Liquid-cooled immersion type marine lithium iron phosphate battery pack

Abstract

This invention discloses a liquid-cooled, submersible marine lithium iron phosphate battery pack, comprising a battery box, battery modules, coolant, immersion fluid, and monitoring components. The battery box includes a box body, a support plate, and a box cover. The support plate is fixed inside the box body to divide the inner cavity of the box body into an immersion chamber and a cooling chamber from top to bottom. The box cover is bolted to the upper end face of the box body to close the box body. The battery modules include multiple battery cells. The multiple battery cells are fixed to the top surface of the support plate. Coolant fills the cooling chamber. Immersion fluid fills the immersion chamber and immerses the battery cells. The liquid level of the immersion fluid is higher than the top surface of the battery cells. The monitoring components are installed on the outer wall of the box body to collect the voltage, temperature, and over-temperature signals of the battery cells. This invention ensures the transfer of heat to the external environment after thermal runaway of the battery cells through a dual cooling mechanism of coolant and immersion fluid, effectively ensuring the absolute safety of the battery pack during use.

Description

Technical Field

[0001] This invention relates to the field of new energy technology, and more specifically to a liquid-cooled, submersible marine lithium iron phosphate battery pack. Background Technology

[0002] Currently, most marine batteries are liquid-cooled battery packs, which use liquid cooling channels to cool the batteries. When the battery cells generate heat, the heat is transferred to the metal of the liquid cooling plate through heat conduction on the upper surface and inside the liquid cooling plate. Then, the relative movement between the fluid inside the liquid cooling plate and the surface of the liquid cooling plate forces convection heat transfer, and the heat is carried away by the fluid movement, thus completing the battery's thermal management. At the same time, the existing design solutions for fire safety and thermal runaway mainly use heat-insulating and flame-retardant materials, such as aerogel pads filled between the cells. When a single cell experiences thermal runaway, the heat generated is blocked by the aerogel pads, which delays and weakens the impact of thermal runaway on surrounding cells. In addition, lithium iron phosphate cells have weaker chemical activity and reactivity than ternary lithium cells, which, in combination, can protect surrounding cells from being passively triggered by thermal runaway.

[0003] The safety of liquid-cooled batteries relies on the intrinsic safety performance of the cells themselves and the level of manufacturing technology. However, industrial production is not an ideal environment, so the safety of liquid-cooled marine batteries is relative. Current manufacturing processes make the batteries very safe to use, but not absolutely safe. Absolute safety is an impossible pursuit. Therefore, liquid-cooled batteries have the risk of thermal runaway. Although this risk is small, there are no direct and effective means to suppress or stop the continuation of thermal runaway after it occurs, so absolute safety cannot be achieved.

[0004] Therefore, how to provide a marine lithium iron phosphate battery with a higher safety factor is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] In view of this, the present invention provides a liquid-cooled immersion marine lithium iron phosphate battery pack, which ensures the transfer of heat to the external environment after thermal runaway of the battery cell through a dual cooling mechanism of coolant and immersion liquid, effectively ensuring the absolute safety of the battery pack during use.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A liquid-cooled, submersible marine lithium iron phosphate battery pack includes: A battery box, comprising a box body, a support plate, and a box cover; the support plate is fixed inside the box body to divide the inner cavity of the box body into an immersion chamber and a cooling chamber from top to bottom; the box cover is bolted to the upper end face of the box body to cover the box body. A battery module, the battery module comprising multiple battery cells; the multiple battery cells are fixed to the top surface of the support plate; Coolant, which fills the cooling chamber; An immersion liquid is used to fill the immersion cavity and immerse the battery cell; the level of the immersion liquid is higher than the top surface of the battery cell. A monitoring component is installed on the outer wall of the enclosure to collect the voltage, temperature, and over-temperature signals of the battery cells.

[0008] The beneficial effects of the technical solution of the present invention are that it uses coolant to achieve forced cooling of the battery cell, and at the same time uses immersion liquid to soak the battery cell to absorb the heat generated by thermal runaway of the battery cell. The heat absorbed by the immersion liquid is dissipated through heat exchange with the external environment through the side wall of the box, thus preventing the possibility of fire or explosion of the battery cell due to thermal runaway, and meeting the needs of high-rate use of battery packs.

[0009] Preferably, the housing has a coolant inlet and a coolant outlet at both ends of the side wall below the support plate. The coolant inlet and outlet are connected to the outlet and inlet of the cooling unit via pipes to allow the coolant to circulate within the cooling chamber. The cooling unit utilizes the circulating coolant within the cooling chamber to remove heat generated by the battery cells, achieving a forced cooling effect.

