Lithium primary battery

Abstract

This lithium primary battery is provided with: an electrode body in which a positive electrode and a negative electrode are wound in a spiral shape with a separator therebetween; a negative electrode lead that covers a part of the negative electrode and is electrically connected to the negative electrode; and a protective tape that covers a part of the negative electrode lead and is wider than the negative electrode lead. The outermost periphery of the electrode body is the positive electrode, and in the electrode body, the negative electrode is wound by more than two circles. In a cross-section perpendicular to the center axis of the electrode body, a straight line A connecting the center axis and the center X of the protective tape, a straight line B passing through one end of the protective tape and parallel to the straight line A, and a straight line C passing through the other end of the protective tape and parallel to the straight line A are taken into consideration, and the center X of the protective tape and the center X of the protective tape are aligned with each other in the cross-section perpendicular to the center axis of the electrode body. The outer peripheral end of the positive electrode is located in a region sandwiched between the straight line B and the straight line C. And the designed energy density is 850 Wh / L or above.

Description

Technical Field

[0001] The invention relates to a lithium primary battery. Background Art

[0002] In recent years, the application range of electronic devices using lithium primary batteries as power sources has been expanding, and there is a trend to use lithium primary batteries in long-term device driving. In lithium primary batteries, the negative electrode uses a foil of metal lithium or lithium alloy (hereinafter referred to as negative electrode foil). The negative electrode foil has the functions of both negative electrode active material and negative electrode collector.

[0003] When the discharge reaction proceeds, there will be areas where lithium is depleted and areas where lithium remains. When the area where lithium remains is isolated by the area where lithium is depleted, the lithium in the isolated area is cut off from the electrical connection with the negative electrode lead and no longer participates in the discharge. As a result, there is a tendency for the actual battery capacity to be smaller than the designed capacity.

[0004] In lithium primary batteries using an electrode body in which the positive electrode and the negative electrode are wound in a spiral shape, the reaction of the negative electrode foil is uneven, resulting in uneven reaction. In particular, at the outer peripheral end of the positive electrode where the winding ends, a large pressure is applied, and the distance between the electrodes becomes closer, so that the discharge reaction is likely to proceed radially from the outer peripheral end of the positive electrode, which is likely to cause the negative electrode foil to break.

[0005] Patent document 1 proposes a non-aqueous electrolyte battery, which is composed of a spiral electrode body formed by winding a strip-shaped negative electrode with light metal as an active material and a strip-shaped positive electrode with a separator in between, and the width of the above-mentioned negative electrode is made smaller than the width of the positive electrode, and the negative electrode collector is crimped to the negative electrode in a manner that does not cover the entire length direction of the above-mentioned negative electrode. In this non-aqueous electrolyte battery, the negative electrode collector is arranged within a semicircle of 180° along the winding direction from the end of the positive electrode of the electrode body to uniformly consume the light metal of the negative electrode during discharge.

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Utility Model Publication No. 06-6462 Summary of the invention

[0009] As the energy density of batteries increases, when attempting to realize a battery with a high energy density (for example, 850Wh / L or more), the technique described in Patent Document 1 is insufficient and may fail to suppress foil breakage.

[0010] One aspect of the present invention relates to a lithium primary battery, comprising: an electrode body in which a positive electrode and a negative electrode are wound in a spiral shape with a separator interposed therebetween; a negative electrode lead attached to the negative electrode in a manner covering a portion of the negative electrode and electrically connected to the negative electrode; and a protective tape covering a portion of the negative electrode lead and being wider than the negative electrode lead, wherein the outermost periphery of the electrode body is the positive electrode, in the electrode body, the negative electrode is wound more than two turns, the negative electrode lead is not arranged at the innermost periphery of the negative electrode and the outermost periphery of the negative electrode, and in a cross section perpendicular to the central axis of the electrode body, when considering a straight line A connecting the central axis and a center X of the protective tape, a straight line B passing through one end of the protective tape and parallel to the straight line A, and a straight line C passing through the other end of the protective tape and parallel to the straight line A, the outer peripheral end of the positive electrode is located in a region sandwiched by the straight line B and the straight line C, and the designed energy density of the lithium primary battery is 850Wh / L or more.

[0011] Effects of the Invention

[0012] According to the present invention, even when the energy density is set to a high level of 850Wh / L or more, it is possible to suppress the breaking of the negative electrode at the end of discharge of a lithium primary battery and improve the utilization rate of the negative electrode. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1A This is a schematic cross-sectional view of a lithium primary battery according to one embodiment of the present invention.

[0014] Figure 1B This is a schematic cross-sectional view showing an example of the structure of an electrode body used in a lithium primary battery according to an embodiment of the present invention.

[0015] Figure 2A This is a schematic diagram showing an example of the structure of a negative electrode used in a lithium primary battery according to one embodiment of the present invention.

[0016] Figure 2B This is a schematic diagram showing an example of the structure of a negative electrode used in a lithium primary battery according to one embodiment of the present invention.

[0017] Figure 2C This is a schematic cross-sectional view showing an example of the structure of an electrode body used in a lithium primary battery according to an embodiment of the present invention.

[0018] Figure 2D This is a schematic diagram showing an example of the structure of a negative electrode used in a lithium primary battery according to one embodiment of the present invention.

[0019] Figure 3 This is a schematic diagram showing an example of the structure of a negative electrode used in a lithium primary battery according to one embodiment of the present invention.

[0020] Figure 4 This is a diagram showing evaluation results of a lithium primary battery according to an embodiment of the present invention. DETAILED DESCRIPTION

[0021] Hereinafter, the embodiments of the sealed battery of the present invention will be described with examples, but the present invention is not limited to the examples described below. In the following description, specific numerical values ​​and materials are sometimes exemplified, but as long as the effect of the present invention can be obtained, other numerical values ​​and materials can also be applied. In this specification, the description of a range such as "numerical value A to numerical value B" includes numerical value A and numerical value B, and can be read as "above numerical value A and below numerical value B". In the following description, when multiple lower limits and multiple upper limits of numerical values ​​related to specific physical properties, conditions, etc. are exemplified, as long as the lower limit is not above the upper limit, any one of the multiple lower limits exemplified can be arbitrarily combined with any one of the multiple upper limits exemplified. When multiple materials are exemplified, one can be selected from them alone for use, or two or more can be used in combination.

[0022] In addition, the present invention includes a combination of matters recorded in two or more claims arbitrarily selected from a plurality of claims recorded in the scope of the attached claims. That is, as long as no technical contradiction occurs, matters recorded in two or more claims arbitrarily selected from a plurality of claims recorded in the scope of the attached claims may be combined.

[0023] Hereinafter, a specific embodiment of the present invention will be described with reference to the accompanying drawings. However, the present embodiment is not limited thereto. It should be noted that in the following illustrations, the same symbols are used for components having the same functions.

[0024] (Lithium primary battery)

[0025] Figure 1A , a front view showing a cross section of a portion of a lithium primary battery 10 according to an embodiment of the present invention is shown.

[0026] The lithium primary battery 10 includes a bottomed cylindrical battery can 100, a wound electrode body 200 housed in the battery can 100, and a sealing plate 300 that blocks the opening 100A1 of the battery can 100. The battery can 100 includes a barrel 100A having openings 100A1 and 100A2 on opposite sides of each other, and a bottom 100B that blocks the opening 100A2. The sealing plate 300 is fixed to the vicinity of the opening 100A1 of the battery can 100 by welding. An opening is formed in the center of the sealing plate 300, and an external terminal 330 is arranged at the opening. An insulating gasket 310 is arranged between the external terminal 330 and the sealing plate 300. The electrode body 200 is housed inside the battery can 100 together with the non-aqueous electrolyte 204. To prevent internal short circuit, an upper insulating plate 230A and a lower insulating plate 230B are respectively disposed on the upper and lower parts of the electrode body 200. That is, the upper insulating plate 230A is disposed between the sealing plate 300 and the electrode body 200, and the lower insulating plate 230B is disposed between the bottom 100B of the battery can 100 and the electrode body 200.

[0027] The electrode body 200 is formed by winding a sheet-shaped positive electrode 201 and a sheet-shaped negative electrode 202 in a spiral shape with a central axis 10AX as the center through a sheet-shaped separator 203. The negative electrode 202 has an inner peripheral surface 202A facing the central axis 10AX in the electrode body 200 and an outer peripheral surface 202B located on the opposite side of the inner peripheral surface 202A and facing the outside of the electrode body 200. An internal lead 210 (negative electrode lead) is connected to the negative electrode 202. In an embodiment, the internal lead 210 is connected to the inner peripheral surface 202A of the negative electrode 202. The internal lead 210 is connected to the external terminal 330 by welding or the like. Another internal lead 220 is connected to the positive electrode 201. The internal lead 220 is connected to the inner surface of the battery can 100 by welding or the like.

