JP5733915B2 - Lithium ion secondary battery - Google Patents

Description

  The present invention relates to a non-aqueous electrolyte type lithium ion secondary battery using a lithium compound as a positive electrode active material.

Lithium ion secondary batteries such as mobile phones, notebook computers, portable tools such as electric tools, next-generation vehicles such as electric vehicles (EV) and hybrid vehicles (HEV), load leveling devices such as solar power generation and wind power generation Applications are increasingly expanding. In addition, in lithium ion secondary batteries, cell size, capacity, and output are increasing. In a conventional lithium ion secondary battery, lithium cobaltate (LiCoO ₂ ) has been mainly used as a positive electrode material (see, for example, Patent Document 1). However, a new positive electrode material that replaces lithium cobalt oxide has been demanded from the problem that cobalt raw materials are scarce and expensive in terms of resources and the safety problem caused by the crystal structure of lithium cobalt oxide. In addition, positive electrode materials such as lithium nickelate (LiNiO ₂ ) that can achieve higher capacity than lithium cobaltate and spinel-type lithium manganate (LiMn ₂ O ₄ ) that is inexpensive and excellent in thermal stability are also available. Use is progressing.

In recent years, new materials have been developed with the aim of achieving higher performance. Among them, low-cost, high-safety olivine-type lithium phosphate compounds (LiFePO ₄ and LiMnPO ₄ ) are attracting attention as new positive electrode active materials, and secondary batteries using them are practically used in power tools and the like. It has become.

JP 2001-338692 A

By the way, in the lithium ion secondary battery using the lithium compound described above as the positive electrode active material, the acid (mainly hydrogen fluoride) slightly contained in the electrolyte causes the lithium compound to react and cause deterioration of the battery characteristics. There is a problem such as. Specifically, in a lithium ion secondary battery, an electrolytic solution containing a lithium salt (for example, lithium hexafluorophosphate expressed as LiPF ₆ ) is used. However, hydrogen fluoride is produced as a reaction product in producing this lithium hexafluorophosphate. For this reason, in the electrolytic solution using lithium hexafluorophosphate which is generally commercially available, hydrogen fluoride which is an acid is slightly contained in the electrolytic solution. Therefore, in order to realize a lithium ion secondary battery with high output and little characteristic deterioration, it is necessary to take measures to remove hydrogen fluoride contained in the electrolytic solution. However, even if the hydrogen fluoride in the electrolyte is removed, the lithium salt will be hydrolyzed if water is mixed during battery assembly or if a small amount of water is mixed through the sealed portion of the container during long-term use. It decomposes and hydrogen fluoride is newly generated. As a result, the hydrogen fluoride and the lithium compound react to cause deterioration of the battery characteristics.

  This invention is made | formed in view of said subject, The objective is to provide the lithium ion secondary battery which has the outstanding battery performance.

Means [1] to [ 2 ] for solving the above problems are listed below.

[1] using the lithium compound as a positive electrode active material, accommodates the hydrogen fluoride removal agent to remove the hydrogen fluoride in the battery and the hydrogen fluoride removed material is placed in a state of being insulated from the positive electrode and the negative electrode In the non-aqueous electrolyte type lithium ion secondary battery, the battery contains a winding structure including the positive electrode, the negative electrode, and a separator separating them, and the hydrogen fluoride removing material As a container that contains particulate weak basic resin that reacts with hydrogen fluoride and has resistance to electrolytic solution, the electrolytic solution can pass through and Using a bag-like container made of an insulating separator material, the bag-like container in a state of containing the particulate weakly basic resin is disposed at a position facing the end surface of the wound structure. It is characterized by Lithium ion secondary battery.

In a lithium ion secondary battery, hydrogen fluoride may be contained in the electrolyte filled in the battery at the time of assembly, or hydrogen fluoride may be newly generated by a small amount of moisture that has entered the battery. In this case, in the invention described in the means 1 , since hydrogen fluoride is removed by the hydrogen fluoride removing material disposed in the battery, the hydrogen fluoride reacts with the positive electrode active material and the battery performance deteriorates. Can be avoided. Further, since the hydrogen fluoride removing material is disposed in a state insulated from the positive electrode and the negative electrode, a local battery is not formed by the electrode active material and the hydrogen fluoride removing material, and the battery capacity is reduced. Can be prevented.

