JP2004087324A - Nonaqueous electrolyte battery and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress reduction in battery properties and enhance manufacturing yield. <P>SOLUTION: A nonaqueous electrolyte battery has a battery element 2 in which a positive electrode 5 and a negative electrode 6 are wound in a length direction via a separator 7 and has a positive electrode collector exposing portion 11 and a negative electrode collector exposing portion 15 exposed, respectively, in a winding direction within a range from 10 mm to 100 mm near a winding center of the battery element 2. Consequently, the exposing portion 15 diffuses Joule heat caused when a current is flown out and suppresses the reduction in the battery properties. A positive electrode terminal 10 and a negative electrode terminal 14 are drawn out from positions at which center angles, which the electrode terminals 10, 14 form mutually with the winding center of the battery element 2, become about 120° or 240° in a winding axis direction of the battery element 2. Accordingly, roundness of an outer diameter of the battery element 2 is enhanced and the battery manufacturing yield is enhanced by inserting smoothly the battery element 2 into an exterior can 3. <P>COPYRIGHT: (C)2004,JPO

Description

【００９５】
なお、サンプル１及びサンプル３においては、充放電を以下のようにして行った。充電する際は、電池に対し、充電電流値３Ａ、上限電圧４．２Ｖの定電流定電圧充電を３時間行った。一方、放電する際は、６Ａの電流値で３Ｖまでの定電流放電を行った。そして、このような充放電条件で充放電を２００回繰り返し、２００サイクル目の放電容量維持率、すなわち初回放電容量に対する２００回目の放電容量の比率を測定した。
【００９６】
表１に示す評価結果から、電池素子の内周側において、長さが７０ｍｍの正極集電体露出部と、長さが４０ｍｍの負極集電体露出部とを対向させたサンプル１では、電池素子の内周側において、長さが４０ｍｍの正極集電体露出部と、長さが５ｍｍの負極集電体露出部とを対向させたサンプル３に比べ、重負荷充放電による２００サイクル目の放電容量維持率が大きくなっていることがわかる。
【００９７】
サンプル３では、特に電池素子の内周側の負極集電体露出部の長さが５ｍｍと短く、大電流が流れた際に正極側で発生するジュール熱を負極集電体露出部に適切に伝播させることできず、電池内部の熱を外部に拡散させることが困難となる。このため、サンプル３では、電流密度が大きな電池素子の捲回中心付近で大きなジュール熱を発生し、蓄熱されることから、特に電池素子の捲回中心付近で熱集中による電極の劣化が起こり電池特性も低下していってしまう。
【００９８】
一方、サンプル１では、電池素子の内周側の正極集電体露出部及び負極集電体露出部が適宜な長さであり、特に負極集電体露出部が４０ｍｍとなっていることから、大電流が流れた際に正極側で発生するジュール熱が負極集電体露出部に適切に伝播され、電池内部の熱を外部に容易に拡散させることができる。したがって、サンプル１では、大電流により発生したジュール熱が電池内部に蓄熱されることが抑えられ、熱による電極の劣化も抑制されることから、サンプル３に比べて優れた電池特性が得られる。
【００９９】
ここで、サンプル１及びサンプル３において、上述した放電条件で放電した際の電池素子中心及び電池外周面の温度変化を測定した。そして、サンプル１及びサンプル３における大電流で放電した際の温度変化の測定結果を図４に示す。なお、図４は、サンプル１及びサンプル３における放電時間と温度変化との関係を示す特性図である。
【０１００】
図４に示す評価結果から、サンプル１では、電池素子中心で温度が低く、電池外周面で温度が高くなっている。これに対し、サンプル３では、電池素子中心で温度が高く、電池外周面で温度が低くなっている。
【０１０１】
このことからも、サンプル１が電池内部にジュール熱が蓄熱されることを抑え、外部に熱を拡散させ易い構造であり、サンプル３が電池内部にジュール熱を蓄熱させ、外部に熱を拡散させることが困難な構造であることがわかる。
【０１０２】
以上のことから、電池を作製する際に、長さが７０ｍｍの正極集電体露出部と、長さが４０ｍｍの負極集電体露出部とを電池素子の捲回中心付近で対向させることは、重負荷充放電による２００サイクル目の放電容量維持率が優れた電池を作製する上で大変有効であることがわかる。
【０１０３】
次に、サンプル１及びサンプル２、サンプル４〜サンプル１３の電池について、電池素子の最大直径を測定し、電池素子を外装缶に収納する際の素子挿入不良率を調査した。
【０１０４】
以下、サンプル１及びサンプル２、サンプル４〜サンプル１３における、電池素子の最大直径と、電池素子挿入不良率とを表２に示す。
【０１０５】
【表２】

【０１０６】
表２に示す評価結果から、正極端子及び負極端子が、電池素子において、捲回中心に対して互いになす中心角が１２０°又は２４０°となる位置から捲回軸方向に引き出されているサンプル１及びサンプル２では、正極端子及び負極端子が、でんちそしにおいて、捲回中心に対して互いになす中心角が１２０°又は２４０°以外となる位置から捲回軸方向に引き出されているサンプル４〜サンプル１３に比べ、電池素子の最大直径が小さく、電池素子挿入不良率が低いことがわかる。
【０１０７】
サンプル４〜サンプル１３では、正極端子及び負極端子が、電池素子の捲回中心に対して互いになす中心角が１２０°又は２４０°以外となる位置から引き出されており、電池素子の外径の真円度が低くなって電池素子の最大直径が大きくなってしまう。このため、サンプル４〜サンプル１３では、外装缶に電池素子を挿入しにくくなり、外装缶の開口部の周縁部等に電池素子が当たってセパレータ等が破れるといった不良がたくさん生じる。
【０１０８】
一方、サンプル１及びサンプル２では、正極端子及び負極端子が、電池素子の捲回中心に対して互いになす中心角が１２０°又は２４０°となる位置から引き出されており、電池素子の外径の真円度が高くなって電池素子の最大直径が小さくなる。このため、サンプル１及びサンプル２では、外装缶に電池素子を円滑に挿入できることから、サンプル４〜サンプル１３よりも電池素子挿入不良の発生が抑制され、製造歩留まりの向上を図れる。
【０１０９】
以上のことから、電池を作製する際に、正極端子及び負極端子を、電池素子の捲回中心に対して互いになす中心角が１２０°又は２４０°となる位置から捲回軸方向に引き出すことは、電池素子の最大直径が小さくなって電池素子を外装缶に挿入する際の挿入不良率が低くなり、電池作製時の歩留まりを向上させる上で大変有効であることがわかる。
【０１１０】
【発明の効果】
以上の説明から明らかなように、本発明によれば、捲回構造の電池素子内周側の正極端部及び負極端部に、所定の範囲で正極集電体露出部及び負極集電体露出部を設けることにより、大電流により発生するジュール熱が電池素子の捲回中心付近に熱集中して起こる電極の劣化が抑制されることから、電池特性の低下が抑制された非水電解質電池が得られる。
【０１１１】
また、本発明によれば、正極端子及び負極端子が、電池素子の捲回中心に対して互いになす中心角が略１２０°又は略２４０°となる位置から電池素子の捲回軸方向に引き出されることにより、電池素子の外径の真円度が高まり、外装缶に電池素子を円滑に挿入できることから、電池作製時の歩留まりを向上させることができる。
【図面の簡単な説明】
【図１】本発明を適用したリチウムイオン二次電池の内部構造を示す縦断面図である。
【図２】同リチウムイオン二次電池の内部構造を横断面から示す模式図である。
【図３】同リチウムイオン二次電池における正極端子及び負極端子の取り付け位置を示す電池素子を捲回軸方向から見た概略側面図であり、同図（ａ）は電池素子の捲回中心に対して正極端子と負極端子とがなす中心角が１２０°である状態を示し、同図（ｂ）は電池素子の捲回中心に対して正極端子と負極端子とがなす中心角が２４０°である状態を示している。
【図４】サンプル１及びサンプル３における放電時間と電池温度との関係を示す特性図である。
【図５】従来のリチウムイオン二次電池の内部構造を横断面から示す模式図である。
【符号の説明】
１　リチウムイオン二次電池、２　電池素子、３　外装缶、４　非水電解液、５　正極、６　負極、７　セパレータ、８　正極集電体、９　正極合剤層、１０正極端子、１１　正極集電体露出部、１２　負極集電体、１３　負極合剤層、１４　負極端子、１５　負極集電体露出部、１６　負極片面合剤部[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a nonaqueous electrolyte battery including a battery element in which a positive electrode and a negative electrode are wound with a separator interposed therebetween, and having significantly improved battery characteristics, and a method for manufacturing the same.
