KR101503528B1 - Anode and secondary battery - Google Patents

Abstract

A secondary battery capable of improving cycle characteristics is provided. An electrolyte is provided in the positive electrode 21 and the negative electrode 22 and the electrolyte is impregnated in the separator 23 provided between the positive electrode 21 and the negative electrode 22. The negative electrode 22 has a negative electrode current collector 22A and a negative electrode active material layer 22B formed thereon. The negative electrode active material layer 22B contains a negative electrode active material having a fine air group (a fine air group having a pore size of 3 nm or more and 50 nm or less) with silicon, and the volume of the fine air group per unit weight of silicon is 0.2 Lt; 3 > / g or less. The surface area of the negative electrode active material is suppressed to be small so that the electrolytic solution is difficult to decompose even when the negative electrode active material contains high activity silicon.

Negative electrode, battery, negative electrode active material, volume of micro air force

Description

≪ RTI ID = 0.0 > ANODE AND SECONDARY BATTERY <

The present invention relates to a negative electrode having a negative electrode current collector and a negative electrode active material layer formed thereon, and a secondary battery having the negative electrode.

2. Description of the Related Art In recent years, portable electronic devices such as a camera-integrated VTR (video tape recorder), a mobile phone, or a notebook computer have been widely used, and miniaturization, weight reduction, and longevity are strongly demanded. Along with this, development of batteries, particularly light-weight secondary batteries with high energy density, has been proceeding as a power source for portable electronic devices. Among them, secondary batteries (so-called lithium ion secondary batteries) using lithium intercalation and deintercalation in charge / discharge reactions are expected to have a larger energy density than lead-acid batteries and nickel-cadmium batteries.

The lithium ion secondary battery has an electrolyte solution together with a positive electrode and a negative electrode, and the negative electrode has a structure in which a negative electrode active material layer containing a negative electrode active material is formed on a negative electrode collector. Carbon materials are widely used as the negative electrode active material. In recent years, it has been studied to use silicon instead of a carbon material in order to further improve the battery capacity with the performance and diversification of portable electronic devices. This is because the theoretical capacity of silicon (4199 mAh / g) is significantly larger than the theoretical capacity of graphite (372 mAh / g), which is expected to greatly improve battery capacity.

However, when silicon is deposited as the negative electrode active material by the vapor deposition method, a large number of pores are formed in the negative electrode active material, thereby increasing the surface area. In this case, since the negative electrode active material is highly active, the electrolytic solution is liable to be decomposed during charging and discharging, and lithium is liable to be inactivated. As a result, the capacity of the secondary battery can be increased. On the other hand, if the charging and discharging are repeated, the cycle characteristic, which is an important characteristic of the secondary battery, is likely to deteriorate.

Therefore, even when silicon is used as the negative electrode active material, various attempts have been made to improve cycle characteristics.

Specifically, in the case where a silicon thin film is deposited a plurality of times by the vapor-phase deposition method, a technique of irradiating ions to the surface of the silicon thin film before deposition in the second and subsequent depositing steps (see, for example, Patent Document 1) (Refer to, for example, Patent Document 2) using a negative electrode current collector having a three-dimensional structure such as a sparkling metal or a fibrous metal sintered body, a technique of sintering silicon and integrating it with a negative electrode current collector 3, and 4).

[Patent Document 1] Japanese Patent Application Laid-Open No. 2005-293899

[Patent Document 2] Japanese Patent Application Laid-Open No. 2004-071305

[Patent Document 3] JP-A-11-339777

[Patent Document 4] Japanese Patent Application Laid-Open No. 11-339778

Further, there is a technique (for example, refer to Patent Documents 5 and 6) in which silicon particles are coated with a sintered material (ceramic) such as a metal oxide, a technique for forming an oxide layer such as silicon oxide on the surface of the silicon alloy layer (See, for example, Patent Document 7); a technique of reducing and depositing a conductive metal on a silicon powder (see, for example, Patent Document 8); a technique of coating a silicon compound particle with a metal , A technique of diffusing a metal element not alloying with lithium into silicon particles (see, for example, Patent Document 10), a technique of solid-solving copper in a silicon thin film (see, for example, Patent Document 11 ) Have also been proposed.

[Patent Document 5] Japanese Patent Application Laid-Open No. 2004-335334

[Patent Document 6] Japanese Patent Application Laid-Open No. 2004-335335

[Patent Document 7] Japanese Patent Application Laid-Open No. 2004-319469

[Patent Document 8] Japanese Unexamined Patent Publication No. 11-297311

[Patent Document 9] Japanese Patent Application Laid-Open No. 2000-036323

[Patent Document 10] Japanese Patent Application Laid-Open No. 2001-273892

[Patent Document 11] Japanese Unexamined Patent Application Publication No. 2002-289177

BACKGROUND ART [0002] In recent portable electronic devices, miniaturization, high performance, and multifunctionality have been increasing, and charging and discharging of secondary batteries tend to be repeated frequently, so cycle characteristics tend to deteriorate. In particular, in the lithium ion secondary battery using silicon as the negative electrode active material for high capacity, the cycle characteristics are likely to remarkably decrease due to the increase of the surface area described above. For this reason, it is desired to further improve the cycle characteristics of the secondary battery.

The present invention has been made in view of such problems, and an object thereof is to provide a negative electrode and a secondary battery capable of improving cycle characteristics.

The negative electrode of the present invention comprises a negative electrode active material having a negative electrode current collector and a negative electrode active material layer formed thereon, the negative electrode active material layer containing silicon and having a pore size of 3 nm or more and 50 nm or less, The volume of the air cleaner having a pore diameter of 3 nm or more and 50 nm or less as measured by a mercury porosimetry method using a porosimeter is 0.2 cm 3 / g or less per unit weight of silicon.

The secondary battery of the present invention comprises an anode and an anode together with an electrolytic solution and includes a negative electrode collector and a negative electrode active material layer formed on the negative electrode collector. The negative electrode active material layer contains silicon and has a pore size of 3 nm or more and 50 nm or less And the volume of the air cleaner having an pore size of 3 nm or more and 50 nm or less as measured by the mercury porosimetry using a mercury porosimeter is 0.2 cm 3 / g or less per unit weight of silicon.

The above-mentioned " cubic volume of the air cleaner " is obtained by replacing the penetration amount of mercury measured by mercury porosimetry using the mercury porosimeter with the volume of the clean air group. As a result, the "recirculation volume of pores having a pore size of 3 nm or more and 50 nm or less" refers to the sum of the amount of mercury penetration measured at a pore size of 3 nm or more and 50 nm or less with a pore volume of the pore diameter in the copper range. Further, the "recirculation volume of pores having a pore size of 3 nm or more and 20 nm or less" refers to the sum of the amount of mercury penetration measured at an pore diameter of 3 nm or more and 20 nm or less with a pore volume of the pore diameter in the copper range. This amount of mercury penetration is a value measured when the surface tension and the contact angle of mercury are set to 485 mN / m and 130 °, respectively, and the relationship between pore size and pressure is approximated by 180 / pressure = pore size. (Cm3 / g) per unit weight of silicon can be calculated from the weight (g) of silicon and the amount of penetration of mercury (= volume of cubic air group: cm3).

According to the negative electrode of the present invention, the negative electrode active material contains silicon and has a repelling group of 3 nm or more and 50 nm or less in pore diameter. The positive electrode active material has a pore size of 3 nm or more and 50 nm or less Since the volume of the fresh air group of the pore is 0.2 cm 3 / g or less per unit weight of silicon, even when the negative electrode active material contains silicon having high activity, it is difficult to react with other substances as compared with the case where the range is outside the range. Thus, according to the secondary battery having the negative electrode of the present invention, since the electrolyte is hardly decomposed during charging and discharging, the cycle characteristics can be improved. In this case, a higher effect can be obtained when the volume of the air cleaner having a pore size of 3 nm or more and 50 nm or less is 0.05 cm 3 / g or less, particularly 0 cm 3 / g, per unit weight of silicon.

Further, a higher effect can be obtained when the volume of the air cleaner having an pore diameter of 3 nm or more and 20 nm or less, as measured by mercury porosimetry using a mercury porosimeter, is 0.2 cm 3 / g or less per unit weight of silicon. In this case, a higher effect can be obtained when the volume of the repellent group having a pore diameter of 3 nm or more and 20 nm or less per unit weight of silicon is 0.05 cm 3 / g or less, particularly 0 cm 3 / g.

Further, even if the volume of the sub-air group per unit weight of silicon is originally outside the above-mentioned range, if the pores have a metal material that is not alloyed with the oxide-containing film or the electrode reaction material, The volume of the three air forces can be easily controlled. In this case, if the oxide-containing film is formed by a liquid phase method such as a liquid phase precipitation method or if the metal material is formed by a liquid phase method such as electrolytic plating method, the oxide-containing film or the metal material tends to enter the pores, Effect can be obtained.

It is also preferable that the negative electrode active material contains oxygen and the content of oxygen in the negative electrode active material is 3 to 40 atom% or less, or the negative electrode active material is composed of iron, cobalt, nickel, titanium, chromium and molybdenum Group or at least one of the negative electrode active material particles has an oxygen-containing region (oxygen and oxygen content is higher than the other region) in its thickness direction, Can be obtained.

Further, when the ten point average roughness Rz of the surface of the negative electrode collector is not less than 1.5 mu m and not more than 6.5 mu m, a higher effect can be obtained.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

1 shows a sectional configuration of a negative electrode according to an embodiment of the present invention. This negative electrode is used, for example, in an electrochemical device such as a secondary battery, and has a negative electrode collector 1 having a pair of surfaces and a negative electrode active material layer 2 formed thereon.

The negative electrode collector 1 is preferably made of a metal material having good electrochemical stability, electrical conductivity and mechanical strength. Examples of the metal material include copper, nickel, and stainless steel, among which copper is preferable. This is because high electrical conductivity is obtained.

In particular, it is preferable that the metal material constituting the negative electrode collector 1 contains one or two or more metal elements which do not form an intermetallic compound with the electrode reactant. When the electrode reaction material and the intermetallic compound are formed, the negative electrode active material layer 2 is affected by the pressure caused by the expansion and contraction of the negative electrode active material layer 2 during operation of the electrochemical device (for example, charging / discharging of the secondary battery) And the negative electrode active material layer 2 may be peeled off from the negative electrode current collector 1. Examples of these metallic elements include copper, nickel, titanium, iron, chromium and the like.

It is preferable that the above-mentioned metal material contains one or two or more kinds of metal elements to be alloyed with the negative electrode active material layer (2). The adhesion between the negative electrode current collector 1 and the negative electrode active material layer 2 is improved and the negative electrode active material layer 2 becomes difficult to separate from the negative electrode current collector 1. [ As the metal element that does not form an intermetallic compound with the electrode reaction material and is alloyed with the negative electrode active material layer 2, for example, when the negative electrode active material layer 2 contains silicon as the negative electrode active material, Nickel, iron, and the like. These metal elements are also preferable from the viewpoints of strength and conductivity.

The negative electrode collector 1 may have a single-layer structure or a multi-layer structure. In the case where the negative electrode current collector 1 has a multilayer structure, for example, the layer adjacent to the negative electrode active material layer 2 is made of a metal material alloyed with the negative electrode active material layer 2, and the non- .

The surface of the negative electrode current collector 1 is preferably roughened. This is because the adhesion between the negative electrode current collector 1 and the negative electrode active material layer 2 is improved by the so-called anchor effect. In this case, at least the surface of the negative electrode current collector 1 facing the negative electrode active material layer 2 may be roughened. Examples of the roughening method include a method of forming fine particles by electrolytic treatment. This electrolytic treatment is a method of forming fine irregularities by forming fine particles on the surface of the negative electrode collector 1 by electrolysis in an electrolytic bath. The copper foil subjected to this electrolytic treatment is generally called an " electrolytic copper foil ".

It is preferable that the ten-point average roughness Rz of the surface of the negative electrode current collector 1 is 1.5 m or more and 6.5 m or less. This is because the adhesion between the negative electrode current collector 1 and the negative electrode active material layer 2 is higher. Specifically, when the ten-point average roughness (Rz) is less than 1.5 탆, sufficient adhesion may not be obtained. When the average roughness Rz is larger than 6.5 탆, the negative electrode active material may contain a large amount of vacancies This is because.

