JP6497013B2 - Lithium ion secondary battery - Google Patents

Description

  The present disclosure relates to a lithium ion secondary battery.

A lithium ion secondary battery using lithium as an electrode reactant in charge and discharge reactions and utilizing its storage and release is highly expected because a large energy density can be obtained as compared with lead batteries and nickel cadmium batteries. In lithium ion secondary batteries, lithium transition metal oxides such as LiCoO ₂ , LiMn ₂ O ₄ and LiFePO ₄ are often used as a positive electrode active material, and LiCu _{1 + x} PO _{4 and the} like are also proposed. The lithium transition metal oxide is generally used in the crystalline phase, and after forming the lithium transition metal oxide, a crystalline phase is formed by performing post annealing or the like. However, since there are various problems such as the need for high temperature treatment for the formation of the lithium transition metal oxide having a crystalline phase, the applicant has a positive electrode which functions in an amorphous state and has high ion conductivity. The solid electrolyte battery using an active material and the said positive electrode active material is proposed in Unexamined-Japanese-Patent No. 2012-256581.

JP 2012-256581

  By the way, there is a strong demand for a lithium ion secondary battery using an organic electrolytic solution (non-aqueous electrolytic solution) which has a large capacity and is excellent in charge and discharge cycles. However, the above patent publication does not mention any lithium ion secondary battery using an organic electrolytic solution (non-aqueous electrolytic solution).

  Therefore, an object of the present disclosure is to provide a lithium ion secondary battery using an organic electrolytic solution (non-aqueous electrolytic solution) which has a large capacity and is excellent in charge and discharge cycles.

A lithium ion secondary battery according to a first aspect to a fourth aspect of the present disclosure for achieving the above object comprises:
Equipped with a positive electrode active material and an organic electrolyte,
The positive electrode active material comprises an amorphous lithium phosphate compound containing lithium (Li), phosphorus (P), element M ¹ and oxygen (O),
The element M ¹ is an element selected from the group consisting of nickel (Ni), cobalt (Co), manganese (Mn), gold (Au), silver (Ag) and palladium (Pd).

And in the lithium ion secondary battery according to the first aspect of the present disclosure, substantially no lithium oxide (Li ₂ O) is present on the surface of the positive electrode active material.

Further, in the lithium ion secondary battery according to the second aspect of the present disclosure, lithium carbonate (Li ₂ CO ₃ ) is present on the surface of the positive electrode active material.

Furthermore, in the lithium ion secondary battery according to the third aspect of the present disclosure,
The organic electrolyte contains a solvent and an electrolyte salt,
The electrolyte salt consists of lithium perchlorate (LiClO ₄ ).

  Moreover, in the lithium ion secondary battery according to the fourth aspect of the present disclosure, the positive electrode active material is coated with lithium nitride phosphate (LiPON).

  In the lithium ion secondary battery according to the first aspect of the present disclosure, substantially no lithium oxide exists on the surface of the positive electrode active material, and in the lithium ion secondary battery according to the second aspect of the present disclosure Lithium carbonate is present on the surface of the positive electrode active material, and in the lithium ion secondary battery according to the third aspect of the present disclosure, the organic electrolyte contains a solvent and an electrolyte salt, and the electrolyte salt is lithium perchlorate In the lithium ion secondary battery according to the fourth aspect of the present disclosure, the positive electrode active material is coated with lithium nitride phosphate. And the lithium phosphoric acid compound which comprises a positive electrode active material has high ion conductivity in an amorphous state. Therefore, it is possible to provide a lithium ion secondary battery which has a large capacity and is excellent in charge and discharge cycles. The effects described in the present specification are merely examples and are not limited, and may have additional effects.

FIGS. 1A and 1B are conceptual diagrams of a positive electrode, a separator, a negative electrode and the like which constitute the lithium ion secondary battery of Example 1 and Example 3, respectively. FIGS. 2A and 2B are graphs showing charge and discharge results in the coin-type lithium ion secondary battery of Example 1 and Example 3 respectively. FIG. 3 is a schematic cross-sectional view showing a configuration of a cylindrical lithium ion secondary battery of Example 4. FIGS. 4A, 4B, 4C, and 4D respectively illustrate a schematic partial cross-sectional view in which a part of the spirally wound electrode body illustrated in FIG. 3 is enlarged, and a first embodiment regarding the arrangement of insulating materials. A schematic sectional view for the purpose, a schematic partial sectional view for explaining the second embodiment concerning the arrangement of the insulating material, and a schematic illustration for explaining the third embodiment concerning the arrangement of the insulating material FIG. FIG. 5 is a schematic exploded perspective view of a laminate film type lithium ion secondary battery of Example 5. FIG. 6 is a schematic cross-sectional view of the wound electrode body shown in FIG. 5 along arrow A-A. FIG. 7 is a schematic exploded perspective view of an application example (battery pack: single cell) of the lithium ion secondary battery of the present disclosure in the sixth embodiment. 8A is a block diagram showing a configuration of an application example (battery pack: single cell) of the lithium ion secondary battery of the present disclosure in Example 6 shown in FIG. 7, and FIG. 8B is a block diagram of the present disclosure in Example 6. It is a block diagram showing the composition of the example of application of a lithium ion secondary battery (battery pack: group battery). 9A, 9B and 9C are block diagrams showing the configuration of an application example (electric vehicle) of a lithium ion secondary battery of the present disclosure in Example 6, and the lithium ion secondary battery of the present disclosure in Example 6, respectively. FIG. 24 is a block diagram showing the configuration of an application example (power storage system) of the present invention, and a block diagram showing the configuration of an application example (power tool) of the lithium ion secondary battery of the present disclosure in Example 6.

Hereinafter, the present disclosure will be described based on examples with reference to the drawings, but the present disclosure is not limited to the examples, and various numerical values and materials in the examples are examples. The description will be made in the following order.
1. Description of the lithium ion secondary battery according to the first to fourth aspects of the present disclosure, in general. Example 1 (lithium ion secondary battery according to first to third aspects of the present disclosure)
3. Example 2 (Modification of Example 1)
4. Example 3 (lithium ion secondary battery according to the fourth aspect of the present disclosure)
5. Fourth Embodiment (Modification of the First to Third Embodiments)
6. Example 5 (another modification of Examples 1 to 3)
7. Example 6 (application example of lithium ion secondary battery of the present disclosure)
8. Other

<General Description of Lithium Ion Secondary Battery According to First to Fourth Aspects of the Present Disclosure>
In the lithium ion secondary battery according to the first aspect of the present disclosure, lithium carbonate (Li ₂ CO ₃ ) is preferably present on the surface of the positive electrode active material.

In the lithium ion secondary battery according to the first aspect of the present disclosure including the above preferred embodiment, or in the lithium ion secondary battery according to the second aspect of the present disclosure, the organic electrolytic solution contains a solvent and an electrolyte salt The electrolyte salt can be in the form of lithium perchlorate (LiClO ₄ ). And, in this case, or in the lithium ion secondary battery according to the third aspect of the present disclosure, the solvent may be a form comprising a carbonate solvent, and the solvent may be ethylene carbonate (EC) and And / or may be in the form of diethyl carbonate (DMC). Alternatively, as a solvent, cyclic carbonates such as propylene carbonate (PC) and butylene carbonate (BC); linear carbonates such as dimethyl carbonate (DMC) and ethyl methyl carbonate (EMC); tetrahydrofuran (THF), 2-methyltetrahydrofuran Cyclic ethers such as 2-MeTHF), 1,3 dioxolane (DOL), 4-methyl-1,3 dioxolane (4-MeDOL), and so on; 1,2 dimethoxyethane (DME), 1,2 diethoxyethane (DEE) Linear ethers; cyclic esters such as γ-butyrolactone (GBL) and γ-valerolactone (GVL); methyl acetate, ethyl acetate, propyl acetate, methyl formate, ethyl formate, propyl formate, methyl butyrate, methyl propionate, propion Chain esters such as ethyl and propyl propionate; tetrahydropyran, 1,3 dioxane, 1,4 dioxane, N, N-dimethylformamide (DMF), N, N-dimethylacetamide (DMA), N-methyl pyrrolidinone (NMP) N-methyloxazolidinone (NMO), N, N'-dimethylimidazolidinone (DMI), dimethyl sulfoxide (DMSO), trimethyl phosphate (TMP), nitromethane (NM), nitroethane (NE), sulfolane (SL), acetonitrile (AN), glutaronitrile (GLN), adiponitrile (ADN), methoxyacetonitrile (MAN), 3-methoxypropionitrile (MPN), diethyl ether; ionic liquids can be mentioned.

Furthermore, in the lithium ion secondary battery according to the first to third aspects of the present disclosure including the preferred embodiments described above, the positive electrode active material is coated with lithium nitride phosphate (LiPON, Li ₃ PO ₄ ) It can be in the form of

  Furthermore, in the lithium ion secondary batteries according to the first to fourth aspects of the present disclosure including the preferred embodiments described above, charging may be performed at 4.0 volts or more.

In the lithium ion secondary battery according to the first aspect of the present disclosure, as described above, substantially no lithium oxide (Li ₂ O) is present on the surface of the positive electrode active material. Here, the phrase "substantially free of lithium oxide" refers to an oxygen atom derived from Li ₂ O (specifically, O 1s by measurement based on X-ray Photoelectron Spectroscopy). ) Is not detected, more specifically, the detection peak value of the oxygen atom derived from Li ₂ O (specifically, O1s) is the detection of the oxygen atom derived from the carbonic acid component (specifically, O1s) It means that the intensity is smaller than the peak value and not detected as a peak. Specifically, the lithium ion secondary battery is disassembled in a glove box, the positive electrode and the negative electrode are separately collected, washed with DMC, and then dried. Then, the electrode after drying is carried into an X-ray photoelectron spectroscopy (XPS) measurement apparatus. Keep the atmosphere unexposed (argon gas atmosphere) until analysis. In the case of surface analysis (not exposed to the atmosphere) by the XPS method, measurement is performed under the following conditions. Then, when the measured Li ₂ O from oxygen atoms (O1s) by XPS method, when the oxygen atom is not detected, and "not present substantial lithium oxide".

<XPS measurement conditions>
XPS device: PHI Quantum 2000
X-ray source: Al-Kα (monochromated), 15 kV-40 W
Analysis diameter: 200 μm

In addition, the presence of lithium carbonate (Li ₂ CO ₃ ) on the surface of the positive electrode active material means that oxygen atoms derived from Li ₂ CO ₃ (specifically, O1s) are detected by measurement based on X-ray photoelectron spectroscopy. It means to be done. More specifically, when the oxygen atom (O1s) derived from Li ₂ CO ₃ is measured by the XPS method based on the method described above, the measured value of this oxygen atom is present as a peak around 532 eV or 532 eV indicating carbonic acid origin "When lithium carbonate is present on the surface of the positive electrode active material".

  The positive electrode active material and lithium nitride phosphate coating the positive electrode active material can be formed into a film based on, for example, a sputtering method, but is not limited to such a method, and others, for example, a coating method, a vapor phase method , Liquid phase method, thermal spraying method, and firing method (sintering method). The application method is a method of mixing particles (powder) of a positive electrode active material with a positive electrode binder and the like, then dispersing the mixture in a solvent such as an organic solvent and applying the mixture to a positive electrode current collector. The vapor phase method includes PVD methods (physical vapor phase growth method) such as vacuum evaporation method, sputtering method, ion plating method, laser ablation method, and various CVD methods (chemical vapor phase growth method) including plasma CVD method. It is. As a liquid phase method, an electrolytic plating method and an electroless plating method can be mentioned. The thermal spraying method is a method of spraying a molten or semi-molten positive electrode active material onto a positive electrode current collector. The firing method is, for example, a method in which a mixture dispersed in a solvent is applied to a positive electrode current collector using a coating method, and then heat treatment is performed at a temperature higher than the melting point of a positive electrode binder or the like. The reaction baking method and the hot press baking method can be mentioned. Alternatively, sol-gel method, SPE (solid phase epitaxy) method, LB (Langmuir Blojet) method can also be mentioned.