[0002]
[Prior art]
In recent years, the development of lightweight, high energy density secondary batteries has been developed as a power source for electronic devices such as notebook personal computers, portable telephones, camera-integrated VTRs (video tape recorders), and PDAs (Personal Digital Assistants). Is underway. As a secondary battery having a high energy density, there is a lithium ion secondary battery having a higher energy density than an aqueous electrolyte battery such as a lead battery, a nickel cadmium battery, a nickel hydride battery, or the like.
[0003]
Since this lithium ion secondary battery has a higher voltage of 3 V or more than a water-based electrolyte battery or the like and can obtain a high electromotive force, it is necessary to output a large current in addition to the above-described electronic devices. For example, it is also used as a backup power supply for a relay base station of a portable telephone.
[0004]
Specifically, the lithium ion secondary battery 100 illustrated in FIG. 5 includes, as a power generation element, a battery element 104 in which, for example, a band-shaped positive electrode 101 and a band-shaped negative electrode 102 are wound with a band-shaped separator 103 interposed therebetween. The battery element 104 is sealed in a battery can 105 together with a non-aqueous electrolyte 106.
[0005]
In the lithium ion secondary battery 100, the positive electrode 101 has a positive electrode mixture layer 108 containing a positive electrode active material made of a lithium composite oxide or the like formed on a positive electrode current collector 107 made of a conductive metal such as aluminum, for example. A strip-shaped positive electrode terminal 109 electrically connected to the positive electrode current collector 107 is mounted substantially parallel to the short direction of the positive electrode 101. On the other hand, in the negative electrode 102, a negative electrode mixture layer 111 containing a negative electrode active material made of a carbonaceous material or the like is formed on a negative electrode current collector 110 made of a conductive metal such as copper, for example. The negative electrode terminal 112 in the form of a strip connected to the negative electrode 102 is attached substantially parallel to the short direction of the negative electrode 102.
[0006]
In the lithium ion secondary battery 100 having such a configuration, by optimizing the design capacity of the positive electrode active material and the negative electrode active material, for example, the generation of lithium dendrite, which occurs when lithium metal is used for the electrode, is eliminated. In addition, a decrease in voltage due to self-discharge is prevented, and excellent battery characteristics are obtained.
[0007]
[Problems to be solved by the invention]
However, in the above-described lithium ion secondary battery 100, a conductive metal or the like having a thickness of about 0.1 mm is used for the positive electrode terminal 109 and the negative electrode terminal 112, for example, in a position where the positive electrode terminal 109 and the negative electrode terminal 112 overlap. In the case of the battery element 104 arranged in the above, the roundness of the outer diameter of the battery element 104 is reduced.
[0008]
For this reason, in the lithium ion secondary battery 100, for example, it becomes difficult to insert the battery element 104 into the battery can 105, and the yield decreases during battery manufacturing. In this lithium ion secondary battery 100, the gap when the battery element 104 is inserted into the battery can 105 increases, and the energy density decreases. Therefore, in the lithium ion secondary battery 100, the positional relationship between the positive electrode terminal 109 and the negative electrode terminal 112 is very important for improving the yield and energy density during battery manufacturing.
[0009]
In addition, in this lithium ion secondary battery 100, when a large current flows, Joule heat generated near the center of the winding of the positive electrode 102 is stored inside the battery, the temperature rises, and the battery characteristics deteriorate. There is also. In particular, when the battery element 104 has a wound structure, when a large current flows, deterioration of the electrode becomes remarkable near the center of the winding due to Joule heat generated near the center of the winding of the positive electrode 102.
[0010]
Specifically, in the lithium ion secondary battery 100, when a large current flows, the current density near the winding center of the battery element 104 is large, so that the heat generated by Joule heat generated on the side of the positive electrode 102 near the winding center. Concentration occurs. Further, it is more difficult to radiate the generated heat to the outside in the vicinity of the winding center of the battery element 104 than in the vicinity of the outer periphery, so that further heat concentration occurs. Therefore, in the lithium ion secondary battery 100, when a large current flows, the electrodes are deteriorated due to heat concentration occurring near the center of the winding, and the battery characteristics are deteriorated.
[0011]
As a method for solving such a problem, for example, Japanese Patent Application Laid-Open No. 9-306545 discloses a method of providing a short-circuit component for the purpose of heat diffusion in a winding space of a battery element so that heat is stored near a winding axis. It has been proposed to diffuse the heat generated. Further, Japanese Patent Application Laid-Open No. 9-306545 proposes that when a battery is crushed, a short-circuit component is intentionally short-circuited so that large Joule heat is not generated.
[0012]
However, in such a method, in order to solve the above-mentioned problem, a short-circuit component is required, and the cost of the lithium ion secondary battery is increased. In addition, since an extra component such as a short-circuit component is used, the production yield when producing a lithium ion secondary battery also decreases.
[0013]
Therefore, the present invention has been proposed in view of such a conventional situation, and has non-aqueous electrolyte batteries in which electrodes are not deteriorated, battery characteristics are excellent, cost is reduced, and the yield is improved. It is intended to provide a way.
[0014]
[Means for Solving the Problems]
The non-aqueous electrolyte battery according to the present invention that achieves the above-described object has a positive electrode active material layer formed on a belt-shaped positive electrode current collector, and the positive electrode terminal of the positive electrode current collector is substantially in the lateral direction of the positive electrode current collector. The positive electrode connected in parallel and the negative electrode in which a negative electrode active material layer is formed on a strip-shaped negative electrode current collector, and the negative electrode terminal of the negative electrode current collector is connected substantially in parallel with the short direction of the negative electrode current collector. Having a battery element wound in the longitudinal direction via a separator, the positive electrode and the negative electrode have a positive electrode current collector in a range of 10 mm or more and 100 mm or less in the longitudinal direction at the ends on the inner peripheral side of the battery element, respectively. It has a positive electrode current collector exposed portion and a negative electrode current collector exposed portion where the negative electrode current collector is exposed, and a center angle between the positive electrode terminal and the negative electrode terminal with respect to a winding center of the battery element is approximately 120 °. Or, it is pulled out from the position where it is approximately 240 ° in the winding axis direction of the battery element It is characterized by.
[0015]
In this nonaqueous electrolyte battery, the positive electrode and the negative electrode have a positive electrode current collector exposed portion and a negative electrode current collector exposed portion in a predetermined range in the longitudinal direction at the inner peripheral end of the battery element. When a large current flows, Joule heat generated in the positive electrode current collector near the center of the winding propagates through the exposed portion of the negative electrode current collector on the inner peripheral side of the battery element and diffuses to the outside of the battery element.
[0016]
Thereby, in this nonaqueous electrolyte battery, when a large current flows, it is possible to suppress the storage of Joule heat near the center of the winding of the battery element.