The negative electrode active material layer 2 includes a negative electrode active material capable of absorbing and desorbing the electrode reactant. The negative electrode active material contains silicon as a constituent element. This is because the ability to absorb and discharge the electrode reaction material is large, and a high energy density is obtained. In addition, the negative electrode active material has a plurality of pores, and the pores of the plurality of pores are distributed over a wide range from about several nm to several thousand nm. Of these, when attention is paid to the air cleaner group (hereinafter simply referred to as " fine air cleaner ") having a fine pore size of 3 nm or more and 50 nm or less, the volume of the fine air group measured by a mercury porosimetry Is not more than 0.2 cm 3 / g per unit weight of silicon. The surface area of the negative electrode active material is suppressed to be small because the capacity of the fine air group is reduced, so that even when the negative electrode active material is highly active, it becomes difficult to react with other materials. Examples of the other materials include electrolytic solutions in the case where the negative electrode is used in a secondary battery.

The volume of the micro air group was obtained by replacing the amount of mercury penetrated by mercury porosimetry using the mercury porosimeter with the volume of the micro air group and the amount of mercury penetration was 485 mN / m and 130 deg., and the relationship between the pore diameter and the pressure is approximated by 180 / pressure = pore diameter. According to this method, when the pores of a plurality of pores are distributed over a wide range, the volume of the pores (amount of mercury entering the pores) can be measured for each specific pore range, (cm 3 / g) per unit weight of the above-mentioned silicon is calculated from the total sum of the amounts of mercury penetration measured at pore diameters of 3 nm to 50 nm, It is possible. The reason why the pores having a pore size of 3 nm or more and 50 nm or less are noticed when the range of the volume of the fine air group per unit weight of silicon is specified is because the volume of each pore is small but the total number of pores is very large, This has a large effect on the surface area.

Particularly, the volume occupied by the fine air group at a pore size of 3 nm or more and 50 nm or less per unit weight of silicon is preferably 0.05 cm 3 / g or less, more preferably 0 cm 3 / g. A higher effect can be obtained. The volume of the fine air group is 0 cm 3 / g. It is apparent from the fact that the volume of the fine air group is measured using the mercury porosimeter, the volume of the fine air group on the measurement result by the mercury porosimeter 0.0 > cm3 / g (< / RTI >

In this case, when attention is paid to a sub-air group (hereinafter simply referred to as " sub micro-air group ") having an extremely minute pore size of 3 nm or more and 20 nm or less among micro air groups having an average pore size of 3 nm or more and 50 nm or less, The volume of the ultrafine air group to be measured by the mercury infiltration method using a porosimeter is preferably 0.2 cm 3 / g or less, more preferably 0.05 cm 3 / g or less, and 0 cm 3 / g or less per unit weight of silicon desirable. In the fine air group, the volume of the ultrafine air group greatly affects the surface area of the negative electrode active material, so that a higher effect can be obtained.

The negative electrode active material layer 2 may contain an oxide-containing film in the micropores to set the volume of the fine air group per unit weight of silicon within the above-described range, if necessary, and may be alloyed with the electrode reaction material It may have metal that does not. This is because the oxide-containing film and the metal material enter the micropores and the volume of the microporous group becomes small. In this case, it is possible to make the volume of the fine air group per unit weight of silicon 0 cm 3 / g on the measurement result of the mercury porosimeter by sufficiently filling the micropores.

The oxide-containing film contains, for example, at least one oxide selected from the group consisting of silicon, germanium and tin. Of course, other oxides may be contained. The oxide-containing film may be formed by either a vapor phase method or a liquid phase method. Of these, a liquid phase method such as a liquid phase precipitation method, a sol-gel method, a coating method or a dip coating method is preferable, and a liquid phase precipitation method is more preferable. The oxide-containing film easily enters into the fine holes.

Examples of the metal material contained in the fine pores include those having a metal element which is not alloyed with the electrode reaction material, and at least one of the group consisting of iron, cobalt, nickel, zinc and copper, for example . Of course, the metal material may contain other metal elements. In addition, the metal material may be an alloy or a metal compound instead of a group. This metal material may be formed by either a vapor phase method or a liquid phase method. Among them, a liquid phase method such as an electrolytic plating method or an electroless plating method is preferable, and an electrolytic plating method is more preferable. The metal material tends to enter the fine holes and the plating time may be short. When the negative electrode active material layer 2 has a metallic material, the metallic material functions as a binder, so that the binding property between the negative electrode active materials is improved.

The negative electrode active material layer 2 may have either the oxide-containing film or the metal material described above, or both of them. However, in the case of only one of them, it is preferable to have an oxide-containing film. The oxide-containing film formed by the liquid phase method such as the liquid phase precipitation method is likely to enter the micropores than the metal formed by the liquid phase method such as the electrolytic plating method.

The negative electrode active material may be a single substance, an alloy, or a compound of silicon, and may have one or more phases thereof at least in part. These may be used alone or in combination.

The alloy of the present invention includes at least one metal element and at least one semimetal element in addition to being composed of two or more metal elements. Of course, the alloy in the present invention may contain a non-metallic element. The structure may include a solid solution, a process (eutectic mixture), an intermetallic compound, or a mixture of two or more of them.

As the alloy of silicon, for example, tin (Sn), nickel, copper, iron, cobalt, manganese (Mn), zinc, indium (In), silver (Ag), titanium, germanium ), Bismuth (Bi), antimony (Sb), and chromium.

Examples of the silicon compound include those having oxygen and carbon (C) as constituent elements other than silicon. The silicon compound may contain one or more of a series of elements described for the silicon alloy as a constituent element other than silicon, for example.

The negative electrode active material is connected to the negative electrode collector 1 and is grown in the thickness direction of the negative electrode active material layer 2 from the surface of the negative electrode collector 1. In this case, it is preferable that the negative electrode active material is formed by the vapor phase method and is alloyed at least at the interface between the negative electrode current collector 1 and the negative electrode active material layer 2 as described above. Specifically, the constituent elements of the negative electrode current collector 1 may diffuse into the negative electrode active material at the interfaces between them, or the constituent elements of the negative electrode active material may diffuse into the negative electrode current collector 1, The elements may diffuse to each other. This is because when the negative electrode active material layer 2 expands and shrinks during electrode reaction, it is hardly broken and the electronic conductivity between the negative electrode current collector 1 and the negative electrode active material layer 2 is improved.

As the vapor phase method, for example, a physical deposition method or a chemical deposition method, more specifically, a vacuum deposition method, a sputtering method, an ion plating method, a laser ablation method, a chemical vapor deposition (CVD) method, And a vapor phase growth method.

The negative electrode active material may have a plurality of particle shapes. The negative electrode active material may be formed by a single deposition process and may have a single layer structure or may be formed by a plurality of deposition processes to have a multi-layer structure in the particle. However, in the case of forming the negative electrode active material by a vapor deposition method accompanied by a high temperature at the time of deposition, it is preferable that the negative electrode active material has a multilayer structure in order to prevent the negative electrode current collector 1 from being thermally damaged. The time for which the negative electrode collector 1 is exposed to a high temperature is shorter than the case where the negative electrode active material is deposited in a plurality of steps (the negative electrode active materials are sequentially formed and deposited) This is because it is shorter.

In particular, the negative electrode active material preferably contains oxygen as a constituent element. And the expansion and contraction of the negative electrode active material layer 2 is suppressed. In the negative electrode active material layer 2, it is preferable that at least a part of oxygen is bonded to a part of silicon. In this case, the bonding state may be silicon monoxide or silicon dioxide, or another metastable state.

The content of oxygen in the negative electrode active material is preferably 3 to 40 atomic%. A higher effect can be obtained. Specifically, if the content of oxygen is less than 3 atomic%, the expansion and contraction of the negative electrode active material layer 2 may not be sufficiently suppressed. If the content of oxygen is more than 40 atomic%, there is a possibility that the resistance is excessively increased It is because. When the negative electrode is used together with the electrolytic solution in the electrochemical device, the film or the like formed by decomposition of the electrolytic solution is not included in the negative electrode active material. That is, when the content of oxygen in the negative electrode active material is calculated, oxygen in the film is not included.

The negative electrode active material containing oxygen can be formed, for example, by continuously introducing oxygen gas into the chamber when forming the negative electrode active material by the vapor phase method. Particularly, when a desired oxygen content can not be obtained only by introducing oxygen gas, a liquid (for example, steam or the like) may be introduced into the chamber as a supply source of oxygen.

The negative electrode active material preferably contains at least one metal element selected from the group consisting of iron, cobalt, nickel, titanium, chromium and molybdenum as constituent elements. The binding property of the negative electrode active material is improved, the expansion and contraction of the negative electrode active material layer 2 is suppressed, and the resistance of the negative electrode active material is lowered. The content of the metal element in the negative electrode active material can be arbitrarily set. However, when the negative electrode is used in a secondary battery, if the content of the metal element is excessively large, the negative electrode active material layer 2 must be made thick in order to obtain a desired battery capacity, (1).

The above-described negative electrode active material containing a metal element can be formed, for example, by using a vapor source in which a metallic element is mixed when forming a negative electrode active material by a vapor deposition method, or by using a multi-source vapor source .

It is preferable that the negative electrode active material has an oxygen-containing region having oxygen in its thickness direction, and the content of oxygen in the oxygen-containing region is higher than the content of oxygen in the other regions. And the expansion and contraction of the negative electrode active material layer 2 is suppressed. The region other than the oxygen-containing region may or may not contain oxygen. It is needless to say that, in the case where the region other than the oxygen-containing region also has oxygen, the content of oxygen is lower than the content of oxygen in the oxygen-containing region.

In this case, in order to further suppress the expansion and contraction of the negative electrode active material layer 2, a region other than the oxygen-containing region also has oxygen, and the negative electrode active material has a first oxygen-containing region (region having a lower oxygen content ) And a second oxygen-containing region (region having a higher oxygen content) having a higher oxygen content than the first oxygen-containing region. In this case, it is preferable that the second oxygen-containing region is sandwiched by the first oxygen-containing region, and it is more preferable that the first oxygen-containing region and the second oxygen-containing region are alternately repeatedly laminated. A higher effect can be obtained. The content of oxygen in the first oxygen-containing region is preferably as small as possible, and the content of oxygen in the second oxygen-containing region is the same as that in the case where the above-mentioned negative-electrode active material has oxygen.

The negative electrode active material having the first and second oxygen-containing regions can be formed by introducing an oxygen gas intermittently into the chamber or changing the amount of oxygen gas introduced into the chamber when the negative electrode active material is formed, for example, Lt; / RTI > Of course, when a desired oxygen content can not be obtained only by introducing oxygen gas, a liquid (for example, steam or the like) may be introduced into the chamber.

Further, between the first and second oxygen-containing regions, the content of oxygen may be clearly or unambiguously different. Particularly, when the introduction amount of the above-mentioned oxygen gas is continuously changed, the oxygen content may also be continuously changed. The first and second oxygen-containing regions are so-called " layers " when the introduction amount of oxygen gas is changed intermittently. On the other hand, when the introduction amount of oxygen gas is continuously changed, &Quot; In the latter case, the oxygen content in the negative electrode active material is distributed while repeating high and low. In this case, it is preferable that the content of oxygen varies stepwise or continuously between the first and second oxygen-containing regions. This is because, if the content of oxygen is abruptly changed, there is a possibility that the diffusion property of ions is lowered or the resistance is increased.

Here, with reference to Figs. 2 to 4, a detailed configuration example of the negative electrode will be described taking as an example a case where the negative electrode active material in the form of particles has a multilayer structure in its particle. (A) is a scanning electron microscope (SEM) photograph (secondary electron image), (B) is a SEM image (B) As shown in FIG. 3 shows the distribution of rate of change of the amount of invaded mercury.

As shown in FIG. 2, when the negative electrode active material forms a plurality of particle shapes (negative electrode active material particles 201), the negative electrode active material has a plurality of pores 202. Specifically, on the surface of the roughened negative electrode current collector 1, a plurality of projections (for example, fine particles formed by electrolytic treatment) are present. In this case, the negative electrode active material is deposited and laminated on the surface of the negative electrode collector 1 a plurality of times by the vapor-phase deposition method or the like, so that the negative electrode active material particles 201 grow stepwise in the thickness direction for each of the above- A plurality of pores 202 are formed depending on the dense structure, the multi-layer structure, and the surface structure of the plurality of negative electrode active material particles 201.