[0010] Preferably, multiple baffles are fixed between the inner bottom wall of the housing and the bottom surface of the support plate, and these baffles create a serpentine flow path for the coolant. This serpentine flow path significantly improves the cooling effect on the battery cells.

[0011] Preferably, the housing has an immersion liquid drain port on the upper side wall corresponding to the support plate. The immersion liquid is discharged through the immersion liquid drain port.

[0012] Preferably, the battery module further includes steel strips and a CCS integrated busbar; multiple battery cells are arranged in parallel and pressed together; there are multiple steel strips, which are annular and encircle the outer periphery of the multiple battery cells; the CCS integrated busbar is fixed to the top surface of the multiple battery cells and connects the multiple battery cells in series or parallel through wires; the CCS integrated busbar is fastened to the support plate by screws and is located below the surface of the immersion liquid; the bottom surfaces of the multiple battery cells are bonded to the top surface of the support plate by thermally conductive structural adhesive. Multiple battery cells are bound together into an integral structure using annular steel strips, and the multiple battery cells are connected in series or parallel through the CCS integrated busbar, which has the function of collecting battery cell voltage, temperature, and over-temperature signals; the bottom surfaces of the battery cells are bonded to the support plate with structural adhesive, and the upper ends are fastened to the support plate by the CCS integrated busbar and screws, achieving a stable installation of the battery module inside the housing.

[0013] Preferably, the top surface of the battery cell is provided with a pressure relief valve; the CCS integrated busbar has a through hole for the pressure relief valve to pass through; the opening of the pressure relief valve allows the immersion fluid to enter the battery cell. After the battery cell experiences thermal runaway and the internal pressure changes, the pressure relief valve will open when the internal pressure of the battery cell drops. At this time, the immersion fluid will enter the battery cell and wet the battery cell core, reducing the intensity of the thermal runaway reaction, blocking the possibility of fire or explosion caused by thermal runaway, and ensuring the absolute safety of the battery pack.

[0014] Preferably, the device further includes two end plates, which are respectively pressed against the two inner walls of the housing, and the multiple battery cells are clamped between the two end plates. The two end plates clamp the multiple battery cells, and the end plates can provide preload force and fix and support the multiple battery cells.

[0015] Preferably, a heat-insulating and vibration-damping pad is embedded between the two opposing surfaces of two adjacent battery cells; there are multiple battery modules, and adjacent battery modules are connected in series via copper busbars. The heat-insulating and vibration-damping pad can prevent heat exchange between adjacent battery cells and has a vibration-damping effect; by setting multiple battery modules, the performance of the battery pack can be improved.

[0016] Preferably, the monitoring component includes a battery BTU and a battery BMU fixed to the outer wall of the enclosure; the battery BTU is electrically connected to the battery cell to collect the over-temperature signal of the battery cell; the battery BMU is electrically connected to the battery cell to collect the voltage and temperature signals of the battery cell.

[0017] Preferably, it also includes a protective cover, which is bolted to the outer wall of the housing and fastens the battery BTU and the battery BMU; the outer surface of the protective cover is provided with a high voltage hazard sign and a battery pack nameplate; the bottom surface of the protective cover is provided with a BTU input interface, a BMU input interface, a BTU output interface and a BMU output interface.

[0018] As can be seen from the above technical solution, compared with the prior art, the present invention discloses a liquid-cooled immersion marine lithium iron phosphate battery pack. The dual cooling mechanism of coolant and immersion liquid ensures the transfer of heat to the external environment after thermal runaway of the battery cell. It has a large heat dissipation area and obvious temperature uniformity, effectively ensuring the absolute safety of the battery pack during use. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the battery pack structure provided by the present invention; Figure 2 This is an exploded view of the battery pack provided by the present invention; Figure 3 This is a schematic diagram of the battery module structure provided by the present invention; Figure 4 This is an exploded view of the battery module provided by the present invention; Figure 5 This is a schematic diagram of the coolant flow path provided by the present invention; Figure 6 The battery pack heat exchange distance diagram provided by the present invention; Figure 7 The cell valve port pressure curve provided by this invention.

