JP2008192593A - Lithium polymer battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lithium polymer battery with a rate property, cycle property, and bulging prevention of a cell, or the like improved. <P>SOLUTION: The lithium polymer battery in which a gel electrolyte includes a solvent, a cross-linking polymer, and an organic compound as shown in the expression. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a lithium polymer battery, and more particularly to a lithium polymer battery in which a gel electrolyte contains an organic compound that improves battery characteristics.

  Lithium polymer batteries are attracting attention as power sources for mobile devices because they can be thinned, have a high degree of freedom in shape selection, and have a high level of safety by not using an electrolyte. Recently, with the increase in the functions of mobile devices used, higher energy and improved battery characteristics have become the goals of technological development.

  Among these, important technical issues include 1) improvement of safety, 2) improvement of charge / discharge cycle characteristics, and 3) improvement of high energy density. 1) In order to improve safety, it has been proposed to prevent leakage by trapping a flammable organic electrolyte in a gel polymer. For example, Patent Document 1 proposes a gel electrolyte composed of two kinds of low molecular weight acrylate monomers, and Patent Document 2 proposes a gel electrolyte composed of polypropylene glycol acrylate having 2 to 4 repeating units. Yes. Patent Document 3 proposes a gel electrolyte composed of an acrylic resin having a molecular weight of 5,000 to 500,000 and a crosslinking monomer (crosslinking monomer is in the range of 1 to 30% by mass). Describes an oligomer having a molecular weight of 10,000 to 25,000. Next, 2) the charge / discharge cycle characteristics have been improved by variously devising polymer materials to be used. In patent document 5, the improvement by mixing a physical crosslinkable polymer and a chemical crosslinkable gel electrolyte is proposed. In patent document 6, the improvement about the impregnation property of a pregel solution is proposed by modifying the separator surface to be used. In Non-Patent Document 1, for secondary batteries using a gel electrolyte, electrode materials (for example, artificial graphite (bulk graphite) which is expensive but has an effect of suppressing cell swelling) are used for the negative electrode material, cell shape, and the like. Is described, and suppression of cell swelling and improvement of charge / discharge cycle characteristics are described. 3) Regarding the increase in energy density, Patent Document 7 proposes that in lithium polymer batteries using physical gel, the capacity density is improved by appropriately defining the porosity of the gel electrolyte-active material composite electrode. ing. Thus, in a lithium polymer battery using a gel electrolyte, selection of not only the material of the gel electrolyte but also the electrode material, the cell shape, the cell preparation conditions, the electrolyte solution material, and the like is extremely important.

JP 2000-306604 A JP 2001-338690 A JP 2001-243835 A JP 2003-197262 A JP 2002-100406 A JP 2003-257490 A JP-A-11-307100 Supervised by Satoshi Kanamura, latest polymer battery technology II, p. 242-247, CM Publishing (2003)

  However, the lithium polymer battery using the above-described prior art has a defect that the ionic conductivity is inferior to that of the secondary battery using the electrolytic solution, so that the battery rate characteristics and charge / discharge cycle characteristics are inferior. It was also found that the charge / discharge cycle characteristics at high temperature and the storage characteristics in the charged state (hereinafter referred to as storage life) were not sufficient, and the cause was due to the increase in battery resistance. Therefore, it is necessary to design and manufacture a positive electrode, a negative electrode, an electrolytic solution, an electrolytic solution additive, a separator, and a battery using these according to the polymer material.

  The present invention has been made in view of the above problems. The problem of the present invention is that, when the gel electrolyte is applied to a lithium polymer battery, its ionic conductivity is lower than that of the liquid, so that the problematic rate characteristics, charge / discharge cycle characteristics improvement, cell swelling prevention, and high temperature The purpose is to improve the characteristics of the lithium polymer battery by a simple method against charge / discharge cycle characteristics and a decrease in storage life due to an increase in resistance, and to further improve the energy density of the lithium polymer battery.

  In order to solve the above problems, a lithium polymer battery of the present invention is a lithium polymer battery composed of at least a positive electrode, a negative electrode, a separator, and a gel electrolyte, and the gel electrolyte is represented by a solvent, a cross-linkable polymer, and Containing organic compounds.

However, in Chemical formula 1, Z is a halogen atom, a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, a polyfluoroalkyl group, a substituted or unsubstituted cyclic hydrocarbon having 4 to 20 carbon atoms, or XR ₅ ( Here, X represents an oxygen atom, a sulfur atom or NR ₆ , R ₆ represents a hydrogen atom or a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, and R ₅ represents a substituted or unsubstituted carbon atom having 4 to 20 carbon atoms. Represents a cyclic hydrocarbon. n represents an integer of 0 to 4. A ₁ and A ₂ are each independently an oxygen atom, a sulfur atom, or A ₁ is NR ₇ and A ₂ is NR ₈ (where R ₇ and R ₈ are each independently a hydrogen atom, a halogen atom, a substituted or unsubstituted atom) Represents an alkyl group having 1 to 10 carbon atoms, a polyfluoroalkyl group having 1 to 10 carbon atoms, or a substituted or unsubstituted cyclic hydrocarbon having 4 to 20 carbon atoms, and R ₇ and R ₈ are bonded to each other. A ring structure may be formed). L represents a methylene group or a single bond. M represents boron or phosphorus. B ₁ and B ₂ each independently represent a carbonyl group, a substituted or unsubstituted alkylene group or a polyfluoroalkylene group. m represents an integer of 1 to 3 (provided that 2m + n = 4 when M is boron and 2m + n = 6 when M is phosphorus).

In the lithium polymer battery of the present invention, when the positive electrode is composed mainly of lithium manganate as an active material, the positive electrode has a packing density of 2.5 g / cm ³ or more and 3.0 g / cm ³ or less. preferably, when the positive electrode is mainly composed of lithium cobaltate as an active material, the filling density of the positive electrode 3.3 g / cm ³ or more, preferably 3.8 g / cm ³ or less.

  Moreover, it is preferable that the lithium polymer battery of this invention has a peak which shows that boron and oxygen exist in 0.1 to 1.0 micrometer in the depth direction in the SIMS measurement of the surface of the said negative electrode.

  Moreover, it is preferable that the lithium polymer battery of this invention contains the decomposition product of the organic compound by which the peak of the boron in the said SIMS measurement and oxygen is shown by the said Chemical formula 1.

  In the lithium polymer battery of the present invention, the organic compound represented by Chemical Formula 1 preferably has a minimum unoccupied orbital energy (LUMO) of −1.5 eV or more and 0 eV or less.