The pores 202 include three types of pores 202A, 202B, and 202C classified according to the cause of the occurrence. The pores 202A are gaps formed between the negative electrode active material particles 201 as the negative electrode active material particles 201 are grown for each of the protrusions present on the surface of the negative electrode collector 1. [ The pore 202B is a gap formed between the protruding portions of the negative electrode active material particles 201 due to the formation of a hair-like fine protrusion (not shown) on the surface of the negative electrode active material particle 201. These pores 202B may occur over the entire exposed surface of the negative electrode active material particles 201, or may occur only in a part thereof. The pore 202C is a gap between the layers as the anode active material particles 201 have a multi-layer structure. The pores 202B are formed not only on the exposed surface (the outermost surface) of the negative electrode active material particles 201 but also on the exposed surfaces of the negative electrode active material particles 201, since the above-described whiskered fine protrusions are formed on the surfaces of the negative electrode active material particles 201 at the time of formation of the negative electrode active material particles 201 But also between layers. Of course, the pores 202 may include other pores caused by other causes other than the above-mentioned causes.

When the penetration amount (V) of mercury into the pores 202 is measured while the pressure P is gradually increased by using the mercury porosimeter, the rate of change of invasion amount (? V /? P) They are distributed together. 3, the abscissa represents the pore diameter (nm) of the pores 202, and the ordinate represents the rate of change of the penetration amount of mercury into the pores 202. The rate of change of the penetration amount of mercury is distributed so as to show two peaks (P1, P2) at a pore diameter of 3 nm or more and 3000 nm or less, which can be measured using a mercury porosimeter. The peak P1 on the side of the pore diameter is caused mainly by the presence of the pores 202A and the range of the pore diameter is 50 nm or more and 3000 nm or less. On the other hand, the peak P2 on the pore diameter side is caused mainly by the presence of the pores 202B and 202C, and the pore size distribution range is 3 nm or more and 50 nm or less. 3 is a value obtained by normalizing the rate of change of the penetration amount of mercury at the peak P1 (maximum value of the rate of change in pore diameter of 50 nm to 3000 nm) to 1. In addition,

4, after the plurality of negative electrode active material particles 201 are formed, when the metal material 203 is formed by the electrolytic plating method or the like, the metal material 203 enters the pores 202. That is, the metal material 203 is a gap (fine pores 202B) between fine protruding portions of the male-like shape formed on the surface of the negative electrode active material particles 201 and entering the interstices (pores 202A) between the adjacent negative electrode active material particles 201, (Pores 202C) in the negative electrode active material particles 201. The fact that the metal material 203 is dotted on the surface of the negative electrode active material particles 201 on the uppermost layer in Fig. And that the above-mentioned fine protrusions are present at the point of the dotted portion.

As shown in Figs. 2 to 4, when the particle-shaped negative electrode active material has a multi-layer structure in its particle, the micro pores include both pores 202B and 202C. In this case, the metal material 203 may be contained in the pores 202B and 202C only if the volume of the fine air group per unit weight of silicon is within the above range. From the viewpoint of the performance of the entire negative electrode, Is preferably contained in the pores 202A, and more preferably, the pores 202A are filled in the pores 202A. The binding property of the negative electrode active material is improved through the metal material 203 and the negative electrode active material layer 2 is hardly expanded and contracted.

When the particle-shaped negative electrode active material does not have a multi-layer structure in the particle (a single layer structure), the micropores contain only the pores 202B because no pores 202C occur.

Although the oxide-containing film is formed by the liquid phase deposition method instead of the metal material, the oxide-containing film grows along the surface of the negative electrode active material particles 201, 202B, and 202C. In this case, when the precipitation time is elongated, the oxide containing film enters the pores 202A.

This negative electrode is produced, for example, by the following procedure.

First, the negative electrode current collector 1 is prepared, and then the surface of the negative electrode collector 1 is roughed as necessary. Subsequently, silicon is deposited on the negative electrode current collector 1 by a vapor-phase deposition method or the like to form a negative electrode active material. In the case of forming the negative electrode active material, the negative electrode active material may be formed into a single-layer structure by a single deposition process or may be formed into a multi-layer structure by a plurality of deposition processes. In the case of forming the anode active material to have a multilayer structure by the vapor-phase deposition method, silicon may be deposited a plurality of times while relatively moving the anode current collector 1 with respect to the evaporation source. Alternatively, The silicon may be deposited a plurality of times while the current collector 1 is fixed and the shutter is opened and closed repeatedly. Thereafter, an oxide-containing film or a metal material which is not alloyed with the electrode reaction material may be formed by a liquid phase method or the like. In the case of forming an oxide-containing film by a liquid phase precipitation method, a dissolved species which is liable to coordinate fluorine as an anion-trapping agent is added to a solution of a fluoride complex such as silicon and mixed, and then a negative electrode active material The negative electrode current collector 1 is immersed so that the fluorine anions generated from the fluoride complex are supported by dissolved species to deposit oxides on the surface of the negative electrode active material. In this case, instead of the fluoride complex, a compound such as silicon which causes another anion such as a sulfate ion may be used. As a result, the negative electrode active material layer 2 is formed, so that the negative electrode is completed.

According to this negative electrode, the negative electrode active material contains silicon and has a fine air group (a fine air group having an aperture of 3 nm or more and 50 nm or less in pore size), and a volume of a fine air group measured by a mercury porosimeter using a mercury porosimeter Is 0.2 cm 3 / g or less per unit weight of the silicon. Therefore, even when the negative electrode active material contains silicon having high activity, it is difficult to react with other substances as compared with the case where the negative electrode active material is out of the range. Therefore, it can contribute to the improvement of the cycle characteristics of the electrochemical device using the negative electrode. In this case, when the volume of the fine air group per unit weight of silicon is 0.05 cm 3 / g or less, particularly 0 cm 3 / g, a higher effect can be obtained.

Particularly, when the volume of the ultrafine air group (the air cleaner group of 3 nm or more and 20 nm or less in pore diameter) measured by mercury porosimetry using a mercury porosimeter is 0.2 cm 3 / g or less per unit weight of silicon, Can be obtained. In this case, a higher effect can be obtained when the volume of the ultrafine air group per unit weight of silicon is 0.05 cm 3 / g or less, particularly 0 cm 3 / g.

Further, even if the volume of the fine air group per unit weight of silicon is outside the above-mentioned range, it is possible to obtain a fine air group per unit weight of silicon Can be easily controlled. In this case, if the oxide-containing film is formed by a liquid phase method such as a liquid phase precipitation method, or if the metal material is formed by a liquid phase method such as an electrolytic plating method, the oxide-containing film or the metal material tends to enter the micropores. High effect can be obtained.

It is also preferable that the negative electrode active material contains oxygen and the content of oxygen in the negative electrode active material is from 3 atomic% to 40 atomic% or the negative electrode active material is composed of iron, cobalt, nickel, titanium, chromium and molybdenum (The region having oxygen and the content of oxygen being higher than the other region) in the thickness direction of the negative electrode active material particle, the higher effect is obtained when the negative electrode active material particle contains the oxygen- Can be obtained.

When the surface of the negative electrode collector 1 facing the negative electrode active material layer 2 is roughened by the fine particles formed by electrolytic treatment, the surface of the negative electrode active material layer 2 between the negative electrode collector 1 and the negative electrode active material layer 2 The adhesion can be enhanced. In this case, a higher effect can be obtained if the ten-point average roughness Rz of the surface of the negative electrode collector 1 is 1.5 m or more and 6.5 m or less.

Next, an example of using the above-described negative electrode will be described. Here, taking an example of a secondary battery as an example of an electrochemical device, a negative electrode is used in a secondary battery as follows.

(First secondary battery)

5 and 6 show a sectional configuration of the first secondary battery, and FIG. 6 shows a cross section taken along the line VI-VI in FIG. The secondary battery described here is, for example, a lithium ion secondary battery in which the capacity of the negative electrode 22 appears based on the occlusion and release of lithium which is an electrode reaction material.

In this secondary battery, the battery element 20 having a flat winding structure is accommodated in the battery can 11. [

The battery can 11 is, for example, a rectangular external member. As shown in Fig. 6, this prismatic casing member has a rectangular cross section in the longitudinal direction or a substantially rectangular cross section (including a part of a curved line), and it is possible to use not only rectangular prismatic cells but also elliptical And the like. That is, the rectangular external member is a container member having a bottomed rectangular shape or a bottomed elliptical shape, which has a rectangular shape or a substantially rectangular (elliptical) opening formed by connecting arcs in a straight line. 6 shows a case where the battery can 11 has a rectangular cross-sectional shape. The cell structure including the battery can 11 is called a so-called square type.

The battery can 11 is made of, for example, a metal material containing iron, aluminum (Al), or an alloy thereof, and may have a function as an electrode terminal. In this case, iron harder than aluminum is preferable in order to suppress the expansion of the secondary battery by making the battery can 11 hard (difficult to deform) during charging and discharging. When the battery can 11 is made of iron, it may be plated with, for example, nickel (Ni).

The battery can 11 has a hollow structure in which one end and the other end are respectively closed and opened, and an insulating plate 12 and a battery lid 13 are attached to the open end thereof to seal the battery can 11. The insulating plate 12 is disposed between the battery element 20 and the battery lid 13 and perpendicular to the winding peripheral surface of the battery element 20 and made of polypropylene or the like. The battery lid 13 is made of, for example, the same material as the battery can 11, and may have a function as an electrode terminal in the same manner.

A terminal plate 14 serving as a positive terminal is provided on the outer side of the battery lid 13 and the terminal plate 14 is electrically insulated from the battery lid 13 through the insulating case 16. The insulating case 16 is made of, for example, polybutylene terephthalate. A through hole is formed in the substantially center of the battery lid 13 and is electrically connected to the terminal plate 14 at the through hole and electrically connected to the positive electrode pin 14 through the gasket 17, 15 are inserted. The gasket 17 is made of, for example, an insulating material, and its surface is coated with asphalt.

In the vicinity of the periphery of the battery lid (13), the opening valve (18) and the injection hole (19) are formed. When the internal pressure of the secondary battery becomes equal to or more than a certain level due to an internal short circuit or heating from the outside or the like, the opening valve 18 is disconnected from the battery lid 13, Open. The injection hole 19 is closed by a sealing member 19A made of, for example, a stainless steel sphere.

The battery element 20 is wound after being laminated with the positive electrode 21 and the negative electrode 22 through the separator 23 and is formed into a flat shape according to the shape of the battery can 11. A positive electrode lead 24 made of aluminum or the like is attached to an end portion (for example, an inner end portion) of the positive electrode 21 and an end portion (for example, an outer end portion) And a negative electrode lead 25 is attached. The positive electrode lead 24 is welded to one end of the positive electrode pin 15 and is electrically connected to the terminal plate 14 and the negative electrode lead 25 is welded to the battery can 11 and electrically connected thereto.

The positive electrode 21 is formed, for example, with a positive electrode active material layer 21B on both surfaces of a strip-shaped positive electrode collector 21A. The positive electrode current collector 21A is made of a metal material such as aluminum, nickel, or stainless steel. The positive electrode active material layer 21B contains a positive electrode active material, and may contain a binder, a conductive agent, and the like as necessary.

The positive electrode active material includes any one or more of positive electrode materials capable of occluding and releasing lithium which is an electrode reaction material. As the positive electrode material, for example, lithium cobalt oxide, lithium nickel oxide, or a solid solution (Li (Ni _x Co _y Mn _z ) O ₂ containing them, x, y and z are 0 <x < (LiMn ₂ O ₄ ) or a solid solution thereof (Li (Mn _{2 - v} Ni _v ) O ₄ , where y <1, 0 <z <1, x + y + z = 1) or a spinel structure of lithium manganese oxide and the value of v is v &lt; 2). As the positive electrode material, for example, a phosphoric acid compound having an olivine structure such as lithium iron phosphate (LiFePO ₄ ) may also be used. This is because a high energy density is obtained. In addition, the positive electrode material may contain, in addition to the above, an oxide such as titanium oxide, vanadium oxide or manganese dioxide, a disulfide such as iron disulfide, titanium disulfide or molybdenum sulfide, or a metal such as sulfur, polyaniline or polythiophene Or may be a conductive polymer.

