JP4639410B2 - Negative electrode and non-aqueous electrolyte battery - Google Patents

Description

【００８１】
表１から、負極活物質としてＭｇ₂Ｓｉを用いた実施例１と比較例１とを比較し、また、負極活物質としてＳｉ₂Ｎ₂Ｏを用いた実施例２と比較例２とを比較して明らかなように、負極上に導電性高分子を形成した実施例１及び実施例２では、負極上に導電性高分子を形成しなかったた比較例１及び比較例２に比べて、いずれも放電容量維持率が飛躍的に向上していることがわかる。
【００８２】
また、負極上に導電性高分子を形成するばかりでなく、負極中に導電性高分子を混在させた実施例３と比較例１とを比較して明らかなように、実施例３では、比較例１に比べて、高い放電容量維持率が得られていることがわかる。
【００８３】
従って、負極上に導電性高分子を形成し、或いは、負極中に導電性高分子を混在させることで、放電容量維持率を向上できることがわかった。
【００８４】
【発明の効果】
本発明では、Ｍｇ_２Ｓｉや電気化学的にリチウムを４００ｍＡｈ／ｃｍ^３以上でドープ・脱ドープ可能であるＳｉ_２Ｎ_２Ｏと、ポリパラフェニレンとを含有する負極活物質層の表面に、ポリパラフェニレンからなる導電性高分子の膜を被着し、負極活物質層中のポリパラフェニレンの含有量をＭｇ _２ ＳｉやＳｉ _２ Ｎ _２ Ｏの１００重量部に対して、０．１重量部以上、２０重量部以下の範囲とし、導電性高分子の膜厚を、０．０１μｍ以上、５０μｍ以下とすることで、負極中の導電パスを安定に形成するとともに、リチウムのドープ脱ドープに伴う負極の体積変化を抑えた負極を実現することができる。
【００８５】
そして、本発明では、上記のような負極を用いることで、サイクル特性に優れた非水電解質電池を実現することができる。
【図面の簡単な説明】
【図１】本発明に係る非水電解質電池の一構成例を示す断面図である。
【符号の説明】
１ 非水電解液電池、 ２ 負極、 ３ 負極缶、 ４ 正極、 ５ 正極缶、 ６ セパレータ、 ７ 絶縁ガスケット[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a negative electrode and a nonaqueous electrolyte battery using the same.
[0002]
[Prior art]
In recent years, many portable electronic devices such as a camera-integrated video tape recorder, a mobile phone, and a laptop computer have appeared, and their size and weight have been reduced. As a portable power source for these electronic devices, research and development for improving the energy density of batteries, particularly secondary batteries, are being actively promoted. Among them, lithium ion secondary batteries are highly expected because they can obtain a larger energy density than lead batteries and nickel cadmium batteries, which are conventional aqueous electrolyte secondary batteries.
[0003]
As a negative electrode material used for lithium ion batteries, non-graphitizable carbon and carbonaceous materials such as graphite are widely used because they exhibit a relatively high capacity and exhibit good cycle characteristics.
[0004]
[Problems to be solved by the invention]
However, with the recent increase in capacity, further increase in capacity of the negative electrode material has become a problem. In JP-A-8-315825, a high capacity is achieved with a carbonaceous material negative electrode by selecting a carbonized material and production conditions. However, the negative electrode discharge potential was 0.8 V to 1.0 V in terms of lithium potential, the battery discharge voltage when the battery was configured was lowered, and no significant improvement in battery energy density was expected. Furthermore, there is a drawback that the charge / discharge curve has a large hysteresis and the energy efficiency in each charge / discharge cycle is low.
[0005]
On the other hand, as a high load capacity, materials that apply the electrochemical reversible generation / decomposition of certain lithium alloys have been widely studied.
[0006]
High-capacity negative electrodes using Li-Al alloys have been widely studied, and US-Patent Number 4950566 proposes a high-capacity negative electrode using Si alloys. However, the Li—Al alloy or Li—Si alloy expands and contracts with charge / discharge, and the negative electrode is pulverized each time the charge / discharge cycle is repeated, giving a battery with extremely inferior cycle characteristics. In order to improve this cycle characteristic, methods such as adding an element that does not participate in expansion and contraction associated with lithium doping and dedoping into the material have been studied. For example, JP-A-6-325765 discloses Li._xSiO_y(X ≧ 0, 2> y> 0), JP-A-7-230800 discloses Li_xSi_(1-y)M_yO_z(X ≧ 0, 1> y> 0, 0 <z <2) and JP-A-7-288130 propose a Li—Ag—Te alloy.
