston 103 fixed to one side of the clamping plate, and binding wires 104 for tightening the clamping plates on both sides. When a heating design is required to adapt to low-temperature environments, the piston battery module 1 also includes a bottom heating band 105 and an end heating band 106.

[0061] To address the expansion rate issue of lithium metal secondary batteries, individual battery cells 101 are arranged sequentially to form a battery array. Clamping plates 102 are positioned on the outside of the battery array, and binding wires 104 tighten the clamping plates 102 at both ends, making the battery array a complete unit and clamping it securely. One end of the battery assembly is directly or indirectly fixed to the battery pack casing 3, while the other end is bonded with a piston 103 made of foam material. The other free end of the piston 103 is placed inside the cylinder cavity 202. The cylinder body 201 of the cylinder 2 is directly or indirectly and completely fixed to the inside of the battery pack casing 3. The foam piston and foam cylinder are made of closed-cell foam plastic with good elasticity and resilience, such as polyethylene foam or polypropylene foam, with polypropylene foam being preferred. A fully fixed bottom heating strip 105 is attached to the upper bottom surface of the battery pack casing 3. The bottom heating strip matches the dimensions of the battery stack (when not expanded) in the expansion direction. The bottom of the piston battery module 1 is in contact with the bottom heating strip on the battery pack casing 3, and the piston battery module 1 is allowed to slide. The contact surface is lubricated with a high-viscosity lubricant. Thus, the combined array consisting of the clamping plate 102, the binding wire 104, and the individual battery cell 101 can only move along the route specified at the bottom.

[0062] To address the issue of battery pack operation in low-temperature environments, further heating measures are required. A bottom heating band 105 is installed at the bottom of the piston battery module 1. The bottom heating band is adhered and fixed to the battery pack casing 3. The piston battery module 1 is in contact with the bottom heating band and is allowed to move. The gap between the two is filled with thermally conductive silicone grease for heat conduction and lubrication. Since the heating range of the bottom heating band 105 is limited, when the piston battery module expands, the individual cells at the movable end exceed the heating range, and the bottom cannot be effectively heated. An end heating band 106 is installed at the movable end. The end heating band 106 heats the piston battery module after it expands beyond the heating area of ​​the bottom heating band, thus solving the problem of the bottom not being effectively heated due to the end extending beyond the heating area after expansion.

[0063] like Figure 3 As shown, the cylinder 2 includes: a cylinder body 201 that is directly or indirectly fixed to the battery pack housing 3, and a cylinder cavity 202 for accommodating the piston 103.

[0064] The piston battery module 1 is subject to multi-dimensional constraints and fixation, exhibiting excellent resistance to mechanical environments. One end of the piston battery module 1 is completely fixed to the battery pack casing 3, while the other end is inserted into the cylinder cavity 202 via a piston 103, preventing the piston 103 end of the piston battery module 1 from wobbling. The piston-like structure formed by the piston 103 and the cylinder 2 provides the space required for its expansion, thus protecting the casing structure and preventing it from being squeezed and burst.

[0065] The lithium metal secondary battery described in this invention refers to a rechargeable lithium metal secondary battery with a lithium metal negative electrode. The thickness of this lithium metal battery in its fully charged state can be more than 8% greater than its thickness in the discharged state.

[0066] like Figure 4 This is a schematic diagram of the dimensions of piston 103. The piston has a width of a1, a height of b1, and a thickness of c1. The portion of the piston that is placed into the cylinder cavity 202 of the cylinder body 2 has a cut-off area. The cut-off area is actually a bevel formed by cutting off a triangular portion from the lower edge of the piston. The cut-off area allows piston 103 to be easily installed inside the cylinder cavity 202. After installation, it should also be located inside the cylinder cavity 202 during normal operation when the battery is not expanding.

[0067] like Figure 5 The diagram shows the dimensions of cylinder 2. The cylinder cavity 202 has a width of A1, a height of B1, and a thickness of C1. Dimension A1 is matched with and slightly smaller than dimension a1, and dimension B1 is matched with and slightly smaller than dimension b1, with a difference of 0.2mm to 0.5mm. Dimension C1 is matched with and slightly larger than dimension c1. The thickness direction corresponds to the expansion and contraction direction.