  Further, in the lithium polymer battery of the present invention, the gel electrolyte is a solvent, a crosslinked polymer, 0.1 to 3.0% by mass of vinylene carbonate or a derivative thereof, and 0.05 to 5.0% by mass of Chemical 2 or An organic compound represented by Chemical Formula 1 such as an organic compound represented by Chemical Formula 3 may be contained.

  In the lithium polymer battery of the present invention, the positive electrode contains lithium manganate or lithium cobaltate as an active material, the cross-linked polymer is composed of an acrylic polymer, and the solvent is at least a chain carbonate and a cyclic carbonate. It is preferable that the negative electrode contains graphite as an active material and is covered with a laminate material.

  In a lithium polymer battery containing a gel electrolyte, the pregel solution that is a precursor of the gel electrolyte has an acrylic polymer having various functional groups, and an organic compound represented by Chemical Formula 1 in order to improve rate characteristics and charge / discharge cycle characteristics. By containing a compound, preferably an organic compound represented by Chemical Formula 2 or Chemical Formula 3, gas generation during initial charging can be suppressed, and the synergistic effect between the gel electrolyte, the positive electrode, the negative electrode, and the separator allows Delivery between the positive electrode and the negative electrode becomes smooth, and rate characteristics and charge / discharge cycle characteristics equivalent to the electrolyte can be provided.

  The synergistic effect here refers to the following. That is, the compound represented by Chemical Formula 1 reacts with the initial charge, and a film generally called a SEI (Solid Electrolyte Interface) film is formed on the negative electrode surface. By forming the film, the transfer between the negative electrode active material and the electrons becomes smooth. Also, the adhesion between the separator and each electrode is improved by mixing acrylic polymers with various functional groups (specifically, those with short chains, those with long chains, those with many polymer groups but short chains). To do. Specifically, impregnation is improved by the presence of short chains in the pores of the separator, and gelation ability is improved when there are those having a large number of polymer groups, and the polymer in the pores of the separator. The adhesion of the member is improved by reacting with. The above elements are synergistic and the characteristics are improved.

According to the present invention, in the lithium polymer battery, the gel electrolyte contains a solvent, a cross-linkable polymer, and an organic compound represented by Chemical Formula 1, so that it is not suitable for a battery using not only bulk graphite but also a conventional gel electrolyte. Even in the lithium polymer battery using the flaky graphite used as the negative electrode material, the organic compound represented by the chemical formula 1 covers the active site at the time of initial charging, so that gas generation can be suppressed and the cell swelling associated therewith can be reduced. . In addition, because of the synergistic effect between the gel electrolyte, the positive electrode, the negative electrode, and the separator, the transfer between the lithium positive electrode and the negative electrode is smooth, and the rate characteristics and charge / discharge cycle characteristics equivalent to those when using an electrolyte solution are achieved. Can be provided. Further, when the positive electrode contains lithium manganate, the positive electrode has a packing density of 2.5 g / cm ³ or more and 3.0 g / cm ³ or less, and when it contains lithium cobaltate, the positive electrode has a packing density of 3.3 g. If it is / cm ³ or more and 3.8 g / cm ³ or less, the rate characteristics and the like can be improved.

The positive electrode used in the lithium polymer battery of the present invention is obtained by applying a positive electrode active material layer to a current collector made of a metal such as an aluminum foil, and compressing and molding the dried material. The negative electrode is made of a copper foil or the like. A negative electrode active material is applied to a current collector made of a metal, dried, and compressed and molded. When the positive electrode active material contains lithium manganate, the packing density of the positive electrode is preferably 2.5 g / cm ³ or more and 3.0 g / cm ³ or less, and when lithium cobalt oxide is contained, 3.3 g / cm ³ or more 3 .8g / cm ³ or less, and when containing lithium manganate 2.8~2.9g / cm ^3, more preferably 3.6~3.7g / cm ³ in the case of containing lithium cobaltate . When the value is larger than the upper limit, the rate characteristics and the like are deteriorated. On the other hand, if it is smaller than the lower limit, the contact between the active materials becomes insufficient, the rate characteristics and the like are lowered, and it is difficult to increase the energy density. A separator will not be specifically limited if it is generally used with lithium polymer batteries, such as a nonwoven fabric and a polyolefin microporous film. A positive electrode and a negative electrode are stacked via a separator to produce a laminate, or a positive electrode and a negative electrode are wound flatly via a separator to form a wound body, and the laminate or the wound body is a laminate material, etc. A lithium polymer battery is prepared by injecting and treating the gel electrolyte after being put in the outer packaging material. In the above lithium polymer battery, a film is formed at the interface between the negative electrode active material and the polymer electrolyte by the initial charging, and this state is especially peaked by boron and oxygen in the depth direction from 0.1 to 1.0 μm by SIMS analysis of the negative electrode. (The detection value by SIMS analysis is preferably called a peak). In a battery that is not initially charged, boron and oxygen have a slight peak only on the outermost surface, and have little strength when the peak is normalized with carbon, which is a negative electrode material. This shows that the additive represented by Chemical Formula 1 is not decomposed. On the other hand, when the initial charge is performed, a broad peak of 0.1 to 0.5 μm in the electrode depth direction is observed. This suggests that the organic compound represented by Chemical Formula 1 is decomposed to form a film. Further, when a large amount of the organic compound represented by Chemical Formula 1 is added, it is suggested that a deeper film, that is, a thick film is formed than the above result, and the resistance at the negative electrode interface is increased, so that the battery characteristics are inferior. For SIMS analysis (secondary ion mass spectrometry), “ADEPT1010” manufactured by Physical Electronics was used, the primary ion species was O ₂ ⁺ , and the primary ion acceleration energy was 3 keV. As a pretreatment of the measurement sample, the lithium polymer battery was discharged to 3.0 V at 0.2 C (a battery having a certain capacity was discharged at a constant current, and when the discharge was completed in just one hour, the current was 1 C). The battery can be disassembled in a glove box in an argon gas atmosphere, and the negative electrode can be cut out and measured without exposure to the atmosphere.

  As the gelling component contained in the gel electrolyte, for example, a monomer having two or more polymerizable groups capable of thermal polymerization per molecule, an oligomer, a copolymerized oligomer, or the like can be given. As this gelling component, ethylene glycol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, tetraethylene glycol diacrylate, propylene diacrylate, dipropylene diacrylate, tripropylene diacrylate, which forms an acrylic polymer, Bifunctional acrylates such as 1,3-butanediol diacrylate, 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, and trifunctional acrylates such as trimethylolpropane triacrylate and pentaerythritol triacrylate, In addition, tetrafunctional acrylates such as ditrimethylolpropane tetraacrylate and pentaerythritol tetraacrylate, and the above-mentioned methacrylate. Tomonoma and the like. In addition to these, monomers such as urethane acrylate and urethane methacrylate, copolymer oligomers thereof, and copolymer oligomers with acrylonitrile are exemplified, but not limited thereto.

