WO2004042860A1

WO2004042860A1 - Nonaqueous electrolyte secondary battery

Info

Publication number: WO2004042860A1
Application number: PCT/JP2003/014154
Authority: WO
Inventors: Nao Shimura; Koshin Tanaka; Masahiro Sekino; Asako Satoh; Shusuke Inada; Akira Yajima; Masayuki Oguchi
Original assignee: Kabushiki Kaisha Toshiba
Priority date: 2002-11-06
Filing date: 2003-11-06
Publication date: 2004-05-21
Also published as: KR100778961B1; KR20050084919A; CN1711660A; CN1330046C

Abstract

A nonaqueous electrolyte secondary battery comprising a positive electrode containing positive electrode active substance particles in which lithium double oxide particles are contained, a negative electrode and a nonaqueous electrolyte, wherein the lithium double oxide particles have a composition containing element (M) being at least one member selected from the group consisting of Ni and Co, having a particulate form containing secondary agglomerates, and exhibit a peak intensity ratio satisfying the following formula (1), wherein the content of lithium double oxide particles in the positive electrode active substance particles is 50 wt.% or more, wherein the molar ratio of positive electrode active substance particles satisfies the following formula (2) and the particle diameter of volume cumulative frequency 90% (D90) with respect to the positive electrode active substance particles is in the range of 10 to 25 μm, and wherein the nonaqueous electrolyte contains a sultone compound having at least one double bond in its ring: 2 ≤ (I003/I104) < 5 (1) 0.95 ≤ (YLi/YM) ≤ 1.02 (2).

Description

Specification

Non-aqueous electrolyte secondary battery

Technical field

The present invention relates to a non-aqueous electrolyte secondary battery.

Background art

In recent years, electronic equipment such as mobile communication devices, notebook computers, palm-top personal computers, integrated video cameras, portable CD (MD) players, and cordless telephones have been downsized and lightened. Above, particularly small and large capacity batteries are required as power supplies for these electronic devices.

Examples of batteries that are widely used as power supplies for these electronic devices include primary batteries such as lithium-manganese batteries, and secondary batteries such as Eckel-cadmium batteries and lead-acid batteries. Among them, non-aqueous electrolyte secondary batteries using a lithium composite oxide for the positive electrode and a carbonaceous material capable of occluding and releasing lithium ion for the negative electrode are smaller, lighter, have higher cell voltages, and have higher cell voltages. Attention has been paid to obtaining energy density.

As a positive electrode active material for a nonaqueous electrolyte secondary battery, Japanese Unexamined 1 0 - The 6 9 9 1 0 JP general formula (I); Table in _{_{_{L i v xl N i ι_ χ2}}} Μ χ 0 2. The diffraction peak ratio at the (03) plane and the (104) plane at the Miller index hkl of X-ray diffraction (003) / (104) force is 1.2 or more, and the average particle diameter D Force 5 or more: L 0 im, lithium nickel composite oxide in which 10% of the particle size distribution is 0.5D or more and 90% is 2D or less.

However, such lithium-nickel composite oxides Secondary battery comprising a positive electrode, to produce the oxidative decomposition reaction of the nonaqueous electrolyte, the disclosure of _c inventions discharge cycle life is short gutter cormorants problems including

An object of the present invention is to provide a nonaqueous electrolyte secondary battery having an improved charge / discharge cycle life.

According to a first aspect of the present invention, there is provided a nonaqueous electrolyte secondary battery comprising: a positive electrode including a positive electrode active material containing a lithium composite oxide powder; a negative electrode; and a nonaqueous electrolyte. ,

Since the lithium composite oxide powder contains secondary aggregated particles, the molar ratio satisfies the following formula (A), the peak intensity ratio satisfies the following formula (B), and the volume cumulative frequency is 90%. Has a particle size (D90) of 10 / xm to 25xra,

The non-aqueous electrolyte, _t the non-aqueous electrolyte secondary battery comprising a sul tons compounds have a single double bond also rather small in the ring is provided

2 ≤ (I 003 / I 104) <5 (A)

_{0. 9 5 ≤ (X Li} / X M) ≤ 1. 0 2 (B) where, I is the Lithium complex oxide (0 0 3) in a powder X-ray diffraction of the powder surface of the peak intensity (cps) in, I丄04 Ri peak intensity (cps) der of (1 0 4) plane in the powder X-ray diffraction, X _U is the number of moles of lithium of the Li Chi um composite oxide powder, X _M Is the number of elements of the element M in the lithium composite oxide powder, and the element M is at least one selected from the group consisting of Ni and Co.

Further, according to the second aspect of the present invention, a positive electrode including positive electrode active material particles containing lithium composite oxide particles, a negative electrode, A nonaqueous electrolyte secondary battery comprising a nonaqueous electrolyte, wherein the lithium composite oxide particles contain at least one element M selected from the group consisting of Ni and Co. And has a particle morphology including secondary aggregates, and the peak intensity ratio satisfies the following expression (C),

The content of the lithium composite oxide particles in the positive electrode active material particles is 50% by weight or more;

The molar ratio of the positive electrode active material particles satisfies the following formula (D), and the particle diameter (D90) force of 90% of the volume cumulative frequency of the positive electrode active material particles is S 10 O / ir! Within the range of ~ 25 m,

2 ≤ (I 003 I 104) <5 (C)

0.95 ≤ (Y _Li / Y _Μ ) ≤ 1 · 0 2 (D) where I ₀₀₃ is the peak intensity (cps) of the (03) plane in the powder X-ray diffraction of the lithium composite oxide particles. in), I ₀₄ the Ri (1 0 4) the peak intensity of the face (cps) der in the powder X-ray diffraction, the Y _L i in moles of lithium in said positive electrode active material particle, Y _M is the In terms of the number of moles of the element M in the positive electrode active material particles, the element M is at least one selected from the group consisting of Ni and Co.

Brief description of drawings ^

FIG. 1 is a perspective view showing a thin non-aqueous electrolyte secondary battery which is an example of the non-aqueous electrolyte secondary battery according to the present invention.

Fig. 2 shows the thin non-aqueous electrolyte secondary battery of Fig. 1 along the Π _ Π line. FIG.

FIG. 3 is a partially cutaway perspective view showing a rectangular non-aqueous electrolyte secondary battery which is an example of the non-aqueous electrolyte secondary battery according to the present invention.

FIG. 4 is a partial cross-sectional view showing a cylindrical nonaqueous electrolyte secondary battery which is an example of the nonaqueous electrolyte secondary battery according to the present invention.

FIG. 5 is a characteristic diagram showing the 1H NMR spectrum of PRS contained in the nonaqueous electrolyte of the nonaqueous electrolyte secondary battery of Example 1, showing the best mode for carrying out the invention.

The first and second nonaqueous electrolyte secondary batteries according to the present invention will be described.

A first nonaqueous electrolyte secondary battery according to the present invention is a nonaqueous electrolyte secondary battery including a positive electrode including a positive electrode active material containing a lithium composite oxide powder, a negative electrode, and a nonaqueous electrolyte. hand,

The lithium composite oxide powder contains secondary aggregated particles and has a molar ratio satisfying the following formula (A), a peak intensity ratio satisfying the following formula (B), and a volume cumulative frequency of 90%. The particle size (D90) is in the range of 10 / im to 25 μπι,

The non-aqueous electrolyte contains a sulfonate compound having at least one double bond in a ring.

