JP4136260B2 - Non-aqueous electrolyte battery - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a nonaqueous electrolyte battery in which a positive electrode including a positive electrode active material, a negative electrode, and a nonaqueous electrolyte including a lithium salt are housed in an exterior body.
[0002]
[Prior art]
In recent years, as a power source for portable devices, development of a battery that is small, lightweight, and has a high energy density has been desired. In such circumstances, a non-aqueous electrolyte or a gel-like solid polymer is used as an electrolyte, and lithium oxidation is performed. Non-aqueous electrolyte batteries using reduction have been used.
[0003]
In such a battery, lithium cobaltate is mainly used as a positive electrode material, but the charge / discharge capacity and charge / discharge efficiency are gradually lowered by repeated charge / discharge, and a sufficient cycle life cannot be obtained. is there. The reason why the charge / discharge capacity and charge / discharge efficiency are reduced is that, due to a change in the crystal structure of the positive electrode active material, an irreversible change of the active material occurs in part, and the positive electrode potential is the standard. It is conceivable that the electrolytic solution is decomposed by charging that is higher than the value or charging that is lower than the reference value. For this reason, as described below, attempts have been made to solve the above problems by partially replacing various metal elements in the positive electrode active material.
[0004]
For example, as disclosed in JP-A-4-329267 and JP-A-5-13082, a titanium compound dissolved in lithium cobaltate is used as the positive electrode active material, or JP-A-4-319260. As disclosed in the publication, a solid solution of zirconium in lithium cobaltate is used as a positive electrode active material. A battery using a melted material or the like as a positive electrode active material has been proposed. In a battery using these positive electrode active materials, the cycle characteristics can be improved by substituting another metal element with lithium cobalt oxide as a partial element. However, since the heat generation start temperature is lowered, there is a problem that safety is lowered and gas generation due to reaction with the electrolyte is remarkably increased.
[0005]
Also, in recent years, with the progress of thinning of batteries and improvement of energy density with the miniaturization of portable devices, ion batteries and gel polymer batteries using a laminate outer package have been proposed. Since such a battery is deformed by a slight increase in the internal pressure of the battery, in addition to the battery performance, swelling of the battery due to the generation of a large amount of gas during charge / discharge and high-temperature storage is a major problem. Therefore, it has become necessary to develop a technique for reducing gas generation in order to prevent the battery from swelling.
[0006]
[Problems to be solved by the invention]
The present invention has been made in view of the above circumstances, and provides a non-aqueous electrolyte battery capable of improving safety and reducing gas generation without deteriorating battery characteristics such as cycle characteristics. Objective.
[0007]
[Means for Solving the Problems]
  In order to achieve the above object, the invention according to claim 1 is a nonaqueous electrolyte in which a positive electrode including a positive electrode active material, a negative electrode, and a nonaqueous electrolyte including a lithium salt are housed in an outer package. In the battery, as the positive electrode active material, LiCo_xM_yAl_zO₂[M is selected from the group consisting of Nb, Pb, Zn, ZrA lithium-containing composite oxide represented by 0.90 ≦ x <1, 0 <y ≦ 0.05, 0 <z ≦ 0.05, x + y + z = 1] is used.
[0008]
As described above, when lithium metal cobalt oxide in which other metal element M and Al are dissolved is used as the positive electrode active material, only other metal element M is added to lithium cobalt oxide in battery characteristics such as cycle characteristics. Solid solution (specifically, LiCo_xM_yO₂When the cathode active material is obtained by dissolving only the other metal element M in lithium cobaltate as the cathode active material. In comparison, safety can be improved and gas generation can be reduced. In particular, LiCo_xM_yAl_zO₂In the case of 0.94 ≦ x <1, 0.00001 ≦ y ≦ 0.05, and 0.0001 ≦ z ≦ 0.05, the above effect is further exhibited.
[0009]
LiCo_xM_yAl_zO₂In 0.95 ≦ x, y ≦ 0.05, and z ≦ 0.05, the amount of Co is relatively small when the amount of M or Al is too large, so that the battery capacity decreases. It is to do. On the other hand, LiCo_xM_yAl_zO₂In this case, particularly preferable ranges of y and z are 0.00001 ≦ y and 0.0001 ≦ z. When the amount of M or Al is smaller than this, safety is improved and gas generation is reduced. This is because it may not be fully demonstrated.