[0017]
Further, in this nonaqueous electrolyte battery, the positive electrode terminal and the negative electrode terminal are pulled out in the winding axis direction of the battery element from a position where the center angle between each other with respect to the winding center of the battery element is approximately 120 ° or approximately 240 °. As a result, the roundness of the outer diameter of the battery element can be increased.
[0018]
A method for producing a nonaqueous electrolyte battery according to the present invention that achieves the above-described object includes a positive electrode in which a positive electrode mixture layer containing a positive electrode active material is formed on a band-shaped positive electrode current collector, and a band-shaped negative electrode current collector An electrode preparation step of preparing a negative electrode on which a negative electrode mixture layer containing a negative electrode active material is formed, and connecting a positive electrode terminal to the positive electrode current collector in a direction substantially parallel to the short direction of the positive electrode current collector; Attach to the positive electrode, connect the negative electrode terminal to the negative electrode current collector, and connect the negative electrode current collector substantially parallel to the short direction of the negative electrode current collector. An element manufacturing step of manufacturing a battery element by winding in the direction. In the electrode manufacturing step, the positive electrode current collector has a range of 10 mm or more and 100 mm or less in the longitudinal direction at the inner peripheral end of the battery element. And the positive electrode current collector exposed portion where the negative electrode current collector is exposed Produce a positive electrode and a negative electrode having a negative electrode current collector exposed portion, in the terminal mounting step, the center angle between the positive terminal and the negative terminal with respect to the winding center of the battery element is approximately 120 ° or approximately 240 °. It is characterized in that it is attached to the positive electrode and the negative electrode, respectively, so as to be drawn out from a certain position in the axial direction of the battery element.
[0019]
In the method of manufacturing a nonaqueous electrolyte battery, in the electrode manufacturing step, the positive electrode dielectric exposed portion in which the positive electrode current collector and the negative electrode current collector are exposed in a predetermined range in the longitudinal direction at the inner peripheral end of the battery element, respectively. And by producing a negative electrode and a negative electrode having a negative electrode current collector exposed portion, Joule heat generated in the positive electrode current collector near the center of the winding when a large current flows, the end of the battery element inner peripheral side Since the exposed portion of the negative electrode current collector propagates and diffuses outside the battery element, it is possible to manufacture a nonaqueous electrolyte battery in which Joule heat is not stored near the winding center of the battery element.
[0020]
In the method of manufacturing a nonaqueous electrolyte battery, in the terminal mounting step, the positive electrode terminal and the negative electrode terminal are positioned at a position where the center angle between the winding center of the battery element and each other is about 120 ° or about 240 °. By attaching the battery element to the positive electrode and the negative electrode so as to be drawn out in the axial direction of the element, a nonaqueous electrolyte battery in which the roundness of the outer diameter of the battery element is increased can be manufactured.
[0021]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a nonaqueous electrolyte battery to which the present invention is applied will be described with reference to a cylindrical lithium ion secondary battery (hereinafter, referred to as a battery) 1 shown in FIG. The battery 1 has a structure in which a battery element 2 serving as a power generation element is sealed inside a casing 3 together with a nonaqueous electrolyte 4.
[0022]
As shown in FIG. 2, the battery element 2 has a configuration in which a band-shaped positive electrode 5 and a band-shaped negative electrode 6 are wound in a longitudinal direction in a state of close contact with a band-shaped separator 7 interposed therebetween.
[0023]
The positive electrode 5 is coated on both main surfaces of the positive electrode current collector 8 with a positive electrode mixture coating solution containing a positive electrode active material and a binder, dried, and pressurized, so that the two main surfaces of the positive electrode current collector 8 are formed. The positive electrode mixture layer 9 is formed by compression. A positive electrode terminal 10 is connected to the positive electrode 4 at a predetermined position on the positive electrode current collector 8. For the positive electrode terminal 10, for example, a strip-shaped metal piece made of a conductive metal such as aluminum is used.
[0024]
In the positive electrode 5, a positive electrode current collector exposed portion 11 in which the positive electrode current collector 8 is exposed without forming the positive electrode mixture layer 9 on both main surfaces of the positive electrode current collector 8 is formed at both ends in the longitudinal direction. Is provided.
[0025]
When the positive electrode 5 is wound to form the battery element 2, the positive electrode current collector exposed portion 11 has such a length that the outermost side covers at least one circumference of the outer circumference of the battery element 2. I have. That is, in the positive electrode current collector exposed portions 11 provided at both ends in the longitudinal direction of the positive electrode 5, the length in the winding direction on the outer peripheral side of the battery element 2 is defined as L1, and the length outside the battery element 2 is defined. When the diameter is d, L1 ≧ dπ.
[0026]
On the other hand, in the positive electrode current collector exposed part 11, the positive electrode terminal 10 is attached to a predetermined position on the inner peripheral side of the battery element 2 so as to be along the winding axis direction of the battery element 2. The part of the positive electrode current collector exposed portion 11 that is on the inner peripheral side of the battery element 2 is wound a plurality of times at the center of the winding of the battery element 2.
[0027]
In the positive electrode 5, as the positive electrode active material contained in the positive electrode mixture layer 9, a material capable of doping / dedoping lithium ions is used. Specifically, for example, LiMxO2 (where M represents one or more transition metals of Co, Ni, Mn, Fe, Al, V, Ti, etc., and x is in a range of 0.5 or more and 1.10 or less. ) Is used. As the transition metal M constituting the lithium composite oxide, Co, Ni, Mn, or the like that can increase the battery capacity and obtain a stable crystal structure is preferable. Specific examples of such a lithium composite oxide include LiCoO2, LiNiO2, LiNiyCo1-yO2 (where 0 <y <1), LiMn2O4, and LiNixMnyCozO2 (where 0≤x≤1, 0≤y). ≦ 1, 0 ≦ z ≦ 1) and the like.
[0028]
As the positive electrode active material, for example, LixFe1-yMyPO4 (where M is Mn, Cr, Co, Cu, Ni, V, Mo, Ti, Zn, Al, Ga, Mg, A compound represented by the formula: 0.05 ≦ x ≦ 1.2, and 0 ≦ y <0.8). Specific examples thereof include LiFePO4 and the like. Used. Further, as the positive electrode active material, for example, metal sulfides or oxides such as TiS2, MoS2, NbSe2, and V2O5 can be used.
[0029]
In the positive electrode 5, as a binder for the positive electrode mixture layer 9, for example, a binder such as polyvinylidene fluoride or polytetrafluoroethylene used for the positive electrode mixture of a nonaqueous electrolyte battery can be used. For example, a carbonaceous material or the like as a conductive material or a known additive or the like can be added to the agent layer 9. In the positive electrode 5, for the positive electrode current collector 8, a foil-like metal or a net-like metal made of a conductive metal such as aluminum is used.
[0030]
The negative electrode 6 is coated on both main surfaces of the negative electrode current collector 12 with a negative electrode mixture coating solution containing a negative electrode active material and a binder, dried, and pressurized, so that the negative electrode current collector 12 is coated on both main surfaces. The negative electrode mixture layer 13 is formed by compression. A negative electrode terminal 14 is connected to the negative electrode 6 at a predetermined position on the negative electrode current collector 12. For the negative electrode terminal 14, for example, a strip-shaped metal piece made of a conductive metal such as copper or nickel is used.
[0031]
In the negative electrode 6, the negative electrode current collector 12 is exposed without forming the negative electrode mixture layer 13 on both main surfaces of the negative electrode current collector 12 in order from the edge at one end of both ends in the longitudinal direction. The negative electrode current collector exposed portion 15 and the negative electrode single-sided mixture portion 16 in which the negative electrode mixture layer 13 is formed only on one main surface of the negative electrode current collector 12 are provided. In the negative electrode 6, only the negative electrode current collector exposed portion 15 is provided at the other end of both ends in the longitudinal direction.