[0068] In summary, this invention employs an aramid wire tensioning clamp to hold the lithium metal secondary battery and a piston-type structure, which can address the need for lightweight battery module design. Simultaneously, the combination of the battery pack shell, bottom, foam piston, and foam cylinder completely restricts the expansion direction of the lithium metal secondary battery module, significantly reducing the volumetric weight of high-expansion battery packs. This represents a significant improvement in weight reduction compared to existing lithium metal secondary battery pack technologies, and also meets the requirements for the charge and discharge characteristics of lithium metal secondary batteries.

[0069] The present invention has been described in detail above with reference to specific embodiments and exemplary examples; however, these descriptions should not be construed as limiting the present invention. Those skilled in the art will understand that various equivalent substitutions, modifications, or improvements can be made to the technical solutions and embodiments of the present invention without departing from the spirit and scope of the invention, and all such modifications and improvements fall within the scope of the present invention. The scope of protection of the present invention is defined by the appended claims.

[0070] The contents not described in detail in this specification are common knowledge to those skilled in the art.

Claims

1. A high-expansion battery pack with a piston structure, characterized in that, Includes piston battery module (1), cylinder (2) and battery pack casing (3); The piston battery module (1) and the cylinder (2) are located inside the battery pack casing (3); The piston battery module (1) includes a single cell array and a piston; the first end of the single cell array is fixedly connected to the piston, and the second end of the single cell array is fixedly connected to the battery pack casing (3); The cylinder (2) is fixedly connected to the battery pack housing (3); the cylinder (2) is provided with a cavity for accommodating the piston. The expansion and contraction of the single battery array drives the piston to reciprocate in the cavity. The cavity limits the piston, so that the reciprocating motion of the piston is a linear motion along the expansion and contraction direction of the single battery array. The cavity provided in the cylinder (2) allows the piston to slide; The piston in the cylinder (2) and piston battery module (1) is made of foam material; The foam material is a high-strength foam plastic with a strength of 5~20MPa; The high-strength foam plastic includes PVC, PMI, PP, PE or EPS.

2. The high-expansion battery pack with a piston structure according to claim 1, characterized in that, The single-cell array consists of several ordered single cells, which are lithium metal secondary battery cells. The piston battery module (1) also includes a clamping plate and binding wires; Two clamps are respectively located at both ends of the single cell array along the expansion and contraction direction; binding wire is wrapped around the outside of the single cell array and the clamps to tighten the clamps at both ends of the single cell array to fix the shape of the single cell array. The plywood is made of carbon fiber material; The binding thread is made of aramid fiber material.

3. A high-expansion battery pack with a piston structure according to claim 1, characterized in that, The first and second ends of the single-cell array are located along the expansion and contraction direction of the single-cell array. The second end of the single cell array and the cylinder (2) are located on both sides of the battery pack casing (3) along the expansion and contraction direction of the single cell array, respectively; The first end of the single cell array is bonded to the piston.

4. A high-expansion battery pack with a piston structure according to claim 1, characterized in that, The dimensions of the cylinder (2) in the three-dimensional direction are 0.2~0.5mm smaller than the dimensions of the piston in the three-dimensional direction; The end face of the piston extending into the cylinder (2) has a regular or irregular shape.

5. A high-expansion battery pack with a piston structure according to claim 1, characterized in that, The lower edge of the piston extending into the cylinder (2) is provided with a cut-off area, which is used to guide the piston during the process of the piston entering the cylinder (2).

6. A high-expansion battery pack with a piston structure according to claim 1, characterized in that, The bottom of the individual cell array in the piston battery module (1) contacts the bottom of the battery pack casing (3). When the individual cell array expands and contracts, relative sliding occurs between the bottom of the individual cell array and the bottom of the battery pack casing (3).

7. A high-expansion battery pack with a piston structure according to claim 1, characterized in that, A bottom heating strip (105) is attached to the upper surface of the bottom of the battery pack casing (3). The contact surface between the bottom of the individual battery array in the piston battery module (1) and the bottom heating strip (105) is lubricated with lubricant. When the individual battery array expands and contracts, relative sliding occurs between the bottom of the individual battery array and the bottom heating strip (105). The first end of the single cell array is also provided with an end heating band (106).

8. A high-expansion battery pack with a piston structure according to claim 1, characterized in that, The number of piston battery modules (1) is ≥1; The number of cavities in the cylinder (2) is equal to the number of pistons in the piston battery module (1), and the cavities correspond one-to-one with the pistons.

Images