JP5669098B2 - Ion conductive crystal and solid electrolyte using the same, battery separator, battery - Google Patents

Description

  The present invention relates to an ion conductive crystal useful for a lithium ion battery, a solid electrolyte using the crystal, a battery separator, and a battery.

  Currently, there are two types of batteries: chemical batteries and physical batteries. A chemical battery is a battery that directly converts energy into direct current through a chemical reaction. The chemical battery includes a primary battery, a secondary battery, a fuel cell, and a biological battery. On the other hand, a physical battery converts energy generated by a physical change caused by light or heat into electrical energy. Physical batteries are classified into solar cells, thermal batteries, nuclear batteries, and the like.

  In recent years, with the rapid market expansion of automobiles, notebook computers, mobile phones and the like, lithium ion batteries have attracted attention as secondary batteries used in these. This lithium-ion battery has excellent features such as light weight, high energy density, high operating voltage, no memory effect, and long charge / discharge cycle life. Is growing.

  In general, a lithium ion battery is composed of a positive electrode, a negative electrode, a separator, and an electrolytic solution. In general, the positive electrode includes a positive electrode active material and a positive electrode current collector, and aluminum is used for the positive electrode current collector. The negative electrode includes a negative electrode active material and a negative electrode current collector, and copper is used for the negative electrode current collector.

  For example, a positive electrode having a positive electrode active material formed on the surface of the positive electrode current collector, a negative electrode having a negative electrode active material formed on the surface of the negative electrode current collector, a separator provided between the positive electrode and the negative electrode, a positive electrode and a negative electrode A lithium ion battery provided with a non-aqueous electrolyte satisfying the above has been disclosed (for example, see Patent Document 1).

  A lithium ion battery using a polymer electrolyte instead of a non-aqueous electrolyte has also been proposed. For example, a lithium ion battery including a separator made of a polymer solid electrolyte membrane formed of polyethylene oxide, polypropylene oxide, or the like between a positive electrode and a negative electrode is disclosed (for example, see Patent Document 2).

JP 2010-123300 A JP 2007-122902 A

  However, in the lithium ion battery described in Patent Document 1, since the separator and the non-aqueous electrolyte are provided between the positive electrode and the negative electrode, the volume of the lithium ion battery becomes large and it is difficult to cope with downsizing. There was a problem of becoming.

  In addition, since an electrolytic solution is used, there is a problem that liquid leakage may occur due to damage or deterioration of the battery body.

  In addition, since the lithium ion battery described in Patent Document 2 uses a polymer electrolyte, not only lithium ions but also electrons are transported between the positive electrode and the negative electrode, resulting in insulation. There was a problem of inferiority.

  Therefore, the present invention has been made in view of the above points, and the object of the present invention is to provide an electrolyte for a lithium ion battery that can cope with downsizing and can prevent leakage of the electrolytic solution. An ion conductive crystal useful as a solid electrolyte, a solid electrolyte using the crystal, a battery separator, and a battery.

In order to achieve the above object, the invention described in claim 1 is formed by ionic bonding between a crown ether having an electrical insulating property and including lithium ions and a minus monovalent dithiolate metal complex. a crown ether 18-crown-6, an ion conductive crystal, characterized by being represented by the following formula (1).

(In the formula, dmit represents 1,3-dithiol-2-thione-4,5-dithiolate, and M represents Ni. ³⁺ , Pd ³⁺ , Au ³⁺ And Pt ³⁺ Any one of the metals is shown. )

Further, an invention according to claim 2, having an electrical insulating property, crown ether inclusion complex lithium ions and a negative monovalent dithiolate metal complex is formed by ionic bonding, the crown ether is 15 It is -crown-5 , and is an ion conductive crystal characterized by being represented by the following formula (2) .

(In the formula, dmit represents 1,3-dithiol-2-thione-4,5-dithiolate, and M represents Ni. ³⁺ , Pd ³⁺ , Au ³⁺ And Pt ³⁺ Any one of the metals is shown. )

The invention according to claim 3 is the ion conductive crystal according to claim 1 or 2 , wherein M is Ni ³⁺ .

The invention according to claim 4 is a solid electrolyte comprising the ion conductive crystal according to any one of claims 1 to 3 .