[0028] Figure 1B Yes means Figure 1A The schematic cross-sectional view of an example of an electrode body 200 used in the lithium primary battery 10 of the present embodiment shown in FIG. The electrode body 200 is formed by winding a positive electrode 201 and a negative electrode 202 in a spiral shape with a separator 203 interposed therebetween. The outermost and innermost circumferences of the electrode body 200 are the positive electrode 201. It should be noted that Figure 1B In order to avoid making the drawing complicated, the separator 203 is omitted, and only the wound state of the positive electrode 201 and the negative electrode 202 is shown.

[0029] The lithium primary battery 10 of one embodiment of the present invention includes an electrode body 200 in which a positive electrode 201 and a negative electrode 202 are wound in a spiral shape with a separator 203 interposed therebetween, a negative electrode lead 210 attached to the negative electrode 202 so as to cover a portion of the negative electrode 202 and be electrically connected to the negative electrode 202, and protective tapes 240 and 241 covering a portion of the negative electrode lead 210 and being wider than the negative electrode lead 210. The outermost periphery of the electrode body 200 is the positive electrode 201. The negative electrode 202 is generally in the shape of a strip extending elongated with a winding direction Dw as a longitudinal direction, and the negative electrode lead 210 protrudes from the negative electrode 202 in a central axis direction Da, which is a width direction perpendicular to the longitudinal direction.

[0030] The lithium primary battery 10 uses the outermost periphery of the electrode body 200 as the positive electrode 201 to increase the amount of positive electrode active material, which makes it easier for the negative electrode 202 to consume lithium and improve the utilization rate of the negative electrode. To further improve the utilization rate of the negative electrode, the outermost and innermost peripheries of the electrode body 200 can be used as the positive electrode 201.

[0031] In the electrode body 200 , the negative electrode 202 is wound more than two times. In this case, the lithium primary battery 10 satisfies the following conditions (I) and (II).

[0032] (I) The negative electrode lead 210 is not disposed at the innermost circumference of the negative electrode 202 or the outermost circumference of the negative electrode 202 .

[0033] (II) In a cross section perpendicular to the central axis 10AX (the central axis of winding) of the electrode body 200, when considering a straight line A connecting the central axis 10AX and the center X of the protective tape 240, a straight line B passing through one end of the protective tape 240 and parallel to the straight line A, and a straight line C passing through the other end of the protective tape 240 and parallel to the straight line A, the outer peripheral end of the positive electrode 201 is located in a region sandwiched by the straight line B and the straight line C. In addition, the protective tape 240 is located between the outer peripheral end of the positive electrode 201 and the central axis 10AX of the electrode body 200.

[0034] In other words, conditions (I) and (II) mean that the protective tape 240 is located between the innermost periphery of the negative electrode 202 and the outermost periphery of the negative electrode 202 and is provided so as to intersect a straight line connecting the central axis 10AX of the electrode body 200 and the outer peripheral end of the positive electrode 201 .

[0035] If the outermost periphery of the electrode body 200 is the positive electrode 201, it is easy to apply a large pressure to the outer peripheral end (positive electrode terminal end) of the winding end side of the positive electrode 201. As the discharge of the lithium primary battery 10 proceeds, the positive electrode 201 expands and contacts the inner surface of the battery can through the separator 203. As a result, the pressure in the radial straight line from the outer peripheral end of the positive electrode 201 to the center of the electrode body 200 and the vicinity of the straight line becomes the highest, and the distance between the positive and negative electrodes becomes smaller. As a result, it is easy to carry out the discharge reaction along the above-mentioned radial straight line, and it is easy to preferentially consume the lithium of the negative electrode 202. As a result, the area where lithium remains is cut off by the area where lithium is depleted along the above-mentioned radial straight line, thereby being isolated. The lithium in the isolated area is cut off from the electrical connection with the negative electrode lead 210 and no longer participates in the discharge.

[0036] However, in the lithium primary battery 10 of the present embodiment, the protective tape 240 is provided so as to intersect the straight line in the radial direction extending from the outer peripheral end of the positive electrode to the center of the electrode body 200. The insulating protective tape 240 covers at least a portion of the negative electrode lead 210 in order to prevent a short circuit between the negative electrode lead 210 and the positive electrode 201. The protective tape 240 is provided so as to cover a portion of the negative electrode 202. The protective tape 240 can be more difficult for the electrolyte 204 to penetrate than the separator 203, or the electrolyte 204 can not penetrate. As a result, in the region of the negative electrode 202 covered by the protective tape 240, the discharge reaction is difficult to proceed compared with other regions of the negative electrode 202.

[0037] As described above, the discharge reaction is easy to proceed in the radial straight line A and the vicinity of the straight line A from the outer peripheral end of the positive electrode to the center O of the electrode body 200. However, if the protective tape 240 is provided in a manner that crosses the radial straight line A, since an area covered by the protective tape 240 where the discharge reaction is difficult to proceed is sandwiched along the radial direction, the area covered by the protective tape 240 is utilized to suppress the excessive discharge reaction in the radial direction, so that the discharge reaction can be uniformly performed in the entire negative electrode 202. As a result, the utilization rate of the negative electrode 202 can be improved while suppressing the formation of isolated areas (i.e., broken foil) due to lithium depletion in the negative electrode 202.

[0038] The lithium in the negative electrode 202 is gradually depleted from the end portion where pressure tends to be greater toward the center portion. Therefore, by arranging the negative electrode lead 210 near the center of the negative electrode 202, depletion of lithium around the negative electrode lead 210 is suppressed.

[0039] Here, the so-called negative electrode 202 is wound more than 2 times, which means that the number of windings from the winding start side of the negative electrode 202, that is, the innermost circumferential end to the outer circumferential end of the winding end side in the electrode body 200 is greater than 2 times. However, in the unused and undischarged state, there is a case where areas where lithium is not formed are set at both ends in the winding direction Dw of the negative electrode 202, and the areas where lithium is not formed are not included in the ends. That is, the so-called inner circumferential end of the winding start side of the negative electrode 202 means the innermost circumferential position of the winding start side in the area where lithium is formed. Similarly, the so-called outer circumferential end of the winding end side of the negative electrode 202 means the outermost circumferential position of the winding end side in the area where lithium is formed.

[0040] The innermost circumference of the electrode plate refers to the range of one circle starting from the inner circumference end of the winding start side of the electrode plate. The outermost circumference of the electrode plate refers to the range of one circle starting from the outer circumference end of the winding end side of the electrode plate. Therefore, the negative electrode lead 210 is not arranged at the innermost circumference of the negative electrode 202 and the outermost circumference of the negative electrode 202, which means that the center of the negative electrode lead 210 is between the position of winding one circle starting from the inner circumference end of the winding start side of the negative electrode 202 and the position in the direction Dc opposite to the winding direction Dw starting from the outer circumference end of the winding end side of the negative electrode 202.

[0041] The so-called number of turns (winding number) of the electrode plate is the value obtained by adding 1 to the number of passes, which means how many times (weeks) the angular position of the inner peripheral end of the electrode plate on the winding start side passes through the winding direction Dw centered on the central axis 10AX from the inner peripheral end of the electrode plate on the winding start side to the outer peripheral end of the electrode plate on the winding end side. For example, Figure 1B From the inner peripheral end of the winding start side of the negative electrode 202 to the outer peripheral end of the winding end side, the angular position of the inner peripheral end of the winding start side of the negative electrode 202 centered on the central axis 10AX passes four times (4 turns), so the number of turns of the negative electrode 202 is 5 turns.

[0042] As described above, the protective tape is wider than the negative electrode lead 210. Here, “the protective tape is wider than the negative electrode lead 210” means that the width of the protective tape 240 is greater than the width of the negative electrode lead 210 in the cross section perpendicular to the central axis 10AX of the electrode body 200. That is, the width of the protective tape 240 in the winding direction Dw is greater than the width of the negative electrode lead 210 in the winding direction Dw. Typically, in this cross section, the protective tape 240 is configured to cover the entirety of at least one side of the negative electrode lead 210. That is, in this cross section, the protective tape 240 covers the negative electrode lead 210 beyond both ends of the negative electrode lead 210.