According to the invention described in the above means 1 , the hydrogen fluoride removing material is disposed in the battery in a state in which the electrolytic solution can pass therethrough and is accommodated in an insulating container. The hydrogen fluoride removing material is disposed in a state of being insulated from the positive electrode and the negative electrode in the container. Therefore, a local battery is not formed by the electrode active material and the hydrogen fluoride removing material, and a reduction in battery capacity can be prevented.

[ 2 ] The lithium ion secondary battery according to means 1 , wherein the lithium compound is an olivine type lithium phosphate compound.

According to the invention described in Means 2 , since the olivine type lithium phosphate compound is used as the positive electrode active material, a lithium ion secondary battery can be manufactured at low cost. In particular, when the lithium compound is lithium iron phosphate, the material cost can be suppressed. In addition, the olivine-type lithium phosphate compound has a relatively stable crystal structure, but has a low ionic conductivity. For this reason, when using an olivine type lithium phosphate compound as a positive electrode active material, it is more preferable to cover the surface of the lithium compound with a carbon coating layer.

In the inventions described in the above means 1 and 2 , since the hydrogen fluoride removing material is a weakly basic resin such as polyvinyl pyridine resin, hydrogen fluoride can be reliably removed by a neutralization reaction. it can. In addition, weakly basic resins such as polyvinyl pyridine resin are materials having excellent resistance to electrolytic solution, so that even when placed in the electrolytic solution, they do not dissolve and can reliably remove hydrogen fluoride. .

As described above in detail, according to the invention described in any one of means 1 to 2 , a lithium ion secondary battery having excellent battery performance can be provided.

Sectional drawing which shows the lithium ion secondary battery of Example 1 in 1st Embodiment. The expanded sectional view which shows an electrode structure. The schematic diagram which shows the structure of the particle | grains of a positive electrode active material. Sectional drawing which shows the lithium ion secondary battery of Example 2 in 1st Embodiment. The side view which shows the lithium ion secondary battery of 2nd Embodiment. The top view which shows the lithium ion secondary battery of 2nd Embodiment. Sectional drawing which shows the electrode structure of 2nd Embodiment.

[First Embodiment]
Hereinafter, a first embodiment in which the present invention is embodied in a non-aqueous electrolyte type lithium ion secondary battery will be described in detail with reference to the drawings. FIG. 1 is a cross-sectional view showing a lithium ion secondary battery 10 according to the present embodiment, and FIG. 2 is an enlarged cross-sectional view showing an electrode structure 11 constituting the lithium ion secondary battery 10.

As shown in FIGS. 1 and 2, the lithium ion secondary battery 10 includes an electrode structure (winding structure) 11 and a lithium salt (for example, lithium hexafluorophosphate expressed as LiPF ₆ ). And a metal battery can 12 that houses the electrode structure 11 together with the electrolytic solution. The electrode structure 11 includes a positive electrode 21, a negative electrode 31, and a separator 41 interposed between the positive electrode 21 and the negative electrode 31, and is wound in a roll shape with the positive electrode 21, the separator 41, and the negative electrode 31 being overlapped. Turn.

  The battery can 12 is a negative electrode can that is formed in a bottomed cylindrical shape and functions as a negative electrode terminal. The opening of the battery can 12 is sealed by a sealing body 17 including a positive terminal plate 13, a conductive partition plate 14, a conductive fixing plate 15, and a resin gasket 16.

  The positive electrode 21 has a structure in which a positive electrode material 22 made of a material containing lithium iron phosphate as a positive electrode active material is formed on a positive electrode current collector 23. The positive electrode current collector 23 is an electrode sheet for collecting current while supporting the positive electrode material 22, and is formed using a long strip-shaped conductive metal foil made of, for example, aluminum. The positive electrode current collector 23 is connected to the conductive fixing plate 15 through the conductive leads 18.

  The negative electrode 31 has a structure in which a negative electrode material 32 made of a material capable of inserting and extracting lithium ions (a carbon material such as graphite) is formed on a negative electrode current collector 33. The negative electrode current collector 33 is an electrode sheet for collecting current while supporting the negative electrode material 32, and is formed using a long strip-shaped conductive metal foil made of, for example, copper. The negative electrode current collector 33 is connected to the battery can 12 via the conductive lead 19.