2 ≤ (I 003 / I 104) <5 (Α)

_{0. 9 5 ≤ (X Li} / X M) ≤ 1. 0 2 (B)伹to, I ₀₀₃ is the Lithium complex oxide (0 0 3) in a powder X-ray diffraction of the powder surface of the peak intensity ( cps), I 04 is the peak intensity (cps) of the (104) plane in the powder X-ray diffraction, and X Li is the lithium in the lithium composite oxide powder. Is the number of moles of titanium, and _Μ is the number of moles of the element M in the lithium composite oxide powder, and the element M is at least one selected from the group consisting of Ni and Co. is there.

The above-mentioned sultone compound can form a lithium ion permeable protective film on the positive electrode surface by opening a double bond and causing a polymerization reaction at the time of the first charge. On the other hand, the lithium composite oxide powder has a small expansion and contraction due to the occlusion and release of lithium, and at the same time, a protective coating is formed not only on the surface of the secondary aggregated particles but also on the gaps between the primary particles. Therefore, the protective coating can form a complicated network structure. As a result, the protective film can be prevented from peeling off from the positive electrode during the charge / discharge cycle, so that the oxidative decomposition reaction of the nonaqueous electrolyte can be suppressed, and the charge / discharge cycle of the secondary battery can be suppressed. The positive electrode, the negative electrode, and the non-aqueous electrolyte will be described below.

1) Positive electrode

The positive electrode includes a current collector, and a positive electrode layer supported on one or both surfaces of the current collector and containing the positive electrode active material, a binder, and a conductive agent.

The lithium composite oxide is synthesized, for example, by mixing the compounds of the respective constituent elements (for example, oxides and hydroxides) and then firing the mixture in the air or in an oxygen atmosphere.

The molar ratio of Li Ji U beam (X _L i) and the element M (X _M) of Li Ji U beam composite oxide (X _u / X jyr) ⁰ 9 5 ~:. To L 0 2 of within range. Explain the reason. When the molar ratio ( _XLi / XM) is less than 0.95, the crystallinity is remarkably reduced. Occlusion and release may hardly occur. On the other hand, those having a molar ratio ( _XLi / _XM ) force exceeding S 1.02 have excellent crystallinity, but the grain growth proceeds during firing, so that the ratio of single particles becomes high. As a result, not only does the expansion and contraction of lithium due to occlusion and release of lithium increase, but also the protective coating covering the primary particles becomes isolated, and a network structure cannot be obtained, resulting in charge and discharge. The protective coating may be easily peeled off in a short period of time, and the life of the charge / discharge cycle may be shortened. A more preferable range of the molar ratio ( _XLi / _XM ) is 0.997 to: L.02, and a more preferable range is 0.99 to: L.02. is there.

Examples of the lithium composite oxide include a lithium nickel composite oxide, a lithium cobalt composite oxide, a lithium nickel cobalt composite oxide, and the like. The lithium composite oxide may contain lithium and an element other than the element M. Examples of such elements include Mn, A1, SnFe, Cu, Cr, Zn, Mg, Si, P, F, Cl, B, and the like. You. The type of the added element may be one type or two or more types.

The lithium composite oxide has a positive electrode active material of 50 ° / ° C. It is desirable that they account for the above.

The reason for limiting the ratio (I 003 ZI 104) of the peak intensity I ₀₀₃ of the ( ₀₀₃ ) plane to the peak intensity I ₁₀₄ of the ( ₁₀₄ ) plane in powder X-ray diffraction will be described. The peak intensity ratio (I 003 / I 104) of 5 or more is excellent in crystallinity, but shows plate-likeness due to the progress of grain growth, that is, has high crystal orientation. Since the ratio of single particles is increased, the expansion and contraction of lithium due to occlusion and release of lithium are large, and the protective coating covering each primary particle is isolated, making it impossible to obtain a network structure. As a result, the charge / discharge cycle life may be shortened because the protective film is easily peeled off by repeating the charge / discharge cycle. By setting the peak intensity ratio (I 003 I 104) to 2 or more and less than 5, the ratio of secondary aggregated particles can be increased, and the expansion accompanying the occlusion and release of lithium can be achieved. ■ Shrinkage can be reduced. When the crystal has no orientation and is completely isotropic, the peak intensity ratio (I ₀₀₃ / I 104) is more preferable than the peak intensity ratio (I ₀₀₃ I 104) of 2 which is calculated. The preferred range is greater than 2 and less than 4.95.

The reason why the particle diameter (D 90) of the lithium composite oxide powder having a volume cumulative frequency of 90% is defined in the above range will be described. If the particle size is less than 0 9 0 10 β m, the number of primary particles constituting the secondary aggregated particles tends to be small, and the contact area between the secondary aggregated particles and the protective film is insufficient, and the protective film May be easily separated, and the life of the charge / discharge cycle may be shortened. On the other hand, when the D90 exceeds 25 m, the number of primary particles constituting the secondary aggregated particles is large, so that the protective coating does not spread inside the secondary aggregated particles and the surface of the secondary aggregated particles Only the state close to the state where only the protective coating is covered. For this reason, the protective film is easily peeled off during the charge / discharge cycle, and the life of the charge / discharge cycle may be shortened. A more preferred range for D90 is lOjun! ~.

Examples of the conductive agent include acetylene black and carbohydrate. Black, graphite and the like.

The binder has a function of holding the active material on the current collector and connecting the active materials. Examples of the binder include polytetrafluoroethylene (PTFE), polystyrene vinylidene (PVdF), polyethersulfone, and ethylene-propylene. One-gen copolymer (EPDM), styrene-butadiene rubber (SBR) and the like can be used.

The mixing ratio of the positive electrode active material, the conductive agent and the binder is set in the range of 80 to 95% by weight of the positive electrode active material, 3 to 20% by weight of the conductive agent, and 2 to 7% by weight of the binder. Is preferred.

As the current collector, a conductive substrate having a porous structure or a non-porous conductive substrate can be used. These conductive substrates can be formed, for example, of aluminum, stainless steel, or Eckel force.

The positive electrode is manufactured by, for example, suspending a conductive agent and a binder in a suitable solvent in a positive electrode active material, applying the suspension to a current collector, and drying to form a thin plate. You.

2) Negative electrode

The negative electrode includes a current collector and a negative electrode layer supported on one or both surfaces of the current collector.

The negative electrode layer contains a carbonaceous material that occludes and releases lithium ions and a binder.

Examples of the carbonaceous material include a graphite material, such as graphite, coke, carbon fiber, spherical carbon, pyrolysis gaseous carbonaceous material, and resin fired body, or a carbonaceous material; a thermosetting resin. , Isotropic pitch Mesophase pitch-based carbon, mesophase pitch-based carbon fiber, and mesophase spherules (especially, mesophase pitch-based carbon fiber has higher capacity / charge / discharge cycle characteristics. (Preferably), a graphite-based material or a carbonaceous material obtained by performing a heat treatment at 500 to 300 ° C. Above all, it is preferable to use a graphite material having graphite crystals in which the ( ₀₀₂ ) plane spacing d ₀₀₂ is _0.34 nm or less. A nonaqueous electrolyte secondary battery provided with a negative electrode containing such a graphitic material as a carbonaceous material can greatly improve the battery capacity and large-current discharge characteristics. More preferably, the plane distance d is 0.337 nm or less.

Examples of the binder include polytetrafluoroethylene (PTFE), polyvinylidene polyfluoride (PVdF), and ethylene propylene Polymer (EPDM), styrene-butadiene rubber (SBR), canolepoxy methinoresenolose (CMC) and the like can be used.

The mixing ratio of the carbonaceous material and the binder is preferably in the range of 90 to 98% by weight of the carbonaceous material and 2 to 20% by weight of the binder.

As the current collector, a conductive substrate having a porous structure or a non-porous conductive substrate can be used. These conductive substrates can be formed, for example, from copper, stainless steel, or nickel.