The negative electrode 22 has the same structure as the above-described negative electrode. For example, the negative electrode active material layer 22B is formed on both surfaces of the strip-shaped negative electrode collector 22A. The configurations of the negative electrode current collector 22A and the negative electrode active material layer 22B are the same as those of the negative electrode current collector 1 and the negative electrode active material layer 2 in the negative electrode. It is preferable that the charging capacity of the negative electrode active material capable of occluding and releasing lithium is larger than the charging capacity of the positive electrode 21. [

The separator 23 separates the positive electrode 21 and the negative electrode 22 to allow ions of the electrode reaction material to pass therethrough while preventing a short circuit of the current due to the contact of the positive electrode. The separator 23 is made of, for example, a porous film made of a synthetic resin such as polytetrafluoroethylene, polypropylene or polyethylene, or a porous film made of ceramic, and the like. It is acceptable.

The separator 23 is impregnated with an electrolytic solution as a liquid electrolyte. This electrolytic solution contains a solvent and an electrolytic salt dissolved therein.

The solvent contains, for example, one or more non-aqueous solvents such as organic solvents. Examples of the nonaqueous solvent include carbonic ester solvents such as ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, ethylmethyl carbonate or methylpropyl carbonate. This is because excellent capacity characteristics, storage characteristics and cycle characteristics are obtained. These may be used alone or in combination. Among them, as the solvent, it is preferable to mix a high viscosity solvent such as ethylene carbonate or propylene carbonate with a low viscosity solvent such as dimethyl carbonate, ethyl methyl carbonate or diethyl carbonate. The dissociation of the electrolyte salt and the mobility of the ions are improved, so that a higher effect can be obtained.

It is also preferable that the solvent contains a halogenated carbonic ester. This is because a stable coating film is formed on the surface of the negative electrode 22 to suppress the decomposition reaction of the electrolyte solution, thereby improving the cycle characteristics. As the halogenated carbonic ester, fluorinated carbonic ester is preferable, and carbonic acid difluoroethylene is more preferable. A higher effect can be obtained. Examples of the difluoroethylene carbonate include 4,5-difluoro-1,3-dioxolane-2-one and the like.

Further, it is preferable that the solvent contains a cyclic carbonate ester having an unsaturated bond. This is because the cycle characteristics are improved. As the cyclic carbonic ester having an unsaturated bond, for example, vinylene carbonate, vinyl ethylene carbonate, or the like may be cited, and they may be mixed and used.

It is also preferable that the solvent contains sultone. The cycle characteristics are improved and the expansion of the secondary battery is suppressed. As this sultone, for example, 1,3-propanesultone and the like can be mentioned.

Electrolytic salts include, for example, one kind or two or more kinds of light metal salts such as lithium salts. Examples of the lithium salt include lithium hexafluorophosphate (LiPF ₆ ), lithium perchlorate (LiClO ₄ ), lithium hexafluorosilicate (LiAsF ₆ ), and the like. This is because excellent capacity characteristics, storage characteristics and cycle characteristics are obtained. These may be used alone or in combination. Among them, lithium hexafluorophosphate is preferable as the electrolyte salt. Since the internal resistance is lowered, a higher effect can be obtained.

It is also preferable that the electrolytic salt contains a compound having boron and fluorine. The cycle characteristics are improved and the expansion of the secondary battery is suppressed. Examples of the compound having boron and fluorine include lithium tetrafluoroborate and the like.

The content of the electrolyte salt in the solvent is, for example, 0.3 mol / kg or more and 3.0 mol / kg or less. This is because excellent capacity characteristics can be obtained.

This secondary battery is manufactured, for example, by the following procedure.

First, the positive electrode 21 is produced. First, the positive electrode active material, the binder, and the conductive agent are mixed to form a positive electrode mixture, and then the resulting mixture is dispersed in an organic solvent to obtain a paste-like positive electrode mixture slurry. Subsequently, the positive electrode material mixture slurry is uniformly coated on both surfaces of the positive electrode collector 21A by using a doctor blade or a bar coater and dried. Thereafter, the positive electrode active material layer 21B is formed by compression molding using a roll press or the like while heating as required. In this case, the compression molding may be repeated a plurality of times.

Next, the negative electrode 22 is formed by forming the negative electrode active material layer 22B on both surfaces of the negative electrode collector 22A by the same procedure as the above-described procedure for manufacturing the negative electrode.

Next, the battery element 20 is manufactured by using the positive electrode 21 and the negative electrode 22. First, the positive electrode lead 24 and the negative electrode lead 25 are attached to the positive electrode current collector 21A and the negative electrode current collector 22A by welding or the like. Subsequently, after the positive electrode 21 and the negative electrode 22 are laminated via the separator 23, they are wound in the longitudinal direction. Finally, the battery element 20 is formed by molding it into a flat shape.

Finally, the secondary battery is assembled. First, after the battery element 20 is housed in the battery can 11, the insulating plate 12 is disposed on the battery element 20. Subsequently, after the positive electrode lead 24 and the negative electrode lead 25 are respectively connected to the positive electrode fins 15 and the battery can 11 by welding or the like, the battery can 11 is attached to the open end of the battery can 11 by laser welding, (13). Finally, the electrolytic solution is injected into the battery can 11 from the injection hole 19 to impregnate the separator 23, and then the injection hole 19 is closed with the sealing member 19A. Thus, the secondary battery shown in Figs. 5 and 6 is completed.

In this secondary battery, when charging is performed, for example, lithium ions are discharged from the positive electrode 21, and are stored in the negative electrode 22 through the electrolytic solution impregnated with the separator 23. On the other hand, when discharging is performed, for example, lithium ions are discharged from the negative electrode 22, and the negative electrode 22 is stored in the positive electrode 21 through the electrolytic solution impregnated with the separator 23.

According to this prismatic secondary battery, since the negative electrode 22 has the same structure as the above-described negative electrode, it is difficult to reduce the discharge capacity even if charge and discharge are repeated. Therefore, the cycle characteristics can be improved. In this case, since the cycle characteristics are improved when the negative electrode 22 contains silicon favorable for high capacity, higher effects can be obtained than when the negative electrode 22 contains other negative electrode materials such as carbon materials. Other effects of the secondary battery are the same as those of the above-described negative electrode.

Particularly, when the battery can 11 is made of a hard metal, the negative electrode 22 is less likely to be damaged when the negative electrode active material layer 22B expands and contracts as compared with a case of a soft film. Therefore, the cycle characteristics can be further improved. In this case, if the battery can 11 is made of iron harder than aluminum, a higher effect can be obtained.

(Second secondary battery)

Figs. 7 and 8 show a sectional configuration of the second secondary battery, and Fig. 8 enlargedly shows a part of the wound electrode body 40 shown in Fig. This secondary battery is a lithium ion secondary battery similar to the above-described first secondary battery. The positive electrode 41 and the negative electrode 42 are disposed inside the battery can 31 almost in the shape of a hollow cylinder, And a pair of insulating plates 32 and 33 are accommodated. The battery structure including the battery can 31 is called a so-called cylindrical shape.

The battery can 31 is made of, for example, the same metal material as the battery can 11 in the above-described first secondary battery, and one end and the other end are closed and opened, respectively. The pair of insulating plates 32 and 33 are disposed so as to extend perpendicularly to the winding circumferential surface of the winding electrode body 40 therebetween.

A battery lid 34 and a safety valve mechanism 35 and a positive temperature coefficient device (PTC device) 36 provided in the battery lid 34 are fixed to the open end of the battery can 31 through a gasket 37 Respectively. Thereby, the inside of the battery can 31 is sealed. The battery lid 34 is made of the same material as the battery can 31, for example. The safety valve mechanism 35 is electrically connected to the battery lid 34 through the thermosensitive element 36. In this safety valve mechanism 35, when the internal pressure becomes equal to or more than a predetermined value due to an internal short-circuit or heating from the outside or the like, the disc plate 35A is reversed and the gap between the battery lid 34 and the wound electrode body 40 As shown in Fig. The resistance of the resistance element 36 increases as the temperature rises, thereby restricting the current, thereby preventing abnormal heat generation due to the large current. The gasket 37 is made of, for example, an insulating material, and its surface is coated with asphalt.

For example, a center pin 44 may be inserted into the center of the wound electrode body 40. In this wound electrode body 40, a positive electrode lead 45 composed of aluminum or the like is connected to the positive electrode 41, and a negative electrode lead 46 composed of nickel or the like is connected to the negative electrode 42. The positive electrode lead 45 is welded to the safety valve mechanism 35 and electrically connected to the battery lid 34 and the negative electrode lead 46 is welded to the battery can 31 and electrically connected thereto.

The positive electrode 41 is, for example, a positive electrode active material layer 41B formed on both surfaces of a strip-shaped positive electrode collector 41A. The negative electrode 42 has the same structure as the above-described negative electrode. For example, the negative electrode active material layer 42B is formed on both surfaces of the strip-shaped negative electrode collector 42A. The constitution of the positive electrode current collector 41A, the positive electrode active material layer 41B, the negative electrode current collector 42A, the negative electrode active material layer 42B and the separator 43 and the composition of the electrolytic solution were the same as those of the above- The constitution of the positive electrode current collector 21A, the positive electrode active material layer 21B, the negative electrode current collector 22A, the negative electrode active material layer 22B and the separator 23 and the composition of the electrolytic solution are the same.

This secondary battery is manufactured, for example, as follows.

First, a positive electrode active material layer 41B is formed on both surfaces of the positive electrode current collector 41A by the same procedure as that for the production of the positive electrode 21 and the negative electrode 22 in the above-described first secondary battery, for example. The positive electrode 41 is fabricated and the negative electrode 42 having the negative electrode active material layer 42B formed on both surfaces of the negative electrode collector 42A is manufactured. Subsequently, the positive electrode lead 45 is attached to the positive electrode 41, and the negative electrode lead 46 is attached to the negative electrode 42. Subsequently, the positive electrode 41 and the negative electrode 42 are wound through the separator 43 to form the wound electrode body 40, and the tip of the positive electrode lead 45 is welded to the safety valve mechanism 35 The tip end portion of the negative electrode lead 46 is welded to the battery can 31 and then the wound electrode body 40 is sandwiched by the pair of insulating plates 32 and 33 to be accommodated in the battery can 31. Subsequently, an electrolytic solution is injected into the battery can 31 to impregnate the separator 43. Finally, the battery lid 34, the safety valve mechanism 35 and the thermosensitive element 36 are caulked and fixed to the opening end of the battery can 31 through the gasket 37. [ As a result, the secondary battery shown in Figs. 7 and 8 is completed.

When the secondary battery is charged, for example, lithium ions are discharged from the positive electrode 41 and are stored in the negative electrode 42 through the electrolytic solution. On the other hand, when the discharge is performed, for example, lithium ions are discharged from the negative electrode 42, and are stored in the positive electrode 41 through the electrolytic solution.

According to this cylindrical secondary battery, since the negative electrode 42 has the same configuration as the above-described negative electrode, the cycle characteristics can be improved. The other effects of the secondary battery are the same as those of the first secondary battery.

(Third secondary battery)

Fig. 9 shows an exploded perspective view of the third rechargeable battery, and Fig. 10 shows an enlarged cross section taken along the line X-X shown in Fig. This secondary battery is one wherein the wound electrode body 50 to which the positive electrode lead 51 and the negative electrode lead 52 are attached is housed inside the film-like casing member 60. The battery structure including this sheathing member 60 is called a so-called laminated film type.

The positive electrode lead 51 and the negative electrode lead 52 are led out in the same direction from the inside of the sheathing member 60 to the outside, for example. The positive electrode lead 51 is made of a metal material such as aluminum and the negative electrode lead 52 is made of a metal material such as copper, nickel or stainless steel. They are, for example, in the form of a thin plate or mesh.