[0010]
  The invention according to claim 2 is the invention according to claim 1, wherein the LiCo_xM_yAl_zO₂As MNb and ZrIt is characterized by being at least one kind selected from.
[0011]
  When lithium cobaltate in which only another metal element M is dissolved is used as the positive electrode active material, M isNb or ZrHowever, compared with the case where M is an element other than these elements, the battery characteristics such as the cycle characteristics are remarkably improved, but on the other hand, the safety is lowered and the gas generation due to the reaction with the electrolyte is caused. Invite an increase. Therefore, lithium cobaltateNb or ZrIn addition to using Al as a positive electrode active material, it is possible to improve the safety while maintaining the same battery characteristics as those obtained by dissolving only the other metal element M in lithium cobaltate. And reduction of gas generation.
[0012]
The invention according to claim 3 is the invention according to claim 1 or 2, wherein the electrolyte is a gel-like solid polymer.
[0013]
When a gel-like solid polymer is used as the electrolyte, the oxidation resistance of the gel-like solid polymer is excellent when not only other metal element M but also Al is dissolved in lithium cobalt oxide. Therefore, in particular, battery characteristics such as cycle characteristics and safety are improved, and gas generation due to reaction with the electrolyte can be remarkably suppressed.
[0014]
The invention described in claim 4 is characterized in that, in the invention described in claim 1, 2 or 3, an exterior body that is deformed by a slight increase in battery internal pressure is used as the exterior body.
[0015]
In a battery using such a soft laminate outer package, rupture or leakage due to deformation of the battery is likely to occur. However, if the amount of gas generated is significantly reduced as described above, rupture or leakage can be suppressed.
[0016]
According to a fifth aspect of the invention, in the first, second, third, or fourth aspect of the invention, an aluminum laminate outer package is used as the outer package that is deformed by the slight increase in battery internal pressure. .
[0017]
DETAILED DESCRIPTION OF THE INVENTION
The 1st form and 2nd form of this invention are demonstrated below.
[0018]
(First form)
The 1st form of this invention is demonstrated below based on FIGS. 1-4.
[0019]
1 is a front view of the nonaqueous electrolyte battery according to the first embodiment, FIG. 2 is a cross-sectional view taken along line AA in FIG. 1, and FIG. 3 is a laminate outer package used for the nonaqueous electrolyte battery according to the first embodiment FIG. 4 is a perspective view of a power generation element used in the nonaqueous electrolyte battery according to the first embodiment.
[0020]
  As shown in FIG. 2, the thin battery of the present invention has a power generation element 1, and the power generation element 1 is disposed in a storage space 2. As shown in FIG. 1, the storage space 2 is formed by sealing the upper and lower ends and the center of the aluminum laminate outer package 3 with sealing portions 4a, 4b, and 4c, respectively. In the storage space 2, an electrolytic solution in which lithium hexafluorophosphate (LiPF6) is dissolved at a rate of 1 mol / l in an equal volume mixed solvent of ethylene carbonate (EC) and diethyl carbonate (DEC) is injected. ing. Further, as shown in FIG. 4, the power generation element 1 includes LiCox My Alz O 2 [M is selected from the group consisting of Nb, Pb, Zn, ZrA positive electrode 5 having at least one kind, and 0.90 ≦ x <1, 0 <y ≦ 0.05, 0 <z ≦ 0.05, x + y + z = 1], and a graphite-based carbon material as an active material It is produced by winding a negative electrode 6 to be separated and a separator that separates both electrodes into a flat spiral shape (not shown in FIG. 4).
[0021]
Further, as shown in FIG. 3, the specific structure of the aluminum laminate outer package 3 is such that adhesive layers 12 and 12 (thickness: 5 μm) made of modified polypropylene are formed on both sides of the aluminum layer 11 (thickness: 30 μm), respectively. ) Through which the resin layers 13 and 13 (thickness: 30 μm) made of polypropylene are bonded.
[0022]
Further, the positive electrode 5 is connected to a positive electrode lead 7 made of aluminum, and the negative electrode 6 is connected to a negative electrode lead 8 made of copper, so that chemical energy generated inside the battery can be taken out as electric energy to the outside. .
[0023]
Here, the battery having the above structure was produced as follows.