[0021] The components are as follows: 1-Battery box; 11-Box body; 12-Box cover; 13-Explosion-proof valve; 14-Wire busbar; 15-Coolant inlet; 16-Coolant outlet; 17-Screw; 18-Support plate; 19-Immersion fluid drain port; 2-Battery module; 21-Battery cell; 22-End plate; 23-Steel strip; 24-CCS integrated busbar; 25-Heat insulation and shock absorption pad; 26-Pressure relief valve; 3-Monitoring component; 31-Battery BTU; 32-Battery BMU; 33-Protective cover; 34-BTU input interface; 35-BMU input interface; 36-BTU output interface; 37-BMU output interface; 38-Battery pack nameplate; 39-High voltage hazard sign; 4-Coolant; 5-Immersion fluid. Detailed Implementation

[0022] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] See appendix Figure 1 To be continued Figure 7To address the current situation where existing marine lithium iron phosphate batteries cannot achieve absolute safety during use, this invention discloses a liquid-cooled immersion marine lithium iron phosphate battery pack, including a battery box 1, battery modules 2, coolant 4, immersion liquid 5, and monitoring components 3. The battery box 1 includes a box body 11, a support plate 18, and a box cover 12. The support plate 18 is fixed inside the box body 11 to divide the inner cavity of the box body 11 into an immersion chamber and a cooling chamber from top to bottom. The box cover 12 is bolted to the upper end face of the box body 11 to cover the box body 11. The battery module 2 includes multiple battery cells 21. The multiple battery cells 21 are fixed to the top surface of the support plate 18. The coolant 4 fills the cooling chamber. The immersion liquid 5 fills the immersion chamber and immerses the battery cells 21. The liquid level of the immersion liquid 5 is higher than the top surface of the battery cells 21. The monitoring components 3 are installed on the outer wall of the box body 11 to collect the voltage, temperature, and over-temperature signals of the battery cells 21.

[0024] In this embodiment, the side wall of the housing 11 below the support plate 18 is provided with a coolant inlet 15 and a coolant outlet 16 at both ends. The coolant inlet 15 and the coolant outlet 16 are respectively connected to the outlet and inlet of the cooling unit through pipelines to allow the coolant 4 to circulate in the cooling chamber. The upper side wall of the housing 11 above the support plate 18 is provided with an immersion liquid drain port 19.

[0025] In this embodiment, the coolant circulates through a cooling unit, while the immersion liquid remains stationary within the immersion chamber of the enclosure. The circulating coolant carries away the heat generated by thermal runaway of the battery cells, achieving forced cooling. The heat absorbed by the coolant is dissipated through heat exchange with the external environment via the cooling unit. The immersion liquid absorbs the heat generated by thermal runaway and dissipates it through heat exchange with the external environment via the side walls of the enclosure. This embodiment utilizes the circulating coolant and the complete immersion of the battery cells by the immersion liquid to achieve heat dissipation for the battery pack, ensuring absolute safety during battery pack operation.

[0026] To further optimize the above technical solution, the coolant is a mixture of water and ethylene glycol, and the immersion liquid is a fluorinated liquid or insulating oil.

[0027] It should be noted that in this embodiment, the immersion fluid wets the outer periphery of each cell, meaning that heat dissipation on all five sides of the cell is achieved through the immersion fluid, which has a heat dissipation effect nine times that of conventional marine lithium iron phosphate batteries. Furthermore, the heat generated by thermal runaway of a single cell is insufficient to heat other cells and the surrounding immersion fluid to the point of thermal runaway. Simultaneously, the immersion fluid circulates at the bottom of the cell for forced cooling, ensuring the absolute safety of the cell.

[0028] To further optimize the above technical solution, multiple baffles are fixed between the inner bottom wall of the housing 11 and the bottom surface of the support plate 18. The multiple baffles make the coolant 4 form a serpentine flow path, which can improve the forced cooling effect of the coolant 4.

[0029] To further optimize the above technical solution, the battery module 2 also includes a steel strip 23 and a CCS integrated busbar 24; multiple battery cells 21 are arranged in parallel and pressed together; there are multiple steel strips 23, which are annular and wrapped around the outer periphery of multiple battery cells 21; the CCS integrated busbar 24 is fixed to the top surface of multiple battery cells 21 and the multiple battery cells 21 are connected in series or in parallel through wires; the CCS integrated busbar 24 is fastened to the support plate 18 by screws 17 and is located below the surface of the immersion liquid 5; the bottom surface of multiple battery cells 21 is bonded to the top surface of the support plate 18 by thermally conductive structural adhesive.

