JP4081833B2 - Sealed non-aqueous electrolyte secondary battery - Google Patents

Description

【０１２０】
〔表１〕から明らかなように、Ｖ₁ ／Ｖ₂ が２％よりも小さい電池（水準ａ）は液漏れ試験で２個の不良（液漏れ）が発生した。また、Ｖ₁ ／Ｖ₂ が３０％よりも大きい電池（水準ｂ）はブレーカー作動試験で３個の不良（ブレーカー作動）が発生した。Ｖ₁ ／Ｖ₂ が２〜３０％の電池（水準Ａ、Ｂ、Ｃ、Ｄ）では不良の発生はなく、保存特性を満足した。
【０１２１】
（実施例−２）
負極材料としてＳｎ_0.8 Ｓｉ_0.5 Ｂ_0.3 Ｐ_0.2 Ａｌ_0.1 Ｏ_2.9 を使用し、また電池サイズとして１８６５０サイズ（外径１８ｍｍ、高さ６５ｍｍ）とした以外は（実施例−１）と全く同様にして電池を作成し、同様に保存特性を評価した。
【０１２２】
結果を〔表２〕に示した。表中の分母は良品数を示し、分子は不良品数を示す。
【０１２３】
【表２】

【０１２４】
〔表２〕においても、〔表１〕と同様に、Ｖ₁ ／Ｖ₂ が２％よりも小さい電池（水準ｃ）は液漏れ試験で１個の不良（液漏れ）が発生した。また、Ｖ₁ ／Ｖ₂ が３０％よりも大きい電池（水準ｄ）はブレーカー作動試験で２個の不良（ブレーカー作動）が発生した。Ｖ₁ ／Ｖ₂ が２〜３０％の電池（水準Ｅ、Ｆ、Ｇ、Ｈ）では不良の発生はなく、保存特性を満足した。Ｖ₁ ／Ｖ₂ は２〜３０％が好ましい。
【０１２５】
【発明の効果】
電解液を注入した封口した後の電池内部の空間体積を電解液を注入しない時の空間体積の２％以上、３０％以下にすることにとより、保存特性に優れ、良好なサイクル性を有する密閉型非水電解液二次電池を得ることができる。
【図面の簡単な説明】
【図１】円筒型電池の断面図である。
【符号の説明】
１ 電池缶
２ 負極
３ 正極
４ セパレータ
５ 下部絶縁板
６ 上部絶縁板
７ ガスケット
８ 正極リード
９ 防爆弁体
１０ 電流遮断スイッチ
１０ａ 第一導通体
１０ｂ 第二導通体
１０ｃ 絶縁リング
１１ ＰＴＣリング
１３ 端子キャップ
１５ 溶接プレート
１６ 絶縁カバー[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a high-capacity sealed nonaqueous electrolyte secondary battery with improved storage stability and cycle characteristics.
[0002]
[Prior art]
In recent years, with the widespread use of portable electronic devices such as notebook personal computers and mobile phones, the use of high-capacity lithium ion secondary batteries has increased rapidly compared to conventional NiCd batteries and NiMH batteries. Yes.
[0003]
Since lithium ion secondary batteries store high energy, safety measures when an abnormality occurs are emphasized. In conventional secondary batteries, a safety valve that releases pressure when the internal pressure of the battery rises due to an abnormality has been used. A method is described in which the lead is peeled off from the explosion-proof valve and cuts off the current when a predetermined internal pressure is reached. Most lithium-ion secondary batteries that have been put to practical use have a structure in which an explosion-proof valve body for pressure release and a current interrupting device are linked.
[0004]
However, there is a problem that the current interrupting device operates or the electrolyte leaks under a high temperature environment or the like, and a more stable operation of the safety device is required.
[0005]
[Problems to be solved by the invention]
An object of the present invention is to provide a high-capacity sealed nonaqueous electrolyte secondary battery having excellent storage stability and good cycleability.
[0006]
[Means for Solving the Problems]
  According to one aspect of the present invention, a positive electrode sheet having a layer mainly composed of a lithium-containing metal oxide, a negative electrode sheet having a layer mainly composed of a negative electrode material capable of occluding and releasing lithium, and a non-containing lithium salt In a non-aqueous electrolyte secondary battery comprising a water electrolyte and a separator, the sealed non-aqueous electrolyte secondary battery is inserted into a battery can by laminating or winding the positive electrode sheet, the negative electrode sheet and the separator, The ratio of the space volume (V1) inside the battery after injecting the water electrolyte and sealing the battery can to the space volume (V2) when not injecting the electrolyte (percentage of (V1 / V2)) is 2%. -30%, the amount of water in the electrolyte is 0.1-500 ppm, and further has a pressure-sensitive current interrupting device in the battery can, the current interrupting device comprising an explosion-proof valve and a current Includes shutoff switch, battery internal pressure is 1 ~15kgf / cm ² The explosion-proof valve body of the explosion-proof valve is deformed when the valve is raised, and the current cutoff switch cuts off the current.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, although the preferable aspect of this invention is demonstrated, this invention is not limited to these.
[0008]
(1) A positive electrode sheet having a layer mainly composed of a lithium-containing metal oxide, a negative electrode sheet having a layer mainly composed of a negative electrode material capable of occluding and releasing lithium, a non-aqueous electrolyte containing a lithium salt, and a separator. In the non-aqueous electrolyte secondary battery, the positive electrode sheet, the negative electrode sheet and the separator are stacked or wound and inserted into the battery can, the non-aqueous electrolyte is injected, and the space volume inside the battery after sealing the battery can is A sealed nonaqueous electrolyte secondary battery characterized by being 2% or more and 30% or less of the space volume when the nonaqueous electrolyte is not injected.
[0009]
(2) The sealed nonaqueous electrolyte secondary battery according to item 1, further comprising a pressure-sensitive current interrupting device in the battery can.
[0010]
(3) The negative electrode sheet has at least one layer mainly composed of a negative electrode material capable of occluding and releasing lithium, and the negative electrode sheet has a weight fluctuation when exposed to 220 ° C. for 2 hours before battery assembly. Item 3. The sealed nonaqueous electrolyte secondary battery according to Item 1 or 2, which is 0.6% or less.
[0011]
(4) The negative electrode sheet has a layer mainly composed of a negative electrode material capable of inserting and extracting lithium at least one layer, and an auxiliary layer containing at least one layer of conductive particles, and lithium is mainly formed on the auxiliary layer. Item 4. The sealed non-aqueous electrolyte secondary battery according to any one of Items 1 to 3, wherein the metal foil is overlapped.
[0012]
(5) The sealed nonaqueous electrolyte secondary battery according to any one of (1) to (4), wherein the negative electrode material is a composite oxide or composite chalcogenide containing tin.
[0013]
(6) The sealed nonaqueous electrolyte secondary battery according to item 5, wherein the composite oxide containing tin is a compound represented by the following general formula (1).
SnM_aO_z            General formula (1)
In the formula, M represents two or more elements selected from Al, B, P, Si, Ge, Periodic Table Group 1 element, Group 2 element, Group 3 element, and halogen element. Numbers of 2 or more and 2 or less are shown in Table 1, and z is a number of 1 or more and 6 or less.
[0014]
The form of the Example of this invention is explained in full detail below.
FIG. 1 is a cross-sectional view of a cylinder type battery. The battery shape can be applied to both cylinders and corners. A cylindrical battery can be manufactured by making the winding core into a cylinder shape, and a rectangular battery can be manufactured by making the winding core into a square shape. The battery is formed by inserting the positive electrode sheet 3 and the negative electrode sheet 2 wound together with the separator 4 into the battery can 1, electrically connecting the battery can 1 and the negative electrode sheet 2, and injecting and sealing the electrolyte. The terminal cap 13 also serves as a positive electrode terminal and is fitted into the upper opening of the battery can 1 via the gasket 7. The positive electrode sheet 3 is electrically connected to the terminal cap 13 via a positive electrode lead 8, a welding plate 15, an explosion-proof valve body 9, a current cutoff switch 10, and a positive temperature coefficient resistance (hereinafter referred to as PTC) ring 11.