In the lithium ion secondary batteries according to the first to fourth aspects of the present disclosure including the preferred embodiments described above, the following substances can also be used as the positive electrode active material, in addition to the above-mentioned substances. That is, the positive electrode active material, further, may be configured of lithium phosphate compound in an amorphous state containing an element M ^2. Further, the cathode active material containing such a configuration, further, may be configured of lithium phosphate compound in an amorphous state containing an additive element M ^3. Here, the element M ² is at least selected from the group consisting of nickel (Ni), cobalt (Co), manganese (Mn), gold (Au), silver (Ag), palladium (Pd) and copper (Cu). It is one kind of element, and the additive element M ³ is B, Mg, Al, Si, Ti, V, Cr, Fe, Zn, Ga, Ge, Nb, Mo, In, Sn, Sb, Te, W, Os Or at least one element selected from the group consisting of Bi, Gd, Tb, Dy, Hf, Ta and Zr.

  For example, when the positive electrode active material is made of an amorphous lithium phosphate compound containing Li, P, Ni, Cu, and O, charge and discharge cycle characteristics can be further improved. In addition, for example, when the positive electrode active material is made of an amorphous lithium phosphate compound containing Li, P, Ni, Pd, and O, it is possible to further increase the capacity and to improve the charge-discharge cycle characteristics. It can be further improved. Furthermore, for example, when the positive electrode active material is composed of an amorphous lithium phosphate compound containing Li, P, Ni, Au, and O, the charge and discharge cycle characteristics can be further improved.

Additive element M ³ are, this only be contained in the lithium phosphate compound, such a lithium phosphate compound can not be used as a positive electrode active material. On the other hand, when the added element M ³ was contained in at least a lithium phosphate compound together with the element M _1, it can function lithium phosphate compound as the positive electrode active material, moreover, depending on the element species of the selection to be added, the positive electrode The characteristics of the active material can be improved, and the capacity can be increased, the cycle characteristics can be improved, and the internal impedance can be reduced, and an excellent high-rate discharge characteristic can be obtained. As the internal impedance is lowered, the potential change at the time of high speed discharge is reduced, and a lithium ion secondary battery with higher potential can be realized. Furthermore, since the ratio of discharge energy to charge energy (discharge energy / charge energy) approaches 1 due to low internal impedance, energy loss decreases, energy efficiency increases, and charge and discharge occur. Heat generation can be suppressed because Joule heat decreases.

Alternatively, the positive electrode active material may contain an amorphous lithium phosphate compound, and the lithium phosphate compound may be a lithium phosphate compound represented by Formula (1) or Formula (2).
Li _X Ni _Y PO _Z (1)
Here, 0 <X <8, preferably 1 ≦ X <8, 2 ≦ Y ≦ 10, and Z is a ratio in which oxygen is stably contained according to the composition ratio of Ni and P.
Li _X Cu _Y PO ₄ (2)
Here, 0.5 ≦ X <7.0, preferably 5.0 <X <7.0, and 1 ≦ Y ≦ 4, preferably 2.2 ≦ Y ≦ 4.

  In the formula (1), the range of the composition ratio X of lithium is preferably 0 <X <8 as described above. The upper limit of the composition ratio X of lithium is defined by the limit at which the potential is maintained. In the confirmed range, the value of the composition ratio X of lithium is preferably less than 8. Further, in the formula (1), the range of the composition ratio Y of Ni is preferably 2 ≦ Y ≦ 10 as described above, from the viewpoint of obtaining sufficient charge and discharge capacity.

The various lithium phosphate compounds described above have the following excellent characteristics as a positive electrode active material. That is, it has a high potential with respect to the pair Li ⁺ / Li. In addition, the flatness of the potential is excellent. That is, the potential fluctuation associated with the composition change is small. In addition, since the composition ratio of lithium is large, the capacity is high. Furthermore, it has high electrical conductivity. In addition, unlike crystalline positive electrode active materials, there is no collapse of the crystal structure due to repeated charge and discharge, etc., and volumetric expansion and contraction due to insertion and desorption of Li can be mitigated, and structural change can be suppressed. Therefore, the charge and discharge cycle characteristics are excellent. In addition, since it can be formed without annealing, the process can be simplified, the yield can be improved, and the resin substrate can be used. And since it can contain Li in a wide range like the positive electrode active material of said Formula (1) or Formula (2), for example, high capacity-ization is possible. For example, in Formula (1), the value of lithium composition ratio X can contain lithium to less than 8 and, in Formula (2), the value of lithium composition ratio X can contain lithium to less than 7 .

  In a positive electrode of a lithium ion secondary battery, a positive electrode active material layer is formed on one side or both sides of a positive electrode current collector. In the negative electrode, for example, a negative electrode active material layer is formed on one side or both sides of the negative electrode current collector. Materials constituting the positive electrode current collector and the negative electrode current collector include copper (Cu), magnesium (Mg), titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), zinc (Zn), Aluminum (Al), germanium (Ge), indium (In), gold (Au), platinum (Pt), silver (Ag), palladium (Pd), etc. or an alloy containing any of these, stainless steel, etc. Can be illustrated.

  The positive electrode active material layer made of the positive electrode active material is a completely amorphous single-phase thin film without containing a crystalline phase. The fact that the positive electrode active material layer is an amorphous single phase can be confirmed by observing a cross section with a transmission electron microscope (TEM). That is, when the cross section of this positive electrode active material layer is observed with a transmission electron microscope, it is possible to confirm the state in which no crystal grain exists in the TEM image. Moreover, it can also confirm based on an electron beam diffraction image and an X-ray-diffraction method (XRD method).

  The negative electrode active material layer contains, as a negative electrode active material, a negative electrode material capable of inserting and extracting lithium. The negative electrode active material layer may further contain a negative electrode binder, a negative electrode conductive agent, and the like. The negative electrode will be described in detail later. The surface of the negative electrode current collector is preferably roughened from the viewpoint of improving the adhesion of the negative electrode active material layer to the negative electrode current collector based on the so-called anchor effect. In this case, at least the surface of the region of the negative electrode current collector where the negative electrode active material layer is to be formed may be roughened. As a method of roughening, for example, a method of forming fine particles using electrolytic treatment can be mentioned. The electrolytic treatment is a method of forming irregularities on the surface of the negative electrode current collector by forming fine particles on the surface of the negative electrode current collector using an electrolytic method in an electrolytic cell.

  The negative electrode active material layer can be formed, for example, based on a coating method, a vapor phase method, a liquid phase method, a thermal spraying method, and a firing method (sintering method). The coating method is a method of mixing particles (powder) of the negative electrode active material with a negative electrode binder and the like, dispersing the mixture in a solvent such as an organic solvent, and applying the mixture to a negative electrode current collector. The vapor phase method includes PVD methods (physical vapor phase growth method) such as vacuum evaporation method, sputtering method, ion plating method, laser ablation method, and various CVD methods (chemical vapor phase growth method) including plasma CVD method. It is. As a liquid phase method, an electrolytic plating method and an electroless plating method can be mentioned. The thermal spraying method is a method of spraying a molten or semi-molten negative electrode active material onto a negative electrode current collector. The firing method is, for example, a method in which a mixture dispersed in a solvent is applied to a negative electrode current collector using a coating method, and then heat treatment is performed at a temperature higher than the melting point of the negative electrode binder etc. The reaction baking method and the hot press baking method can be mentioned.

  In order to prevent lithium from unintentionally depositing on the negative electrode during charging, the chargeable capacity of the negative electrode material is preferably larger than the discharge capacity of the positive electrode. That is, the electrochemical equivalent of the negative electrode material capable of inserting and extracting lithium is preferably larger than the electrochemical equivalent of the positive electrode. The lithium deposited on the negative electrode is, for example, lithium metal when the electrode reactant is lithium.

  Alternatively, the negative electrode can be composed of a lithium foil, a lithium sheet, or a lithium plate.

  The separator separates the positive electrode and the negative electrode, and allows lithium ions to pass while preventing a short circuit of current caused by the contact of the positive electrode and the negative electrode. The separator is, for example, a porous film made of a synthetic resin such as polytetrafluoroethylene, polyolefin resin (polypropylene or polyethylene), aromatic polyamide; porous film such as ceramic; glass fiber; liquid crystal polyester fiber or aromatic polyamide fiber, It is comprised from the nonwoven fabric which consists of cellulosic fiber. Alternatively, the separator may be formed of a laminated film in which two or more types of porous films are laminated, or may be a separator coated with an inorganic material layer or an inorganic material-containing separator.

As a mode of a lithium ion secondary battery, it includes a positive electrode current collector having an inorganic insulating film formed on a substrate and a positive electrode active material layer formed on the inorganic insulating film, and an organic electrolytic solution (non-aqueous electrolytic solution) The structure where the negative electrode collector in which the separator and the negative electrode active material layer were formed was laminated can be mentioned. As a substrate in such a structure, for example, polycarbonate (PC) resin substrate, fluorine resin substrate, polyethylene terephthalate (PET) substrate, polybutylene terephthalate (PBT) substrate, polyimide (PI) substrate, polyamide (PA) substrate, polysulfone PSF) substrates, polyethersulfone (PES) substrates, polyphenylene sulfide (PPS) substrates, polyetheretherketone (PEEK) substrates, polyethylene naphthalate (PEN), cycloolefin polymers (COP) can be mentioned. Further, the material forming the inorganic insulating film may be a material having a low hygroscopic property and capable of forming an insulating film having moisture resistance. Examples of such materials include Si, Cr, Zr, Al, Ta, An oxide or nitride of Ti, Mn, Mg, Zn, or a simple substance of a sulfide or a mixture thereof can be mentioned. More specifically, Si ₃ N ₄ , SiO ₂ , Cr ₂ O ₃ , ZrO ₂ , ZrO ₂ , Al ₂ O ₃ , Ta ₂ O ₅ , TiO ₂ , Mn ₂ O ₃ , MgO, ZnS, etc., or a mixture thereof Can be mentioned.

  Examples of the shape and form of the lithium ion secondary battery include coin type, button type, flat type, square type, cylindrical type, and laminate type (laminated film type).

  Example 1 relates to a lithium ion secondary battery according to the first to third aspects of the present disclosure. A conceptual diagram of the positive electrode, the separator, the negative electrode, etc. constituting the lithium ion secondary battery of Example 1 is shown in FIG. 1A.

The lithium ion secondary battery of Example 1 includes a positive electrode 1, a separator 3 including an organic electrolytic solution (non-aqueous electrolytic solution) 4 (shown by black spots in FIGS. 1A and 1B), and a negative electrode 2. The positive electrode 1 is composed of a positive electrode current collector 1A and a positive electrode active material layer 1B. Specifically, in the positive electrode 1, the positive electrode active material constituting the positive electrode active material layer 1B is made of lithium, phosphorus, lithium phosphate compound in an amorphous state containing an element M ¹ and oxygen, the element M ¹ is nickel , One element selected from the group consisting of cobalt, manganese, gold, silver and palladium.

More specifically, in Example 1, the positive electrode active material was composed of Li _5.7 Ni _3.9 PO _12.1 (M ¹ : Ni) in an amorphous state. Specifically, a positive electrode active material layer 1B having a thickness of 0.2 μm is formed on one side (a surface facing the negative electrode 2) of a positive electrode current collector 1A made of a gold foil having a thickness of 20 μm based on a sputtering method. . Moreover, the negative electrode 2 is comprised from the lithium board of thickness 1 mm. Furthermore, the separator 3 is composed of a 20 μm thick microporous polyethylene film. The film forming conditions based on the sputtering method of the positive electrode active material layer 1B are illustrated in Table 1 below.