[0007]
However, even with these methods, the charge / discharge cycle deterioration due to the expansion and contraction of the alloy is large, and the fact that the features of high capacity load are not fully utilized.
[0008]
A high-capacity negative electrode using a group 4B compound other than carbon containing one or more non-metallic elements has been reported in Japanese Patent Application Laid-Open No. 11-102705, but the charge / discharge cycle deterioration is large as in the above case There was a problem.
[0009]
The present invention has been proposed in view of the above-described conventional situation, and provides a negative electrode that suppresses charge / discharge cycle deterioration and realizes a high capacity and a long life, and a nonaqueous electrolyte battery using the negative electrode. For the purpose.
[0010]
[Means for Solving the Problems]
  The negative electrode of the present invention is Mg₂A conductive polymer film made of polyparaphenylene is deposited on the surface of the negative electrode active material layer containing Si and polyparaphenylene, and polyparaphenylene is Mg in the negative electrode active material layer.₂It is contained in the range of 0.1 parts by weight or more and 20 parts by weight or less with respect to 100 parts by weight of Si, and the film thickness of the conductive polymer is 0.01 μm or more and 50 μm or less.Used in non-aqueous electrolyte batteries.
[0011]
  In the negative electrode according to the present invention as described above, Mg₂SiAnd polyparaphenyleneOn the surface of the negative electrode active material containingConsist ofDeposit a conductive polymer film,The content of polyparaphenylene in the negative electrode active material layer is Mg ₂ With respect to 100 parts by weight of Si, the range is 0.1 parts by weight or more and 20 parts by weight or less, and the film thickness of the conductive polymer is 0.01 μm or more and 50 μm or less.By doing so, a conductive path in the negative electrode is stably formed, and a change in volume of the negative electrode due to lithium doping / dedoping is suppressed.
[0012]
  Further, the negative electrode of the present invention electrochemically contains lithium at 400 mAh / cm.³Si that can be doped and dedoped₂N₂A conductive polymer film made of polyparaphenylene is deposited on the surface of the negative electrode active material layer containing O and polyparaphenylene, and polyparaphenylene is Si in the negative electrode active material layer.₂N₂It is contained in the range of 0.1 parts by weight or more and 20 parts by weight or less with respect to 100 parts by weight of O, and the film thickness of the conductive polymer is 0.01 μm or more and 50 μm or less.Used in non-aqueous electrolyte batteries.
[0013]
  In the negative electrode according to the present invention as described aboveIs electrochemically lithium 400 mAh / cm ³ Si that can be doped and dedoped ₂ N ₂ A conductive polymer film made of polyparaphenylene was deposited on the surface of the negative electrode active material layer containing O and polyparaphenylene.,The content of polyparaphenylene in the negative electrode active material layer is changed to Si. ₂ N ₂ With respect to 100 parts by weight of O, the range is 0.1 parts by weight or more and 20 parts by weight or less, and the film thickness of the conductive polymer is 0.01 μm or more and 50 μm or less,A conductive path in the negative electrode is stably formed, and volume change of the negative electrode due to lithium doping / dedoping is suppressed.
[0014]
  The nonaqueous electrolyte battery of the present invention includes a positive electrode containing a lithium composite oxide, Mg₂SiAnd polyparaphenyleneOn the surface of the negative electrode active material layer containingConsist ofConductive polymer film is deposited on the negative electrode and positive electrodeAnd negativeA non-aqueous electrolyte interposed between the electrodes andIn the negative electrode active material layer, polyparaphenylene is Mg ₂ It is contained in the range of 0.1 parts by weight or more and 20 parts by weight or less with respect to 100 parts by weight of Si, and the film thickness of the conductive polymer is 0.01 μm or more and 50 μm or less.