The invention according to claim 5 is a battery separator comprising the solid electrolyte according to claim 4 .

The invention according to claim 6 includes the positive electrode, the negative electrode, and the solid electrolyte according to claim 4 provided between the positive electrode and the negative electrode and sandwiched between the positive electrode and the negative electrode. It is a battery characterized by the above.

  ADVANTAGE OF THE INVENTION According to this invention, the ion conductive crystal useful as an electrolyte of the lithium ion battery which can respond to size reduction and can prevent the liquid leakage of electrolyte solution can be provided.

It is a figure which shows the coupling | bonding state of the ion conductive crystal which concerns on embodiment of this invention. It is a schematic diagram at the time of using the solid electrolyte which consists of an ion conductive crystal which concerns on embodiment of this invention as a separator of a battery. It is sectional drawing which shows the solid electrolyte which has a function as a positive / negative electrode which comprises the winding electrode body of the lithium ion battery which concerns on embodiment of this invention, electrolyte solution, and a separator. It is a figure which shows the crystal structure of the ion conductive crystal which concerns on embodiment of this invention. It is a figure which shows the crystal structure of the ion conductive crystal which concerns on embodiment of this invention. It is a figure which shows the impedance spectrum of the ion conductive crystal which concerns on embodiment of this invention. It is a figure which shows the impedance spectrum of the ion conductive crystal which concerns on embodiment of this invention. It is a graph which shows the temperature dependence of the magnetic susceptibility of the ion conductive crystal which concerns on embodiment of this invention. It is a figure which shows the result of the differential thermothermal weight simultaneous measurement of the ion conductive crystal which concerns on embodiment of this invention. It is a figure which shows the result of the differential thermothermal weight simultaneous measurement of the ion conductive crystal which concerns on embodiment of this invention.

The ion conductive crystal of the present invention has a structure in which a crown ether (18-crown-6) enclosing a cation (lithium ion) and a dithiolate nickel complex (Ni (dmit) ₂ ) are electrically attracted to each other. It is.

More specifically, the ion conductive crystal of the present invention is a crown ether (Li ⁺ (18-crown-6)) that includes lithium ions that are monovalent cations as a whole and a monovalent anion. A dithiolate nickel complex (Ni (dmit) ₂ ) is formed by being electrically attracted and bound by Coulomb force (that is, by ionic bonding).

  FIG. 1 shows a structural diagram of an ion conductive crystal represented by the formula (3). As shown in FIG. 1, the ion conductive crystal 1 of the present invention is composed of three crown ethers 3, two dithiolate nickel complexes 4, and four water molecules 5 for two lithium ions 2. It is represented by the following chemical formula.

(In the formula, dmit represents 1,3-dithiol-2-thione-4,5-dithiolate.)

  Then, as shown in FIG. 1, three crown ethers 3 are formed as one unit, and these are stacked one-dimensionally, whereby ion channels 9 are formed in the crystal, and are included in the crown ether 3. Lithium ions 2 can move in ion channels 9 made of crown ether 3. Therefore, the crystal represented by the above formula (4) has ionic conductivity.

  In addition, since the dithiolate nickel complex in the ion conductive crystal is in a complete charge transfer state, it is not electrically conductive in a solid state. Accordingly, by using the ion conductive crystal represented by the above formula (4), it is possible to provide a solid electrolyte for a lithium ion battery excellent in insulation that transports only lithium ions and does not transport electrons. Is possible.

  Therefore, the solid electrolyte made of the ion conductive crystal of the present invention is made to function as an electrolyte solution and a separator for a lithium ion battery, and this solid electrolyte 6 is made up of a positive electrode sheet 7 and a negative electrode sheet 8 as shown in FIG. By interposing the solid electrolyte 6 between the positive electrode sheet 7 and the negative electrode sheet 8, the lithium ions 2 can move between the positive electrode sheet 7 and the negative electrode sheet 8 without transporting electrons. It will be possible.

  Therefore, unlike the above-described conventional lithium ion battery, it is not necessary to provide an electrolyte between the positive electrode and the negative electrode, so that the volume of the lithium ion battery can be reduced, and as a result, the battery can be made smaller. It becomes possible to do.