  In addition, polymers that can be dissolved in a plasticizer and gelled, such as polyvinylidene fluoride, polyethylene oxide, and polyacrylonitrile can also be used.

  The gel component is not limited to the above-described monomer, oligomer, or polymer, and any gel component that can be gelled can be used. Further, the gelation is not limited to one kind of monomer, oligomer or polymer, and it can be used by mixing 2 to several kinds of gel components as required.

  As a solvent contained in the gel electrolyte, cyclic carbonates such as propylene carbonate (PC), ethylene carbonate (EC), butylene carbonate (BC), and vinylene carbonate (VC), dimethyl carbonate (DMC), diethyl carbonate (DEC), Chain carbonates such as ethyl methyl carbonate (EMC) and dipropyl carbonate (DPC), aliphatic carboxylic acid esters such as methyl formate, methyl acetate and ethyl propionate, γ-lactones such as γ-butyrolactone, Chain ethers such as 2-ethoxyethane (DEE) and ethoxymethoxyethane (EME), cyclic ethers such as tetrahydrofuran and 2-methyltetrahydrofuran, dimethyl sulfoxide, 1,3-dioxolane, formamide, acetami Dimethylformamide, dioxolane, acetonitrile, propylnitrile, nitromethane, ethyl monoglyme, phosphoric acid triester, trimethoxymethane, dioxolane derivatives, sulfolane, methylsulfolane, 1,3-dimethyl-2-imidazolidinone, 3-methyl A mixture of one or more aprotic organic solvents such as 2-oxazolidinone, propylene carbonate derivative, tetrahydrofuran derivative, ethyl ether, 1,3-propane sultone, anisole, N-methylpyrrolidone, fluorinated carboxylate, etc. However, the present invention is not limited to these.

  Examples of the organic compound represented by Chemical Formula 1 to be included in the gel electrolyte include the organic compounds represented by Chemical Formula 2 and Chemical Formula 3, as well as the organic compounds shown in Table 1 as Compound Nos. 1 to 7, but the present invention includes these compounds. It is not limited.

  As the negative electrode active material, particularly when flake graphite is used, it has an active site unlike artificial graphite, and it causes gas generation every time charging / discharging occurs, causing cell expansion and capacity reduction. In a battery composed only of an electrolytic solution, VC, 1,3-propane sultone (hereinafter referred to as PS) or the like is generally used as a countermeasure. For example, PS has a minimum orbital energy (LUMO) of 0.07 eV, and decomposes to form a film before EC (LUMO: 1.18 eV) or DEC (LUMO: 1.26 eV), where PS is a solvent molecule. It is possible. As a result, decomposition of solvent molecules is suppressed, and suppression of battery swelling due to gas generation and improvement of rate characteristics can be expected. When dispersed in a polymer gel as in the system of the present invention, since the gel has a high resistance, the above-mentioned VC and PS are unlikely to form a decomposition film on the negative electrode (minimum empty orbit energy (LUMO): PS). (0.07 eV), VC: 0.09 eV). Therefore, a molecular additive having a LUMO smaller than that of PS or VC is desirable, and those having −1.5 eV or more and 0 eV or less are optimal. The organic compound represented by Chemical Formula 1 is considered to form a decomposition film on the electrode of the lithium ion secondary battery. For example, the minimum empty orbit energy (LUMO) of the organic compound represented by Chemical formula 2 is −1.21 eV, and EC (LUMO: 1.18 eV) or DEC (LUMO: 1) in which the organic compound represented by Chemical formula 2 is a solvent molecule. .26 eV) to decompose and form a film. As a result, the decomposition of the solvent molecules is suppressed, and the suppression of battery swelling due to gas generation and the improvement of the rate characteristics can be expected. Further, the minimum empty orbit energy (LUMO) of the organic compound represented by Chemical formula 3 is −0.24 eV. For example, when the positive electrode contains lithium manganate, the addition of an organic compound represented by chemical formula 1 such as chemical formula 2 or chemical formula 3 prevents Mn eluted in the gel from adsorbing on the negative electrode surface, resulting in resistance. It is thought that it is effective for suppressing the deterioration of the rate characteristics due to the rise and improving the charge / discharge cycle characteristics.

  In the present invention, vinylene carbonate or a derivative thereof is further appropriately contained in the gel electrolyte, which is effective for stabilizing a film formed of the organic compound represented by Chemical Formula 1 such as Chemical Formula 2 or Chemical Formula 3. Vinylene carbonate is particularly effective when lithium cobaltate is used for the positive electrode, and the concentration of vinylene carbonate contained is preferably 0.1% by mass or more and 3.0% by mass or less, particularly preferably 0.1% by mass. The content is 1.0% by mass or less.

  In the present invention, the gel electrolyte can further contain a cyclic sulfonate ester, a cyclic disulfonate ester or a chain disulfonate ester to stabilize the film formed by the organic compound represented by Chemical Formula 2 or Chemical Formula 3. It is valid. In particular, the effect is large when lithium cobaltate is used for the positive electrode, and the concentration of the sulfonic acid ester contained is preferably 0.1% by mass or more and 3.0% by mass or less, and particularly preferably 0.1% by mass or more and 1% by mass. 0.0 mass% or less.

  The concentration of the organic compound represented by Chemical Formula 1 such as Chemical Formula 2 or Chemical Formula 3 contained in these gel electrolytes is not particularly limited, but a secondary using a positive electrode containing lithium manganate as the positive electrode active material. In the case of a battery, 0.05 mass% or more and 5.0 mass% or less are preferable, More preferably, 0.5 mass% or more and 1.0 mass% or less are especially preferable. If it is less than 0.05 mass%, a sufficient film is not formed on the electrode surface, and the effect of improving charge / discharge cycle characteristics and rate characteristics is small. If it exceeds 5.0% by mass, the resistance increases and the rate characteristics deteriorate.

  When lithium cobaltate is used as the positive electrode active material, the concentration of the organic compound represented by Chemical Formula 2 contained in the gel electrolyte is not particularly limited, but is 0.05% by mass or more and 5.0% by mass. The following is preferred. If it is less than 0.05 mass%, a sufficient film is not formed on the electrode surface, and the effect of improving charge / discharge cycle characteristics and rate characteristics is small. If it exceeds 5.0% by mass, the resistance increases and the rate characteristics deteriorate.