[Table 1]
Positive electrode active material: Li _5.7 Ni _3.9 PO _12.1 (M ¹ : Ni)
Target composition: Co-sputtered target size of Li ₂ CO ₃ / Li ₃ PO ₄ mixed sintered body and Ni: 4 inch diameter sputtering gas: Ar gas / O ₂ gas = 80/20 (volume ratio)
20 sccm, 0.2 Pa
Sputtering power: mixed sintered body ... 600 watts (RF)
Ni ... 200 watts (DC)
Film thickness: 0.2 μm

The organic electrolyte contains a solvent and an electrolyte salt (supporting salt), and the electrolyte salt consists of lithium perchlorate (LiClO ₄ ). Here, the solvent comprises a carbonate solvent, specifically ethylene carbonate (EC) and diethyl carbonate (DMC). The composition of the organic electrolytic solution is as shown in Table 2 below. A lithium ion secondary battery manufactured using lithium hexafluorophosphate (LiPF ₆ ) as an electrolyte salt instead of lithium perchlorate was used as Comparative Example 1.

[Table 2]
Example 1
Electrolyte salt (supporting salt): lithium perchlorate 1 mole / solvent 1 kg
Solvent: EC / DMC = 3/7 (mass ratio)
Comparative Example 1
Electrolyte salt (supporting salt): lithium hexafluorophosphate 1 mol / solvent 1 kg
Solvent: EC / DMC = 3/7 (mass ratio)

From the positive electrode 1, the negative electrode 2, and the separator 3 including the organic electrolyte solution (non-aqueous electrolyte solution) 4 described above, a lithium ion secondary battery having a known structure and structure was assembled by a known method. The lithium ion secondary batteries in Examples 1 to 3 and Comparative Example 1 are all coin type. Then, a charge and discharge test was performed. The charge was CC / CV type, charge current 10 microamperes, charge voltage 4.8 volts, charge current density 0.0057 milliamperes / cm ² , termination condition 8 microamperes or 20 hours. Moreover, discharge was made into CC system and it was set as discharge condition 10 microampere. That is, charging was performed at 4.0 volts or more (specifically, 4.8 volts).

  The charge and discharge results are shown in FIG. 2A. The horizontal axis in FIG. 2A is the number of times of charge and discharge, and the vertical axis is a value obtained by normalizing the capacity (cycle maintenance rate). That is, it is the value (%) of the discharge capacity in the Nth charge and discharge cycle when the discharge capacity in the first charge and discharge cycle after performing the initial charge and discharge is assumed to be 100%. In FIG. 2A, “A” indicates the result of Example 1, and “B” indicates the result of Comparative Example 1. The lithium ion secondary battery of Example 1 shows good cycle characteristics. On the other hand, in Comparative Example 1, an increase in resistance was recognized as the number of cycles increased, and the capacity decreased significantly as the number of cycles increased.

  After five cycle tests, the lithium ion secondary battery was disassembled and analysis based on XPS was performed. The analysis results (peak counts of peaks) of the O1s binding energy are as shown in Table 3 below.

[Table 3]
Example 1 Comparative Example 1
Oxygen atom derived from Li ₂ O 258 2947
Oxygen atom derived from Li ₂ CO ₃ 5004 4516
Peak intensity ratio 0.05 0.65

From Table 3, in the lithium ion secondary battery of Example 1 showing excellent cycle characteristics, substantially no lithium oxide exists on the surface of the positive electrode active material, and carbonic acid on the surface of the positive electrode active material It can be seen that lithium is present. On the other hand, in the lithium ion secondary battery of Comparative Example 1 in which the cycle characteristics are inferior, while lithium oxide is present on the surface of the positive electrode active material, lithium carbonate present on the surface of the positive electrode active material is more than that of Example 1. There were also few. In addition, the value of the peak intensity ratio which is (oxygen atom derived from Li ₂ O) / (oxygen atom derived from Li ₂ CO ₃ ) is clearly smaller in Example 1 than in Comparative Example 1, and hence In No. 1, it can be seen that Li ₂ CO ₃ is apparently more abundant than Li ₂ O on the surface of the positive electrode active material. That is, in Example 1, since lithium oxide was not substantially present, an increase in resistance could be suppressed, a result that the decrease in discharge potential was small and the cycle retention rate was high was obtained.

  Further, from the XRD analysis of the positive electrode active material layer, a clear peak was not obtained, and it was confirmed that the positive electrode active material layer was in an amorphous state. Furthermore, when the positive electrode active material layer was observed with a transmission electron microscope, crystal grains were not confirmed in the TEM image, and a halo ring showing amorphous was observed in the electron diffraction image. This also confirms that the positive electrode active material layer is amorphous.

  As described above, in the lithium ion secondary battery of Example 1, or in the lithium ion secondary battery of Example 2 described below, substantially no lithium oxide exists on the surface of the positive electrode active material, Lithium carbonate is present on the surface of the positive electrode active material, the organic electrolytic solution contains a solvent and an electrolyte salt, and the electrolyte salt is composed of lithium perchlorate, so the lithium has a large capacity and is excellent in charge and discharge cycles. An ion secondary battery can be provided.

The second embodiment is a modification of the first embodiment. In Example 2, the positive electrode active material was constituted of Li _6.5 Mn _3.2 PO _12.1 (M ¹ : Mn) instead of Li _5.7 Ni _3.9 PO _{12.1 in} the amorphous state. Except for this point, a lithium ion secondary battery similar to that of Example 1 was manufactured, and a cycle test and an XPS analysis similar to those of Example 1 were performed. In Example 2, the cycle maintenance rate after 5 cycles was 80%. The sputtering conditions are shown in Table 4 below.

[Table 4]
Positive electrode active material: Li _6.5 Mn _3.2 PO _12.1 (M ¹ : Mn)
Target composition: Co-sputtered target size of Li ₃ PO ₄ sintered body and Mn: 4-inch diameter sputtering gas: Ar gas / O ₂ gas = 80/20 (volume ratio)
20 sccm, 0.2 Pa
Sputtering power: Sintered body ··· 600 watts (RF)
Mn ··· 200 watts (DC)
Film thickness: 0.32 μm

Example 3 relates to a lithium ion secondary battery according to the fourth aspect of the present disclosure. The conceptual diagram of the positive electrode 1, the separator 3, the negative electrode 2 etc. which comprise the lithium ion secondary battery of Example 3 is shown to FIG. 1B. In the lithium ion secondary battery of Example 3, the positive electrode active material is coated with lithium nitride phosphate (LiPON, Li ₃ PO ₄ ). That is, the positive electrode active material layer 1B is covered with the lithium nitride phosphate layer 1C. Except for this point, the configuration and structure of the lithium ion secondary battery of Example 3 can be the same as the configuration and structure of the lithium ion secondary battery of Examples 1 and 2, so detailed description will be given. I omit it.

  Specifically, in the same manner as in Example 1, a positive electrode active material layer 1B having a thickness of 0.2 μm is formed on one surface (a surface facing the negative electrode 2) of a positive electrode current collector 1A made of gold foil having a thickness of 20 μm. After forming based on the sputtering method, a 0.02 μm thick lithium nitride phosphate film 1C was formed based on the sputtering method on the positive electrode active material layer 1B. The film formation conditions based on the sputtering method of the lithium nitride phosphate film 1C are illustrated in Table 5 below.

[Table 5]
Target composition: Li ₃ PO ₄
Target size: Diameter 4 inches Sputtering gas: Ar gas / N ₂ gas = 50/50 (volume ratio)
40 sccm, 0.2 Pa
Sputtering power: 600 watts (RF)

  In FIG. 2B, the results of measuring the cycle maintenance rate of the lithium ion secondary battery of Example 3 (see “A” in FIG. 2B) and the results of measuring the cycle maintenance rate in the lithium ion secondary battery of Example 1 (See "B" in FIG. 2B). The cycle retention rate is remarkably improved by coating the positive electrode active material (positive electrode active material layer 1B) with lithium nitride phosphate (lithium nitride phosphate layer 1C). It is understood that

A lithium ion secondary battery was prepared as Example 3A in which the electrolyte salt (supporting salt) was changed from lithium perchlorate (LiClO ₄ ) to lithium hexafluorophosphate (LiPF ₆ ), and the cycle retention rate was measured. As a result, the cycle maintenance rate at the fifth time was 55%. On the other hand, the cycle maintenance rate in the fifth time of Comparative Example 1 was 42%. That is, even when lithium hexafluorophosphate is used as the electrolyte salt (supporting salt), the cycle maintenance rate can be improved by coating the positive electrode active material with lithium nitride phosphate.

As described above, in Example 3, a lithium ion secondary battery excellent in charge and discharge cycles can be provided by covering the positive electrode active material with lithium nitride phosphate (LiPON, Li ₃ PO ₄ ). it can.

  The fourth embodiment is a modification of the first to third embodiments. The lithium ion secondary battery of Example 4 comprises a cylindrical lithium ion secondary battery. A schematic cross-sectional view of the lithium ion secondary battery of Example 4 is shown in FIG. 3, and a schematic enlarged partial cross-sectional view of the spirally wound electrode body 20 is shown in FIG. 4A.

  In the lithium ion secondary battery of Example 4, the spirally wound electrode body 20 and the pair of insulating plates 12 and 13 are accommodated in the substantially hollow cylindrical battery can 11. The wound electrode body 20 can be produced, for example, by laminating the positive electrode 21 and the negative electrode 22 with the separator 23 interposed therebetween to obtain a laminate, and then winding the laminate.

  The battery can 11 has a hollow structure in which one end is closed and the other end is opened, and made of iron <Fe>, aluminum <Al>, or the like. The surface of the battery can 11 may be plated with nickel <Ni> or the like. The pair of insulating plates 12 and 13 sandwich the wound electrode body 20 and is disposed so as to extend perpendicularly to the winding circumferential surface of the wound electrode body 20. A battery cover 14, a safety valve mechanism 15, and a thermal resistance element (PTC element) 16 are crimped to the open end of the battery can 11 via a gasket 17, whereby the battery can 11 is sealed. The battery cover 14 is made of, for example, the same material as the battery can 11. The safety valve mechanism 15 and the thermal resistance element 16 are provided inside the battery cover 14, and the safety valve mechanism 15 is electrically connected to the battery cover 14 via the thermal resistance element 16. In the safety valve mechanism 15, the disc plate 15A is reversed when the internal pressure becomes equal to or more than a certain level due to internal short circuit or external heating. And thereby, the electrical connection of the battery cover 14 and the winding electrode body 20 is cut | disconnected. In order to prevent abnormal heat generation caused by a large current, the resistance of the heat sensitive resistance element 16 increases as the temperature rises. The gasket 17 is made of, for example, an insulating material. Asphalt etc. may be applied to the surface of the gasket 17.

  A center pin 24 is inserted at the winding center of the winding electrode body 20. However, the center pin 24 may not be inserted at the winding center. A positive electrode lead 25 made of a conductive material such as aluminum is connected to the positive electrode 21. A negative electrode lead 26 made of a conductive material such as nickel is connected to the negative electrode 22. The positive electrode lead 25 is welded to the safety valve mechanism 15 and electrically connected to the battery lid 14. The negative electrode lead 26 is welded to the battery can 11 and electrically connected to the battery can 11.

  Based on the method described in Examples 1 to 3, the positive electrode 21 is manufactured by forming the positive electrode active material layer on both sides of the positive electrode current collector.

When producing the negative electrode 22, first, 97 parts by weight of a negative electrode active material (graphite) and 3 parts by weight of a negative electrode binder are mixed to obtain a negative electrode mixture. The average particle diameter d ₅₀ of artificial graphite is set to 20 μm. In addition, as the negative electrode binder, for example, a mixture of 1.5 parts by mass of an acryl-modified styrene-butadiene copolymer and 1.5 parts by mass of carboxymethylcellulose is used. Then, the negative electrode mixture is mixed with water to form a paste-like negative electrode mixture slurry. Thereafter, a negative electrode mixture slurry is applied on both sides of a strip-shaped negative electrode current collector 22A (copper foil with a thickness of 15 μm) using a coating apparatus, and then the negative electrode mixture slurry is dried to form a negative electrode active material layer 22B. Do. Then, the negative electrode active material layer 22B is compression molded using a roll press.

