JP4586341B2 - Square battery - Google Patents

Description

  The present invention relates to a structure of a prismatic battery in which a substrate built in the prismatic battery is not easily damaged.

  In recent years, with the miniaturization of electronic devices, various types of batteries used in electronic devices are also miniaturized, and there are various types of batteries. In particular, a rectangular lithium ion battery can be used for a mobile phone, a notebook personal computer, and the like because it can increase the energy density.

Secondary batteries such as lithium ion batteries incorporate a substrate mounted with a temperature coefficient protection element, for example, PTC (Positive Temperature Coefficient), in order to prevent overcharging. Since the lithium ion battery is small, it can be removed and carried, for example, in a mobile phone. For this reason, it is easy to receive an impact from the outside, and the substrate built in the lithium ion battery is easily damaged. The structure of the prismatic battery that protects the substrate from external impact is described in Patent Document 1 below.
Japanese Patent Laid-Open No. 11-242949

  FIG. 5 is a diagram showing a configuration of a conventional prismatic battery. Reference numeral 21 represents a substrate on which elements constituting the protection circuit are mounted. The substrate 21 is mounted on the cell 24 via the holder 22. Since the holder 22 engages with the substrate 21, a gap is generated between the holder 22 and the lead plate 23. For this reason, if a lateral twisting load is applied to the entire battery after the parts such as the substrate 21 are mounted on the cell 24, a load is applied to the lead plate 23, whereas a lead is applied to the holder 22. Due to the gap between the plate 23 and the holder 22, no twisting load is applied. For this reason, the holder 22 and the lead plate 23 may be damaged, and the holder 21 and the substrate 21 to be mounted may be damaged.

  In addition, the prismatic battery in which each component such as the substrate 21 is mounted on the cell 24 is accommodated in the lower case 20 and the upper case 25. The volume of the entire square battery is lost due to the thickness of the holder.

  Accordingly, it is an object of the present invention to provide a highly reliable prismatic battery having a structure in which a load is not applied to the substrate even when an external impact is applied to the prismatic battery.

  Another object of the present invention is to provide a prismatic battery having a structure that is also efficient in terms of volume.

In order to solve the above-described problem, the invention of claim 1 is a prismatic battery in which a substrate is housed.
A rectangular battery cell;
A holder in which at least four corner edges of the peripheral part are bent to form a flat surface in all directions, a contact surface that contacts the upper end surface of the battery cell is formed, and a space is formed between the battery cell,
A substrate placed on the upper end surface of the battery cell and housed in the space of the holder;
Ri Do and a positive electrode having a protrusion protruding exposed to the outside, which is laminated on the holder,
The holder has a protrusion,該Tokki is welded is inserted into the hole of the locking tab, a rectangular battery that has been secured.

According to the present invention, since the load applied to the positive electrode is applied directly to the cell via the holder, the positive electrode is not deformed, and the substrate is not loaded, so that the substrate can be prevented from being damaged. Further, the load applied to the positive electrode can be applied evenly to the battery cells when the end of the holder is in contact with the battery cell in a flat surface.

  Furthermore, since no holder is interposed between the substrates, a useless space is not formed between the holder and the cell, and the prismatic battery can be further downsized.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows parts constituting one example of the prismatic battery of the present invention. Reference numeral 1 indicates a battery cell. The battery cell is, for example, a lithium ion secondary battery main body housed in a negative electrode can. A washer 2 made of an insulating resin is attached to the positive electrode of the battery cell 1. Since the washer 2 is intended for insulation, for example, paper is used.

  Reference numeral 3 indicates a substrate. The substrate 3 is placed on the upper end surface of the battery cell 1 on the negative electrode side via the washer 2. For example, a PTC element is mounted on the substrate 3. In a secondary battery such as a lithium ion battery, prevention of overcharging is a major issue for safety. Therefore, a substrate on which a PTC element is mounted is used in many secondary batteries.

  A PTC element extremely increases its resistance when heated above a certain temperature. For this reason, the charging / discharging current can be stopped when the battery reaches an abnormally high temperature. Further, the PTC element has resistance reversibility, and after the PTC element is activated and the current is stopped, if the battery temperature decreases, the element resistance decreases, and the battery can be used again.