The negative electrode is obtained by, for example, kneading a carbonaceous substance that occludes and releases lithium ion and a binder in the presence of a solvent, and obtains a suspension. Is applied to a current collector, dried, and then pressed once or two to five times at a desired pressure in multiple steps. An electrode group is manufactured using the positive electrode and the negative electrode as described above.

This electrode group can be formed, for example, by (i) spirally winding a positive electrode and a negative electrode with a separator interposed therebetween, or (ii) flat-shaped by interposing a separator between the positive electrode and the negative electrode. (Iii) The positive and negative electrodes are spirally wound with a separator between them, and then compressed radially (iv) A separator is interposed between the positive and negative electrodes And then bent one or more times, or (V) a method of laminating a positive electrode and a negative electrode with a separator interposed therebetween.

The electrode group need not be pressed, but may be pressed to increase the integrated strength of the positive electrode, the negative electrode, and the separator. It is also possible to apply heating during pressing.

The electrode group may contain an adhesive polymer in order to increase the integration strength of the positive electrode, the negative electrode and the separator. Examples of the polymer having the adhesive property include polyacrylo-tolyl (PAN), polyatalylate (PMMA), and polyvinylidene fluoride (PVdF). , Polyvinyl chloride (PVC), or polyethylene oxide (PEO).

As a separator used for this electrode group, a microporous membrane woven fabric, a nonwoven fabric, a laminate of the same material or a different material thereof, or the like can be used. As a material for forming the separator, Polyethylene, polypropylene, ethylene-propylene copolymer, ethylene butene copolymer, and the like can be mentioned. As a material for forming the separator, one or more kinds selected from the above-mentioned types can be used.

The thickness of the separator is preferably 30 μπι or less, and more preferably 25 tm or less. The lower limit of the thickness is preferably set to 5 μm, and the more preferable lower limit is 8 μm.

The separator preferably has a heat shrinkage at 120 ° C. for one hour of not more than 20%. It is more preferable that the heat shrinkage is not more than 15%.

Preferably, the separator has a porosity in the range of 30 to 60%. A more preferred range of porosity is between 35 and 50%.

The separator preferably has an air permeability of not more than 600 seconds Z 100 cm ³ . Air permeability refers to the time (seconds) required for 100 cm ³ of air to pass through the separator. More preferably, the upper limit of the air permeability is set at 500 seconds Z l 0 0 cm ³ . The lower limit of the air permeability is preferably set to 50 seconds Z 100 cm 3, and the more preferable lower limit is 80 seconds Z 100 cm ³ .

It is desirable that the width of the separator be wider than the width of the positive electrode and the negative electrode. With such a configuration, it is possible to prevent the positive electrode and the negative electrode from directly contacting each other without passing through the separator. 3) Non-aqueous electrolyte

As the non-aqueous electrolyte, those having a substantially liquid or gel-like form can be used.

The non-aqueous medium and the electrolyte contained in the liquid non-aqueous electrolyte and the gel non-aqueous electrolyte will be described.

The non-aqueous solvent includes a slutone compound having at least one double bond in a ring.

Here, the sultone compound having at least one double bond in the ring may be sultone compound A represented by the following general formula (1) or sultone compound: Sulfon compound B in which at least one H of compound A is substituted with a hydrocarbon group can be used. In the present application, the sluton compound A or the sluton compound B may be used alone, or both the sluton compound A and the sluton compound B may be used.

(Formula 1)

0 one so 2

In mh _n of 1, the C _m H _n straight chain hydrocarbon group, m and n is an integer of 2 or more that satisfies 2 m> n.

Sulfon compounds having at least one double bond in the ring open a double bond by the reaction with the positive electrode, and a polymerization reaction occurs.Therefore, a lithium ion-permeable protective coating is formed on the positive electrode surface. Can be formed. Among the preferred sluton compounds, the compound having m = 3 and n = 4 among the sluton compounds A, that is, 1 3 — propene sultone (PRS) or a compound where m = 4, n = 6, ie, 1,4-butylene sultone (BTS). As the sultone compound, 1,3-propene sultone (PRS) or 1,4-butylene sultone (BTS) may be used alone, or these PRS and BTS may be used in combination.

It is desirable that the ratio of the sultone compound be not more than 10% by volume. This is because, when the ratio of the sultone compound exceeds 10% by volume, the above-mentioned protective coating becomes extremely thick, so that the lithium ion permeability is reduced and the discharge capacity at a temperature lower than room temperature is reduced. Because. Furthermore, in order to maintain a high discharge capacity even at a low temperature of, for example, 120 ° C., it is desirable that the proportion of the sulfur compound to be contained is not more than 4% by volume. In addition, in order to sufficiently secure the formation amount of the protective film, it is desirable that the ratio of the sulfur compound be at least 0.01% by volume. Furthermore, if the ratio of the sultone compound is at least 0.1% by volume, the protective function of the protective film can be sufficiently exhibited even at a higher temperature, for example, 65 ° C.

It is desirable that the non-aqueous solvent further contains ethylene carbonate (EC). EC content in non-aqueous solvent is 25 volumes. /. It is desirable to set it within the range of ~ 50 volume ° / ₀ . Thereby, a non-aqueous electrolyte having high conductivity and appropriate viscosity can be obtained. A more preferred EC content is 25 volumes. /. In the range of ~ 45% by volume.

As the non-aqueous solvent, other solvents can be used in combination with the sulfone compound and EC. Other solvents include, for example, linear Carbonates {eg, methyl carbonate (MEC), jeticarbonate (DEC), dimethycarbonate (DMC), vinylene carbonate (VC), vinylinolechi Lencarbonate (VEC), phenyleneethylene force component (phEC), propylene carbonate (PC) _γ -Petit mouth rattan (GBL), _y- (VL), methyl propionate (MP), ethyl propionate

(EP), 2 — methylfuran (2Me-F), fran (F) thiophene (TIOP), catechol carbonate (CATC), ethylenullite (ES) , 1 2 — 1 Crown 4

(Crown), tetraethylene glycol resin methylate ether (Ether), and the like. The type of other solvent can be one or more.

It is the electrolyte to be dissolved in the nonaqueous solvent, for example, perchloric Li Ji U beam _{(L i C 1 0 4)} , six full Tsu reduction-phosphate Li Ji U beam

(L i PF _6), four full Kkaho c acid Li Ji U beam (L i BF ₄₎ six full Tsu arsenic Li Ji U beam _{(L i A s F 6)} , Application Benefits off Ruoro meta sulfo Lithium phosphate (Li CF ₃ SO 3), bis trifluorene methinoles norre honinolei midium lithium [L i N (CF 3 SO 2) 2], L i N (C 2 F 5 SO ₂₎ Ru can and this include the 2 of which Li Ji Umushio. The type of electrolyte used can be one, two or more.

It is desirable that the amount of the electrolyte dissolved in the nonaqueous solvent be 0.5 to 25 mol ZL. A more preferred range is from 1 to 2.5 mol L. It is desirable that the liquid non-aqueous electrolyte contains a surfactant such as trioctyl phosphate (TOP) in order to improve the wettability with the separator. The amount of the surfactant added is preferably 3% or less, and more preferably in the range of 0.1 to 1%.

It is preferable that the amount of the liquid non-aqueous electrolyte is 0.2 to 0.6 g per unit battery capacity of 10 OmAh. A more preferred range for the mass of the liquid non-aqueous electrolyte is from 0.25 to 0.55 g ZLOOmAh.

A container for storing the above-described electrode group and the non-aqueous electrolyte will be described.