  The separator 23 is made of a microporous polyethylene film with a thickness of 20 μm. The wound electrode body 20 is impregnated with the organic electrolytic solution (non-aqueous electrolytic solution) described in Examples 1 to 3.

  An insulating material may be provided in any of the regions (regions between active materials) between the positive electrode active material contained in the positive electrode 21 and the negative electrode active material contained in the negative electrode 22. The place where the insulating material is disposed is not particularly limited as long as it is any of the regions between the active materials. That is, the insulating material may be present in the positive electrode 21 (positive electrode active material layer 21B) or may be present in the negative electrode 22 (negative electrode active material layer 22B), and the positive electrode 21 and the negative electrode 22 And may exist between As an example, with regard to the place where the insulating material is disposed, for example, three aspects can be mentioned as described below.

  In the first embodiment, as shown in FIG. 4B, the positive electrode active material layer 21B contains a particulate positive electrode active material 211. Then, on the surface of the positive electrode active material 211, a layer containing an insulating material (the active material insulating layer 212 which is a first insulating layer) is formed. The active material insulating layer 212 may cover only a part of the surface of the positive electrode active material 211 or may cover the entire surface. When the active material insulating layer 212 covers a part of the surface of the positive electrode active material 211, a plurality of active material insulating layers 212 separated from each other may be present. The active material insulating layer 212 may be a single layer or a multilayer.

The active material insulating layer 212 is made of an inorganic insulating material such as insulating ceramic, or alternatively, is made of an organic insulating material such as an insulating polymer compound, or alternatively is made of an inorganic insulating material and an organic insulating material. . Specifically, aluminum oxide <Al ₂ O ₃ >, silicon oxide <SiO ₂ >, magnesium oxide <MgO>, titanium oxide <TiO ₂ >, zirconium oxide <ZrO ₂ > may be exemplified as the insulating ceramic. LiNbO ₃ , LIPON <Li _{3 + y} PO _4-x N _x , where 0.5 ≦ x ≦ 1, −0.3 <y <0.3>, LISICON (Lithium-Super-Ion-Conductor A material called Thio-LISICON (for example, Li _3.25 Ge _0.25 P _0.75 S ₄ ), Li ₂ S, Li ₂ S-P ₂ S ₅ , Li ₂ S-SiS ₂ , Li ₂ S-GeS ₂ , Li _{2 S-B 2 S 5, Li} 2 S-Al 2 S 5 and _{Li 2 O-Al 2 O 3} -TiO 2 -P 2 O 5 (LATP) may be exemplified. The insulating polymer compound may be the same as the material constituting the positive electrode binder or the negative electrode binder, but among them, homopolymers of vinylidene fluoride (for example, polyvinylidene fluoride) or copolymers For example, a copolymer of vinylidene fluoride and hexafluoropropylene) is preferred. It is because it is excellent in physical strength and electrochemically stable. The monomer copolymerized with vinylidene fluoride may be a monomer other than hexafluoropropylene.

  In the second embodiment, as shown in FIG. 4C, a layer containing an insulating material (a negative electrode insulating layer 213 which is a second insulating layer) is provided on the surface of the negative electrode 22 (negative electrode active material layer 22B). The details of the covering state, layer structure, constituent materials, and the like of the negative electrode insulating layer 213 are the same as those of the above-described active material insulating layer 212. Further, in this case, in particular, when the negative electrode insulating layer 213 contains the insulating polymer compound, the adhesion of the separator 23 to the negative electrode 22 is improved, so that the wound electrode body 20 is hardly distorted. And thereby, while the decomposition reaction of an organic electrolyte solution is suppressed, the leak of the organic electrolyte solution with which the separator 23 is impregnated is also suppressed. Therefore, resistance does not easily rise even if charge and discharge are repeated, and the lithium ion secondary battery becomes difficult to swell.

  In the third embodiment, as shown in FIG. 4D, a layer containing an insulating material (a separator insulating layer 214 which is a third insulating layer) is provided on the surface of the separator 23. The separator insulating layer 214 may be provided on the surface of the separator 23 facing the positive electrode 21, may be provided on the surface facing the negative electrode 22, or may be provided on both surfaces. The details of the covering state, the layer structure, the constituent materials, and the like of the separator insulating layer 214 are the same as those of the above-described active material insulating layer 212. In this case, in particular, when the separator insulating layer 214 contains the insulating polymer compound, the adhesion of the separator 23 to the positive electrode 21 and the negative electrode 22 is improved, so the above-mentioned negative electrode insulating layer 213 is made of the polymer compound. The same advantages are obtained as in the case of including.

  By disposing the insulating material in any of the regions between the active materials, it is possible to achieve both battery characteristics and safety. That is, when the insulating material is disposed in the region between the active materials, abnormality such as thermal runaway does not easily occur inside the lithium ion secondary battery, and the safety is improved.

  The lithium ion secondary battery of Example 4 operates, for example, as follows. That is, when lithium ions are released from the positive electrode 21 during charging, the lithium ions are occluded by the negative electrode 22 through the organic electrolytic solution. On the other hand, when lithium ions are released from the negative electrode 22 at the time of discharge, the lithium ions are occluded by the positive electrode 21 through the organic electrolytic solution. The lithium ion secondary battery has, for example, an open circuit voltage (battery voltage) at full charge of 4.2 to 6.0 volts, preferably 4.25 to 6.0 volts, more preferably 4.3 volts. It is desirable to be designed to be ~ 4.55 volts. In this case, the amount of lithium released per unit mass is large even when using the same type of positive electrode active material as compared with the case where the open circuit voltage at full charge is 4.2 volts. Become. Thus, the amount of the positive electrode active material and the amount of the negative electrode active material are adjusted, and the lithium ion secondary battery is designed such that the open circuit voltage (battery voltage) at the time of full charge becomes a predetermined voltage (upper limit voltage). By doing so, high energy density can be obtained.

  The procedure for forming the active material insulating layer 212 on the surface of the positive electrode active material 211 is, for example, as follows. That is, the insulating ceramic may be deposited on the surface of the positive electrode active material 211 based on a PVD method such as a sputtering method or a CVD method. Alternatively, a sol-gel method may be used, and in this case, after the positive electrode active material 211 is immersed in an alkoxide solution containing aluminum, silicon or the like to deposit a precursor layer on the surface of the positive electrode active material 211 And the precursor layer may be fired.

  When the negative electrode 22 is manufactured, the negative electrode active material layer 22B is formed on the negative electrode current collector 22A. Specifically, a negative electrode active material, a negative electrode binder, a negative electrode conductive agent and the like are mixed to form a negative electrode mixture, and then the negative electrode mixture is mixed with an organic solvent or the like to form a paste-like negative electrode mixture Make it a slurry. Then, after applying the negative electrode mixture slurry on both surfaces of the negative electrode current collector 22A, the negative electrode mixture slurry is dried to form the negative electrode active material layer 22B. Next, the negative electrode active material layer 22B is compression molded using a roll press machine or the like. The procedure for forming the negative electrode insulating layer 213 on the surface of the negative electrode active material layer 22B is, for example, as follows. The case where the negative electrode insulating layer 213 contains an insulating ceramic and an insulating polymer compound will be described as an example. When forming the negative electrode insulating layer 213, particles of insulating ceramic, insulating polymer compound, and a solvent such as N-methyl-2-pyrrolidone are mixed to disperse the particles of insulating ceramic in the solvent. And the insulating polymer compound is dissolved in the solvent. Then, after immersing the negative electrode 22 in the mixed solution, the negative electrode 22 is taken out of the mixed solution and dried. As a result, the solvent in the mixed solution evaporates and the insulating polymer compound forms a film, so that the negative electrode insulating layer 213 is formed on the surface of the negative electrode active material layer 22B. In this case, the thickness of the negative electrode insulating layer 213 may be adjusted by pressurizing the negative electrode 22 before drying. Instead of immersing the negative electrode 22 in the mixed solution, the mixed solution may be applied to the surface of the negative electrode active material layer 22B.

Alternatively, when forming the negative electrode insulating layer 213, first, 80 parts by mass of powdered insulating ceramic and 20 parts of insulating polymer compound (polyvinylidene fluoride) are mixed, and then the mixture is dispersed in an organic solvent Let the treatment solution be prepared. Aluminum oxide <Al ₂ O ₃ > and silicon oxide <SiO ₂ > are used as powdered insulating ceramics. The average particle diameter d ₅₀ of the insulating ceramic is 0.5 μm. Then, after immersing the negative electrode 22 in the processing solution, the thickness of the processing solution supplied to the surface of the negative electrode 22 is adjusted using a gravure roller. Then, the treatment solution is dried at 120 ° C. using a drier to evaporate the organic solvent in the treatment solution. Thus, the negative electrode insulating layer 213 can be formed on the surface of the negative electrode active material layer 22B. The thickness of the negative electrode insulating layer 213 is, eg, 5 μm.

  The procedure for forming the separator insulating layer 214 on the surface of the separator 23B is the same as the procedure for forming the negative electrode insulating layer 213 described above. When the separator insulating layer 214 contains only the insulating polymer compound, the same procedure as in the case where the separator insulating layer 214 contains the insulating ceramic and the insulating polymer compound except that particles of the insulating ceramic are not used. Should be used.

  Alternatively, in the case of forming the separator insulating layer 214, first, a processing solution is prepared based on the same procedure as in the case of preparing the negative electrode insulating layer 213. Next, the separator 23 is immersed in the treatment solution. Then, after the separator 23 is pulled out of the processing solution, the separator 23 is washed with water. Then, the treatment solution supplied to the surface of the separator 23 is dried at 80 ° C. with hot air to evaporate the organic solvent in the treatment solution. Thus, the separator insulating layer 214 can be formed on both sides of the separator 23. The thickness (total thickness) of the separator insulating layer 214 formed on both sides of the separator 23 is, eg, 4.5 μm.

  When a lithium ion secondary battery is assembled using the positive electrode 21 and the negative electrode 22, the positive electrode lead 25 is attached to the positive electrode current collector 21 A and the negative electrode lead 26 is attached to the negative electrode current collector 22 A using a welding method. Then, the positive electrode 21 and the negative electrode 22 are stacked via the separator 23, wound, and the wound end portion of the wound body is fixed with an adhesive tape to produce the wound electrode body 20, and then the wound electrode body 20 Insert the center pin 24 at the center of the Next, the wound electrode body 20 is housed inside the battery can 11 while sandwiching the wound electrode body 20 between the pair of insulating plates 12 and 13. In this case, the front end of the positive electrode lead 25 is attached to the safety valve mechanism 15 and the front end of the negative electrode lead 26 is attached to the battery can 11 using a welding method or the like. Thereafter, the organic electrolytic solution is injected into the inside of the battery can 11 based on the pressure reduction method, and the separator 23 is impregnated with the organic electrolytic solution. Next, the battery cover 14, the safety valve mechanism 15 and the thermal resistance element 16 are crimped to the open end of the battery can 11 through the gasket 17.

  The fifth embodiment is also a modification of the first to third embodiments. The lithium ion secondary battery of Example 5 comprises a laminated film type lithium ion secondary battery. The typical disassembled perspective view of the lithium ion secondary battery of Example 5 is shown in FIG. 5, and the typical expanded sectional view along the arrow AA of a winding electrode body is shown in FIG.

  In the lithium ion secondary battery of Example 5, as shown in FIG. 5, a wound electrode body 30 is housed inside a film-shaped exterior member 40. The wound electrode body 30 can be manufactured by winding the laminated body after laminating the positive electrode 33 and the negative electrode 34 via the separator 35 and the electrolyte layer 36. The positive electrode lead 31 is attached to the positive electrode 33, and the negative electrode lead 32 is attached to the negative electrode 34. The outermost periphery of the wound electrode body 30 is protected by a protective tape 37.