[0043] The condition (II) is described in more detail below.

[0044] In the cross section of the electrode body 200 (wound body) on a surface perpendicular to the central axis 10AX of the winding, a straight line A is defined that connects the center (central axis 10AX) O of the electrode body 200 and the center X of the protective tape 240. The end position of the protective tape 240, which is located on the winding end side of the wound body in the winding direction Dw, is set to Y, and the end position of the protective tape 240, which is located on the winding start side of the wound body in the direction Dc opposite to the winding direction Dw, is set to Z. A straight line B passing through the position Y and parallel to the straight line A and a straight line C passing through the position Z and parallel to the straight line A are defined. The position R of the outer peripheral end on the winding end side of the positive electrode 201 is within the region sandwiched by the straight line B and the straight line C. In addition, the protective tape 240 is located between the outer peripheral end of the positive electrode 201 and the central axis 10AX of the electrode body 200 (refer to Figure 1B ). It should be noted that, although there is a case where a region where the positive electrode active material layer is not formed and the positive electrode collector is exposed is provided at the outer peripheral end of the winding end side of the positive electrode 201 and its vicinity, the region where the positive electrode collector is exposed is not included in the end. The so-called outer peripheral end of the winding end side of the positive electrode 201 is the position of the outermost end of the winding end side in the region where the positive electrode active material layer is formed. It should be noted that in the above description, the so-called cross-section perpendicular to the central axis 10AX of the electrode body 200 is, more specifically, a cross-section perpendicular to the central axis 10AX of the electrode body 200, and is a cross-section of the portion where the positive electrode 201, the negative electrode 202, the negative electrode lead 210 and the protective tape 240 are present.

[0045] The winding state of the negative electrode 202 in the electrode body 200 can be analyzed by removing the electrode body 200 from the battery 10. The state of the electrode body 200 can be obtained by obtaining a cross section of an unused battery 10 perpendicular to the central axis 10AX using X-ray CT (Computed Tomography) and performing image analysis on the cross section. It should be noted that when the electrode body 200 is arranged in a cylindrical battery can, in the cross section of the electrode body 200 parallel to the bottom of the battery can, the midpoint between the position R of the outer peripheral end of the positive electrode 201 closest to the battery can as the winding end side and the position on the positive electrode 201 farthest from the position R (i.e., the position away from the position R toward the winding start side, that is, the position 0.5 turns away in the direction Dc opposite to the winding direction Dw) can be set as the position of the central axis 10AX of the electrode body 200.

[0046] Figure 2A and Figure 2B2 is a schematic diagram showing the structure of the negative electrode 202 before winding used in the lithium primary battery 10 of the present embodiment. The negative electrode lead 210 connected to the inner peripheral surface 202A of the negative electrode 202 has an inner peripheral surface 210A and an outer peripheral surface 210B. In the lithium primary battery 10, a protective tape 240 covering a portion of the surface 210A of the negative electrode lead 210 is provided. The protective tape 240 is also connected to and covers the portion around the negative electrode lead 210 in the inner peripheral surface 202A of the negative electrode 202. Another protective tape 241 covers the outer peripheral surface 210B of the negative electrode lead 210. The portion of the negative electrode lead 210 installed in the surface 202B of the negative electrode 202 opposite to the surface 202A to which the negative electrode lead 210 is installed is not covered by the protective tape 241. That is, the other protective tape 241 does not cover the surface 202B of the negative electrode 202, but exposes the surface 202B. For example, the negative electrode lead 210 is attached and mounted on the inner peripheral surface 202A (the inner side of the winding, that is, the main surface facing the central axis 10AX) of the negative electrode 202. In this case, at least a portion of the portion of the inner peripheral surface 202A where the negative electrode lead 210 is attached is covered by the protective tape 240. On the other hand, since the outer peripheral surface 202B of the negative electrode 202 to which the negative electrode lead 210 is not attached is not covered by the protective tape 241, the lithium in the attached portion can be used during discharge, and the utilization rate of the negative electrode 202 can be further improved.

[0047] Figure 2C This is a schematic cross-sectional view showing an example of the structure of another electrode body used in the lithium primary battery according to one embodiment of the present invention. Figure 2D Yes means Figure 2C A schematic diagram of an example of the structure of the negative electrode of the electrode body shown. Figure 2C and Figure 2D In, with Figure 1B and Figure 2B The same parts are marked with the same reference numerals. Figure 2C and Figure 2D The electrode body shown does not have Figure 1B , Figure 2B The electrode body shown in the figure has a protective tape 241, but includes a protective tape 242 covering the surface 210B of the first portion 211 of the negative electrode lead 210. The protective tape 242 extends to the surface 202B of the negative electrode 202. With this structure, the utilization rate of the negative electrode 202 can also be improved.

[0048] The protection tapes 241 and 242 are less susceptible to permeation of the electrolyte 204 than the separator 203, or are impermeable to the electrolyte 204. The protection tapes 241 and 242 may be made of the same material as the protection tape 240, or may be made of a different material.

[0049] In the lithium primary battery 10, a strip-shaped member may be provided between the negative electrode 202 and the separator 203 so as to cover a portion of the negative electrode 202. By providing the strip-shaped member between the negative electrode 202 and the positive electrode 201 in the region of the negative electrode 202 covered by the strip-shaped member, the discharge reaction is difficult to proceed, and lithium is likely to remain. As a result, by forming a region where lithium remains, isolation of lithium is suppressed, and lithium can be used in discharge, and the utilization rate can be further improved.

[0050] In the lithium primary battery 10, in order to prevent the end of the positive electrode 201, which is prone to cutting burrs of the core material of the current collector, from short-circuiting with the negative electrode 202, the positive electrode 201 is wound earlier than the negative electrode 202, and the positive electrode 201 exceeds the inner peripheral end of the negative electrode 202 and approaches the central axis 10AX. In this case, around the central axis 10AX, which is the winding start side of the electrode body 200, there is a portion of the positive electrode 201 that does not face the negative electrode 202 at the innermost periphery, and the positive electrode 201 is excessive relative to the negative electrode 202. As a result, discharge unevenness is likely to occur around the inner peripheral end of the winding start side of the negative electrode 202, and a lithium isolated region is likely to occur in the negative electrode 202 due to the disconnection of the negative electrode foil.

[0051] Therefore, in order to suppress the isolation (foil breaking) of lithium around the inner circumferential end of the winding start side of the negative electrode 202 and further improve the utilization rate of the negative electrode, it is preferred to configure a strip-shaped member on the inner circumferential surface (the surface facing the central axis 10AX of the winding body) of the first week including the inner circumferential end of the winding start side of the negative electrode 202.

[0052] The strip-shaped member may be arranged on the negative electrode 202 so as to extend substantially parallel to the winding direction Dw, or may be arranged so as to extend obliquely (or while being bent) relative to the winding direction Dw. However, in order to make the expansion of the outer diameter of the electrode body 200 generated by the provision of the strip-shaped member uniform and to suppress the discharge unevenness caused by the pressure applied to the negative electrode 202 changing in the central axis direction Da of the electrode body 200, the strip-shaped member may be arranged obliquely relative to the winding direction Dw. The strip-shaped member may extend from one end in the central axis direction Da of the electrode body 200 toward the other end in the negative electrode 202.

[0053] The strip-shaped member may include an insulating material or a conductive material. If the strip-shaped member is a conductive material, since the strip-shaped member itself acts as a current collector, the electrical connection between the lithium as the negative electrode 202 and the negative electrode lead 210 can be ensured even at the end of the discharge, and the reduction in discharge capacity can be further suppressed. When a conductive material is used as the strip-shaped member, the conductive material is preferably a stable material that is not accompanied by an electrochemical reaction at the potential of the negative electrode 202. From this point of view, it is preferred that lithium is substantially not included in the conductive material. The conductive material may include copper, for example.

[0054] The design energy density of the lithium primary battery 10 is 850Wh / L or more. The design energy density can be improved by increasing the amount of positive electrode active material carried on the battery 10. However, it is difficult to improve the actual energy density if the amount of lithium participating in the discharge in the negative electrode 202 is not increased correspondingly to the increase in the amount of positive electrode active material. From the perspective of achieving a high capacity of the lithium primary battery 10, it is important to increase the utilization rate of the negative electrode 202 to, for example, 85% or more while increasing the design energy density, thereby increasing the amount of lithium participating in the discharge in the negative electrode 202. If the design energy density is 850Wh / L or more, the effect of suppressing the breakage of the negative electrode 202 at the end of the discharge by adopting the structure of the electrode body 200 and the negative electrode lead 210 of the present invention is significant, and the effect of improving the utilization rate of the negative electrode can be effectively exerted.