The shape of the container can be, for example, a cylindrical shape with a bottom, a rectangular tube with a bottom, a bag-like cup shape, or the like.

This container can be formed from, for example, a film including a resin layer, a metal plate, a metal film, or the like.

The resin layer contained in the film can be formed of, for example, polyolefin (for example, polyethylene, polypropylene), polyamide, or the like. Among films including a resin layer, it is preferable to use a laminated film in which a metal layer and protective layers disposed on both surfaces of the metal layer are integrated. The metal layer plays a role of blocking moisture and maintaining the shape of the container. Examples of the metal layer include aluminum, stainless steel, iron, and copper eckel. Of these, aluminum is preferred because it is lightweight and has a high moisture-blocking function. The metal layer may be formed of one kind of metal, but two or more kinds of metal layers may be formed. -It may be formed from a body. Of the two protective layers, the protective layer in contact with the outside serves to prevent damage to the metal layer. This external protective layer is formed of one type of resin layer or two or more types of resin layers. On the other hand, the inner protective layer plays a role in preventing the metal layer from being corroded by the non-aqueous electrolyte. This internal protective layer is formed of one type of resin layer or two or more types of resin layers. Further, a thermoplastic resin for sealing the container with a heat seal can be provided on the surface of the internal protective layer.

The thickness of the film including the resin layer is preferably set to 0.3 mm or less, more preferably 0.25 mm or less, and still more preferably 0.15 mm. Below, the most preferred range is 0.12 mm or less. In addition, since the thickness force is thinner than SO.05 mm and it is easy to deform or break, the lower limit of the film thickness is preferably set to 0.05 mm. New

The metal plate and the metal film can be formed of, for example, iron, stainless steel, or aluminum.

The thickness of the metal plate and the metal film is preferably set to 0.4 mm or less, a more preferred range is 0.3 mm or less, and a most preferred range is 0.25 mm or less. is there. If the thickness is less than 0.05 mm, sufficient strength may not be obtained.Therefore, the lower limit of the thickness of the metal plate and the metal film is set to 0.05 mm. I prefer to do it.

A second nonaqueous electrolyte secondary battery according to the present invention includes a positive electrode including positive electrode active material particles containing lithium composite oxide particles, and a negative electrode. A non-aqueous electrolyte secondary battery comprising: a lithium composite oxide particle comprising at least one element M selected from the group consisting of Ni and Co. And has a particle morphology including secondary agglomeration, and a peak intensity ratio satisfying the following formula (C),

The content of the lithium composite oxide particles in the positive electrode active material particles was 50% by weight. /. That is all

The molar ratio of the positive electrode active material particles satisfies the following formula (D), and the particle diameter (D90) of the above-mentioned positive electrode active material particles having a volume cumulative frequency of 90% is 10 111 to 25 / ^ 111. Within the range,

The non-aqueous electrolyte provides a non-aqueous electrolyte secondary battery including a sulfonate compound having at least one double bond in a ring ₍ ≤ (I 003 / I 104) <5 (C )

0.95 ≤ (Y _Li / Y _M ) ≤ 1.02 (D) where I ₀₀₃ is the peak intensity of the (03) plane in the powder X-ray diffraction of the lithium composite oxide particles. in cps), I i ₀₄ is the powder X-ray diffraction at (1 0 4) Ri peak intensity (cps) der the surface, Y _L i is the number of moles of lithium of the positive electrode active material particle, Y _M Is the number of moles of the element M in the positive electrode active material particles, and the element M is at least one selected from the group consisting of Ni and Co.

The second non-aqueous electrolyte secondary battery according to the present invention can have the same configuration as that described in the first non-aqueous electrolyte secondary battery except for the positive electrode. The following describes the positive electrode. <The positive electrode is supported on the current collector and on one or both sides of the current collector. And a positive electrode layer containing the positive electrode active material particles, a binder, and a conductive agent.

Peak intensity ratio of Lithium composite oxide particles containing an element M ⁽¹ 003 / I 104) of two or more, by a child of less than 5, with Ru can and this to increase the proportion of secondary agglomerated particles, Expansion due to occlusion / release of lithium ■ Shrinkage rate can be reduced. When the crystal has no orientation and is perfectly isotropic, the peak intensity ratio (I 003 I 104) is calculated as 2. A more preferred range of peak intensity ratios (I003ZI104) is greater than 2 and less than 4.95.

Since the positive electrode active material particles contain 50% by weight or more of lithium composite oxide particles having a peak intensity ratio (I 003 I 104) of 2 or more and less than 5, the molar ratio of the positive electrode active material particles (Y LiZ YM) is almost equal to the molar ratio of the lithium composite oxide particles. Therefore, the molar ratio of (YLiZ Y _M) to less than zero. 10 5, absorption and desorption of Lithium is mined in good Ri positive electrode active substance etc. decrease in crystallinity of Lithium double if oxide particles It may not happen. On the other hand, if the molar ratio _{_{(Y Li / Y M) 1}} . 0 2 yo Ri is rather large, though excellent in crystallinity of the Lithium complex oxide particles, high proportion of single particle of Lithium composite oxide particles Therefore, not only does the expansion and contraction of lithium due to occlusion and release of lithium increase, but also the protective coating covering the primary particles becomes isolated, making it difficult to obtain a network structure. As a result, the protective film is easily peeled off in the charge / discharge cycle, and the life of the charge / discharge cycle may be shortened. A more preferred range of the molar ratio (Y _L ; / Y) is 0.97-; L.02, and a more preferred range is 0.99-1.02.

Since the content of the lithium composite oxide particles in the positive electrode active material particles is 50% by weight or more, the particle size distribution of the lithium composite oxide particles is largely reflected in the particle size distribution of the positive electrode active material particles. . In the case where the particle diameter (D90) of the volume-accumulated frequency of the positive electrode active material particles of 90% is less than 10 Aim, the number of the primary particles constituting the secondary aggregated particles of the lithium composite oxide particles is small. Because of the tendency to be small, the contact area between the secondary aggregated particles and the protective film is reduced, and the protective film is easily peeled. Therefore, there is a possibility that a long charge / discharge cycle life cannot be obtained. On the other hand, the larger particles of 0.90 to 25111 tend to have a large number of primary particles constituting the secondary aggregated particles of the lithium composite oxide particles, so that the protective coating is formed inside the secondary aggregated particles. In many cases, only the surface of the secondary agglomerated particles is covered with a protective coating without passing through. For this reason, the protective film is easily peeled off during the charge / discharge cycle, and a long charge / discharge cycle life may not be obtained. A more preferred range for D 90 is 10 jum to 20 μm.

The higher the content of the lithium composite oxide particles in the positive electrode active material particles, the better the adhesion between the positive electrode and the protective coating.Therefore, to obtain a longer charge / discharge cycle life More preferably, the content of the lithium composite oxide particles in the positive electrode active material particles is set to 60% by weight or more, and more preferably to 70% by weight or more. New

As a lithium composite oxide containing the element M, for example, 20 Lithium nickel composite oxide, Lithium cobalt composite oxide Lithium Eckert cobalt composite oxide, and the like. Other types of elements can be added to the lithium composite oxide from the viewpoint of improving characteristics and the like. Examples of such elements include Mn, A1, Sn, Fe, Cu, Cr, Zn, Mg, Si, P, F, Cl, B, and the like. it can. The type of the additive element may be one type or two or more types.

Among them, a composition represented by the following formula (E) or (F) is preferable.

