PRISMATIC BATTERY CELL WITH A ONE-WAY VALVE

Abstract

A prismatic battery cell comprises a cell casing, an electrolyte, and a sealing element. The cell casing has an internal cavity and a fill opening. The fill opening has an internal surface. The fill opening is in fluid communication with the environment and the internal cavity. The electrolyte is directed into the internal cavity through a one-way valve in the sealing element. The sealing element is disposed in the fill opening. The sealing element has an external sealing surface that forms a fluid seal with the internal surface of the fill opening. A valve is formed in the sealing element. The valve has an open position to allow the electrolyte to enter the internal cavity and a closed position to prevent the electrolyte from escaping from the internal cavity. The valve also allows the battery cell to degas after the formation process.

Description

INTRODUCTION

[0001] The present invention relates to a prismatic battery cell and, in particular, to a prismatic battery cell having a device for filling the battery cell with an electrolyte during manufacture.

[0002] Such a battery cell is described, for example, in the documents CN 2 06 893 706 U and CN 2 19 801 234 U.

[0003] Further prior art can also be found in the documents CN 2 17 641 721 U and US 2017 / 0 149 047 A1.

[0004] A rechargeable energy storage system (RESS), such as a prismatic battery cell, typically comprises a plurality of electrode stacks. Each electrode stack comprises an anode and a cathode separated by an electrically insulating separator material. The electrode stacks are typically placed side by side in a housing to protect them from the environment. The housing also serves to contain an electrolyte fluid within and around the electrode stacks. The electrolyte is introduced into the battery cell housing through a fill opening. During the manufacture of the prismatic battery cell, an electrolyte filling tool (i.e., a funnel, needle, or tube) is inserted into the fill opening, the battery cell is filled with electrolyte through the fill tool, and the fill tool is withdrawn from the fill opening.A temporary insert (i.e., a sealing plug) is positioned in the filler opening to prevent the contents of the housing from escaping through the filler opening. A formation process is initiated by applying current to the electrodes for a specific period of time. The temporary insert is removed from the filler opening. Gases are released from the housing through the filler opening. The filling tool is reinserted into the filler opening. The battery cell is filled with the electrolyte a second time, or several times as required. The filling tool is withdrawn from the filler opening. A sealing insert or plug is attached to the filler opening. A closure plate is placed over the sealing insert and welded to the battery cell housing.

[0005] While the state-of-the-art battery cell manufacturing methods and systems serve their purpose, there is still a need for a new and improved battery cell and a new and improved battery cell manufacturing process. Consequently, a battery cell manufacturing process with fewer manufacturing steps is required. SUMMARY

[0006] According to the invention, a prismatic battery cell is presented which is characterized by the features of claim 1.

[0007] According to another aspect of the present invention, the prismatic battery further comprises a closure plate disposed over and covering the sealing member.

[0008] According to another aspect of the present invention, the closure plate is attached to the cell housing to form a mechanical and fluid seal between the cell housing and the internal cavity.

[0009] According to a further aspect of the present invention, the inner surface of the filling opening comprises a first annular surface and a second annular surface.

[0010] According to a further aspect of the present invention, the sealing element has a second sealing annular surface forming a second fluid seal with the second annular surface of the filling opening.

[0011] According to a further aspect of the present invention, the second sealing annular surface of the outer sealing surface of the sealing element is formed on a conical portion of the sealing element at a second end of the sealing element.

[0012] According to a further aspect of the present invention, the sealing element is formed from a polymer and / or a polymer composite. The polymer and / or polymer composite comprises, for example, a silicone and / or a polyphenylene sulfide or a similar material.

[0013] Furthermore, a method for producing a prismatic battery cell is described. The method comprises filling an inner cavity of a cell housing of the prismatic battery cell with an electrolyte via the filler opening arranged on the cell housing, inserting a sealing element with a one-way valve into the filler opening of the cell housing, initiating a battery cell formation process, inserting a filler tube into the one-way valve of the sealing element, degassing the inner cavity of the battery cell, filling an inner cavity of the cell housing through the one-way valve of the sealing element, and removing the filler tube from the one-way valve of the sealing element.

[0014] According to yet another aspect of the present invention, the method further comprises attaching a closure plate over the sealing element and the filling opening by welding the closure plate to the cell housing. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The drawings described here are for illustrative purposes only. Fig. 1A shows a perspective view of a prismatic battery cell constructed in accordance with the present invention; Fig. 1B shows an enlarged view of a partial cross-section through the filling opening of the battery cell from Fig. 1A, illustrated according to the present invention; Fig. 2 shows a cross-sectional view through the sealing element of the battery cell from Fig. 1B; and Fig. 3 shows a flowchart of a method for manufacturing the prismatic battery cell according to the present invention. DETAILED DESCRIPTION

[0016] The following description is for illustrative purposes only.