[0055] In the lithium primary battery 10 according to one embodiment of the present invention, the negative electrode utilization rate may be 85% or more, 90% or more, or 94% or more.

[0056] The designed energy density is expressed by the following equation based on the positive electrode theoretical capacity calculated from the amount of positive electrode active material. The nominal voltage is 3V, for example.

[0057] (Designed energy density) = (positive electrode theoretical capacity) × (nominal voltage) / (volume of battery 10)

[0058] (Volume of the battery 10) = π × ((outer diameter d10 of the battery can 100) / 2) 2 × (maximum height h10 of the battery 10 based on the bottom 100B of the battery can 100 )

[0059] The positive electrode theoretical capacity is expressed by the following formula when the positive electrode active material is electrolytic manganese dioxide (MnO2).

[0060] (Positive electrode theoretical capacity) = (mass of MnO2 in the positive electrode mixture (mg)) × (theoretical capacity per 1mg of MnO2 (=0.308mAh / mg)) × (positive electrode utilization rate (=0.9))

[0061] The negative electrode utilization rate (%) is calculated by (C / N)×100 based on the discharge capacity C of the manufactured lithium primary battery 10 when discharged under the following discharge conditions and the amount of lithium taken out of the negative electrode of the manufactured lithium primary battery 10 and the negative electrode theoretical capacity N calculated from the amount of lithium.

[0062] (Discharge conditions)

[0063] The battery 10 was pre-discharged at room temperature (25° C.) for 162 seconds at a current of 2 A. Thereafter, the battery 10 was connected to a resistor of 1 kΩ and discharged to 2.0 V at a constant resistance.

[0064] The discharge capacity in the above 1 kΩ constant resistance discharge plus the discharge capacity in the pre-discharge (90 mAh) is defined as the discharge capacity C. The negative electrode theoretical capacity N can be obtained by multiplying the amount of lithium in the negative electrode (mg) by the theoretical capacity per 1 mg of lithium (=3.86 mAh / mg).

[0065] The negative electrode lead 210 covers a portion of the negative electrode 202 and is electrically connected to the negative electrode 202 (see Figure 2A , Figure 2B ). Figure 1B The positional relationship between the attachment position of the negative electrode lead 210 in the electrode body 200 and the outermost peripheral portion of the positive electrode 201 is shown.

[0066] The negative electrode 202 is wound more than two times, and the negative electrode lead 210 is not arranged at the innermost circumference of the negative electrode 202 and the outermost circumference of the negative electrode 202. That is, the center X of the protective tape 240 is between the position P1 wound one turn starting from the end P0 and the position Q1 in the direction Dc opposite to the winding direction Dw starting from the end Q0, and the end P0 is the inner circumferential end in the direction Dc on the winding start side of the negative electrode 202, and the end Q0 is the outer circumferential end on the winding end side of the negative electrode 202. This means that at the position X of the center of the protective tape 240, the negative electrode 202 exists on the outer circumferential side and the inner circumferential side relative to the position X.

[0067] like Figure 1B As shown, when the electrode body 200 is viewed from the winding center axis direction Da, a straight line connecting the center O (central axis 10AX) of the electrode body 200 and the center X of the protective tape 240 is drawn and is referred to as a straight line A. The position of the outer peripheral end of the positive electrode 201 at the winding end side is referred to as the positive electrode outer peripheral end position R. The positive electrode outer peripheral end position R is the position of the outer peripheral end at the winding end side where the positive electrode active material layer is formed in the positive electrode 201.

[0068] The end position of the protective tape 240 covering the negative electrode lead 210 in the winding direction Dw is denoted as Y. The end position of the protective tape 240 covering the negative electrode lead 210 on the opposite side of the winding direction is denoted as Z. A straight line passing through the position Y and parallel to the straight line A and a straight line passing through the position Z and parallel to the straight line A are drawn and denoted as straight line B and straight line C, respectively.

[0069] The position R of the positive electrode terminal is on the straight line A or near the straight line A. In this case, the excessive discharge reaction in the radial direction caused by the positive electrode terminal is suppressed, and the discharge reaction can be uniformly performed in the entire negative electrode 202. As a result, the foil breakage is suppressed and the utilization rate of the negative electrode 202 can be improved. The position R of the positive electrode terminal does not necessarily need to be on the straight line A. The position R of the positive electrode terminal only needs to be close to the straight line A to the extent that it is within the area sandwiched by the straight lines B and C.

[0070] like Figure 2A and Figure 2B As shown, a negative electrode lead 210 and a protective tape 240 are disposed on the negative electrode 202. The negative electrode lead 210 covers a portion of the negative electrode 202 and is electrically connected to the negative electrode 202. Figure 2A 2 is a diagram showing the arrangement layout of the negative electrode lead 210 and the protective tape 240 in the negative electrode 202 when the electrode body 200 is formed by winding, as viewed from the main surface (inner peripheral surface 202A) facing the inside. Figure 2B The diagram shows the arrangement layout of the negative electrode lead 210 and the protective tape 241 in the negative electrode 202 when the electrode body 200 is formed by winding, as viewed from the main surface (outer peripheral surface) facing outward.

[0071] The negative electrode 202 is in the shape of a rectangular strip with the winding direction Dw as the longitudinal direction, and has ends (first end E1 to fourth end E4) consisting of four sides. The winding direction Dw is set to be the direction from the third end E3 as the inner peripheral end on the winding start side to the fourth end E4 as the outer peripheral end on the winding end side. The central axis direction Da is the direction from the second end E2 to the first end E1. Figure 1A The negative electrode lead 210 is set to be in a direction from the bottom of the battery can 100 to the sealing plate 300. The negative electrode lead 210 is provided at a position (e.g., near the center) that is not located at the innermost circumference or the outermost circumference when winding in the winding direction Dw of the negative electrode 202. The negative electrode lead 210 includes a first portion 211 protruding from the first end E1 of the negative electrode 202, and a second portion 212 extending in a direction opposite to the protruding direction of the first portion 211 and covering the negative electrode 202.

[0072] In order to prevent short circuit, the second portion 212 of the negative electrode lead 210 is covered with the protective tape 240. Usually, as a margin for attaching the protective tape 240 to the negative electrode lead 210, a part of the negative electrode 202 adjacent to the second portion 212 is also covered with the protective tape 240. The width of the attached portion is, for example, 5 mm or less, and more preferably 3 mm or less, on the side (second end side) of the negative electrode lead 210 opposite to the protruding direction of the first portion.

[0073] like Figure 2AAs shown, on the inner circumference of the negative electrode 202, the protective tape 240 covers the second portion 212 and a portion of the negative electrode 202 adjacent to the second portion 212. On the other hand, on the outer circumference of the negative electrode 202, as shown in FIG. Figure 2B As shown, the protective tape 241 covers only the first portion 211 of the negative electrode lead 210, and does not cover the negative electrode 202. Thus, the protective tape is prevented from hindering the discharge reaction of the negative electrode 202 on the outer peripheral surface, and the utilization rate of the negative electrode 202 can be further improved.

[0074] However, the outer peripheral surface of the negative electrode 202 may also be Figure 2C , Figure 2D As shown in FIG. 1 , the protective tape 242 covers an area corresponding to the back side of the area of ​​the negative electrode 202 to which the second portion 212 is mounted. Figure 2A The guard band 242 is configured with the same layout.

[0075] Figure 3 This is a schematic diagram showing another example of the structure of the negative electrode 202 before winding used in the lithium primary battery 10 of the present embodiment, showing the arrangement layout of the negative electrode lead 210 and the protective tape 240 in the negative electrode 202 observed from the main surface (inner peripheral surface) facing the inside when the electrode body 200 is formed by winding. Figure 3 In the example of FIG. 1 , the strip-shaped member 250 is provided on the inner peripheral surface of the negative electrode 202 at a position which becomes the innermost peripheral portion of the winding start point.

[0076] The strip member 250 extends in an oblique direction with respect to the winding direction Dw on the inner peripheral surface of the negative electrode 202 so as to cross between a first end E1 where the first portion 211 of the negative lead 210 protrudes in the central axis direction Da and a second end E2 on the opposite side to the first end E1 . Figure 3 In the example, the strip member 250 extends obliquely from the third end E3 close to the second end E2 and the inner end at the winding start side toward the negative electrode lead 210 and the fourth end E4 as the outer end at the winding end side, approaching the first end E1.

