JP2019145409A - Lithium ion secondary battery - Google Patents

Abstract

To provide a lithium ion secondary battery capable of improving self-discharge characteristics.SOLUTION: A lithium ion secondary battery includes a positive electrode, a negative electrode, a separator located between the positive electrode and the negative electrode, an electrolyte solution, and the negative electrode includes a negative electrode active material layer on a negative electrode current collector, and the negative electrode active material layer includes any one selected from sodium or a sodium compound, and the electrolyte includes a carboxylic acid ester.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a lithium ion secondary battery.

  In recent years, a lithium ion secondary battery used as a main power source for mobile communication devices and portable electronic devices has a feature of high electromotive force and high energy density.

  In a lithium ion secondary battery using a carbon-based negative electrode, during the first charge / discharge, carbonates that are constituent components of the electrolytic solution are reduced and decomposed on the surface of the negative electrode active material, and a film called SEI (Solid electrolyte interface) is formed. It is known to form. Since the decomposition of the solvent on the negative electrode active material surface is suppressed after the formation of the SEI film, the battery life can be extended.

  However, the life of the battery is greatly influenced by the state of the SEI film, and when a non-uniform film is formed, there is a problem that the self-discharge characteristics deteriorate.

  Therefore, Patent Document 1 reports that when a negative electrode is formed by adding anatase-type titanium oxide to a lithium titanium composite oxide as a negative electrode active material, the self-discharge reaction of the negative electrode can be suppressed.

JP2013-178916A

  However, the conventional methods still do not satisfy the various characteristics, and further improvement of the self-discharge characteristics is demanded.

  The present invention has been made in view of the above-described problems of the prior art, and an object thereof is to provide a lithium ion secondary battery capable of improving self-discharge characteristics.

  In order to solve the above problems, a lithium ion secondary battery according to the present invention is a lithium ion secondary battery comprising a positive electrode, a negative electrode, a separator positioned between the positive electrode and the negative electrode, and an electrolytic solution. The negative electrode has a negative electrode active material layer on a negative electrode current collector, the negative electrode active material layer includes any one selected from sodium or a sodium compound, and the electrolyte includes a carboxylic acid ester. And

  Since the carboxylic acid ester has a low viscosity and a high wettability, the electrolyte can be uniformly permeated into the deep part of the electrode. Furthermore, by using a negative electrode containing sodium having a higher oxidation-reduction potential than lithium, the SEI film forming reaction is performed prior to lithium. Further, since the SEI film contains sodium having a large ionic radius, the ion conduction path of lithium ions can be inhibited, and the self-discharge characteristics are improved. In particular, when sodium is present in the negative electrode, a film containing sodium can also be formed inside the negative electrode, so that high self-discharge characteristics can be obtained.

  In the lithium ion secondary battery according to the present invention, it is preferable that any one selected from the above sodium or sodium compound is contained in an amount of 0.05 to 0.5% by mass in terms of sodium with respect to the negative electrode active material layer.

  According to this, the addition amount of sodium is an appropriate amount, and the self-discharge characteristics are further improved.

  In the lithium ion secondary battery according to the present invention, it is preferable that the sodium compound further includes at least one selected from sodium acetate, sodium propionate, and sodium butyrate.

  According to this, it is suitable as sodium and the self-discharge characteristic is further improved.

  In the lithium ion secondary battery according to the present invention, it is preferable that the carboxylic acid ester further includes at least one selected from propionic acid ester or acetic acid ester.

  According to this, it is suitable as a carboxylic acid ester, and the self-discharge characteristics are further improved.

In the lithium ion secondary battery according to the present invention, the carboxylic acid ester is preferably represented by the following chemical formula (1).
(Here, R ₁ and R ₂ are linear or branched alkyl groups or substituted alkyl groups having 1 to 4 carbon atoms, and the total number of carbon atoms of R ₁ and R ₂ is 5 or less.)

  According to this, it is suitable as a carboxylic acid ester, and the self-discharge characteristics are further improved.

  In the lithium ion secondary battery according to the present invention, the carboxylic acid ester is preferably contained in the electrolytic solution in an amount of 50% by volume to 90% by volume.

  According to this, it is suitable as a composition of carboxylic acid ester, and the self-discharge characteristic is further improved.

  ADVANTAGE OF THE INVENTION According to this invention, the lithium ion secondary battery which can improve a self-discharge characteristic is provided.