[0015]
  In the non-aqueous electrolyte battery according to the present invention as described above,Mg ₂ A conductive polymer film made of polyparaphenylene is deposited on the surface of a negative electrode active material containing Si and polyparaphenylene, and the content of polyparaphenylene in the negative electrode active material layer is Mg. ₂ With respect to 100 parts by weight of Si, the range is 0.1 parts by weight or more and 20 parts by weight or less, and the film thickness of the conductive polymer is 0.01 μm or more and 50 μm or less,A conductive path in the negative electrode is stably formed, and volume change of the negative electrode due to lithium doping / dedoping is suppressed. And the nonaqueous electrolyte battery based on this invention using such a negative electrode becomes the thing excellent in cycling characteristics.
[0016]
  The nonaqueous electrolyte battery of the present invention isA positive electrode containing a lithium composite oxide;Electrochemically lithium 400mAh / cm³Si that can be doped and dedoped₂N₂OAnd polyparaphenyleneOn the surface of the negative electrode active material layer containingConsist ofA negative electrode having a conductive polymer film deposited thereon, and a non-aqueous electrolyte interposed between the positive electrode and the negative electrode,In the negative electrode active material layer, polyparaphenylene is Si. ₂ N ₂ It is contained in the range of 0.1 parts by weight or more and 20 parts by weight or less with respect to 100 parts by weight of O, and the film thickness of the conductive polymer is 0.01 μm or more and 50 μm or less..
[0017]
  In the nonaqueous electrolyte battery according to the present invention as described above, lithium is electrochemically applied to the negative electrode at 400 mAh / cm.³Si that can be doped and dedoped₂N₂OAnd polyparaphenyleneOn the surface of the negative electrode active material layer containingConsist ofDeposit a conductive polymer film,The content of polyparaphenylene in the negative electrode active material layer is changed to Si. ₂ N ₂ With respect to 100 parts by weight of O, the range is 0.1 parts by weight or more and 20 parts by weight or less, and the film thickness of the conductive polymer is 0.01 μm or more and 50 μm or less,A conductive path in the negative electrode is stably formed, and volume change of the negative electrode due to lithium doping / dedoping is suppressed. And the nonaqueous electrolyte battery based on this invention using such a negative electrode becomes the thing excellent in cycling characteristics.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below.
[0019]
One structural example of the nonaqueous electrolyte battery to which the present invention is applied is shown in FIG. The nonaqueous electrolyte battery 1 includes a negative electrode 2, a negative electrode can 3 that contains the negative electrode 2, a positive electrode 4, a positive electrode can 5 that contains the positive electrode 4, and a separator disposed between the positive electrode 4 and the negative electrode 2. 6 and an insulating gasket 7, and the negative electrode can 3 and the positive electrode can 5 are filled with a non-aqueous electrolyte.
[0020]
The negative electrode 2 is formed by forming a negative electrode active material layer containing the negative electrode active material on a negative electrode current collector. For example, a nickel foil or the like is used as the negative electrode current collector. And in the non-aqueous electrolyte battery 1 of this invention, the electroconductive polymer is contained in the negative electrode 2 so that it may mention later.
[0021]
As a negative electrode active material, the metal which can form an alloy with lithium, or the alloy compound of the said metal is mentioned. The alloy compound referred to here is the chemical formula M where M is a metal element capable of forming an alloy with lithium._xM '_yLi_z(M ′ is one or more metal elements other than Li element and M element, and x is a numerical value larger than 0, and y and z are numerical values larger than 0.) . Further, in the present invention, elements such as B, Si, As and the like which are semiconductor elements are included in the metal element.
[0022]
Specific examples of the negative electrode active material include Mg, B, Al, Ga, In, Si, Ge, Sn, Pb, Sb, Bi, Cd, Ag, Zn, Hf, Zr, and Y and their alloy compounds. That is, for example, Li-Al, Li-Al-M (M is composed of one or more of 2A group, 3B group, 4B group transition metal element), AlSb, CuMgSb, and the like.
[0023]
Among the elements described above, it is preferable to use elements such as Si and Sn or alloys thereof in addition to the group 3B typical elements. Among these, Si or Si alloy is particularly suitable. Specifically, as Si or Si alloy, M_xSi, M_xA compound represented by Sn (M is one or more metal elements excluding Si or Sn), specifically, SiB_Four, SiB₆, Mg₂Si, Mg₂Sn, Ni₂Si, TiSi₂, MoSi₂CoSi₂NiSi₂, CaSi₂, CrSi₂, Cu_FiveSi, FeSi₂, MnSi₂, NbSi₂, TaSi₂, VSi₂, WSi₂, ZnSi₂Etc.