  The separator 41 is made of a non-conductive porous body having durability against an electrolytic solution, an electrode active material, and the like and having continuous air holes. Usually, a nonwoven fabric or a porous body made of cellulose, such as glass fiber, polyethylene, polypropylene, or the like is used. The separator 41 of the present embodiment has a three-layer structure in which a polyvinyl pyridine resin 43 is sandwiched between two separator materials 42. In the present embodiment, the polyvinylpyridine resin 43 is a granular material that functions as a hydrogen fluoride removing material, and is disposed between the two separator materials 42 so as to be insulated from the positive electrode 21 and the negative electrode 31. It has become.

  Next, the manufacturing method of the lithium ion secondary battery 10 of this Embodiment is demonstrated.

First, as a positive electrode active material, a powder material of lithium iron phosphate (LiFePO ₄ ) particles 100 (see FIG. 3) having a carbon coating layer 101 is prepared by the following method. That is, iron oxalate dihydrate (FeC ₂ O ₄ .2H ₂ O), ammonium dihydrogen phosphate (NH ₄ H ₂ PO ₄ ) and lithium carbonate (Li ₂ CO ₃ ) were measured so as to have a predetermined molar ratio. Take and mix them. Thereafter, the mixture is pulverized and mixed in a ball mill for 10 hours using 2-propanol as a solvent. Next, this mixture is vacuum-dried to remove 2-propanol as a solvent to obtain an active material precursor.

Then, the obtained precursor was put into an alumina casserole, and pre-baked at 300 ° C. for 5 hours in an annular baking furnace under argon flow (flow rate of 0.5 liter / min). Then, the powder of lithium iron phosphate which had the carbon coating layer 101 was produced by baking for 20 hours at 650 degreeC under argon circulation (0.5 liter / min distribution | circulation amount). In addition, as shown in FIG. 3, the particle 100 of the lithium iron phosphate obtained here is covered with a phosphorus compound 102 mainly composed of Fe ₂ P, and the surface of the phosphorus compound 102 is partially covered. A carbon coating layer 101 is formed. In this way, by partially forming the carbon coating layer 101 in the particle 100, a path through which lithium ions enter and exit is ensured. Further, when the carbon coating layer 101 contacts between the adjacent particles 100, a path of electrical conduction is formed.

  Next, using the lithium iron phosphate powder as a positive electrode active material, a sheet-like positive electrode 21 is prepared as follows. First, N-methylpyrrolidone was measured in a predetermined weight ratio (positive electrode active material: conductive agent: binder = 90: 5: 5) with respect to the positive electrode active material, acetylene black as a conductive agent, and polyvinylidene fluoride as a binder. Was added and mixed with a planetary stirring mixer with a disperser for 30 minutes to form a slurry. Then, the obtained slurry is applied onto an aluminum foil as the positive electrode current collector 23 and then dried. Then, it rolls using a rolling roller, Furthermore, the positive electrode 21 in which the positive electrode material 22 (positive electrode active material content layer) was formed on the positive electrode current collector 23 is produced by attaching the conductive lead 18.

  Subsequently, the sheet-like negative electrode 31 is produced as follows. First, graphite as a negative electrode active material and polyvinylidene fluoride as a binder (binder) were mixed, and N-methylpyrrolidone was added to form a slurry. At this time, the mixing ratio was 95: 3: 2 by weight ratio of the negative electrode active material, the binder, and the thickener, and the slurry was prepared. Then, the obtained slurry is applied onto a copper foil as the negative electrode current collector 33 and then dried. Then, it rolls using a rolling roller, Furthermore, the negative electrode 31 in which the negative electrode material 32 (negative electrode active material content layer) was formed on the negative electrode collector 33 is produced by attaching the conductive lead 19.

  Further, the separator base paper is cut into a predetermined size to prepare a sheet-like separator material 42 and a granular polyvinyl pyridine resin 43 is prepared. Then, with the polyvinyl pyridine resin 43 uniformly applied between the two separator materials 42, the outer edge portions of the two separator materials 42 are bonded using a technique such as heat fusion. As a result, the separator 41 having a three-layer structure in which the polyvinyl pyridine resin 43 is sandwiched between the separator materials 42 is produced.