[0077] The strip-shaped member 250 preferably extends from the third end E3 toward the negative electrode lead 210 and the fourth end E4 in at least the innermost region of the first cycle corresponding to the winding start side of the inner circumferential surface of the negative electrode 202. This can suppress the isolation (foil breakage) of lithium around the winding start side, i.e., the inner circumferential end, of the negative electrode 202, where discharge unevenness is particularly likely to occur, and further improve the negative electrode utilization rate.

[0078] In addition, by extending the strip-shaped member 250 obliquely, the change (i.e., expansion) of the outer diameter of the electrode body 200 in the central axis direction Da when the negative electrode 202 is wound together with the positive electrode 201 and the separator 203 to form the electrode body 200 is suppressed, and the pressure applied to the negative electrode 202 becomes uniform, so that the discharge unevenness caused by the change of the pressure applied to the negative electrode 202 in the central axis direction Da of the electrode body 200 is suppressed. As a result, the isolation (foil breakage) of lithium is suppressed, and the negative electrode utilization rate can be further improved.

[0079] The belt-shaped member 250 is not limited to Figure 3 For example, the strip-shaped member 250 may extend in an inclined manner from a position close to the first end E1 and the third end E3 as the inner peripheral end of the winding start side toward the negative electrode lead 210 and the fourth end E4 to approach the second end E2. In addition, the strip-shaped member 250 may extend along the winding direction Dw. However, if Figure 3 As shown in the figure, the strip-shaped member is extended obliquely so as to approach the first end E1 as it approaches the negative electrode lead 210 and the fourth end E4, so that the distance between the strip-shaped member and the protective tape becomes closer. The discharge reaction is difficult to proceed near the strip-shaped member and the protective tape, and lithium is likely to remain. Therefore, the remaining lithium can be used in the discharge at the end of the discharge, and the utilization rate of the negative electrode 202 can be improved.

[0080] The strip-shaped member is preferably arranged on the main surface (inner peripheral surface) of the inner peripheral side when the electrode body 200 is formed by winding among the two main surfaces of the negative electrode 202. The electrode body 200 expands with discharge, and the negative electrode 202 is subjected to the pressure accompanying the expansion. In the case where the strip-shaped member is on the surface (outer peripheral surface) on the outer peripheral side, the portion of the negative electrode 202 covered by the strip-shaped member is difficult to follow the expansion of the electrode body 200 because the movement in the radial direction is hindered by the strip-shaped member, and the pressure tends to increase. As a result, the discharge reaction is easy to proceed in the strip-shaped member and its vicinity, and the discharge is easy to be uneven, and it is easy to produce uneven lithium consumption. In contrast, in the case where the strip-shaped member is on the surface on the inner peripheral side, the portion of the negative electrode 202 covered by the strip-shaped member can move following the expansion of the electrode body 200 without being hindered by the strip-shaped member. As a result, the rise in pressure caused by the strip-shaped member is suppressed, and the situation where the discharge reaction is easy to proceed in the strip-shaped member and its vicinity can be suppressed. Thus, even at the end of discharge, the effect of ensuring electrical connection with the negative electrode lead 210 by the strip-shaped member can be fully exhibited.

[0081] (negative electrode)

[0082] Metal lithium and lithium alloy are used as negative electrode 202. Lithium alloy contains other metal elements besides lithium. As other metal elements, Al, Mg, Sn, Ni, Pb, In, Na, Ca, K, Fe, Si and the like can be cited. Lithium alloy can be an alloy containing one of these other metal elements, or an alloy with two or more metal elements. Lithium alloys can be, for example, Li-Al, Li-Sn, Li-NiSi, Li-Pb. These metal lithium and lithium alloys can be used directly as negative plates in a sheet-shaped state. Among lithium alloys, Li-Al alloy is preferred. Regarding the content of metal elements other than lithium contained in lithium alloys, it is preferably set to 0.05 to 15% by mass from the viewpoint of ensuring discharge capacity and stabilizing internal resistance. Metal lithium or lithium alloy can be formed into any shape and thickness according to the shape, size, specification performance and the like of the lithium primary battery 10.

[0083] (Strip member)

[0084] The belt-shaped member has a base material layer. The base material layer contains an insulating material or a conductive material.

[0085] The insulating material of the substrate layer may be a resin substrate. As the resin substrate, for example, polyimide, polyphenylene sulfide, polyether sulfone, polyolefins such as polyethylene and polypropylene, polyethylene terephthalate, etc. may be used. Among them, polyolefins are preferred, and polypropylene is more preferred. The insulating material may be a material formed by curing an insulating coating that is stable to the electrolyte, i.e., does not undergo physical and chemical changes due to the electrolyte.

[0086] The conductive material of the substrate layer may be a metal substrate. Thus, the strip-shaped member has conductivity and can replace the function of the collector of the negative electrode 202 even at the end of the discharge when lithium is exhausted. The metal substrate is not particularly limited, and examples thereof include metal foils such as copper foil. The conductive material may also be a material formed by curing a conductive coating that is stable to the electrolyte.

[0087] The strip-shaped member may further include an adhesive layer having adhesive properties in addition to the base layer. For example, the strip-shaped member may be a long tape having an adhesive layer formed on a base layer.

[0088] The adhesive layer, for example, comprises at least one component selected from a rubber component, a silicone component and an acrylic resin component. Specifically, synthetic rubber, natural rubber, etc. can be used as the rubber component. As the synthetic rubber, butyl rubber, butadiene rubber, styrene-butadiene rubber, isoprene rubber, chloroprene rubber, polyisobutylene, acrylonitrile-butadiene rubber, styrene-isoprene block copolymer, styrene-butadiene block copolymer, styrene-ethylene-butadiene block copolymer, etc. can be cited. As the silicone component, an organic compound with a polysiloxane structure, a silicone polymer, etc. can be used. As the silicone polymer, peroxide-cured silicone, addition reaction silicone, etc. can be cited. As the acrylic resin component, a polymer containing acrylic monomers such as acrylic acid, methacrylic acid, acrylic esters, and methacrylic esters can be used, and examples thereof include homopolymers or copolymers of acrylic monomers such as acrylic acid, methacrylic acid, methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, propyl acrylate, propyl methacrylate, butyl acrylate, butyl methacrylate, octyl acrylate, octyl methacrylate, 2-ethylhexyl acrylate, and 2-ethylhexyl methacrylate. It should be noted that the adhesive layer may also contain a crosslinking agent, a plasticizer, and a tackifier.

[0089] The width W of the strip-shaped member may be 0.5 mm or more, and is preferably 1 mm or more, and more preferably 1.5 mm or more, from the viewpoint of appropriately suppressing the discharge consumption of lithium covered by the strip-shaped member and ensuring the electrical connection between the lithium and the negative electrode lead 210. The width W of the strip-shaped member may be 5 mm or less, but is preferably 3 mm or less, and more preferably 2.5 mm or less, from the viewpoint of sufficiently suppressing the reduction in the discharge capacity (output capacity) of the battery 10.

[0090] (positive electrode)

[0091] The positive electrode active material contains at least one selected from manganese oxide and graphite fluoride. Manganese dioxide can be used alone as the positive electrode active material, or it can be used in combination with manganese oxide, graphite fluoride, etc. The battery containing manganese dioxide shows a higher voltage and excellent pulse discharge characteristics. It is preferred to use electrolytic manganese dioxide that has been neutralized with ammonia, sodium hydroxide, lithium hydroxide, etc. as manganese dioxide. It is more preferred to use calcined electrolytic manganese dioxide that has been calcined. Specifically, it is preferred to calcine the electrolytic manganese dioxide in air or oxygen at 300 to 450°C for about 6 to 12 hours. The oxidation number of manganese contained in manganese dioxide is 4 in representative cases, but it is not limited to 4, and a slight reduction is allowed. As manganese oxides that can be used, MnO, Mn3O4, Mn2O3, MnO2, etc. can be cited, and manganese dioxide is usually used as the main component. Manganese dioxide can also be a mixed crystal state containing multiple crystal states. When uncalcined electrolytic manganese dioxide is used, it is preferred that the crystallinity of the manganese dioxide be increased by the conditions during electrolytic synthesis to reduce the specific surface area. In addition, chemical manganese dioxide or the like may be added in a small amount.