  The positive electrode lead 31 and the negative electrode lead 32 project in the same direction from the inside to the outside of the package member 40. The positive electrode lead 31 is formed of a conductive material such as aluminum. The negative electrode lead 32 is formed of a conductive material such as copper, nickel, stainless steel or the like. These conductive materials are, for example, thin plate or mesh.

  The exterior member 40 is a single sheet of film foldable in the direction of the arrow R shown in FIG. 5, and a recess for housing the wound electrode body 30 is provided in a part of the exterior member 40. The exterior member 40 is, for example, a laminate film in which a fusion bonding layer, a metal layer, and a surface protective layer are laminated in this order. In the manufacturing process of the lithium ion secondary battery, after the exterior member 40 is folded so that the fusion layers face each other via the wound electrode body 30, the outer peripheral edge portions of the fusion layers are fused. However, the exterior member 40 may be a laminate of two laminated films with an adhesive or the like. The fusion layer is made of, for example, a film of polyethylene, polypropylene or the like. The metal layer is made of, for example, an aluminum foil or the like. The surface protective layer is made of, for example, nylon, polyethylene terephthalate or the like. Among them, the exterior member 40 is preferably an aluminum laminated film in which a polyethylene film, an aluminum foil, and a nylon film are laminated in this order. However, the exterior member 40 may be a laminate film having another laminated structure, a polymer film such as polypropylene, or a metal film. Specifically, the exterior member 40 is a moisture-resistant aluminum in which a nylon film (thickness 30 μm), an aluminum foil (thickness 40 μm), and a non-oriented polypropylene film (thickness 30 μm) are laminated in this order from the outside. It consists of a laminate film (total thickness 100 μm).

  An adhesive film 41 is inserted between the exterior member 40 and the positive electrode lead 31 and between the exterior member 40 and the negative electrode lead 32 in order to prevent the entry of the outside air. The adhesive film 41 is made of a material having adhesiveness to the positive electrode lead 31 and the negative electrode lead 32, for example, a polyolefin resin or the like, more specifically, polyethylene, polypropylene, modified polyethylene, modified polypropylene or the like.

  As shown in FIG. 6, the positive electrode 33 has a positive electrode active material layer 33B on one side or both sides of a positive electrode current collector 33A. Further, the negative electrode 34 has a negative electrode active material layer 34B on one side or both sides of the negative electrode current collector 34A. The configurations and structures of the positive electrode current collector 33A, the positive electrode active material layer 33B, the negative electrode current collector 34A, the negative electrode active material layer 34B, and the separator 35 are the same as the positive electrode current collector 21A, the positive electrode active material layer 21B, and the negative electrode collector in Example 4. The structure and the structure of the current collector 22A, the negative electrode active material layer 22B, and the separator 23 can be the same.

  Based on the method described in Examples 1 to 3, the positive electrode 21 is manufactured by forming the positive electrode active material layer on both sides of the positive electrode current collector.

When producing the negative electrode 34, first, 97 parts by weight of a negative electrode active material (graphite) and 3 parts by weight of a negative electrode binder (polyvinylidene fluoride) are mixed to obtain a negative electrode mixture. The average particle diameter d ₅₀ of graphite is 20 μm. Next, the negative electrode mixture is mixed with an organic solvent (N-methyl-2-pyrrolidone) to form a paste-like negative electrode mixture slurry. Then, the negative electrode mixture slurry is applied on both sides of the strip-shaped negative electrode current collector 34A (copper foil having a thickness of 15 μm) using a coating apparatus, and then the negative electrode mixture slurry is dried to form the negative electrode active material layer 34B. Do. Then, the negative electrode active material layer 34B is compression molded using a roll press.

Alternatively, the negative electrode active material (silicon) and the precursor of the negative electrode binder (polyamic acid) may be mixed to form a negative electrode mixture. In this case, the mixing ratio is set to silicon: polyamic acid = 80: 20 in dry mass ratio. The average particle diameter d ₅₀ of silicon is 1 μm. N-methyl-2-pyrrolidone and N, N-dimethylacetamide are used as solvents for the polyamic acid. After compression molding, the negative electrode mixture slurry is heated in a vacuum atmosphere under conditions such as 400 ° C. × 12 hours. Thus, polyimide, which is a negative electrode binder, is formed.

  The electrolyte layer 36 contains an organic electrolytic solution and a holding polymer compound, and the organic electrolytic solution is held by the holding polymer compound. The electrolyte layer 36 is a so-called gel electrolyte, and high ion conductivity (for example, 1 mS / cm or more at room temperature) is obtained, and liquid leakage of the organic electrolytic solution is prevented. The electrolyte layer 36 may further contain other materials such as additives.

  Specific examples of the polymer compound for holding include polyacrylonitrile, polyvinylidene fluoride, polytetrafluoroethylene, polyhexafluoropropylene, polyethylene oxide, polypropylene oxide, polyphosphazene, polysiloxane, polyvinyl fluoride, polyvinyl acetate, Polyvinyl alcohol, polymethyl methacrylate, polyacrylic acid, polymethacrylic acid, styrene-butadiene rubber, nitrile-butadiene rubber, polystyrene, and polycarbonate can be exemplified. The holding polymer compound may be a copolymer. As a copolymer, specifically, a copolymer of vinylidene fluoride and hexafluoropyrene can be exemplified. Among them, polyvinylidene fluoride as a homopolymer is preferable from the viewpoint of electrochemical stability. The copolymer of vinylidene fluoride and hexafluoropyrene is preferred as the copolymer.

  The configuration of the organic electrolytic solution is the same as the configuration of the organic electrolytic solution used for the cylindrical lithium ion secondary battery. However, in the electrolyte layer 36 which is a gel electrolyte, the solvent of the organic electrolytic solution is a broad concept including not only liquid materials but also materials having ion conductivity capable of dissociating the electrolyte salt. Therefore, when using a polymer compound having ion conductivity, the polymer compound is also included in the solvent. Instead of the gel electrolyte layer 36, an organic electrolytic solution may be used as it is. In this case, the organic electrolyte solution is impregnated into the wound electrode body 30.

  Specifically, when forming the electrolyte layer 36, first, an organic electrolytic solution is prepared. Then, the organic electrolytic solution, the polymer compound for holding, and the organic solvent (dimethyl carbonate) are mixed to prepare a sol precursor solution. A copolymer of hexafluoropropylene and vinylidene fluoride (the amount of copolymerization of hexafluoropropylene = 6.9% by mass) was used as the polymer compound for holding. Next, after applying a precursor solution to the positive electrode 33 and the negative electrode 34, the precursor solution is dried to form a gel electrolyte layer 36.

  Even in the lithium ion secondary battery of Example 5, as described in Example 4, a region between the positive electrode active material contained in the positive electrode 33 and the negative electrode active material contained in the negative electrode 22. An insulating material may be provided in any of the (region between active materials).

  The lithium ion secondary battery provided with the gel electrolyte layer 36 can be manufactured, for example, based on the following three types of procedures. In the following description, the formation procedure of the insulating layers 212, 213, and 214 is omitted.

  In the first procedure, first, the positive electrode 33 and the negative electrode 34 are manufactured by the same manufacturing procedure as the positive electrode 21 and the negative electrode 22 in the fourth embodiment. That is, the positive electrode active material layer 33B is formed on both surfaces of the positive electrode current collector 33A, and the negative electrode active material layer 34B is formed on both surfaces of the negative electrode current collector 34A. Meanwhile, the organic electrolytic solution, the polymer compound for holding, and the organic solvent are mixed to prepare a sol precursor solution. Then, after applying the precursor solution to the positive electrode 33 and the negative electrode 34, the precursor solution is dried to form a gel electrolyte layer 36. Thereafter, the positive electrode lead 31 is attached to the positive electrode current collector 33A using a welding method or the like, and the negative electrode lead 32 is attached to the negative electrode current collector 34A. Next, the positive electrode 33 and the negative electrode 34 are laminated via a separator 35 made of a microporous propylene film with a thickness of 25 μm, and wound to form a wound electrode body 30, and then a protective tape is formed on the outermost periphery. Paste 37 Thereafter, the package member 40 is folded so as to sandwich the wound electrode body 30, and then the outer peripheral edge portions of the package member 40 are adhered to each other using a heat fusion method or the like. Insert 30. An adhesive film (acid-modified propylene film with a thickness of 50 μm) 41 is inserted between the positive electrode lead 31 and the negative electrode lead 32 and the package member 40.

  Alternatively, in the second procedure, first, the positive electrode 33 and the negative electrode 34 are manufactured by the same manufacturing procedure as the positive electrode 21 and the negative electrode 22 in the fourth embodiment. Then, the positive electrode lead 31 is attached to the positive electrode 33, and the negative electrode lead 32 is attached to the negative electrode 34. Thereafter, the positive electrode 33 and the negative electrode 34 are stacked via the separator 35 and wound to form a wound body which is a precursor of the wound electrode body 30, and then the protective tape 37 is formed on the outermost periphery of the wound body. Paste Next, the package member 40 is folded so as to sandwich the wound body, and the remaining outer peripheral edge excluding the outer peripheral edge of one side of the outer package member 40 is adhered using a heat fusion method or the like, and a bag is formed The wound body is housed inside the exterior member 40 of FIG. On the other hand, the composition for electrolyte is prepared by mixing an organic electrolytic solution, a monomer which is a raw material of a polymer compound, a polymerization initiator and, if necessary, another material such as a polymerization inhibitor. Then, after the composition for electrolyte is injected into the inside of the bag-like exterior member 40, the exterior member 40 is sealed using a heat fusion method or the like. The monomers are then thermally polymerized to form a polymeric compound. Thus, a gel electrolyte layer 36 is formed.

  Alternatively, in the third procedure, a wound body is manufactured and a bag-like exterior member is manufactured in the same manner as in the second procedure except that the separator 35 coated with the polymer compound on both sides is used. Store inside of 40. The polymer compound applied to the separator 35 is, for example, a polymer (homopolymer, copolymer or multicomponent copolymer) containing vinylidene fluoride as a component. Specifically, a binary copolymer comprising polyvinylidene fluoride, vinylidene fluoride and hexafluoropropylene as a component, and a ternary copolymer comprising vinylidene fluoride, hexafluoropropylene and chlorotrifluoroethylene as a component It is union etc. One or more other polymer compounds may be used together with the polymer containing vinylidene fluoride as a component. Thereafter, an organic electrolytic solution is prepared and injected into the inside of the exterior member 40, and then the opening of the exterior member 40 is sealed using a heat fusion method or the like. Next, the package member 40 is heated while applying a load, and the separator 35 is closely attached to the positive electrode 33 and the negative electrode 34 via the polymer compound. As a result, the organic electrolytic solution is impregnated into the polymer compound, and the polymer compound is gelated to form the electrolyte layer 36.

  In the third procedure, blistering of the lithium ion secondary battery is suppressed more than in the first procedure. Also, in the third procedure, compared to the second procedure, the solvent and the monomer that is the raw material of the polymer compound hardly remain in the electrolyte layer 36, so the process of forming the polymer compound is well controlled. Ru. Therefore, the positive electrode 33, the negative electrode 34, and the separator 35 sufficiently adhere to the electrolyte layer 36.

  In the sixth embodiment, an application example of the lithium ion secondary battery of the present disclosure (hereinafter, may be simply referred to as “secondary battery”) will be described.

  The application of the secondary battery of the present disclosure is a machine, device, apparatus, apparatus, system (a plurality of devices, etc.) which can use the secondary battery of the present disclosure as a driving power source or operating power storage source. Is not particularly limited as long as it is a group of The secondary battery used as a power source may be a main power source (a power source used preferentially) or an auxiliary power source (a power source used in place of the main power source or switched from the main power source) It may be. When the secondary battery is used as an auxiliary power supply, the main power supply is not limited to the secondary battery.