[0015]
In the sealing body, the terminal cap 13, the PTC ring 11, the current cutoff switch 10, and the explosion-proof valve body 9 are stacked in order from the top, and are fitted and supported by the gasket 7. The terminal cap 13 is a surface exposed portion of the battery, and the explosion-proof valve body 9 is inside the battery. The insulating cover 16 covers the upper surface of the explosion-proof valve body 9. The current cutoff switch 10 includes a first conductive body 10a, a second conductive body 10b, and an insulating ring 10c.
[0016]
The electrode group is obtained by winding the positive electrode sheet 3 and the negative electrode sheet 2 with the separator 4 interposed therebetween. The upper insulating plate 6 is disposed between the electrode group and the explosion-proof valve body 9. The upper insulating plate 6 insulates the electrode group and the sealing body, and insulates the electrode group and the battery can 1. A lower insulating plate 5 is disposed between the electrode group and the battery can 1 to insulate the electrode group from the battery can 1.
[0017]
The PTC ring 11 has a function of cutting off current by increasing resistance when the temperature inside the battery rises. The current cutoff switch 10 is a laminated structure of a first conducting body 10a, an insulating ring 10c, and a second conducting body 10b. The first conducting body 10a is disposed on the explosion-proof valve body 9 side and has a through hole. The conductive body 10b is arranged on the PTC ring 11 side, that is, the terminal cap 13 side, and has a structure having a through hole. The first conductor 10a and the second conductor 10b are electrically connected at the center, and have a thin portion around the connection portion of the first conductor 10a. The explosion-proof valve body 9 can be deformed to the side opposite to the electrode group side when the internal pressure is increased, and may be anything that can push up the central connection portion of the first conductive body 10a. When the internal pressure rises due to an abnormal reaction in the battery, the explosion-proof valve body 9 is deformed to break the connecting portion between the first conducting body 10a and the second conducting body 10b of the current cutoff switch 10 to cut off the current. If it increases, the thin part of the explosion-proof valve body 9 is destroyed and the pressure is released. At this time, since the current cut-off switch 10 is arranged on the side opposite to the electrode group side of the explosion-proof valve body 9, even if a spark occurs in the cut-off portion, the battery is prevented from rupture due to ignition of the electrolyte vapor. Is done.
[0018]
The positive and negative electrodes used in the non-aqueous secondary battery can be prepared by coating and molding a positive electrode mixture or a negative electrode mixture on a current collector. In addition to the positive electrode active material or the negative electrode material, the positive electrode or the negative electrode mixture can contain a conductive agent, a binder, a dispersant, a filler, an ionic conductive agent, a pressure enhancer, and various additives, respectively.
[0019]
It is known that the ratio of voids in the electrode (positive electrode 3 or negative electrode 2) greatly affects battery performance. In particular, in a battery using a nonaqueous solvent as an electrolyte, such as a lithium nonaqueous electrolyte secondary battery, it is important to control the porosity in order to obtain an appropriate discharge capacity and cycle characteristics.
[0020]
To control the porosity, there is a method to adjust the size and mixing ratio of the active material, conductive material, binder, etc. in the electrode mixture, but changing the mixing ratio will change the amount of electrode active material. It is not preferable. Therefore, a method of changing the porosity by mechanical compression is used.
[0021]
The porosity of the electrode is preferably set to 10% to 40%. As a method for controlling the porosity, a method of applying pressure after applying the electrode mixture to the current collector, particularly compression by a roll press is preferable.
[0022]
The porosity after compression is preferably 10% or more and 40% or less, and particularly preferably 15% or more and 30% or less. If it is 10% or less, the penetration of the non-aqueous electrolyte into the electrode is slow, and if it is 40% or more, the volumetric energy density at the time of battery discharge is reduced. The value of the porosity here is an average value for the entire surface of the mixture layer on the electrode.
Space volume when the electrolyte of the sealed battery is not injected (hereinafter referred to as V₂ Is the volume of the space when the electrolyte is not injected into the space formed by the battery can 1 and the sealing portion for sealing. In the cylindrical sealed battery shown in FIG. 1, the wound electrode group and the insulating plates 5, 6, etc. from the battery internal volume constituted by the explosion-proof valve body of No. 9, the gasket of No. 7 and the battery can of No. 1 This is the volume of the space excluding the volume of the constituent members. V₂ After inserting the wound electrode group and the constituent members into the battery can 1, a liquid paraffin (at room temperature) is obtained by caulking and sealing with a sealing body including the battery can 1 and the explosion-proof valve body 9 without injecting the electrolyte solution. It can be determined by immersing in JIS standard K9003 (special grade product), removing the adhering bubbles and then decomposing and collecting the air and measuring its volume. As the liquid paraffin, for example, liquid paraffin made by Wako Pure Chemical can be used as a commercial product. V₂ Includes a space between the electrodes 2 and 3 and the separator 4 of the wound electrode group, and a space caused by pores (voids) of the porous electrode and the separator. In order to replace air with liquid paraffin in the gap between the separator 4 and the electrode, it is preferable to measure the volume after performing a swinging process or an ultrasonic vibration process.
[0023]
Space volume inside battery after electrolyte injection (hereinafter referred to as V₁ Is a space that can be formed inside the battery after injecting and sealing the electrolyte and producing the battery, and V₂ It can be measured by the same method.
[0024]
V₁ And V₂ Ratio (V₁ / V₂ 2 to 30% is preferable, 3 to 27% is more preferable, and 4 to 24% is particularly preferable. When it is less than 2%, the pressure in the battery increases excessively with respect to slight fluctuations such as an increase in environmental temperature during storage, and the sealing portion may be destroyed. When it is larger than 30%, when an abnormal reaction occurs in the battery, the current interrupting device (including the explosion-proof valve body 9 and the current interrupting switch 10) may not operate.
[0025]
Battery internal pressure is 10-15kgf / cm²When the valve is raised, the explosion-proof valve body 9 is deformed and the current cutoff switch 10 cuts off the current. Furthermore, the battery internal pressure is about 30 kgf / cm.²When it rises, the explosion-proof valve body 9 is destroyed and the internal pressure of the battery is released. In order to operate this current interrupting device at the above pressure, V₁ / V₂ Must be set to the above value.
[0026]
Any of the pressure-sensitive current interrupting devices can be applied as long as the current is interrupted according to the battery internal pressure. Since the interruption device described in Japanese Patent Laid-Open No. 2-112151 described above is located at a position where the current is cut off in contact with the electrolytic solution or the vapor of the electrolytic solution, the structure described in Japanese Patent Laid-Open No. 9-92334 is preferred. Is preferred. The interruption device described in Japanese Patent Laid-Open No. 9-92334 includes a dish-shaped explosion-proof valve body having a protrusion that deforms in accordance with the battery internal pressure, and a current interruption device (current interruption switch) that is pushed up by the valve body protrusion and breaks. It is configured.
[0027]
It is believed that the moisture inside the battery causes the electrolyte to decompose. Therefore, the excessive presence of moisture is the preferred space volume ratio (V₁ / V₂ ), The decomposition gas of the electrolytic solution is generated, and the internal pressure of the battery is gradually increased, causing the leakage and the early operation of the current interrupting device.
[0028]
The negative electrode sheet desirably contains as little moisture as possible. For this reason, the negative electrode sheet is subjected to heat treatment at 200 to 250 ° C. for 5 minutes to 2 hours after coating, drying and press molding. The negative electrode sheet dehydrated by the heat treatment is handled in dry air having a dew point of −50 ° C. or less, slit into the battery assembly width (distance in the vertical direction in FIG. 1), and stored until battery assembly. It is preferable that the battery is further dehydrated at 170 to 230 ° C. for 10 minutes to 3 hours before battery assembly. At this time, the air sent to the dehydration treatment zone is preferably dry air having a dew point of minus 50 ° C. or less. The weight loss when the electrode is heated before battery assembly is such that the weight variation when exposed to 220 ° C. for 2 hours at normal pressure in the dry air before battery assembly is 0.6% or less. Preferably, 0.5% or less is more preferable, and 0.4% or less is particularly preferable. When the weight loss is greater than 0.6%, the sealing portion is destroyed due to fluctuations in the environmental temperature or the like during storage, and failure such as leakage of the electrolyte is likely to occur.
[0029]
The negative electrode sheet is obtained by applying a negative electrode mixture composed of a negative electrode material, a binder, a conductive agent, and the like on a current collector.