The exterior member 60 is made of, for example, an aluminum laminated film in which a nylon film, an aluminum foil and a polyethylene film are bonded in this order. This outer covering member 60 has a structure in which the outer edges of two rectangular aluminum laminate films are adhered to each other by fusion bonding or an adhesive so that the polyethylene film faces the wound electrode body 50 have.

Adhesive films 61 are inserted between the sheathing member 60 and the positive electrode lead 51 and the negative electrode lead 52 to prevent entry of outside air. The adhesion film 61 is made of a material having adhesion to the positive electrode lead 51 and the negative electrode lead 52. Examples of such a material include polyolefin resins such as polyethylene, polypropylene, modified polyethylene and modified polypropylene.

The sheathing member 60 may be made of a laminate film having another laminated structure instead of the aluminum laminate film described above, or may be made of a polymer film such as polypropylene or a metal film.

The wound electrode body 50 is wound after the positive electrode 53 and the negative electrode 54 are laminated via the separator 55 and the electrolyte 56 and the outermost peripheral portion thereof is protected by the protective tape 57.

The positive electrode 53 is, for example, a positive electrode active material layer 53B formed on both surfaces of a positive electrode current collector 53A having a pair of surfaces. The negative electrode 54 has a structure similar to that of the above-described negative electrode. For example, the negative electrode active material layer 54B is formed on both surfaces of the strip-shaped negative electrode collector 54A. The configuration of the positive electrode collector 53A, the positive electrode active material layer 53B, the negative electrode collector 54A, the negative electrode active material layer 54B and the separator 55 is the same as that of the above- The positive electrode active material layer 21A, the positive electrode active material layer 21B, the negative electrode collector 22A, the negative electrode active material layer 22B and the separator 23. [

The electrolyte (56) contains an electrolytic solution and a polymer compound for supporting the electrolytic solution, that is, a so-called gel electrolyte. The gel electrolyte is preferable because a high ionic conductivity (for example, 1 mS / cm or more at room temperature) is obtained and leakage is prevented. The electrolyte 56 is formed between the positive electrode 53 and the separator 55 and between the negative electrode 54 and the separator 55, for example.

Examples of the polymer compound include polyacrylonitrile, polyvinylidene fluoride, copolymers of polyvinylidene fluoride and polyhexafluoropyrene, polytetrafluoroethylene, polyhexafluoropropylene, polyethylene oxide, polypropylene oxide, Polyvinyl alcohol, polymethyl methacrylate, polyacrylic acid, polymethacrylic acid, styrene-butadiene rubber, nitrile-butadiene rubber, polystyrene or polycarbonate, and the like. These may be used alone or in combination. Among them, polyacrylonitrile, polyvinylidene fluoride, polyhexafluoropropylene or polyethylene oxide is preferable as the polymer compound. Because it is electrochemically stable.

The composition of the electrolytic solution is the same as the composition of the electrolytic solution in the first secondary battery. However, in this case, the solvent is not only a liquid solvent but also a concept including ionic conductivity capable of dissociating the electrolyte salt. Therefore, when a polymer compound having ionic conductivity is used, the polymer compound is also included in the solvent.

Instead of the gel-like electrolyte 56 in which the electrolytic solution is supported by the polymer compound, the electrolytic solution may be used as it is. In this case, the separator 55 is impregnated by the electrolytic solution.

The secondary battery having the gel electrolyte 56 is manufactured, for example, as follows.

First, a positive electrode 53 (positive electrode active material layer) having positive electrode active material layers 53B formed on both surfaces of the positive electrode collector 53A is formed by the same procedure as that of the positive electrode 21 and the negative electrode 22 in the above- And a negative electrode 54 having negative electrode active material layers 54B formed on both surfaces of the negative electrode collector 54A is manufactured. Subsequently, a precursor solution containing an electrolytic solution, a polymer compound, and a solvent is prepared and applied to each of the positive electrode 53 and the negative electrode 54, followed by volatilization of the solvent to form a gel-like electrolyte 56. Subsequently, the positive electrode lead 51 is attached to the positive electrode collector 53A, and the negative electrode lead 52 is attached to the negative electrode collector 54A. Subsequently, the positive electrode 53 and the negative electrode 54, on which the electrolyte 56 is formed, are laminated via the separator 55 and then wound in the longitudinal direction and the protective tape 57 is bonded to the outermost peripheral portion, (50). Next, for example, the wound electrode body 50 is sandwiched between the sheathing members 60 and the outer edge portions of the sheathing member 60 are brought into close contact with each other by thermal fusion or the like to seal the wound electrode body 50 . At this time, the adhesive film 61 is inserted between the positive electrode lead 51 and the negative electrode lead 52 and the exterior member 60. As a result, the secondary battery shown in Figs. 9 and 10 is completed.

The secondary battery may be manufactured as follows. First, after the positive electrode lead 51 and the negative electrode lead 52 are attached to the positive electrode 53 and the negative electrode 54, respectively, the positive electrode 53 and the negative electrode 54 are laminated and wound through the separator 55 And the protective tape 57 is adhered to the outermost periphery of the wound electrode body 50 to form a winding which is a precursor of the wound electrode body 50. Subsequently, the winding member is sandwiched between the exterior members 60, and the outer peripheral edge excluding the outer peripheral edge of one side is brought into close contact by thermal fusion or the like to be housed inside the exterior member 60 of the bag shape. Subsequently, a composition for an electrolyte containing an electrolytic solution, a monomer as a raw material of a polymer compound, a polymerization initiator and, if necessary, another material such as a polymerization inhibitor is prepared, and the electrolyte composition is injected into the bag- The opening of the exterior member 60 is sealed by heat sealing or the like. Finally, the monomer is thermally polymerized into a polymer compound to form a gel-like electrolyte (56). As a result, the secondary battery shown in Figs. 9 and 10 is completed.

According to this laminated film type secondary battery, since the negative electrode 54 has the same structure as the above-described negative electrode, the cycle characteristics can be improved. The other effects of the secondary battery are the same as those of the first secondary battery.

<Examples>

The embodiments of the present invention will be described in detail.

(Example 1-1)

The laminated film type secondary battery shown in Figs. 9 and 10 was fabricated by the following procedure. At this time, the capacity of the anode 54 was determined to be a lithium ion secondary battery based on insertion and extraction of lithium.

First, a positive electrode 53 was prepared. First, lithium carbonate (Li ₂ CO ₃ ) and cobalt carbonate (CoCO ₃ ) were mixed at a molar ratio of 0.5: 1 and then calcined at 900 ° C for 5 hours in air to obtain a lithium-cobalt composite oxide (LiCoO ₂ ). Subsequently, 91 parts by mass of a lithium-cobalt composite oxide as a positive electrode active material, 6 parts by mass of graphite as a conductive agent and 3 parts by mass of polyvinylidene fluoride as a binder were mixed to prepare a positive electrode mixture, And dispersed in pyrrolidone to obtain a paste-like positive electrode material mixture slurry. Finally, the positive electrode material mixture slurry was uniformly coated on both surfaces of a positive electrode current collector 53A made of a strip-shaped aluminum foil (thickness = 12 mu m), dried and compression-molded by a roll press machine to form a positive electrode active material layer 53B ).

Next, a negative electrode 54 was prepared. First, a negative electrode current collector 54A (thickness = 18 mu m, ten-point average roughness (Rz) = 3.5 mu m) made of an electrolytic copper foil is prepared, and oxygen gas and, if necessary, water vapor are introduced into the chamber, Silicon was deposited on both surfaces of the anode current collector 54A by electron beam evaporation using an evaporation source to form a plurality of particle-shaped anode active materials so as to have a single layer structure (thickness = 5.8 mu m). At this time, silicon having a purity of 99% was used as an evaporation source, the deposition rate was 10 nm / second, and the oxygen content in the negative electrode active material was 3 atomic%. Finally, silicon oxide (SiO ₂ ) was precipitated by the liquid phase precipitation method to form an oxide containing film, thereby forming a negative electrode active material layer 54B. In the case of forming this oxide-containing film, a dissolved species which is liable to coordinate fluorine is added as an anion-based chelating agent to a solution of a fluoride complex of silicon and mixed, and then a negative electrode current collector 54A having a negative electrode active material formed thereon is immersed , The fluorine anion generated from the fluoride complex is supported by the dissolved species to deposit an oxide on the surface of the negative electrode active material. At this time, by adjusting the deposition time of the oxide (the amount of the oxide-containing film to be contained in the fine pores), the volume of the fine pore group per unit weight of silicon was adjusted to 0.2 cm 3 / g. The volume of the fine air group per unit weight of silicon is determined by subtracting the weight of the negative electrode collector 54A from the total weight of the negative electrode collector 54A on which the negative electrode active material is formed (the weight of silicon as the negative electrode active material) Was calculated from the value of the amount of mercury intrusion (volume of the micro air group) measured for pores of 3 nm to 50 nm using a mercury porosimeter (Autopore 9500 series) manufactured by Micromeritics.

Next, a positive electrode lead 51 made of aluminum is welded to one end of the positive electrode current collector 53A, and a negative electrode lead 52 made of nickel is welded to one end of the negative electrode collector 54A Respectively. Subsequently, a polymer separator 55 (thickness = 23 mu m) having a three-layer structure in which a positive electrode 53 and a film mainly composed of porous polyethylene are sandwiched by a porous polypropylene- And the polymer separator 55 are stacked in this order and wound in the longitudinal direction and then the outermost layer winding portion is fixed with the protective tape 57 made of an adhesive tape to form the precursor of the wound electrode body 50 To form a winding. Subsequently, a three-layer laminated film (total thickness = 100 mu m) in which nylon (thickness = 30 mu m), aluminum (thickness = 40 mu m) and unleaved polypropylene And then the outer edges except for one side are thermally fused to each other to accommodate the winding body in the outer shape of the bag-like outer member 60. Subsequently, an electrolytic solution was injected from the opening of the exterior member 60 and impregnated into the separator 55, thereby forming the wound electrode body 50. [

When this electrolyte solution was prepared, a mixed solvent of ethylene carbonate (EC) and diethyl carbonate (DEC) was used as a solvent, and lithium hexafluorophosphate (LiPF ₆ ) was used as an electrolytic salt. At this time, the composition (EC: DEC) of the mixed solvent was 50:50 by weight and the concentration of the electrolyte salt was 1 mol / kg.

Finally, the opening of the exterior member 60 was thermally fused and sealed in a vacuum atmosphere to complete a laminate film-type secondary battery. Regarding this secondary battery, by adjusting the thickness of the positive electrode active material layer 53B so that the charge / discharge capacity of the negative electrode 54 is larger than the charge / discharge capacity of the positive electrode 53, So as not to precipitate.

(Examples 1-2 to 1-14)

(Examples 1-2), 0.09 cm3 / g (Examples 1-3), and 0.08 cm3 / g (Example 1- (2)) instead of 0.2 cm3 / g, (Examples 1-6), 0.07 cm3 / g (Examples 1-7), 0.04 cm3 / g (Examples 1-5), 0.07 cm3 / , 0.03 cm 3 / g (Examples 1-9), 0.02 cm 3 / g (Examples 1-10), 0.01 cm 3 / g (Examples 1-11), 0.005 cm 3 / Cm 3 / g (Example 1-13) or 0 cm 3 / g (Example 1-14).

(Comparative Example 1-1)

The procedure was the same as that of Example 1-1, except that an oxide-containing film was not formed. In this case, the volume of the fine air group per unit weight of silicon was 0.4 cm 3 / g.

(Comparative Examples 1-2 and 1-3)

The same procedure as in Example 1-1 was performed except that the volume of the fine air group per unit weight of silicon was 0.35 cm 3 / g (Comparative Example 1-2) or 0.3 cm 3 / g (Comparative Example 1-3) .

The cycle characteristics of the secondary batteries of Examples 1-1 to 1-14 and Comparative Examples 1-1 to 1-3 were examined, and the results shown in Table 1 and FIG. 11 were obtained.