[0024]
Furthermore, in the nonaqueous electrolyte battery 1 of the present invention, a group 4B element other than carbon containing one or more nonmetallic elements can also be used as the negative electrode active material. The material may contain one or more 4B group carbons. Moreover, metal elements other than 4B group containing lithium may be contained. For example, SiC, Si_ThreeN_Four, Si₂N₂O, Ge₂N₂O, SiO_x(Where 0 <x ≦ 2), SnO_x(Where 0 <x ≦ 2), LiSiO, LiSnO, and the like.
[0025]
Group 4B elements other than carbon, including one or more non-metallic elements described above, must have the ability to electrochemically dope and dedope lithium. Preferably 400 mAh / cm^ThreeOr more, more preferably 500 mAh / cm^ThreeIt is preferable to have the above charge / discharge capacity. When calculating the charge / discharge capacity per volume, the true specific gravity value of the compound is used.
[0026]
The method for producing the negative electrode active material as described above is not limited, but a mechanical ironing method, a method of mixing raw material compounds and heat-treating in an inert atmosphere or a reducing atmosphere is employed.
[0027]
The doping of lithium into the negative electrode active material may be carried out electrochemically in the battery after the battery is made, and after the battery is made or before the battery is made, it is supplied electrochemically from the positive electrode or a lithium source other than the positive electrode. It does not matter. Or it may synthesize | combine as a lithium containing material in the case of material synthesis | combination, and may be contained in a negative electrode at the time of battery preparation.
[0028]
The negative electrode active material as described above may be used after being pulverized or may be used without being pulverized.
[0029]
When the negative electrode active material is used after being pulverized, it may be pulverized so that the maximum particle size is less than the thickness of the negative electrode active material layer, and the pulverization method is not limited, for example, ball mill pulverization, Examples include jet mill grinding. Specifically, the average particle diameter (volume average particle diameter) of the negative electrode active material after pulverization is preferably 50 μm or less, and more preferably 20 μm or less.
[0030]
When the negative electrode active material is used without being pulverized, the negative electrode active material layer can be produced as a molded body by chemical vapor deposition, sputtering, hot pressing, or the like.
[0031]
As a binder contained in a negative electrode active material layer, the well-known resin material etc. which are normally used as a binder of the negative electrode active material layer of this kind of nonaqueous electrolyte battery can be used.
[0032]
Further, the negative electrode active material layer may contain materials other than the negative electrode active material, the conductive polymer, and the binder. For example, a carbonaceous material may be included as a conductive material. For example, non-graphitizable carbon, artificial graphite, natural graphite, pyrolytic carbon, coke (pitch coke, needle coke, petroleum coke, etc.), graphite, glassy carbon, organic polymer compound fired body (phenol) Carbonaceous materials such as carbon fiber, activated carbon, and carbon black can be used. Moreover, you may include the material which does not contribute to charging / discharging.
[0033]
And in the nonaqueous electrolyte battery 1 of this invention, the negative electrode active material layer contains the conductive polymer.
[0034]
By including a conductive polymer in the negative electrode active material layer, it is possible to stably form a conductive path in the negative electrode and to suppress a change in volume of the negative electrode accompanying lithium dedoping. As a result, the non-aqueous electrolyte battery 1 has excellent cycle characteristics.
[0035]
The conductive polymer may be either n-type doped with cations and using electrons as carriers, or p-type doped with anions and using holes as carriers.
[0036]
Examples of conductive polymers include aliphatic conjugated polymer compounds such as polyacetylene, aromatic conjugated polymer compounds such as polyparaphenylene, heterocyclic conjugated polymer compounds such as polypyrrole and polythiophene, and polyaniline. A heteroatom-containing conjugated polymer compound, a mixed conjugated polymer compound such as polyphenylene vinylene, and a metal phthalocyanine polymer compound such as phthalocyanine and porphyrin.
[0037]
In order to contain such a conductive polymer in the negative electrode active material layer, the negative electrode active material and a binder are mixed to prepare a negative electrode mixture. May be added.