[0030]
The negative electrode material may be any compound that can occlude and release lithium ions. Examples of such negative electrode materials include metallic lithium, lithium alloys, carbonaceous compounds, inorganic oxides, inorganic chalcogen compounds, metal complexes, and organic polymer compounds. These may be used alone or in combination.
[0031]
As the negative electrode material, an amorphous chalcogen compound or an amorphous oxide mainly containing three or more kinds of atoms selected from Group 1, 2, 13, 14, and 15 group atoms of the periodic table is particularly preferably used. The term “amorphous” as used herein refers to an X-ray diffraction method using CuKα rays, which has a broad scattering band having an apex from 20 ° to 40 ° as a 2θ value, and has a crystalline diffraction line. Also good.
[0032]
Preferably, the strongest intensity of the crystalline diffraction lines seen at 2θ values of 40 ° or more and 70 ° or less is 500 of diffraction line intensities at the apexes of broad scattering bands seen at 20 ° or more and 40 ° or less of 2θ values. It is preferably not more than twice, more preferably not more than 100 times, particularly preferably not more than 5 times, and most preferably not having a crystalline diffraction line.
[0033]
The above chalcogen compound and oxide are composite chalcogen compounds mainly composed of two or more elements of B, Al, Ga, In, Tl, Si, Ge, Sn, Pb, P, As, Sb, and Bi, A composite oxide is more preferable. Particularly preferred are complex chalcogen compounds or oxides mainly composed of two or more elements of B, Al, Si, Ge, Sn, and P. These composite chalcogen compounds and composite oxides mainly contain at least one element selected from elements of Groups 1 to 2 of the periodic table in order to modify the amorphous structure.
[0034]
Among the above negative electrode materials, an amorphous composite oxide mainly composed of Sn is preferable, and is represented by the following general formula (1).
[0035]
SnM_aO_z          General formula (1)
In the formula, M represents two or more elements selected from Al, B, P, Si, Ge, Periodic Table Group 1 element, Group 2 element, Group 3 element, and halogen element. A number of 2 or more and 2 or less, z represents a number of 1 or more and 6 or less.
[0036]
The amorphous composite oxide can employ either a firing method or a solution method, but a firing method is more preferable. In the firing method, it is preferable to obtain an amorphous composite oxide by thoroughly mixing oxides or compounds of the elements described in the general formula (1) and then firing.
[0037]
As firing conditions, the rate of temperature rise is preferably 5 ° C. or more and 200 ° C. or less per minute, the firing temperature is preferably 500 ° C. or more and 1500 ° C. or less, and the firing time is 1 hour or more and 100 hours. The following is preferable. In addition, the cooling rate is 2 ° C. or more per minute and 10⁷ It is preferable that it is below ℃.
[0038]
The rate of temperature rise is the average rate of temperature rise from “50% of the firing temperature (indicated in ° C.)” to “80% of temperature in the fired (expressed in ° C.)”. This is the average rate of temperature drop from reaching “80% of temperature (indicated in degrees Celsius)” to “50% of firing temperature (indicated in degrees Celsius)”.
[0039]
The temperature drop may be cooled in a firing furnace or taken out of the firing furnace and may be cooled, for example, in water. In addition, a super rapid cooling method such as a gun method, a Hammer-Anvil method, a slap method, a gas atomization method, a plasma spray method, a centrifugal quenching method, or a melt drag method described on page 217 of ceramics processing (Gihodo Publishing 1987) can also be used. Moreover, you may cool using the single roller method and the double roller method of New Glass Handbook (Maruzen 1991) p.172. In the case of a material that melts during firing, the fired product may be continuously taken out while supplying raw materials during firing. In the case of a material that melts during firing, it is preferable to stir the melt.
[0040]
The firing gas atmosphere is preferably an atmosphere having an oxygen content of 5% by volume or less, and more preferably an inert gas atmosphere. Examples of the inert gas include nitrogen, argon, helium, krypton, and xenon. The most preferred inert gas is pure argon.
[0041]
The average particle size of the above compound is preferably 0.1 to 60 μm. More specifically, it is preferable that the average particle size is 0.7 to 25 μm and the particle size of 60% or more of the total volume is 0.5 to 30 μm. The volume occupied by the particle group having a particle diameter of 1 μm or less of the negative electrode active material is preferably 30% or less of the total volume, and the volume occupied by the particle group having a particle diameter of 20 μm or more is preferably 25% or less of the total volume. Needless to say, the particle size of the material used does not exceed the thickness of the mixture on one side of the negative electrode.
[0042]
To obtain a predetermined particle size, a well-known pulverizer or classifier is used. For example, a mortar, a ball mill, a sand mill, a vibrating ball mill, a satellite ball mill, a planetary ball mill, a swirling air flow type jet mill, a sieve, or the like is used. When pulverizing, wet pulverization in the presence of water or an organic solvent such as methanol can be performed as necessary. In order to obtain a desired particle size, classification is preferably performed. The classification method is not particularly limited, and a sieve, an air classifier, or the like can be used as necessary. Classification can be used both dry and wet.
[0043]
The average particle diameter is a median diameter of primary particles, and is measured by a laser diffraction type particle size distribution measuring apparatus.
[0044]
The specific surface area of the negative electrode material is 0.1 to 5 m as measured by the BET specific surface area measurement method.²/ G is preferable.
[0045]
Examples of the negative electrode material are shown below, but are not limited thereto.
SnAl_0.4B_0.5P_0.5K_0.1O_3.65, SnAl_0.4B_0.5P_0.5Na_0.2O_3.7,
SnAl_0.4B_0.3P_0.5Rb_0.2O_3.4, SnAl_0.4B_0.5P_0.5Cs_0.1O_3.65,
SnAl_0.4B_0.5P_0.5K_0.1Ge_0.05O_3.85, SnAl_0.4B_0.5P_0.5K_0.1Mg_0.1Ge_0.02O_3.83, SnAl_0.4B_0.4P_0.4O_3.2, SnAl_0.3B_0.5P_0.2O_2.7,
SnAl_0.3B_0.5P_0.2O_2.7, SnAl_0.4B_0.5P_0.3Ba_0.08Mg_0.08O_3.26, SnAl_0.4B_0.4P_0.4Ba_0.08O_3.28, SnAl_0.4B_0.5P_0.5O_3.6, SnAl_0.4B_0.5P_0.5Mg_0.1O_3.7
[0046]
SnAl_0.5B_0.4P_0.5Mg_0.1F_0.2O_3.65, SnB_0.5P_0.5Li_0.1Mg_0.1F_0.2O_3.05, SnB_0.5P_0.5K_0.1Mg_0.1F_0.2O_3.05, SnB_{0. Five}P_0.5K_0.05Mg_0.05F_0.1O_3.03, SnB_0.5P_0.5K_0.05Mg_0.1F_0.2O_3.03, SnAl_0.4B_0.5P_0.5Cs_0.1Mg_0.1F_0.2O_3.65, SnB_0.5P_0.5Cs_0.05Mg_0.05F_0.1O_3.03, SnB_0.5P_0.5Mg_0.1F_0.1O_3.05, SnB_0.5P_0.5Mg_0.1F_0.2O_Three , SnB_0.5P_0.5Mg_0.1F_0.06O_3.07, SnB_0.5P_0.5Mg_0.1F_0.14O_3.03, SnPBa_0.08O_3.58, SnPK_0.1O_3.55, SnPK_0.05Mg_0.05O_3.58, SnPCs_0.1O_3.55, SnPBa_0.08F_0.08O_3.54, SnPK_0.1Mg_0.1F_0.2O_3.55, SnPK_0.05Mg_0.05F_0.1O_3.53, SnPCs_0.1Mg_0.1F_0.2O_3.55, SnPCs_0.05Mg_0.05F_0.1O_3.53,
[0047]
Sn_1.1Al_0.4B_0.2P_0.6Ba_0.08F_0.08O_3.54, Sn_1.1Al_0.4B_0.2P_0.6Li_0.1K_0.1Ba_0.1F_0.1O_3.65, Sn_1.1Al_0.4B_0.4P_0.4Ba_0.08O_3.34,
Sn_1.1Al_0.4PCs_0.05O_4.23, Sn_1.1Al_0.4PK_0.05O_4.23, Sn_1.2Al_0.5B_0.3P_0.4Cs_0.2O_3.5, Sn_1.2Al_0.4B_0.2P_0.6Ba_0.08O_3.68, Sn_1.2Al_0.4B_0.2P_0.6Ba_0.08F_0.08O_3.64, Sn_1.2Al_0.4B_0.2P_0.6Mg_0.04Ba_0.04O_3.68, Sn_1.2Al_0.4B_0.3P_0.5Ba_0.08O_3.58, Sn_1.3Al_0.3B_0.3P_0.4Na_0.2O_3.3 , Sn_1.3Al_0.2B_0.4P_0.4Ca_0.2O_3.4, Sn_1.3Al_0.4B_0.4P_0.4Ba_0.2O_3.6, Sn_1.4Al_0.4PK_0.2O_4.6, Sn_1.4Al_0.2Ba_0.1PK_0.2O_4.45, Sn_1.4Al_0.2Ba_0.2PK_0.2O_4.6, Sn_1.4Al_0.4Ba_0.2PK_0.2Ba_0.1F_0.2O_4.9, Sn_1.4Al_0.4PK_0.3O_4.65, Sn_1.5Al_0.2PK_0.2O_4.4, Sn_1.5Al_0.4PK_0.1O_4.65, Sn_1.5Al_0.4PCs_0.05O_4.63, Sn_1.5Al_0.4PCs_0.05Mg_0.1F_0.2O_4.63
[0048]
SnSi_0.5Al_0.1B_0.2P_0.1Ca_0.4O_3.1, SnSi_0.4Al_0.2B_0.4O_2.7,
SnSi_0.5Al_0.2B_0.1P_0.1Mg_0.1O_2.8, SnSi_0.6Al_0.2B_0.2O_2.8,
SnSi_0.5Al_0.3B_0.4P_0.2O_3.55, SnSi_0.5Al_0.3B_0.4P_0.5O_4.30,
SnSi_0.6Al_0.1B_0.1P_0.3O_3.25, SnSi_0.6Al_0.1B_0.1P_0.1Ba_0.2O_2.95.