When examining the cycle characteristics, a cycle test was carried out in the following procedure to determine the discharge capacity retention rate. First, in order to stabilize the battery state, the battery was charged and discharged one cycle in an atmosphere at 23 占 폚, and then charged and discharged again to measure the discharge capacity at the second cycle. Subsequently, the discharge capacity was measured at the 101th cycle by charging and discharging 99 cycles in the atmosphere. Finally, the discharge capacity retention ratio (%) = (discharge capacity at the 101st cycle / discharge capacity at the second cycle) × 100 was calculated. At this time, as the charging condition, the battery was charged until the battery voltage reached 4.2 V at a constant current density of 3 mA / cm 2, and then charged until a current density reached 0.3 mA / cm 2 at a constant voltage of 4.2 V . As discharge conditions, discharge was continued until the battery voltage reached 2.5 V at a constant current density of 3 mA / cm 2.

The procedure and conditions for examining the cycle characteristics are the same for the evaluation of the characteristics relating to the following series of examples and comparative examples.

As shown in Table 1 and FIG. 11, when the silicon oxide was formed by the liquid phase precipitation method as the oxide containing film, the discharge capacity retention ratio gradually increased as the volume of the fine air group per silicon unit weight became smaller. This result shows that when the oxide-containing film enters the micropore, the surface area of the negative electrode active material becomes small, and therefore, the electrolytic solution becomes difficult to decompose upon charging and discharging. In this case, in Examples 1-1 to 1-14 in which the volume was 0.2 cm 3 / g or less, the discharge capacity retention ratios were significantly higher than those in Comparative Examples 1-1 to 1-3 which were outside the range. In particular, when the volume is 0.05 cm 3 / g or less, the discharge capacity retention ratio is higher, and when the discharge capacity is 0 cm 3 / g, the discharge capacity retention ratio is the maximum. In view of these points, in the secondary battery of the present invention, when the oxide-containing film is formed together with the negative electrode active material containing silicon, by setting the volume of the fine air group per unit weight of silicon to 0.2 cm 3 / g or less, . In this case, it was also confirmed that a higher effect was obtained when the concentration was 0.05 cm 3 / g or less, particularly 0 cm 3 / g.

(Examples 2-1 to 2-9)

Except that the negative electrode active material was formed so as to have a six-layer structure by depositing and depositing silicon six times while reciprocally moving the negative electrode collector 54A relative to the evaporation source, 2, 1-4, 1-7, and 1-10 to 1-14. At this time, the deposition rate was set at 100 nm / sec.

(Comparative Example 2)

The procedure was the same as that of Comparative Example 1-3 except that the negative electrode active material had a six-layer structure as in Examples 2-1 to 2-9.

The cycle characteristics of the secondary batteries of Examples 2-1 to 2-9 and Comparative Example 2 were examined, and the results shown in Table 2 and Fig. 12 were obtained.

As shown in Table 2 and Fig. 12, in Examples 2-1 to 2-9 in which the negative electrode active material had a six-layer structure, results similar to those of Examples 1-1 to 1-14 in a single layer structure were obtained. That is, in Examples 2-1 to 2-9 in which the capacity of the fine air group per unit weight of silicon is 0.2 cm 3 / g or less, the discharge capacity retention ratio is significantly higher than that of Comparative Example 2 outside the range, and 0.05 cm 3 / Cm 3 / g, the discharge capacity retention ratio was further increased. From these points, it was confirmed that, in the secondary battery of the present invention, the cycle characteristics were improved even when the number of the negative electrode active materials was changed.

(Examples 3-1 to 3-6)

Examples 2-1, 2-2, and 2 were prepared in the same manner as in Example 2-1 except that a solution of the fluoride complex of germanium was used in place of the solution of the fluoride complex of silicon and germanium oxide (GeO ₂ ) -4, 2-5, 2-7, 2-9.

(Comparative Example 3)

The same procedure as in Comparative Example 2 was carried out except that germanium oxide was formed as an oxide-containing film in the same manner as in Examples 3-1 to 3-6.

(Examples 4-1 to 4-6)

Examples 2-1, 2-2, and 2 were prepared in the same manner as in Example 2-1 except that a solution of the fluoride complex of tin was used in place of the solution of the fluoride complex of silicon and tin oxide (SnO ₂ ) was formed instead of silicon oxide as the oxide- -4, 2-5, 2-7, 2-9.

(Comparative Example 4)

The same procedure as in Comparative Example 2 was carried out except that tin oxide was formed as an oxide-containing film in the same manner as in Examples 4-1 to 4-6.

The cycle characteristics of the secondary batteries of Examples 3-1 to 3-6, 4-1 to 4-6 and Comparative Examples 3 and 4 were examined, and the results shown in Tables 3 and 4 were obtained.

As shown in Tables 3 and 4, also in Examples 3-1 to 3-6 and 4-1 to 4-6 in which germanium oxide or tin oxide was formed by the liquid phase precipitation method as the oxide containing film, silicon oxide was formed The same effects as those of Examples 1-1 to 1-14 were obtained. That is, in Examples 3-1 to 3-6 and 4-1 to 4-6 in which the volume of the fine air group per unit weight of silicon was 0.2 cm 3 / g or less, the discharge capacity retention ratio was wider than Comparative Examples 3 and 4, And 0.05 cm 3 / g or less, especially 0 cm 3 / g, the discharge capacity retention ratio was further increased. In this case, the discharge capacity retention rate tended to be higher in the case of forming silicon oxide. From these points, it was confirmed that, in the secondary battery of the present invention, even when the kind of the oxide-containing film was changed, the cycle characteristics were improved and a higher effect was obtained by using silicon oxide.

(Examples 5-1 to 5-3)

Except that the sol-gel method (Example 5-1), the coating method (Example 5-2), or the dip coating method (Example 5-3) was used instead of the liquid phase deposition method as the method of forming the oxide-containing film The procedure is the same as in Example 2-5.

As a result of examining the cycle characteristics of the secondary batteries of Examples 5-1 to 5-3, the results shown in Table 5 were obtained. Table 5 also shows the results of Examples 2-5 and Comparative Example 2.

As shown in Table 5, in Examples 5-1 to 5-3 in which an oxide-containing film was formed by a sol-gel method or the like, as in Example 2-5 in which an oxide-containing film was formed by a liquid phase precipitation method, The capacity retention rate has greatly increased. In this case, the discharge capacity retention rate tends to be higher in the case of using the liquid phase precipitation method. From these points, it was confirmed that, in the secondary battery of the present invention, even when the method for forming an oxide-containing film was changed, the cycle characteristics were improved and a higher effect was obtained by using the liquid phase precipitation method.

(Example 6-1)

The same procedures as in Examples 2-1 to 2-9 were conducted except that a metal material not alloyed with lithium was formed in place of the oxide containing film after the negative electrode active material was formed. In forming this metal material, cobalt was deposited on both surfaces of the anode current collector 54A by electrolytic plating while supplying air to the plating bath. At this time, as a plating solution, a cobalt plating solution manufactured by High Purity Chemical Co., Ltd. was used, and the current density was set to 2 A / dm ² to 5 A / dm ² , and the plating rate was set to 10 nm / second. Further, by adjusting the plating time, the volume of the fine air group per unit weight of silicon was set to 0.2 cm 3 / g.

(Examples 6-2 to 6-6)

(Example 6-2), 0.05 cm 3 / g (Example 6-3) and 0.02 cm 3 / g (Example 6-2) instead of 0.2 cm 3 / g in terms of the volume of the fine air group per unit weight of silicon, 4), 0.005 cm 3 / g (Example 6-5) or 0 cm 3 / g (Example 6-6), respectively.

(Comparative Example 6)

The same procedure as in Comparative Example 2 was carried out except that a metal material was formed in the same manner as in Example 6-1.

The cycle characteristics of the secondary batteries of Examples 6-1 to 6-6 and Comparative Example 6 were examined, and the results shown in Table 6 were obtained.

As shown in Table 6, when cobalt was formed by electrolytic plating as a metal material, the same results as in Examples 2-1 to 2-9 in which an oxide-containing film was formed were obtained. That is, in Examples 6-1 to 6-6 in which the volume of the fine air group per unit weight of silicon is 0.2 cm 3 / g or less, the discharge capacity retention ratio is significantly higher than that of Comparative Example 6 which is outside the range, and 0.05 cm 3 / Cm 3 / g, the discharge capacity retention ratio was further increased. From these points, in the secondary battery of the present invention, when the metal material is formed together with the negative electrode active material containing silicon, the capacity of the fine air group per unit weight of silicon is 0.2 cm 3 / g or less, It is confirmed that a higher effect can be obtained when the concentration is 0.05 cm 3 / g or less, particularly 0 cm 3 / g.

(Examples 7-1 to 7-6)

The same procedure as in Examples 6-1 to 6-6 was performed except that a metal material was formed by an electroless plating method instead of the electrolytic plating method. At this time, an electroless cobalt plating solution manufactured by High Purity Chemical Co., Ltd. was used as the plating solution, and the plating time was set to 60 minutes.

(Comparative Example 7)

The same procedure as in Comparative Example 2 was carried out except that a metal material was formed by electroless plating as in Examples 7-1 to 7-6.

The cycle characteristics of the secondary batteries of Examples 7-1 to 7-6 and Comparative Example 7 were examined, and the results shown in Table 7 were obtained.

As shown in Table 7, in Examples 7-1 to 7-6 in which the metal material was formed by the electroless plating method, the same results as in Examples 6-1 to 6-6 in which the metal material was formed by the electrolytic plating method . That is, in Examples 7-1 to 7-6 in which the volume of the fine air group per unit weight of silicon is 0.2 cm 3 / g or less, the discharge capacity retention ratio is significantly higher than that of Comparative Example 7 which is outside the range, and 0.05 cm 3 / Cm 3 / g, the discharge capacity retention ratio was further increased. From these points, it was confirmed that the cycle characteristics were improved in the secondary battery of the present invention even when the method of forming the metal material was changed.

(Examples 8-1 to 8-4)

(Example 8-2), a zinc plating solution (Example 8-3), or a copper plating solution (Example 8-4) instead of a cobalt plating solution as a metal material forming material, Was used, and the same procedure as in Example 6-4 was carried out. As this time, the current density, when the case of using a nickel plating solution and has a 2A / dm ² to 10A / dm ^2, using plating liquid iron has 2A / dm ² to If the 5A / dm ^2, and the case of using the zinc plating solution has, and a 1A / dm ² to 3A / dm ^2, using the copper plating solution has been to 2A / dm ² to 8A / dm ^2. The series of plating solutions described above are all manufactured by Japan High Purity Chemical Co.,

The cycle characteristics of the secondary batteries of Examples 8-1 to 8-4 were examined, and the results shown in Table 8 were obtained. Table 8 also shows the results of Example 6-4 and Comparative Example 6.

As shown in Table 8, in Examples 8-1 to 8-4 in which nickel or the like was formed as a metal material, the discharge capacity retention ratio was about the same as that in Example 6-4 in which cobalt was formed, and the discharge capacity retention ratio Was significantly higher than that of Comparative Example 6. In this case, the discharge capacity retention rate tended to be higher when cobalt was used as the metal material. From these points, it was confirmed that, in the secondary battery of the present invention, even when the kind of the metal material was changed, the cycle characteristics were improved and a higher effect was obtained by using cobalt as the metal material.

(Examples 9-1 to 9-6)

(Example 9-1), 10 atom% (Example 9-2), and 20 atom% (Example 9-3) in place of 3 atom% ), 30 atomic% (Example 9-4), 40 atomic% (Example 9-5), or 45 atomic% (Example 9-6) .

As a result of examining the cycle characteristics of the secondary batteries of Examples 9-1 to 9-6, the results shown in Table 9 and Fig. 13 were obtained. Table 9 also shows the results of Examples 2-5 and Comparative Example 2.

As shown in Table 9, in Examples 9-1 to 9-6 in which the content of oxygen in the negative electrode active material was different, the discharge capacity retention ratio was significantly higher than that of Comparative Example 2, as in Example 2-5. In this case, as shown in Table 9 and FIG. 13, as the oxygen content increases, the discharge capacity retention rate tends to decrease after the increase, and when the content is less than 3 atom%, the discharge capacity retention rate is greatly reduced . However, when the content exceeds 40 atomic%, a sufficient discharge capacity retention rate was obtained, but the battery capacity decreased. From these points, it can be seen that, in the secondary battery of the present invention, even when the content of oxygen in the negative electrode active material is changed, the cycle characteristics are improved, and when the content is 3 atom% or more and 40 atom% .

