Battery cell composite structure

Abstract

The utility model discloses a battery cell composite structure, which comprises a battery cell and a swelling rod capable of swelling in a battery electrolyte environment, an open cavity is arranged in the battery cell, and the swelling rod is arranged in the open cavity. The battery cell composite structure is reasonable in design, the swelling rod is arranged in the cylindrical cell, the swelling rod can expand in an electrolyte environment, and the expanded swelling rod has certain elasticity and can resist inward extrusion caused by expansion of a silicon-carbon negative electrode; the problems of extrusion after expansion of the silicon-carbon negative electrode of the lithium battery and collapse of the battery cell can be solved.

Description

Technical Field

[0001] The utility model relates to the technical field of batteries, in particular to a battery core composite structure. Background Art

[0002] As new energy vehicles continue to increase their requirements for endurance, battery negative electrode materials are also developing towards high energy density. Although traditional graphite negative electrode materials have mature processes and low costs, their development in energy density has approached their theoretical maximum value (372mAh / g). Silicon has gradually come into people's attention due to its ultra-high gram capacity (4200mAh / g) and low lithium insertion potential (0.4V), but the significant volume expansion (~300%) of silicon negative electrodes during charging and discharging has greatly limited its large-scale commercialization process. The silicon particles in the negative electrode will undergo severe volume expansion during the lithium insertion process, which will cause the active material particles to break and pulverize, and destroy the existing SEI film on the particle surface. The exposed new silicon particle surface will further react with the electrolyte to form a new SEI film. The repeated rupture and regeneration of the SEI film will not only accumulate many side reaction products and cause the total volume of the battery cell to continue to expand, but will also easily cause the internal resistance and polarization of the battery cell to continue to increase, and ultimately aggravate the capacity decay of the battery cell; as the battery is charged and discharged, the silicon-carbon negative electrode of the battery cell will continue to expand, causing the expanded silicon-carbon negative electrode to squeeze into the internal pore cylinder of the battery, resulting in the collapse of the bare battery cell and other adverse phenomena.

[0003] For example, Chinese patent CN113381126A discloses a lithium battery separator for inhibiting the expansion of a silicon-carbon negative electrode and a hot pressing method for a lithium battery cell containing the separator. The lithium battery separator includes a polymer base film, an inorganic particle ceramic coating coated on both sides of the polymer base film, and an adhesive inorganic particle mixed coating coated on both sides of the inorganic particle ceramic coating; the hot pressing method includes: 1) hot pressing the battery cell once; 2) hot pressing the battery cell twice; 3) standing; 4) degassing; as the battery is charged and discharged, the silicon-carbon negative electrode of the battery cell continues to expand. Although this solution has a certain inhibitory effect, it cannot completely prevent the expanded silicon-carbon negative electrode from squeezing into the internal pore cylinder of the battery, resulting in undesirable phenomena such as the collapse of the bare battery cell. Utility Model Content

[0004] In view of the shortcomings of the existing technology, the utility model provides a battery cell composite structure to achieve the purpose of resisting the expansion and inward extrusion of the silicon-carbon negative electrode.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0006] The battery core composite structure comprises a battery core and a swelling rod capable of swelling in a battery electrolyte environment. An open cavity is provided in the battery core, and the swelling rod is arranged in the open cavity.

[0007] Further:

[0008] The battery core is a cylindrical battery core.

[0009] A swelling rod placement hole is provided at the axial center of the battery core, and the swelling rod placement hole forms a cavity.

[0010] The swelling rod placement hole is a through hole.

[0011] The swelling rod placement hole is a cylindrical hole.

[0012] An annular groove is provided on the swelling rod, and a protrusion matching the annular groove is provided in the cylindrical hole.

[0013] The swelling rod is a cylindrical rod with a diameter of 1-5 mm.

[0014] Compared with the prior art, the present invention has the following advantages:

[0015] The battery cell composite structure is reasonably designed. The swelling rod is arranged in the cylindrical cell. The swelling rod can expand in the electrolyte environment. The expanded swelling rod has a certain elasticity and can resist the inward extrusion of the silicon-carbon negative electrode due to expansion. It can solve the extrusion of the silicon-carbon negative electrode after expansion of the lithium battery and solve the problems of battery cell collapse. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The following is a brief description of the contents and symbols in the drawings of this specification:

[0017] Figure 1 This is a schematic diagram of the composite structure of the battery cell of the utility model.

[0018] In the picture:

[0019] 1. Cylindrical battery cell, 2. Swelling rod. DETAILED DESCRIPTION

[0020] The specific implementation of the present invention will be further explained in detail below through the description of embodiments with reference to the accompanying drawings.

[0021] like Figure 1 As shown, the battery cell composite structure includes a battery cell and a swelling rod 2 that can expand in a battery electrolyte environment. An open cavity is provided in the battery cell, and the swelling rod is arranged in the open cavity.

[0022] The swelling rod of the utility model is arranged in the cylindrical battery core 1. The swelling rod can expand in the electrolyte environment. The expanded swelling rod has a certain elasticity and can resist the inward squeezing of the silicon-carbon negative electrode due to expansion. It can solve the squeezing of the silicon-carbon negative electrode after expansion of the lithium battery and solve the problems of battery core collapse.

[0023] Preferably, the battery cell is a cylindrical battery cell, and a swelling rod placement hole is provided in the axial center of the battery cell, the swelling rod placement hole forms a cavity, and the swelling rod placement hole is a cylindrical hole; the swelling rod is a cylindrical rod, and the diameter of the swelling rod is 1-5 mm; the swelling rod is placed in the swelling rod placement hole.

[0024] The swelling rod placement hole is a through hole with openings at both ends; further, a groove is provided on the inner wall of the swelling rod placement hole along the axial direction, which can fully contact with the electrolyte to ensure the internal expansion effect.

[0025] An annular groove is provided on the swelling rod, and a protrusion matching the annular groove is provided in the cylindrical hole, so the structure is stable.

[0026] The swelling rod can be extruded using existing swelling materials; the raw materials are mixed evenly, melted and mixed evenly in a screw extruder, and then extruded into the required specifications, and then placed into the central pore of the battery cell after the battery cell is shelled, which is simple to manufacture and process.

[0027] The above is only an illustration of a preferred embodiment of the present invention. The above technical features can be arbitrarily combined to form multiple embodiments of the present invention.

[0028] The above is an exemplary description of the present invention in conjunction with the accompanying drawings. It is obvious that the specific implementation of the present invention is not limited to the above-mentioned method. As long as various non-substantial improvements are made using the concept and technical solution of the present invention, or the concept and technical solution of the present invention are directly applied to other occasions without improvement, they are all within the scope of protection of the present invention.

Claims

1. A battery cell composite structure, comprising a battery cell, characterized in that: It also includes a swelling rod that can expand in the battery electrolyte environment, the battery core is provided with an open cavity, and the swelling rod is arranged in the open cavity; A swelling rod placement hole is provided in the axial center of the battery cell, and the swelling rod placement hole forms a cavity; the swelling rod placement hole is a through hole; The inner wall of the hole for placing the swelling rod is provided with a groove along the axial direction, which can fully contact with the electrolyte; The swelling rod is provided with an annular groove, and the cylindrical hole is provided with a protrusion that matches the annular groove; the swelling rod is a cylindrical rod, and the diameter of the swelling rod is 1-5 mm.

2. The battery cell composite structure according to claim 1, wherein: The battery core is a cylindrical battery core.

3. The battery cell composite structure according to claim 1, wherein: The swelling rod placement hole is a cylindrical hole.

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