SnSi_0.6Al_0.1B_0.1P_0.1Ca_0.2O_2.95, SnSi_0.6 Al_0.4B_0.2Mg_0.1O_3.2, SnSi_0.6Al_0.1B_0.3P_0.1O_3.05, SnSi_0.6Al_0.2Mg_0.2O_2.7, SnSi_0.6Al_0.2Ca_0.2O_2.7, SnSi_0.6Al_0.2P_0.2O_Three , SnSi_0.6B_0.2P_0.2O_Three , SnSi_0.8Al_0.2O_2.9, SnSi_0.8Al_0.3B_0.2P_0.2O_3.85, SnSi_0.8B_0.2O_2.9, SnSi_0.8Ba_0.2O_2.8, SnSi_0.8Mg_0.2O_2.8, SnSi_0.8Ca_0.2O_2.8, SnSi_0.8P_0.2O_3.1
[0049]
Sn_0.9Mn_0.3B_0.4P_0.4Ca_0.1Rb_0.1O_2.95, Sn_0.9Fe_0.3B_0.4P_0.4Ca_0.1Rb_0.1O_2.95, Sn_0.8Pb_0.2Ca_0.1P_0.9O_3.35, Sn_0.3Ge_0.7Ba_0.1P_0.9 O_3.35, Sn_0.9Mn_0.1Mg_0.1P_0.9O_3.35, Sn_0.2Mn_0.8Mg_0.1P_0.9O_3.35, Sn_0.7Pb_0.3Ca_0.1P_0.9O_3.35, Sn_0.2Ge_0.8Ba_0.1P_0.9O_3.35.
[0050]
SnSi_0.8B_0.2O_2.9, SnSi_0.7B_0.3O_2.85, SnSi_0.7B_0.3Al_0.1O_3.0, SnSi_0.5B_0.3Al_0.1Mg_0.1O_2.7, Sn_0.8Si_0.6B_0.2Al_0.1Li_0.1O_2.5, Sn_0.8Si_0.6B_0.2Al_0.1Cs_0.1O_2.65, Sn_0.8Si_0.7B_0.1P_0.1Al_0.1O_2.75, Sn_0.8Si_0.5B_0.3P_0.2Al_0.1O_2.9, Sn_0.8Si_0.7B_0.1P_0.1Al_0.1Li_0.05O_2.78, Sn_0.8Si_0.5B_0.3P_0.1Al_0.1Li_0.1O_2.7, Sn_0.8Si_0.5B_0.3P_0.2Al_0.1Cs_0.1O_2.95, Sn_0.8Si_0.7P_0.3O_2.95, Sn_0.8Si_0.7P_0.3Al_0.1O_3.1, SnSi_0.5B_0.3Zr_0.1O_2.65,
Sn_0.8Si_0.6P_0.2Zr_0.1O_2.7, Sn_0.8Si_0.6B_0.2P_0.1Zr_0.1O_2.75
[0051]
The chemical formula of the compound obtained by firing can be calculated from an inductively coupled plasma (ICP) emission spectroscopic analysis method as a measurement method and a weight difference between powders before and after firing as a simple method.
[0052]
As the negative electrode material, a light metal, in particular, lithium can be inserted and used. Examples of the lithium insertion method include an electrochemical method, a chemical method, and a thermal method. Particularly preferred is an electrochemical method. For example, a small piece of lithium-based metal is pasted on an uncoated part of the negative electrode mixture of the current collector or a negative electrode mixture layer, and inserted by contacting with an electrolytic solution. it can. In particular, a method of electrochemically inserting lithium in the battery is preferable, and a method of attaching lithium via an auxiliary layer described later and contacting the electrolyte solution. It is preferable that the metal piece mainly composed of lithium is pasted in the form of a strip having a thickness of 5 to 200 μm.
[0053]
Lithium can be inserted up to 0.01V, more preferably up to 0.05V when lithium is used as a counter electrode. A particularly preferable method is a method of partially inserting lithium in order to compensate for the irreversible capacity of the negative electrode material, and a method of inserting up to 0.3 V when lithium is used as a counter electrode.
[0054]
More specifically, the amount of lithium inserted is 0.005 g to 0.5 g, more preferably 0.03 g to 0.2 g, and particularly preferably 0.06 g to 0.15 g per 1 g of the negative electrode material. When the negative electrode material is a metal oxide, the equivalent per mole of metal oxide is 0.5 to 4.0 equivalent, more preferably 1 to 3.5 equivalent, and particularly preferably 1.2 to 3 .2 equivalents. When lithium less than 1.2 equivalents is preliminarily inserted into the negative electrode material, the battery capacity is low, and when more than 3.2 equivalents of lithium is preliminarily inserted, cycle performance is deteriorated.
[0055]
The amount of lithium inserted can be arbitrarily controlled by the amount of lithium superimposed on the negative electrode sheet. As the metal mainly composed of lithium, lithium metal is preferably used, but a metal having a purity of 90% by weight or more is preferable, and a metal having a purity of 98% by weight or more is particularly preferable. As the overlapping pattern of lithium on the negative electrode sheet, it is preferable to overlap the entire surface of the sheet, but since lithium preliminarily inserted into the negative electrode material gradually diffuses into the negative electrode material due to aging, it is not a full sheet, but a stripe, frame shape Also, any partial overlap of disk-like is preferable. The term “lamination” as used herein means that a metal foil mainly composed of lithium is directly bonded onto a sheet having a negative electrode mixture and an auxiliary layer.
[0056]
The coverage of the metal foil overlapping in the negative electrode sheet is preferably 10 to 100%, more preferably 15 to 100%, and particularly preferably 20 to 100%. When it is 20% or less, the preliminary insertion of lithium may become uneven, which is not preferable. Further, from the viewpoint of uniformity, the thickness of the metal foil mainly composed of lithium is preferably 5 to 150 μm, more preferably 5 to 100 μm, and particularly preferably 10 to 75 μm.
[0057]
The handling atmosphere such as cutting and sticking of the metal foil mainly composed of lithium is preferably a dry air or argon gas atmosphere having a dew point of −30 ° C. or lower and −80 ° C. or higher. In the case of dry air, −40 ° C. or lower and −80 ° C. or higher is more preferable. Carbon dioxide gas may be used in combination during handling. Particularly in the case of an argon gas atmosphere, it is preferable to use carbon dioxide in combination.