The supporting salt contained in the gel electrolyte is not particularly limited, but electrolytes generally used for lithium polymer batteries such as LiPF ₆ , LiBF ₄ , LiAsPF ₆ , LiCF ₃ SO ₃ , LiN (CF ₃ SO ₂ ) ₂ can be used. .

  In the present invention, benzoins, peroxides and the like can be used as thermal polymerization initiators as necessary, but are not limited thereto.

Further, as the positive electrode active material, for example, LiCoO ₂ , LiNi _1-x Co _x O ₂ , LiMn ₂ O ₄ , LiNi _x Mn _2−x O ₄ (0 ≦ X ≦ 1) composite oxide positive electrode material can be used. However, it is not limited to these.

  Examples of the negative electrode active material include, but are not limited to, graphite, amorphous carbon, silicon, silicon oxide, metallic lithium, and alloys thereof.

  As the separator, polyolefin such as polypropylene and polyethylene, porous film such as fluororesin, and the like can be used, but the separator is not limited thereto.

  The present invention will be described in detail by way of examples with reference to the drawings.

  FIG. 1 is a diagram illustrating the configuration of the positive electrode of the lithium polymer battery of the present invention, FIG. 2 is a diagram illustrating the configuration of the negative electrode of the lithium polymer battery of the present invention, and FIG. 3 is a diagram of the lithium polymer battery of the present invention. It is a figure explaining the structure of the battery element after winding, and FIG. 4 is a figure explaining the exterior process of the lithium polymer battery of this invention.

(Example 1)
First, the production of the positive electrode will be described with reference to FIG. A mixture of 85% by mass of LiMn ₂ O ₄ , 7% by mass of acetylene black as a conductive auxiliary and 8% by mass of polyvinylidene fluoride as a binder is added to N-methylpyrrolidone and further mixed to prepare a positive electrode slurry. did. This was applied to both surfaces of a 20 μm-thick Al foil 2 as a current collector by a doctor blade method so that the thickness after roll press treatment was 160 μm and the packing density was 2.8 g / cm ^3. The application part 3 was formed. In addition, the positive electrode active material non-application part 4 in which the positive electrode active material was not apply | coated to either surface was provided in both ends, and the positive electrode conductive tab 6 was provided in one positive electrode active material non-application part 4, and it was set as the positive electrode 1.

  Next, the production of the negative electrode will be described with reference to FIG. Nine methyl pyrrolidone was added and mixed with 90% by mass of flaky graphite and 10% by mass of polyvinylidene fluoride as a binder to prepare a negative electrode slurry. This was applied to both surfaces of a 10 μm-thick Cu foil 8 serving as a current collector so that the thickness after the roll press treatment was 120 μm, thereby forming a negative electrode active material coating portion 9. In addition, the negative electrode active material single-side application part 10 in which the negative electrode active material is not applied only on one side and the negative electrode active material non-application part 11 in which the negative electrode active material is not applied are provided on one end face of both ends, and the negative electrode conductive tab 12 is provided. Was attached to the negative electrode 7.

  The production of the battery element will be described with reference to FIG. Two separators 13 made of polyethylene having a film thickness of 12 μm and a porosity of 35% are welded and cut, and the cut portions are fixed to the core of the winding device and wound, and the tips of the positive electrode 1 and the negative electrode 7 are attached. Introduce. The positive electrode 1 and the negative electrode 7 are arranged such that the side where the electrode active material layer is formed on both sides is the front end side, the negative electrode is placed between the two separators, and the positive electrode is placed on the upper surface of the separator. Turned to form a battery element (hereinafter referred to as jelly roll (J / R)).

  This J / R was housed in an embossed laminate outer package as shown in FIG. 4, the sides of the laminate outer body were folded back, and heat fusion was performed leaving a portion for injecting the pregel solution.

The pregel solution is composed of 30% by mass of ethylene carbonate (EC) and 58% by mass of diethyl carbonate (DEC), and 1% by mass of the organic compound represented by Chemical Formula 2 with respect to an electrolyte solution comprising 12% by mass of LiPF ₆ as a lithium salt. Then, 3.8% by mass and 1% by mass of triethylene glycol diacrylate and trimethylolpropane triacrylate were added as gelling agents and mixed well, and then t-butyl peroxypivalate was added as a polymerization initiator in an amount of 0.0. It was prepared by mixing 5% by mass.

  Next, the pregel solution was injected from the injection portion and vacuum impregnation was performed to obtain a lithium polymer battery.

(Initial charge / discharge capacity measurement conditions)
The obtained lithium polymer battery was charged to a battery voltage of 4.2 V (charging conditions: current: 0.2 C, time 6.5 H (hour), temperature 20 ° C.), and discharged to a battery voltage of 3.0 V at 0.2 C. The discharge capacity at that time was taken as the initial capacity.

(Negative electrode surface analysis)
The discharged lithium polymer battery was disassembled under an argon atmosphere, and the negative electrode was cut out and subjected to SIMS analysis without exposure to the air. The values obtained by this analysis are as described above. In the battery not initially charged, boron and oxygen have a slight peak only on the outermost surface, and the peak is normalized with carbon, which is the negative electrode material. Then, it has almost no strength. This shows that the additive represented by Chemical Formula 1 is not decomposed. On the other hand, in the case of the initial charge, a broad peak is observed at 0.1 to 0.5 μm in the depth direction of the electrode. This suggests that the organic compound represented by Chemical Formula 1 is decomposed to form a film. In addition, when a large amount of the organic compound represented by Chemical Formula 1 is added, it is suggested that a deeper film than the above result, that is, a thick film is formed, and as a result, the resistance of the negative electrode interface increases and the battery characteristics are inferior. Become. Also, by comparing the strengths before and after the charge / discharge cycle test, the strength is the same if the level is stable, and if the SEI is excessively formed if it is deteriorated, the strength ratio is a large value. If shown, the strength decreases when it collapses. Table 2 shows values of boron and oxygen peaks in the depth direction according to SIMS analysis results.

(Rate characteristics)
The rate characteristics of the obtained lithium polymer battery are as follows: a battery charged to a battery voltage of 4.2 V is discharged at 0.2 C to a battery voltage of 3.0 V, the discharge capacity is 1, and the discharge rate (1.0 C) It was shown in Table 2 by the ratio with the discharge capacity obtained by discharging.