[0024]
  First, lithium carbonate, cobalt oxide powder, aluminum oxide, and M [M is at least one selected from the group consisting of Nb, Pb, Zn, Zr] metal oxide or hydroxide in a predetermined ratio And LiCox My Alz O2 (0.90 ≦ x <1, 0 <y ≦ 0.05, 0 <z ≦ 0.05) by firing at 850 ° C. for 24 hours in an oxygen atmosphere. A positive electrode active material comprising a lithium-containing composite oxide was obtained. The positive electrode active material synthesized in this way, graphite, carbon black, and fluororesin-based binder were mixed at a weight ratio of 90: 3: 2: 5 to prepare a positive electrode mixture. The positive electrode mixture was applied to both surfaces of the aluminum foil, dried, and then rolled to prepare the positive electrode 5.
[0025]
On the other hand, a graphite-based carbon material and a fluororesin-based binder are mixed at a weight ratio of 90:10 to prepare a negative electrode mixture, and then this negative electrode mixture is applied to both sides of the copper foil and dried. The negative electrode 6 was produced by post-rolling.
[0026]
Next, after attaching the positive electrode lead 7 or the negative electrode lead 8 to the positive and negative electrodes 5 and 6 manufactured as described above, the positive and negative electrodes 5 and 6 are spirally wound through a separator to manufacture the power generation element 1. Further, this power generation element 1 was inserted into the aluminum laminate outer package 3. Finally, an electrolyte was injected into the aluminum laminate outer package 3, and the aluminum laminate outer package 3 was further sealed to produce a battery. In addition, as electrolyte solution, lithium hexafluorophosphate (LiPF) was mixed in an equal volume mixed solvent of ethylene carbonate (EC) and diethyl carbonate (DEC).₆) Was dissolved at a rate of 1 mol / l.
[0027]
(Second form)
A battery was fabricated in the same manner as in the first embodiment except that a gel solid polymer was used as the electrolyte. Specifically, it is as follows.
[0028]
First, after the power generation element produced in the same manner as described above was inserted into an aluminum laminate outer package, an equal volume mixed solvent of polyethylene glycol diacrylate (molecular weight: 1000) as a prepolymer and EC and DEC was inserted into the aluminum laminate outer package. LiPF₆3 mol / l was mixed at a weight ratio of 1:10, and 3 ml of a mixture obtained by adding 5000 ppm of t-hexylperoxypivalate as a polymerization initiator to the mixture was injected. Then, the battery was produced by heat-processing at 60 degreeC for 3 hours, and making it harden | cure.
[0029]
  In the above embodiment, only one type of metal is used as M. However, the present invention is not limited to this.2 or more metalsThe effect of the present invention can also be obtained using.
[0030]
Moreover, although the aluminum laminate exterior body is illustrated as an example of the exterior body which deform | transforms with a slight raise of battery internal pressure, this invention is not limited to such an exterior body.
[0031]
Furthermore, as the negative electrode material used in the present invention, lithium metal, lithium alloy and the like are preferably used in addition to the above carbon material. Furthermore, the solvent of the electrolytic solution is not limited to the above, and examples thereof include ethylene carbonate and dimethyl carbonate, methyl ethyl carbonate, tetrahydrofuran, 1,2-dimethoxyethane, 1,3-dioxolane, 2-methoxytetrahydrofuran, diethyl ether and the like. A solvent in which a low-viscosity low-boiling solvent is mixed at an appropriate ratio can be used. In addition, as the solute of the electrolytic solution, the above LiPF₆In addition, LiN (SO₂C₂F_Five)₂, LiAsF₆LiClO_Four, LiBF_Four, LiCF_ThreeSO_ThreeEtc. can be used.
[0032]
In addition, as the gel-like solid polymer, in addition to polyethylene glycol diacrylate, a polyether solid polymer, a polycarbonate solid polymer, a polyacrylonitrile solid polymer, and a co-polymer comprising two or more of these. A polymer, a cross-linked polymer material, a fluorine-based solid polymer such as polyvinylidene fluoride, a lithium salt, or an electrolytic solution can be used in combination.