It is a schematic cross section of the lithium ion secondary battery of this embodiment.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments according to the invention will be described with reference to the drawings. In addition, this invention is not limited to the following embodiment. The constituent elements described below include those that can be easily conceived by those skilled in the art and those that are substantially the same. Furthermore, the constituent elements described below can be appropriately combined.

<Lithium ion secondary battery>
As shown in FIG. 1, a lithium ion secondary battery 100 according to the present embodiment is disposed adjacent to each other between a plate-like negative electrode 20 and a plate-like positive electrode 10 facing each other, and the negative electrode 20 and the positive electrode 10. A plate-like separator 18, an electrolyte solution containing lithium ions, a case 50 containing these in a sealed state, and one end of the negative electrode 20 being electrically connected. A lead 62 whose other end protrudes outside the case and a lead 60 whose one end is electrically connected to the positive electrode 10 and whose other end protrudes outside the case are provided.

  The positive electrode 10 includes a positive electrode current collector 12 and a positive electrode active material layer 14 formed on the positive electrode current collector 12. The negative electrode 20 includes a negative electrode current collector 22 and a negative electrode active material layer 24 formed on the negative electrode current collector 22. The separator 18 is located between the negative electrode active material layer 24 and the positive electrode active material layer 14.

<Positive electrode>
(Positive electrode current collector)
The positive electrode current collector 12 may be a conductive plate material, and for example, a metal thin plate (metal foil) such as aluminum, an alloy thereof, or stainless steel can be used.

(Positive electrode active material layer)
The positive electrode active material layer 14 is mainly composed of a positive electrode active material, a positive electrode binder, and a positive electrode conductive additive.

(Positive electrode active material)
As the positive electrode active material, lithium ion occlusion and release, lithium ion desorption and insertion (intercalation), or doping and dedoping of a counter anion (for example, PF ₆ ⁻ ) of the lithium ion are reversibly performed. If it can be made to advance, it will not specifically limit, A well-known electrode active material can be used. For example, lithium cobaltate (LiCoO ₂ ), lithium nickelate (LiNiO ₂ ), lithium manganese spinel (LiMn ₂ O ₄ ), and chemical formula: LiNixCoyMnzMaO ₂ (x + y + z + a = 1, 0 ≦ x ≦ 1, 0 ≦ y ≦ 1 , 0 ≦ z ≦ 1, 0 ≦ a ≦ 1, M is one or more elements selected from Al, Mg, Nb, Ti, Cu, Zn, and Cr), a lithium vanadium compound Lia (M) b (PO ₄ ) c (where M = VO or V, and 0.9 ≦ a ≦ 3.3, 0.9 ≦ b ≦ 2.2, 0.9 ≦ c ≦ 3.3) Olivine type LiMPO ₄ (where M represents one or more elements selected from Co, Ni, Mn, Fe, Mg, Nb, Ti, Al, and Zr or VO), lithium titanate (Li ₄ Ti ₅ O _{1 2} ), composite metal oxides such as LiNixCoyAlzO ₂ (0.9 <x + y + z <1.1).

When a lithium vanadium compound is used among the positive electrode active materials, when combined with the negative electrode and the electrolytic solution according to the present embodiment, an effect of improving self-discharge characteristics is strongly obtained. Among the lithium vanadium compounds, particularly the effect of improving the self-discharge characteristics can be obtained more strongly with LiVOPO ₄ . Although the exact mechanism of the above action is still unclear, it is presumed that vanadium ions are complexed with carboxylic acid esters to form a film on the negative electrode.

(Binder for positive electrode)
The positive electrode binder bonds the positive electrode active materials to each other and bonds the positive electrode active material layer 14 and the positive electrode current collector 12. The binder is not particularly limited as long as it can be bonded as described above. For example, fluorine resin such as polyvinylidene fluoride (PVDF) and polytetrafluoroethylene (PTFE), cellulose, styrene / butadiene rubber, ethylene / propylene rubber, polyimide A resin, a polyamideimide resin, or the like may be used. Alternatively, an electron conductive conductive polymer or an ion conductive conductive polymer may be used as the binder. Examples of the electron conductive conductive polymer include polyacetylene, polythiophene, and polyaniline. Examples of the ion conductive conductive polymer include those obtained by combining a polyether polymer compound such as polyethylene oxide and polypropylene oxide and a lithium salt such as LiClO ₄ , LiBF ₄ , and LiPF _6. It is done.

  Although content of the binder in the positive electrode active material layer 14 is not specifically limited, When adding, it is preferable that it is 0.5-5 mass parts with respect to the mass of a positive electrode active material.