[0038]
When the conductive polymer is added to the negative electrode mixture, if the amount of the conductive polymer added is small, the effect of improving the cycle characteristics cannot be obtained sufficiently. In addition, if the amount of the conductive polymer added is too large, the proportion of the inactive portion that does not contribute to the reaction increases, and the proportion of the active portion that contributes to the reaction decreases accordingly, and the charge / discharge capacity per negative electrode Will fall. Therefore, the addition amount of the conductive polymer is preferably in the range of 0.1 parts by weight or more and 20 parts by weight or less with respect to 100 parts by weight of the negative electrode active material.
[0039]
Further, the conductive polymer is not only added to the negative electrode mixture, but may be deposited on the surface of the formed negative electrode active material layer.
[0040]
When the conductive polymer is deposited on the surface of the negative electrode active material layer, if the amount of the conductive polymer deposited is small, the effect of improving the cycle characteristics cannot be obtained sufficiently. In addition, if the amount of the conductive polymer deposited is too large, the proportion of the inactive portion that does not contribute to the reaction increases, and the proportion of the active portion that contributes to the reaction decreases accordingly, and charge / discharge per negative electrode. The ability will be reduced. Therefore, when depositing the conductive polymer on the surface of the negative electrode active material layer, it is preferable to deposit the conductive polymer so that the thickness of the conductive polymer is in the range of 0.01 μm to 50 μm.
[0041]
The negative electrode can 3 accommodates the negative electrode 2 and serves as an external negative electrode of the nonaqueous electrolyte battery 1.
[0042]
The positive electrode 4 is formed by forming a positive electrode active material layer containing a positive electrode active material on a positive electrode current collector. For example, an aluminum foil or the like is used as the positive electrode current collector.
[0043]
As the positive electrode active material, a metal oxide, a metal sulfide, a specific polymer, or the like can be used depending on the type of the target battery.
[0044]
Specifically, as the positive electrode active material, TiS₂, MoS₂, NbSe₂, V₂O_FiveLithium-free metal sulfides or oxides such as Li_xMO₂(Wherein M represents one or more transition metals, x varies depending on the charge / discharge state of the battery, and is generally 0.05 ≦ x ≦ 1.10.) be able to.
[0045]
As the transition metal M constituting this lithium composite oxide, Co, Ni, Mn and the like are preferable. As a specific example of such a lithium composite oxide, LiCoO₂LiNiO₂, Li_xNi_yCo_1-yO₂(Wherein x and y vary depending on the charge / discharge state of the battery, and usually 0 <x <1, 0.7 <y <1.02). Examples include lithium manganese composite oxides having a spinel structure. Can do. These lithium composite oxides can generate a high voltage and become a positive electrode active material excellent in energy density. For the positive electrode, a mixture of a plurality of these positive electrode active materials may be used.
[0046]
Moreover, when forming a positive electrode using the above positive electrode active material, a well-known electrically conductive material, a binder, etc. can be added.
[0047]
The positive electrode can 5 accommodates the positive electrode 4 and serves as an external positive electrode of the non-aqueous electrolyte battery 1.
[0048]
The separator 6 separates the positive electrode 4 and the negative electrode 2, and a known material that is usually used as a separator for this type of non-aqueous electrolyte battery can be used. For example, a polymer film such as polypropylene is used. Is used. Moreover, the thickness of a separator needs to be as thin as possible from the relationship between lithium ion conductivity and energy density. Specifically, the thickness of the separator is suitably 50 μm or less, for example.
[0049]
The insulating gasket 7 is incorporated in and integrated with the negative electrode can 3. The insulating gasket 7 is for preventing leakage of the non-aqueous electrolyte filled in the negative electrode can 3 and the positive electrode can 5.
[0050]
As the non-aqueous electrolyte, a solution in which an electrolyte is dissolved in an aprotic non-aqueous solvent is used.
[0051]
Any nonaqueous solvent can be used as long as it is used for this type of battery. For example, propylene carbonate, ethylene carbonate, diethyl carbonate, dimethyl carbonate, 1,2-dimethoxyethane, 1,2-diethoxyethane, γ-butyrolactone, tetrahydrofuran, 2-methyltetrahydrofuran, 1,3-dioxolane, 4 -Methyl-1,3-dioxolane, diethyl ether, sulfolane, methyl sulfolane, acetonitrile, propionitrile, anisole, acetate ester, butyrate ester, propionate ester and the like.