[0058]
Next, the positive electrode will be described. The positive electrode active material is preferably a lithium-containing transition metal oxide. The lithium-containing transition metal oxide is an oxide mainly containing at least one transition metal element selected from Ti, V, Cr, Mn, Fe, Co, Ni, Mo, and W and lithium, This is a compound having a transition metal molar ratio of 0.3 to 2.2.
[0059]
More preferably, the oxide mainly contains at least one transition metal element selected from V, Cr, Mn, Fe, Co, and Ni and lithium, and the molar ratio of lithium to transition metal is 0.3 to 0.3. It is the compound of 2.2. In addition, Al, Ga, In, Ge, Sn, Pb, Sb, Bi, Si, P, B, or the like may be contained within a range of less than 30 mole percent with respect to the transition metal present mainly.
[0060]
More preferred lithium-containing transition metal oxides are Li_xCoO₂ , Li_xNiO₂ , Li_xMnO₂ , Li_xCo_aNi_1-aO₂ , Li_xCo_bV_1-bO_z, Li_xCo_bFe_1-bO₂ , Li_xMn₂ O_Four , Li_xMn_cCo_2-cO_Four , Li_xMn_cNi_2-cO_Four , Li_xMn_cV_2-cO_Four , Li_xMn_cFe_2-cO_Four (Where x = 0.02 to 1.2, a = 0.1 to 0.9, b = 0.8 to 0.98, c = 1.6 to 1.96, z = 2.1-2. .3).
[0061]
The most preferred lithium-containing transition metal oxide is Li_xCoO₂ , Li_xNiO₂ , Li_xMnO₂ , Li_xCo_aNi_1-aO₂ , Li_xMn₂ O_Four , Li_xCo_bV_1-bO_z(X = 0.02 to 1.2, a = 0.1 to 0.9, b = 0.9 to 0.98, z = 2.01 to 2.3). In addition, the value of x is a value before the start of charging / discharging, and increases / decreases by charging / discharging.
[0062]
The positive electrode active material can be synthesized by a method in which a lithium compound and a transition metal compound are mixed and fired, or by a solution reaction, and the firing method is particularly preferable.
[0063]
Details for firing are described in paragraph 35 of JP-A-6-60,867, JP-A-7-14,579, etc., and these methods can be used. The positive electrode active material obtained by firing may be used after being washed with water, an acidic aqueous solution, an alkaline aqueous solution, or an organic solvent.
[0064]
Further, as a method of chemically inserting lithium ions into the transition metal oxide, a method of synthesis by reacting lithium metal, a lithium alloy or butyl lithium with a transition metal oxide may be used.
[0065]
Although the average particle size of a positive electrode active material is not specifically limited, 0.1-50 micrometers is preferable. The volume of particles of 0.5 to 30 μm is preferably 95% or more. More preferably, the volume occupied by a particle group having a particle size of 3 μm or less is 18% or less of the total volume, and the volume occupied by a particle group of 15 μm or more and 25 μm or less is 18% or less of the total volume. Although it does not specifically limit as a specific surface area, it is 0.01-50m in BET method² / G is preferred, especially 0.2 m² / G-1m² / G is preferred. The pH of the supernatant when 5 g of the positive electrode active material is dissolved in 100 ml of distilled water is preferably 7 or more and 12 or less.
[0066]
When the positive electrode active material is obtained by firing, the firing temperature is preferably 500 to 1500 ° C, more preferably 700 to 1200 ° C, and particularly preferably 750 to 1000 ° C. The firing time is preferably 4 to 30 hours, more preferably 6 to 20 hours, and particularly preferably 6 to 15 hours.
[0067]
The conductive agent used for the electrode mixture may be anything as long as it is an electron conductive material that does not cause a chemical change in the constructed battery. Specific examples include natural graphite such as scaly graphite, scaly graphite, earthy graphite, high-temperature fired bodies such as petroleum coke, coal coke, celluloses, saccharides and mesophase pitch, and graphite such as artificial graphite such as vapor-grown graphite. , Carbon blacks such as acetylene black, furnace black, ketjen black, channel black, lamp black, thermal black, etc., carbon materials such as asphalt pitch, coal tar, activated carbon, mesofuse pitch, polyacene, conductivity of metal fibers, etc. Examples thereof include fibers, metal powders such as copper, nickel, aluminum and silver, conductive whiskers such as zinc oxide and potassium titanate, and conductive metal oxides such as titanium oxide. Among these, graphite and carbon black are preferable, and the particle size is preferably 0.01 μm or more and 20 μm or less, and more preferably 0.02 μm or more and 10 μm or less. These may be used singly or as a mixture.
[0068]
The amount of the conductive agent added to the electrode mixture layer is preferably 6 to 50% by weight, particularly 6 to 30% by weight, based on the negative electrode material or the positive electrode material. In the case of carbon black or graphite, the content is particularly preferably 6 to 20% by weight.
[0069]
A binder is used to hold the electrode mixture. Examples of the binder include polysaccharides, thermoplastic resins, and polymers having rubber elasticity. Preferred binders include starch, carboxymethyl cellulose, cellulose, diacetyl cellulose, methyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, sodium alginate, polyacrylic acid, polyacrylic acid Na, polyvinyl phenol, polyvinyl methyl ether, polyvinyl alcohol, polyvinyl pyrrolidone. Water-soluble polymers such as polyacrylamide, polyhydroxy (meth) acrylate, styrene-maleic acid copolymer, polyvinyl chloride, polytetrafluoroethylene, polyvinylidene fluoride, tetrafluoroethylene-hexafluoropropylene copolymer, vinylidene furo Ride-tetrafluoroethylene-hexafluoropropylene copolymer, polyethylene, polypropylene, ethylene-propylene (Meth) acrylic acid ester copolymers containing (meth) acrylic acid esters such as methyl-diene terpolymer (EPDM), sulfonated EPDM, polyvinyl acetal resin, methyl methacrylate, 2-ethylhexyl acrylate, (meth) acrylic Acid ester-acrylonitrile copolymer, polyvinyl ester copolymer containing vinyl ester such as vinyl acetate, styrene-butadiene copolymer, acrylonitrile-butadiene copolymer, polybutadiene, neoprene rubber, fluoro rubber, polyethylene oxide, polyester polyurethane Resin, polyether polyurethane resin, polycarbonate polyurethane resin, polyester resin, phenol resin, epoxy resin emulsion (latex) or suspension It can be cited.
[0070]
In particular, polyacrylate ester latex, carboxymethyl cellulose, polytetrafluoroethylene, and polyvinylidene fluoride can be used. These binders are preferably those obtained by dispersing fine powders in water, more preferably those having an average particle size of 0.01 to 5 μm in the dispersion, and 0.05 to 1 μm. It is particularly preferable to use one.
[0071]
These binders can be used alone or in combination. When the amount of the binder added is small, the holding power and cohesion of the electrode mixture is weak. If the amount is too large, the electrode volume increases and the capacity per electrode unit volume or unit weight decreases. For this reason, the addition amount of the binder is preferably 1 to 30% by weight, and particularly preferably 2 to 10% by weight.
[0072]
Any filler (filler) may be used as long as it is a fibrous material that does not cause a chemical change in the battery. Usually, olefin polymers such as polypropylene and polyethylene, fibers such as glass and carbon are used. Although the addition amount of a filler is not specifically limited, 0 to 30 weight% is preferable.
[0073]
As the ionic conductive agent, those known as inorganic and organic solid electrolytes can be used, and details are described in the section of the electrolytic solution.
[0074]
A pressure enhancer is a compound that increases the internal pressure of a battery, and carbonates such as lithium carbonate are typical examples.
[0075]
The positive electrode current collector is aluminum, stainless steel, nickel, titanium, or an alloy thereof, and the negative electrode current collector is copper, stainless steel, nickel, titanium, or an alloy thereof. The form of the current collector is foil, expanded metal, punching metal, or wire mesh. In particular, an aluminum foil is preferable for the positive electrode current collector, and a copper foil is preferable for the negative electrode current collector.
[0076]
Next, the configuration of the positive and negative electrodes will be described. The positive and negative electrodes are preferably in a form in which an electrode mixture is applied to both sides of the current collector. In this case, the number of layers per side may be one or may be composed of two or more layers. When the number of layers per side is 2 or more, the positive electrode active material (or negative electrode material) -containing layer may be 2 or more. A more preferable configuration is a case where the layer is composed of a layer containing a positive electrode active material (or negative electrode material) and a layer not containing a positive electrode active material (or negative electrode material).