[0033]
【Example】
                            (First embodiment)
[referenceExamples 1-5]
  M as transition metal element and periodic table II A, III B, IV B, V Select Ti from group B elements (excluding Al)And LiCo_xM_yAl_zO₂In the same manner as the method described in the first embodiment, x, y, and z are changed in the range of 0.90 ≦ x <1, 0 <y ≦ 0.05, and 0 <z ≦ 0.05. Was made.
[0034]
  The batteries produced in this way are hereinafter respectivelyreferenceThese are referred to as batteries A1 to A5.
[0035]
Moreover, the same positive electrode as the said battery and the negative electrode (reference electrode) which consists of metal lithium foil were immersed in the same electrolyte solution as the said battery, and the battery for a test was produced.
[0036]
  The batteries produced in this way are hereinafter respectivelyreferenceThese are referred to as batteries A101 to A105.
[Examples 6 to 10]
Nb is used as M, and x, y and z in LiCox My Alz O2 are changed in the range of 0.90 ≦ x <1, 0 <y ≦ 0.05, 0 <z ≦ 0.05, and the first A battery was manufactured by the same method as that shown in the above embodiment.
[0037]
The batteries thus produced are hereinafter referred to as present invention batteries A6 to A10, respectively.
[0038]
Moreover, the same positive electrode as the said battery and the negative electrode (reference electrode) which consists of metal lithium foil were immersed in the same electrolyte solution as the said battery, and the battery for a test was produced.
[0039]
  The batteries thus produced are hereinafter referred to as the present invention batteries.A106 to A110Called.
Examples 11 to 15 Pb is used as M, and x, y, and z in LiCox My Alz O2 are in the range of 0.90 ≦ x <1, 0 <y ≦ 0.05, 0 <z ≦ 0.05. In other words, a battery was fabricated by the same method as that shown in the first embodiment.
[0040]
The batteries thus produced are hereinafter referred to as invention batteries A11 to A15, respectively.
[0041]
Moreover, the same positive electrode as the said battery and the negative electrode (reference electrode) which consists of metal lithium foil were immersed in the same electrolyte solution as the said battery, and the battery for a test was produced.
[0042]
The batteries thus produced are hereinafter referred to as invention batteries A111 to A115, respectively.
[Examples 16 to 20]
Zn is used as M, and LiCo_xM_yAl_zO₂In the same manner as the method described in the first embodiment, x, y, and z are changed in the range of 0.90 ≦ x <1, 0 <y ≦ 0.05, and 0 <z ≦ 0.05. Was made.
[0043]
The batteries thus produced are hereinafter referred to as invention batteries A16 to A20, respectively.
[0044]
Moreover, the same positive electrode as the said battery and the negative electrode (reference electrode) which consists of metal lithium foil were immersed in the same electrolyte solution as the said battery, and the battery for a test was produced.
[0045]
The batteries thus produced are hereinafter referred to as present invention batteries A116 to A120, respectively.
Example 21
Zr is used as M, and LiCo_xM_yAl_zO₂A battery was fabricated in the same manner as in the first embodiment, with x, y, and z in x = 0.98, y = 0.01, and z = 0.01.
[0046]
The battery thus produced is hereinafter referred to as the present invention battery A21.
[0047]
Moreover, the same positive electrode as the said battery and the negative electrode (reference electrode) which consists of metal lithium foil were immersed in the same electrolyte solution as the said battery, and the battery for a test was produced.
[0048]
The battery thus produced is hereinafter referred to as the present invention battery A121.
[Comparative Examples 1 and 2]
LiCo_xM_yAl_zO₂Except that x, y, and z are x = 0.8, y = 0.1, z = 0.1, and x = 0.99, y = 0.01, and z = 0, respectively. A battery was produced in the same manner as in Example 1.
[0049]
The batteries thus produced are hereinafter referred to as comparative batteries X1 and X2, respectively.
[0050]
Moreover, the same positive electrode as the said battery and the negative electrode (reference electrode) which consists of metal lithium foil were immersed in the same electrolyte solution as the said battery, and the battery for a test was produced.
[0051]
The batteries thus produced are hereinafter referred to as comparative batteries X101 and X102, respectively.
[Comparative Examples 3 and 4]
LiCo_xM_yAl_zO₂In Example 6 except that x, y, and z are x = 0.8, y = 0.1, z = 0.1, and x = 0.99, y = 0.01, and z = 0. A battery was produced in the same manner as shown in 1.