(Volume change rate and capacity maintenance rate in charge / discharge cycle test)
The cell volume change rate after the charge / discharge cycle test of the obtained lithium polymer battery is shown in Table 2 as a ratio with the cell volume after the charge / discharge cycle test, with the cell volume after the initial charge being 1.0. The conditions of the charge / discharge cycle test were as follows: charge: upper limit voltage 4.2V, current: 1C, time 2.5H, discharge: lower limit voltage 3.0V, current: 1C. The capacity retention rate is shown in Table 2 as a ratio of the discharge capacity (1C) at the 100th cycle to the discharge capacity (1C) at the first cycle. Table 2 shows the intensity ratio of the boron and oxygen peaks according to the SIMS analysis results after the cycle before the cycle.

(Storage life measurement, capacity recovery rate)
In the storage test of the obtained lithium polymer battery, first, charging and discharging were performed once at 0.2 C at room temperature. The discharge capacity at this time was 100. Furthermore, it charged to 4.2V at 0.2C, and after measuring the resistance of 1kHz in this state, it was left to stand in a 45 degreeC thermostat for 3 months. After standing, the battery was discharged again at 0.2C at room temperature with 3.0V as the lower limit, followed by charging with the upper limit set to 4.2V, and after measuring the resistance at 1 kHz, the rate of increase in cell resistance before and after storage was determined. Further, the battery was further discharged, and the discharge capacity after this charge was taken as the recovery capacity after storage. Table 3 shows the results of the cell volume increase rate, cell resistance increase rate, and capacity recovery rate in the 45 ° C. storage test.

(Example 2)
A cell was prepared and evaluated in the same manner as in Example 1 except that the gel electrolyte was adjusted so that the concentration of the organic compound represented by Chemical Formula 2 was 0.5% by mass.

(Example 3)
A cell was prepared and evaluated in the same manner as in Example 1 except that the gel electrolyte was adjusted so that the concentration of the organic compound represented by Chemical Formula 2 was 0.1% by mass.

Example 4
A cell was prepared and evaluated in the same manner as in Example 1 except that the gel electrolyte was adjusted so that the concentration of the organic compound represented by Chemical Formula 2 was 2.0% by mass.

(Example 5)
A cell was prepared and evaluated in the same manner as in Example 1 except that the gel electrolyte was adjusted so that the concentration of the organic compound represented by Chemical Formula 2 was 3.0% by mass.

(Example 6)
A cell was prepared and evaluated in the same manner as in Example 1 except that the gel electrolyte was adjusted so that the concentration of the organic compound represented by Chemical Formula 2 was 5.0% by mass.

(Example 7)
A cell was prepared and evaluated in the same manner as in Example 1 except that the gel electrolyte was adjusted so that the concentration of the organic compound represented by Chemical Formula 2 was 0.05% by mass.

(Example 8)
A cell was prepared and evaluated in the same manner as in Example 1 except that the negative electrode material used was massive graphite.

Example 9
A cell was prepared and evaluated in the same manner as in Example 5 except that the negative electrode material used was massive graphite.

(Example 10)
A cell was prepared and evaluated in the same manner as in Example 6 except that massive graphite was used as the negative electrode material.

(Comparative Example 1)
A lithium polymer battery was produced in the same manner as in Example 1 except that the concentration of the organic compound represented by Chemical Formula 2 in the pregel solution was 0% by mass.

(Comparative Example 2)
A cell was prepared and evaluated in the same manner as in Example 1 except that the gel electrolyte was adjusted so that the concentration of the organic compound represented by Chemical Formula 2 was 8.0% by mass.

(Comparative Example 3)
A cell was prepared and evaluated in the same manner as in Example 1 except that VC was used instead of the organic compound represented by Chemical Formula 2.

(Comparative Example 4)
A cell was prepared and evaluated in the same manner as in Example 1 except that PS was used instead of the organic compound represented by Chemical Formula 2.

(Comparative Example 5)
A cell was prepared and evaluated in the same manner as in Comparative Example 1 except that massive graphite was used as the negative electrode material.

(Comparative Example 6)
A cell was prepared and evaluated in the same manner as in Comparative Example 3 except that massive graphite was used as the negative electrode material.

(Comparative Example 7)
A cell was prepared and evaluated in the same manner as in Comparative Example 4 except that massive graphite was used as the negative electrode material.

  In the lithium polymer battery of the present invention, as shown in Examples 1 to 7 in Tables 2 and 3, when the concentration of the organic compound represented by Chemical Formula 2 is 0.05 to 5.0 mass%, It was found that the characteristics were clearly better than those of Comparative Examples 1 and 2 in which other concentrations of the organic compound represented by Chemical Formula 2 were added. In addition, as shown in Example 1, Comparative Example 3, and Comparative Example 4, when the organic compound represented by Chemical Formula 2 is used, the characteristics clearly are higher in rate characteristics than the system using VC and PS of the same concentration. It was found to be good. Moreover, as shown in Examples 1-7, when the organic compound shown by Chemical formula 2 was used, it turned out that the storage characteristic at high temperature improves compared with the comparative examples 3 and 4. FIG. This is because the boron and oxygen peak intensities obtained by SIMS measurement before and after the evaluation do not change, and therefore, the SEI formed in Chemical Formula 2 is stable even at high temperatures, thereby suppressing an increase in resistance.

  Moreover, the same tendency is seen in the case of using massive graphite (Examples 8 to 10 and Comparative Examples 5 to 7), which is said to have good characteristics, and in the case of using scale-like graphite. It became clear that even flake graphite, which was considered unsuitable for batteries using, exhibited good characteristics.

(Example 11)
A cell was prepared and evaluated in the same manner as in Example 1 except that the organic compound represented by Chemical Formula 3 was used instead of the organic compound represented by Chemical Formula 2.

(Example 12)
A cell was prepared and evaluated in the same manner as in Example 2 except that the organic compound represented by Chemical Formula 3 was used instead of the organic compound represented by Chemical Formula 2.

(Example 13)
A cell was prepared and evaluated in the same manner as in Example 3 except that the organic compound represented by Chemical Formula 3 was used instead of the organic compound represented by Chemical Formula 2.

(Example 14)
A cell was prepared and evaluated in the same manner as in Example 4 except that the organic compound represented by Chemical Formula 3 was used instead of the organic compound represented by Chemical Formula 2.

(Example 15)
A cell was prepared and evaluated in the same manner as in Example 5 except that the organic compound represented by Chemical Formula 3 was used instead of the organic compound represented by Chemical Formula 2.

(Example 16)
A cell was prepared and evaluated in the same manner as in Example 6 except that the organic compound represented by Chemical Formula 3 was used instead of the organic compound represented by Chemical Formula 2.