Reference numeral 4 denotes a holder. The holder 4 is mounted so as to cover the substrate 3 and is intended for insulation and reinforcement. Since the purpose is insulation, the holder 4 is generally made of resin. The holder 4 is fixed to the battery cell 1 by fixing tabs 6a and 6b. As shown in FIG. 2, the holder 4 is provided with a protrusion 11. Further, the fixing tab 6a has a step for engagement, and a hole 10 is provided at substantially the center of the step for engagement. The protrusion 11 of the holder 4 is inserted into the hole 11 of the fixing tab 6a and welded from the outside, whereby the holder 4 and the fixing tab 6a are fixed. The fixing tab 6b and the holder 4 arranged on the opposite end face of the holder 4 are also fixed in the same manner. Iron, nickel or the like is used for the fixing tabs 6a and 6b. The edge of the holder 4 is bent, and a sufficient space for arranging the substrate 3 between the holder 4 and the battery cell 1 is formed. The contact surface where the holder 4 and the battery cell 1 are in contact with each other has a structure in which flat surfaces are formed on all sides in order to apply a load evenly.

  A positive electrode 5 is placed on the upper surface of the holder 4. If it demonstrates with reference to FIG. 3, the opening 12 will be provided in a part of mounting surface of the holder 4 and the positive electrode 5. FIG. Since the holder 4 is laminated with the substrate 3 so as to cover the substrate 3 as described above, the substrate 3 is exposed through the opening 12 of the holder 4.

  A tongue piece 14 for welding to the substrate 3 is provided at one end of the positive electrode 5. The positive electrode 5 and the holder 4 are welded to a convex portion 15 a and a concave portion 13 a provided in the holder 4. On the opposite end face, the convex portion 15b and the concave portion 13b are fitted and welded.

  Since the load from above on the positive electrode 5 is transmitted to the holder 4 in the vertical direction, the holder 4 may bend. For this reason, it is desirable that the end face of the positive electrode 5 be in contact with the thick part of the holder 4. The positive electrode 5 is provided with a resin cover 7 to conceal the end face of the positive electrode and improve the appearance.

  FIG. 4 is a cross-sectional view of the above-described embodiment. Transmission of a load applied to the positive electrode 5 will be described with reference to FIG. There is a space in the center of the surface where the positive electrode 5 and the holder 4 are in contact. Therefore, the load applied to the positive electrode 5 is transmitted to the end of the holder 4. The end of the holder 4 is attached to the battery cell 1 via the washer 2. That is, the load applied to the positive electrode 5 is transmitted to the battery cell 1 through the holder 4, and the load on the positive electrode 5 is not applied to the substrate 3. As a result, the load applied to the positive electrode can prevent the load from being transmitted to the substrate 3, and the substrate can be prevented from being damaged.

  The present invention is not limited to the above-described embodiment, and various modifications and applications are possible without departing from the gist of the present invention. For example, in the above-described embodiment, a lithium ion battery has been described as the type of secondary battery, but the present invention can also be applied to other prismatic secondary batteries.

It is a basic diagram which shows the member which comprises an example of the square battery of this invention. It is a one part enlarged view of the member which comprises an example of the square battery of this invention. It is a one part enlarged view of the member which comprises an example of the square battery of this invention. It is sectional drawing of an example of the square battery of this invention. It is a basic diagram which shows the conventional square battery.

Explanation of symbols

1 Battery cell 3 Substrate 4 Holder 5 Positive electrode 6a, 6b Fixing tab

Claims (4)

In the rectangular battery in which the substrate is housed,
A rectangular battery cell;
A holder in which at least four corner edges of the peripheral part are bent to form a flat surface in all directions, a contact surface that contacts the upper end surface of the battery cell is formed, and a space is formed between the battery cell,
A substrate placed on the upper end surface of the battery cell and housed in the space of the holder;
Ri Do and a positive electrode having a protrusion protruding exposed to the outside, which is laminated on the holder,
The holder has a protrusion,該Tokki is by welding, is fixed inserted and fitted into the hole of the locking tab, prismatic cell with said fixing tab and the battery cell Ru fixed. A positive electrode is placed on the upper surface of the holder, and an opening is provided in a part of the mounting surface of the holder and the positive electrode,
The prismatic battery according to claim 1, wherein the substrate is exposed through the opening of the holder, and the substrate and a tongue piece provided at one end of the positive electrode are welded .   The prismatic battery according to claim 1, wherein the substrate is provided with a PTC element. The prismatic battery according to claim 1, wherein a convex portion provided on the positive electrode and a concave portion provided on the holder are fitted and welded.

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