[0052]
As the electrolyte, any electrolyte that can be used in this type of battery can be used. To illustrate, LiClO_Four, LiAsF₆, LiPF₆, LiBF_Four, LiB (C₆H_Five)_Four, CH_ThreeSO_ThreeLi, CF_ThreeSO_ThreeLi, LiCl, LiBr, etc. are mentioned.
[0053]
In the non-aqueous electrolyte battery 1 of the present invention having the above-described configuration, since the negative electrode active material layer contains a conductive polymer, a conductive path in the negative electrode is stably formed, and lithium The volume change of the negative electrode accompanying dope undoping is suppressed. As a result, the nonaqueous electrolyte battery 1 of the present invention has excellent cycle characteristics.
[0054]
In the above-described embodiment, a non-aqueous electrolyte battery using a non-aqueous electrolyte is described as an example. However, the present invention is not limited to this, and a solid electrolyte containing an electrolyte salt is described. Alternatively, a solid electrolyte battery using a solid electrolyte obtained by impregnating an organic polymer with a nonaqueous solvent and an electrolyte salt, or a gel electrolyte battery using a gel electrolyte obtained by impregnating a matrix polymer with a nonaqueous solvent and an electrolyte salt Is also applicable.
[0055]
As the solid electrolyte, any inorganic solid electrolyte or polymer solid electrolyte can be used as long as the material has lithium ion conductivity. Examples of the inorganic solid electrolyte include lithium nitride and lithium iodide. The polymer solid electrolyte is composed of an electrolyte salt and a polymer compound that dissolves the electrolyte salt. Examples of the polymer compound include ether polymers such as poly (ethylene oxide) and cross-linked compounds, and ester compounds such as poly (methacrylate). A polymer, an acrylate polymer, or the like can be used alone, or can be copolymerized or mixed in the molecule.
[0056]
As the matrix polymer of the gel electrolyte, various polymers can be used as long as they can gel by absorbing the non-aqueous electrolyte. Specific examples of the matrix polymer include fluorine-based polymers such as poly (vinylidene fluoride) and poly (vinylidene fluoride-co-hexafluoropropylene), and ether-based polymers such as poly (ethylene oxide) and the same crosslinked products. Moreover, poly (acrylonitrile) etc. are mentioned. In particular, it is preferable to use a fluorine-based polymer from the viewpoint of redox stability. By containing an electrolyte salt, ionic conductivity is imparted.
[0057]
In the above-described embodiment, the secondary battery has been described as an example. However, the present invention is not limited to this, and can also be applied to a primary battery. The battery of the present invention is not particularly limited in shape, such as a cylindrical shape, a square shape, a coin shape, and a button shape, and can be various sizes such as a thin shape and a large size.
[0058]
【Example】
In order to confirm the effect of the present invention, a battery having the above-described configuration was produced and its characteristics were evaluated.
[0059]
<Example 1>
First, a negative electrode was produced as follows.
[0060]
Mg₂Si was pulverized to an average particle size of 15 μm. This Mg₂50 parts by weight of Si powder, 40 parts by weight of artificial graphite, and 10 parts by weight of polyvinylidene fluoride as a binder are mixed to form a negative electrode mixture, which is further dispersed in n-methylpyrrolidone to form a slurry. It was.
[0061]
Next, the obtained slurry was uniformly applied to both surfaces of a copper foil serving as a negative electrode current collector, dried, compression-molded with a roll press, and punched into a pellet shape having a diameter of 15.5 mm. Polyparaphenylene, which is a p-type conductive polymer, was electrochemically produced on the obtained pellet. Specifically, cupric chloride and LiAsF₆Soak pellets in a nitrobenzene solution of benzene with 1 mA / cm as the electrolyte²The polyparaphenylene was electrolytically polymerized on the pellet surface under the constant current conditions.
[0062]
Next, the positive electrode was produced as follows.
[0063]
LiCoO which becomes a positive electrode active material by mixing lithium carbonate and cobalt carbonate at a molar ratio of 0.5: 1 and firing in air at 900 ° C. for 5 hours.₂Got.