(Example 17)
A cell was prepared and evaluated in the same manner as in Example 7 except that the organic compound represented by Chemical Formula 3 was used instead of the organic compound represented by Chemical Formula 2.

(Example 18)
A cell was prepared and evaluated in the same manner as in Example 8 except that the organic compound represented by Chemical Formula 3 was used instead of the organic compound represented by Chemical Formula 2.

(Example 19)
A cell was prepared and evaluated in the same manner as in Example 9 except that the organic compound represented by Chemical Formula 3 was used instead of the organic compound represented by Chemical Formula 2.

(Example 20)
A cell was prepared and evaluated in the same manner as in Example 10 except that the organic compound represented by Chemical Formula 3 was used instead of the organic compound represented by Chemical Formula 2.

(Comparative Example 8)
A cell was prepared and evaluated in the same manner as in Comparative Example 2 except that the organic compound represented by Chemical Formula 3 was used instead of the organic compound represented by Chemical Formula 2.

  Table 4 shows the rate characteristics, capacity retention rate in the cycle test, and cell volume change rate for Examples 11 to 20 and Comparative Examples 1 and 8, and Table 5 shows the results of the 45 ° C. storage test evaluation.

  In the lithium polymer battery of the present invention, as shown in Examples 11 to 17 in Tables 4 and 5, when the concentration of the organic compound represented by Chemical Formula 3 is 0.05 to 5.0 mass%, It was found that the characteristics were clearly better than those of Comparative Examples 1 and 8 in which the organic compound represented by Chemical Formula 3 at other concentrations was added. Similarly to the organic compound represented by Chemical Formula 2 above, as shown in Example 11, Comparative Example 3 and Comparative Example 4, when the organic compound represented by Chemical Formula 3 was used, the same concentration of VC and PS were obtained. It was found that the rate characteristics were clearly better than the system used. Moreover, as shown in Examples 11-17, when the organic compound shown by Chemical formula 3 was used, it turned out that the shelf life characteristic in high temperature improves compared with the comparative example 1 and the comparative examples 3 and 4. . This is because, since the boron and oxygen peak intensities obtained by SIMS measurement before and after the evaluation did not change, the SEI formed by the organic compound represented by Chemical Formula 3 is stable even at high temperatures, so that an increase in resistance is suppressed. It is. Moreover, the same tendency is seen in the case where massive graphite, which is said to have good characteristics (Examples 18 to 20), and in the case where flaky graphite is used, the organic compound represented by Chemical Formula 3 is a conventional gel electrolyte. It became clear that even flake graphite, which was considered unsuitable for the battery used, showed good characteristics.

(Example 21)
The positive electrode in this example using lithium cobaltate as the positive electrode was produced as follows. N-methylpyrrolidone was added to and mixed with 87% by mass of LiCoO ₂ , 5% by mass of acetylene black as a conductive auxiliary material, and 8% by mass of polyvinylidene fluoride as a binder to prepare a positive electrode slurry. Other than that, a positive electrode and a negative electrode were produced in the same manner as in Example 1 to produce a cell. In addition, it produced so that the packing density of a positive electrode might be 3.6 g / cm < ³ >. Moreover, the pregel solution produced and evaluated the cell similarly to Example 1 except having set the mass of the organic compound shown by VC: 0.5 mass% and chemical formula 2 to 1.0 mass%.

(Example 22)
A cell was prepared and evaluated in the same manner as in Example 21 except that the gel electrolyte was adjusted so that the organic compound represented by Chemical Formula 2 was 0.5% by mass.

(Example 23)
A cell was prepared and evaluated in the same manner as in Example 21 except that the gel electrolyte was adjusted so that the organic compound represented by Chemical Formula 2 was 0.1% by mass.

(Example 24)
A cell was prepared and evaluated in the same manner as in Example 21 except that the gel electrolyte was adjusted so that the organic compound represented by Chemical Formula 2 was 2.0% by mass.

(Example 25)
A cell was prepared and evaluated in the same manner as in Example 21 except that the gel electrolyte was adjusted so that the organic compound represented by Chemical Formula 2 was 3.0% by mass.

(Example 26)
A cell was prepared and evaluated in the same manner as in Example 21 except that the gel electrolyte was adjusted so that the organic compound represented by Chemical Formula 2 was 5.0% by mass.

(Example 27)
A cell was prepared and evaluated in the same manner as in Example 21 except that the gel electrolyte was adjusted so that the organic compound represented by Chemical Formula 2 was 0.05% by mass.

(Example 28)
A cell was prepared and evaluated in the same manner as in Example 21 except that the gel electrolyte was adjusted so that the VC was 0.5% by mass and the organic compound represented by Chemical Formula 2 was 0.1% by mass.

(Example 29)
A cell was prepared and evaluated in the same manner as in Example 21 except that the gel electrolyte was adjusted so that the VC was 3.0% by mass and the organic compound represented by Chemical Formula 2 was 0.1% by mass.

(Example 30)
A cell was prepared and evaluated in the same manner as in Example 21 except that the negative electrode material was massive graphite.

(Example 31)
A cell was prepared and evaluated in the same manner as in Example 25 except that the negative electrode material was massive graphite.

(Comparative Example 9)
A cell was prepared and evaluated in the same manner as in Example 21 except that the gel electrolyte was adjusted so that the organic compound represented by Chemical Formula 2 was 0% by mass.

(Comparative Example 10)
A cell was prepared and evaluated in the same manner as in Example 21 except that the gel electrolyte was adjusted so that the organic compound represented by Chemical Formula 2 was 6.0% by mass.

(Comparative Example 11)
A cell was prepared and evaluated in the same manner as in Example 21 except that the gel electrolyte was adjusted so that the organic compound represented by Chemical Formula 2 was 8.0% by mass.

(Comparative Example 12)
A cell was prepared and evaluated in the same manner as in Example 21 except that the gel electrolyte was adjusted so that the VC was 3.0% by mass and the organic compound represented by Chemical Formula 2 was 0% by mass.

(Comparative Example 13)
A cell was prepared and evaluated in the same manner as in Comparative Example 10 except that the negative electrode material was massive graphite.

(Comparative Example 14)
A cell was prepared and evaluated in the same manner as in Comparative Example 11 except that the negative electrode material was massive graphite.

(Comparative Example 15)
A cell was prepared and evaluated in the same manner as in Comparative Example 12 except that the negative electrode material was massive graphite.

  Table 6 shows the rate characteristics, capacity retention rate in the cycle test, and cell volume change rate for Examples 21 to 31 and Comparative Examples 9 to 15, and Table 7 shows the results of the 45 ° C. storage test evaluation.