  Specifically, as applications of the secondary battery of the present disclosure, video cameras, camcorders, digital still cameras, mobile phones, personal computers, television receivers, various display devices, cordless phones, headphone stereos, music players, portable devices Various electronic devices such as radio, electronic books such as electronic books and electronic newspaper, portable information terminals including PDA (Personal Digital Assistant), electric devices (including portable electronic devices); toys; portable household appliances such as electric shaver Lighting devices such as interior lights; Medical electronic devices such as pacemakers and hearing aids; Storage devices such as memory cards; Battery packs used for personal computers etc. as removable power sources; Electric tools such as electric drills and electric saws; Power storage systems such as household battery systems that store power in preparation for emergencies etc. Systems and home energy servers (home power storage devices); storage units and backup power supplies; electric vehicles such as electric cars, electric bikes, electric bicycles, Segway (registered trademark), etc .; power driving force conversion devices for aircraft and ships (specifically For example, although the drive of a motive power motor can be illustrated, it does not limit to these applications.

  Above all, it is effective that the secondary battery of the present disclosure is applied to a battery pack, an electric vehicle, an electric power storage system, an electric tool, an electronic device, an electric device and the like. Since excellent battery characteristics are required, it is possible to effectively improve the performance by using the secondary battery of the present disclosure. The battery pack is a power source using a secondary battery, and is a so-called assembled battery or the like. The electric vehicle is a vehicle that operates (travels) using a secondary battery as a driving power source, and may be an automobile (hybrid vehicle or the like) provided with a driving source other than the secondary battery. The power storage system is a system using a secondary battery as a power storage source. For example, in a household power storage system, since power is stored in a secondary battery which is a power storage source, home electric appliances and the like can be used using the power. The electric power tool is a tool in which a movable portion (for example, a drill or the like) moves using a secondary battery as a power source for driving. Electronic devices and electric devices are devices that exhibit various functions as a secondary battery as a power supply (power supply source) for operation.

  Hereinafter, some application examples of the secondary battery will be specifically described. The configuration of each application described below is merely an example, and the configuration can be changed as appropriate.

  A schematic perspective view in which a battery pack using single cells is disassembled is shown in FIG. 7, and a block diagram showing the configuration of the battery pack (single cells) is shown in FIG. 8A. The battery pack is a simple battery pack (so-called soft pack) using one secondary battery, and is mounted on, for example, an electronic device represented by a smartphone. The battery pack is provided with a power supply 111 composed of the secondary battery of the laminate film type of Embodiment 5 and a circuit board 116 connected to the power supply 111. The positive electrode lead 112 and the negative electrode lead 113 are attached to the power source 111.

  A pair of adhesive tapes 118 and 119 is attached to both sides of the power supply 111. The circuit board 116 is provided with a protection circuit (PCM: Protection Circuit Module). The circuit board 116 is connected to the positive electrode 112 via the tab 114 and connected to the negative electrode lead 113 via the tab 115. Also, a lead wire with connector 117 for external connection is connected to the circuit board 116. When the circuit board 116 is connected to the power supply 111, the circuit board 116 is protected from above and below by the label 120 and the insulating sheet 121. By attaching the label 120, the circuit board 116 and the insulating sheet 121 are fixed. The circuit board 116 includes a control unit 121, a switch unit 122, a PTC 123, and a temperature detection unit 124. The power supply 111 can be connected to the outside through the positive electrode terminal 125 and the negative electrode terminal 127, and the power supply 111 is charged and discharged through the positive electrode terminal 125 and the negative electrode terminal 127. The temperature detection unit 124 can detect the temperature via a temperature detection terminal (so-called T terminal).

  The control unit 121 that controls the operation of the entire battery pack (including the use state of the power supply 111) includes a central processing unit (CPU), a memory, and the like. When the battery voltage reaches the overcharge detection voltage, the control unit 121 disconnects the switch unit 122 to prevent the charging current from flowing in the current path of the power supply 111. In addition, when a large current flows during charging, the control unit 121 disconnects the switch unit 122 and cuts off the charging current. In addition, when the battery voltage reaches the overdischarge detection voltage, the control unit 121 disconnects the switch unit 122 so that the discharge current does not flow in the current path of the power supply 111. In addition, when a large current flows during discharge, the control unit 121 disconnects the switch unit 122 and cuts off the discharge current.

  The overcharge detection voltage of the secondary battery is, for example, 4.20 volts ± 0.05 volts, and the overdischarge detection voltage is, for example, 2.4 volts ± 0.1 volts.

  The switch unit 122 switches the use state of the power supply 111 (whether the connection between the power supply 111 and the external device can be performed or not) according to an instruction from the control unit 121. The switch unit 122 is provided with a charge control switch, a discharge control switch, and the like. The charge control switch and the discharge control switch are made of, for example, a semiconductor switch such as a field effect transistor (MOSFET) using a metal oxide semiconductor. The charge and discharge current is detected based on, for example, the on resistance of the switch unit 122.

  A temperature detection unit 124 including a temperature detection element 126 such as a thermistor measures the temperature of the power supply 111, and outputs the measurement result to the control unit 121. The measurement result of the temperature detection unit 124 is used for charge / discharge control by the control unit 121 at the time of abnormal heat generation, correction processing at the time of remaining capacity calculation by the control unit 121, and the like.

  The circuit board 116 may not have the PTC 123. In this case, a PTC element may be separately provided on the circuit board 116.

  Next, a block diagram showing the configuration of a battery pack (assembled battery) different from that shown in FIG. 8A is shown in FIG. 8B. The battery pack includes, for example, a control unit 61, a power supply 62, a switch unit 63, a current measurement unit 64, a temperature detection unit 65, a voltage detection unit 66, and a switch control unit in a housing 60 made of plastic material or the like. A memory 68, a temperature detection element 69, a current detection resistor 70, a positive terminal 71, and a negative terminal 72 are provided.

  The control unit 61 controls the operation of the entire battery pack (including the use state of the power supply 62), and includes, for example, a CPU. The power supply 62 is, for example, a battery pack including two or more secondary batteries (not shown) described in the first to fifth embodiments, and the connection form of the secondary batteries may be in series or in parallel. And both mixed types may be used. As one example, the power supply 62 includes six secondary batteries connected in two parallel three series.

  The switch unit 63 switches the use state of the power supply 62 (whether or not the power supply 62 can be connected to an external device) according to an instruction from the control unit 61. The switch unit 63 includes, for example, a charge control switch, a discharge control switch, a charging diode, and a discharging diode (none of which are shown). The charge control switch and the discharge control switch are made of, for example, a semiconductor switch such as a MOSFET.

  The current measuring unit 64 measures the current using the current detection resistor 70, and outputs the measurement result to the control unit 61. The temperature detection unit 65 measures the temperature using the temperature detection element 69, and outputs the measurement result to the control unit 61. The temperature measurement result is used, for example, for charge / discharge control by the control unit 61 at the time of abnormal heat generation, correction processing at the time of remaining capacity calculation by the control unit 61, or the like. The voltage detection unit 66 measures the voltage of the secondary battery in the power supply 62, converts the measured voltage from analog to digital, and supplies the converted voltage to the control unit 61.

  The switch control unit 67 controls the operation of the switch unit 63 in accordance with the signals input from the current measurement unit 64 and the voltage detection unit 66. For example, when the battery voltage reaches the overcharge detection voltage, the switch control unit 67 disconnects the switch unit 63 (charge control switch) and performs control so that the charging current does not flow in the current path of the power supply 62. Thus, the power supply 62 can only discharge via the discharge diode. Also, for example, when a large current flows during charging, the switch control unit 67 cuts off the charging current. Furthermore, for example, when the battery voltage reaches the overdischarge detection voltage, the switch control unit 67 disconnects the switch unit 63 (discharge control switch) so that the discharge current does not flow in the current path of the power supply 62. Do. This allows the power supply 62 to only charge via the charging diode. Further, for example, when a large current flows during discharge, the switch control unit 67 cuts off the discharge current.

  The overcharge detection voltage of the secondary battery is, for example, 4.20 volts ± 0.05 volts, and the overdischarge detection voltage is, for example, 2.4 volts ± 0.1 volts.

  The memory 68 is, for example, an EEPROM or the like which is a non-volatile memory. The memory 68 stores, for example, numerical values calculated by the control unit 61, information of the secondary battery measured in the manufacturing process stage (for example, internal resistance in an initial state), and the like. By storing the full charge capacity of the secondary battery in the memory 68, the control unit 61 can grasp information such as the remaining capacity. The temperature detection element 69 formed of a thermistor or the like measures the temperature of the power supply 62, and outputs the measurement result to the control unit 61. The positive electrode terminal 71 and the negative electrode terminal 72 are terminals connected to an external device (for example, a personal computer) operated by the battery pack, an external device or the like used for charging the battery pack (for example, a charger or the like) . Charging and discharging of the power source 62 are performed via the positive electrode terminal 71 and the negative electrode terminal 72.

  Next, FIG. 9A shows a block diagram showing a configuration of an electric vehicle such as a hybrid vehicle which is an example of the electric vehicle. For example, the electrically powered vehicle includes a control unit 74, an engine 75, a power supply 76, a driving motor 77, a differential gear 78, a generator 79, a transmission 80 and a clutch 81, an inverter 82, inside a metal casing 73. 83 and various sensors 84 are provided. In addition, the electric vehicle includes, for example, a differential gear 78, a front wheel drive shaft 85 connected to the transmission 80, a front wheel 86, a rear wheel drive shaft 87, and a rear wheel 88.

  The electrically powered vehicle can travel, for example, using either the engine 75 or the motor 77 as a drive source. The engine 75 is a main power source, such as a gasoline engine. When the engine 75 is used as a power source, the driving force (rotational force) of the engine 75 is transmitted to the front wheel 86 or the rear wheel 88 via, for example, the differential 78 serving as a driving unit, the transmission 80 and the clutch 81. The rotational power of the engine 75 is also transmitted to the generator 79, and the generator 79 generates AC power using the rotational power, and the AC power is converted to DC power via the inverter 83 and stored in the power supply 76. . On the other hand, when the motor 77 which is a conversion unit is used as a power source, the electric power (DC power) supplied from the power source 76 is converted into AC power via the inverter 82, and the motor 77 is driven using AC power. The driving force (rotational force) converted from the electric power by the motor 77 is transmitted to the front wheel 86 or the rear wheel 88 via, for example, the differential 78 as a driving unit, the transmission 80 and the clutch 81.

  When the electric vehicle decelerates via a braking mechanism (not shown), the resistance during deceleration is transmitted to the motor 77 as a rotational force, and the motor 77 may generate AC power using the rotational force. AC power is converted to DC power via inverter 82, and DC regenerative power is stored in power supply 76.

  The control unit 74 controls the operation of the entire electric vehicle, and includes, for example, a CPU. The power supply 76 includes one or more secondary batteries (not shown) described in the first to fifth embodiments. The power supply 76 may be connected to an external power supply, and may be configured to store power by receiving power supply from the external power supply. The various sensors 84 are used, for example, to control the rotational speed of the engine 75 and to control the opening degree (throttle opening degree) of a throttle valve (not shown). The various sensors 84 include, for example, a speed sensor, an acceleration sensor, an engine speed sensor, and the like.

  Although the case where the electric vehicle is a hybrid vehicle has been described, the electric vehicle may be a vehicle (electric vehicle) that operates using only the power supply 76 and the motor 77 without using the engine 75.

  Next, a block diagram showing the configuration of the power storage system is shown in FIG. 9B. The power storage system includes, for example, a control unit 90, a power supply 91, a smart meter 92, and a power hub 93 inside a house 89 such as a home or a commercial building.