[0030] Multiple battery cells are bound together into a single structure by a ring-shaped steel band. The CCS integrated busbar is used to connect multiple battery cells in series or in parallel and to collect voltage, temperature and over-temperature signals. The bottom of the battery cells is bonded to the top of the support plate with thermally conductive structural adhesive. The battery module is installed by bolting it to the support plate with the CCS integrated busbar and screws.

[0031] To further optimize the above technical solution, a pressure relief valve 26 is provided on the top surface of the battery cell 21; a through hole for the pressure relief valve 26 to pass through is provided on the CCS integrated busbar 24; the pressure relief valve 26 can be opened to allow the immersion liquid 5 to enter the battery cell 21.

[0032] During thermal runaway in a conventional battery cell, the valve port pressure exhibits a changing curve comprising three stages: First, in the early stages of thermal runaway, the internal pressure of the cell rises slowly until it reaches the opening pressure of the pressure relief valve; then, after the pressure relief valve opens, the pressure rapidly reaches its peak, subsequently decreasing due to gas cooling and release, and the pressure relief port may close; finally, as thermal runaway continues, the pressure continues to increase or even intensify, and the temperature rises, potentially causing the valve port pressure to rise again. A typical pressure curve exhibits a bimodal characteristic, with the peak pressure related to battery design and electrolyte composition. Figure 7 As shown, in this embodiment, the battery cell is immersed in an immersion liquid. In the early development stage of thermal runaway, due to the high pressure at the valve port, the pressure relief valve is closed, and the immersion liquid cannot penetrate into the battery cell. In the second stage of valve port pressure development, the valve port pressure decreases, the pressure relief valve opens, and the immersion liquid can enter the battery cell, diluting and contaminating the electrolyte inside the battery cell, thus slowing down the intensity of the thermal runaway reaction. Furthermore, as the amount of immersion liquid entering increases, the degree of wetting inside the battery cell increases, and the intensity of thermal runaway decreases until the thermal runaway completely consumes the usable material inside the battery cell or the immersion liquid completely wets the battery cell core, at which point the thermal runaway reaction ends.

[0033] This embodiment utilizes a circulating cooling oil system for forced cooling. Immersing the battery cell in the immersion fluid serves two purposes: firstly, thermal management—the immersion fluid absorbs the heat generated during charging and discharging, and also distributes heat evenly, resulting in a smaller temperature difference compared to conventional self-cooled and liquid-cooled batteries; secondly, the immersion fluid absorbs the heat generated by thermal runaway reactions within the battery cell, and enters the cell during the second stage of pressure development at the cell valve, reducing the intensity of the thermal runaway reaction and preventing the possibility of fire or explosion. This ensures the absolute safety of the battery pack and avoids the risk of fire or explosion.

[0034] In other specific embodiments, two end plates 22 are also included. The two end plates 22 are respectively pressed against the two inner walls of the housing 11, and multiple battery cells 21 are clamped between the two end plates 22. The end plates 22 can provide preload to fix and support the multiple battery cells.

[0035] To further optimize the above technical solution, prevent heat exchange between two adjacent cells, and improve the shock absorption performance of the battery pack, a heat insulation and shock absorption pad 25 is embedded between the two opposing surfaces of two adjacent cells 21.

[0036] To further optimize the above technical solution and improve the performance of the battery pack, there are multiple battery modules 2, and adjacent battery modules 2 are connected in series through a copper busbar 14.

[0037] In some other specific embodiments, the cover 12 is provided with an explosion-proof valve 13.

[0038] The battery box is protected against explosions by an explosion-proof valve. When high-pressure gas is generated inside the battery box due to thermal runaway, overcharging, short circuit, or other reasons, the explosion-proof valve will rupture or open in a specific direction to release the pressure and prevent the battery box from exploding.

[0039] To further optimize the above technical solution, the monitoring component 3 includes a battery BTU31 and a battery BMU32 fixed to the outer wall of the housing 11; the battery BTU31 is electrically connected to the cell 21 to collect the over-temperature signal of the cell 21; the battery BMU32 is electrically connected to the cell 21 to collect the voltage and temperature signals of the cell 21.

[0040] To further optimize the above technical solution, a protective cover 33 is also included. The protective cover 33 is bolted to the outer wall of the housing 11 and fastens the battery BTU 31 and battery BMU 32. The outer surface of the protective cover 33 is provided with a high voltage danger sign 39 and a battery pack nameplate 38. The bottom surface of the protective cover 33 is provided with a BTU input interface 34, a BMU input interface 35, a BTU output interface 36 and a BMU output interface 37.