[0092] The positive electrode 201 includes a positive electrode mixture layer containing a positive electrode active material and a positive electrode collector to which the positive electrode mixture layer is attached. The positive electrode mixture layer is formed, for example, by embedding the positive electrode collector on one or both sides of a sheet-like positive electrode collector (e.g., expanded metal, mesh, punched metal, etc. made of stainless steel). For example, stainless steel, aluminum, titanium, etc. can be used as the positive electrode collector. The positive electrode mixture layer can contain a resin material such as a fluororesin as a binder in addition to the positive electrode active material. The positive electrode mixture layer can contain a conductive material such as a carbon material as a conductive agent.

[0093] For example, fluororesins, rubber particles, acrylic resins, etc. can be used as binders. Polytetrafluoroethylene, tetrafluoroethylene-hexafluoropropylene copolymers, and polyvinylidene fluoride can be used as fluororesins. Styrene butadiene rubber (SBR) and modified acrylonitrile rubber can be used as rubber particles. As acrylic resins, ethylene-acrylic acid copolymers can be mentioned. The amount of binder contained in the positive electrode mixture is more preferably 1 to 10% by mass, more preferably 2 to 8% by mass, and more preferably 3 to 7% by mass. The binder can be used alone or in combination of two or more.

[0094] For example, natural graphite, artificial graphite, carbon black, carbon fiber, etc. can be used as the conductive agent. As carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, thermal black, etc. can be mentioned. They can be used alone or in combination of two or more. The amount of the conductive agent contained in the positive electrode mixture is, for example, 1 to 30 parts by mass per 100 parts by mass of the positive electrode active material.

[0095] The positive electrode 201 is produced, for example, as follows.

[0096] First, manganese dioxide, a conductive agent, and a binder are mixed to prepare a positive electrode mixture. The mixing method of manganese dioxide, a conductive agent, and a binder is not particularly limited. For example, manganese dioxide, a conductive agent, and a binder are mixed in a dry or wet manner, and the resulting mixture is filled in a stainless steel mesh metal of a collector, and after being pressed with a roller, it is cut into a specified size to obtain a positive electrode 201.

[0097] (Spacer)

[0098] In order to make the electrolyte 204 easy to penetrate, it is preferred to use a porous sheet formed of an insulating material that is resistant to the internal environment of the lithium primary battery 10 as the separator 203. Specifically, non-woven fabrics made of synthetic resins, microporous films made of synthetic resins, etc. can be cited. As synthetic resins used in non-woven fabrics, for example, polypropylene, polyphenylene sulfide, polybutylene terephthalate, etc. can be cited. Among them, polyphenylene sulfide and polybutylene terephthalate have excellent high temperature resistance, solvent resistance and liquid retention. As synthetic resins used in microporous films, for example, polyolefin resins such as polyethylene, polypropylene, and ethylene-propylene copolymers can be cited. The microporous film can contain inorganic particles as needed. The thickness of the separator 203 is preferably, for example, 5 μm or more and 100 μm or less.

[0099] (Non-aqueous electrolyte)

[0100] The non-aqueous electrolyte 204 uses a substance in which a lithium salt is dissolved as a solute in a non-aqueous solvent. An additive may be included as needed. The non-aqueous solvent may use an organic solvent that can be generally used in the non-aqueous electrolyte 204 of a lithium primary battery, such as dimethyl ether, γ-butyrolactone, propylene carbonate, ethylene carbonate, 1,2-dimethoxyethane, etc. They may be used alone or in combination of two or more. From the viewpoint of improving the discharge characteristics of a lithium primary battery, the non-aqueous solvent preferably includes a cyclic carbonate with a high boiling point and a chain ether with a low viscosity even at low temperatures. The cyclic carbonate preferably includes at least one selected from propylene carbonate (PC) and ethylene carbonate (EC), and PC is particularly preferred. The chain ether preferably has a viscosity of 1 mPa·s or less at 25°C, and dimethoxyethane (DME) is particularly preferred. Here, the viscosity of the non-aqueous solvent can be determined using a micro-sample viscometer m-VROC manufactured by RheoSense at a temperature of 25°C using a shear rate of 10000 (1 / s).

[0101] The solute may include lithium salts such as LiCF3SO3, LiClO4, LiBF4, LiPF6, LiRaSO3 (Ra is a fluorinated alkyl group having 1 to 4 carbon atoms), LiFSO3, LiN(SO2Rb)(SO2Rc) (Rb and Rc are each independently a fluorinated alkyl group having 1 to 4 carbon atoms), LiN(FSO2)2, and LiPO2F2. They may be used alone or in combination of two or more. The total concentration of the lithium salts contained in the non-aqueous electrolyte 204 is preferably 0.2 to 2.0 mol / L, 0.3 to 1.5 mol / L, or 0.4 to 1.2 mol / L.

[0102] The non-aqueous electrolyte 204 may contain additives such as propane sultone and vinylene carbonate in addition to the materials already described. A portion of the hydrogen groups of the additives may be replaced by hydroxyl groups, halogen groups, alkyl groups, etc. The additives may be used alone or in combination of two or more. The total concentration of the additives contained in the non-aqueous electrolyte 204 is preferably 0.003 to 5 mol / L, more preferably 0.003 to 3 mol / L.

[0103] Hereinafter, the present invention will be specifically described based on Examples and Comparative Examples; however, the present invention is not limited to the following Examples.

[0104] 《Example 1》

[0105] (1) Preparation of positive electrode

[0106] A positive electrode mixture was prepared by mixing 92 parts by mass of electrolytic manganese dioxide as a positive electrode active material, 3 parts by mass of Ketjen black as a conductive agent, and 5 parts by mass of polytetrafluoroethylene as a binder.

[0107] Then, a drawn metal is made from ferritic stainless steel (SUS444) with a thickness of 0.1 mm to prepare a positive electrode collector. Then, two groups of rollers are prepared, each consisting of two rollers forming a pair. A positive electrode mixture is put between a pair of rollers for each group to obtain a sheet of the positive electrode mixture. The two sheets of the obtained positive electrode mixture are crimped from both sides through the drawn metal and dried to obtain a positive electrode precursor. Thereafter, another pair of rollers are used to roll the sheet to a thickness of 0.63 mm, and the sheet is cut into a specified size (width 42 mm, length 185 mm) to obtain a positive electrode plate. The positive electrode mixture is peeled off from a portion of the positive electrode plate to expose the positive electrode collector, and the positive electrode lead is welded to the exposed portion. A lead protection tape is affixed to the upper portion of the positive electrode lead for the purpose of preventing short circuits.

[0108] (2) Preparation of negative electrode

[0109] A metal lithium plate with a thickness of 0.3 mm was cut into a specified size (width 41 mm, length 153 mm) and used as a negative electrode plate. In order to measure the utilization rate of the negative electrode, the weight of the negative electrode plate was measured. A negative electrode lead 210 made of nickel was connected to the negative electrode plate. Protective tapes 240 and 242 for the purpose of preventing short circuits were pasted in a manner that covers both sides of the protruding portion (first portion) of the negative electrode lead 210 from the negative electrode and the connecting portion (second portion) with the negative electrode. For the protective tapes 240 and 242, the pasted portion was set in a manner that exceeds the second portion and covers a portion of the negative electrode 202. In this way, the negative electrode 202 is provided on both sides as shown in FIG. Figure 2A Anode 202 is shown configured with guard bands 240 , 242 .

[0110] (3) Preparation of electrolyte

[0111] Propylene carbonate (PC), ethylene carbonate (EC) and 1,2-dimethoxyethane (DME) were mixed in a volume ratio of 2:1:2, and lithium trifluoromethanesulfonate (LiCF3SO3) was dissolved as a lithium salt in a concentration of 0.5 mol / L in the obtained non-aqueous solvent to prepare an electrolyte 204.

[0112] (4) Preparation of electrode body

[0113] The positive electrode mixture is peeled off from a part of the positive electrode 201 to expose the positive electrode collector, and a positive electrode terminal lead made of stainless steel is welded to the exposed part. The positive electrode 201 and the negative electrode 202 are wound into a spiral shape with a separator 203 of 25 μm in thickness sandwiched between them to form a columnar electrode body 200 (diameter 16 mm, inner diameter 4 mm). A polyethylene microporous film is used as the separator 203. In the electrode body 200, the negative electrode 202 is wound 5 times, and a negative electrode lead 210 is arranged at the position of the third week from the inner circumferential end as the starting side of the winding. In addition, the electrode body 200 is formed in a manner that satisfies the above-mentioned condition (II).