[0052]
The batteries thus produced are hereinafter referred to as comparative batteries X3 and X4, respectively.
[0053]
Moreover, the same positive electrode as the said battery and the negative electrode (reference electrode) which consists of metal lithium foil were immersed in the same electrolyte solution as the said battery, and the battery for a test was produced.
[0054]
The batteries thus produced are hereinafter referred to as comparative batteries X103 and X104, respectively.
[Comparative Examples 5 and 6]
LiCo_xM_yAl_zO₂In Example 11 except that x, y, and z are x = 0.8, y = 0.1, z = 0.1, and x = 0.99, y = 0.01, and z = 0. A battery was produced in the same manner as shown in 1.
[0055]
The batteries thus produced are hereinafter referred to as comparative batteries X5 and X6, respectively.
[0056]
Moreover, the same positive electrode as the said battery and the negative electrode (reference electrode) which consists of metal lithium foil were immersed in the same electrolyte solution as the said battery, and the battery for a test was produced.
[0057]
The batteries thus produced are hereinafter referred to as comparative batteries X105 and X106, respectively.
[Comparative Examples 7 and 8]
LiCo_xM_yAl_zO₂In Example 16 except that x, y, and z are x = 0.8, y = 0.1, z = 0.1, and x = 0.99, y = 0.01, and z = 0. A battery was produced in the same manner as shown in 1.
[0058]
The batteries thus produced are hereinafter referred to as comparative batteries X7 and X8, respectively.
[0059]
Moreover, the same positive electrode as the said battery and the negative electrode (reference electrode) which consists of metal lithium foil were immersed in the same electrolyte solution as the said battery, and the battery for a test was produced.
[0060]
The batteries thus produced are hereinafter referred to as comparative batteries X107 and X108, respectively.
[Comparative Example 9]
LiCo_xM_yAl_zO₂A battery was fabricated in the same manner as in Example 1 except that x, y, and z in x were set to x = 1, y = 0, and z = 0.
[0061]
The battery thus produced is hereinafter referred to as comparative battery X9.
[0062]
Moreover, the same positive electrode as the said battery and the negative electrode (reference electrode) which consists of metal lithium foil were immersed in the same electrolyte solution as the said battery, and the battery for a test was produced.
[0063]
The battery thus produced is hereinafter referred to as comparative battery X109.
[Comparative Example 10]
LiCo_xM_yAl_zO₂A battery was fabricated in the same manner as in Example 21 except that x, y, and z in x were set to x = 0.99, y = 0.01, and z = 0.
[0064]
The battery thus produced is hereinafter referred to as comparative battery X10.
[0065]
Moreover, the same positive electrode as the said battery and the negative electrode (reference electrode) which consists of metal lithium foil were immersed in the same electrolyte solution as the said battery, and the battery for a test was produced.
[0066]
  The battery thus produced is hereinafter referred to as comparative battery X110.
[Experiment 1]
  the aboveReference batteries A101 to A105, invention batteries A106 to A120Since the charge capacity per unit weight in the positive electrode active material was examined using the comparative batteries X101 to X109, the results are shown in Tables 1 and 2.
[0067]
[Table 1]
[0068]
[Table 2]
As apparent from Table 1 and Table 2 above, LiCo_xM_yAl_zO₂As the sum of the values of y and z in (x + y + z = 1) increases, it is recognized that the charge capacity per unit weight decreases, and as a result, the weight energy density also decreases. This is considered due to the fact that the amount of Co decreases as the sum of the values of y and z increases.
[0069]
  Therefore, from the viewpoint of weight energy density, LiCo_xM_yAl_zO₂X, y and z in the formula are 0.9 ≦ x, y ≦ 0.05, z ≦ 0.05 (particularly 0.94 ≦ x, y ≦ 0.05, z ≦ 0.05). It turns out to be desirable.
[Experiment 2]
  the aboveReference batteries A1 to A5, invention batteries A6 to A20Since the cycle characteristics, the high temperature storage characteristics and the safety were examined under the following conditions using the comparative batteries X1 to X9, the results are shown in Table 1 and Table 2 above.