(Examples 10-1 to 10-3)

By depositing silicon while introducing oxygen gas or the like continuously into the chamber and intermittently introducing oxygen gas or the like into the chamber instead of depositing silicon to contain oxygen in the negative electrode active material, the first oxygen-containing region and the oxygen- Except that the negative electrode active material was formed so that the second oxygen-containing regions were alternately stacked. In this case, the oxygen content in the second oxygen-containing region was set to 3 atomic%, and the number of oxygen atoms in the second oxygen-containing region was 2 (Example 10-1), 4 (Example 10-2), or 6 (Example 10 -3).

As a result of examining the cycle characteristics of the secondary batteries of Examples 10-1 to 10-3, the effects shown in Table 10 were obtained. Table 10 also shows the results of Examples 2-5 and Comparative Example 2.

As shown in Table 10, in Examples 10-1 to 10-3 in which the negative electrode active material had the first and second oxygen-containing regions, the discharge capacity retention ratio was significantly higher than in Comparative Example 2, as in Example 2-5 . In this case, the discharge capacity retention rate tended to increase as the number of the second oxygen-containing regions increased. In view of these points, in the secondary battery of the present invention, the cycle characteristics are improved even when the negative electrode active material particles are configured to have the first and second oxygen-containing regions, and when the number of the second oxygen- It was confirmed that an effect was obtained.

(Examples 11-1 to 11-6)

A procedure similar to that of Example 2-5 was performed except that a negative active material containing both of them was formed using a metal element having a purity of 99.9% together with silicon having a purity of 99% as an evaporation source. (Example 11-1), nickel (Example 11-2), molybdenum (Example 11-3), titanium ((Example 11-4), chromium (Example 11- 5) or cobalt (Example 11-6) was used. At this time, the deposition amount of the metal element was adjusted so that the content of the metal element in the negative electrode active material was 5 atomic%.

The cycle characteristics of the secondary batteries of Examples 11-1 to 11-6 were examined, and the results shown in Table 11 were obtained. Table 11 also shows the results of Examples 2-5 and Comparative Example 2.

As shown in Table 11, in Examples 11-1 to 11-6 in which the negative electrode active material contained a metal element together with silicon, the discharge capacity retention ratio was significantly higher than in Comparative Example 2, as in Example 2-5. In this case, the discharge capacity retention rate tended to be higher than in Example 2-5. From these points, it was confirmed that, in the secondary battery of the present invention, even when the negative electrode active material contains a metal element, the cycle characteristics are improved and a higher effect can be obtained by including the metal element.

(Example 12-1)

A procedure similar to that of Example 2-5 was performed except that the negative electrode active material was formed by RF magnetron sputtering method instead of the electron beam vapor deposition method. At this time, silicon having a purity of 99.99% was used as a target, and the deposition rate was 0.5 nm / sec.

(Example 12-2)

A procedure similar to that of Example 2-5 was performed except that the negative electrode active material was formed by using the CVD method instead of the electron beam vapor deposition method. At this time, silane and argon were used as raw materials and excitation gases, respectively, and deposition rate and substrate temperature were set to 1.5 nm / sec and 200 deg.

The cycle characteristics of the secondary batteries of Examples 12-1 and 12-2 were examined, and the results shown in Table 12 were obtained. Table 12 also shows the results of Examples 2-5 and Comparative Example 2.

As shown in Table 12, in Examples 12-1 and 12-2 in which the method of forming the negative electrode active material was different, the discharge capacity retention ratio was significantly higher than in Comparative Example 2, as in Example 2-5. In this case, as a method of forming the negative electrode active material, the discharge capacity retention rate tends to be increased in the order of the CVD method, the sputtering method, and the electron beam evaporation method. From these points, it was confirmed that, in the secondary battery of the present invention, even when the method of forming the negative electrode active material was changed, the cycle characteristics were improved and a higher effect was obtained by using the vapor deposition method.

(Examples 13-1 to 13-7)

(Example 13-1), 1.5 占 퐉 (Example 13-2), and 2.5 占 퐉 (Example 13-3) instead of 3.5 占 퐉 in terms of the ten-point average roughness Rz of the surface of the anode current collector 54A, , 4.5 占 퐉 (Example 13-4), 5.5 占 퐉 (Example 13-5), 6.5 占 퐉 (Example 13-6), or 7 占 퐉 (Example 13-7) 5.

The cycle characteristics of the secondary batteries of Examples 13-1 to 13-7 were examined, and the results shown in Table 13 and Fig. 14 were obtained. Table 13 also shows the results of Examples 2-5 and Comparative Example 2.

As shown in Table 13, in Examples 13-1 to 13-7 in which the ten-point average roughness Rz was different, the discharge capacity retention ratio was significantly higher than that in Comparative Example 2, as in Example 2-5. In this case, as shown in Table 13 and Fig. 14, the discharge capacity retention rate tends to decrease after the ten-point average roughness Rz increases and the ten-point average roughness Rz becomes less than 1.5 mu m, or If it is larger than 6.5 mu m, the discharge capacity retention rate is greatly reduced. In this regard, in the secondary battery of the present invention, cycle characteristics are improved even when the ten-point average roughness Rz of the surface of the negative electrode collector 54A is changed, and the ten-point average roughness Rz is set to 1.5 Mu m or less, a higher effect was obtained.

(Example 14-1)

Except that 4-fluoro-1,3-dioxolan-2-one (FEC) which was fluorinated carbonic ester (monofluoroethylene carbonate) was used in place of EC as a solvent, I went through the procedure.

(Example 14-2)

(EC: DFEC: DEC) of a mixed solvent was prepared by adding 4,5-difluoro-1,3-dioxolane-2-one (DFEC), which is fluorinated carbonic ester (carbonic acid difluoroethylene) Was changed to a weight ratio of 25: 5: 70 by the same procedure as in Example 2-5.

(Examples 14-3 and 14-4)

Except that vinylene carbonate (VC: Example 14-3) or vinylethylene carbonate (VEC: Example 14-4), which is a cyclic carbonate ester having an unsaturated bond as a solvent, was added to the electrolytic solution. I went through the same procedure. At this time, the content of VC and VEC in the electrolytic solution was 10 wt%.

(Example 14-5)

The procedure was the same as that of Example 14-1 except that 1,3-propanesultone (PRS), which is a sulphone as a solvent, was added to the electrolytic solution. At this time, the concentration of PRS in the electrolytic solution was 1 wt%.

(Example 14-6)

The procedure was the same as that of Example 14-1 except that lithium tetrafluoroborate (LiBF ₄ ) was added as an electrolytic solution to the electrolytic solution. At this time, the concentration of LiBF _{4 in} the electrolytic solution was 0.1 mol / kg.

As a result of examining the cycle characteristics of the secondary batteries of Examples 14-1 to 14-6, the results shown in Table 14 were obtained. Table 14 also shows the results of Examples 2-5 and Comparative Example 2.

At this time, as to the secondary batteries of Examples 2-5 and 14-5, the expansion characteristics as well as the cycle characteristics were examined. In examining the expansion characteristics, the expansion rate was obtained by charging the secondary battery in the following procedure. First, in order to stabilize the battery state, the battery was charged and discharged one cycle in an atmosphere at 23 캜 to measure the thickness before charging in the second cycle. Subsequently, after charging again in the copper atmosphere, the thickness after charging in the second cycle was measured. Finally, the expansion ratio (%) = [(thickness after filling-thickness before filling) / thickness before filling] × 100 was calculated. At this time, the charging conditions were the same as those in the case of examining the cycle characteristics.

As shown in Table 14, in Examples 14-1 to 14-6 in which the composition of the solvent and the kind of the electrolyte salt were different, the discharge capacity retention ratio was significantly higher than in Comparative Example 2, as in Example 2-5. From this point, it was confirmed that, in the secondary battery of the present invention, the cycle characteristics were improved even when the composition of the solvent and the kind of the electrolyte salt were changed.

Particularly, in Examples 14-1 and 14-2, the discharge capacity retention ratio was higher than in Example 2-5. In this case, the discharge capacity retention rate tends to be higher in the case where the solvent contains DFEC than FEC. From these points, it was confirmed that when the fluorinated carbonate ester is contained in the solvent, the cycle characteristics are further improved, and a higher effect can be obtained by using difluoroethylene carbonate rather than carbonated monofluoroethylene as the fluorinated carbonic ester.

Further, in Examples 14-3 to 14-6, the discharge capacity retention ratio was higher than in Example 2-5. In this case, the discharge capacity retention rate tended to be higher in the case where the solvent contained VC or VEC than PRS or LiBF ₄ . From this viewpoint, cyclic carbonates having an unsaturated bond, a sulphone, or an electrolyte salt having boron and fluorine are contained in the solvent, the cyclic characteristics are further improved, and a cyclic carbonic ester having an unsaturated bond is used to obtain a higher effect .

Further, in Example 14-5 in which the solvent contained PRS, the expansion rate was significantly smaller than in Example 2-5, which did not include PRS. From this point, it was confirmed that in the secondary battery of the present invention, expansion characteristics were improved by containing sultone in the solvent.

(Example 15-1)

The procedure was the same as that of Example 2-5, except that a prismatic secondary battery shown in Figs. 5 and 6 was produced instead of the laminate film type secondary battery by the following procedure.

First, after the positive electrode 21 and the negative electrode 22 are fabricated, the positive electrode lead 24 made of aluminum and the negative electrode lead 25 made of nickel are welded to the positive electrode collector 21A and the negative electrode collector 22A, respectively Respectively. Subsequently, the positive electrode 21, the separator 23, and the negative electrode 22 were laminated in this order, wound in the longitudinal direction, and then formed into a flat shape. Thus, the battery element 20 was fabricated. Subsequently, after the battery element 20 is housed in the aluminum-made battery can 11, the insulating plate 12 is disposed on the battery element 20. Subsequently, after the positive electrode lead 24 and the negative electrode lead 25 are respectively welded to the positive electrode fins 15 and the battery can 11, the battery lid 13 is laser welded to the open end of the battery can 11 Respectively. Finally, an electrolytic solution was injected into the battery can 11 through the injection hole 19, and the injection hole 19 was sealed with the sealing member 19A, thereby completing the prismatic battery.

(Example 15-2)

A procedure similar to that of Example 15-1 was carried out except that the iron-made battery can 11 was used in place of the aluminum-made battery can 11.

The cycle characteristics of the secondary batteries of Examples 15-1 and 15-2 were examined, and the results shown in Table 15 were obtained. Table 15 also shows the results of Examples 2-5 and Comparative Example 2.

As shown in Table 15, in Examples 15-1 and 15-2 in which the battery structure was different, the discharge capacity retention ratio was significantly higher than that in Comparative Example 2, similarly to Example 2-5. In this case, the discharge capacity retention rate was higher than in Example 2-5, and the discharge capacity retention rate tended to be higher in the case where the battery can 11 was made of iron rather than aluminum. In view of these points, in the secondary battery of the present invention, the cycle characteristics are improved even when the cell structure is changed, and when the cell structure is made more square than the laminate film type, the cycle characteristics are further improved, It was confirmed that a higher effect can be obtained by using it. Further, although a specific embodiment is not described here, it is preferable that the rectangular secondary battery in which the sheath member is made of a metal material has improved cycle characteristics and expansion characteristics as compared with the laminate film secondary battery, It is clear that the same result is obtained in the secondary battery.

(Examples 16-1 to 16-4)

(Example 16-1) and 0.05 cm 3 / g (Example 16-1) of the extremely fine air group per unit weight of silicon by changing the reciprocating speed of the anode current collector 54A relative to the evaporation source, 2) and 0.01 cm 3 / g (Example 16-3) or 0 cm 3 / g (Example 16-4), respectively. The volume of the ultrafine air group per unit weight of the silicon is determined by subtracting the weight of the negative electrode collector 54A from the total weight of the negative electrode collector 54A on which the negative electrode active material is formed (the weight of silicon as the negative electrode active material) And the value of the amount of mercury penetration measured with respect to the pore diameter of 3 nm or more and 20 nm or less (the volume of the ultrafine air group) using a mercury porosimeter (Autopore 9500 series) manufactured by Micromeritics.