[0114] (5) Assembly of cylindrical batteries

[0115] The obtained electrode body 200 is inserted into a bottomed cylindrical battery can with a ring-shaped lower insulating plate disposed at its bottom. The upper insulating plate is disposed on the electrode body 200, and then the negative electrode lead 210 connected to the negative electrode 202 is connected to the inner surface of the sealing plate, and the positive electrode lead connected to the positive electrode collector of the positive electrode 201 is connected to the inner bottom surface of the battery can.

[0116] Then, the non-aqueous electrolyte 204 is injected into the interior of the battery can, and thereafter, a sealing plate is inserted near the opening of the battery can, and the opening end of the battery can and the peripheral edge of the sealing plate are laser welded to complete a cylindrical lithium primary battery with a diameter of 17.4 mm and a height of 50.5 mm. The theoretical capacity of this battery is determined by the positive electrode 201, and the design energy density calculated based on the positive electrode theoretical capacity calculated based on the feeding amount of manganese dioxide as the positive electrode active material is 902Wh / L.

[0117] Make 5 of them like this Figure 1A A sealed cylindrical lithium primary battery A1 of the structure shown.

[0118] [evaluate]

[0119] The prepared battery was discharged at a constant current of 2A for 162 seconds at 25°C to perform a pre-discharge of about 90 mAh. Thereafter, the battery was subjected to a constant resistance discharge (1 kΩ) to measure the discharge capacity until 2.0 V. The ratio of the sum of the pre-discharge capacity and the discharge capacity until 2.0 V to the theoretical capacity determined based on the amount of the negative electrode active material of the negative electrode 202 was calculated, and the average of 5 values ​​was calculated as the negative electrode utilization rate.

[0120] 《Example 2》

[0121] Cylindrical lithium primary batteries A2 with a designed energy density of 850 Wh / L were obtained in the same manner as in Example 1 except that the amount of manganese dioxide charged as the positive electrode active material was changed. Five cylindrical lithium primary batteries A2 were produced and the negative electrode utilization was evaluated in the same manner.

[0122] 《Example 3》

[0123] The connection position of the negative electrode lead 210 in the negative electrode was changed in Example 1. The negative electrode lead 210 was arranged at the second position from the innermost circumference on the winding start side in the electrode body 200. However, similarly to Example 1, the electrode body 200 was formed to satisfy the above condition (II).

[0124] Five cylindrical lithium primary batteries A3 were produced in the same manner as in Example 1, and the negative electrode utilization rate was evaluated in the same manner.

[0125] 《Example 4》

[0126] In Example 1, the number of windings of the negative electrode in the preparation of the electrode body 200 was changed from 5 to 3. Along with this, the thickness and length of the positive and negative electrodes were changed in the same manner as in Example 1 so that the amount of the positive and negative electrode active materials was the same. The positive electrode 201 was set to have a thickness of 0.95 mm and a length of 122 mm, and the negative electrode was set to have a thickness of 0.46 mm and a length of 100 mm. The electrode body 200 was formed so that the negative electrode lead 210 was arranged at the position of the second week from the inner circumferential end as the winding start side, and the above-mentioned condition (II) was satisfied.

[0127] Five cylindrical lithium primary batteries A4 were produced in the same manner as in Example 1, and the negative electrode utilization rate was evaluated in the same manner.

[0128] 《Example 5》

[0129] In Example 1, the number of windings of the negative electrode in the preparation of the electrode body 200 was changed from 5 to 6. Along with this, the thickness and length of the positive and negative electrodes were changed in the same manner as in Example 1 so that the amount of the positive and negative electrode active materials was the same. The positive electrode 201 was set to have a thickness of 0.54 mm and a length of 214 mm, and the negative electrode was set to have a thickness of 0.25 mm and a length of 183 mm. The electrode body 200 was formed so that the negative electrode lead 210 was arranged at the position of the 4th week from the inner circumferential end as the winding start side, and the above-mentioned condition (II) was satisfied.

[0130] Five cylindrical lithium primary batteries A5 were produced in the same manner as in Example 1, and the negative electrode utilization rate was evaluated in the same manner.

[0131] Example 6

[0132] In Example 1, the number of windings of the negative electrode in the preparation of the electrode body 200 was changed from 5 to 6. Along with this, the thickness and length of the positive and negative electrodes were changed in the same manner as in Example 1 so that the amount of the positive and negative electrode active materials was the same. The positive electrode 201 was set to have a thickness of 0.54 mm and a length of 214 mm, and the negative electrode was set to have a thickness of 0.25 mm and a length of 183 mm. The electrode body 200 was formed so that the negative electrode lead 210 was arranged at the position of the second week from the inner circumferential end as the winding start side, and the above-mentioned condition (II) was satisfied.

[0133] Five cylindrical lithium primary batteries A6 were produced in the same manner as in Example 1, and the negative electrode utilization rate was evaluated in the same manner.

[0134] Example 7

[0135] In the production of the negative electrode, a 2 mm wide tape is attached as a strip-shaped member to the innermost area of ​​the inner circumference of the negative electrode, which constitutes the first cycle of winding. The resin base material of the tape is made of polypropylene, and the main component of the adhesive layer is rubber. The tape is arranged so as to be inclined from the second end E2 on the opposite side of the first end from which the electrode lead protrudes toward the first end E1 as it approaches the negative electrode lead 210 and the fourth end E4 from the position close to the third end E3, which is the inner circumference end of the winding start side. Thus, the inner circumference of the negative electrode, which becomes the inner side of the winding, is obtained. Figure 3 A negative electrode in which the protective tape and the strip-shaped member are arranged as shown, and the protective tape is arranged on the outer peripheral surface of the negative electrode which becomes the outer side of the winding in the same manner as in Example 1.

[0136] Using the negative electrode obtained in this manner, five cylindrical lithium primary batteries A7 were produced in the same manner as in Example 1, and the negative electrode utilization rate was evaluated in the same manner.

[0137] 《Example 8》

[0138] In the manufacture of the negative electrode, the area where the protective tape is installed is changed, and on the outer circumference of the negative electrode, the protective tape 241 only covers the protruding portion (the first portion) of the negative electrode lead 210 from the negative electrode, and does not cover the connection portion (the second portion) with the negative electrode. In addition, the same method as in Example 7 is used to obtain the inner circumference of the negative electrode that becomes the inner side of the winding. Figure 3 As shown in FIG. 1 , a protective tape and a strip-shaped member are arranged, and the outer peripheral surface of the negative electrode that becomes the outer side of the winding is as shown in FIG. Figure 2B A negative electrode with a guard band is shown.

[0139] In addition, in the production of the positive electrode 201 , the amount of manganese dioxide charged as the positive electrode active material was changed to change the designed energy density to 930 Wh / L.

[0140] Using the positive electrode 201 and the negative electrode obtained in this manner, five cylindrical lithium primary batteries A8 were produced in the same manner as in Example 1, and the negative electrode utilization rate was evaluated in the same manner.

[0141] Comparative Example 1

[0142] The connection position of the negative electrode lead in the negative electrode was changed in Example 1. In the electrode body, the negative electrode lead was arranged at the third turn from the winding start side. However, the electrode body was formed so as not to satisfy the above condition (II).

[0143] Five cylindrical lithium primary batteries B1 were produced in the same manner as in Example 1, and the negative electrode utilization rate was evaluated in the same manner.

[0144] Comparative Example 2

[0145] In Comparative Example 1, the amount of manganese dioxide as the positive electrode active material was changed, and the cylindrical lithium primary battery B2 with a designed energy density of 850Wh / L was obtained in the same manner as in Comparative Example 1. Five cylindrical lithium primary batteries B2 were produced, and the negative electrode utilization was evaluated in the same manner.

[0146] 《Comparative Example 3》

[0147] Cylindrical lithium primary battery B3 with a designed energy density of 700Wh / L was obtained in the same manner as in Example 1 except that the amount of manganese dioxide charged as the positive electrode active material was changed. Five cylindrical lithium primary batteries B3 were produced and the negative electrode utilization was evaluated in the same manner.

[0148] 《Comparative Example 4》

[0149] In Comparative Example 1, the amount of manganese dioxide as the positive electrode active material was changed, and the cylindrical lithium primary battery B4 with a designed energy density of 700Wh / L was obtained in the same manner as in Comparative Example 1. Five cylindrical lithium primary batteries B4 were produced, and the negative electrode utilization was evaluated in the same manner.