・ Cycle characteristics
  The battery was charged and discharged for 500 cycles under the condition that after a charge current of 500 mA was charged to a charge end voltage of 4.2 V, a discharge current of 500 mA was discharged to a discharge end voltage of 3.1 V. Then, the initial discharge capacity, the discharge capacity after 500 cycles, and the capacity remaining rate [discharge capacity after 500 cycles / initial discharge capacity × 100 (%)] were examined.
・ High temperature storage characteristics
  After each battery was stored at 80 ° C. for 96 hours, the amount of gas generated in the battery was examined.
·safety
  A positive electrode active material 5 mg charged to 4.2 V and EC (ethylene carbonate) 2 mg were sealed in a predetermined container and subjected to DSC measurement, and the heat generation start temperature and the heat generation amount were examined.
[0070]
As is clear from Tables 1 and 2 above, comparative batteries X1, X3, X5, and X7 in which other element M is dissolved in lithium cobaltate are compared in which other elements M are not dissolved in lithium cobaltate. Compared with the battery X9, cycle characteristics are improved, and battery characteristics such as low temperature characteristics not shown in Tables 1 and 2 are also improved (in particular, LiCo_xM_yO₂When y is y ≧ 0.00001). However, it is recognized that the comparative batteries X1, X3, X5, and X7 are less safe than the comparative battery X9 because the amount of gas after high-temperature storage is high, the heat generation start temperature is low, and the heat generation amount is large. It is done.
[0071]
  In contrast, other elements M as well as Al were dissolved in lithium cobalt oxide.Reference batteries A1 to A5, invention batteries A6 to A20Then, it has substantially the same cycle characteristics as the comparative battery X9, and also has a smaller amount of gas after high-temperature storage, a higher heat generation start temperature, and a smaller amount of heat generation than the comparative batteries X1, X3, X5, and X7. Therefore, it is recognized that safety is improved (in particular, LiCo_xM_yAl_zO₂Z is z ≧ 0.0001).
[0072]
  From the results of Experiment 1 and Experiment 2 above, LiCo_xM_yAl_zO₂X, y, z in the range of 0.90 ≦ x <1, 0 <y ≦ 0.05, 0 <z ≦ 0.05, storage at high temperature while suppressing deterioration of positive electrode capacity and cycle characteristics The amount of gas such as time can be reduced and safety can be improved. In particular, the effects described above are further exhibited when the ranges are 0.94 ≦ x <1, 0.00001 ≦ y ≦ 0.05, and 0.0001 ≦ z ≦ 0.05.
[Experiment 3]
  Using the present invention battery A121 and the comparative battery X110, the charge capacity per unit weight in the positive electrode active material was examined, and using the present invention battery A21 and the comparative battery X10, cycle characteristics, high temperature storage characteristics, and safety. The results are shown in Table 3 below. In addition, conditions in cycle characteristics, high temperature storage characteristics and safety are the same conditions as in Experiment 2 above, and in Table 2,Reference batteries A3 and A103, the battery of the present inventionThe results of A8, A108, A13, A113, A18, A118 and comparative batteries X1, X101, X3, X103, X5, X105, X7, X107 are also shown.
[0073]
[Table 3]
  As is apparent from Table 3, the comparative batteries X1, X3, and X10 in which another element M (Ti, Nb, or Zr) is dissolved in lithium cobaltate are mixed with other elements M (Pb or Zn) in lithium cobaltate. ), The cycle characteristics are improved, and battery characteristics such as low-temperature characteristics not shown in Table 3 are also improved. On the other hand, the comparative batteries X1, X3, and X10 have a higher amount of gas after high-temperature storage than the comparative batteries X5 and X7, and have a low heat generation start temperature and a large amount of heat generation, so that the safety is lowered. Is recognized.
[0074]
  On the other hand, not only other elements M (Ti, Nb, or Zr) but also Al was dissolved in lithium cobalt oxide.Reference battery A3, battery of the present inventionA8 and A21 have substantially the same cycle characteristics as those of the comparative batteries X1, X3, and X10, and the amount of gas after high-temperature storage is significantly smaller than that of the comparative batteries X1, X3, and X10. It is recognized that the safety is drastically improved since the heat generation amount is extremely high and the calorific value is extremely small. Therefore, LiCo_xM_yO₂The effect of improving the safety by reducing the amount of gas after high-temperature storage by dissolving other elements M in a solid solution is significant when Ti, Nb, or Zr is used as the other elements M. I understand.