(Comparative Example 16)

The procedure was the same as that of Comparative Example 2 except that the volume of the ultrafine air group per unit weight of silicon was 0.3 cm 3 / g.

The cycle characteristics of the secondary batteries of Examples 16-1 to 16-4 and Comparative Example 16 were examined, and the results shown in Table 16 were obtained.

As shown in Table 16, in the case of forming the oxide-containing film, in Examples 16-1 to 16-4 in which the volume of the ultrafine air group per unit weight of silicon is 0.2 cm 3 / g or less, The capacity retention rate was remarkably increased, and when the discharge capacity was 0.05 cm 3 / g or less and 0 cm 3 / g, the discharge capacity retention ratio was further increased. In this case, when attention is paid to the difference between the three air groups (the fine air group or the very fine air group), in Examples 16-1 to 16-4 concerning the extremely fine air group, in Examples 2-1, 2-4, 2-6 and 2-9, the discharge capacity retention rate tended to be higher. This result shows that the volume of the micro air group has a larger effect on the volume of the negative electrode active material than the volume of the micro air group in reducing the surface area of the negative electrode active material. From these points, it was confirmed that in the secondary battery of the present invention, when the volume of the ultrafine air group per unit weight of silicon was 0.2 cm 3 / g or less when the oxide-containing film was formed, the cycle characteristics were further improved. In this case, it was also confirmed that a higher effect was obtained when the concentration was 0.05 cm 3 / g or less, particularly 0 cm 3 / g.

(Examples 17-1 to 17-4)

The volume of the ultrafine air group per unit weight of silicon was changed to 0.2 cm 3 / g (Examples 17-1) and 0.05 cm 3 / g (Example 17-1) by changing the reciprocating speed of the anode current collector 54A with respect to the evaporation source, 2) and 0.01 cm 3 / g (Example 17-3) or 0 cm 3 / g (Example 17-4), respectively.

(Comparative Example 17)

The procedure was the same as that of Comparative Example 6 except that the volume of the ultrafine air group per unit weight of silicon was 0.3 cm 3 / g.

The cycle characteristics of the secondary batteries of Examples 17-1 to 17-4 and Comparative Example 17 were examined, and the results shown in Table 17 were obtained.

As shown in Table 17, in Examples 17-1 to 17-4 in which the volume of the ultrafine air group per unit weight of silicon was 0.2 cm 3 / g or less in the case of forming the metal material, The capacity retention rate was remarkably increased, and when the discharge capacity was 0.05 cm 3 / g or less and 0 cm 3 / g, the discharge capacity retention ratio was further increased. In this case, in the same manner as the results shown in Table 16, in Examples 17-1, 17-3 and 17-4 relating to the extremely fine air group, in Examples 6-1, 6-3 and 6-6 The discharge capacity retention rate tends to be increased. From these points, it was confirmed that, in the secondary battery of the present invention, when the volume of the ultrafine air group per unit weight of silicon is 0.2 cm 3 / g when the metallic material is formed, the cycle characteristics are further improved. In this case, it was also confirmed that a higher effect was obtained when the concentration was 0.05 cm 3 / g or less, particularly 0 cm 3 / g.

From these results, it can be seen from the results shown in Tables 1 to 17 and Figs. 11 to 14 that, when the negative electrode active material contains silicon and has a micro air group (air air group of 3 nm or more and 50 nm or less in pore diameter) , It was confirmed that the cycle characteristics were improved without depending on the conditions such as the number of layers and the composition of the negative electrode active material by setting the volume of the fine air group per unit weight of silicon to 0.2 cm 3 / g or less.

Although the present invention has been described above with reference to the embodiments and the examples, the present invention is not limited to the embodiments described in the foregoing embodiments and examples, and various modifications are possible. For example, in the above-described embodiments and examples, the oxide film or the metal material is included in the micropores as necessary in order to make the volume of the fine air group per unit weight of silicon 0.2 cm 3 / g or less, . If the capacity of the fine air group is 0.2 cm 3 / g or less per unit weight of silicon, another filling material may be provided in the micropores. Needless to say, it is preferable that the filling material does not particularly affect the performance of the secondary battery.

In the above-described embodiments and examples, a description has been given of the lithium ion secondary battery in which the capacity of the negative electrode is shown based on the occlusion and release of lithium as the kind of the secondary battery. However, the present invention is not limited thereto. The secondary battery of the present invention is characterized in that the charging capacity of the negative electrode material capable of absorbing and desorbing lithium is made smaller than the charging capacity of the positive electrode so that the capacity of the negative electrode is accompanied by a capacity accompanied with insertion and extraction of lithium, And the secondary battery represented by the sum of the capacities.

In the above-described embodiments and examples, the case where the battery structure is a prismatic shape, the cylindrical shape, the laminate film type, and the case where the battery element has a winding structure has been described as an example, the secondary battery of the present invention may be a coin- The present invention is similarly applicable to a case where the battery cell has another cell structure or a case where the cell device has another structure such as a laminated structure.

In the above-described embodiments and examples, the case where lithium is used as the electrode reaction material has been described. However, it is also possible to use other lithium ions such as sodium (Na) or potassium (K) ) Or calcium (Ca), or other light metals such as aluminum may be used. This long-term periodic table is described in the revised edition of the Inorganic Chemical Nomenclature proposed by IUPAC (International Union of Applied Chemistry). In these cases as well, the negative electrode material described in the above embodiment can be used as the negative electrode active material.

In the above-described embodiments and examples, the numerical range derived from the results of the examples is described as an appropriate range with respect to the volume of the micro air group per unit weight of silicon in the negative electrode or the secondary battery of the present invention. However, Does not completely deny the possibility that the volume of the fine air group per unit weight of silicon falls outside the above-mentioned range. That is, the above-mentioned appropriate range is a particularly preferable range for achieving the effects of the present invention, and may be slightly deviated from the above range if the effect of the present invention can be obtained. This is not limited to the above-mentioned volume, but also the volume of the extremely fine air group per unit weight of silicon, the content of oxygen in the negative electrode active material, the ten point average roughness Rz of the surface of the negative electrode collector, and the like .

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a cross-sectional view showing the structure of a negative electrode according to one embodiment of the present invention. Fig.

FIG. 2 is a SEM photograph showing the cross-sectional structure of the negative electrode shown in FIG. 1, and a schematic view thereof. FIG.

3 is a view showing a distribution of rate of change of the amount of penetration of mercury.

4 is a SEM photograph showing another cross-sectional structure of the negative electrode shown in Fig. 1 and its schematic view.

5 is a cross-sectional view showing a configuration of a first secondary battery having a negative electrode according to an embodiment of the present invention.

6 is a cross-sectional view taken along line VI-VI of the first secondary battery shown in Fig. 5;

7 is a sectional view showing the configuration of a second secondary battery having an anode according to an embodiment of the present invention;

Fig. 8 is an enlarged cross-sectional view of a part of the wound electrode body shown in Fig. 7; Fig.

9 is a cross-sectional view showing the configuration of a third secondary battery having a negative electrode according to one embodiment of the present invention.

10 is a cross-sectional view taken along the line X-X of the wound electrode body shown in Fig.

11 is a view showing a correlation between a capacity and a discharge capacity retention rate;

12 is a diagram showing another correlation between the capacity and the discharge capacity retention rate;

13 is a view showing a correlation between an oxygen content and a discharge capacity holding ratio.

14 is a diagram showing a correlation between a ten-point average roughness and a discharge capacity retention rate;

Description of the Related Art

1, 22A, 42A, and 54A:

2, 22B, 42B, and 54B: negative electrode active material layer

11, 31: Battery cans

12, 32, 33: insulating plate

13, 34: Battery lid

14: Terminal board

15: Positive electrode pin

16: Insulation case

17, 37: Gasket

18: Opening valve

19: Injection ball

19A: sealing member

20: Battery element

21, 41, 53: Positive electrode

21A, 41A, and 53A:

21B, 41B, 53B: Positive electrode active material layer

22, 42, 54: Negative electrode

23, 43, 55: separator

24, 45, 51: positive lead

25, 46, 52: negative electrode lead

35: Safety valve mechanism

35A: Disc plate

36: Thermal Resistance Element

40, 50: wound electrode body

44: center pin

56: electrolyte

57: Protective tape

61: Adhesive film

60: outer member

201: Negative electrode active material particle

202 (202A to 202C): work

203: metal material

Claims (48)

A secondary battery comprising an electrolyte and a positive electrode and a negative electrode, Wherein the negative electrode has a negative electrode collector and a negative electrode active material layer formed thereon, Wherein the negative electrode active material layer comprises a negative electrode active material containing silicon (Si) Wherein the anode active material layer has a pore group of 3 nm or more and 50 nm or less in pore size, Wherein the negative electrode active material layer has at least one of an oxide-containing film and a metal material which is not alloyed with the electrode reaction material in the pores, Wherein the volume of the air cleaner having a pore size of 3 nm or more and 50 nm or less as measured by mercury porosimetry using a mercury porosimeter is 0.2 cm 3 / g or less per unit weight of silicon. The secondary battery according to claim 1, wherein the calorific value of the calorimetric group having a pore diameter of 3 nm or more and 50 nm or less, as measured by mercury porosimetry using a mercury porosimeter, is 0.05 cm 3 / g or less per unit weight of silicon. The secondary battery according to claim 1, wherein the calorimetric volume of the pore diameter of 3 nm or more and 50 nm or less as measured by mercury porosimetry using a mercury porosimeter is 0 cm 3 / g per unit weight of silicon. The secondary battery according to any one of claims 1 to 3, wherein the volume of the air cleaner having a pore size of 3 nm or more and 20 nm or less as measured by the mercury infiltration method using a mercury porosimeter is 0.2 cm 3 / g or less per unit weight of silicon. 5. The secondary battery according to claim 4, wherein the calorimetric volume of the pore diameter of 3 nm or more and 20 nm or less as measured by mercury porosimetry using a mercury porosimeter is 0.05 cm 3 / g or less per unit weight of silicon. The secondary battery according to claim 4, wherein the calorific value of the calorimetric group having a pore diameter of 3 nm or more and 20 nm or less as measured by the mercury porosimetry using a mercury porosimeter is 0 cm 3 / g per unit weight of silicon. The secondary battery according to claim 1, wherein the oxide containing film contains at least one oxide selected from the group consisting of silicon, germanium and tin. The secondary battery according to claim 1, wherein the oxide-containing film is formed by a liquid phase deposition method, a sol-gel method, a coating method, or a dip coating method. The secondary battery according to claim 1, wherein the metallic material contains at least one selected from the group consisting of Fe, Co, Ni, Zn, and Cu. . The secondary battery according to claim 1, wherein the metal material is formed by an electrolytic plating method or an electroless plating method. The secondary battery according to claim 1, wherein the negative electrode active material has a plurality of particle shapes. 12. The secondary battery according to claim 11, wherein the particle-shaped negative electrode active material has a multilayer structure. The secondary battery according to claim 1, wherein the negative electrode active material is formed by a vapor phase method. The secondary battery according to claim 1, wherein the negative electrode active material contains oxygen, and the content of oxygen in the negative electrode active material ranges from 3 atomic% to 40 atomic%. The secondary battery according to claim 1, wherein the negative electrode active material contains at least one metal element selected from the group consisting of iron, cobalt, nickel, chromium (Cr), titanium (Ti), and molybdenum (Mo) . The secondary battery according to claim 1, wherein the negative electrode active material is connected to the negative electrode collector and grows in the thickness direction of the negative electrode active material layer from the surface of the negative electrode collector. The secondary battery according to claim 1, wherein the secondary battery is a lithium ion secondary battery. A negative electrode current collector and a negative electrode active material layer formed on the current collector, Wherein the negative electrode active material layer comprises a negative electrode active material containing silicon, Wherein the anode active material layer has a pore group of 3 nm or more and 50 nm or less in pore size, Wherein the negative electrode active material layer has at least one of an oxide-containing film and a metal material which is not alloyed with the electrode reaction material in the pores, Characterized in that the volume of the repellent air of 3 nm or more and 50 nm or less in pore diameter measured by mercury porosimetry using a mercury porosimeter is 0.2 cm 3 / g or less per unit weight of silicon. delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete

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