The electrolytic solution is prepared as follows. Specifically, 1 mol / liter of lithium salt (LiPF ₆ ) is dissolved in a solvent in which ethylene carbonate and ethyl methyl carbonate are mixed at a volume ratio of 3: 7, and vinylene carbonate is added to the electrolyte solution. Was prepared.

  And the lithium ion secondary battery 10 was produced as follows using the positive electrode 21, the negative electrode 31, the separator 41, and electrolyte solution.

  First, the obtained electrode bodies of the sheet-like positive electrode 21 and negative electrode 31 are dried in a vacuum at 80 ° C. for 20 hours. And the positive electrode 21 and the negative electrode 31 are wound in roll shape through the separator 41, and the electrode structure 11 is produced. Next, the electrode structure 11 is inserted into the battery can 12, and the conductive leads 18 and 19 are connected to the conductive fixing plate 15 and the battery can 12, respectively. Thereafter, a predetermined amount of electrolytic solution is injected into the battery can 12, and the opening of the battery can 12 is sealed with the sealing body 17. Through the above steps, the lithium ion secondary battery 10 of FIG. 1 is manufactured.

  Next, the operation of the lithium ion secondary battery 10 will be described.

When water is mixed in the battery can 12 during battery assembly or a small amount of water is mixed through the sealing portion of the battery can 12 during long-term use, the lithium salt is hydrolyzed to produce hydrogen fluoride. Is done. Here, the hydrolysis of the lithium salt occurs according to the following reaction formulas (1) to (3).

In addition, when said reaction formula (1)-(3) is put together, hydrolysis of lithium salt is represented like reaction formula (4).

Thus, when hydrogen fluoride is newly generated in the electrolytic solution, the hydrogen fluoride is polyvinyl pyridine resin 43 disposed in the separator 41 as shown in the reaction formula (5). React with. As a result, polyvinyl biridinium poly (hydrogen fluoride) is generated, and hydrogen fluoride in the electrolytic solution is removed.

  As described above, since hydrogen fluoride in the electrolytic solution is removed, in the positive electrode material 22, the phosphorus compound 102 interposed between the lithium iron phosphate particles 100 and the carbon coating layer 101 reacts with hydrogen fluoride. Therefore, the carbon coating layer 101 is held on the particle surface.

  Further, the present inventors produced a lithium ion secondary battery 10A (Example 2) as shown in FIG. 4 as an embodiment different from the above-described lithium ion secondary battery 10 (Example 1). . In the lithium ion secondary battery 10 </ b> A of FIG. 4, in the battery can 12, an excess space is provided between the electrode structure 11 and the sealing body 17 (in FIG. 4, the upper part of the accommodation space of the electrode structure 11). And the bag-shaped container 45 which accommodated the granular polyvinyl pyridine resin 43 in the surplus space is arrange | positioned. In this case, the container 45 of the polyvinyl pyridine resin 43 is disposed at a position facing the end surface of the cylindrical electrode structure 11. The container 45 is made of an insulating material through which an electrolytic solution can flow. Specifically, it is formed into a bag shape using the same material as the separator 41. In the lithium ion secondary battery 10 </ b> A, the separator 41 constituting the electrode structure 11 is formed using a single separator material 42 that does not include the polyvinyl pyridine resin 43. The other configuration of the lithium ion secondary battery 10A is the same as that of the lithium ion secondary battery 10 of the first embodiment.

  Furthermore, the present inventors added a granular material of polyvinyl pyridine resin 43 at a rate of 100 mg to 1 g of the electrolytic solution adjusted as described above, and used the electrolytic solution left for 24 hours to use a lithium ion secondary battery ( Comparative Example 1) was prepared. In the lithium ion secondary battery of Comparative Example 1, a separator that does not include the polyvinyl pyridine resin 43 is used as the separator 41, and the other configurations are the same as those of the lithium ion secondary battery 10 of Example 1.