  Further, since it is not necessary to use an electrolytic solution, it is possible to prevent the occurrence of liquid leakage due to damage or deterioration of the battery body.

  The “solid electrolyte” referred to here is a solid that can move ions (here, lithium ions) by an electric field from the outside, and can also extract power by using the movement of ions. Say something that is excellent in insulation.

  In addition, since the dithiolate nickel complex constituting the ion conductive crystal has magnetism (S = 1/2 spin), the ion conductive crystal has magnetism. Therefore, the internal magnetic field in the crystal is changed by an external field (such as a magnetic field), thereby making it possible to control ion conductivity.

  For example, by applying a magnetic field perpendicular to the conduction direction of lithium ions, Lorentz force acts on the lithium ions, thereby inhibiting ion conduction (or promoting ion conduction).

  Next, the outline of the manufacturing method of the ion conductive crystal in this embodiment is shown in the following reaction scheme 1.

<Reaction Scheme 1>
From a crown ether (Li ⁺ (18-crown-6)) that is clathrated with lithium ions, which are monovalent cations as a whole, represented by formula (6), and a dithiolate nickel complex, which is a monovalent anion. In order to obtain the ion conductive crystal, first, a solution in which 18-crown-6 of the formula (5) and lithium perchlorate (LiClO ₄ ) are dissolved in acetonitrile is prepared.

Also, TBA · Ni (dmit) ₂ (bis (1,3-dithiol-2-thione-4,5-dithiolate) nickel (III) tetrabutylammonium) was synthesized, and this TBA · Ni (dmit) ₂ was synthesized. Dissolve in acetonitrile to prepare a solution containing the dithiolate nickel complex. TBA · Ni (dmit) ₂ can be synthesized by a known method (see, for example, Steinmecke, G .; Sieler, HJ; Krimes, R .; Hoyer, E. Phosphorus Sulfur 1979, 7, 49). it can.

  Next, an acetonitrile solution (hereinafter referred to as “solution A”) in which lithium perchlorate and crown ether (18-crown-6) are dissolved is poured into a sample tube, and an acetonitrile solution in which the dithiolate nickel complex is dissolved (hereinafter referred to as “solution A”). Solution B ”) is poured into the sample tube so that solution A and solution B do not mix rapidly.

Next, without covering the sample tube, the lithium ion represented by the formula (6) was included as shown in the above formula (3) by leaving it in the dark at room temperature for 3 to 4 days. Lithium-crown ether (Li ⁺ (18-crown-6)) and a dithiolate nickel complex are electrically attracted to obtain an ion conductive crystal represented by the formula (4).

In addition, the ion conductive crystal of this invention may use 15-crown-5 as a crown ether which clathrates a cation (lithium ion). That is, a lithium ion-crown ether (Li ⁺ (15-crown-5)) which is a monovalent cation as a whole may be used by including lithium ions.

  In this case, the production method of the ion conductive crystal is the same as that in the case of using the above-mentioned 18-crown-6, and the following 18-crown-6 is produced by substituting 15-crown-5. An ion conductive crystal represented by the formula (7) can be obtained.

  Then, by using the ion conductive crystal represented by the formula (7), as in the case of the ion conductive crystal represented by the formula (4), the lithium ion is transported and the electron is not transported. It is possible to provide an electrolyte for a lithium ion battery having excellent properties.

  Of these crown ethers, the use of a crown ether having a large ring size (that is, 18-crown-6) increases the pore size of the crown (that is, the size of the ion channel 9 described above). Lithium ions can easily move in the ion channel made of crown ether, and ion conductivity is improved.

  Next, the lithium ion battery in this embodiment will be described. The shape of the lithium ion battery includes a cylindrical shape and a rectangular shape. In any case, the lithium ion battery is constituted by a wound electrode body (electrode plate group) in which a positive electrode and a negative electrode are wound through a separator. And the structure which inserted this winding electrode body in the battery case and sealed the winding electrode body is employ | adopted.

  FIG. 3 is a cross-sectional view showing a solid electrolyte having a function as a positive and negative electrode, an electrolytic solution, and a separator constituting a wound electrode body of a lithium ion battery according to an embodiment of the present invention.