  In the lithium polymer battery of the present invention, as shown in Examples 21 to 27 of Tables 6 and 7, when the concentration of the organic compound represented by Chemical Formula 2 is 0.05 or more and 5.0% by mass or less, rate characteristics, etc. It was found that the characteristics of the organic compound represented by Chemical Formula 2 were clearly better than those of Comparative Examples 9 to 11 to which other concentrations were added.

  From Example 28 and Example 29, by adding VC to the organic compound represented by Chemical Formula 2, the amount of additive is at least as high as that of using the organic compound represented by Chemical Formula 2 alone. It was revealed.

 Moreover, the same tendency is seen in any of the cases where massive graphite, which is said to have good characteristics (Examples 30 and 31, Comparative Examples 13 to 15), and when scale-like graphite is used, is represented by the chemical formula 2 As in the case where Mn is used for the positive electrode, it has been clarified that the compound exhibits good characteristics even in flake graphite, which has been conventionally unsuitable for a battery using a gel electrolyte.

(Example 32)
A cell was prepared and evaluated in the same manner as in Example 21 except that the organic compound represented by Chemical formula 3 was used instead of the organic compound represented by Chemical formula 2.

(Example 33)
A cell was prepared and evaluated in the same manner as in Example 22 except that the organic compound represented by Chemical formula 3 was used instead of the organic compound represented by Chemical formula 2.

(Example 34)
A cell was prepared and evaluated in the same manner as in Example 23 except that the organic compound represented by Chemical Formula 3 was used instead of the organic compound represented by Chemical Formula 2.

(Example 35)
A cell was prepared and evaluated in the same manner as in Example 24 except that the organic compound represented by Chemical formula 3 was used instead of the organic compound represented by Chemical formula 2.

(Example 36)
A cell was prepared and evaluated in the same manner as in Example 25 except that the organic compound represented by the chemical formula 3 was used instead of the organic compound represented by the chemical formula 2.

(Example 37)
A cell was prepared and evaluated in the same manner as in Example 26 except that the organic compound represented by Chemical formula 3 was used instead of the organic compound represented by Chemical formula 2.

(Example 38)
A cell was prepared and evaluated in the same manner as in Example 27 except that the organic compound represented by Chemical Formula 3 was used instead of the organic compound represented by Chemical Formula 2.

(Example 39)
A cell was prepared and evaluated in the same manner as in Example 28 except that the organic compound represented by Chemical Formula 3 was used instead of the organic compound represented by Chemical Formula 2.

(Example 40)
A cell was prepared and evaluated in the same manner as in Example 29 except that the organic compound represented by Chemical Formula 3 was used instead of the organic compound represented by Chemical Formula 2.

(Example 41)
A cell was prepared and evaluated in the same manner as in Example 30 except that the organic compound represented by Chemical Formula 3 was used instead of the organic compound represented by Chemical Formula 2.

(Example 42)
A cell was prepared and evaluated in the same manner as in Example 31 except that the organic compound represented by Chemical Formula 3 was used instead of the organic compound represented by Chemical Formula 2.

(Comparative Example 16)
A cell was prepared and evaluated in the same manner as in Example 32 except that the gel electrolyte was adjusted so that the organic compound represented by Chemical Formula 2 was 0% by mass.

(Comparative Example 17)
A cell was prepared and evaluated in the same manner as in Comparative Example 10 except that the organic compound represented by Chemical Formula 3 was used instead of the organic compound represented by Chemical Formula 2.

(Comparative Example 18)
A cell was prepared and evaluated in the same manner as in Comparative Example 11 except that the organic compound represented by Chemical Formula 3 was used instead of the organic compound represented by Chemical Formula 2.

(Comparative Example 19)
A cell was prepared and evaluated in the same manner as in Comparative Example 17 except that massive graphite was used as the negative electrode material.

(Comparative Example 20)
A cell was prepared and evaluated in the same manner as in Comparative Example 18 except that massive graphite was used as the negative electrode material.

  Table 8 shows the rate characteristics, capacity retention rate in the cycle test, and cell volume change rate for Examples 32-42 and Comparative Examples 16-20, and Table 9 shows the results of the 45 ° C. storage test evaluation.

  In the lithium polymer battery of the present invention, when the concentration of the organic compound represented by Chemical Formula 3 is 0.05 or more and 5.0% by mass or less as shown in Examples 32-38 of Tables 8 and 9, the rate characteristics and the like are changed. It was found that the characteristics of the organic compound represented by 3 were clearly better than those of Comparative Examples 16 to 18 to which other concentrations were added.

  In addition, the same tendency is observed in the case where massive graphite, which is said to have good characteristics (Examples 41 and 42, Comparative Examples 19 and 20), and in the case where flaky graphite is used, and the organic compound represented by Chemical Formula 3 is used. As in the case where Mn is used for the positive electrode, it has been clarified that the compound exhibits good characteristics even in flake graphite, which has been conventionally unsuitable for a battery using a gel electrolyte.

(Example 43)
A cell was prepared and evaluated in the same manner as in Example 1 except that the packing density of the positive electrode was changed to 2.7 g / cm ³ .

(Example 44)
A cell was prepared and evaluated in the same manner as in Example 1 except that the packing density of the positive electrode was 2.6 g / cm ³ .

(Example 45)
A cell was prepared and evaluated in the same manner as in Example 1 except that the packing density of the positive electrode was 2.5 g / cm ³ .

(Example 46)
A cell was prepared and evaluated in the same manner as in Example 1 except that the packing density of the positive electrode was changed to 2.9 g / cm ³ .

(Example 47)
A cell was prepared and evaluated in the same manner as in Example 1 except that the packing density of the positive electrode was 3.0 g / cm ³ .

(Comparative Example 21)
A lithium polymer battery was prepared and evaluated in the same manner as in Example 1 except that the packing density of the positive electrode was 2.4 g / cm ³ .

(Comparative Example 22)
A lithium polymer battery was prepared and evaluated in the same manner as in Example 1 except that the packing density of the positive electrode was 3.1 g / cm ³ .

  Table 10 shows the rate characteristics for Examples 1 and 43 to 47 and Comparative Examples 21 and 22 and the capacity retention ratio in the cycle test.

In the lithium polymer battery of the present invention, as shown in Examples 1 and 43 to 47 in Table 10, when lithium manganate was used as the positive electrode active material, the positive electrode filling density was 2.5 g / cm ³ or more 3 In the case of 0.0 g / cm ³ or less, it was found that the characteristics were clearly better than those of Comparative Example 21 and Comparative Example 22 in which the electrode density was lower or higher in rate characteristics and the like.