L i _fl C o _b M l _c 0 ₂ (E)

Here, Ml is one or more elements selected from the group consisting of Ni, Mn, B, Al and Sn, and the molar ratios ab and c are each 0.9. 5 ≤ a ^ l. 05, 0.95 ≤ b ≤ 1.05, 0 ≤ c ≤ 0.05, 0.95 ≤ b + c ≤ l. Further preferred ranges of the mole ratios a, b, and c are 0.97 a ^ l. 03 and 0.97 ≤ b ≤ 1.03 003.001. c ≤ 0.03.

L i _X N i _y C o _z M2 _w O 2 (F)

Here, M2 is one or more elements selected from the group consisting of Mn, B, Al, and Sn, and the molar ratios x, y, z, and w are each 0. 9 5 x ≤ l. 0 5, 0.7 ≤ y ≤ 0.95, 0.05 ≤ z ≤ 0.3, 0 ≤ w ≤ 0.1, 0.95 ≤ y + z + w ≤ l.05. Further preferred ranges of the monolith ratios x, y, and 0 are 0.97 x ≤ 1.03, 0.75 ≤ y ≤ 0.9, and 0.1 ≤ z ≤ 0.25. . More than monole ratio The preferred range is 0 ≤ w ≤ 0.07, the more preferred range is 0 ≤ w ≤ 0.05, and the most preferred range is 0 ≤ w ≤ 0.03. In order to sufficiently obtain the effect of adding the element M 2, the lower limit of the molar ratio w is preferably set to 0.001.

In the above-mentioned lithium composite oxide particles, not all particles need to have the same composition, and if the peak intensity ratio is 2 or more and less than 5, it is composed of two or more types of particles having different compositions. It may be.

In addition, the positive electrode active material particles may be formed from the above-described lithium composite oxide particles, but may include particles other than the lithium composite oxide particles.

Is the other particles, for example, the peak intensity ratio _{(I 0 0 3 / I 1} 04) is Ru can and this include the 5 yo Ri greater Lithium-containing composite oxide particles. Since the lithium-containing composite oxide particles have a high activity in a charged state, the positive electrode containing the lithium-containing composite oxide particles may be used in a non-aqueous electrolyte under a high temperature environment. And can react quickly. As a result, when the battery is stored in a charged state in a high-temperature environment, a protective film of a sulfonate compound can be quickly formed on the positive electrode surface, thereby suppressing the oxidative decomposition reaction of the nonaqueous electrolyte. It is possible. Therefore, the amount of gas generated when the secondary battery is stored in a high temperature environment in a charged state can be reduced, so that the battery can be prevented from swelling, and the life of the charge / discharge cycle can be reduced. It is possible to realize a secondary battery that is long and has suppressed swelling during high-temperature storage during charging. A more preferable range of the peak intensity ratio (I 003 I 104) is 7 or less. Above. In addition, the peak intensity ratio is larger than 50,000,

If the peak derived from the (104) plane is not detected, the upper limit of the peak intensity ratio is set to 500, because it may have a crystal structure that does not occlude lithium. This is desirable. In order to realize a secondary battery that has both excellent charge / discharge cycle life and high-temperature storage characteristics during charging, the positive electrode active material particles of lithium-containing composite oxide particles having a peak intensity ratio (I 003 I 104) greater than 5 are required. It is preferred that the proportion in the child be in the range of 0.1% by weight or more and less than 50% by weight. A more preferred range is from 0.5 to 48% by weight.

Examples of the lithium-containing composite oxide include a lithium-cobalt composite oxide. At least one kind of element different from the constituent elements can be added to the lithium-containing composite oxide. For example, Ni, Mn, A 1 , Sn, Fe, Cu, Cr, Zn, Mg, Si, P, F, CI, B, and so on. The composition of the lithium-containing composite oxide may be represented by the above-described formula (E) or (F).

In the lithium-containing composite oxide particles, not all particles need to have the same composition.If the peak intensity ratio is larger than 5, two or more types of particles having different compositions are used. It may be composed of

Examples of the conductive agent, the binder, and the current collector may be the same as those described in the first nonaqueous electrolyte secondary battery. The positive electrode is manufactured by, for example, suspending a conductive agent and a binder in a suitable solvent in a positive electrode active material, applying the suspension to a current collector, and drying the resultant to form a thin plate. You.

The positive electrode active material particles used in the above-described second nonaqueous electrolyte secondary battery according to the present invention contain 50% by weight or more of the lithium composite oxide particles containing the element M, and The material particles have a peak intensity ratio (I 003Z I 104) of 2 or more and less than 5 and have a particle form including secondary aggregated particles, and the molar ratio of the positive electrode active material particles (YL; ^Y M) is Since the particle diameter (D90) is within the range of 0.95 to 1.02 and the particle diameter (D90) of 90% of the volume cumulative frequency of the positive electrode active material particles is within the range of 110111 to 25111, It can form a protective film permeable to lithium ions on the surface of the positive electrode by reacting with the lithium compound. Since this protective coating is formed not only on the surface of the secondary aggregated particles but also on the gaps between the primary particles, it can have a complex network structure. As a result, the protective film can be prevented from peeling off from the positive electrode during the charge / discharge cycle, so that the oxidative decomposition reaction of the nonaqueous electrolyte can be suppressed, and the charge / discharge cycle of the secondary battery can be suppressed. The service life can be improved.

A thin, rectangular cylindrical nonaqueous electrolyte secondary battery, which is an example of the nonaqueous electrolyte secondary battery according to the present invention, will be described in detail with reference to FIGS.

FIG. 1 is a perspective view showing a thin non-aqueous electrolyte secondary battery which is an example of the non-aqueous electrolyte secondary battery according to the present invention. FIG. 2 is a diagram showing the thin non-aqueous electrolyte secondary battery of FIG. FIG. 3 is a cut-away partial cross-sectional view. FIG. 3 shows a rectangular non-aqueous electrolyte secondary battery according to the present invention. FIG. 4 is a partially cutaway perspective view showing a water electrolyte secondary battery, and FIG. 4 is a partial cross-sectional view showing a cylindrical non-aqueous electrolyte secondary battery which is an example of the non-aqueous electrolyte secondary battery according to the present invention.

First, a thin nonaqueous electrolyte secondary battery will be described.

As shown in FIG. 1, an electrode group 2 is accommodated in a container body 1 having a rectangular cup shape. The electrode group 2 has a structure in which a laminate including the positive electrode 3, the negative electrode 4, and the separator 5 disposed between the positive electrode 3 and the negative electrode 4 is wound into a flat shape. The non-aqueous electrolyte is held in electrode group 2. A part of the edge of the container body 1 is wide and functions as the cover plate 6. The container body 1 and the lid plate 6 are each composed of a laminated film force. The laminated film includes an external protective layer 7, an internal protective layer 8 containing a thermoplastic resin, and a metal layer 9 disposed between the external protective layer 7 and the internal protective layer 8. A lid 6 is fixed to the container body 1 by a heat seal using the thermoplastic resin of the inner protective layer 8, whereby the electrode group 2 is sealed in the container. A positive electrode tab 10 is connected to the positive electrode 3, and a negative electrode tab 11 is connected to the negative electrode 4. Each of the negative electrodes 4 is drawn out of the container and serves as a positive electrode terminal and a negative electrode terminal.

Next, the prismatic nonaqueous electrolyte secondary battery will be described.

As shown in FIG. 3, an electrode group 13 is housed in a bottomed rectangular cylindrical container 12 made of a metal such as aluminum, for example. The radiator 15 and the negative electrode 16 are laminated in this order, and are flatly wound. A spacer 17 having an opening near the center is located above the electrode group 13. Is placed.