  As shown in FIG. 3, the wound electrode body 10 includes a positive electrode sheet 7 in which a positive electrode active material 12 is formed on a positive electrode current collector 11, and a negative electrode sheet 8 in which a negative electrode active material 14 is formed on the surface of a negative electrode current collector 13. And a solid electrolyte 6 provided between the positive electrode sheet 7 and the negative electrode sheet 8 and sandwiched between the positive electrode sheet 7 and the negative electrode sheet 8.

  In the present embodiment, the positive electrode sheet 7 and the negative electrode sheet 8 are attached to the solid electrolyte 6 made of an ion conductive crystal that is a single crystal, or the ion conductive crystal is powdered, and the positive electrode sheet 7 and The wound electrode body 10 is formed by being sandwiched by the negative electrode sheet 8 and being thinly pressed.

  Then, the wound electrode body 10 is wound and inserted into the battery case, and the positive electrode lead connected to the positive electrode sheet 7 and the negative electrode lead connected to the negative electrode sheet 8 are provided, thereby constituting the wound electrode body 10. A lithium secondary battery is formed.

  In the present embodiment, the solid electrolyte 6 is formed of the above-described ion conductive crystal. That is, the above-mentioned ion conductive crystal functions as an electrolyte and a separator in a lithium ion battery, and directly contributes to electrode reactions such as a charge reaction and a discharge reaction.

  Hereinafter, the case where the above-described ion conductive crystal is used for the solid electrolyte 6 will be described as an example.

  As the positive electrode current collector 11, for example, aluminum or an alloy containing aluminum as a main component, or one formed of a metal having good conductivity such as titanium is used.

As the positive electrode active material 12, a compound containing lithium (a composite oxide of a transition metal and lithium) can be used. For example, a lithium cobalt-based composite oxide such as LiCoO ₂ or a lithium nickel-based compound such as LiNiO ₂ A complex oxide, a lithium manganese complex oxide such as LiMnO ₂ or the like is used. The positive electrode active material 12 may be used alone or in combination of two or more.

  As the negative electrode current collector 13, for example, one formed of a metal having good conductivity such as copper, nickel, silver or the like is used.

  Examples of the negative electrode active material 14 include graphite materials such as natural graphite, artificial graphite, and high crystal graphite, carbon materials such as petroleum coke, carbon fiber, and fired organic polymer, metal compounds, metal oxides, lithium metal compounds, A lithium-metal composite oxide or the like can be used. The negative electrode active material 14 may be used alone or in combination of two or more.

  Further, the positive electrode active material 12 and the negative electrode active material 14 may contain a conductive agent, a binder, a filler, a dispersant, an ionic conductive agent, and other various additives.

The positive electrode sheet 7 is, for example, added to and mixed with a positive electrode active material 12 such as LiCoO ₂ and a conductive agent such as acetylene black and carbon black, and a binder such as polyvinyl alcohol and polyvinylidene fluoride. It can be formed by pressure forming or dispersing in a solvent to prepare a paste, applying the paste onto the positive electrode current collector 11 made of aluminum foil or the like, and drying.

  The negative electrode sheet 8 is a paste in which the above-mentioned binder is added to and mixed with the negative electrode active material 14 made of, for example, natural graphite, artificial graphite or the like, and this is pressure-molded or dispersed in a solvent. The paste can be formed on a negative electrode current collector 13 such as a copper foil and dried.

Further, the solid electrolyte 6 is obtained by the above-described method, for example, crown ether (Li ⁺ (18-crown-6)) that includes lithium ions that are monovalent cations as a whole and dithio that is a monovalent anion. After producing an ion conductive crystal composed of a rate nickel complex, a single crystal of the ion conductive crystal is used as it is, or the crystal is made into a powder and sandwiched between the positive electrode sheet 7 and the negative electrode sheet 8 to be thinly consolidated. Can be formed.

  As shown in FIGS. 2 and 3, the solid electrolyte 6 is interposed between the positive electrode sheet 7 and the negative electrode sheet 8, and the solid electrolyte 6 is sandwiched between the positive electrode sheet 7 and the negative electrode sheet 8. Thus, the lithium ions 2 can move between the positive electrode sheet 7 and the negative electrode sheet 8.

