Patent Application
20220285761
The present disclosure relates to battery manufacturing technology, and in particular to a liquid cooling battery module for combining cells.
Compared with diesel buses, electric buses are confronted with limitations in terms of convenience of public transport. For example, electric buses are disadvantaged by short driving range, long charging time, and short battery service life. Furthermore, battery modules account for an extremely large proportion of the cost of electric buses, and thus cost efficiency of electric buses depends on the service life of battery modules. To increase the popularity of electric buses, the current trend of development of electric buses is to develop fast charging technology and heat management technology in hopes that battery modules of electric buses will not only be recharged quickly but will also enjoy long service life.
Fast charging is associated with selection of types of cells. Long service life is associated with battery management and heat management. In the course of recharging and discharging, the increase in temperature caused by ohmic heat and chemical reaction heat in lithium-ion battery not only directly affects the cells' service life, efficiency, reliability and safety, but battery heat becomes out of control as a result of accumulation and poor management of heat. Research findings are as follows: the optimal operating temperature of lithium-ion battery ranges from 20° C. to 45° C.; and the maximum temperature difference between the cells or between modules must not be greater than 5° C. Therefore, it is necessary to provide an appropriate battery heat management system operating within a fast charging battery system.
Battery heat management systems are of three types: air cooling system, liquid cooling system, and PCM (phase change material) cooling system. The air cooling system is disadvantaged by poor cooling performance and thus fails to meet the battery cooling requirement in adverse environment or is unable to operate under heavily loaded cycling condition. The PCM-based cooling system is effective in lowering temperature and keeping the temperature difference small, but its application is restrained by the packaging and volume change during a phase change period. Therefore, liquid cooling is a better choice for the heat management system of electric vehicles, such as a battery system of an electric bus.
CN 205621819 discloses liquid cooling pipes functioning as the base of a prismatic battery, wherein underlying pipes of a larger diameter serve as the base which batteries lie on. Liquid cooling pipes of a smaller diameter are disposed between the batteries and thus space apart the batteries, respectively. The serpentine pipes is designed to increase contact area. However, the batteries are neither fastened to the liquid cooling system nor designed to come into contact therewith. Therefore, the odds are that poor heat dissipation battery might occur because of poor contact between the liquid cooling pipes.
U.S. Pat. No. 6,858,344 discloses a liquid cooling battery module, wherein a securing board 34 is produced from outside and adapted to press a battery and a cooling board inward to thereby for them to be attached firmly to each other. However, this design is likely to cause a problem: a fastening element 35 loosens because of a creep arising from a long time period of high temperature. As a result, the joint of the battery and the cooling board deteriorates gradually, leading to eventual deterioration of heat dissipation performance.
U.S. Pat. No. 6,858,344 disposes placing a metal heat dissipation board in between batteries and then placing a heat dissipation plastic pad in between the metal heat dissipation board and each battery to firmly attach them to each other. Then, the battery structure is placed on the liquid cooling board. Next, the metal heat dissipation board and the liquid cooling board are tightly joined, using the heat dissipation plastic pad. The liquid cooling pipe is not located between the batteries to achieve heat dissipation; instead, heat generated by the batteries is transferred by the metal heat dissipation board and heat dissipation plastic pad to the underlying liquid cooling board to attain heat dissipation. Excessive heat transfer interfaces are indicative of limited heat dissipation performance.
U.S. Pat. No. 9,923,251 discloses liquid cooling tubes adapted for cylindrical cells and adapted to work by contact heat dissipation. The liquid cooling tubes (209, 301) achieve heat dissipation by being in contact with the bottom surfaces of the cylindrical cells or the lateral surfaces of the cylindrical cells. Owing to the limitative effect of the geometrical shapes of the surfaces of the cylindrical cells, the liquid cooling tubes enclose the lateral surfaces of the cells. As a result, their contact area is disadvantageously confined to corners of the cylindrical surfaces or even only a straight line, not to mention limited contact surface area and poor heat dissipation performance.
An objective of the present disclosure is to provide a liquid cooling battery module, wherein multi-port extrusion tubes (MPET) function as heat dissipation tubes disposed between cells and adapted to dissipate heat by liquid cooling, so as to achieve battery module fast charging, control temperature, and attain uniform distribution of temperature quickly and effectively by liquid cooling.