[0064]
Next, the obtained LiCoO₂91 parts by weight, 6 parts by weight of graphite as a conductive material, and 3 parts by weight of polyvinylidene fluoride as a binder were prepared to prepare a positive electrode mixture, which was further dispersed in n-methylpyrrolidone. A slurry was formed.
[0065]
Next, the obtained slurry was uniformly applied to both surfaces of an aluminum foil having a thickness of 20 μm serving as a positive electrode current collector, dried, compression-molded with a roll press machine, and punched into a pellet having a diameter of 15.5 mm.
[0066]
On the other hand, LiPF in an equal volume mixed solvent of ethylene carbonate and diethyl carbonate₆Was dissolved at a concentration of 1.0 mol / l to prepare a non-aqueous electrolyte.
[0067]
And the obtained negative electrode was accommodated in the negative electrode can, the positive electrode was accommodated in the positive electrode can, and the separator which consists of a 25-micrometer-thick polypropylene porous membrane was distribute | arranged between the negative electrode and the positive electrode. A coin-type nonaqueous electrolyte battery having a diameter of 20 mm and a height of 2.5 mm is obtained by injecting a nonaqueous electrolyte into the negative electrode can and the positive electrode can and caulking and fixing the negative electrode can and the positive electrode can through an insulating gasket. Was completed.
[0068]
<Example 2>
Mg as negative electrode active material₂Si instead of Si₂N₂A coin-type nonaqueous electrolyte battery was produced in the same manner as in Example 1 except that O was used.
[0069]
<Example 3>
First, polyparaphenylene powder was obtained as follows.
[0070]
Anhydrous aluminum chloride and anhydrous cupric chloride were added to benzene and stirred. After cooling, the resulting solid was washed with benzene. After evaporating the benzene, it was dispersed in hydrochloric acid and the solid was ground in boiling hydrochloric acid. Furthermore, polyparaphenylene powder was obtained by washing with sufficient water and drying.
[0071]
And the negative electrode was produced as follows using the obtained polyparaphenylene powder.
[0072]
Mg₂Si was pulverized to an average particle size of 15 μm. This Mg₂Mixing 50 parts by weight of Si powder, 40 parts by weight of artificial graphite, 5 parts by weight of polyvinylidene fluoride as a binder, and 5 parts by weight of polyparaphenylene powder to form a negative electrode mixture, A slurry was formed by dispersing in n-methylpyrrolidone.
[0073]
Next, the obtained slurry was uniformly applied to both sides of a copper foil serving as a negative electrode current collector, dried, compression-molded with a roll press machine, and punched into a pellet shape having a diameter of 15.5 mm to produce a negative electrode. .
[0074]
A coin-type nonaqueous electrolyte battery was produced in the same manner as in Example 1 except that the negative electrode obtained as described above was used.
[0075]
<Comparative example 1>
A coin-type nonaqueous electrolyte battery was produced in the same manner as in Example 1 except that polyparaphenylene was not formed on the negative electrode pellet.
[0076]
<Comparative example 2>
Mg as negative electrode active material₂Si instead of Si₂N₂A coin-type nonaqueous electrolyte battery was produced in the same manner as in Example 1 except that O was used and polyparaphenylene was not formed on the negative electrode pellet.
[0077]
The cycle characteristics were evaluated for each battery obtained as described above.
[0078]
First, a constant current and constant voltage discharge at 20 ° C. and 1 mA was performed up to an upper limit of 4.2 V, and then a 1 mA constant current discharge was performed up to a final voltage of 2.5 V. The above process was made into 1 cycle, and this was repeated 30 cycles. Then, the discharge capacity retention rate (%) at the 30th cycle when the discharge capacity at the 1st cycle was set to 100 was obtained. The initial capacity was almost the same for all batteries.
[0079]
Table 1 shows the measurement results of the discharge capacity retention rates for the batteries of Examples 1 to 3, Comparative Example 1 and Comparative Example 2.
[0080]
[Table 1]

[0081]
From Table 1, Mg as the negative electrode active material₂Example 1 using Si and Comparative Example 1 were compared, and Si was used as the negative electrode active material.₂N₂As is clear from comparison between Example 2 using O and Comparative Example 2, in Example 1 and Example 2 in which the conductive polymer was formed on the negative electrode, the conductive polymer was formed on the negative electrode. It can be seen that the discharge capacity retention rate is dramatically improved in comparison with Comparative Example 1 and Comparative Example 2 that were not present.