The characteristics of the lithium ion secondary batteries 10 and 10A of Examples 1 and 2 and Comparative Example 1 were evaluated. Specifically, at a test temperature of 45 ° C., charging consisting of charging until the battery voltage reaches 4.0 V at a constant current of 1 C and discharging until the battery voltage reaches 2.0 V at a constant current of 1 C. The discharge cycle is repeated 1000 times. Then, the change rate of the discharge capacity and internal resistance of each battery 10 of Examples 1 and 2 and Comparative Example 1 was measured. The measurement results are shown in Table 1. In Table 1, the change rate (maintenance rate) of the discharge capacity and the change rate of the internal resistance after the charge / discharge test are described with the discharge capacity and the internal resistance in the initial state before the start of the test as 100% .

  As shown in Table 1, in the lithium ion secondary batteries 10 and 10A of Example 1 and Example 2 in which the polyvinyl pyridine resin 43 is disposed in a state insulated from the positive electrode 21 and the negative electrode 31 in the battery, Compared with the lithium ion secondary battery, it was possible to maintain a high discharge capacity and to keep the internal resistance low. Specifically, in the lithium ion secondary battery of Comparative Example 1, the polyvinyl pyridine resin 43 is added to the electrolytic solution, and a part of the added polyvinyl pyridine resin 43 is in contact with the positive electrode 21 and the negative electrode 31. It is in a state. In this case, since the local battery is formed by the polyvinyl pyridine resin 43 and the active materials of the positive electrode 21 and the negative electrode 31, the discharge capacity of the entire battery is reduced. On the other hand, in the lithium ion secondary batteries 10 and 10A of Example 1 and Example 2, since the polyvinyl pyridine resin 43 is insulated from the electrode, the reaction with the active material is prevented, and the discharge capacity is reduced. It can be kept low.

  Therefore, according to the present embodiment, the following effects can be obtained.

  (1) Since lithium iron phosphate is used as the positive electrode active material in the lithium ion secondary batteries 10 and 10A of the present embodiment, the material cost can be suppressed. Moreover, in the lithium ion secondary battery 10 of Example 1, the polyvinyl pyridine resin 43 is provided in the separator 41 which separates the positive electrode 21 and the negative electrode 31. Furthermore, in the lithium ion secondary battery 10 of Example 2, a container 45 containing the polyvinyl pyridine resin 43 is disposed in a surplus space other than the storage space of the electrode structure 11 in the battery. As described above, when the polyvinyl pyridine resin is provided in the lithium ion secondary battery 10, hydrogen fluoride generated by hydrolysis of the lithium salt is removed by the polyvinyl pyridine resin 43. Therefore, the phosphorus compound 102 interposed between the lithium iron phosphate particles 100 and the carbon coating layer 101 does not react with hydrogen fluoride and dissolve, and the carbon coating layer 101 peels off from the particle surface. Can be avoided. As a result, since the ionic conductivity in the positive electrode material 22 is well maintained, the active material of the positive electrode material 22 is effectively used, and good battery performance can be maintained.

  (2) In the lithium ion secondary battery 10 of Example 1, the polyvinylpyridine resin 43 is disposed in a state of being sandwiched between the two separator members 42 constituting the separator 41, and the positive electrode 21 and the negative electrode 31. It is in a non-contact state. Also in the lithium ion secondary battery 10A of Example 2, the polyvinyl pyridine resin 43 is accommodated in the insulating container 45, and the polyvinyl pyridine resin 43, the positive electrode 21, and the negative electrode 31 are not in contact with each other. It has become. If comprised in this way, a local battery will not be formed with an electrode active material and the polyvinyl pyridine resin 43, and the fall of the discharge capacity of a battery can be prevented.

  (3) In the lithium ion secondary battery 10 </ b> A of Example 2, the container 45 containing the polyvinylpyridine resin 43 is disposed in the vicinity of the opening of the battery can 12. In this case, hydrogen fluoride contained in the electrolytic solution can be efficiently removed when the electrolytic solution is injected. In addition, hydrogen fluoride generated by moisture or the like entering from the sealing portion of the battery can 12 can be efficiently removed.