[0041] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to the method section.

[0042] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A liquid-cooled, submersible marine lithium iron phosphate battery pack, characterized in that, include: A battery box (1) includes a box body (11), a support plate (18), and a box cover (12); the support plate (18) is fixed inside the box body (11) to divide the inner cavity of the box body (11) into an immersion chamber and a cooling chamber from top to bottom; the box cover (12) is bolted to the upper end face of the box body (11) to cover the box body (11). The battery module (2) includes multiple battery cells (21); the multiple battery cells (21) are fixed to the top surface of the support plate (18); Coolant (4), the coolant (4) fills the cooling chamber; Immersion liquid (5) fills the immersion cavity and soaks the battery cell (21); the liquid level of the immersion liquid (5) is higher than the top surface of the battery cell (21); Monitoring component (3) is installed on the outer wall of the housing (11) to collect the voltage, temperature and over-temperature signal of the battery cell (21).

2. The liquid-cooled submersible marine lithium iron phosphate battery pack according to claim 1, characterized in that, The box (11) has a coolant inlet (15) and a coolant outlet (16) at both ends of the side wall below the support plate (18). The coolant inlet (15) and coolant outlet (16) are respectively connected to the outlet and inlet of the cooling unit through pipelines so that the coolant (4) circulates in the cooling chamber.

3. A liquid-cooled, submersible marine lithium iron phosphate battery pack according to claim 2, characterized in that, Multiple partitions are fixed between the inner bottom wall of the box (11) and the bottom surface of the support plate (18), and the multiple partitions cause the coolant (4) to form a serpentine flow path.

4. The liquid-cooled submersible marine lithium iron phosphate battery pack according to claim 1, characterized in that, The box (11) has an immersion liquid drain port (19) on the upper side wall corresponding to the support plate (18).

5. A liquid-cooled, submersible marine lithium iron phosphate battery pack according to claim 1, characterized in that, The battery module (2) also includes a steel strip (23) and a CCS integrated busbar (24); multiple battery cells (21) are arranged in parallel and pressed together; there are multiple steel strips (23), which are annular and wrapped around the outer periphery of multiple battery cells (21); the CCS integrated busbar (24) is fixed on the top surface of multiple battery cells (21) and connected in series or parallel with wires; the CCS integrated busbar (24) is fastened to the support plate (18) by screws (17) and is located below the surface of the immersion liquid (5); the bottom surface of multiple battery cells (21) is bonded to the top surface of the support plate (18) by thermally conductive structural adhesive.

6. A liquid-cooled, submersible marine lithium iron phosphate battery pack according to claim 5, characterized in that, The top surface of the battery cell (21) is provided with a pressure relief valve (26); the CCS integrated busbar (24) is provided with a through hole for the pressure relief valve (26) to pass through; the pressure relief valve (26) can be opened to allow the immersion liquid (5) to enter the battery cell (21).

7. A liquid-cooled, submersible marine lithium iron phosphate battery pack according to claim 5, characterized in that, It also includes two end plates (22), which are pressed against the two inner walls of the housing (11) respectively, and the multiple battery cells (21) are sandwiched between the two end plates (22).

8. A liquid-cooled, submersible marine lithium iron phosphate battery pack according to claim 7, characterized in that, A heat-insulating and shock-absorbing pad (25) is embedded between the two opposite surfaces of two adjacent battery cells (21); there are multiple battery modules (2), and two adjacent battery modules (2) are connected in series through a copper busbar (14).

9. A liquid-cooled, submersible marine lithium iron phosphate battery pack according to claim 1, characterized in that, The monitoring component (3) includes a battery BTU (31) and a battery BMU (32) fixed to the outer wall of the housing (11); the battery BTU (31) is electrically connected to the battery cell (21) to collect the over-temperature signal of the battery cell (21); the battery BMU (32) is electrically connected to the battery cell (21) to collect the voltage and temperature signals of the battery cell (21).

10. A liquid-cooled, submersible marine lithium iron phosphate battery pack according to claim 9, characterized in that, It also includes a protective cover (33), which is bolted to the outer wall of the housing (11) and fastens the battery BTU (31) and the battery BMU (32); the outer surface of the protective cover (33) is provided with a high voltage hazard sign (39) and a battery pack nameplate (38); the bottom surface of the protective cover (33) is provided with a BTU input interface (34), a BMU input interface (35), a BTU output interface (36) and a BMU output interface (37).

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