The non-aqueous electrolyte is held in the electrode group 13. The sealing plate 18b, which has an explosion-proof mechanism 18a and has a circular hole near the center, is laser-welded to the opening of the container 12. The negative electrode terminal 19 is arranged in a circular hole of the sealing plate 18b via a hermetic seal. The negative electrode tab 20 pulled out from the negative electrode 16 is welded to the lower end of the negative electrode terminal 19. On the other hand, a positive electrode tab (not shown) is connected to a container 12 also serving as a positive electrode terminal.

Next, the cylindrical non-aqueous electrolyte secondary battery will be described. A cylindrical container 21 made of stainless steel and having a bottom has an insulator 22 disposed at the bottom. The electrode group 23 is housed in the container 21. The electrode group 23 includes a positive electrode 24, a separator 2

5, a strip formed by laminating the negative electrode 26 and the separator 25 is spirally wound so that the separator 25 is located outside.

The container 21 contains a non-aqueous electrolyte. The insulating paper 27 having an opening at the center is provided with the electrode group in the container 21.

It is located above 2 3. The insulating sealing plate 28 is the container

The sealing plate 28 is disposed in the upper opening of the container 2 and the vicinity of the upper opening is caulked inward.

Fixed to 1. The positive electrode terminal 29 is fitted in the center of the insulating sealing plate 28. One end of the positive electrode lead 30 is connected to the positive electrode 24, and the other end is connected to the positive electrode terminal 29. The negative electrode 26 is connected to a negative electrode terminal via a negative electrode lead (not shown). It is connected to the container 21 which is a child.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings described above.

(Example 1)

Lithium composite oxide particles having the composition shown in Table 1 below and having a volume cumulative frequency of 90% particle diameter D90 and a peak intensity ratio (I 003 ZI104) of the values shown in Table 1 below were prepared. . As a result of scanning electron microscopy (SEM) observation, it was confirmed that the lithium composite oxide particles contained secondary aggregated particles. The volume cumulative frequency 90% particle size D 90 and the peak intensity ratio (I ₀₀₃ ZI

104> was measured by the method described below.

Measurement of D90>

That is, the particle size of the lithium composite oxide particles and the volume occupied by the particles in each particle size section are measured by a laser diffraction scattering method. The particle size when the volume of the particle size section was accumulated to reach 90 ° / ₀ as a whole was defined as the volume cumulative frequency of 90% particle size.

For the X-ray diffraction measurement, RINT 2000 manufactured by Rigaku Corporation was used. The measurement was performed using Cu_Κα1 (wavelength: 1.5405 A) as an X-ray source under the following instrument conditions. The tube voltage is 40 kV, the current is 40 mA, the divergence slit is 0.5 °, the scatter slit is 0.5 °, and the receiving slit width is 0.15 mm. there were. In addition, a monochromator was used. The measurement was performed at a scanning speed of 2 ° / min, a scanning step of 0.01 °, and a scanning axis of 20Z0. I got it. 2 Θ = 45.0. ± 0.5. The peak of (104) plane was defined as the peak of (104) plane, and the peak of 26- 18.8 ° ± 0.2 ° was defined as the peak of (003) plane. The peak intensity (cps) was obtained by subtracting the background from the measured value of the diffraction pattern indicated by the two-axis.

Above Lithium composite oxide powder 9 0 wt%, and acetylene Les pump rack 5 weight ^_0/0, polyunsaturated Kka vinylene Li Den (Ρ V d F) 5 by weight ^_0/0 N- methylation _ 2 -Pyrrolidone (NMP) solution was added and mixed to prepare a slurry. The slurry is applied to both sides of a current collector made of aluminum foil having a thickness of 15 m, and then dried and pressed, so that the positive electrode layer is supported on both sides of the current collector. A positive electrode having the structure described above was produced. The thickness of the positive electrode layer was 60 / shade per side.

Mesophase pitch-based carbon fiber heat-treated at 300 ° C. as a carbonaceous material (plane spacing (d ₀₀₂ ) force S 0.33 determined by powder X-ray diffraction) powder and 9 5 by weight ^_0/0 6 nm), and a polyunsaturated Kka Vieri Den (PV d F) 5 wt ^_0/0 of dimethyl Chirufu Orumua mi de (DMF) solution was mixed, scan la rie Was prepared. The slurry is applied to both sides of a current collector made of a copper foil having a thickness of 12 zm, dried, and pressed to form a negative electrode having a structure in which a negative electrode layer is supported on the current collector. Was prepared. The thickness of the negative electrode layer was 55 μιη per one side.

The plane distance d ₀₀₂ of the ( ₀₀₂ ) plane of the carbonaceous material was determined from the powder X-ray diffraction spectrum by the half-width midpoint method. At this time, scattering correction such as Lorentz scattering was not performed. <Separator>

A separator consisting of a microporous polyethylene membrane with a thickness of 25 μm was prepared.

Preparation of non-aqueous electrolyte solution>

Ethylene carbonate (EC), 1-butyrolataton (GBL) and 1,3-propeneluton (PRS) are converted to volume ratio (EC: GBL: PRS) force S33: 66: 1. To obtain a non-aqueous solvent. The resulting non-aqueous solvent to the four full Tsu of e Usanri lithium (L i BF ₄₎ whose concentration 1.5 mol Z

The liquid non-aqueous electrolyte was prepared by dissolving so as to obtain L.

Production of electrode group>

A positive electrode lead made of strip-shaped aluminum foil (100 m thick) is ultrasonically welded to the positive electrode current collector, and a strip-shaped nickel foil (100 mm thick) is formed on the negative electrode current collector. zm) was subjected to ultrasonic welding, then the positive electrode and the negative electrode were spirally wound therebetween through the separator, and then formed into a flat shape to produce an electrode group.

A 100-μm-thick laminate film with both sides of aluminum foil covered with polyethylene was formed into a rectangular cup shape by a press machine, and the inside of the container was obtained. The above-mentioned electrode group was housed.

Next, moisture contained in the electrode group and the laminate film was removed by subjecting the electrode group in the container to vacuum drying at 80 ° C. for 12 hours.

Next, a liquid non-aqueous electrolyte was charged to the electrode group in the By injecting so that the amount per Ah becomes 4.8 g and sealing with a heat seal, it has the structure shown in Figs. A thin non-aqueous electrolyte secondary battery with a power of 3.6 mm, a width of 3.5 mm, and a height of 62 mm was assembled.

(Examples 2 to 8)

A thin non-aqueous electrolyte secondary battery was assembled in the same manner as described in Example 1 except that the composition of the non-aqueous electrolyte was changed as shown in Table 2 below.

In Table 2, DEC indicates getyl carbonate, MEC indicates methylethyl carbonate, PC indicates propylene carbonate, and BTS indicates 1,4-butylenetone.

(Examples 9 to 17)

The molar ratio of _Li to element M ( _XLi / _XM ), peak intensity ratio (I003 / I104) and volume cumulative frequency 90% particle size D90 should be changed as shown in Table 1 below. A thin non-aqueous electrolyte secondary battery was assembled in the same manner as described in Example 1 except for (Comparative Examples 1 to 5).

A thin nonaqueous electrolyte secondary battery was assembled in the same manner as described in Example 1 except that the composition of the nonaqueous electrolyte was changed as shown in Table 4 below.

In Table 4, EC is ethylene carbonate, MEC is methynoleethyl carbonate, PRS is 1,3-propene snorethone, DEC is getyl carbonate, and GBL is γ-butyrolata. Tone and PC indicate propylene carbonate, and PS indicates propane sultone. (Comparative Examples 6 to 10)

The molar ratio of Li to element M (XLi / M), peak intensity ratio (I003 / I104) and volume cumulative frequency 90% particle size D90 should be changed as shown in Table 3 below. Except for the above, the thin batteries of Examples 1 to 17 and Comparative Examples 1 to 10 obtained by assembling a thin nonaqueous electrolyte secondary battery in the same manner as described in Example 1 above were used. The charge-discharge cycle characteristics were evaluated under the conditions described below, and the results are shown in Tables 2 and 4 below.