[0077]
The layer that does not contain the positive electrode active material (or negative electrode material) includes a protective layer for protecting the layer containing the positive electrode active material (or negative electrode material) and a layer containing the divided positive electrode active material (or negative electrode material). And an undercoat layer between the positive electrode active material (or negative electrode material) -containing layer and the current collector. These are collectively referred to as an auxiliary layer in this specification.
[0078]
Particularly preferred is a structure having a protective layer. The protective layer is preferably on both the positive and negative electrodes or on the positive and negative electrodes. In the negative electrode, when lithium is inserted into the negative electrode material in the battery, the negative electrode preferably has a protective layer. The protective layer is composed of at least one layer, and may be composed of a plurality of layers of the same type or different types. Moreover, the form which has a protective layer only in the single side | surface of the mixture layers of both surfaces of a collector may be sufficient. These protective layers are composed of water-insoluble particles and a binder. The binder used when forming the above-mentioned electrode mixture can be used as the binder. As the water-insoluble particles, various kinds of conductive particles and organic and inorganic particles having substantially no conductivity can be used. The solubility of water-insoluble particles in water is 100 ppm or less, preferably insoluble.
[0079]
The proportion of particles contained in the protective layer is preferably 2.5% by weight or more and 96% by weight or less, more preferably 5% by weight or more and 95% by weight or less, and particularly preferably 10% by weight or more and 93% by weight or less.
[0080]
Examples of water-insoluble conductive particles include carbon particles such as metals, metal oxides, metal fibers, carbon fibers, carbon black, and graphite. Among these water-insoluble conductive particles, those having low reactivity with alkali metals, particularly lithium, are preferable, and metal powders and carbon particles are more preferable. The electrical resistivity at 20 ° C. of the elements constituting the particles is 5 × 10⁹ Ω · m or less is preferable.
[0081]
The metal powder is preferably a metal having low reactivity with lithium, that is, a metal that is difficult to form a lithium alloy. Specifically, copper, nickel, iron, chromium, molybdenum, titanium, tungsten, and tantalum are preferable. The shape of these metal powders may be any of acicular, columnar, plate-like, and massive shapes, and the maximum diameter is preferably 0.02 μm or more and 20 μm or less, more preferably 0.1 μm or more and 10 μm or less. These metal powders are preferably those whose surfaces are not excessively oxidized, and when oxidized, heat treatment is preferably performed in a reducing atmosphere.
[0082]
As the carbon particles, a known carbon material used as a conductive material used in combination when the electrode active material is not conductive can be used. Specifically, a conductive agent used for making an electrode mixture is used.
[0083]
Examples of the water-insoluble particles having substantially no conductivity include fine powder of Teflon, SiC, aluminum nitride, alumina, zirconia, magnesia, mullite, forsterite, and steatite. These particles may be used in combination with conductive particles, and are preferably used in an amount of 0.01 to 10 times that of the conductive particles.
[0084]
The positive (negative) electrode sheet can be prepared by applying a positive (negative) electrode mixture onto a current collector, drying, and compressing.
[0085]
The mixture is prepared by mixing a positive electrode active material (or negative electrode material) and a conductive agent, adding a binder (suspension or emulsion of resin powder) and a dispersion medium, kneading and mixing, It can be carried out by dispersing with a mixer / disperser such as a mixer, homogenizer, dissolver, planetary mixer, paint shaker or sand mill. As the dispersion medium, water or an organic solvent is used, but water is preferable. In addition, additives such as a filler, an ionic conductive agent, and a pressure enhancer may be added as appropriate. The pH of the dispersion is preferably 5 to 10 for the negative electrode and 7 to 12 for the positive electrode.
[0086]
Application can be performed by various methods, for example, reverse roll method, direct roll method, blade method, knife method, extrusion method, slide method, curtain method, gravure method, bar method, dip method and squeeze method. I can list them. A method using an extrusion die and a method using a slide coater are particularly preferred. The application is preferably performed at a speed of 0.1 to 100 m / min. Under the present circumstances, the surface state of a favorable coating layer can be obtained by selecting the said application | coating method according to the liquid physical property of a mixture paste, and drying property. When the electrode layer is a plurality of layers, it is preferable to apply the plurality of layers at the same time from the viewpoint of uniform electrode production, production cost, and the like. The thickness, length and width of the coating layer are determined by the size of the battery. The thickness of a typical coating layer is 10 to 1000 μm in a compressed state after drying.
[0087]
The electrode sheet after application is dried and dehydrated by the action of hot air, vacuum, infrared rays, far infrared rays, electron beams and low-humidity air. These methods can be used alone or in combination. The drying temperature is preferably in the range of 80 to 350 ° C, particularly preferably in the range of 100 to 260 ° C.
[0088]
For the compression of the electrode sheet, a generally employed pressing method can be used, but a die pressing method and a calendar pressing method are particularly preferable. The press pressure is not particularly limited, but is 10 kg / cm.²~ 3t / cm²Is preferred. The press speed of the calendar press method is preferably 0.1 to 50 m / min. The pressing temperature is preferably room temperature to 200 ° C.
[0089]
The separator has only to have a high ion permeability, a predetermined mechanical strength, and an insulating thin film. The material is olefin polymer, fluorine polymer, cellulose polymer, polyimide, nylon, glass fiber, alumina fiber. And non-woven fabric, woven fabric, and microporous film are used as forms. In particular, the material is preferably polypropylene, polyethylene, a mixture of polypropylene and polyethylene, a mixture of polypropylene and Teflon, or a mixture of polyethylene and Teflon, and the form is preferably a microporous film. In particular, a microporous film having a pore diameter of 0.01 to 1 μm and a thickness of 5 to 50 μm is preferable. These microporous films may be a single film or a composite film composed of two or more layers having different properties such as the shape, density, and material of the micropores. For example, the composite film which bonded the polyethylene film and the polypropylene film can be mentioned.
[0090]
The electrolytic solution is generally composed of a supporting salt and a solvent. Lithium salt is mainly used as the supporting salt in the lithium secondary battery.
[0091]
Examples of the lithium salt include LiClO._Four , LiBF_Four , LiPF₆ , LiCF_Three SO_Three , LiCF_Three CO₂ , LiAsF₆ , LiSbF₆ , LiB_TenCl_Ten, Lower aliphatic lithium carboxylate, LiAlCl_Four Li salts such as LiCl, LiBr, LiI, chloroborane lithium and lithium tetraphenylborate can be raised, and these can be used alone or in combination. Above all, LiBF_Four And / or LiPF₆ What melt | dissolved is preferable.
[0092]
The concentration of the supporting salt is not particularly limited, but is preferably 0.2 to 3 mol per liter of the electrolytic solution.
[0093]
Examples of the solvent include propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, γ-butyrolactone, methyl formate, methyl acetate, 1,2-dimethoxyethane, tetrahydrofuran 2-methyltetrahydrofuran, dimethyl sulfoxide, 1,3-dioxolane, formamide, dimethylformamide, dioxolane, dioxane, acetonitrile, nitromethane, ethyl monoglyme, phosphoric acid triester, trimethoxymethane, dioxolane derivative, sulfolane, 3-methyl- Examples include aprotic organic solvents such as 2-oxazolidinone, propylene carbonate derivatives, tetrahydrofuran derivatives, ethyl ether, and 1,3-propane sultone. Rukoto can be used as a mixture alone or in combination. Among these, carbonate-based solvents are preferable, and it is particularly preferable to use a mixture of a cyclic carbonate and an acyclic carbonate. As the cyclic carbonate, ethylene carbonate and propylene carbonate are preferable. Moreover, as an acyclic carbonate, diethyl carbonate, dimethyl carbonate, and methyl ethyl carbonate are preferable.
[0094]
As the electrolytic solution, LiCF was added to an electrolytic solution appropriately mixed with ethylene carbonate, propylene carbonate, 1,2-dimethoxyethane, dimethyl carbonate or diethyl carbonate._Three SO_Three LiClO_Four , LiBF_Four And / or LiPF₆ An electrolytic solution containing is preferable. In particular, in a mixed solvent of at least one of propylene carbonate or ethylene carbonate and at least one of dimethyl carbonate or diethyl carbonate, LiCF_Three SO_Three LiClO_Four Or LiBF_Four At least one salt selected from the group consisting of LiPF and LiPF₆ An electrolytic solution containing is preferable. The amount of the electrolyte added to the battery is not particularly limited, and can be used depending on the amount of the positive electrode material or the negative electrode material or the size of the battery.