  The power supply 91 is connected to, for example, an electric device (electronic device) 94 installed inside the house 89, and can be connected to an electric vehicle 96 stopped outside the house 89. Further, the power supply 91 is connected to, for example, a private generator 95 installed in a house 89 via a power hub 93, and can be connected to an external centralized power system 97 via a smart meter 92 and the power hub 93. is there. The electrical device (electronic device) 94 includes, for example, one or more home appliances. As a household appliance, a refrigerator, an air-conditioner, a television receiver, a water heater etc. can be mentioned, for example. The private generator 95 is configured of, for example, a solar power generator, a wind power generator, or the like. Examples of the electric vehicle 96 include an electric car, a hybrid car, an electric motorcycle, an electric bicycle, Segway (registered trademark), and the like. As a centralized power system 97, a commercial power source, a power generator, a power transmission network, a smart grid (next generation power transmission network) can be mentioned, and also, for example, a thermal power plant, a nuclear power plant, a hydroelectric power plant, a wind power plant Although various solar cells, fuel cells, wind power generators, micro-hydro power generators, geothermal power generators, etc. can be exemplified as power generators provided in the centralized power system 97. It is not limited to these.

  The control unit 90 controls the operation of the entire power storage system (including the use state of the power supply 91), and includes, for example, a CPU. The power supply 91 includes one or more secondary batteries (not shown) described in the first to fifth embodiments. The smart meter 92 is, for example, a network compatible power meter installed in the house 89 on the power demand side, and can communicate with the power supply side. Then, the smart meter 92 controls the balance of supply and demand in the house 89 while communicating with the outside, for example, to enable efficient and stable energy supply.

  In this power storage system, for example, power is stored in the power supply 91 from the centralized power system 97 which is an external power supply via the smart meter 92 and the power hub 93, and from the private generator 95 which is an independent power supply via the power hub 93. Thus, power is stored in the power supply 91. The electric power stored in the power supply 91 is supplied to the electric device (electronic device) 94 and the electric vehicle 96 according to the instruction of the control unit 90, so that the electric device (electronic device) 94 can be operated and The vehicle 96 can be charged. That is, the power storage system is a system that enables storage and supply of power in the house 89 using the power supply 91.

  The power stored in the power supply 91 is arbitrarily available. Therefore, for example, power can be stored in the power supply 91 from the centralized power system 97 at midnight, at which the electricity charge is inexpensive, and the power accumulated in the power supply 91 can be used during the day when the electricity charge is high.

  The power storage system described above may be installed for each household (one household), or may be installed for each household (plural households).

  Next, a block diagram showing the configuration of the power tool is shown in FIG. 9C. The power tool is, for example, a power drill, and includes a control unit 99 and a power supply 100 inside a tool body 98 made of a plastic material or the like. For example, a drill portion 101 which is a movable portion is rotatably attached to the tool body 98. The control unit 99 controls the operation of the entire power tool (including the use state of the power supply 100), and includes, for example, a CPU. The power supply 100 includes one or more secondary batteries (not shown) described in the first to fifth embodiments. The control unit 99 supplies power from the power supply 100 to the drill unit 101 according to the operation of the operation switch (not shown).

  Although the present disclosure has been described above based on the preferred embodiments, the present disclosure is not limited to these embodiments, and various modifications are possible. For example, although the case where the battery structure is a cylindrical type and a laminate film type and the lithium ion secondary battery has a wound structure or the coin type has been described as an example, the present invention is not limited thereto. The lithium ion secondary battery may have a battery structure such as a button type, a flat type, or a square type, or may have another structure such as a laminated structure.

  When the positive electrode active material was composed of the materials shown in Tables 6, 7 and 8 below, a lithium ion secondary battery having substantially the same performance as that of Examples 1 to 3 could be obtained.

[Table 6]

[Table 7]

[Table 8]

  Hereinafter, the negative electrode etc. which comprise the lithium ion secondary battery mentioned above are explained in full detail.

  Specific examples of the positive electrode binder or the negative electrode binder include styrene-butadiene rubber, fluorine-based rubber, synthetic rubber such as ethylene propylene diene, and polymer materials such as polyvinylidene fluoride and polyimide. In addition, as the conductive agent, for example, carbon materials such as graphite, carbon black, acetylene black and ketjen black can be exemplified. However, if it is a material having conductivity, it may be a metal material, a conductive polymer, etc. You can also.

  As a material which comprises a negative electrode, a carbon material can be mentioned, for example. In the carbon material, a high energy density can be stably obtained because the change in crystal structure at the time of lithium storage and release is very small. In addition, since the carbon material also functions as a negative electrode conductive agent, the conductivity of the negative electrode active material layer is improved. Examples of the carbon material include graphitizable carbon (soft carbon), non-graphitizable carbon (hard carbon), and graphite (graphite). However, the spacing of the (002) plane in non-graphitizable carbon is preferably 0.37 nm or more, and the spacing of the (002) plane in graphite is preferably 0.34 nm or less. More specifically, as carbon materials, for example, pyrolytic carbons; cokes such as pitch coke, needle coke and petroleum coke; glassy carbon fibers; baking polymer compounds such as phenol resin and furan resin at an appropriate temperature Organic polymer compound fired body which can be obtained by carbonization; activated carbon; carbon blacks can be mentioned. In addition, as a carbon material, low crystalline carbon heat-treated at a temperature of about 1000 ° C. or less can also be mentioned, or amorphous carbon can also be used. The shape of the carbon material may be any of fibrous, spherical, granular and scaly.

  Alternatively, as a material constituting the negative electrode, for example, a material containing one or two or more kinds of metal elements and metalloid elements as constituent elements (hereinafter referred to as “metal-based materials”) may be mentioned. It is possible to obtain high energy density. The metal-based material may be any one of a single substance, an alloy, and a compound, or may be a material composed of two or more of them, or a material having at least a part of one or more of these phases. It may be The alloy includes a material containing one or more metal elements and one or more metalloid elements, as well as a material containing two or more metal elements. The alloy may also contain nonmetallic elements. Examples of the structure of the metal-based material include a solid solution, a eutectic (eutectic mixture), an intermetallic compound, and two or more of these coexisting substances.

  Examples of metal elements and metalloid elements include metal elements and metalloid elements capable of forming an alloy with lithium. Specifically, for example, magnesium <Mg>, boron <B>, aluminum <Al>, gallium <Ga>, indium <In>, silicon <Si>, germanium <Ge>, germanium <Ge>, tin <Sn>, lead <Pbビ ス, bismuth <Bi>, cadmium <Cd>, silver <Ag>, zinc <Zn>, hafnium <Hf>, zirconium <Zr>, yttrium <Y>, palladium <Pd>, platinum <Pt> Among them, silicon <Si> and tin <Sn> are preferable from the viewpoint of excellent ability to insert and extract lithium and obtaining extremely high energy density.

  Examples of the material containing silicon as a constituent element include a single substance of silicon, a silicon alloy, and a silicon compound, and a material composed of two or more of these may be used, or one or two or more of these may be used. It may be a material having at least a part of the phase of Examples of the material containing tin as a constituent element include a single substance of tin, a tin alloy, and a tin compound, and a material composed of two or more of these may be used, or one or more of these may be used. It may be a material having at least a part of the phase of The term "single substance" means a single substance in a general sense, and may contain a trace amount of impurities, and does not necessarily mean 100% purity.

As elements other than silicon constituting silicon alloys or silicon compounds, tin <Sn>, nickel <Ni>, copper <Cu>, iron <Fe>, cobalt <Co>, manganese <Mn>, zinc <Zn>, indium <In>, silver <Ag>, titanium <Ti>, germanium <Ge>, bismuth <Bi>, antimony <Sb>, chromium <Cr>, carbon <C>, oxygen <O> It can also be mentioned. As a silicon alloy or a silicon compound, specifically, SiB ₄ , SiB ₆ , Mg ₂ Si, Ni ₂ Si, TiSi ₂ , MoSi ₂ , MoSi ₂ , CoSi ₂ , NiSi ₂ , CaSi ₂ , CrSi ₂ , Cu ₅ Si, FeSi ₂ , MnSi ₂ , NbSi ₂ , TaSi ₂ , VSi ₂ , WSi ₂ , ZnSi ₂ , SiC, Si ₃ N ₄ , Si ₂ N ₂ O, SiO _v (0 <v ≦ 2, preferably 0.2 <v < 1.4) and LiSiO can be exemplified.

As elements other than tin constituting tin alloy or tin compound, silicon <Si>, nickel <Ni>, copper <Cu>, iron <Fe>, cobalt <Co>, manganese <Mn>, zinc <Zn>, indium <In>, silver <Ag>, titanium <Ti>, germanium <Ge>, bismuth <Bi>, antimony <Sb>, chromium <Cr>, carbon <C>, oxygen <O> It can also be mentioned. Specific examples of the tin alloy or tin compound include SnO _w (0 <w ≦ 2), SnSiO ₃ , LiSnO, and Mg ₂ Sn. In particular, the material containing tin as a constituent element is preferably, for example, a material containing a second constituent element and a third constituent element together with tin (first constituent element) (hereinafter referred to as “Sn-containing material”). As the second constituent element, for example, cobalt <Co>, iron <Fe>, magnesium <Mg>, titanium <Ti>, vanadium <V>, chromium <Cr>, manganese <Mn>, nickel <Ni>, copper <Cu>, zinc <Zn>, gallium <Ga>, zirconium <Zr>, niobium <Nb>, molybdenum <Mo>, silver <Ag>, indium <In>, cesium <Ce>, hafnium <Hf>, tantalum <Ta>, tungsten <W>, bismuth <Bi>, silicon <Si> can be mentioned, and as the third component, for example, boron <B>, carbon <C>, aluminum <Al>, phosphorus <P ] Can be mentioned. When the Sn-containing material contains the second component element and the third component element, high battery capacity, excellent cycle characteristics and the like can be obtained.

  Among them, the Sn-containing material is preferably a material containing tin <Sn>, cobalt <Co> and carbon <C> as a constituent element (referred to as “SnCoC-containing material”). In the SnCoC-containing material, for example, the content of carbon is 9.9% by mass to 29.7% by mass, and the ratio of the content of tin and cobalt {Co / (Sn + Co)} is 20% by mass to 70% by mass It is. This is because a high energy density can be obtained. The SnCoC-containing material has a phase containing tin, cobalt and carbon, and the phase is preferably low crystalline or amorphous. Since this phase is a reaction phase capable of reacting with lithium, excellent properties are obtained by the presence of the reaction phase. The half-width (diffraction angle 2θ) of the diffraction peak obtained by X-ray diffraction of this reaction phase is 1 degree or more when the CuKα ray is used as the specific X-ray and the drawing speed is 1 degree / minute preferable. While lithium is occluded and released more smoothly, the reactivity with the organic electrolyte decreases. The SnCoC-containing material may include, in addition to the low crystalline or amorphous phase, a phase containing a single element or a part of each constituent element.

  Whether a diffraction peak obtained by X-ray diffraction corresponds to a reaction phase capable of reacting with lithium can be easily determined by comparing X-ray diffraction charts before and after an electrochemical reaction with lithium. be able to. For example, if the position of the diffraction peak changes before and after the electrochemical reaction with lithium, it corresponds to a reaction phase capable of reacting with lithium. In this case, for example, the diffraction peak of the low crystalline or amorphous reaction phase is observed between 2θ = 20 ° and 50 °. Such a reaction phase contains, for example, the above-described constituent elements, and is considered to be low in crystallization or amorphization mainly due to the presence of carbon.

  In the SnCoC-containing material, it is preferable that at least a part of carbon which is a constituent element be bonded to a metal element or a metalloid element. It is because aggregation and crystallization of tin etc. are suppressed. The bonding state of the elements can be confirmed, for example, by using X-ray photoelectron spectroscopy (XPS) using Al-Kα rays or Mg-Kα rays as a soft X-ray source. When at least a part of carbon is bonded to a metal element or a metalloid element or the like, a peak of a synthetic wave of carbon 1s orbital (C1s) appears in a region lower than 284.5 eV. In addition, energy calibration shall be carried out so that the peak of 4f orbital (Au4f) of a gold atom may be obtained at 84.0 eV. Under the present circumstances, since surface contamination carbon exists in the substance surface normally, the peak of C1s of surface contamination carbon is made into 284.8 eV, and the peak is used as an energy standard. In XPS measurement, the waveform of the C1s peak is obtained in a form including the surface contaminating carbon peak and the carbon peak in the SnCoC-containing material. Therefore, for example, analysis may be performed using commercially available software to separate the two peaks. In the analysis of the waveform, the position of the main peak present on the lowest binding energy side is used as the energy reference (284.8 eV).