[0032]
Of the two ends in the longitudinal direction of the negative electrode 6, the negative electrode current collector exposed portion 15 at one end is disposed on the outer peripheral side when the negative electrode 6 is wound and becomes the battery element 2, and The length is set so as to cover at least one circumference of the outer circumference. That is, when the length in the winding direction of the negative electrode current collector exposed portion 15 provided on one end side of the negative electrode 6 is L2 and the outer diameter of the battery element 2 is d, L2 ≧ dπ. A negative electrode terminal 14 is attached to a predetermined position of the negative electrode current collector exposed portion 15 on one end side so as to be along the winding axis direction of the battery element 2.
[0033]
The negative electrode single-sided mixture portion 16 on one end side of the longitudinal end portions of the negative electrode 6 is provided on one main surface of the negative electrode current collector 12 on the side facing the positive electrode mixture layer 9. Is formed, and the other main surface of the negative electrode current collector 12 on the side not facing the positive electrode mixture layer 9 is exposed. Further, the negative electrode single-sided mixture portion 16 has a length that covers at least one circumference of the outer periphery of the battery element 2 so that the positive electrode mixture layer 9 and the negative electrode mixture layer 13 appropriately face each other.
[0034]
On the other hand, of the two ends in the longitudinal direction of the negative electrode 6, the negative electrode current collector exposed portion 15 on the other end side is at the winding center of the battery element 2 with the above-described positive electrode current collector exposed portion 11 and the separator 7 interposed therebetween. In this state, the coils are opposed and wound a plurality of times.
[0035]
In the negative electrode 6, as the negative electrode active material contained in the negative electrode mixture layer 13, lithium, a lithium alloy, or a carbonaceous material capable of doping / dedoping lithium ions is used. Examples of the carbonaceous material that can be doped / dedoped with lithium ions include a low-crystalline carbon material obtained by firing at a relatively low temperature of 2000 ° C. or less, and artificial graphite obtained by firing a raw material that easily crystallizes at a high temperature of about 3000 ° C. It is possible to use a highly crystalline carbon material or the like. Specifically, it is possible to use carbonaceous materials such as pyrolytic carbons, cokes, graphites, glassy carbon fibers, fired organic polymer compounds, carbon fibers, and activated carbon. Examples of cokes include pitch coke, needle coke, petroleum coke, and the like. The fired organic polymer compound is obtained by firing a phenol resin, a furan resin, or the like at an appropriate temperature and carbonizing the resin. These carbonaceous materials can suppress the deposition of lithium on the negative electrode 6 side when the battery 1 is charged and discharged. In addition to the above-mentioned carbonaceous materials, polymers such as polyacetylene and polypyrrole and oxides such as SnO2 can be used as materials capable of doping / dedoping lithium ions. As the lithium alloy, for example, a lithium-aluminum alloy or the like is used.
[0036]
In the negative electrode 6, as the binder of the negative electrode mixture layer 13, for example, a binder such as polyvinylidene fluoride or polytetrafluoroethylene used for the negative electrode mixture of the nonaqueous electrolyte battery can be used. In the negative electrode 6, for the negative electrode current collector 12, a foil-like metal or a net-like metal made of a conductive metal such as copper is used.
[0037]
The separator 7 separates the positive electrode 5 and the negative electrode 6 from each other, and may use a known material that is generally used as an insulating porous film of this type of nonaqueous electrolyte battery. Specifically, for example, a polymer film such as polypropylene or polyethylene is used. Further, from the relationship between lithium ion conductivity and energy density, it is preferable that the thickness of the separator 7 is as thin as possible, and the separator 7 is used with the thickness being 30 μm or less.
[0038]
In the battery element 2 having the above-described configuration, the positive electrode current collector exposed portion 11 and the negative electrode current collector exposed portion 15 are arranged in the longitudinal direction near the inner ends of the positive electrode 5 and the negative electrode 6, that is, near the center of the winding. At a predetermined length with a separator 7 interposed therebetween.
[0039]
Thereby, in the battery element 2, when a large current flows through the battery 1, Joule heat generated in the positive electrode 5 near the center of the winding is transferred from the exposed positive electrode current collector 11 near the center of the winding to the negative electrode. The Joule heat propagated to the current collector exposed portion 15 and propagated to the negative electrode 6 side acts to diffuse outside.
[0040]
Therefore, in the battery element 2, when a large current flows through the battery 1, Joule heat can be suppressed from being stored near the center of the winding, and the positive electrode 5 and the negative electrode 6 are prevented from being deteriorated by heat, and the battery 1 can suppress a decrease in battery characteristics.
[0041]
In the battery element 2, the length of the positive electrode current collector exposed portion 11 and the length of the negative electrode current collector exposed portion 15 are 10 mm or more and 100 mm or less in the longitudinal direction at the ends of the positive electrode 5 and the negative electrode 6 on the inner peripheral side. It is in the range.
[0042]
When the longitudinal lengths of the positive electrode current collector exposed portion 11 and the negative electrode current collector exposed portion 15 near the winding center of the battery element 2 are each shorter than 10 mm, this occurs when a large current flows through the battery 1. It becomes difficult to diffuse Joule heat to the outside. On the other hand, when the longitudinal lengths of the positive electrode current collector exposed portion 11 and the negative electrode current collector exposed portion 15 near the winding center of the battery element 2 are each longer than 100 mm, the current collectors of the positive electrode 5 and the negative electrode 6 Since there are too many exposed parts and the active material is reduced, the battery capacity is reduced.
[0043]
Therefore, in the battery element 2, the lengths of the positive electrode current collector exposed portion 11 and the negative electrode current collector exposed portion 15 at the inner peripheral side end portions of the positive electrode 5 and the negative electrode 6 are respectively set to 10 mm or more and 100 mm or less in the longitudinal direction. With this range, Joule heat generated when a large current flows through the battery 1 can be appropriately diffused, and a decrease in battery capacity can be suppressed.
[0044]
Further, in the battery element 2, even when the positive electrode current collector exposed portion 11 and the negative electrode current collector exposed portion 15 facing each other near the center of the winding fall into an abnormal state such as the battery 1 being crushed, for example, The heat generated by short-circuit between the negative electrode 5 and the negative electrode 6 acts so as to be appropriately diffused.
[0045]
Further, in the battery element 2, since the negative electrode single-sided mixture portion 16 is provided, the amount of the negative electrode mixture layer 13 not facing the positive electrode mixture layer 9 inside the battery is reduced, and the amount of the positive electrode mixture layer 13 facing each other is reduced accordingly. The layer 9 and the negative electrode mixture layer 13 can be increased, and the energy density of the battery 1 is improved.
[0046]
Furthermore, in this battery element 2, as shown in FIGS. 3A and 3B, the center angle between the positive electrode terminal 10 and the negative electrode terminal 14 with respect to the center of winding is approximately 120 ° or approximately. It is pulled out from the position of 240 ° in the winding axis direction.
[0047]
Thereby, in the battery element 2, the roundness of the outer diameter can be increased, and the battery element 2 can be smoothly inserted into the outer can 3 or the like. In the battery element 2, the positive electrode terminal 11 and the negative electrode terminal 14 are pulled out from a position where the center angle between them with respect to the winding center is in the range of 115 ° to 125 ° or in the range of 235 ° to 245 °. However, the roundness of the outer diameter can be increased.
[0048]
The outer can 3 is, for example, a cylindrical container with a bottom, and has a bottom surface having a circular shape or the like. The outer can 3 has a circular bottom in FIG. 1, but the present invention is not limited to this. For example, a bottomed cylindrical container having a rectangular or flat circular bottom can be applied. . When the outer can 3 is electrically connected to the negative electrode 6, the outer can 3 is formed of a conductive metal such as iron, stainless steel, and nickel. When the outer can 3 is made of, for example, iron or the like, its surface is plated with nickel or the like.