[0082]
Further, in addition to the formation of the conductive polymer on the negative electrode, as is clear from comparison between Example 3 in which the conductive polymer is mixed in the negative electrode and Comparative Example 1, in Example 3, the comparison was made. Compared to Example 1, it can be seen that a high discharge capacity retention rate is obtained.
[0083]
Therefore, it has been found that the discharge capacity retention ratio can be improved by forming a conductive polymer on the negative electrode or mixing a conductive polymer in the negative electrode.
[0084]
【The invention's effect】
  In the present invention, Mg₂Si or electrochemically lithium 400mAh / cm³Si that can be doped and dedoped₂N₂OAnd polyparaphenyleneOn the surface of the negative electrode active material layer containingConsist ofDeposit a conductive polymer film,The content of polyparaphenylene in the negative electrode active material layer is Mg ₂ Si or Si ₂ N ₂ By making the range of 0.1 parts by weight or more and 20 parts by weight or less with respect to 100 parts by weight of O, the film thickness of the conductive polymer is made 0.01 μm or more and 50 μm or less.In addition, it is possible to realize a negative electrode in which a conductive path in the negative electrode is stably formed and a change in volume of the negative electrode due to lithium doping and dedoping is suppressed.
[0085]
And in this invention, the nonaqueous electrolyte battery excellent in cycling characteristics is realizable by using the above negative electrodes.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a configuration example of a nonaqueous electrolyte battery according to the present invention.
[Explanation of symbols]
1 nonaqueous electrolyte battery, 2 negative electrode, 3 negative electrode can, 4 positive electrode, 5 positive electrode can, 6 separator, 7 insulating gasket

Claims (4)

A conductive polymer film made of polyparaphenylene is deposited on the surface of the negative electrode active material layer containing Mg ₂ Si and polyparaphenylene,
In the negative electrode active material layer, the polyparaphenylene is contained in the range of 0.1 parts by weight or more and 20 parts by weight or less with respect to 100 parts by weight of the Mg ₂ Si, and the film thickness of the conductive polymer negative but the 0.01μm or more, 50 [mu] m Ri der hereinafter used in the nonaqueous electrolyte battery. Conductive polymer film made of polyparaphenylene on the surface of a negative electrode active material layer containing Si ₂ N ₂ O and polyparaphenylene electrochemically capable of doping and dedoping lithium at 400 mAh / cm ³ or more Is deposited,
In the negative electrode active material layer, the polyparaphenylene is contained in a range of 0.1 parts by weight or more and 20 parts by weight or less with respect to 100 parts by weight of the Si ₂ N ₂ O, and the conductive polymer a negative electrode thickness, 0.01 [mu] m or more state, and are less 50 [mu] m, used in the nonaqueous electrolyte battery. A positive electrode containing a lithium composite oxide;
A negative electrode in which a conductive polymer film made of polyparaphenylene is deposited on the surface of a negative electrode active material layer containing Mg ₂ Si and polyparaphenylene;
A non-aqueous electrolyte interposed between the positive electrode and the negative electrode,
In the negative electrode active material layer, the polyparaphenylene is contained in the range of 0.1 parts by weight or more and 20 parts by weight or less with respect to 100 parts by weight of the Mg ₂ Si, and the film thickness of the conductive polymer Is a non-aqueous electrolyte battery of 0.01 μm or more and 50 μm or less. A positive electrode containing a lithium composite oxide;
Conductive polymer film made of polyparaphenylene on the surface of a negative electrode active material layer containing Si ₂ N ₂ O and polyparaphenylene electrochemically capable of doping and dedoping lithium at 400 mAh / cm ³ or more A negative electrode coated with,
A non-aqueous electrolyte interposed between the positive electrode and the negative electrode,
In the negative electrode active material layer, the polyparaphenylene is contained in a range of 0.1 parts by weight or more and 20 parts by weight or less with respect to 100 parts by weight of the Si ₂ N ₂ O, and the conductive polymer A nonaqueous electrolyte battery having a film thickness of 0.01 μm or more and 50 μm or less.

Images