(Conductive aid for positive electrode)
The conductive auxiliary agent for positive electrode is not particularly limited as long as it improves the conductivity of the positive electrode active material layer 14, and a known conductive auxiliary agent can be used. Examples thereof include carbon-based materials such as graphite and carbon black, metal fine powders such as copper, nickel, stainless steel, and iron, and conductive oxides such as ITO.

<Negative electrode>
The negative electrode 20 according to this embodiment includes a negative electrode active material layer 24 on a negative electrode current collector 22.

(Negative electrode active material layer)
The negative electrode active material layer 24 is mainly composed of a negative electrode active material, a negative electrode binder, and a negative electrode conductive additive.

  The negative electrode active material layer 24 according to this embodiment includes one selected from sodium or a sodium compound.

  According to this, the SEI film forming reaction is performed prior to lithium by using a negative electrode containing any one selected from sodium or a sodium compound having a higher oxidation-reduction potential than lithium. Further, since the SEI film contains sodium having a large ionic radius, the ion conduction path of lithium ions can be inhibited, and the self-discharge characteristics are improved. In particular, when sodium is present in the negative electrode, a film containing sodium can also be formed inside the negative electrode, so that high self-discharge characteristics can be obtained.

  It is more preferable that the negative electrode active material layer according to the present embodiment further includes 0.05 to 0.5% by mass of any one selected from the above sodium or sodium compound in terms of sodium with respect to the negative electrode active material layer.

  According to this, the addition amount of sodium is an appropriate amount, and the self-discharge characteristics are further improved.

  In the negative electrode active material layer according to this embodiment, it is preferable that the sodium compound further includes at least one selected from sodium acetate, sodium propionate, and sodium butyrate.

According to this, it is suitable as a sodium compound, and the self-discharge characteristic is further improved.
(Negative electrode current collector)
The negative electrode current collector 22 may be a conductive plate material, and for example, a metal thin plate (metal foil) such as copper can be used.

(Negative electrode active material)
The negative electrode active material is not particularly limited as long as it can reversibly advance occlusion and release of lithium ions and desorption and insertion (intercalation) of lithium ions, and a known electrode active material can be used. . For example, carbon materials such as graphite and hard carbon, silicon materials such as silicon oxide (SiO _x ) metal silicon (Si), metal oxides such as lithium titanate (LTO), metal materials such as lithium, tin, and zinc Is mentioned.

  When a metal material is not used as the negative electrode active material, the negative electrode active material layer 24 may further include a negative electrode binder and a negative electrode conductive additive.

(Binder for negative electrode)
There is no limitation in particular as a binder for negative electrodes, The thing similar to the binder for positive electrodes described above can be used.

(Conductive aid for negative electrode)
There is no limitation in particular as a conductive support agent for negative electrodes, The thing similar to the conductive support agent for positive electrodes described above can be used.

<Electrolyte>
The electrolytic solution according to the present embodiment contains a carboxylic acid ester.

  According to this, since the carboxylic acid ester has a low viscosity and a high wettability, the electrolytic solution can be uniformly penetrated to the deep part of the electrode, and the self-discharge characteristics are improved.

  In the electrolytic solution according to this embodiment, the carboxylic acid ester is preferably represented by the chemical formula (1), and preferably includes at least one selected from propionic acid ester or acetic acid ester.

  According to this, it is suitable as a carboxylic acid ester, and the self-discharge characteristics are further improved.

  In the electrolytic solution according to this embodiment, the carboxylic acid ester is preferably contained in the electrolytic solution in an amount of 50% by volume to 90% by volume.

  According to this, it is suitable as a composition of carboxylic acid ester, and the self-discharge characteristic is further improved. Moreover, when 50 volume% or more of carboxylic acid ester is contained, the viscosity of electrolyte solution is fully reduced and the effect of viscosity reduction can be acquired to the maximum.

(Other solvents)
In addition to the carboxylic acid ester, a solvent that is generally used for lithium ion secondary batteries can be used for the electrolytic solution according to the present embodiment. The solvent is not particularly limited. For example, cyclic carbonate compounds such as ethylene carbonate (EC) and propylene carbonate (PC), chain carbonate compounds such as diethyl carbonate (DEC) and ethyl methyl carbonate (EMC), and the like are arbitrarily selected. It can be used by mixing at a ratio of

(Electrolytes)
The electrolyte is not particularly limited as long as it is a lithium salt used as an electrolyte of a lithium ion secondary battery. For example, inorganic acid anion salts such as LiPF ₆ , LiBF ₄ , lithium bisoxalate borate, LiCF ₃ SO ₃ , An organic acid anion salt such as (CF ₃ SO ₂ ) ₂ NLi, (FSO ₂ ) ₂ NLi, or the like can be used.