  The SnCoC-containing material is not limited to a material (SnCoC) whose constituent elements are only tin, cobalt and carbon. SnCoC-containing materials are, for example, in addition to tin, cobalt and carbon, silicon <Si>, iron <Fe>, nickel <Ni>, chromium <Cr>, indium <In>, niobium <Nb>, germanium <Ge> One or more of titanium <Ti>, molybdenum <Mo>, aluminum <Al>, phosphorus <P>, gallium <Ga>, bismuth <Bi>, etc. may be contained as a constituent element.

  Besides SnCoC-containing materials, materials containing tin, cobalt, iron and carbon as constituent elements (hereinafter referred to as “SnCoFeC-containing materials”) are also preferable materials. The composition of the SnCoFeC-containing material is optional. For example, when the content of iron is set to be small, the content of carbon is 9.9% by mass to 29.7% by mass, the content of iron is 0.3% by mass to 5.9% by mass, The content ratio of tin and cobalt {Co / (Sn + Co)} is 30% by mass to 70% by mass. In addition, when the content of iron is set to a relatively large amount, the content of carbon is 11.9% by mass to 29.7% by mass, and the content ratio of tin, cobalt and iron {(Co + Fe) / (Sn + Co + Fe)} is The content ratio of cobalt and iron {Co / (Co + Fe)} is 9.9 mass% to 79.5 mass%. In such a composition range, high energy density can be obtained. The physical properties (half width etc.) of the SnCoFeC-containing material are the same as the physical properties of the above-mentioned SnCoC-containing material.

  In addition, examples of the material constituting the negative electrode include metal oxides such as iron oxide, ruthenium oxide and molybdenum oxide; and polymer compounds such as polyacetylene, polyaniline and polypyrrole.

  Among them, the material constituting the negative electrode preferably contains both a carbon material and a metal-based material for the following reasons. That is, a metal-based material, in particular, a material containing at least one of silicon and tin as a constituent element has the advantage of high theoretical capacity, but tends to undergo significant expansion and contraction during charge and discharge. On the other hand, carbon materials have the advantage of being difficult to expand and contract at the time of charge and discharge while having low theoretical capacity. Therefore, by using both the carbon material and the metal-based material, expansion and contraction during charge and discharge can be suppressed while obtaining high theoretical capacity (in other words, battery capacity).

The present disclosure can also be configured as follows.
[A01] << Lithium-ion secondary battery ... 1st mode >>
Equipped with a positive electrode active material and an organic electrolyte,
The positive electrode active material comprises an amorphous lithium phosphate compound containing lithium, phosphorus, element M ¹ and oxygen,
The element M ¹ is ^one element selected from the group consisting of nickel, cobalt, manganese, gold, silver and palladium,
A lithium ion secondary battery in which substantially no lithium oxide exists on the surface of the positive electrode active material.
[A02] The lithium ion secondary battery according to [A01], in which lithium carbonate is present on the surface of the positive electrode active material.
[A03] The organic electrolyte contains a solvent and an electrolyte salt,
The lithium ion secondary battery according to [A01] or [A02], wherein the electrolyte salt comprises lithium perchlorate.
[A04] The lithium ion secondary battery according to [A03], wherein the solvent comprises a carbonate solvent.
[A05] The lithium ion secondary battery according to [A04], wherein the solvent comprises ethylene carbonate and / or diethyl carbonate.
[A06] The lithium ion secondary battery according to any one of [A01] to [A05], wherein the positive electrode active material is coated with lithium nitride phosphate.
[A07] The lithium ion secondary battery according to any one of [A01] to [A06], in which charging is performed at 4.0 volts or more.
[B01] リ チ ウ ム Lithium ion secondary battery: Second mode
Equipped with a positive electrode active material and an organic electrolyte,
The positive electrode active material comprises an amorphous lithium phosphate compound containing lithium, phosphorus, element M ¹ and oxygen,
The element M ¹ is ^one element selected from the group consisting of nickel, cobalt, manganese, gold, silver and palladium,
Lithium ion secondary battery in which lithium carbonate exists on the surface of the positive electrode active material.
[B02] The organic electrolyte contains a solvent and an electrolyte salt,
The lithium ion secondary battery according to [B01], wherein the electrolyte salt comprises lithium perchlorate.
[B03] The lithium ion secondary battery according to [B02], wherein the solvent comprises a carbonate solvent.
[B04] The lithium ion secondary battery according to [B03], wherein the solvent comprises ethylene carbonate and / or diethyl carbonate.
[B05] The lithium ion secondary battery according to any one of [B01] to [B04], wherein the positive electrode active material is coated with lithium nitride phosphate.
[B06] The lithium ion secondary battery according to any one of [B01] to [B05], which is charged at 4.0 volts or more.
[C01] << lithium ion secondary battery: third aspect >>
Equipped with a positive electrode active material and an organic electrolyte,
The positive electrode active material comprises an amorphous lithium phosphate compound containing lithium, phosphorus, element M ¹ and oxygen,
The element M ¹ is ^one element selected from the group consisting of nickel, cobalt, manganese, gold, silver and palladium,
The organic electrolyte contains a solvent and an electrolyte salt,
Lithium ion secondary battery in which the electrolyte salt consists of lithium perchlorate.
[C02] The lithium ion secondary battery according to [C01], wherein the solvent comprises a carbonate solvent.
[C03] The lithium ion secondary battery according to [C02], wherein the solvent comprises ethylene carbonate and / or diethyl carbonate.
[C04] The lithium ion secondary battery according to any one of [C01] to [C03], wherein the positive electrode active material is coated with lithium nitride phosphate.
[C05] The lithium ion secondary battery according to any one of [C01] to [C04], which is charged at 4.0 volts or more.
[D01] << Lithium Ion Secondary Battery: Fourth Aspect >>
Equipped with a positive electrode active material and an organic electrolyte,
The positive electrode active material comprises an amorphous lithium phosphate compound containing lithium, phosphorus, element M ¹ and oxygen,
The element M ¹ is ^one element selected from the group consisting of nickel, cobalt, manganese, gold, silver and palladium,
The lithium ion secondary battery in which the positive electrode active material is coated with lithium nitride phosphate.
[D02] The lithium ion secondary battery according to [D01], which is charged at 4.0 volts or more.
[E01] "Battery pack"
The lithium ion secondary battery according to any one of [A01] to [D02],
A control unit that controls the operation of the lithium ion secondary battery;
A switch unit that switches the operation of the lithium ion secondary battery according to an instruction of the control unit;
Battery pack.
[E02] "Electric vehicle"
The lithium ion secondary battery according to any one of [A01] to [D02],
A converter that converts power supplied from a lithium ion secondary battery into driving power,
A driving unit driven according to the driving force, and
An electric vehicle including a control unit that controls the operation of a lithium ion secondary battery.
[E03] 電力 Power storage system》
The lithium ion secondary battery according to any one of [A01] to [D02],
One or more electric devices powered by a lithium ion secondary battery, and
Control unit for controlling the power supply to the electric device from the lithium ion secondary battery,
Power storage system.
[E04] "Power tool"
The lithium ion secondary battery according to any one of [A01] to [D02], and
Movable part powered by lithium ion secondary battery,
Equipped with a power tool.
[E05] "Electronics"
An electronic device comprising the lithium ion secondary battery according to any one of [A01] to [D02] as a power supply source.

1: positive electrode, 1A: positive electrode current collector, 1B: positive electrode active material layer, 1C: lithium nitride phosphate layer, 2: negative electrode, 3: separator, 4. Organic electrolytic solution (non-aqueous electrolytic solution), 11 · · · battery can, 12, 13 · · · insulating plate, 14 · · · battery cover, 15 · · · safety valve mechanism, 15A · · · disk plate, 16 · · ·・ Heat sensitive resistance element (PTC element) 17, 17: gasket, 20: wound electrode body, 21: positive electrode, 21A: positive electrode current collector, 21B: positive electrode active material layer, 22 ... Anode, 22A: anode current collector, 22B: anode active material layer, 23: separator, 24: center pin, 25: cathode lead, 26: anode lead, 211 ... positive electrode active material, 212 ... active material insulating layer, 213 ... negative electrode insulating layer, 214 ... separete Insulating layer, 30: wound electrode body, 31: positive electrode lead, 32: negative electrode lead, 33: positive electrode, 33A: positive electrode current collector, 33B: positive electrode active material layer, 34: negative electrode, 34A: negative electrode current collector, 34B: negative electrode active material layer, 35: separator, 36: electrolyte layer, 37: protective tape, 40: exterior member , 41: adhesive film, 60: housing, 61: control unit, 62: power source, 63: switch unit, 64: current measurement unit, 65: temperature detection unit , 66: voltage detection unit, 67: switch control unit, 68: memory, 69: temperature detection element, 70: current detection resistor, 71: positive electrode terminal, 72: ... Negative electrode terminal 73: housing: 74: control unit 75: engine 76: power supply 77: , 78: differential, 79: generator, 80: transmission, 81: clutch, 82, 83: inverter, 84: various sensors, 85: front wheel Drive shaft 86: front wheel 87: rear wheel drive shaft 88: rear wheel 89: house 90: controller 91: power supply 92: Smart meter, 93: power hub, 94: electric device (electronic device), 95: private generator, 96: electric vehicle, 97: centralized power system, 98: tool body , 99: control unit, 100: power source, 101: drill portion, 111: power source, 116: circuit board, 112: positive electrode lead, 113: negative electrode lead, 118, 119 · · · adhesive tape, 114 · · · tab, 115 · · · tab, 117 · · · · Lead wire with connector, 120 · · · Label, 121 · · · · · · · · · · · control section, 122 · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · Positive terminal, 126 ··· Temperature detection element, 127 · · · Negative terminal

Claims (6)

Equipped with a positive electrode active material and an organic electrolyte,
The positive electrode active material comprises an amorphous lithium phosphate compound containing lithium, phosphorus, element M ¹ and oxygen,
The element M ¹ is ^one element selected from the group consisting of nickel, cobalt, manganese, gold, silver and palladium,
Lithium oxide is substantially absent on the surface of the positive electrode active material, lithium carbonate is present on the surface of the positive electrode active material, and lithium oxide is measured by X-ray photoelectron spectroscopy of the positive electrode active material. The peak intensity ratio of the peak number of the oxygen atom derived from is 258 or less and defined by (count number of the peak of oxygen atom derived from lithium oxide) / (count number of the peak of oxygen atom derived from lithium carbonate) is Less than 0.05,
A lithium ion secondary battery, wherein the organic electrolyte comprises a solvent and an electrolyte salt, and the electrolyte salt comprises lithium perchlorate.   The lithium ion secondary battery according to claim 1, wherein the solvent comprises a carbonate solvent.   The lithium ion secondary battery according to claim 2, wherein the solvent comprises ethylene carbonate and / or diethyl carbonate.   The lithium ion secondary battery according to claim 1, wherein the positive electrode active material is coated with lithium nitride phosphate.   The lithium ion secondary battery according to claim 1, wherein charging is performed at 4.0 volts or more. The lithium ion secondary battery according to any one of claims 1 to 5, wherein the positive electrode active material is a lithium phosphate compound represented by the following formula (1) or (2).
Li _x Ni _y P o _z (1)
Here, 0 <X <8, 2 ≦ Y ≦ 10, and Z is a ratio in which oxygen is stably contained according to the composition ratio of Ni and P.
Li _x Cu _y PO ₄ (2)
Here, 0.5 ≦ X ≦ 7.0 and 1 ≦ Y ≦ 4.

Images