[0049]
The non-aqueous electrolyte 4 is, for example, a non-aqueous solution in which an electrolyte salt is dissolved in a non-aqueous solvent. In the non-aqueous electrolyte 4, as the non-aqueous solvent, for example, a cyclic carbonate compound, a cyclic carbonate compound in which hydrogen is substituted with a halogen group or a halogenated acryl group, a chain carbonate compound, or the like is used. Specifically, propylene carbonate, ethylene carbonate, diethyl carbonate, dimethyl carbonate, 1,2-dimethoxyethane, 1,2-diethoxyethane, γ-butyrolactone, tetrahydrofuran, 2-methyltetrahydrofuran, 1,3-dioxolan, Examples thereof include methyl 1,3 dioxolan, diethyl ether, sulfolane, methyl sulfolane, acetonitrile, propionitrile, anisole, acetate, butyrate, and propionate, and one or more of these are used. In particular, propylene carbonate, dimethyl carbonate, and diethyl carbonate are preferably used as the non-aqueous solvent from the viewpoint of voltage stability.
[0050]
Examples of the electrolyte salt include LiPF6, LiClO4, LiAsF6, LiBF4, LiB (C6H5) 4, LiCH3SO3, LiCF3SO3, LiCl, and LiBr. One or more of these are used.
[0051]
The battery 1 configured as described above is manufactured as follows. First, the positive electrode 5 is manufactured. When producing the positive electrode 5, a positive electrode mixture coating liquid containing a positive electrode active material, a conductive material, and a binder is prepared. Then, the positive electrode mixture coating liquid is uniformly applied to both main surfaces of the positive electrode current collector 8 while providing uncoated portions, dried, and then compressed to form the positive electrode mixture layer 9 to form a belt-like shape. The positive electrode terminal 10 is cut and attached to a predetermined position by, for example, ultrasonic welding. In this way, the positive electrode 5 having the positive electrode current collector exposed portion 11 in which the positive electrode current collector 8 is exposed at both ends in the longitudinal direction is manufactured.
[0052]
Next, the negative electrode 6 is manufactured. When producing the negative electrode 6, a negative electrode mixture coating liquid containing a negative electrode active material and a binder is prepared. Then, the negative electrode mixture coating liquid is uniformly applied to both main surfaces of the negative electrode current collector 12 while providing an uncoated portion or a single-sided coated portion, dried, and then compressed to form the negative electrode mixture layer 13. The negative electrode terminal 14 is formed, cut into a band shape, and the negative electrode terminal 14 is attached to a predetermined position by, for example, ultrasonic welding. In this manner, at one end in the longitudinal direction, the negative electrode current collector exposed portion 15 where the negative electrode current collector 12 is exposed, and the negative electrode single-sided mixture portion 16 where the negative electrode current collector 12 is exposed on only one side. Is provided, and the negative electrode 6 in which only the negative electrode current collector exposed portion 15 is provided at the other end in the longitudinal direction is manufactured.
[0053]
Next, the positive electrode 5 and the negative electrode 6 are laminated with a band-shaped separator 7 interposed therebetween, and are wound many times to produce the battery element 2.
[0054]
At this time, in the battery element 2, the positive electrode current collector exposed portion 11 and the negative electrode current collector exposed portion 15 have a length within a predetermined range in the winding direction of the battery element 2 at the inner peripheral end of the battery element 2. And are wound so as to face each other.
[0055]
In the battery element 2, the positive electrode terminal 10 is attached to the inner peripheral side positive electrode current collector exposed portion 11, and the negative electrode terminal 14 is attached to the outer peripheral side negative electrode current collector exposed portion 15. In the battery element 2, the positive electrode terminal 10 and the negative electrode terminal 14 are wound so as to be pulled out in a winding axis direction from a position where a center angle between the winding center and each other is approximately 120 ° or approximately 240 °. I have.
[0056]
Next, as shown in FIG. 1, insulating plates 17 a and 17 b are provided on both end surfaces of the battery element 2, and the battery element 2 is housed in the outer can 3. Then, in order to collect the current of the negative electrode 6, the portion of the negative electrode terminal 14 protruding from the battery element 2 is welded to the bottom of the outer can 3 or the like. Thus, the outer can 3 is electrically connected to the negative electrode 6 and serves as an external negative electrode of the battery 1. Further, in order to collect the current of the positive electrode 5, a portion of the positive electrode terminal 10 protruding from the battery element 2 is welded to the current interrupting thin plate 18 to electrically connect with the battery lid 19 via the current interrupting thin plate 18. Connect to The current interrupting thin plate 18 interrupts the current according to the internal pressure of the battery. As a result, the battery lid 19 is electrically connected to the positive electrode 5 and serves as an external positive electrode of the battery 1.
[0057]
Next, the nonaqueous electrolyte 4 is injected into the outer can 3 in which the battery element 2 is stored. The non-aqueous electrolyte 4 is prepared by dissolving an electrolyte salt in a non-aqueous solvent. Next, the battery lid 19 is fixed by caulking the opening of the outer can 3 via a gasket 20 coated with a sealing agent made of asphalt or the like, and the battery 1 is manufactured.
[0058]
In this battery 1, when the pressure inside the battery becomes higher than a predetermined value, a safety valve 21 for bleeding out the gas inside the battery 1 and a positive temperature coefficient (PTC) element 22 for preventing a rise in temperature inside the battery. Etc. are provided.
[0059]
In the battery 1 manufactured as described above, the positive electrode current collector exposed portion 11 and the negative electrode current collector exposed portion 15 are opposed to each other at a predetermined length in the longitudinal direction of the electrode near the center of the winding of the battery element 2. Since the Joule heat generated in the positive electrode 5 near the center of the winding when a large current flows is propagated from the exposed part of the positive electrode current collector 11 facing the center of the wound to the exposed part of the negative electrode current collector 15, Joule heat propagated to the negative electrode 6 can be easily diffused to the outside.
[0060]
Therefore, in the battery 1, when a large current flows, the storage of Joule heat near the center of the winding can be suppressed, and the deterioration of the positive electrode 5 and the negative electrode 6 due to the Joule heat is prevented. Reduction can be suppressed.
[0061]
Also, in this battery 1, a large current is exposed by causing the positive electrode current collector exposed portion 11 and the negative electrode current collector exposed portion 15 to face each other at a predetermined length in the longitudinal direction of the electrode near the winding center of the battery element 2. Since the Joule heat generated when the gas flows can be appropriately diffused to the outside, it is possible to reduce the cost by reducing the conventionally used short-circuiting parts for the purpose of thermal diffusion.
[0062]
Further, in the battery 1, even when an abnormal situation such as crushing occurs, the heat generated by short-circuiting the positive electrode 5 and the negative electrode 6 is transferred to the positive electrode current collector exposed portion 11 and the negative electrode current collector exposed portion. 15 can be appropriately diffused by being opposed in the vicinity of the center of the winding of the battery element 2, so that the temperature can be suppressed from being high and safety can be improved.
[0063]
Furthermore, in the battery 1, since the negative electrode 6 is provided with the negative electrode single-sided mixture portion 16, the amount of the negative electrode mixture layer 13 that does not face the positive electrode mixture layer 9 inside the battery is reduced, and the battery mixture layers 13 face each other accordingly. Since the positive electrode mixture layer 9 and the negative electrode mixture layer 13 can be increased, the battery capacity and the energy density can be improved.
[0064]
Furthermore, in the battery 1, the positive electrode terminal 10 and the negative electrode terminal 14 are arranged such that the center angle between the positive electrode terminal 10 and the negative electrode terminal 14 with respect to the winding center of the battery element 2 is approximately 120 ° or approximately 240 ° in the winding axis direction of the battery element 2 And the roundness of the outer diameter of the battery element 2 can be increased. Thereby, in the battery 1, when the battery is manufactured, the battery element 2 can be smoothly inserted into the outer can 3, and the trouble that occurs when the battery element 2 is inserted into the outer can 3 is suppressed. Therefore, the yield during battery production can be improved.