[0075]
                          (Second embodiment)
[Reference Examples 1-5, Example 6~ 21]
  Reference Examples 1-5, Example 6The batteries shown in -20 were produced by the same method as the method shown in the second embodiment. still,Type of M, And LiCo_xM_yAl_zO₂The values of x, y and z in are the same as those in the first embodiment.Reference Examples 1-5, Example 6To 21 (for example, in the second embodimentReference example 1Of the first embodimentReference example 1And the type of M and the values of x, y, and z are the same).
[0076]
  The batteries produced in this way are hereinafter respectivelyReference batteries B1 to B5, Invention battery B6˜B21.
[Comparative Examples 1-9]
  Type of M and LiCo_xM_yAl_zO₂The values of x, y, and z in FIG. 1 correspond to Comparative Examples 1 to 9 in the first example (for example, Comparative Example 1 in the second example is the same as Comparative Example 1 in the first example and types of M and x Other than that, the values of y, z are the same), and the battery was fabricated in the same manner as in Example 1 above.
[0077]
The batteries thus produced are hereinafter referred to as comparative batteries Y1 to Y9, respectively.
[Experiment 1]
Since the cycle characteristics, the high-temperature storage characteristics, and the safety were examined using the batteries B1 to B20 of the present invention and the comparative batteries Y1 to Y9, the results are shown in Tables 4 and 5 below. The cycle characteristics and the high temperature storage characteristics were performed under the same conditions as in Experiment 2 of the first embodiment, and the safety was performed under the following conditions.
·safety
A positive electrode active material 5 mg charged to 4.2 V and a gel polymer electrolyte 2 mg were sealed in a predetermined container and subjected to DSC measurement, and the heat generation start temperature and the heat generation amount were examined.
[0078]
[Table 4]
[0079]
[Table 5]
As is apparent from Tables 4 and 5 above, comparative batteries Y1, Y3, Y5, and Y7 in which other elements M are dissolved in lithium cobaltate are compared in the case where other elements M are not dissolved in lithium cobaltate. Compared with the battery Y9, cycle characteristics are improved, and battery characteristics such as low temperature characteristics not shown in Tables 4 and 5 are also improved (particularly, LiCo_xM_yO₂When y is y ≧ 0.00001). However, it is recognized that the comparative batteries Y1, Y3, Y5, and Y7 are less safe than the comparative battery Y9 because the amount of gas after high temperature storage is high, the heat generation start temperature is low, and the heat generation amount is large. It is done.
[0080]
  In contrast, other elements M as well as Al were dissolved in lithium cobalt oxide.Reference batteries B1 to B5, Invention battery B6-B20 has substantially the same cycle characteristics as the comparative batteries Y1, Y3, Y5, Y7, and has a smaller amount of gas after high temperature storage than the comparative batteries Y1, Y3, Y5, Y7, and further starts to generate heat. It is recognized that the safety is improved because the temperature is high and the calorific value is small (in particular, LiCo_xM_yAl_zO₂Z is z ≧ 0.0001).
[0081]
On the other hand, although not shown in Tables 4 and 5 above, LiCo is a battery that uses a gel polymer electrolyte._xM_yAl_zO₂As the sum of y and z values in (x + y + z = 1) increases (the value of x decreases), it is recognized that the charge capacity per unit weight decreases, and as a result, the weight energy density also decreases. I understood that it would become. Therefore, from the viewpoint of weight energy density, LiCo_xM_yAl_zO₂X, y and z in the formula are 0.9 ≦ x, y ≦ 0.05, z ≦ 0.05 (particularly 0.94 ≦ x, y ≦ 0.05, z ≦ 0.05). It turns out to be desirable.
[0082]
As described above, from the results of Experiment 1, LiCo_xM_yAl_zO₂X, y, z in the range of 0.90 ≦ x <1, 0 <y ≦ 0.05, 0 <z ≦ 0.05, storage at high temperature while suppressing deterioration of positive electrode capacity and cycle characteristics The amount of gas such as time can be reduced and safety can be improved. In particular, the effects described above are further exhibited when the ranges are 0.94 ≦ x <1, 0.00001 ≦ y ≦ 0.05, and 0.0001 ≦ z ≦ 0.05.