[0095]
In addition to the electrolytic solution, the following solid electrolyte can be used in combination.
The solid electrolyte is classified into an inorganic solid electrolyte and an organic solid electrolyte.
Well-known inorganic solid electrolytes include Li nitrides, halides, oxyacid salts, and the like. Among them, Li_Three N, LiI, Li_Five NI₂ , Li_Three N-LiI-LiOH, Li_Four SiO_Four , Li_Four SiO_Four -LiI-LiOH, x Li_Three PO_Four − (1-x) Li_Four SiO_Four , Li₂ SiS_Three In addition, phosphorus sulfide compounds are effective.
[0096]
In the organic solid electrolyte, a polyethylene oxide derivative or a polymer containing the derivative, a polypropylene oxide derivative or a polymer containing the derivative, a polymer containing an ion dissociation group, a mixture of a polymer containing an ion dissociation group and the above aprotic electrolyte, phosphoric acid A polymer matrix material containing an ester polymer and an aprotic polar solvent is effective. Furthermore, there is a method of adding polyacrylonitrile to the electrolytic solution. A method of using an inorganic and organic solid electrolyte in combination is also known.
[0097]
Further, other compounds may be added to the electrolyte for the purpose of improving discharge and charge / discharge characteristics. For example, pyridine, pyrroline, pyrrole, triphenylamine, phenylcarbazole, triethyl phosphite, triethanolamine, cyclic ether, ethylenediamine, n-glyme, hexaphosphoric triamide, nitrobenzene derivative, sulfur, quinoneimine dye, N-substituted oxazolidinone and N , N′-substituted imidazolidinone, ethylene glycol dialkyl ether, quaternary ammonium salt, polyethylene glycol, pyrrole, 2-methoxyethanol, AlCl_Three , Conductive polymer electrode active material monomers, triethylene phosphoramide, trialkylphosphine, morpholine, aryl compounds having a carbonyl group, crown ethers such as 12-crown-4, hexamethylphosphoric triamide and 4-alkyl Examples thereof include morpholine, bicyclic tertiary amine, oil, quaternary phosphonium salt, tertiary sulfonium salt and the like. Particularly preferred is a case where triphenylamine and phenylcarbazole are used alone or in combination.
[0098]
In order to make the electrolyte nonflammable, a halogen-containing solvent such as carbon tetrachloride or ethylene trifluoride chloride can be contained in the electrolyte. In addition, carbon dioxide gas can be included in the electrolyte in order to make it suitable for high-temperature storage.
[0099]
It is desirable that the electrolytic solution contains as little water and free acid as possible. For this reason, the raw material of the electrolytic solution is preferably one that has been sufficiently dehydrated and purified. The electrolyte solution is preferably adjusted in dry air or an inert gas with a dew point of minus 30 ° C. or less. The amount of water and free acid content in the electrolytic solution is 0.1 to 500 ppm, more preferably 0.2 to 100 ppm.
[0100]
The entire amount of the electrolytic solution may be injected once, but it is preferable to inject it in two or more times. When injecting in two or more times, each solution may have the same composition but a different composition (for example, a non-aqueous solvent or a non-aqueous solvent having a higher viscosity than the solvent after injecting a solution in which a lithium salt is dissolved in the non-aqueous solvent). Or a solution in which a lithium salt is dissolved in a solvent or a non-aqueous solvent may be injected). In order to shorten the time for injecting the electrolyte, etc., the battery can may be decompressed, or centrifugal force or ultrasonic waves may be applied to the battery can.
[0101]
Battery can and battery cover are made of nickel-plated steel plate, stainless steel plate (SUS304, SUS304L, SUS304N, SUS316, SUS316L, SUS430, SUS444, etc.), nickel-plated stainless steel plate (same as above), aluminum or an alloy thereof Nickel, titanium, and copper, and the shapes are a perfect circular cylinder, an elliptical cylinder, a square cylinder, and a rectangular cylinder. In particular, when the battery can also serves as the negative electrode terminal, a stainless steel plate and a nickel-plated steel plate are preferred, and when the battery can also serves as the positive electrode terminal, a stainless steel plate, aluminum or an alloy thereof is preferred. The shape of the battery can may be any of buttons, coins, sheets, cylinders, and corners.
[0102]
A safety valve can be used for the sealing plate as a countermeasure against an increase in the internal pressure of the battery can. In addition, a method of cutting a member such as a battery can or a gasket can be used. In addition, various conventionally known safety elements (for example, fuses, bimetals, PTC elements, etc. as overcurrent prevention elements) may be provided.
[0103]
For the lead plate, a metal having electrical conductivity (for example, iron, nickel, titanium, chromium, molybdenum, copper, aluminum, or the like) or an alloy thereof can be used. As a welding method for the battery lid, battery can, electrode sheet, and lead plate, a known method (eg, direct current or alternating current electric welding, laser welding, ultrasonic welding) can be used. As the sealing agent for sealing, a conventionally known compound or mixture such as asphalt can be used.
[0104]
The gasket is made of an olefin polymer, a fluorine polymer, a cellulose polymer, polyimide, polyamide, or polyester as a material, and is preferably an olefin polymer or a polyester polymer in terms of organic solvent resistance and low moisture permeability. In particular, the olefin polymer is preferably a propylene-based polymer, and is preferably a polypropylene or a block copolymer of propylene and ethylene. Of the polyester polymers, polybutylene terephthalate is preferred.
[0105]
The battery assembled as described above is preferably subjected to an aging treatment. The aging treatment includes pre-treatment, activation treatment, post-treatment, and the like, whereby a battery with high charge / discharge capacity and excellent cycleability can be produced. The pretreatment is a treatment for homogenizing the distribution of lithium in the electrode. For example, control of lithium dissolution, temperature control to make the lithium distribution uniform, oscillation and / or rotation treatment, optional charging / discharging A combination is made. The activation process is a process for inserting lithium into the negative electrode of the battery body, and it is preferable to insert 50 to 120% of the amount of lithium inserted during actual use charging of the battery. The post-processing is processing for sufficient activation processing, and includes storage processing for uniform battery reaction, charge / discharge processing for determination, and the like, which can be arbitrarily combined.
[0106]
The battery is covered with an exterior material as necessary. Examples of the exterior material include a heat-shrinkable tube, an adhesive tape, a metal film, paper, cloth, paint, and a plastic case. Further, at least a part of the exterior may be provided with a portion that changes color by heat so that the heat history during use can be known.
[0107]
A plurality of batteries are assembled in series and / or in parallel as required, and stored in a battery pack. In addition to safety elements such as positive temperature coefficient resistors, temperature fuses, fuses and / or current interrupting elements, the battery pack also requires safety circuits (monitoring the voltage, temperature, current, etc. of each battery and / or the entire battery pack) In this case, a circuit having a function of interrupting current may be provided. In addition to the positive and negative terminals of the entire assembled battery, the battery pack should be provided with the positive and negative terminals of each battery, the entire assembled battery, the temperature detection terminal of each battery, the current detection terminal of the entire assembled battery, etc. as external terminals. You can also. The battery pack may incorporate a voltage conversion circuit (such as a DC-DC converter). The connection of each battery may be fixed by welding a lead plate, or may be fixed so that it can be easily attached and detached with a socket or the like. Further, the battery pack may be provided with display functions such as the remaining battery capacity, the presence / absence of charging, and the number of uses.
[0108]
Batteries are used in various devices. In particular, video movies, portable video decks with built-in monitors, movie cameras with built-in monitors, digital cameras, compact cameras, single-lens reflex cameras, film with lenses, notebook computers, notebook-type word processors, electronic notebooks, mobile phones, cordless phones, whiskers, It is preferably used for electric tools, electric mixers, automobiles and the like.
[0109]
【Example】
Hereinafter, the present invention will be described in more detail with reference to specific examples. However, the present invention is not limited to the examples unless it exceeds the gist of the invention.