[0065]
In the above example, the battery 1 using the non-aqueous electrolyte 4 has been described. However, the present invention is not limited to this. For example, an inorganic solid electrolyte, a polymer solid electrolyte, It is also applicable when a gel electrolyte or the like is used. Examples of the inorganic solid electrolyte include lithium nitride and lithium iodide.
[0066]
The polymer solid electrolyte is composed of, for example, the above-described electrolyte salt and a polymer compound which is imparted with ionic conductivity by containing the electrolyte salt. As the polymer compound used for the polymer solid electrolyte, for example, silicon, polyether-modified siloxane, polyacryl, polyacrylonitrile, polyphosphazene, polyethylene oxide, polypropylene oxide, and their composite polymers, crosslinked polymers, modified polymers, such as acrylonitrile Ether polymers such as butadiene rubber, polyacrylonitrile-butadiene styrene rubber, acrylonitrile-polyethylene chloride-propylene-diene-styrene resin, acrylonitrile-vinyl chloride resin, acrylonitrile-methacrylate resin, acrylonitrile-acrylate resin, and crosslinked products of polyethylene oxide And any one of them or a mixture of a plurality of them.
[0067]
Further, as the polymer compound used for the polymer solid electrolyte, for example, acrylonitrile, vinyl acetate, methyl methacrylate, butyl methacrylate, methyl acrylate, butyl acrylate, itaconic acid, methyl acrylate hydroxide, ethyl acrylate hydroxide, Copolymers obtained by copolymerizing any one or more of acrylamide, vinyl chloride, vinylidene fluoride, etc., poly (vinylidene fluoride), poly (vinylidene fluoride-co-hexafluoropropylene), poly (vinylidene fluoride) Also, a fluorine-based polymer such as ride-co-tetrafluoroethylene) and poly (vinylidenefluorolide-co-trifluoroethylene) may be mentioned, and any one or a mixture of these may be used.
[0068]
The gel electrolyte is composed of the above-described non-aqueous electrolyte 4 and a matrix polymer that absorbs the non-aqueous electrolyte 4 and gels. As the matrix polymer used for the gel electrolyte, for example, among the above-described polymer compounds, any of the above-described polymer compounds that absorb the non-aqueous electrolyte 4 and gelate can be used. Specifically, examples of the matrix polymer include fluorine-based polymers such as poly (vinylidene fluoride) and poly (vinylidene fluoride-co-hexafluoropropylene), and ethers such as poly (ethylene oxide) and cross-linked products thereof. And high-molecular-weight polymers, poly (acrylonitrile) and the like, and any one or a mixture of these may be used. In particular, it is preferable to use a fluoropolymer having good oxidation-reduction stability as the matrix polymer.
[0069]
In the above-described embodiment, the cylindrical battery 1 has been described as an example. However, the present invention is not limited to this, and if a battery element having a wound structure is provided, for example, The present invention can be applied to nonaqueous electrolyte batteries of various sizes and shapes, such as a battery using a metal container or the like as an exterior material, a battery using a laminate film or the like as an exterior material, or a thin type.
[0070]
【Example】
Hereinafter, a sample in which a lithium ion secondary battery is actually manufactured as a nonaqueous electrolyte battery to which the present invention is applied will be described.
[0071]
<Sample 1>
In sample 1, first, a positive electrode was manufactured. When producing a positive electrode, 91 parts by weight of LiMn2O4 as a positive electrode active material, 6 parts by weight of graphite as a conductive material, 3 parts by weight of polyvinylidene fluoride (PVdF) as a binder, and N-methyl-2 as a solvent -Pyrrolidone (NMP) was added, and the mixture was kneaded and dispersed by a planetary mixer to prepare a positive electrode mixture coating liquid. Next, the positive electrode mixture coating liquid is uniformly applied while providing uncoated portions on both main surfaces of a 20 μm-thick aluminum foil serving as a positive electrode current collector, dried, and then compressed by a roller press. A positive electrode mixture layer was formed and cut into a band. In this manner, a positive electrode having a positive electrode current collector exposed portion where the positive electrode current collector was exposed at both ends in the longitudinal direction was produced. Specifically, a positive electrode having a thickness of 160 μm, a width of 55 mm, a length of the positive electrode mixture layer of 500 mm, and a length of the exposed portion of the positive electrode current collector of 70 mm was produced.
[0072]
Next, a positive electrode terminal was attached to a predetermined position of the exposed portion of the positive electrode current collector so as to be substantially parallel to the short direction of the positive electrode.
[0073]
Next, a negative electrode was manufactured. When preparing the negative electrode, 90 parts by weight of a carbonaceous material as a negative electrode active material, 10 parts by weight of PVdF as a binder, and NMP as a solvent were added and kneaded with a planetary mixer to perform dispersion. A mixture coating liquid was prepared. Next, the negative electrode mixture coating liquid was uniformly applied to both main surfaces of a 15 μm thick copper foil serving as a negative electrode current collector while providing an uncoated portion or a single-sided coated portion, followed by drying. A negative electrode mixture layer was formed by compressing with a machine, and cut into a band shape. In this manner, at one end in the longitudinal direction, a negative electrode current collector exposed portion where the negative electrode current collector is exposed, and a negative electrode single-sided mixture portion where the negative electrode current collector is exposed on only one side are provided, A negative electrode provided with only the negative electrode current collector exposed portion at the other end in the longitudinal direction was manufactured. Specifically, the thickness is 160 μm, the width is 57 mm, the length of the negative electrode mixture layer is 500 mm, the length of the exposed portion of the negative electrode current collector at one end is 80 mm, the length of the one-sided negative electrode mixture portion is 50 mm, and the current is collected at the other end. A negative electrode having a body exposed portion with a length of 40 mm was prepared.
[0074]
Next, a negative electrode terminal was attached to the negative electrode current collector exposed portion on one end side in the longitudinal direction of the negative electrode so as to be substantially parallel to the short direction of the negative electrode.
[0075]
Next, the positive electrode and the negative electrode were laminated via a belt-shaped separator made of a porous film made of polypropylene, and were wound many times in the longitudinal direction of the electrode to produce a battery element.
[0076]
At this time, in the battery element, the negative electrode is wound so that one end side of the negative electrode is on the inner peripheral side, and the exposed portions of the positive electrode current collector and the negative electrode current collector are separated from each other by the inner peripheral end of the positive electrode and the negative electrode. To face each other. Further, in the battery element, the positive electrode terminal was arranged on the inner peripheral side exposed portion of the positive electrode current collector, and the negative electrode terminal was arranged on the outer peripheral side exposed portion of the negative electrode current collector. Further, in the battery element, the positive electrode terminal and the negative electrode terminal were wound so as to be pulled out in the winding axis direction from a position where the center angle between each other with respect to the winding center was 120 °.
[0077]
Next, the positive electrode terminal derived from the battery element prepared as described above was welded to a battery lid, the negative electrode terminal was welded to an outer can that was nickel-plated with iron, and the battery element was housed in the outer can. .
[0078]
Next, a non-aqueous electrolyte was prepared in which LiPF6 was dissolved in a mixed solvent of propylene carbonate and diethyl carbonate at a volume mixing ratio of 1: 1 so that LiPF6 was 1 mol / L. Next, the non-aqueous electrolyte was poured into the outer can, and the battery lid was pressed into the opening of the outer can via a gasket coated with asphalt, and the opening of the outer can was swaged to close the battery lid. Firmly fixed.
[0079]
As described above, a cylindrical lithium ion secondary pond having a diameter of 18 mm and a height of 65 mm was produced. In the following description, a lithium ion secondary battery is simply referred to as a battery for convenience.