  As mentioned above, although preferred embodiment which concerns on this invention was described, this invention is not limited to the said embodiment.

  EXAMPLES Hereinafter, although this invention is demonstrated more concretely based on an Example and a comparative example, this invention is not limited to a following example.

[Example 1]
(Preparation of positive electrode)
50 parts by mass of LiVOPO _4, 35 parts by mass of Li (Ni _0.80 Co _0.15 Al _0.05 ) O ₂ , 5 parts by mass of carbon black, and 10 parts by mass of PVDF are dispersed in N-methyl-2-pyrrolidone (NMP). Then, a slurry for forming the positive electrode active material layer was prepared. This slurry was applied to one surface of an aluminum metal foil having a thickness of 20 μm so that the applied amount of the positive electrode active material was 9.0 mg / cm ² and dried at 100 ° C. to form a positive electrode active material layer. Then, it pressure-molded with the roller press and produced the positive electrode.

(Preparation of negative electrode)
90 parts by mass of natural graphite, 5 parts by mass of carbon black, and 5 parts by mass of PVDF were dispersed in N-methyl-2-pyrrolidone (NMP) to prepare a slurry for forming a negative electrode active material layer. Thereafter, sodium acetate as a sodium source was added to the slurry so that the sodium content was 0.01% by mass. The slurry was applied to one surface of a copper foil having a thickness of 20 μm so that the amount of the negative electrode active material applied was 6.0 mg / cm ² and dried at 100 ° C. to form a negative electrode active material layer. Then, it pressure-molded with the roller press and produced the negative electrode.

  When the sodium content of the negative electrode active material layer produced above was examined, it was confirmed that the prepared amount of sodium was contained.

  Moreover, the sodium contained in the produced negative electrode active material layer was sodium acetate.

(Preparation of electrolyte)
Using methyl propionate as a carboxylic acid ester and adjusting the volume ratio to EC / methyl propionate = 30: 70, LiPF ₆ was dissolved to a concentration of 1 mol / L, and an electrolyte solution was obtained. Was made.

(Production of evaluation lithium-ion secondary battery)
The positive electrode and negative electrode produced above and a separator made of a polyethylene microporous film were sandwiched between them to be put in an aluminum laminate pack. After injecting the electrolytic solution prepared above into this aluminum laminate pack, vacuum sealing was performed to prepare a lithium ion secondary battery for evaluation.

(Measurement of self-discharge characteristics)
About the lithium ion secondary battery for evaluation produced above, using a secondary battery charge / discharge test apparatus (manufactured by Hokuto Denko Co., Ltd.), a charge rate of 1.0 C (at constant current charge at 25 ° C. in 1 hour The battery was charged until the battery voltage reached 4.2 V by constant current charging (current value at which charging was completed). After the completion of charging, the voltage after standing for 24 hours at room temperature was set to V1, and then the voltage after standing for 5 days in a 40 ° C. environment was set to V2. Self-discharge characteristics were determined from the following values (1) from the obtained values of V1 and V2. The results are shown in Table 1 as self-discharge characteristics.
Self-discharge characteristic (mV / day) = V1-V2 (1)

[Example 2]
A lithium ion secondary battery for evaluation of Example 2 was produced in the same manner as in Example 1 except that the addition amount of the sodium source used in the production of the negative electrode was changed as shown in Table 1.

[Example 3]
A lithium ion secondary battery for evaluation of Example 3 was produced in the same manner as in Example 1 except that the addition amount of the sodium source used in the production of the negative electrode was changed as shown in Table 1.

[Example 4]
A lithium ion secondary battery for evaluation of Example 4 was produced in the same manner as in Example 1 except that the amount of sodium source used in the production of the negative electrode was changed as shown in Table 1.

[Example 5]
A lithium ion secondary battery for evaluation of Example 5 was produced in the same manner as in Example 1 except that the addition amount of the sodium source used in the production of the negative electrode was changed as shown in Table 1.

[Example 6]
A lithium ion secondary battery for evaluation of Example 6 was produced in the same manner as in Example 1 except that the addition amount of the sodium source used in the production of the negative electrode was changed as shown in Table 1.