To achieve at least the above objective, the present disclosure provides a liquid cooling battery module, comprising: a collector; a cell liquid cooler having a plurality of multi-port extrusion tubes spaced apart equidistantly and parallelly, the multi-port extrusion tubes each being connected to a first end of the collector, the collector being in communication with the multi-port extrusion tubes to thereby form a cooling liquid circulation space, wherein an adaptor is disposed at a second end of the collector, the second end being opposite the first end, the adaptor being in communication with the cooling liquid circulation space; a plurality of cells disposed between the multi-port extrusion tubes parallelly and alternately; a base disposed below the cell liquid cooler, wherein a plurality of cell positioning slots are disposed at a bottom of the base and adapted to contain the cells; an upper lid disposed above the cell liquid cooler; and a plurality of copper busbars disposed above the upper lid to electrically connect the cells in series and in parallel.
In an embodiment of the present disclosure, the cooling liquid circulating within the cooling liquid circulation space is deionized water, a mixture of deionized water and ethylene glycol (50%/50%), or a mixture of deionized water and propylene glycol (60%/40%).
In an embodiment of the present disclosure, the cells are prismatic or pouch cells.
In an embodiment of the present disclosure, the cells are spaced apart from the multi-port extrusion tubes by a distance, and the distance ranges from 0.3 to 1.0 mm.
In an embodiment of the present disclosure, the base has a plurality of support posts for preventing the upper lid from pressing against the cells and the multi-port extrusion tubes.
In an embodiment of the present disclosure, the upper lid has a plurality of thermal paste injection apertures whereby thermal paste is injected into the liquid cooling battery module.
In an embodiment of the present disclosure, the liquid cooling battery module is in a plural number and stacked up.
In an embodiment of the present disclosure, the liquid cooling battery module further comprises at least one diverting strip which connects the stacked liquid cooling battery modules to the adaptors, respectively.
In an embodiment of the present disclosure, the liquid cooling battery module further comprises a soft copper busbar for connecting the copper busbars of the stacked liquid cooling battery modules.
In an embodiment of the present disclosure, cross sections of the multi-port extrusion tubes are polygons and concave polygons.
To facilitate understanding of the object, characteristics and effects of this present disclosure, embodiments together with the attached drawings for the detailed description of the present disclosure are provided.
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In an embodiment of the present disclosure, to increase capacitance or voltage of the liquid cooling battery module 1 despite inadequate space on XZ-plane, two or more layers of the liquid cooling battery module 1 are stacked up in direction Y, and the upper and lower layers are not necessarily equal in the number of the cells.
The liquid cooling battery module 1 further comprises at least one diverting strip 6. The respective adaptors 13 for the upper and lower layers of the liquid cooling battery module 1 are connected by the at least one diverting strip 6. The diverting strip 6 serves as a cooling tube parallel-connection framework of the upper and lower layers of the liquid cooling battery module 1. The diverting strip 6 connects the cell liquid coolers 10 (cooling liquid circulation space) of the upper and lower layers of the liquid cooling battery module 1. After both their cooling liquids have met, the adaptors 13 output or input the cooling liquids which have undergone heat exchange.
Therefore, the present disclosure provides a liquid cooling battery module 1 comprising cells between which heat-dissipating tubes are disposed and adapted to control temperature and attain uniform distribution of temperature quickly and effectively by liquid cooling. The heat-dissipating tubes are multi-port extrusion tubes. The multi-port extrusion tubes are provided in the form of multi-port aluminum extrusion tubes. According to the present disclosure, the multi-port extrusion tubes are planar liquid cooling tubes suitable for use with prismatic LTO (lithium titanium oxide) cells or pouch cells. Furthermore, according to the present disclosure, the multi-port extrusion tubes are effective in dissipating heat when aligned with geometrically-shaped surfaces of the cells in a plane-to-plane manner without undergoing any bending process. Also, the present disclosure is advantageous in that the multi-port extrusion tubes can be applicable to prismatic cells of any dimensions by altering the spacing, length or width of the multi-port extrusion tubes, so as to meet the strict heat dissipation requirement of fast charging battery modules. Therefore, liquid cooling enables large battery modules of electric buses to not only be recharged quickly but also enjoy long service life.
In this embodiment, the cooling liquid circulating within the cooling liquid circulation space is deionized water, a mixture of deionized water and ethylene glycol (50%/50%), or a mixture of deionized water and propylene glycol (60%/40%).
In this embodiment, the cells 4 are prismatic or pouch cells.
While the present disclosure has been described by means of specific embodiments, numerous modifications and variations could be made thereto by those skilled in the art without departing from the scope and spirit of the present disclosure set forth in the claims.