(Charge / discharge cycle characteristics)

For each rechargeable battery, as a first charge / discharge step, constant current to 4.2 V at 0.2 C (130 mA) at room temperature, constant voltage charge was performed for 15 hours, and then 0 Discharge to 3.0 V at 2.2 C Next, the charge and discharge cycle characteristics were as follows: charge and discharge rate 1 C, charge end voltage 4.2 V, discharge end voltage 3.0 OV charge / discharge test The discharge capacity retention rate after the charge and discharge was repeated 500 times in an environment at a temperature of 20 ° C (assuming the capacity of the first discharge was 100%) was determined.

table 1

Lithium composite oxide yarn! ^ Li and element M mole dan peak intensity ratio

(I nn ΠΛ) Example 1 L i C O O 1.00 3.4 Example 2 L ί C O O 1.00 3.4 Example 3 L i C O 2 1.00 3.4 Example Example 4 L i C Oo 1.00 3.4 Example 5 L i C 0 ₂ 1.00 3.4 Example 6 L i C Oo 1.00 3.4 Example 7 L i C Oo 1.00 3 . 4 Example 8 LiCoOo 1.00 3.4 Example 9 LiCoOo 1.00 2.43 Example 10 LiCoo 1.00 2.65 Example 11 Li0.996. 0 ₂ 0.96 2.8 Example 12 L i l.OlC 0 ₂ 1.01 2.4 Example 13 ^L i i.oiC o0 ₂ 1.01 2.17 Example 14 ^{L 1} 0.998 ^N i 0.2 ^C ° 0.8 ° 2 0. 998 3. 87 example _{15 L i N i o.2Coo. 8} 0 2 1. 00 2. 55 example ^{16 L i N i o.5 C o} 0.5 ° 2 1. 00 4. 23 Example 17 L i N i o.8 ^{C o} 0.2 ° 2 1.00 3.88

Table 2

Table 3

Table 4

The main 500 cycles Tokiyo 4ϋ lifting of the solvent type and the mixing ratio electrolytes Surutoni匕合product (% denotes the volume ^_0/0) type and mixing ratio (%) Comparative Example 1 33. 4% EC, 66. 6 % GBL 1.5 M-LiBF ₄ not added 4 2 Comparative Example 2 50% EC, 50% PC 1.0 M-LiPF ₆ not added 20

Comparative Example 33 33.4 EC, 66.6% MEC 1.0 M-LiPF ₆ not added 3 6

Comparative Example 33.4% EC, 33.3% MEC, 33.3% DEC 1.0 M-LiPF ₆ not added 4 2

Comparative Example 5 33 EC, 66% GBL 1 . 5M-LiBF 4 PS- 1 volume ^_0/0 3 5 Comparative Example 6 33 EC, 66% GBL 1 . 5M-LiBF 4 PRS- 1% 6 6

Comparative Example 7 33 EC, 66% GBL 1.5 M-LiBF ₄ PRS-1 volume ⁰ / o 6 2

Comparative Example 8 33% EC, 66% GBL 1. 5M-LiBF 4 PRS- 1 fireman's standard ^_0/0 5 8

Comparative Example 9 33 EC, 66% GBL 1.5 M-LiBF ₄ PRS-1 1 body ⁰ / o 3 8

. Comparative Example 10 33 EC, 66% GBL 1 5M-LiBF 4 PRS - 1 volume ^_0/0 2 3

Tables 1 to cormorants by kana 4 force RaAkira et tables, the molar ratio (X _Li / X _M) to zero. 9 5 to 1.0 in the second range, the peak intensity ratio (I 003 ZI 104) is 2 or more , A lithium composite oxide having a power of less than 5 and a power of D90 in the range of 10 μm to 25 μm, and a sultone having at least one double bond in the ring. It can be understood that the secondary batteries of Examples 1 to 17 containing the compound have a higher capacity retention rate during 50,000 cycles than the secondary batteries of Comparative Examples 1 to 10. Among them, the secondary batteries of Examples 1 to 12 and 14 to 17 have a value of 50,000 compared with the secondary battery of Example 13 which exceeds D90; ^ 20 μΐη. The capacity retention rate during the cycle has increased.

The peak intensity ratio of the secondary batteries of Comparative Examples 1 to 4 in which no sulfonate compound was added and the secondary battery of Comparative Example 5 in which PS having no double bond was used as an additive were 5 or more. Comparative Examples 6 and 10 in which the molar ratio is greater than 1.02 and the peak intensity ratio is greater than 5 in Comparative Examples 6 and 10 in which D90 is less than 10 m and D90 is less than 10 m. And the secondary battery of Comparative Example 8 in which the molar ratio is greater than 1.02, the peak intensity specific power is greater than 5, and the D90 force is less than 10 μππι. In all of the secondary batteries of Comparative Example 9 where 0 exceeds 25 im, the capacity retention rate during the 500 cycles was less than 70% .o

(Example 18)

D 90 force S 15 · 25 μm, the peak intensity ratio (I ₀₀₃ ZI 104) of 3.4 LiCo ₂ particles (first active material particles) of 3.4, 70 weight ⁰ / _0, D 9 0 force S 1 4. 9 3 in mu m, the peak intensity ratio (I 003Z I 104) force L i of ^{_{S 3 · 8 n i 0 .8}} c 0 0.2 M n 0.06_Rei 2 The cathode active material particles were obtained by mixing the particles (second active material particles) with 30% by weight. Scanning electron microscope (SEM) observations confirmed that some of the first active material particles were in the form of secondary aggregates.

Table 5 shows D90 of the obtained positive electrode active material particles and the molar ratio ( _YLI / YM).

A thin non-aqueous electrolyte secondary battery having the same configuration as that described in Example 1 was obtained except that the obtained positive electrode active material particles were used.

(Examples 19 to 24)

Composition, peak intensity ratio (Io03Z1104) and D90 in the first active material and the second active material, the compounding ratio of the first active material in the positive electrode active material particles, and the positive electrode active material particles Except for using the positive electrode active material particles whose D90 and molar ratio (YUZYM) are as shown in Table 5 below, a thin structure having the same configuration as that described in Example 1 described above. A non-aqueous electrolyte secondary battery was obtained.

With respect to the obtained secondary batteries of Examples 18 to 24, the capacity retention rate during 500 cycles was measured in the same manner as described in Example 1 described above, and the results were shown in Table 6 below. Shown in Further, the charging and high-temperature storage characteristics of the secondary batteries of Examples 18 to 24 and Example 1 described above were evaluated under the conditions described below, and the results are shown in Table 6 below.

(Charge high temperature storage characteristics)

Each rechargeable battery is charged at a charge rate of 1 C and a charge termination voltage of 4.2 V, and stored for 120 hours in an environment at a temperature of 80 ° C The thickness of the battery container after the storage was measured, and the rate of change in the thickness of the battery container during storage was determined by the formula (I).

_{{(Ti - t 0) /} t 0 lioo (%) (I) where the to the battery container the thickness of the immediately preceding storage, wherein ti represents the battery case thickness after storage 1 2 0 hours.

Table 6

As is clear from Tables 5 and 6, the positive electrode composed of two types of lithium cobalt-containing composite oxides having peak intensity ratios (I 003 / I! 04) of 2 or more and less than 5 The batteries of Examples 18 to 19 provided with the positive electrode containing the active material had a higher cycle maintenance ratio and a slightly higher thickness change ratio than those of Example 1.