[0080]
<Sample 2>
In Sample 2, when the battery element was manufactured, the positive electrode terminal and the negative electrode terminal were wound so as to be pulled out in the winding axis direction from a position where the center angle between each other with respect to the winding center was 240 °. Then, a battery was fabricated in the same manner as in Sample 1, except that this battery element was used.
[0081]
<Sample 3>
In sample 3, a positive electrode was prepared in the same manner as in sample 1, except that the length of the exposed portion of the positive electrode current collector at one end was 40 mm when the positive electrode was prepared. Further, a negative electrode was prepared in the same manner as in Sump 1 except that the length of the exposed portion of the negative electrode current collector at one end was 5 mm when the negative electrode was prepared. Next, a battery element was manufactured using the positive electrode and the negative electrode manufactured as described above. At this time, the end of the positive electrode provided with the exposed portion of the positive electrode current collector having a length of 40 mm and the end of the negative electrode provided with the exposed portion of the negative electrode current collector having a length of 5 mm are on the inner peripheral side. The battery element was wound. Then, a battery was fabricated in the same manner as in Sample 1, except that the battery element fabricated in this manner was used.
[0082]
<Sample 4>
In Sample 4, when the battery element was manufactured, the positive electrode terminal and the negative electrode terminal were wound so as to be drawn out in the winding axis direction from a position where the center angle between each other with respect to the winding center was 0 °. Then, a battery was fabricated in the same manner as in Sample 1, except that this battery element was used.
[0083]
<Sample 5>
In the case of Sample 5, the battery element was wound so that the positive electrode terminal and the negative electrode terminal were pulled out in the winding axis direction from a position where the central angle between each other with respect to the winding center was 30 °. Then, a battery was fabricated in the same manner as in Sample 1, except that this battery element was used.
[0084]
<Sample 6>
In the case of Sample 6, when the battery element was manufactured, the positive electrode terminal and the negative electrode terminal were wound so as to be drawn out in the winding axis direction from a position where the central angle between each other with respect to the winding center was 60 °. Then, a battery was fabricated in the same manner as in Sample 1, except that this battery element was used.
[0085]
<Sample 7>
In the case of Sample 7, when producing the battery element, the positive electrode terminal and the negative electrode terminal were wound so as to be pulled out in the direction of the winding axis from a position where the central angle between each other with respect to the winding center was 90 °. Then, a battery was fabricated in the same manner as in Sample 1, except that this battery element was used.
[0086]
<Sample 8>
In the case of Sample 8, the battery element was wound so that the positive electrode terminal and the negative electrode terminal were pulled out in the direction of the winding axis from a position where the center angle between each other with respect to the winding center was 150 °. Then, a battery was fabricated in the same manner as in Sample 1, except that this battery element was used.
[0087]
<Sample 9>
In the case of Sample 9, the battery element was wound so that the positive electrode terminal and the negative electrode terminal were pulled out in the direction of the winding axis from a position where the center angle between each other with respect to the winding center was 180 °. Then, a battery was fabricated in the same manner as in Sample 1, except that this battery element was used.
[0088]
<Sample 10>
In Sample 10, when the battery element was manufactured, the positive electrode terminal and the negative electrode terminal were wound so as to be pulled out in the winding axis direction from a position where the center angle between each other with respect to the winding center was 210 °. Then, a battery was fabricated in the same manner as in Sample 1, except that this battery element was used.
[0089]
<Sample 11>
In Sample 11, when the battery element was manufactured, the positive electrode terminal and the negative electrode terminal were wound so as to be drawn in the winding axis direction from a position where the center angle between each other with respect to the winding center was 270 °. Then, a battery was fabricated in the same manner as in Sample 1, except that this battery element was used.
[0090]
<Sample 12>
In the case of Sample 12, when the battery element was manufactured, the positive electrode terminal and the negative electrode terminal were wound so as to be drawn out in the winding axis direction from a position where the center angle between each other with respect to the winding center was 300 °. Then, a battery was fabricated in the same manner as in Sample 1, except that this battery element was used.
[0091]
<Sample 13>
In the case of Sample 13, when the battery element was manufactured, the positive electrode terminal and the negative electrode terminal were wound so as to be drawn out in the winding axis direction from a position at which the central angle with respect to the winding center was 330 °. Then, a battery was fabricated in the same manner as in Sample 1, except that this battery element was used.
[0092]
Then, among the samples 1 to 13 prepared as described above, the charge and discharge cycle characteristics of the batteries of sample 1 and sample 3 when charging and discharging were performed at a large current were measured.
[0093]
Table 1 below shows the evaluation results of the discharge capacity maintenance ratio at the 200th cycle due to heavy load charging and discharging in Samples 1 and 3.
[0094]
[Table 1]

[0095]
In samples 1 and 3, charging and discharging were performed as follows. At the time of charging, the battery was charged at a constant current and a constant voltage with a charging current value of 3 A and an upper limit voltage of 4.2 V for 3 hours. On the other hand, when discharging, a constant current discharge up to 3 V at a current value of 6 A was performed. The charge / discharge was repeated 200 times under such charge / discharge conditions, and the discharge capacity maintenance ratio at the 200th cycle, that is, the ratio of the 200th discharge capacity to the initial discharge capacity was measured.
[0096]
From the evaluation results shown in Table 1, in the sample 1 in which the positive electrode current collector exposed portion having a length of 70 mm and the negative electrode current collector exposed portion having a length of 40 mm were opposed on the inner peripheral side of the battery element, On the inner peripheral side of the element, compared to Sample 3 in which the exposed portion of the positive electrode current collector having a length of 40 mm and the exposed portion of the negative electrode current collector having a length of 5 mm were opposed to each other, the 200th cycle due to heavy load charging and discharging was performed. It can be seen that the discharge capacity retention ratio has increased.
[0097]
In Sample 3, particularly, the length of the negative electrode current collector exposed portion on the inner peripheral side of the battery element is as short as 5 mm, and Joule heat generated on the positive electrode side when a large current flows is appropriately applied to the negative electrode current collector exposed portion. It cannot be propagated, making it difficult to diffuse the heat inside the battery to the outside. For this reason, in Sample 3, since large Joule heat is generated near the center of the winding of the battery element having a large current density and is stored, the electrode is deteriorated due to heat concentration particularly near the center of the winding of the battery element. The characteristics also deteriorate.
[0098]
On the other hand, in Sample 1, the exposed portion of the positive electrode current collector and the exposed portion of the negative electrode current collector on the inner peripheral side of the battery element have an appropriate length, and in particular, the exposed portion of the negative electrode current collector is 40 mm. Joule heat generated on the positive electrode side when a large current flows is appropriately transmitted to the exposed portion of the negative electrode current collector, and the heat inside the battery can be easily diffused to the outside. Therefore, in the sample 1, since the Joule heat generated by the large current is suppressed from being stored in the battery and the deterioration of the electrode due to the heat is also suppressed, the battery characteristics superior to the sample 3 can be obtained.
[0099]
Here, in Sample 1 and Sample 3, the temperature changes at the center of the battery element and the outer peripheral surface of the battery when the battery was discharged under the above-described discharge conditions were measured. FIG. 4 shows the measurement results of the temperature change in Sample 1 and Sample 3 when discharging with a large current. FIG. 4 is a characteristic diagram showing the relationship between the discharge time and the temperature change in Sample 1 and Sample 3.
[0100]
From the evaluation results shown in FIG. 4, in Sample 1, the temperature is low at the center of the battery element and is high at the outer peripheral surface of the battery. On the other hand, in sample 3, the temperature is high at the center of the battery element and is low at the outer peripheral surface of the battery.