[Example 7]
A lithium ion secondary battery for evaluation of Example 7 was produced in the same manner as in Example 1 except that the addition amount of the sodium source used in the production of the negative electrode was changed as shown in Table 1.

[Example 8]
A lithium ion secondary battery for evaluation of Example 8 was produced in the same manner as in Example 3 except that the sodium source used in the production of the negative electrode was changed as shown in Table 1.

[Example 9]
A lithium ion secondary battery for evaluation of Example 9 was produced in the same manner as in Example 3 except that the sodium source used in the production of the negative electrode was changed as shown in Table 1.

[Example 10]
A lithium ion secondary battery for evaluation of Example 10 was produced in the same manner as in Example 3 except that the sodium source used in the production of the negative electrode was changed as shown in Table 1.

[Example 11]
A lithium ion secondary battery for evaluation of Example 11 was produced in the same manner as in Example 3 except that the composition of the electrolytic solution was changed as shown in Table 1.

[Example 12]
A lithium ion secondary battery for evaluation of Example 12 was produced in the same manner as in Example 3 except that the composition of the electrolytic solution was changed as shown in Table 1.

[Example 13]
A lithium ion secondary battery for evaluation of Example 13 was produced in the same manner as in Example 3 except that the composition of the electrolytic solution was changed as shown in Table 1.

[Example 14]
A lithium ion secondary battery for evaluation of Example 14 was produced in the same manner as Example 3 except that the composition of the electrolytic solution was changed as shown in Table 1.

[Example 15]
A lithium ion secondary battery for evaluation of Example 15 was produced in the same manner as in Example 3 except that the carboxylic acid ester used in the production of the electrolytic solution was changed as shown in Table 1.

[Example 16]
A lithium ion secondary battery for evaluation of Example 16 was produced in the same manner as in Example 3 except that the carboxylic acid ester used in the production of the electrolytic solution was changed as shown in Table 1.

[Example 17]
A lithium ion secondary battery for evaluation of Example 17 was produced in the same manner as in Example 3 except that the carboxylic acid ester used in the production of the electrolytic solution was changed as shown in Table 1.

[Example 18]
A lithium ion secondary battery for evaluation of Example 18 was produced in the same manner as in Example 3 except that the composition of the carboxylic acid ester used in the production of the electrolytic solution and the composition of the electrolytic solution was changed as shown in Table 1.

[Example 19]
A lithium ion secondary battery for evaluation of Example 19 was produced in the same manner as in Example 3 except that the composition of the carboxylic acid ester used in the production of the electrolytic solution and the composition of the electrolytic solution was changed as shown in Table 1.

[Example 20]
A lithium ion secondary battery for evaluation of Example 20 was produced in the same manner as in Example 3 except that the composition of the carboxylic acid ester used in the production of the electrolytic solution and the composition of the electrolytic solution was changed as shown in Table 1.

[Example 21]
A lithium ion secondary battery for evaluation of Example 21 was produced in the same manner as in Example 3 except that the composition of the carboxylic acid ester used in the production of the electrolytic solution and the composition of the electrolytic solution was changed as shown in Table 1.

[Example 22]
A lithium ion secondary battery for evaluation of Example 22 was produced in the same manner as in Example 3 except that the carboxylic acid ester used in the production of the electrolytic solution was changed as shown in Table 1.

[Example 23]
A lithium ion secondary battery for evaluation of Example 23 was produced in the same manner as in Example 3 except that the carboxylic acid ester used in the production of the electrolytic solution was changed as shown in Table 1.

[Example 24]
A lithium ion secondary battery for evaluation of Example 24 was produced in the same manner as in Example 3 except that the carboxylic acid ester used in the production of the electrolytic solution was changed as shown in Table 1.

[Example 25]
A lithium ion secondary battery for evaluation of Example 25 was produced in the same manner as in Example 3 except that the carboxylic acid ester used in the production of the electrolytic solution was changed as shown in Table 1.

[Example 26]
A lithium ion secondary battery for evaluation of Example 26 was produced in the same manner as in Example 3 except that the carboxylic acid ester used in the production of the electrolytic solution was changed as shown in Table 1.

[Example 27]
A lithium ion secondary battery for evaluation of Example 27 was produced in the same manner as in Example 3 except that the carboxylic acid ester used in the production of the electrolytic solution was changed as shown in Table 1.

[Example 28]
A lithium ion secondary battery for evaluation of Example 28 was produced in the same manner as in Example 3 except that the carboxylic acid ester used in the production of the electrolytic solution was changed as shown in Table 1.