[0083]
  In addition, using electrolyteReference batteries A1 to A5, Invention battery A6~ Gel polymer electrolyte was used compared with A21Reference batteries B1 to B5, Invention battery B6~ B21, the amount of gas generated after high-temperature storage is further reduced (for example, using an electrolytic solution)referenceThe battery A1 used 3.8 mg, whereas a gel polymer electrolyte was used.referenceIt is observed that for battery B1 it is 3.0 mg). Therefore, when the present invention is applied to a battery using a gel polymer electrolyte, the effect is further exhibited.
[Experiment 2]
  Since the cycle characteristics, the high temperature storage characteristics and the safety were examined using the battery B21 of the present invention and the comparative battery Y10, the results are shown in Table 6 below. The conditions for cycle characteristics, high-temperature storage characteristics and safety are the same conditions as in Experiment 1 above, and in Table 6,Reference battery B3, Invention battery B8, B13, B18 and the results of the comparative batteries Y1, Y3, Y5, Y7 are also shown.
[0084]
[Table 6]
  As is clear from Table 6, comparative batteries Y1, Y3, and Y10 in which another element M (Ti, Nb, or Zr) is dissolved in lithium cobalt oxide are mixed with other elements M (Pb or Zn) in lithium cobalt oxide. ), The cycle characteristics are improved, and battery characteristics such as low-temperature characteristics not shown in Table 6 are also improved. On the other hand, the comparative batteries Y1, Y3, and Y10 have a larger amount of gas after high-temperature storage than the comparative batteries Y5 and Y7, and the heat generation start temperature is low and the heat generation amount is large. Is recognized.
[0085]
  On the other hand, not only other elements M (Ti, Nb, or Zr) but also Al was dissolved in lithium cobalt oxide.Reference battery B3, Invention battery B8, B21 has substantially the same cycle characteristics as those of the comparative batteries Y1, Y3, Y10, and the amount of gas after high-temperature storage is significantly smaller than that of the comparative batteries Y1, Y3, Y10. It is recognized that the safety is dramatically improved because it is extremely high and the calorific value is extremely small. Therefore, even in a battery using a gel polymer electrolyte, LiCo_xM_yO₂The effect of improving the safety by reducing the amount of gas after high-temperature storage by dissolving other elements M in a solid solution is significant when Ti, Nb, or Zr is used as the other elements M. I understand.
[0086]
【The invention's effect】
As described above, according to the present invention, there is an excellent effect that it is possible to improve safety and reduce the amount of gas generation without deteriorating battery characteristics such as cycle characteristics. In particular, in a battery using an aluminum laminate outer package, since the deformation and rupture of the outer package can be suppressed by reducing the amount of gas generated, the effect is great.
[Brief description of the drawings]
FIG. 1 is a front view of a nonaqueous electrolyte battery according to a first embodiment.
2 is a cross-sectional view taken along line AA in FIG.
FIG. 3 is a cross-sectional view of a laminate outer package used for the nonaqueous electrolyte battery according to the first embodiment.
FIG. 4 is a perspective view of a power generation element used for the nonaqueous electrolyte battery according to the first embodiment.
[Explanation of symbols]
1: Power generation element
2: Storage space
3: Laminated outer package
5: Positive electrode
6: Negative electrode

Claims (5)

In a non-aqueous electrolyte battery in which a positive electrode including a positive electrode active material, a negative electrode, and a non-aqueous electrolyte including a lithium salt are housed in an exterior body,
As the positive electrode active _{material, LiCo x M y Al z O} 2 [M is at least one selected from the group consisting of Nb, Pb, Zn, from Zr, 0.90 ≦ x <1,0 < y ≦ 0. 05, 0 <z ≦ 0.05 , x + y + z = 1]. The LiCo _x M _y Al as _z O ₂ of M, is at least one selected from Nb and Zr, the non-aqueous electrolyte battery according to claim 1, wherein.   The nonaqueous electrolyte battery according to claim 1, wherein the electrolyte is a gel-like solid polymer.   The nonaqueous electrolyte battery according to claim 1, 2 or 3, wherein an exterior body that is deformed by a slight increase in battery internal pressure is used as the exterior body.   The nonaqueous electrolyte battery according to claim 4, wherein an aluminum laminate exterior body is used as the exterior body deformed by the slight increase in battery internal pressure.