[0101]
Therefore, the sample 1 has a structure in which the Joule heat is stored in the battery and the heat is easily diffused to the outside. The sample 3 stores the Joule heat in the battery and diffuses the heat to the outside. It can be seen that the structure is difficult.
[0102]
From the above, when manufacturing a battery, it is possible to make the exposed portion of the positive electrode current collector having a length of 70 mm and the exposed portion of the negative electrode current collector having a length of 40 mm face each other near the winding center of the battery element. It can be seen that this is very effective in producing a battery having an excellent discharge capacity retention ratio at the 200th cycle due to heavy load charging and discharging.
[0103]
Next, for the batteries of Sample 1, Sample 2, and Samples 4 to 13, the maximum diameter of the battery element was measured, and the element insertion failure rate when the battery element was housed in the outer can was investigated.
[0104]
Table 2 below shows the maximum diameter of the battery element and the battery element insertion failure rate in Samples 1 and 2, and Samples 4 to 13.
[0105]
[Table 2]

[0106]
From the evaluation results shown in Table 2, Sample 1 in which the positive electrode terminal and the negative electrode terminal were drawn in the winding axis direction from the position where the central angle between each other with respect to the winding center was 120 ° or 240 ° in the battery element. In Sample 2, the positive electrode terminal and the negative electrode terminal are drawn in the direction of the winding axis from a position where the center angle of each other with respect to the center of the winding is other than 120 ° or 240 °. ~ It can be seen that the maximum diameter of the battery element is smaller and the battery element insertion failure rate is lower than that of Sample 13.
[0107]
In Samples 4 to 13, the positive electrode terminal and the negative electrode terminal were drawn out of positions where the center angle between them with respect to the winding center of the battery element was other than 120 ° or 240 °, and the outer diameter of the battery element was true. The roundness is reduced and the maximum diameter of the battery element is increased. For this reason, in Samples 4 to 13, it becomes difficult to insert the battery element into the outer can, and the battery element hits the periphery of the opening of the outer can and the like, and the separator and the like are often broken.
[0108]
On the other hand, in Sample 1 and Sample 2, the positive electrode terminal and the negative electrode terminal are pulled out from the position where the center angle between them with respect to the winding center of the battery element is 120 ° or 240 °, and the outer diameter of the battery element is The roundness increases and the maximum diameter of the battery element decreases. For this reason, in the sample 1 and the sample 2, since the battery element can be smoothly inserted into the outer can, the occurrence of the battery element insertion failure is suppressed as compared with the samples 4 to 13, and the production yield can be improved.
[0109]
From the above, when manufacturing a battery, it is possible to pull out the positive electrode terminal and the negative electrode terminal in the winding axis direction from a position where the central angle between each other with respect to the winding center of the battery element is 120 ° or 240 °. In addition, it can be seen that the maximum diameter of the battery element is reduced and the defective insertion rate when the battery element is inserted into the outer can is reduced, which is very effective in improving the yield at the time of manufacturing the battery.
[0110]
【The invention's effect】
As is clear from the above description, according to the present invention, the positive electrode current collector exposed portion and the negative electrode current collector exposed portion in a predetermined range are provided at the positive electrode end and the negative electrode end on the inner peripheral side of the wound battery element. By providing the portion, the deterioration of the electrode caused by Joule heat generated by the large current is concentrated on the vicinity of the winding center of the battery element is suppressed, so that the non-aqueous electrolyte battery in which the deterioration of the battery characteristics is suppressed is provided. can get.
[0111]
Further, according to the present invention, the positive electrode terminal and the negative electrode terminal are pulled out in the winding axis direction of the battery element from a position where the center angle between each other with respect to the winding center of the battery element is approximately 120 ° or approximately 240 °. As a result, the roundness of the outer diameter of the battery element is increased, and the battery element can be smoothly inserted into the outer can, so that the yield during battery fabrication can be improved.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view showing an internal structure of a lithium ion secondary battery to which the present invention is applied.
FIG. 2 is a schematic diagram showing an internal structure of the lithium ion secondary battery from a cross section.
FIG. 3 is a schematic side view of a battery element showing the mounting positions of a positive electrode terminal and a negative electrode terminal in the lithium ion secondary battery as viewed from the winding axis direction, and FIG. On the other hand, FIG. 11B shows a state in which the center angle formed by the positive terminal and the negative terminal is 120 ° with respect to the center of the winding of the battery element. This shows a certain state.
FIG. 4 is a characteristic diagram showing a relationship between a discharge time and a battery temperature in Samples 1 and 3.
FIG. 5 is a schematic view showing an internal structure of a conventional lithium ion secondary battery from a cross section.
[Explanation of symbols]
REFERENCE SIGNS LIST 1 lithium ion secondary battery, 2 battery element, 3 outer can, 4 nonaqueous electrolyte, 5 positive electrode, 6 negative electrode, 7 separator, 8 positive electrode current collector, 9 positive electrode mixture layer, 10 positive electrode terminal, 11 positive electrode current collector Body exposed portion, 12 negative electrode current collector, 13 negative electrode mixture layer, 14 negative electrode terminal, 15 negative electrode current collector exposed portion, 16 negative electrode single-sided mixture portion

Claims (4)

A positive electrode in which a positive electrode active material layer is formed on a band-shaped positive electrode current collector, a positive electrode terminal of which is connected to the positive electrode current collector substantially in parallel with a lateral direction of the positive electrode current collector, and a band-shaped negative electrode current collector A negative electrode active material layer was formed thereon, and a negative electrode in which the negative electrode terminal was connected to the negative electrode current collector in a direction substantially parallel to the short direction of the negative electrode current collector was wound in the longitudinal direction via a separator. Having a battery element,
The positive electrode and the negative electrode are exposed at the ends on the inner peripheral side of the battery element, where the positive electrode current collector and the negative electrode current collector are exposed in a range of 10 mm or more and 100 mm or less in the longitudinal direction, respectively. And a negative electrode current collector exposed portion,
The positive electrode terminal and the negative electrode terminal are drawn out in a winding axis direction of the battery element from a position at which a center angle with respect to a winding center of the battery element is about 120 ° or about 240 °. Characteristic non-aqueous electrolyte battery. The nonaqueous electrolyte battery according to claim 1, wherein the positive electrode active material and the negative electrode active material can be doped / dedoped with lithium ions. A positive electrode in which a positive electrode mixture layer containing a positive electrode active material is formed on a belt-shaped positive electrode current collector, and a negative electrode in which a negative electrode mixture layer containing a negative electrode active material is formed on a band-shaped negative electrode current collector An electrode manufacturing process to be manufactured;
A positive electrode terminal is attached to the positive electrode by connecting the positive electrode terminal to the positive electrode current collector substantially in parallel with a short direction of the positive electrode current collector, and a negative electrode terminal is connected to the negative electrode current collector by a short side of the negative electrode current collector. A terminal mounting step of connecting to the negative electrode by connecting substantially parallel to the direction,
The positive electrode, the negative electrode, an element manufacturing step of manufacturing a battery element by winding in the longitudinal direction via a separator,
In the electrode preparation step, the positive electrode current collector and the negative electrode current collector are exposed in a range of 10 mm or more and 100 mm or less in the longitudinal direction at the end on the inner peripheral side of the battery element. Producing the positive electrode and the negative electrode having a negative electrode current collector exposed portion,
In the terminal mounting step, the positive electrode terminal and the negative electrode terminal are pulled out from the position where the center angle between the winding center of the battery element and each other is about 120 ° or about 240 ° in the axial direction of the battery element. A method for manufacturing a non-aqueous electrolyte battery, wherein the method is attached to each of the positive electrode and the negative electrode. 4. The method for producing a nonaqueous electrolyte battery according to claim 3, wherein in the electrode forming step, a positive electrode active material capable of doping / dedoping lithium ions and the negative electrode active material are used.

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