[0150] 《Comparative Example 5》

[0151] The connection position of the negative electrode lead in the negative electrode was changed in Example 1. The negative electrode lead was arranged at the outermost position of the fifth turn from the winding start side in the electrode body. However, as in Example 1, the electrode body was formed to satisfy the above-mentioned condition (II).

[0152] Five cylindrical lithium primary batteries B5 were produced in the same manner as in Example 1, and the negative electrode utilization rate was evaluated in the same manner.

[0153] 《Comparative Example 6》

[0154] The connection position of the negative electrode lead in the negative electrode was changed in Example 1. The negative electrode lead was arranged at the outermost position of the fifth turn from the winding start side in the electrode body. In addition, the electrode body was formed so as not to satisfy the above-mentioned condition (II).

[0155] Five cylindrical lithium primary batteries B6 were produced in the same manner as in Example 1, and the negative electrode utilization rate was evaluated in the same manner.

[0156] 《Comparative Example 7》

[0157] The connection position of the negative electrode lead in the negative electrode was changed in Example 1. The negative electrode lead was arranged at the innermost position of the first circle from the winding start side in the electrode body. However, as in Example 1, the electrode body was formed to satisfy the above-mentioned condition (II).

[0158] Five cylindrical lithium primary batteries B7 were produced in the same manner as in Example 1, and the negative electrode utilization rate was evaluated in the same manner.

[0159] 《Comparative Example 8》

[0160] The connection position of the negative electrode lead in the negative electrode was changed in Example 1. The negative electrode lead was arranged at the innermost position of the first turn from the winding start side in the electrode body. In addition, the electrode body was formed so as not to satisfy the above-mentioned condition (II).

[0161] Five cylindrical lithium primary batteries B8 were produced in the same manner as in Example 1, and the negative electrode utilization rate was evaluated in the same manner.

[0162] In each of the batteries of Examples 1 to 8 and Comparative Examples 1 to 8, the charged capacity of the negative electrode was the same.

[0163] Figure 4 The evaluation results of the negative electrode utilization are shown in FIG. Figure 4 The design energy density of each battery, the discharge capacity measured in the evaluation of the negative electrode utilization rate, whether conditions (I) and (II) are satisfied, the number of windings of the negative electrode, the position of the negative electrode lead, the presence or absence of a strip member, and the state of the protective tape on the outer peripheral surface of the negative electrode are also shown. Figure 4 In the figure, the position of the negative electrode lead is shown in which number of times from the inner circumferential end, which is the winding start side, the negative electrode lead is arranged. Figure 2A In the case where the protective tape covers the connection portion (part 2) of the negative electrode lead and the negative electrode, it is referred to as "covering". Figure 2B When the protective tape covers only the protruding portion of the negative electrode lead from the negative electrode and does not cover the second portion, it is described as “exposed”.

[0164] Reference Figure 4 Comparing batteries B3 and B4, when the design energy density is set to 700Wh / L, no significant difference is observed in the negative electrode utilization rate depending on whether condition (II) is met. In addition, the negative electrode utilization rate is as low as about 73%.

[0165] In batteries B1 and B2, the designed energy density is increased to 902Wh / L or 850Wh / L due to the increase in the amount of positive electrode active material compared to battery B4. At this time, since the amount of lithium as the negative electrode active material has not changed, it can be expected that the negative electrode utilization rate will increase as the designed energy density is increased. For example, compared to the negative electrode utilization rate of battery B4 of 73.4%, the negative electrode utilization rate of battery B1 should theoretically be increased to about 73.4×(902 / 700)=94.6%, but the actual evaluation result is about 75%, and the negative electrode utilization rate has only increased slightly. Therefore, the capacity has only increased slightly relative to the designed energy density.

[0166] In addition, when condition (II) is satisfied but condition (I) is not satisfied, the negative electrode utilization rate of battery B5 in which the negative electrode lead is arranged at the outermost circumference of the negative electrode and battery B7 in which the negative electrode lead is arranged at the innermost circumference of the negative electrode is only slightly increased relative to battery B3. When both conditions (I) and (II) are not satisfied, the negative electrode utilization rate of battery B6 in which the negative electrode lead is arranged at the outermost circumference of the negative electrode and battery B8 in which the negative electrode lead is arranged at the innermost circumference of the negative electrode is reduced relative to battery B4.

[0167] In contrast, in batteries A1 to A8 satisfying conditions (I) and (II), a high negative electrode utilization rate of 85% or more can be achieved while increasing the design energy density to 850Wh / L or more. In addition, in battery A7 in which a strip-shaped member is arranged in the region constituting the first winding cycle of the inner circumference of the negative electrode, and in battery A8 in which, in addition to the strip-shaped member, a protective tape is provided on the outer circumference of the negative electrode to cover only the protruding portion of the negative electrode lead from the negative electrode, and the negative electrode is exposed on the outer circumference, significantly high negative electrode utilization rates can be achieved.

[0168] Industrial Applicability

[0169] The lithium primary battery of the present invention is suitable for use in long-term driving of equipment. The lithium primary battery of the present invention can be applied to, for example, meters for gas, tap water, and the like.

[0170] Description of Reference Numerals

[0171] 10 Lithium primary battery

[0172] 100 Battery Cans

[0173] 100A battery tank barrel

[0174] 100A1 Battery can opening

[0175] 100A2 Opening on the opposite side of the battery can

[0176] 100B Seal the bottom of the battery tank

[0177] 200 Electrode body

[0178] 201 Positive electrode

[0179] 202 Negative electrode

[0180] 202A Inner surface of negative electrode

[0181] 202B Negative electrode outer surface

[0182] 203 Spacer

[0183] 204 Electrolytes

[0184] 210 Internal lead (negative lead)

[0185] 210A Inner surface of the inner lead (negative lead)

[0186] 210B Outer surface of inner lead (negative lead)

[0187] 211 Part 1

[0188] 212 Part 2

[0189] 220 Internal lead (positive lead)

[0190] 230A Upper insulation plate

[0191] 230B Lower insulation board

[0192] 240 A protective tape covering the inner peripheral surface 210A of the negative electrode lead and also covering the inner peripheral surface 202A of the negative electrode

[0193] 241 A protective tape covering the outer peripheral surface 210B of the negative electrode lead and exposing the outer peripheral surface 202B of the negative electrode

[0194] 242 Protective tape covering the outer peripheral surface 210B of the negative electrode lead and also covering the outer peripheral surface 202B of the negative electrode

[0195] 250 Strip components

[0196] 300 Sealing plate

[0197] 310 Insulating gasket

[0198] 330 external terminal

Claims

1. A lithium primary battery having: An electrode body comprising a positive electrode, a negative electrode and a separator, wherein the positive electrode and the negative electrode are stacked with the separator interposed therebetween in a manner that the negative electrode has a first surface facing the positive electrode and is spirally wound around a central axis; a negative electrode lead attached to the first surface of the negative electrode so as to cover a portion of the first surface of the negative electrode and be electrically connected to the negative electrode; and a protective tape covering a portion of the negative electrode lead and being wider than the negative electrode lead, The outermost periphery of the electrode body is the positive electrode, In the electrode body, the negative electrode is wound more than 2 times, The negative electrode lead is not arranged at the innermost circumference of the negative electrode and the outermost circumference of the negative electrode, In a cross section perpendicular to the central axis of the electrode body, a first straight line connecting the central axis and the center of the protective tape, a second straight line passing through one end of the protective tape and parallel to the first straight line, and a third straight line passing through the other end of the protective tape and parallel to the first straight line are defined, and the outermost peripheral end of the positive electrode is located in a region sandwiched by the second straight line and the third straight line. The protective band is located between the end of the outer circumference of the positive electrode and the central axis, The designed energy density of the lithium primary battery is above 850Wh / L.

2. The lithium primary battery according to claim 1, wherein: The negative electrode further has a second surface opposite to the first surface, A portion of the second surface of the negative electrode, which is opposite to a portion of the first surface of the negative electrode to which the negative electrode lead is attached, is not covered with a protective tape.

3. The lithium primary battery according to claim 1 or 2, further comprising a belt-shaped member interposed between the negative electrode and the separator so as to cover a portion of the negative electrode, The belt-shaped member is disposed on the inner peripheral surface of the innermost periphery of the negative electrode.

4. The lithium primary battery according to claim 1 or 2, wherein: The negative electrode utilization rate of the negative electrode is above 85%.

Images