[0017] With reference now to Fig. 1A is a perspective view of a prismatic battery cell 10 according to the present invention. The battery cell 10 includes a housing 12, a lid 14, terminals 16 and 18, a vent 20, and an electrolyte injection port or fill port 22. The housing 12 is shown in Fig. 1A and has a first side wall 24, a second side wall 26, a third side wall 28 (not shown), a fourth side wall 30 (not shown), and a bottom wall or bottom 32 (not shown), which form an inner cavity 34. The inner cavity 34 is enclosed by the cover 14. The present invention also provides other designs for the housing or casing 12 and is not limited to the embodiments shown in Fig. 1A. Furthermore, the housing 12 is configured to contain or accommodate a suitable electrolyte. The electrolyte is, for example, a liquid solution of organic solvents and lithium salts. Furthermore, a plurality of electrode stacks (not shown) are accommodated in the electrolyte contained in the housing 12. The electrode stacks comprise a negative electrode or anode electrode, a separator, and a positive electrode or cathode electrode. The anode electrode is generally a thin metal plate having a protruding electrode tab for establishing an electrical connection between the anode electrode and the pole 16 on the outside of the housing.Likewise, the cathode electrode is a thin metal plate with a protruding electrode tab for establishing an electrical connection between the cathode electrode and terminal 18 on the outside of the enclosure. The electrode tabs serve as current collectors. The voltage generated at the anode and cathode electrodes is transmitted via the terminals of the enclosure 12 to an external device (not shown). The anode electrode and the electrode tab are made of copper or another suitable material, for example, and are typically coated with graphite or graphite / silicon or other carbon-based materials, silicon oxide, or lithium-containing silicon.The cathode electrode and the electrode tab are made of, for example, aluminum or another suitable material and are typically coated with a lithium metal oxide such as lithium cobalt oxide (LCO) or lithium nickel cobalt aluminum (NCA) or lithium nickel cobalt manganese aluminum (NCMA) or lithium iron manganese phosphate (LFP / LFMP) or rich in lithium manganese (LMR).

[0018] The various metals coated with anode and cathode electrode materials (copper anode and aluminum cathode) of the prismatic battery 10 generate a galvanic reaction within the prismatic battery 10. The graphite, for example, of the anode electrode and the LCO, for example, of the cathode electrode, have different standard reduction potentials and are connected to an external circuit and separated from each other by the separator. The LCO with the lower potential oxidizes and releases electrons, while the graphite with the higher potential reduces and absorbs electrons. This process of releasing and absorbing electrons generates an electric current that can be used to power devices.

[0019] The separator is generally a thin, porous membrane or layer of material placed between the anode and cathode electrodes, preventing them from touching and causing a short circuit. The separator allows the lithium ions to pass through and complete the circuit. A porous and chemically stable composite material can be used as the separator, such as a composite made of polyethylene (PE), polypropylene (PP), or other natural materials. Inorganic nanoparticles such as TiO 2 , SiO 2 , Al 2 O 3 , AlO(OH) and ZrO 2used to manufacture coating composites for the separator. The separator increases the internal resistance of the prismatic battery 10, which can reduce the power output and efficiency of the battery. The internal resistance depends on the thickness, porosity, and composition of the separator. Preferably, a thinner, more porous, and more conductive separator can reduce the resistance and improve the performance of the battery 10. The separator is also selected to withstand high temperatures and manage thermal runaway, thus preventing an uncontrollable temperature rise due to exothermic reactions. In addition, the separator has a high melting point and a low shrinkage rate to avoid contact between the anode and cathode electrodes.The separator has sufficient mechanical strength to resist puncture, tear, or deformation during manufacture and operation of the battery cell 10. The separator is also dimensionally stable and flexible, allowing it to conform to the shape of the electrodes and accommodate volume changes during cycling. The separator is chemically inert and compatible with the electrolyte, electrodes, and other cell components. Furthermore, the separator has a low affinity for water or other contaminants that could contaminate the electrolyte or cause corrosion of the electrodes.

[0020] With further reference to Fig. 1A, a vent 20 is provided in the lid 14 at a suitable location on the surface of the lid 14. Alternatively, the vent 20 can also be located on the bottom of the enclosure 12. The vent 20 is in fluid communication with the internal cavity 34 of the enclosure 12. The vent 20 consists of a gas-permeable barrier, such as a material similar to that used for the enclosure 12, but the vent material is thinner than the enclosure 12. The excess pressure in the enclosure 12 caused by gas formation is relieved by venting the gas through the vent 20.