[0110]
(Example-1)
SnB as negative electrode material_0.2P_0.5K_0.1Mg_0.1Ge_0.1O_2.886 parts by weight (average particle size 7.5 μm) and 3 parts by weight of acetylene black as a conductive agent and 6 parts by weight of graphite are mixed. 4 parts by weight of polyvinylidene fluoride and 1 part by weight of carboxymethylcellulose were added to the mixture as a binder, and kneaded using water as a medium to obtain a negative electrode mixture slurry. The slurry was coated on both sides of a 10 μm thick copper foil (current collector) using an extrusion coater and dried to obtain a negative electrode mixture sheet.
[0111]
Next, 79 parts by weight of α-alumina, 18 parts by weight of graphite, and 3 parts by weight of carboxymethyl cellulose were added with water as a medium and kneaded to obtain an auxiliary layer slurry. The slurry was coated on the negative electrode mixture sheet, dried, and then compression molded by a calender press to prepare a strip-shaped negative electrode sheet precursor having a thickness of 98 μm, a width of 55 mm, and a length of 520 mm.
[0112]
After spot-welding a nickel lead plate to this negative electrode sheet precursor, it was dehydrated and dried at 230 ° C. for 30 minutes in air having a dew point of −40 ° C. or lower.
[0113]
40 sheets of 40 μm-thick lithium foil (purity 99.5%) cut into 4 mm × 55 mm were bonded to both sides of the sheet, respectively. For crimping, once the lithium foil is transferred to a 300 mm diameter polyethylene roller, both sides of the sheet are simultaneously 5 kg / cm.²Was carried out while applying a pressure of. At this time, the coverage of the negative electrode sheet with lithium foil was 40%.
[0114]
LiCoO as positive electrode active material₂Is mixed in a ratio of 3 parts by weight of acetylene black and 6 parts by weight of graphite as a conductive agent. To the mixture, 3 parts by weight of Nipo1820B (manufactured by Zeon Corporation) and 1 part by weight of carboxymethylcellulose were added as a binder, and kneaded with water as a medium to obtain a positive electrode mixture slurry.
[0115]
As shown in FIG. 1, the slurry was applied to both sides of an aluminum foil (current collector) having a thickness of 20 μm using an extrusion type coater, dried and then compression-molded by a calendar press machine to have a thickness of 260 μm, A belt-like positive electrode sheet 3 having a width of 53 mm and a length of 445 mm was prepared. After welding the lead plate 8 made of aluminum to the end of the positive electrode sheet, it was dehydrated and dried at 230 ° C. for 30 minutes in dry air having a dew point of −40 ° C. or lower.
[0116]
The heat-treated positive electrode sheet 3, the microporous polyethylene / polypropylene film separator 4, the negative electrode sheet 2, and the separator 4 were laminated in this order, and this was wound in a spiral shape.
[0117]
This wound body was housed in a nickel-plated iron-bottomed cylindrical battery 1 serving also as a negative electrode terminal. Furthermore, 1 mol / liter LiPF is used as the electrolyte.₆(2 to 8 weight ratio mixed solution of ethylene carbonate and diethyl carbonate) was poured into the battery can 1 while cooling the battery can 1 to 0 ° C. A battery lid 13 having a positive electrode terminal was caulked through a gasket 7 to produce a cylindrical battery having a height of 67 mm and an outer diameter of 17 mm. The positive electrode terminal 13 was connected to the positive electrode sheet 3 and the battery can 1 was connected to the negative electrode sheet 2 in advance by a lead terminal. A current interrupting device including an explosion-proof valve body 9 and a current interrupting switch 10 is provided at the sealing portion of the battery.
[0118]
In addition, the space volume inside a battery was suppressed with the injection volume of electrolyte solution. Twenty batteries each having the same space volume were prepared. After caulking, after aging for 2 hours at 0 ° C. and 15 hours at 25 ° C., 0.4 mA / cm at 25 ° C.²After charging at a constant voltage up to 3.1 V, the mixture was further aged at 50 ° C. for 2 weeks. After that, 1mA / cm²To 4.1V and then 1mA / cm²Was discharged to 2.8V. With respect to storage characteristics, 10 batteries were recharged to 4.1 V, stored at 90 ° C. for 3 days, and examined for the operation of a breaker (current interrupter). Further, 10 batteries were stored at 105 ° C. for 1 day, and it was examined whether or not there was a leakage of the electrolyte. The results are shown in [Table 1]. The denominator in the table indicates the number of non-defective products, and the numerator indicates the number of defective products.
[0119]
[Table 1]

[0120]
As is clear from [Table 1], V₁/ V₂In the battery (level a), which is smaller than 2%, two defects (liquid leakage) occurred in the liquid leakage test. Also, V₁/ V₂Batteries with a value greater than 30% (level b) produced 3 defects (breaker operation) in the breaker operation test. V₁/ V₂However, in the batteries (levels A, B, C, and D) of 2 to 30%, no failure occurred and the storage characteristics were satisfied.
[0121]
(Example-2)
Sn as negative electrode material_0.8Si_0.5B_0.3P_0.2Al_0.1O_2.9A battery was prepared in the same manner as in Example 1 except that the battery size was 18650 (outer diameter: 18 mm, height: 65 mm), and storage characteristics were similarly evaluated.
[0122]
The results are shown in [Table 2]. The denominator in the table indicates the number of non-defective products, and the numerator indicates the number of defective products.
[0123]
[Table 2]

[0124]
In [Table 2], as in [Table 1], V₁/ V₂In the battery (level c), which is smaller than 2%, one defect (liquid leakage) occurred in the liquid leakage test. Also, V₁/ V₂Batteries with a value greater than 30% (level d) produced two defects (breaker operation) in the breaker operation test. V₁/ V₂However, in the batteries (levels E, F, G, and H) of 2 to 30%, no defect occurred and the storage characteristics were satisfied. V₁/ V₂Is preferably 2 to 30%.
[0125]
【The invention's effect】
By making the space volume inside the battery after sealing with the electrolyte injected to be 2% or more and 30% or less of the space volume when the electrolyte is not injected, it has excellent storage characteristics and good cycleability. A sealed nonaqueous electrolyte secondary battery can be obtained.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a cylindrical battery.
[Explanation of symbols]
1 Battery can
2 Negative electrode
3 Positive electrode
4 Separator
5 Lower insulation plate
6 Upper insulation plate
7 Gasket
8 Positive lead
9 Explosion-proof valve body
10 Current cut-off switch
10a First conductor
10b Second conductor
10c Insulation ring
11 PTC ring
13 Terminal cap
15 Welding plate
16 Insulation cover

Claims (4)

A positive electrode sheet having a layer mainly composed of lithium-containing metal oxide,
A negative electrode sheet having a layer in which the lithium mainly absorbing and releasing negative electrode material capable
A non-aqueous electrolyte containing a lithium salt ;
In a non-aqueous electrolyte secondary battery comprising a separator,
When the positive electrode sheet, the negative electrode sheet, and the separator are stacked or wound and inserted into the battery can, the nonaqueous electrolyte is injected, and the space volume (V1) inside the battery after sealing the battery can and the electrolyte are not injected The ratio of the volume to the space volume (V2) (percentage of (V1 / V2)) is 2% to 30%,
The amount of water in the electrolyte is 0.1 to 500 ppm,
In addition, the battery can has a pressure sensitive current interrupting device,
The current interrupt device includes an explosion-proof valve and a current interrupt switch,
A sealed nonaqueous electrolyte secondary battery, wherein when the internal pressure of the battery rises to 10 to 15 kgf / cm ² , the explosion-proof valve body of the explosion-proof valve is deformed and the current cutoff switch cuts off the current .   2. The positive electrode sheet and the negative electrode sheet are characterized in that the porosity is controlled to 10% or more and 40% or less by applying pressure after applying an electrode mixture to a current collector. Sealed non-aqueous electrolyte secondary battery.   The solvent of the non-aqueous electrolyte solution containing a lithium salt and having a water content of 0.1 to 500 ppm is a mixture of a cyclic carbonate and a non-cyclic carbonate. Sealed non-aqueous electrolyte secondary battery.   Either or both of the positive electrode sheet and the negative electrode sheet have a protective layer,
  The particles contained in the protective layer are at least one of Teflon fine powder, SiC, aluminum nitride, alumina, zirconia, magnesia, mullite, forsterite, and steatite. The sealed nonaqueous electrolyte secondary battery according to any one of the above.

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