  In addition, you may change the said embodiment as follows.

In the above embodiment, a dithiolate nickel complex (Ni (dmit) ₂ ) is used as the dithiolate metal complex, but the dithiolate metal complex is not limited to this, and may be an anion for keeping the charge neutral. . That is, in the ion conductive crystal of the present invention, it is the lithium-crown ether moiety that directly contributes to the ion conduction. For example, a configuration using a dithiolate palladium complex (Pd (dmit) ₂ ) or a dithiolate platinum complex (Pt (dmit) ₂ ) may be used.

  In this case, as in the case of using the above-mentioned dithiolate nickel complex, ion conductivity useful for an electrolyte of a lithium ion battery that can cope with downsizing and can prevent leakage of the electrolytic solution. Crystals can be provided.

  In the above embodiment, the wound electrode body 10 having a sheet shape has been described as an example. However, the shape of the wound electrode body 10 is not particularly limited.

  Hereinafter, the present invention will be described based on examples. In addition, this invention is not limited to these Examples, These Examples can be changed and changed based on the meaning of this invention, and they are excluded from the scope of the present invention. is not.

(Synthesis of ion-conductive crystals)
18-crown-6 (trade name 18-crown-6-Ether, manufactured by Tokyo Chemical Industry Co., Ltd.) of formula (5) and lithium perchlorate (anhydrous) (trade name, Lithium perchlorate, manufactured by Kanto Chemical Co., Inc.) , anhydrous) and 10 mg in acetonitrile (Nacalai Tesque) 5 ml,
Solution A was obtained.

Further, TBA · Ni (dmit) ₂ is synthesized by a known method, and then this TBA · Ni (dmit) ₂ is synthesized.
7 mg of Ni (dmit) ₂ was dissolved in 5 ml of acetonitrile (manufactured by Nacalai Tesque) to obtain a solution B containing a dithiolate nickel complex.

  Next, after pouring 5 ml of solution A into the 10 ml sample tube, 5 ml of solution B is added to the sample tube so that solution A and solution B do not mix rapidly (so as not to disturb the interface of solution A). I poured it slowly.

  Next, the sample tube into which the solution A and the solution B were poured was not covered, and was allowed to stand in the dark at room temperature for 3 to 4 days. Then, a black (dark green) plate-like crystal was precipitated at the bottom of the sample tube, and an ion conductive crystal represented by the formula (4) was obtained.

Also, 15-crown-5 (Tokyo Chemical Industry Co., Ltd., trade name 15-crown-5-Ether) 100 mg and lithium perchlorate (anhydrous) (Kanto Chemical Co., Ltd., trade name Lithium perchlorate, anhydrous) 10 mg was dissolved in 5 ml of acetonitrile (manufactured by Nacalai Tesque) to obtain a solution C.

  Then, after pouring 5 ml of solution C into the 10 ml sample tube, 5 ml of solution B is added to the sample tube so that solution C and solution B do not mix rapidly (so as not to disturb the interface of solution C). I poured it slowly.

  Next, the sample tube into which the solution C and the solution B were poured was not covered, and was allowed to stand in the dark at room temperature for 3 to 4 days. Then, a black (dark green) plate-like crystal was precipitated at the bottom of the sample tube, and an ion conductive crystal represented by the formula (7) was obtained.

(Single crystal X-ray analysis)
Next, a single crystal X-ray analysis of the obtained plate crystal is performed, and the plate crystal is an ion conductive crystal represented by the formula (4) and an ion conductive crystal represented by the formula (7). It was confirmed.

Single crystal X-ray analysis was performed by using a measuring device (Bruker, CCD APEX) and using Mo Kα 0.71Å. The crystal structure of the ion-conductive crystal represented by the obtained formula (4) is shown in FIG.

  The unit cell parameters of the obtained ion conductive crystal are shown below.

Unit cell dimensions: a = 11.4822 Å, b = 12.8414 Å, c = 13.8207 ＝, V = 1906.18 ^{３ 3} , α = 82.596 °, β = 88.053 °, γ = 70.614 °
Crystal structure: R ₁ = 0.0417, wR ₂ = 0.1160, GOF = 1.002

  Further, FIG. 5 shows the crystal structure of the obtained ion conductive crystal represented by the formula (7).