(Example 48)
A cell was prepared and evaluated in the same manner as in Example 21 except that the packing density of the positive electrode was 3.5 g / cm ³ .

(Example 49)
A cell was prepared and evaluated in the same manner as in Example 21 except that the packing density of the positive electrode was changed to 3.4 g / cm ³ .

(Example 50)
A cell was prepared and evaluated in the same manner as in Example 21 except that the packing density of the positive electrode was changed to 3.3 g / cm ³ .

(Example 51)
A cell was prepared and evaluated in the same manner as in Example 21 except that the packing density of the positive electrode was 3.7 g / cm ³ .

(Example 52)
A cell was prepared and evaluated in the same manner as in Example 21 except that the packing density of the positive electrode was 3.8 g / cm ³ .

(Comparative Example 23)
A cell was prepared and evaluated in the same manner as in Example 1 except that the packing density of the positive electrode was 3.2 g / cm ³ .

(Comparative Example 24)
A cell was prepared and evaluated in the same manner as in Example 1 except that the packing density of the positive electrode was changed to 3.9 g / cm ³ .

  Table 11 shows the rate characteristics of Examples 21 and 48 to 52 and Comparative Examples 23 and 24 and the capacity retention ratio in the cycle test.

In the lithium polymer battery of the present invention, as shown in Examples 21 and 48 to 52 of Table 11, when lithium cobaltate was used as the positive electrode active material, the packing density of the positive electrode was 3.3 g / cm ³ or more 3 In the case of 0.8 g / cm ³ or less, it was found that the characteristics were clearly better than those of Comparative Example 23 and Comparative Example 24 in which the positive electrode packing density exceeded the range in rate characteristics and the like.

The figure explaining the structure of the positive electrode of the lithium polymer battery of this invention. The figure explaining the structure of the negative electrode of the lithium polymer battery of this invention. Sectional drawing explaining the structure of the battery element after winding of the lithium polymer battery of this invention. The figure explaining the exterior | packing process of the lithium polymer battery of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Positive electrode 2 Al foil 3 Positive electrode active material application part 4 Positive electrode active material non-application part 5 Positive electrode active material single side application part 6 Positive electrode conductive tab
7 Negative electrode 8 Cu foil 9 Negative electrode active material application part 10 Negative electrode active material one-side application part 11 Negative electrode active material non-application part 12 Negative electrode conductive tab 13 Separator 14 Cell

Claims (14)

A lithium polymer battery comprising at least a positive electrode, a negative electrode, a separator, and a gel electrolyte, wherein the gel electrolyte contains a solvent, a crosslinked polymer, and an organic compound represented by chemical formula 1 Z is a halogen atom, a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, a polyfluoroalkyl group, or a substituted or unsubstituted cyclic hydrocarbon having 4 to 20 carbon atoms, or XR ₅ (where X is Represents an oxygen atom, a sulfur atom or NR ₆ , R ₆ represents a hydrogen atom or a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, and R ₅ represents a substituted or unsubstituted cyclic hydrocarbon having 4 to 20 carbon atoms. Represents). n represents an integer of 0 to 4. A ₁ and A ₂ are each independently an oxygen atom, a sulfur atom, or A ₁ is NR ₇ and A ₂ is NR ₈ (where R ₇ and R ₈ are each independently a hydrogen atom, a halogen atom, a substituted or unsubstituted atom) Represents an alkyl group having 1 to 10 carbon atoms, a polyfluoroalkyl group having 1 to 10 carbon atoms, or a substituted or unsubstituted cyclic hydrocarbon having 4 to 20 carbon atoms, and R ₇ and R ₈ are bonded to each other. A ring structure may be formed). L represents a methylene group or a single bond. M represents boron or phosphorus. B ₁ and B ₂ each independently represent a carbonyl group, a substituted or unsubstituted alkylene group or a polyfluoroalkylene group. m represents an integer of 1 to 3 (provided that 2m + n = 4 when M is boron and 2m + n = 6 when M is phosphorus)].

2. The lithium polymer according to claim 1, wherein the positive electrode has lithium manganate as a main component as an active material, and a filling density of the positive electrode is 2.5 g / cm ³ or more and 3.0 g / cm ³ or less. battery. The positive electrode is mainly composed of lithium cobaltate as an active material, the filling density of the positive electrode 3.3 g / cm ³ or more, the lithium polymer according to claim 1, characterized in that 3.8 g / cm ³ or less battery.   The lithium polymer battery according to any one of claims 1 to 3, which has a peak indicating that boron and oxygen are present in a depth direction of 0.1 to 1.0 µm in SIMS measurement of the surface of the negative electrode. .   The lithium polymer battery according to claim 4, wherein a peak of boron and oxygen in the SIMS measurement includes a decomposition product of an organic compound represented by the chemical formula (1).   The lithium polymer battery according to any one of claims 1 to 5, wherein the minimum orbital energy (LUMO) of the organic compound represented by the chemical formula 1 is -1.5 (eV) or more and 0 (eV) or less.   The gel electrolyte contains a solvent, a crosslinked polymer, 0.1 to 3.0% by mass of vinylene carbonate or a derivative thereof, and 0.05 to 5.0% by mass of an organic compound represented by Chemical formula 1. The lithium polymer battery according to any one of -6. The lithium polymer battery according to any one of claims 1 to 7, wherein the organic compound represented by Chemical Formula 1 is an organic compound represented by Chemical Formula 2 or Chemical Formula 3.

  The positive electrode contains lithium cobaltate, and the gel electrolyte contains a solvent containing vinylene carbonate or a derivative thereof, a cross-linked polymer, and an organic compound represented by 0.05 to 5.0% by mass of Chemical Formula 1. Item 9. The lithium polymer battery according to any one of Items 1 to 8.   The positive electrode contains lithium manganate, and the gel electrolyte contains a solvent containing vinylene carbonate or a derivative thereof, a crosslinked polymer, and an organic compound represented by 0.05 to 5.0% by mass of Chemical Formula 1. Item 9. The lithium polymer battery according to any one of Items 1 to 8.   The lithium polymer battery according to claim 1, wherein the cross-linked polymer is composed of an acrylic polymer.   The lithium polymer battery according to claim 1, wherein the solvent contains at least a chain carbonate and a cyclic carbonate.   The lithium polymer battery according to any one of claims 1 to 12, wherein the negative electrode contains graphite as an active material.   The lithium polymer battery according to claim 1, wherein the lithium polymer battery is packaged with a laminate material.

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