[Example 29]
A lithium ion secondary battery for evaluation of Example 29 was produced in the same manner as in Example 3 except that the composition of the electrolytic solution was changed as shown in Table 1.

[Comparative Example 1]
A lithium ion secondary battery for evaluation of Comparative Example 1 was prepared in the same manner as in Example 3 except that the carboxylic acid ester was not added in the preparation of the electrolytic solution and the composition of the electrolytic solution was changed as shown in Table 1.

[Comparative Example 2]
A lithium ion secondary battery for evaluation of Comparative Example 2 was produced in the same manner as in Example 3 except that the carboxylic acid ester was not added in the production of the electrolytic solution and the composition of the electrolytic solution was changed as shown in Table 1.

[Comparative Example 3]
A lithium ion secondary battery for evaluation of Comparative Example 3 was produced in the same manner as Example 3 except that the sodium source was not added in the production of the negative electrode.

  When the sodium content of Examples 2 to 29 and Comparative Examples 1 and 2 was examined in the same manner as in Example 1, it was confirmed that the amount was the same as the charged amount.

  Moreover, when sodium of the negative electrode produced similarly was analyzed, it confirmed that it was a sodium source of Table 1.

  About the evaluation lithium ion secondary battery produced in Examples 2-29 and Comparative Examples 1-3, the self-discharge characteristic was measured similarly to Example 1. FIG. The results are shown in Table 1.

In each of Examples 1 to 29, the self-discharge characteristics were improved with respect to Comparative Example 3 in which no sodium source was added.

  From Examples 1 to 7, it was confirmed that the self-discharge characteristics were further improved by setting the ratio of the sodium content in the negative electrode to 0.05 parts by mass or more and 0.5 parts by mass or less.

  From Examples 8 to 10, it was confirmed that the self-discharge characteristics were further improved by using sodium acetate, sodium propionate, and sodium butyrate as the sodium source in the negative electrode.

  In each of Examples 1 to 29, self-discharge characteristics were improved as compared with Comparative Examples 1 and 2 in which no carboxylic acid ester was used.

  From the results of Examples 15 to 17 and Examples 22 to 25, it was confirmed that the effect of further improving the self-discharge characteristics was obtained by setting the total carbon number of the carboxylic acid to 5 or less.

  From the results of Examples 26 to 28, it was confirmed that by using propionic acid or acetate as the carboxylic acid ester, the effect of further improving the self-discharge characteristics was obtained.

  From the results of Examples 11 to 14 and Examples 18 to 21, it was confirmed that the effect of further improving the self-discharge characteristics was obtained by optimizing the composition of the electrolytic solution.

  According to the present invention, a lithium ion secondary battery capable of improving self-discharge characteristics is provided.

  DESCRIPTION OF SYMBOLS 10 ... Positive electrode, 12 ... Positive electrode collector, 14 ... Positive electrode active material layer, 18 ... Separator, 20 ... Negative electrode, 22 ... Negative electrode collector, 24 ... Negative electrode active material layer, 30 ... Laminate, 50 ... Case, 60 62 ... Lead, 100 ... Lithium ion secondary battery.

Claims (6)

A lithium ion secondary battery comprising a positive electrode, a negative electrode, a separator positioned between the positive electrode and the negative electrode, and an electrolyte solution,
The negative electrode has a negative electrode active material layer on a negative electrode current collector,
The lithium ion secondary battery, wherein the negative electrode active material layer includes any one selected from sodium and a sodium compound, and the electrolytic solution includes a carboxylic acid ester.   2. The lithium ion secondary battery according to claim 1, wherein the sodium or the sodium compound is contained in an amount of 0.05 to 0.5 mass% in terms of sodium with respect to the negative electrode active material layer.   The lithium ion secondary battery according to claim 1, wherein the sodium compound includes at least one selected from sodium acetate, sodium propionate, and sodium butyrate.   4. The lithium ion secondary battery according to claim 1, wherein the carboxylic acid ester includes at least one selected from propionic acid esters and acetic acid esters. 5. The lithium ion secondary battery according to any one of claims 1 to 4, wherein the carboxylic acid ester is represented by the following chemical formula (1).
[R1 and R2 are linear or branched alkyl groups or substituted alkyl groups having 1 to 4 carbon atoms. However, the total number of carbon atoms of R1 and R2 is 5 or less]

6. The lithium ion secondary battery according to claim 1, wherein the carboxylic acid ester is contained in the electrolytic solution in an amount of 50% by volume or more and 90% by volume or less.

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