(4) In the lithium ion secondary batteries 10 and 10A of the present embodiment, the polyvinyl pyridine resin 43 is a granular material and has a large surface area. Moreover, since the polyvinyl pyridine resin 43 has electrolyte solution resistance, it can maintain the shape, without melt | dissolving in electrolyte solution. Therefore, hydrogen fluoride contained in the electrolytic solution can be efficiently removed by the granular polyvinyl pyridine resin 43.
[Second Embodiment]

  Hereinafter, a second embodiment of the present invention will be described in detail with reference to the drawings. FIG. 5 is a side view showing a lithium ion secondary battery 10B in the present embodiment, and FIG. 6 is a plan view of the lithium ion secondary battery 10B. FIG. 7 is a cross-sectional view showing an electrode structure 11A constituting the lithium ion secondary battery 10B.

As shown in FIGS. 5 to 7, the lithium ion secondary battery 10 </ b> B includes an electrode structure 11 </ b> A having a structure in which positive electrodes 21 and negative electrodes 31 formed in a sheet shape are alternately stacked via separators 41. A laminated structure). In the lithium ion secondary battery 10B, the electrode structure 11A is hermetically sealed in the case 51 together with an electrolytic solution containing a lithium salt (LiPF ₆ ).

  The positive electrode 21 has a structure in which a positive electrode material 22 made of a material containing lithium iron phosphate as a positive electrode active material is formed on a positive electrode current collector 23. The positive electrode current collector 23 is formed using a conductive metal foil made of, for example, aluminum. The positive electrode current collector 23 is formed in a rectangular shape in plan view, and a tab 24 projects from one of the four sides. The tab 24 of the positive electrode current collector 23 is connected to the positive electrode external terminal 25 by welding or the like.

  The negative electrode 31 has a structure in which a negative electrode material 32 made of a material capable of inserting and extracting lithium ions (a carbon material such as graphite) is formed on a negative electrode current collector 33. The negative electrode current collector 33 is formed using a conductive metal foil made of, for example, copper. The negative electrode current collector 33 is formed in a rectangular shape in plan view, and a tab 34 is drawn from one of the four sides. The tab 34 of the negative electrode current collector 33 is connected to the negative electrode external terminal 35 by welding or the like.

  The separator 41 of the present embodiment also has a three-layer structure in which a polyvinyl pyridine resin 43 is sandwiched between two separator materials 42. The polyvinyl pyridine resin 43 is a granular material that functions as a hydrogen fluoride removing material, and is disposed between the two separator materials 42 so as to be insulated from the positive electrode 21 and the negative electrode 31.

  As shown in FIGS. 5 and 6, the case 51 of the lithium ion secondary battery 10 </ b> B is a soft container processed into a rectangular bag shape using an aluminum laminate film obtained by laminating an aluminum foil on a resin film. The outer periphery of the case 51 is sealed by heat sealing. Sealing by thermal fusion is performed in a state where the positive electrode external terminal 25 and the negative electrode external terminal 35 are sandwiched between the fusion portions.

  When the electrode structure 11A is housed in the case 51 in this way, the positive electrode external terminal 25 is drawn out from one end (the left end in FIG. 5) of the case 51 and the other end (FIG. 5). Then, the negative external terminal 35 is pulled out from the right end). Note that the case 51 may be formed using a metal laminate film material made of a metal foil other than the aluminum foil.

  Also in the lithium ion secondary battery 10B of the present embodiment, when moisture is mixed in the case 51 during battery assembly or when a minute amount of water is mixed through the sealing portion of the case 51 during long-term use, The lithium salt is hydrolyzed to produce hydrogen fluoride. As shown in the reaction formula (5), the hydrogen fluoride reacts with the polyvinyl pyridine resin 43 disposed in the separator 41 to remove hydrogen fluoride in the electrolytic solution.

  Therefore, also in the present embodiment, as in the first embodiment, the phosphorus compound 102 interposed between the lithium iron phosphate particles 100 and the carbon coating layer 101 reacts and dissolves with hydrogen fluoride. And the problem that the carbon coating layer 101 peels off from the particle surface can be avoided. As a result, since the ionic conductivity in the positive electrode material 22 is well maintained, the active material of the positive electrode material 22 is effectively used, and good battery performance can be maintained. Moreover, since the polyvinyl pyridine resin 43 is in a non-contact state with the positive electrode 21 and the negative electrode 31, a local battery is not formed by the electrode active material and the polyvinyl pyridine resin 43, and the discharge capacity of the battery is reduced. Can be prevented.

