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EP-4492542-B1 - CYLINDRICAL LITHIUM BATTERY CAP SEALING STRUCTURE WITH BUILT-IN BMS BOARD

EP4492542B1EP 4492542 B1EP4492542 B1EP 4492542B1EP-4492542-B1

Inventors

  • ZENG, JINHUI
  • YANG, Dexin
  • LIU, Qiangen
  • LIU, HAIYAN

Dates

Publication Date
20260506
Application Date
20240520

Claims (5)

  1. A cylindrical lithium battery cap sealing structure with a built-in BMS board, characterized by comprising a steel housing (1), an outer surface of a side of the steel housing (1) being fixedly connected to a bottom housing (10), and a top surface of the bottom housing (10) being fixedly provided with a battery roll core (11), and the battery roll core (11) being adapted to the steel housing (1); and further comprising: a cap mechanism (2), an outer surface of a side of the cap mechanism (2) being fixedly connected to a connecting housing (12), and an outer surface of a side of the connecting housing (12) being integrally connected to an outer surface of a side of the steel housing (1); the cap mechanism (2) comprises a plastic bracket (20), an outer surface of a side of the plastic bracket (20) and an inner surface of a side of the connecting housing (12) being slidably arranged.
  2. The cylindrical lithium battery cap sealing structure with a built-in BMS board of claim 1, characterized in that a positive aluminum plate (21) is detachably installed on the inner bottom surface of the plastic bracket (20), and a mainboard (22) is placed on the top surface of the positive aluminum plate (21).
  3. The cylindrical lithium battery cap sealing structure with a built-in BMS board of claim 2, characterized in that a negative hardware ring (23) is placed on the top surface of the mainboard (22), an outer surface of a side of the negative hardware ring (23) and an inner surface of a side of the plastic bracket (20) are engaged with each other, and the negative hardware ring (23) is adapted to both the positive aluminum plate (21) and the mainboard (22).
  4. The cylindrical lithium battery cap sealing structure with a built-in BMS board of claim 3, characterized in that a positive plastic cover (24) is detachably installed on an outer surface of a side of the mainboard (22), and an outer surface of a side of the positive plastic cover (24) and an inner surface of a side of the negative hardware ring (23) are engaged with each other.
  5. The cylindrical lithium battery cap sealing structure with a built-in BMS board of claim 4, characterized in that the positive aluminum plate (21), the mainboard (22), the negative hardware ring (23) and the positive plastic cover (24) are all located inside the plastic bracket (20).

Description

Technical Field The invention relates to the technical field of lithium batteries, and in particular, to a cylindrical lithium battery cap sealing structure with a built-in BMS board. Prior art documents CN 112 448 046 and WO 2019/140924 disclose cylindrical battery cells. Background Art Compared with lead-acid batteries and lead storage batteries, lithium batteries have the advantages of small size, high energy density, high power, long life, small self-discharge, suitable temperature with wide range, stable discharge, etc., so they are widely used in various fields. The moisture content in the lithium battery plays a vital role in the performance of the lithium battery. When the lithium battery contains water, it will promote the decomposition of LiPF6 in the electrolyte and form HF gas, causing the internal pressure of the battery to increase and deformation, or even burst; in addition, the capacity of lithium batteries decreases with the increase of moisture. Excessive moisture in the lithium battery will also cause the internal resistance of the battery to increase. In severe cases, it may even cause the lithium battery to be unable to charge and discharge normally, and cannot store chemical energy. In order to ensure the safety and performance stability of lithium batteries, their sealing structure is very important. Existing cylindrical lithium batteries utilize a safety diaphragm arranged on the cap to prevent the lithium battery from deforming. When the internal pressure of the lithium battery is too large, the air pressure acts on the safety diaphragm, causing the V-shaped part of the safety diaphragm to deform, the internal volume of the lithium battery increases, and the air pressure decreases. In addition, in order to control the moisture content in the lithium battery, the lithium battery is produced in a drying room. However, existing cylindrical lithium batteries do not have a BMS protection board inside, nor do they have a sealing waterproof structure corresponding to the BMS protection board. External moisture can still enter the inside of the lithium battery, causing the capacity of the lithium battery to decrease and the internal resistance to increase. Therefore, a cylindrical lithium battery cap sealing structure with a built-in BMS board is proposed in order to solve the problems raised above. Summary of the Invention The purpose of the invention is to provide a cylindrical lithium battery cap sealing structure with a built-in BMS board to solve the problem that the cylindrical lithium battery cap currently on the market proposed by the above background does not have a BMS protection board and does not have a corresponding sealing waterproof structure of the BMS protection board, which will allow external moisture to still enter the inside of the lithium battery, causing the problem of reduced lithium battery capacity and increased internal resistance. In order to achieve the above purpose, the invention provides the following technical solutions: a cylindrical lithium battery cap sealing structure with a built-in BMS board, including a steel housing, wherein an outer surface of a side of the steel housing is fixedly connected to a bottom housing, and the top surface of the bottom housing is fixedly provided with a battery roll core adapted to the steel housing; and also including: a cap mechanism, wherein an outer surface of a side of the cap mechanism is fixedly connected to a connecting housing, and an outer surface of a side of the connecting housing is integrally connected to an outer surface of a side of the steel housing. The cap mechanism includes a plastic bracket, and an outer surface of a side of the plastic bracket and an inner surface of a side of the connecting housing are slidably arranged. By adopting the above technical solution, the mainboard can be easily and stably installed through the plastic bracket. Preferably, a positive aluminum plate is detachably installed on the inner bottom surface of the plastic bracket, and a mainboard is placed on the top surface of the positive aluminum plate. By adopting the above technical solution, the battery can be easily protected through the mainboard, thereby improving the service life of the battery. Preferably, a negative hardware ring is placed on the top surface of the mainboard, an outer surface of a side of the negative hardware ring and an inner surface of a side of the plastic bracket are engaged with each other, and the negative hardware ring is adapted to both the positive aluminum plate and the mainboard. By adopting the above technical solution, when the battery is connected to external electrical components through the positive aluminum plate and the negative hardware ring, stable discharge can be achieved. Preferably, a positive plastic cover is detachably installed on an outer surface of a side of the mainboard, and an outer surface of a side of the positive plastic cover and an inner surface of a side of the ne