[0021] The filling opening 22 allows the inner cavity 34 of the housing 12 to be filled with the electrolyte during the manufacturing process of the battery cell 10. The filling opening 22 comprises an opening 36 (in Fig. 1B). The opening 36 is in fluid communication with the environment at a first end 38 and with the inner cavity 34 of the housing 12 at a second end 40.

[0022] With reference now to Fig. Figure 1B illustrates an enlarged partial cross-sectional view of the enclosure 12 at the fill port 22 according to the present invention. During assembly of the battery cell 10, which will be described in more detail below, a one-way valve or sealing member 44 is disposed within the opening 36 of the fill port 22. As will be described in more detail below, the sealing member 32 allows the internal cavity 34 to be filled with electrolyte and gas to escape from the internal cavity 34 during the battery cell manufacturing process. Furthermore, in accordance with one aspect of the present invention, a fill port closure plate 46 is provided to seal the fill port 22 after the manufacturing process is complete.

[0023] With reference to Fig. 2 shows a cross-sectional view through the sealing element 44 according to one aspect of the invention. The sealing element 44 is disposed within the electrolyte fill opening 22 and functions to allow the electrolyte to enter the internal cavity 34 and to prevent the electrolyte from exiting the internal cavity 34. The sealing element 44 has an outer sealing surface 50 for forming a fluid seal with the fill opening 22. The outer sealing surface 50 includes a first annular lip 52 having a first sealing surface 54 and an annular conical portion 56 having a second sealing surface 58. The first sealing surface 54 is disposed at a first end 60 of the sealing element 44, and the second sealing surface 58 is disposed at a second end 62 of the sealing element 44.

[0024] The sealing element 44 is made of a polymer or a polymer composite. According to one aspect of the present invention, the polymer or polymer composite is a silicone or a polyphenylene sulfide, or the like. The sealing element 44 plastically deforms at the sealing surface 54, 58 to form a liquid-tight seal with the fill opening 22.

[0025] The filling opening 22 has a first opening section 66 with a first diameter d 1 and a second opening portion 68 having a second diameter d 2 . The first diameter d 1 of the first opening section 66 is larger than the second diameter d 2the second opening 68. An inner surface 70 of the fill opening 22 is configured to form a fluid seal with the sealing element 44. Furthermore, the inner surface 70 of the fill opening 22 includes a first inner surface 72 of the first opening 66 of the fill opening 22 and a second inner surface 76 of the second opening 68. More specifically, the fluid seal is formed by an interference fit of the sealing element 44 in the fill opening 22. The interference fit causes the first sealing surface 54 of the first annular lip 52 to deform and contact the first inner surface 72 of the first opening 66 and the second sealing surface 58 of the annular conical portion 56 to contact the second inner surface 76 of the second opening 68. The fluid seal is intended to prevent the electrolyte from escaping from the inner cavity 34 of the battery cell 10.

[0026] The sealing element 44 is also intended to allow the inner cavity to be filled with the electrolyte while the sealing element 44 is located in the fill opening 22. Accordingly, the sealing element 44 comprises an inner tubular body 80. The inner tubular body 80 has a ring 82 at a first end 84 of the inner tubular body 80 and a pivotable flap 86 at a second end 88 to selectively enclose the inner tubular body 80 and form a one-way valve. The ring 82 has a central opening 90. The central opening 90 of the ring 82 and the pivotable flap 86 can be moved to an open state "S aa ' and 'S fa “ so that liquid (ie electrolyte) can enter the inner cavity 34 of the battery cell 10, and into a closed state “S ac ' and 'S fc", so that liquid can escape from the inner cavity 34. The central opening 90 and the pivoting flap 86 are in the closed position or in the closed state S ac and S fc preloaded and thus form the one-way fluid seal or one-way valve that prevents fluid from escaping from the inner cavity 34.

[0027] The central opening 90 of the ring 82 and the pivotable flap 86 are moved into the open state S by a force applied by inserting a line or a needle or a funnel 92 ao and S foMore specifically, the funnel 92 is inserted into the ring 82 and pressed inward into the inner tubular body 80 of the sealing element 44 and against the pivotable flap 86. By inserting the funnel 92, the ring 82 is plastically deformed so that the funnel can pass through the ring 82. As the funnel 92 is further advanced into the inner tubular body 80 and against the pivotable flap 86, the pivotable flap 86 is plastically deformed at a hinge portion 94 so that the flap 86 can open and rotate away from the end 88 of the inner tubular body 80, allowing liquid to enter the inner cavity 34. Upon removal of the funnel 92, the ring 82 closes and returns to its original shape or state S acback, and the flap 86 returns to its original position (rotates towards the open end 88), enclosing the end 88 of the inner tubular body 80 and into the closed position or closed state S fc returns.