  The unit cell parameters of the obtained ion conductive crystal are shown below.

Unit cell dimensions: a = 10.4783Å, b = 12.5798Å, c = 13.1637Å, V = 1693.55Å ³ , α = 84.735 °, β = 78.647 °, γ = 87.558 °
Crystal structure: R ₁ = 0.0419, wR ₂ = 0.1164, GOF = 1.034

  As described with reference to FIG. 1 above, from FIGS. 4 and 5, in the ion conductive crystal represented by the formulas (4) and (7), three crown ethers are used as one unit, which is one-dimensional. As a result, the ion channel is formed in the crystal, and the lithium ions included in the crown ether can move in the ion channel made of crown ether. .

(AC resistance measurement)
Next, the AC resistance of the ion conductive crystal was measured, and it was confirmed that the crystal represented by the above formulas (4) and (7) had ion conductivity.

  In addition, alternating current resistance was performed by using a measuring apparatus (Agilent Technologies company make, E4980A Precision LCR Meter).

  In the measurement, first, two gold wires are stretched on a plate-like crystal obtained by the above synthesis using a gold paste (two-terminal method), and a single crystal is formed on a substrate on which the terminal and the copper wire are connected. The copper wire and the gold wire were connected with a gold paste. Next, using the measuring device, the frequency range was set to 20 Hz to 2 MHz, and the real part (Z ′) and imaginary part (Z ″) of the impedance at room temperature were measured.

  In the measurement of the ion conductive crystal represented by the formula (4), a plate crystal having a length of 0.25 mm, a width of 0.3 mm, and a thickness of 9 μm was used. Moreover, about the ion conductive crystal represented by Formula (7), the plate-shaped crystal | crystallization of length 0.3mm, width 0.3mm, and thickness 9micrometer was used.

  FIG. 6 shows the impedance spectrum of the ion conductive crystal represented by the formula (4), and FIG. 7 shows the impedance spectrum of the ion conductive crystal represented by the formula (7). 6 and 7, the vertical axis represents the imaginary part and the horizontal axis represents the real part.

  As shown in FIGS. 6 and 7, it was found that the impedance spectrum of the ion conductive crystal is a semicircle on the complex plane, and corresponds to the impedance spectrum of the parallel circuit composed of resistance and capacitance.

Further, as shown in FIG. 6, fitting was performed on the high frequency side (6 KHz to 2 MHz) according to a semicircular equation (Y = {r ² − (X−r) ² } ^1/2 ). The conductivity S obtained based on this value was 2.4 × 10 ⁻⁷ S · cm ⁻¹ (S = 1 / Ω).

Further, as shown in FIG. 7, fitting was performed on the high frequency side (1.6 KHz to 2 MHz) according to a semicircular equation (Y = {r ² − (X−r) ² } ^1/2 ). The conductivity S obtained based on this value was 4.2 × 10 ⁻⁸ S · cm ⁻¹ (S = 1 / Ω).

  As mentioned above, it turns out that the crystal | crystallization represented by the said Formula (4) and Formula (7) has ion conductivity.

(Magnetic susceptibility measurement)
Next, the magnetic susceptibility of the ion conductive crystal represented by the formula (4) was measured. The magnetic susceptibility is measured using a SQUID magnetometer (manufactured by QUANTUM DESIGN, QUANTUM DESIGN MPMS5S SQUID) as a measuring device. This was done by fixing and inserting into a SQUID magnetometer.

As shown in FIG. 8, it was suggested that strong antiferromagnetic interaction exists in the obtained crystal. Further, the magnetic susceptibility curve is expressed by a single-triplet thermal excitation model (C = 0.39) represented by the following mathematical formula.
4emu · K / mol), the magnetic exchange interaction | 2J / k _B | / K
= 650K.

(Differential heat measurement)
Next, the thermal characteristics of the ion conductive crystal represented by the formula (4) were measured. In addition, the differential thermothermal weight simultaneous measuring apparatus (The product made by Rigaku, Thermo plus TG8120) was used as a measuring apparatus.