  In addition, you may change each embodiment of this invention as follows.

  -In the said embodiment, although lithium iron phosphate was used as a positive electrode active material, it is not limited to this, For example, you may use olivine type lithium phosphate compounds, such as manganese phosphate lithium. Furthermore, lithium compounds such as lithium cobaltate and lithium nickelate may be used as the positive electrode active material.

  In each of the above embodiments, the granular material of the polyvinyl pyridine resin 43 is sandwiched in the separator 41, but the polyvinyl pyridine resin 43 formed in a plate shape may be sandwiched. Furthermore, when the polyvinyl pyridine resin 43 is formed in a plate shape, the polyvinyl pyridine resin 43 may be installed on a portion such as a bottom surface or a side surface of the battery can 12 or the case 51.

  In each of the above embodiments, the polyvinyl pyridine resin 43 is used as the hydrogen fluoride removing material. However, the present invention is not limited to this, and other weak materials that react with hydrogen fluoride and have resistance to an electrolytic solution. Any material mainly composed of a basic resin may be used. For example, as a material for removing hydrogen fluoride, a resin based on a reaction of a secondary amine such as dimethylamine following chloromethylation of a styrene resin (S-type weak base resin), or a polyalkyleneamine-type weak base functional group And a resin (P-type weak base resin) mainly composed of a phenol formaldehyde polymer containing In addition, a resin (E-type weak base resin) produced by the reaction of epichlorohydrin and polyalkyleneamine, or a poly having amine functional groups (that is, monoamine, diamine, or polyamine) bonded to the polymer structure by ester bond or amide bond. A resin mainly composed of acrylate (A-type weak base resin) may be used as the hydrogen fluoride removing material.

  Next, in addition to the technical ideas described in the claims, the technical ideas grasped by the respective embodiments described above are listed below.

  (1) A lithium ion secondary battery according to means 5, wherein the olivine type lithium phosphate compound is lithium iron phosphate.

  (2) The lithium ion secondary battery according to means 5, wherein the olivine type lithium phosphate compound is covered with a carbon coating layer.

  (3) The lithium ion secondary battery according to any one of means 1 to 5, wherein the hydrogen fluoride removing material is a polyvinyl pyridine resin.

  (4) The lithium ion secondary battery according to any one of means 1 to 5, wherein the separator is formed in a state where the hydrogen fluoride removing material is sandwiched between two separator materials.

  (5) The lithium ion secondary battery according to any one of means 1 to 5, wherein the hydrogen fluoride removing material has resistance to an electrolytic solution.

  (6) The lithium ion secondary battery characterized in that, in the means 4, the hydrogen fluoride removing material is disposed at a position facing the end face of the wound structure.

DESCRIPTION OF SYMBOLS 10,10A, 10B ... Lithium ion secondary battery 11 ... Electrode structure as winding structure 11A ... Electrode structure as laminated structure 21 ... Positive electrode 31 ... Negative electrode 41 ... Separator 43 ... As a hydrogen fluoride removing material Polyvinyl pyridine resin 45 ... container 100 ... particles of lithium iron phosphate as lithium compound

Claims (2)

A non-aqueous electrolyte in which a lithium compound is used as a positive electrode active material, a hydrogen fluoride removing material for removing hydrogen fluoride is accommodated in the battery, and the hydrogen fluoride removing material is insulated from the positive electrode and the negative electrode Type lithium ion secondary battery,
The battery contains a winding structure configured to include the positive electrode, the negative electrode, and a separator separating them,
As the hydrogen fluoride removing material, a particulate weak basic resin that reacts with hydrogen fluoride and has resistance to electrolytic solution is used.
As a container for containing the particulate weak basic resin, a bag-shaped container made of a separator material through which the electrolytic solution can pass and having an insulating property is used.
A lithium ion secondary battery, wherein the bag-shaped container in a state where the particulate weakly basic resin is accommodated is disposed at a position facing an end surface of the wound structure. The lithium ion secondary battery according to claim 1 , wherein the lithium compound is an olivine type lithium phosphate compound.

Images