In addition, a lithium element M-containing composite oxide having a peak intensity ratio (I 003, I 104) of 2 or more and less than 5 and a lithium-containing composite oxide having a peak intensity ratio (I 003 ZI 104) of more than ⁵ The secondary batteries of Examples 20 to 24 provided with a positive electrode containing a composite oxide and, while maintaining a high capacity retention rate during 50,000 cycles, and expanding during charge high-temperature storage. This could be made smaller than in Example 1.

In the above-described examples, when the number of moles of the element M in the positive electrode active material particles is Ni or Co in the positive electrode active material particles, When Ni and Co are contained in the positive electrode active material particles, it is the total number of moles of Ni and Co.

(How to detect PRS)

Further, with respect to the secondary battery of Example 1, after the initial charge / discharge step, the circuit was opened for 5 hours or more, and after the potential was sufficiently settled, the Ar concentration was 99.9 ° /. As described above, the electrode group was taken out by decomposing it in a glove box having a dew point of 150 ° C or less. The electrode group was packed in a centrifuge tube, dimethylsulfoxide (DMSO) -d6 was added thereto, sealed, taken out of the glove box, and centrifuged. Thereafter, the in Gurobubo Tsu the click scan were taken mixed solution of DMSO-d ₆ and the electrolyte from the centrifugation tube. About 0.5 ml of the mixed solvent was put into a sample tube for NMR of 5ιηιηψ, and NMR measurement was performed. The apparatus used for the NMR measurement was JNM-LA400WB manufactured by JEOL Ltd., the observation nucleus was ¹ H, the observation frequency was 400 MHz, and dimethinoresulfoxydide (DMSO). -The residual proton signal slightly contained in d6 was used as an internal standard (2.5 ppm). The measurement temperature was 25 ° C. ^{In the 1} HNMR spectrum, the peak corresponding to EC is around 4.5 ppm, and the peak corresponding to PRS is around 5.1 ppm (P], as in the spectrum shown in Fig. 5). _), Observed near 7.05 ppm (P ₂ ) and 7.2 ppm (P ₃ ) Was done. From these results, it was confirmed that PRS was contained in the nonaqueous solvent present in the secondary battery of Example 1 after the first charge / discharge step.

Further, an observation frequency was 1 0 0 MH _Z, dimethylsulfoxide Shi de (DMSO) - d 6 (. 3 9 5 ppm) This filtration and was subjected to to ¹³ CNMR measurement an internal standard substance, to the EC Corresponding peaks: 66 p: m, peaks corresponding to PRS: 74 ppm, 124 ppm, and 140 ppm. Observed from these results. It was confirmed that PRS was contained in the non-aqueous solvent in the secondary battery of No. 1.

Furthermore, when the ratio of the PRS NMR integrated intensity to the EC NMR integrated intensity in the iH NMR spectrum was determined, the ratio of PRS to the total non-aqueous solvent was smaller than before the secondary battery assembly. I was able to confirm that

The present invention is not limited to the above-described embodiment, but can be similarly applied to other types of combinations of a positive electrode, a negative electrode, a separator, and a container.

Industrial applicability

As described above in detail, according to the present invention, it is possible to provide a non-aqueous electrolyte secondary battery having an improved charge / discharge cycle life.

Claims

The scope of the claims

1. A non-aqueous electrolyte secondary battery comprising: a positive electrode containing positive electrode active material particles containing lithium composite oxide particles; a negative electrode; and a non-aqueous electrolyte,

The lithium composite oxide particles have a composition including at least one element M selected from the group consisting of Ni and Co, and have a particle form including secondary aggregated particles. And the peak intensity ratio satisfies the following equation (1),

The molar ratio of the positive electrode active material particles satisfies the following formula (2), and the particle diameter (D90) at a volume cumulative frequency of 90% in the positive electrode active material particles is 10! ~ 25 / x m

The non-aqueous electrolyte contains a sluton compound having at least one double bond in a ring.

2 ≤ (I 003 I 104) <5 (1)

_{0. 9 5 ≤ (Y Li} / Y M) ≤ 1. 0 2 (2) where, I is the Lithium composite oxide powder X Senkai (0 0 3) in the folding plane of the peak intensity of the particles (cps) _Where I ₀₄ is the peak intensity (cps) of the ( ₁₀₄ ) plane in the powder X-ray diffraction, Y _U is the number of moles of lithium in the positive electrode active material particles, and Y _M is the positive electrode active material. The number of moles of the element M in the material particles is at least one selected from the group consisting of Ni and Co.

2. The peak intensity ratio (I 003 I 104) is larger than 2,

2. The non-aqueous electrolyte secondary battery according to claim 1, which is 4.95 or less.

3. The number of moles (Y _Li / Y _M) is 0. 9 7 above, 1. 0 2 or less non-aqueous electrolyte secondary battery of claim 1, wherein.

4. The non-aqueous electrolyte secondary battery according to claim 1, wherein the 90% particle size (D90) of the volume cumulative frequency is not more than 2 μμη.

5. The lithium composite oxide particles are selected from the group consisting of Mn, A1, Sn, Fe, Cu, Cr, Zn, Mg, Si, P, F, CI, and B. 2. The non-aqueous electrolyte secondary battery according to claim 1, further comprising at least one selected element.

6. The non-aqueous electrolyte secondary battery according to claim 1, wherein the positive electrode active material particles are composed of the lithium composite oxide particles.

7. The non-aqueous electrolyte secondary battery according to claim 1, wherein the positive electrode active material particles further include a lithium-containing composite oxide particle having a peak intensity ratio satisfying the following expression (3).

(I 003, I 104)> 5 (3)

Here, I is the peak intensity (cps) of the (03) plane in the powder X-ray diffraction of the lithium-containing composite oxide particles, and I i04 is the peak of the (104) plane in the powder X-ray diffraction. Strength

(cpS).

8. The non-aqueous electrolyte secondary battery according to claim 7, wherein the lithium-containing composite oxide particles satisfying the formula (3) further contain Co.

9. The content of the lithium-containing composite oxide particles satisfying the formula (3) in the positive electrode active material particles is 0.1% by weight or more and 50% by weight. /. 8. The non-aqueous electrolyte secondary battery according to claim 7, which is less than.

10. Including positive electrode active material containing lithium composite oxide powder A non-aqueous electrolyte secondary battery comprising a positive electrode, a negative electrode, and a non-aqueous electrolyte,

Since the lithium composite oxide powder contains secondary aggregated particles, the molar ratio satisfies the following expression (4), the peak intensity ratio satisfies the following expression (5), and the volume cumulative frequency is 90 °. /. Has a particle size (D 90) in the range of 10 μm to 25 μιη,

2 ≤ (I 003 / I 104) 5 ()

_{0. 9 5 ≤ (X Li} / X M) ≤ 1. 0 2 (5) where, I is the Lithium composite oxide powder X-ray diffraction in the (0 0 3) powder surface of the peak intensity (cps) _Where I ₀₄ is the peak intensity (cps) of the ( ₁₀₄ ) plane in the powder X-ray diffraction, X _U is the number of moles of lithium in the lithium composite oxide powder, and X _M is the In terms of the number of moles of the element M in the lithium composite oxide powder, the element M is at least one selected from the group consisting of Ni and Co.

11. The non-aqueous electrolyte secondary battery according to claim 10, wherein the content of the lithium composite oxide powder in the positive electrode active material is 50% by weight or more.

12. The non-aqueous electrolyte according to claim 1 or 10, wherein the sultone compound is composed of at least one of 1,3-propene sultone and 1,4 butyl seletone. Next battery.