In addition, 10 mg of ion conductive crystals were placed on an aluminum container (diameter 5 mm, height 3 mm), heated in a nitrogen atmosphere from 13 ° C. to 80 ° C. at a heating rate of 2 ° C./min, 80 After leaving it to stand at 5 ° C. for 5 hours, it was further heated to 200 ° C. at a heating rate of 2 ° C./min. The above results are shown in FIGS. The “TG curve” shown in FIG. 9 is a record of the change in weight of the sample with respect to the temperature due to the increase (or decrease) in the ambient temperature. The “DTA curve” shown in FIG. The temperature difference between the reference and the sample is detected and recorded by the electromotive force of the thermocouple provided in the.

As shown in FIG. 9, the weight of the ion conductive crystal gradually decreased from 50 ° C., and a weight change of −3.8% was confirmed at 80 ° C. This substantially coincides with the calculated value (4.0%) of the weight percentage of water molecules contained in the ion conductive crystal, so that the water molecules in the ion conductive crystal gradually escape from around 50 ° C. At ℃, it is considered to be completely absent.

  Further, as shown in FIG. 9, it can be seen that the weight is greatly reduced from around 160.degree. This is considered that the dissolution of the ion conductive crystal itself has started. This can also be seen from the fact that a large peak appears around 160 ° C. as shown in FIG. That is, it is considered that the ionic conductivity of the ion conductive crystal is greatly increased at a temperature of 80 ° C. or more in which water molecules are completely removed, and the ion conductive crystal itself is dissolved at 160 ° C. From this, it is considered that when the ion conductive crystal is applied to a battery, a “meltdown effect” is exhibited in which the function of the battery is stopped with the occurrence of abnormal heat generation.

  In addition, it is thought that the thermal characteristic of the ion conductive crystal represented by Formula (7) can also obtain the same peak as the case of the ion conductive crystal represented by Formula (4). Further, when measuring the thermal characteristics of the ion conductive crystal represented by the formula (7), when the heating rate is 2 ° C./min, the mass reduction rate at 80 ° C. is 2%. preferable. This numerical value of 2% corresponds to a calculated value (2.0%) of the weight percentage of water molecules contained in the ion conductive crystal represented by the formula (7). Also in this case, an improvement in ion conductivity from around 80 ° C. can be expected due to the elimination of water molecules around 80 ° C.

  Examples of utilization of the present invention include ion conductive crystals useful for lithium ion batteries, battery separators using the same, and batteries.

DESCRIPTION OF SYMBOLS 1 Ion conductive crystal 2 Lithium ion 3 Crown ether 4 Dithiolate nickel complex 5 Water molecule 6 Solid electrolyte 7 Positive electrode sheet 8 Negative electrode sheet 9 Ion channel 10 Winding electrode body 11 Positive electrode current collector 12 Positive electrode active material 13 Negative electrode current collector 14 Negative electrode active material

Claims (6)

It is formed by ionic bonding between a crown ether having electrical insulation and inclusion of lithium ions and a minus monovalent dithiolate metal complex, and the crown ether is 18-crown-6, and the following formula (1 An ion conductive crystal characterized by being represented by:
(In the formula, dmit represents 1,3-dithiol-2-thione-4,5-dithiolate, and M represents a metal selected from Ni ³⁺ , Pd ³⁺ , Au ^3+, and Pt ³⁺ . ) It is formed by ionic bonding between a crown ether having electrical insulation and inclusion of lithium ions and a minus monovalent dithiolate metal complex, and the crown ether is 15-crown-5, and the following formula (2 ion conductive crystal, wherein Rukoto represented by).
(In the formula, dmit represents 1,3-dithiol-2-thione-4,5-dithiolate, and M represents a metal selected from Ni ³⁺ , Pd ³⁺ , Au ^3+, and Pt ³⁺ . ) Wherein M is ion conductive crystal according to claim 1 or claim 2, characterized in that a Ni ^3+. A solid electrolyte comprising the ion conductive crystal according to any one of claims 1 to 3 . A battery separator comprising the solid electrolyte according to claim 4 . A battery comprising: a positive electrode; a negative electrode; and the solid electrolyte according to claim 4 provided between the positive electrode and the negative electrode and sandwiched between the positive electrode and the negative electrode.