[0028] With reference now to Fig.3 is a flowchart of a method 100 for manufacturing a battery cell 10 according to the present invention. The method 100 begins in block 102. In block 102, the dry or empty casing of the prismatic battery cell is positioned for filling with electrolyte. In block 104, the electrolyte is introduced through the fill opening 22 into the internal cavity of the battery cell. In block 106, the sealing element 44 is pressed into the fill opening 22, forming a liquid seal as described above. In block 108, a formation process is initiated. Current is applied to the electrodes of the battery cell 10 at a specific temperature and then removed to initially charge and discharge the battery cell, thereby conditioning the internal structure of the battery cell. A solid electrolyte interphase forms on the anode electrode.The solid electrolyte interphase is important for the stability and service life of the battery cell. Furthermore, gas is generated during the formation process, which must be vented from the inner cavity 34 of the battery cell 10. In block 110, the funnel 92 is inserted into the inner tubular body 80 of the sealing element 44 to move the ring 82 of the sealing element 44 into the open state S. ao and the flap 86 in the open state S fo to force. The degassing or removal of the gas generated during the formation process takes place in block 112, where the gas is discharged through the funnel 92. In block 114, the electrolyte is again introduced through the funnel 92 into the inner cavity 34 of the battery cell 10. Once the electrolyte substantially fills the inner cavity 34, the funnel 92 is removed in block 116, thereby moving the ring 82 and the flap 86 into the closed position or closed state S ac and Sfc return. In block 118, the closure plate 46 is mounted over the sealing element 44 and covers the filler opening 22. In block 120, the closure plate 46 is welded to the housing 12 of the battery cell.

[0029] The present invention has many advantages and benefits over existing systems and methods for manufacturing a prismatic battery cell. For example, in some aspects of the present invention, the process for manufacturing the prismatic battery cell is simplified. More specifically, the sealing element 44 of the present invention reduces the number of steps required to fill the battery cell with electrolyte, degas the battery cell, and then refill the battery cell with electrolyte. This reduces the overall time required to manufacture the battery cell.

Claims

[1] Prismatic battery (10) comprising: a cell housing (12) having an internal cavity (34) and a fill opening (22) having an internal surface (70), the fill opening (22) being in fluid communication with the environment and the internal cavity (34); an electrolyte located in the inner cavity (34); a sealing element (44) arranged in the filling opening (22), wherein the sealing element (44) has an outer sealing surface (50) which forms a fluid seal with the inner surface (70) of the filling opening (22), and wherein the sealing element (44) has a valve formed in the sealing element (44); and wherein the valve has an open position to allow the electrolyte to enter the inner cavity (34) and a closed position to prevent the electrolyte from exiting the inner cavity (34); wherein the outer sealing surface (50) of the sealing element (44) has a first sealing annular surface (54) forming a first fluid seal with the first annular surface (72) of the fill opening (22) and is formed on an annular lip (52) at a first end (60) of the sealing element (44); the valve further comprising a tubular body (80) having an inner annular lip (82) at a first end, the inner annular lip (82) forming a ring (82) and being located at the same location in the axial direction of the sealing element (44) as the annular lip (52) of the annular surface (54), and a flap (86) at a second end of the tubular body (80), the flap (86) being sealed against the tubular body (80) in the closed position of the valve to form a fluid seal, and the flap (86) being positioned remote from the tubular body (80) in the open position of the valve to enable fluid communication with the internal cavity (34). [2] The prismatic battery (10) of claim 1, further comprising a closure plate (46) disposed over and covering the sealing member (44). [3] The prismatic battery (10) of claim 2, wherein the closure plate (46) is secured to the cell casing (12) to form a mechanical and fluid seal between the cell casing (12) and the internal cavity (34). [4] The prismatic battery (10) of claim 1, wherein the inner surface (70) of the fill opening (22) has a second annular surface (76). [5] The prismatic battery (10) of claim 1, wherein the sealing member (44) has a second sealing annular surface (58) forming a second fluid seal with the second annular surface of the fill opening (22). [6] The prismatic battery (10) of claim 1, wherein the second sealing annular surface (58) of the outer sealing surface (50) of the sealing member (44) is formed on a conical portion (56) of the sealing member (44) at a second end (62) of the sealing member (44). [7] Prismatic battery (10) according to claim 1, wherein the sealing element (44) is formed from a polymer and / or a polymer composite.

Images